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

1.1 This specification covers average or minimum wall thickness electric resistance welded (ERW) tubing to be used for boilers, heat exchangers, condensers, and similar heat-transfer apparatus.1.2 The tubing sizes and thicknesses usually furnished to the specification are 0.375 in. [9.5 mm] inside diameter (ID) to 1.5 in. [38 mm] outside diameter (OD) and 0.020 to 0.079 in. [0.5 to 2 mm], inclusive, in wall thickness. Tubing having other dimensions may be furnished provided such tubes comply with all other requirements of this specification.1.3 The steel materials shall have the (1) external tube surface, (2) internal tube surface, or (3) both internal and external tube surfaces textured to improve heat transfer or fluid flow or both. Textured surface(s) are produced by cold forming a specified configuration on the surface(s) of base strip material before welding.1.4 Optional supplementary requirements are provided and, when desired, shall be so stated on the purchase order.1.5 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard. The inch-pound units shall apply unless the “M” designation (SI) of the product specification is specified in the order.1.6 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.1.7 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

This specification covers seamless and electric-resistance-welded steel pipe used as conduit for the installation of high-pressure pipe-type electrical cables in NPS 4 to NPS 12, inclusive, with nominal (average) wall thicknesses 0.219 to 0.562 in., depending on size. The steel shall be made by one or more of the following processes: open-hearth, basic-oxygen, or electric-furnace. Tensile strength tests, flattening test, hydrostatic tests shall be made for the materials to conform the requirements as specified. If the results of the mechanical tests do not conform to requirements specified, retests shall be made.1.1 This specification covers two types, seamless (S) and electric-resistance-welded (E), of steel pipe used as conduit for the installation of high-pressure pipe-type electrical cables in NPS 4 to NPS 12 [DN 100 to DN 300], inclusive, with nominal (average) wall thicknesses 0.219 to 0.562 in. [5.56 to 14.27 mm], depending on size. Pipe having other dimensions (Note 2) may be furnished, provided such pipe complies with all other requirements of this specification.NOTE 1: The dimensionless designator NPS (nominal pipe size) has been substituted in this standard for such traditional terms as “nominal diameter,” “size,” and “nominal size.”NOTE 2: A comprehensive listing of standardized pipe dimensions is contained in ASME B36.10.1.2 Pipe ordered under this specification is suitable for welding and for forming operations involving flaring, belling, and bending.1.3 Pipe for this purpose shall be furnished in Grade A or Grade B as specified in the purchase order. Grade A is more suitable for forming operations involving bending, flaring, or belling and this grade is normally preferred. This provision is not intended to prohibit the cold bending, flaring, or belling of Grade B pipe.1.4 This specification is expressed in both inch-pound units and in SI units; however, unless the purchase order or contract specifies the applicable M specification designation (SI units), the inch-pound units shall apply. The values stated in either inch-pound or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system may not be exact equivalents; therefore each system shall be used independently of the other. Combining values from the two systems may results in nonconformance with the standard.1.5 The following hazard caveat applies to the test method portion, Section 20, of this specification: 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: 590元 / 折扣价: 502 加购物车

