微信公众号随时随地查标准

QQ交流1群(已满)

QQ群标准在线咨询2

QQ交流2群

购买标准后,可去我的标准下载或阅读

5.1 DPGBE and EGBE have a variety of residential and industrial applications such as cleaning formulations, surface coatings, inks, and cosmetics. These analytes may be released into the environment at levels that may be harmful to aquatic life.5.2 This test method has been investigated for use with reagent and sea water.1.1 This test method covers the determination of dipropylene glycol monobutyl ether (DPGBE) and ethylene glycol monobutyl ether (EGBE) in sea water by direct injection using liquid chromatography (LC) and detection with tandem mass spectrometry (MS/MS). These analytes are qualitatively and quantitatively determined by this test method. This test method adheres to selected reaction monitoring (SRM) mass spectrometry.1.2 The detection verification level (DVL) and reporting range for DPGBE and EGBE are listed in Table 1.1.2.1 The DVL is required to be at a concentration at least 3 times below the reporting limit (RL) and have a signal/noise ratio greater than 3:1. Fig. 1 and Fig. 2 display the signal/noise ratio of the single reaction monitoring (SRM) transition.FIG. 1 Detection Verification Level Signal/Noise RatioFIG. 2 Reporting Level (Calibration Standard) Signal/Noise Ratio1.2.2 The reporting limit is the concentration of the Level 1 calibration standard as shown in Table 4 for DPGBE and EGBE, taking into account the 20 % sample preparation dilution factor.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价: 590元 / 折扣价: 502 加购物车

在线阅读 收 藏

5.1 Separation and identification of stabilizers used in the manufacture of polyethylene are necessary in order to correlate performance properties with polymer composition.5.2 The BHT extraction procedure is made effective by the insolubility of the polymer sample in solvents generally used for gas chromatographic analysis.1.1 This test method describes a procedure for the determination of butylated hydroxy toluene (BHT) (2,6-di-t-butyl-4-methyl-hydroxybenzene) in polymers of ethylene and ethylene-vinyl acetate (EVA) copolymers by solvent extraction followed by gas chromatographic analysis. Detection of the compound is achieved by flame ionization, and quantitative analysis is obtained by use of internal or external standards, as described in Practices E260, E355, and E594.1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 9.NOTE 1: There is no known ISO equivalent for this test method.

定价: 515元 / 折扣价: 438 加购物车

在线阅读 收 藏

1.1 This specification covers the requirements for a prediluted aqueous ethylene glycol base low-silicate engine coolant (50 volume percent minimum) for cooling systems of heavy-duty engines. When used without further dilution, this product will function effectively during both summer and winter to provide protection from corrosion, freezing at least to -36.7°C (-34.0°F), and boiling at least to 108°C (226°F). 1.2 Prediluted coolant meeting this specification requires both an initial charge of a supplemental coolant additive (SCA) and regular maintenance doses of an SCA to continue the protection in certain operating heavy-duty engine cooling systems, particularly those of the wet cylinder liner-in-block design. The SCA additions are defined by and are the primary responsibility of the engine or vehicle manufacturer. If they provide no instructions, follow the SCA supplier's recommended instructions. 1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

定价: 0元 / 折扣价: 0

在线阅读 收 藏

5.1 Properties of EVA copolymers are affected by the amount of vinyl acetate incorporated in the copolymer: This test method provides a means to determine the vinyl acetate level in copolymer samples.5.2 Before proceeding with this test method, reference should be made to the specification of the material being tested. Any test specimen preparation, conditioning, dimensions, or testing parameters, or a combination thereof, covered in the materials specification shall take precedence over those mentioned in this test method. If there are no material specifications, then the default conditions apply.1.1 This test method covers infrared procedures for determining the vinyl acetate content of EVA copolymers using pressed films (Procedure A) or molded plaques (Procedure B) and internal corrections for sample thickness.1.2 This test method is applicable to the analysis of EVA copolymers containing 0.5 to 55 % vinyl acetate except as specified in 1.3.1.3 Talc interferes with the 1020 cm−1 vinyl acetate band. Resins containing <5 % vinyl acetate and talc are excluded from the scope of this test method.1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are provided for information purposes only.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 8.NOTE 1: There is no known ISO equivalent to this standard.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价: 590元 / 折扣价: 502 加购物车

在线阅读 收 藏

1.1 This specification covers flexible sheet made from ethylene propylene diene terpolymer (EPDM) geomembrane intended for use in geotechnical and geoenvironmental applications. The tests and property limits used to characterize the sheet are values to ensure minimum quality for the intended use. The vulcanized rubber sheet may be non-reinforced, fabric or scrim reinforced.1.2 In-place geomembrane design criteria, such as field seaming strength and material compatibility, among others, are factors that must be considered but are beyond the scope of this specification.1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价: 590元 / 折扣价: 502 加购物车

在线阅读 收 藏
ASTM D2693-22 Standard Specification for Ethylene Glycol Active 发布日期 :  1970-01-01 实施日期 : 

This specification establishes the properties and requirements for ethylene glycol for use in the preparation of surface coatings. The material shall be appropriately sampled and tested, and shall conform to the following specified requirements: apparent specific gravity; color (Pt-Co units); distillation range (initial boiling point and dry point); water content; acidity as acetic acid; diethylene glycol content; and iron content.1.1 This specification covers ethylene glycol for use in the preparation of surface coatings.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 The following applies to all specified limits in this standard; for purposes of determining conformance with this standard, an observed value or a calculated value shall be rounded off “to the nearest unit” in the last right-hand digit used in expressing the specification limit, in accordance with the rounding-off method of Practice E29.1.4 For specific hazard information and guidance, consult the supplier's Material Safety Data Sheet.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价: 515元 / 折扣价: 438 加购物车

在线阅读 收 藏

5.1 The freezing point of an engine coolant indicates the coolant freeze protection.5.2 The freezing point of an engine coolant may be used to determine the approximate glycol content, provided the glycol type is known.5.3 Freezing point as measured by Test Method D1177 or approved alternative method is a requirement in Specifications D3306 and D6210.5.4 This test method provides results that are equivalent to Test Method D1177 and expresses results to the nearest 0.1 °C with improved reproducibility over Test Method D1177.5.5 This test method determines the freezing point in a shorter period of time than Test Method D1177.5.6 This test method removes most of the operator time and judgement required by Test Method D1177.1.1 This test method covers the determination of the freezing point of an aqueous engine coolant solution.1.2 This test method is designed to cover ethylene glycol base coolants up to a maximum concentration of 60 % (v/v) in water; however, the ASTM interlaboratory study mentioned in 12.2 has only demonstrated the test method with samples having a concentration range of 40 % to 60 % (v/v) water.NOTE 1: Where solutions of specific concentrations are to be tested, they shall be prepared from representative samples as directed in Practice D1176. Secondary phases separating on dilution need not be separated.NOTE 2: The products may also be marketed in a ready-to-use form (prediluted).1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Some specific hazards statements are given in 7.3.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价: 590元 / 折扣价: 502 加购物车

在线阅读 收 藏

5.1 Leakage of aqueous engine coolant into the crank case weakens the ability of the oil to lubricate. If ethylene glycol is present, it promotes varnish and deposit formation. This test method is designed for early detection to prevent coolant from accumulating and seriously damaging the engine.1.1 This test method covers the determination of ethylene glycol as a contaminant in used engine oil. This test method is designed to quantitate ethylene glycol in the range from 5 mass ppm to 200 mass ppm.1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific warning statements, see Section 7.NOTE 1: A qualitative determination of glycol-base antifreeze is provided in Test Methods D2982. Procedure A is sensitive to about 100 ppm.1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价: 515元 / 折扣价: 438 加购物车

在线阅读 收 藏

5.1 This test method covers the determination of the dissolved gases methane, ethane, ethylene, and propane in drinking, waste, and ground waters, including domestic wells; whether naturally occurring or resulting from commercial activities, dissolved gases can be hazardous both to the environment and humans. Due to increased scrutiny of dissolved gases, developing a valid method for the testing of dissolved gases in water has become more imperative. Static headspace sampling is generally applicable for sampling these compounds. However, as these compounds are extremely volatile, a closed sampling system is recommended. This test method can be used for quantitatively determining dissolved gases in ground, waste, and drinking waters.5.2 This test method is suitable for analysis of domestic drinking water samples from residential and commercial water supply wells prior to oil and gas exploration activities to form a baseline for monitoring potential impacts during exploration; development, including hydraulic fracturing; operation; closure; and reclamation of nearby oil and gas production and injection wells.1.1 This test method covers the determination of the dissolved gases methane, ethane, ethylene, and propane in drinking, waste, and ground waters, including domestic wells whether naturally occurring or resulting from commercial activities, or both. This test method has an analytical range from 10 µg/L to 11 000 µg/L for methane, and 10 µg/L to 5000 µg/L for ethane, ethylene, and propane. If a sample has a dissolved gas concentration above the calibration range, the sample would require dilution. Other analytical ranges may be used as long as the instrument calibration encompasses the desired range and demonstrates adequate linearity.1.2 This test method is applicable to samples collected at a nominal ambient pressure. Samples collected under high pressures, that is, above ambient pressure, may not be accurately analyzed using this method.1.3 This test method is applicable to a variety of dissolved gases; however, for the present standard, only methane, ethane, ethylene, and propane were validated. In order to validate for a gas not listed in this method, the analyst would need to establish the saturation concentration of the new gas, and establish a valid curve, method detection limits, and demonstration of capability following the procedures outlined in this method.1.4 It is the analyst’s responsibility to ensure the validity of this test method for dissolved gases other than methane, ethane, ethylene, and propane and other sample matrices.1.5 Units—The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard.1.6 A single laboratory study was done in order to establish precision and bias for the surrogate (see Section 16).1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价: 646元 / 折扣价: 550 加购物车