在线阅读 收 藏

This specification covers two grades of electric-resistance-welded steel pipe intended for conveying gas, vapor, water or other liquid. The steel shall be made by either or both basic-oxygen or electric-furnace processes. Steel may be cast in ingots or may be strand cast. The pipe shall be manufactured from flat rolled steel in individual lengths or continuous length by electric-resistance or electric-induction welding without the addition of extraneous material. The weld seam of electric-resistance welded pipe to Grade B pipe shall be heat treated after welding or processed in such a manner that no untempered martensite remains. Tensile and chemical requirements of the steel are provided. Specimens of the steel pipes are subject to flattening test and hydrostatic test. A nondestructive electric test, either electromagnetic (eddy current) or ultrasonic test, may be preferred as an alternate to the hydrostatic test.1.1 This specification2 covers two grades of electric-resistance-welded steel pipe in NPS 2 to NPS 30 [DN 50 to DN 750] inclusive, with nominal (average) wall thickness up to 0.500 in. [12.70 mm], inclusive, and in nominal sizes NPS 3/4 to NPS 5 [DN 20 to DN 125] inclusive with nominal (average) wall thickness 0.083 in. [2.11 mm] to 0.134 in. [3.40 mm], depending on size. Pipe having other dimensions (Note 1) may be furnished provided such pipe complies with all other requirements of this specification. The pipe is intended for conveying gas, vapor, water or other liquid; only Grade A is adapted for flanging and bending (Note 2). The suitability of pipe for various purposes is somewhat dependent upon its dimensions, properties, and conditions of service, so that the purpose for which the pipe is intended should be stated in the order. The pipe may be furnished either nonexpanded or cold expanded at the option of the manufacturer. When pipe is cold expanded, the amount of expansion shall not exceed 1.5 % of the outside diameter pipe size.NOTE 1: A comprehensive listing of standardized pipe dimensions is contained in ASME B36.10M.NOTE 2: This provision is not intended to prohibit the cold bending of Grade B pipe.1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.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: 590元 / 折扣价: 502 加购物车

在线阅读 收 藏

This specification covers five grades of electric-fusion(arc)-welded straight-seam or helical steel pipe including pipe of NPS 4 and over. The required chemical composition, tensile requirements of the steel, and the tensile requirements of the production welds are presented. Heat analysis of each heat of steel was made to determine the percentage of the elements as per chemical requirements. Tests to be performed shall include one longitudinal tension test for the steel, one reduced-section production weld test for the pipe, and hydrostatic test for each length of the pipe.1.1 This specification covers five grades of electric-fusion (arc)-welded straight-seam or helical-seam steel pipe. Pipe of NPS 4 (Note 1) and larger with nominal (average) wall thickness of 1.0 in. [25.4 mm] and less are covered. Listing of standardized dimensions are for reference (Note 2). The grades of steel are pipe mill grades having mechanical properties which differ from standard plate grades. The pipe is intended for conveying liquid, gas, or vapor.NOTE 1: The dimensionless designator NPS (nominal pipe size) has been substituted in this standard for such traditional terms as “nominal diameter,” “size,” and “nominal size.”NOTE 2: A comprehensive listing of standardized pipe dimensions is contained in ASME B36.10M.NOTE 3: The suitability of pipe for various purposes is somewhat dependent on its dimensions, properties, and conditions of service. For example, for high-temperature service see applicable codes and Specification A691.1.2 This specification is expressed in both inch-pound units and in SI units; however, unless the purchase order or contract specifies the applicable M specification designation (SI units), the inch-pound units shall apply. The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.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: 590元 / 折扣价: 502 加购物车

在线阅读 收 藏

1. Scope This clause of IEC Publication 335-1 is applicable except as follows: 1.1 Replacement: This standard applies to electric fans and their associated regulators intended for use on single-phase a.c. and d.c. circuits not e xceeding 250 V,

定价: 455元 / 折扣价: 387

在线阅读 收 藏
ASTM F1568-12(2023) Standard Specification for Food Processors, Electric Active 发布日期 :  1970-01-01 实施日期 : 

This specification covers commercial food processors intended for bench, table, or floor mounting. Types: type I - this machine shall have a hopper of the continuous, manual-feed type, and type II - this machine shall have a closed-bowl type of hopper. Classes: class 1 - table- or bench-mounted food processor, and class 2 - floor-mounted food processor. Interlock integrity test, plate stopping time test, type I food processor operation tests, type II food processor operation test, motor performance test, power transmission test, and sound level test shall be performed to meet the requirements prescribed.1.1 This specification covers commercial food processors intended for bench, table, or floor mounting.1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.1.3 The following safety hazards caveat pertains only to the test methods portion, Section 9, of this specification: 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