在线阅读 收 藏

3.1 Either test method may be used to determine the concentrations of diethylene glycol in ethylene glycol. The concentrations of the components are obtained by a normalization technique, based on the assumption that all components are eluted under the conditions used. If all components should not be eluted, the calculated concentrations will be erroneously high, with the major component showing the most significant absolute error. Since water is not detected by these procedures, the results are on a water-free basis. Water may be determined in accordance with the applicable sections of Test Methods E202 and the gas chromatographic results corrected for the water concentration.3.2 Both test methods are currently in industrial use. Test Method A is the simpler of the two test methods because it does not require the preparation of derivatives prior to gas chromatographic analysis. The results obtained by Test Method A are slightly more accurate than those obtained by Test Method B. With respect to precision there is no significant difference between the two test methods. Test Method B has been reported to be suitable also for the analysis of a wide variety of glycol ethers, but this use is beyond the scope of this standard.1.1 These test methods are intended primarily for the analysis of mixtures of ethylene and diethylene glycols in which the diethylene glycol concentration is 0.1 % or less. Both test methods should be applicable to higher concentrations of diethylene glycol, but precision and bias estimates have been obtained only for 0.05 to 0.1 % diethylene glycol.NOTE 1: Test Methods E202 describe another gas chromatographic test method applicable to mixtures of ethylene, diethylene, and triethylene glycols and mixtures of propylene, dipropylene, and tripropylene glycols in which one of the glycols is the principal component and the other two are present in concentrations of 0.1 to 1 % each.NOTE 2: Test Method E2409 describes another gas chromatographic test method for the determination of glycol impurities in mono-, di-, tri- and tetraethylene glycol (MEG, DEG, TEG and TeEG) in the range of 5 to 3000 μg/g.1.2 The two test methods are given as follows:  SectionsTest Method A—Nonderivative Method 5 to 13Test Method B—Derivative Method 14 to 221.3 Review the current Safety Data Sheets (SDS) for detailed information concerning toxicity, first aid procedures, and safety precautions for chemicals used in this standard.1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard with the exception of foot-pound units for apparatus descriptions.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For a specific warning statement, see 15.1.5.

定价: 0元 / 折扣价: 0

在线阅读 收 藏

4.1 High-purity ethylene is required as a feedstock for some manufacturing processes and the presence of trace amounts of certain hydrocarbon impurities can have deleterious effects. This test method is suitable for setting specifications, for use as an internal quality control tool, and for use in development or research work.4.2 This test method does not detect such impurities as H2O, CO, CO2, and alcohols that may be present in the sample. Hydrocarbons higher than n-decane cannot be analyzed by this test method, if present in the sample. Test Method D2504 addresses the analysis of noncondensable gases and Test Method D2505 addresses the analysis of CO2. Guide D5234 describes all potential impurities present in ethylene. These standards should be consulted when determining the total concentration of impurities in ethylene.1.1 This test method covers the determination of methane, ethane, propane, propene, acetylene, iso-butane, propadiene, butane, trans-2-butene, butene-1, isobutene, cis-2-butene, methyl acetylene and 1,3-butadiene in high-purity ethylene. The purity of the ethylene can be calculated by subtracting the total percentage of all impurities from 100.00 %. Since this test method does not determine all possible impurities such as CO, CO2, H2O, alcohols, nitrogen oxides, and carbonyl sulfide, as well as hydrocarbons higher than decane, additional tests may be necessary to fully characterize the ethylene sample.1.2 Data are reported in this test method as ppmV (parts per million by gaseous volume) and ppmMol (parts per million Mol). This test method was evaluated in an interlaboratory cooperative study in the concentration range of 4 ppmV to 340 ppmV (2 mg/kg to 204 mg/kg). The participants in the interlaboratory cooperative study reported the data in non-SI units. Wherever possible, SI units are included.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价: 590元 / 折扣价: 502 加购物车