This specification covers standards for electric-resistance-welded tubes with minimum-wall-thickness made of carbon steel and carbon-manganese steel to be used in boiler tubes, boiler flues, superheater flues, and safe ends. The steel shall be of Grades A (low-carbon steel), C (medium-carbon steel), or D (carbon-manganese steel). All tubes shall be submitted to heat treatment after welding, followed by cooling. The steel shall conform to stated compositions of carbon, manganese, phosphorus, sulphur, and silicon. Grades C and D shall conform to given tensile requirements, that is tensile strength, yield strength, and elongation. The material shall also be subjected to flattening, flange, tension, reverse flattening, and hydrostatic (or nondestructive electric) tests. Crush test shall also be performed if asked by the purchaser. Minimum elongation values are also given.1.1 This specification2 covers minimum-wall-thickness, electric-resistance-welded tubes made of carbon steel and carbon-manganese steel intended for use as boiler tubes, boiler flues, superheater flues, and safe ends.1.2 This specification covers Grades A, C, and D with differing chemical requirements (Section 6 and Table 1), differing tensile requirements (Section 9 and Table 2), and differing crush and mechanical testing requirements (Sections 10 and 11).NOTE 1: Grades C and D tubes are not suitable for safe-ending for forge welding.1.3 The tubing sizes and thicknesses usually furnished to this specification are 1/2 to 5 in. [12.7 to 127 mm] in outside diameter and 0.035 to 0.360 in. [0.9 to 9.1 mm], inclusive, in minimum wall thickness. Tubing having other dimensions may be furnished, provided such tubes comply with all other requirements of this specification.1.4 Mechanical property requirements do not apply to tubing smaller than 1/8 in. [3.2 mm] in inside diameter or 0.015 in. [0.4 mm] in thickness.1.5 Optional supplementary requirements are provided and when desired, shall be so stated in the order.1.6 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification. The inch-pound units shall apply unless the “M” designation of this specification is specified in the order.1.7 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

1.1 This specification covers minimum requirements for the design of electric engines.1.2 Distributed propulsion is not excluded; however, additional requirements will be needed to address the additional issues that distributed propulsion can create. Some of those issues may include: use of a common motor controller/inverter, segregated electric harnesses, cooling systems, electric power supplies, and others.1.3 This specification does not address all of the requirements that may be necessary for possible hybrid configurations where an electric engine and a combustion engine drive a common thruster. This specification may be used for the electric engine aspects with supplemental requirements for the thruster and the combustion engine.1.4 Although this specification does not include specific requirements for electric engines that include gearboxes, thrusters, or any energy storage systems, it also does not preclude such capabilities. This specification may be used for the base electric engine aspects of the design, with supplemental requirements for any additional features prepared by the manufacturer and submitted to the Civil Airworthiness Authority for acceptance. This version of this ASTM specification also does not address all of the requirements necessary for configurations of motor driven ducted-fans. It is anticipated that the fan would be subject to parts of 14 CFR 33 or CS-E and/or 14 CFR 35 or CS-P, or equivalent, in particular blade-off and bird strike. These would be conducted on the fan as a unit (including motor) rather than on motor or fan alone.1.5 The applicant for a design approval should seek the individual guidance of their respective civil aviation authority (CAA) body concerning the use of this specification as part of a certification plan. For information on which CAA regulatory bodies have accepted this specification (in whole or in part) as a means of compliance to their general aviation aircraft airworthiness regulations (hereinafter referred to as “the Rules”), refer to ASTM Committee F39 webpage (www.ASTM.org/COMITTEE/F39.htm), which includes CAA website links.1.6 When applicable, this specification may be used for electric engines with a fixed-pitch propeller or fan. These configurations may be type-certificated as an electric engine including a thruster. There may be additional requirements not currently included in this specification for this type configuration. In addition, 5.25 is included as a test requirement for the electric engine. That section recognizes that when the electric engine does not have an integral thruster it will need to be tested with a representative load on the drive shaft to ensure the engine’s ability to operate properly with static and dynamic loads.1.7 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.1.8 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.1.9 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