在线阅读 收 藏

4.1 This test method provides for the quantitative determination of inorganic chloride (chloride ion) in monoethylene glycol (MEG), diethylene glycol (DEG) and triethylene glycol (TEG) using ion chromatography with conductivity detection. The analysis time is less than 5 min with little or no sample preparation required. Conductivity detection is a universal detection mode and is linear over the range of the method. Acceptable levels of chloride in polyester-grade and low-conductivity-grade MEG vary with the manufacturer’s specifications but are normally in the low mg/kg range. Knowledge of the chloride content in polyester-grade and low-conductivity-grade MEG is required to establish whether the MEG product meets specification requirements.4.2 Glycols have high viscosities and a dilution with high quality deionized water may be required depending on the capability of the autosampler, if used, to deliver the injection. All standards and samples, whether diluted or not should be treated in the same manner.1.1 This test method covers the determination of inorganic chloride (chloride ion) in monoethylene glycol (MEG), diethylene glycol (DEG) and triethylene glycol (TEG) in the range of 0.01 to 1.0 mg/kg by ion chromatography (IC).1.2 Ethylene glycol can be analyzed directly by this test method without any sample preparation or diluted with high quality deionized water if an autosampler is used and dilution is necessary (that is, 50:50 or other suitable ratio).1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3.1 The exception is the additional information of (psi) in 9.3.3, 11.1.1, and 11.2.1.1.4 Review the current Safety Data Sheets (SDS) for detailed information concerning toxicity, first-aid procedures and safety precautions.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Section 9.

定价: 590元 / 折扣价: 502 加购物车

在线阅读 收 藏
ASTM E2470-22 Standard Specification for Polyester Grade Ethylene Glycol Active 发布日期 :  1970-01-01 实施日期 : 

This specification covers polyester grade ethylene glycol. Sampled specimens shall undergo tests, for which the following chemical and physical requirements should be met: acidity (as acetic acid); aldehydes (acetaldehyde) content; appearance; chloride content; color (Pt-Co scale); glycols (as ethylene and diethylene glycol) content; iron content; ultraviolet transmittance; water content; ash content; distillation range (initial boiling point and dry point); relative density; and water miscibility.1.1 This specification covers polyester grade ethylene glycol.1.2 Review the current Safety Data Sheets (SDS) for detailed information concerning toxicity, first aid procedures, handling and safety precautions.1.3 The following applies to all specified limits in this standard; for purposes of determining conformance with this standard, an observed value or a calculated value shall be rounded off “to the nearest unit” in the last right-hand digit used in expressing the specification limit, in accordance with the rounding-off method of Practice E29.1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价: 515元 / 折扣价: 438 加购物车

在线阅读 收 藏

5.1 The inherent viscosity is relatable to the composition and molecular weight of a polyester resin. It must be controlled so that the processability and end properties of the resin remain in a desired range.1.1 This test method is for the determination of the inherent viscosity of poly(ethylene terephthalate) (PET) soluble at 0.50 % concentration in a 60/40 phenol/1,1,2,2-tetrachloroethane solution by means of a glass capillary viscometer. Highly crystalline forms of PET that are not soluble in this solvent mixture will require a different procedure.1.2 The inherent viscosity values obtained by this test method are comparable with those obtained using differential viscometry described in Test Method D5225.1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific hazards statements are given in Section 8.1.4.1 Warning—Mercury has been designated by many regulatory agencies as a hazardous material that can cause serious medical issues. Mercury, or its vapor, has been demonstrated to be hazardous to health and corrosive to materials. Caution should be taken when handling mercury and mercury containing products. See the applicable product Safety Data Sheet (SDS) for additional information. Users should be aware that selling mercury and/or mercury containing products into your state or country may be prohibited by lawNOTE 1: This standard and ISO 1628-5 address the same subject matter, but differ in technical content. This ISO standard gives an option of solvents for PET. Solvent specified in this ASTM test method is one of the options in the ISO method. ISO also uses Type 1C Ubbelohde viscometer, rather than the 1B, and reports viscosity number, rather than inherent viscosity.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价: 515元 / 折扣价: 438 加购物车

在线阅读 收 藏

5.1 Measurements of EO content correlate to polyol reactivity (as related to primary hydroxyl content), linearity of foam rise, and hydrophilicity of the polyol and final product.1.1 Test Method A—Proton Nuclear Magnetic Resonance Spectroscopy (1H NMR) measures polymerized ethylene oxide (EO) content of ethylene oxide (EO) propylene oxide (PO) polyether polyols used in flexible polyurethane foams and non-foams. It is suitable for diols initiated from glycols of EO or PO containing EO percentages >5. For triols initiated with glycerol (glycerin) and trimethylolpropane, an uncorrected EO value is obtained since both initiators have protons that contribute to the EO measurement.1.2 Test Method B—Carbon-13 Nuclear Magnetic Resonance Spectroscopy (13C NMR) measures the polymerized EO content of EO-PO polyether polyols used in flexible polyurethane foams and non-foams. It is suitable for diols and triols made from the commonly used initiators and containing EO percentages >5.1.3 The values stated in SI units are to be regarded as standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.NOTE 1: There is no known ISO equivalent to this standard.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价: 590元 / 折扣价: 502 加购物车

在线阅读 收 藏
49 条记录,每页 15 条,当前第 3 / 4 页 第一页 | 上一页 | 下一页 | 最末页  |     转到第   页