CSA Preface This is the second edition of CAN/CSA-E60335-2-76, Household and similar electrical appliances - Safety - Part 2-76: Particular requirements for electric fence energizers, which is an adoption, with Canadian deviations, of the identically titl

定价: 1502元 / 折扣价: 1277

在线阅读 收 藏

This specification applies to the electrical systems, electrical equipment, and electrical power distribution aspects of airworthiness and design for aircraft with electric or hybrid-electric propulsion. Developed through open consensus of international experts in general aviation, this material focused on Normal Category Airplanes. The content may be more broadly applicable; it is the responsibility of the applicant to substantiate broader applicability as a specific means of compliance.This specification establishes the Aircraft Type Code (ATC) compliance matrix based on certification level, number of engines, type of engine(s), stall speed, cruise speed, meteorological conditions, altitude, and maneuvers. An ATC is defined by taking into account both the technical considerations regarding the design of the aircraft and the airworthiness level established based upon risk-based criteria. Requirements for electrical systems for electric propulsion cover power source capacity and distribution, electrical systems and equipment, circuit protective devices, master switch arrangement, switches, electrical cables and equipment, electrical system fire protection, electronic equipment, and storage battery design and installation.1.1 This specification covers the electrical systems, electrical equipment, and electrical power distribution aspects of airworthiness and design for aircraft with Electric or Hybrid-Electric Propulsion. This specification was written with the focus on electric propulsion systems with conventional system layout, characteristics, and operation. This specification does not address all of the requirements that may be necessary for possible hybrid-electric configurations where an EPU and a combustion engine are used in combination to provide propulsion. The use of this specification combined with the applicable portions of Specification F3231/F3231M may be necessary for hybrid-electric configurations. This material was developed through open consensus of international experts in general aviation. This material was created by focusing on Normal Category Aeroplanes. The content may be more broadly applicable; it is the responsibility of the applicant to substantiate broader applicability as a specific means of compliance.1.2 An applicant intending to propose this information as a means of compliance for design approval shall seek guidance from their respective oversight authority (for example, published guidance from applicable CAAs) concerning the acceptable use and application thereof. For information on which oversight authorities have accepted this standard (in whole or in part) as a Means of Compliance to their regulatory requirements (Hereinafter referred to as “the Rules”), refer to ASTM F44 webpage (www.ASTM.org/COMMITTEE/F44.htm).1.3 Units—This standard may present information in either SI units, English Engineering units, or both. 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

1.1 This specification covers one grade of electric-resistance-welded coiled steel tubing 2 3/8 in. (60.3 mm) and under in outside diameter and 0.035 to 0.125 in. (0.89 to 3.18 mm), inclusive, in average wall thickness. The tubing is intended for conveyance of gas and fuel oil.1.2 The values stated in inch-pound units are to be regarded as the standard.

定价: 0元 / 折扣价: 0

在线阅读 收 藏

1. Scope This clause of Part 1 is applicable except as follows: 1.1 Replacement This standard applies to electrically operated commercial water boilers and liquid heaters for the boiling or heating of liquids to be used in the preparation of bev

定价: 637元 / 折扣价: 542

在线阅读 收 藏

This specification covers electric-fusion (arc)-welded straight seam or spiral seam steel pipes with diameters NPS 16 and larger. The materials for these pipes as well as the welding procedure shall conform to other ASTM standards listed herein. This standard also contains requirements for the permissible weight and dimension variations and pipe lengths.1.1 This specification covers electric-fusion (arc)-welded straight seam or spiral seam steel pipe NPS 16 and over in diameter (inside or outside as specified by purchaser), with wall thicknesses up to 3/4 in. [19 mm], inclusive. Pipe having other dimensions may be furnished provided such pipe complies with all other requirements of this specification. The pipe is available in various grades based on the ASTM specification ordered (Section 4).NOTE 1: Acceptability for many services may be controlled by codes or standards such as those published by the American National Standards Institute and American Society of Mechanical Engineers.NOTE 2: For testing methods not specifically covered in this specification, reference can be made to Test Methods and Definitions A370, with particular reference to Annex A2 on Steel Tubular Products.NOTE 3: A comprehensive listing of standardized pipe dimensions is contained in ANSI B 36.10.1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. The inch-pound units shall apply unless the “M” designation of this specification is specified in the order. In this specification hard or rationalized conversions apply to diameter, lengths, and tensile properties. Soft conversion applies to other SI measurements.NOTE 4: The dimensionless designator NPS (nominal pipe size) has been substituted in this standard for such traditional terms as “nominal diameter,” “size,” and “nominal size.”1.3 The following caveat pertains specifically to Section 5 of this specification. 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

AbstractThese specifications cover the equipment making up the temporary grounding system used on de-energized electric power lines, electric supply stations, and equipment. These specifications for a system of protective grounding utilizing copper cables are covered in four parts, as follows: clamps, ferrules, cables, and temporary protective grounds. Each of the four parts is an entity of itself, but is listed as a part of the system for completeness and clarification. The clamps shall be subject to design tests for determining mechanical torque strength and electrical short circuit capacity. The ferrules shall be tested for electrical short-circuit capacity and continuous current rating. The elastomer or thermoplastic making up the jacket of the flexible cable shall be tested according to the specified methods.1.1 These specifications cover the equipment making up the temporary grounding system used on de-energized electric power lines, electric supply stations, and equipment.1.2 It is common practice for the users of protective grounding equipment to prepare complete instructions and regulations to govern in detail the correct use and maintenance of such equipment.1.3 The uses and maintenance of this equipment are beyond the scope of these specifications.1.4 These specifications for a system of protective grounding utilizing copper cables are covered in four parts, as follows:         SectionsClamps for Temporary Protective Grounds   4 – 16Ferrules for Temporary Protective Grounds   17 – 30Cables for Temporary Protective Grounds   31 – 39Protective Grounds (Complete Assembly With Clamps, Ferrules,   and Cable)   40 – 521.5 Each of the four parts is an entity of itself, but is listed as a part of the system for completeness and clarification.1.6 Currents presented in Table 1 are based upon cable melting times, as determined from equations by I. M. Onderdonk and are to used in situations involving an asymmetry value less than 20 % (X/R ≤ 1.8). See Appendix X1.NOTE 1: TPG testing is done on complete assemblies. Assembly ratings assume the grade of lowest graded component (see 43.1.6).1.6.1 Currents presented in Table 2 are based upon the values from EPRI Project RP2446 Computer Program RTGC “A Desktop Computer Program for Calculating Rating of Temporary Grounding Cables” and are to be used in situations involving an asymmetry value greater than 20 % (X/R ≧ 1.8), see Appendix X2.NOTE 1: The above current values are based on electromechanical test values.NOTE 2: Assemblies that have been subjected to these shall not be re-used.NOTE 3: For use with currents exceeding 20 % asymmetry factor.NOTE 4: See X2.7.2 for additional information.NOTE 5: Alternate testing circuits are available for laboratories that cannot achieve the above requirements. See Appendix X2 for details.NOTE 1: Table 1 represents the clamp and assembly ratings that existed prior to this revision. Table 2 represents new ratings now required for high X/R situations.1.6.2 See Appendix X1 and Appendix X2 for a discussion of these topics.1.7 The values stated in Newton-Meter units are to be regarded as the standard. The values in parentheses are the inch-pound units.1.8 The following precautionary caveat pertains to the test method portions, Sections 12 and 25 of these specifications: 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.1.9 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

1. Scope 1.1 This Standard outlines the principles and general practices of electrical protection applicable to overhead supply systems operating at more than 750 V but less than 50 kV phase to phase and communications systems, where the lines of th

定价: 592元 / 折扣价: 504

在线阅读 收 藏
193 条记录,每页 15 条,当前第 12 / 13 页 第一页 | 上一页 | 下一页 | 最末页  |     转到第   页