定价： 515元 / 折扣价： 438 元 加购物车

定价： 515元 / 折扣价： 438 元 加购物车

定价： 515元 / 折扣价： 438 元 加购物车

定价： 0元 / 折扣价： 0 元 加购物车

定价： 646元 / 折扣价： 550 元 加购物车

定价： 0元 / 折扣价： 0 元 加购物车

定价： 515元 / 折扣价： 438 元 加购物车

The use of GaAs for semiconductor devices requires a consistent atomic lattice structure. However, lattice or crystal line defects of various types and quantities are always present, and rarely homogeneously distributed. It is important to determine the mean value and the spatial distribution of the etch pit density.1.1 This test method is used to determine whether an ingot or wafer of gallium arsenide is monocrystalline and, if so, to measure the etch pit density and to judge the nature of crystal imperfections. To the extent possible, it follows the corresponding test method for silicon, Test Method F 47. Test Method F 47 also presents the definition of many crystallographic terms, applicable to this test method. 1.2 This procedure is suitable for gallium arsenide crystals with etch pit densities between 0 and 200 000/cm2. 1.3 Gallium arsenide, either doped or undoped, and with various electrical properties, may be evaluated by this test method. The front surface normal direction of the sample must be parallel to the <001> within ± 5° and must be suitably prepared by polishing or etching, or both. Unremoved processing damage may lead to etch pits, obscuring the quality of the bulk crystal. 1.4 This standard does not purport to address all of the safety problems, 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. Specific hazard statements are given in Section 8.

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5.1 Ambient marine waters generally contain very low concentrations of toxic metals that require sensitive analytical methods, such as ICP-MS, to detect and measure the metal's concentrations.5.2 Due to the high dissolved salt concentrations present in seawater, sample pretreatment is required to remove signal suppression and significant polyatomic interferences due to the matrix both of which compromise detection limits.1.1 Toxic elements may be present in ambient waters and may enter the food chain via uptake by plants and animals; the actual concentrations of toxic metals are usually sub-ng/mL. The U.S. EPA has published its Water Quality Standards in the U.S. Federal Register 40 CFR 131.36, Minimum requirements for water quality standards submission, Ch. I (7-1-00 Edition), see Annex, Table A1.1. The U.S. EPA has also developed Method 1640 to meet these requirements, see Annex, Table A1.2.1.2 Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) is a technique with sufficient sensitivity to routinely measure toxic elements in ambient waters, both fresh and saline (Test Method D5673). However saline and hard water matrices pose analytical challenges for direct multielement analysis by ICP-MS at the required sub-ng/mL levels.1.3 This practice describes a method used to prepare water samples for subsequent multielement analysis using ICP-MS. The practice is applicable to seawater and fresh water matrices, which may be filtered or digested. Samples prepared by this method have been analyzed by ICP-MS for the elements listed in Annex, Table A1.3).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： 590元 / 折扣价： 502 元 加购物车

This test method provides a means of evaluating and comparing development of corrosion at scribe on painted/coated flat test panels after exposure to corrosive environments.1.1 This test method covers the measurement of rust creepage area from a scribe line on painted/coated flat test panels after exposure to corrosive environments. This test method has the advantage of simplicity and ease of use. Expensive equipment is not required, and the results are more accurate than visual evaluation but not as precise as advanced digital imaging. 1.2 This test method uses visual imaging software to determine the area damaged by rust creepage from the scribe. 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.

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This guide is intended for use in any laboratory utilizing PCR or RT-PCR to amplify and detect nucleic acid sequences of mycobacteria from a biological preparation and to identify the species of origin.The criteria used for the identification and evaluation of the amplification reactions should be administered by an individual trained in the use of molecular biological and microbiological techniques associated with PCR and MTB.1.1 This guide covers basic considerations, criteria, principles and recommendations that should be helpful when developing, utilizing, or assessing PCR-specific protocols for the amplification and detection or identification of mycobacterial nucleic acids. This guide is not a specific protocol for the detection of specific mycobacteria. It is intended to provide information that will assist the user in obtaining high quality and reliable data. The guide is closely related to and should be used concurrently with the general PCR Guide E 1873.1.2 This guide has been developed for use in any molecular biology or biotechnology laboratory. It may be useful for the detection of mycobacteria in clinical, diagnostic laboratories.1.3 This guide does not cover details of the various methods such as gel electrophoresis that can be utilized to help identify PCR-amplified mycobacterial nucleic acid sequences, and it does not cover details of instrument calibration.1.4 This guide does not cover specific variations of the basic PCR or RT-PCR technology (for example, quantitative PCR, multiplex PCR and in situ PCR), and it does not cover details of instrument calibration.1.5 Warning-Laboratory work involving certain clinical specimens and microorganisms can be hazardous to personnel. Precaution: Biosafety Level 2 facilities are recommended for potentially hazardous work, and Biosafety Level 3 facilities are required for propagating and manipulating Mycobacteria tuberculosis cultures (). Safety guidelines should be adhered to according to NCCLS M29-T2, I17-P and other recommendations ().

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定价： 590元 / 折扣价： 502 元 加购物车

定价： 590元 / 折扣价： 502 元 加购物车

3.1 The GESD procedure can be used to simultaneously identify up to a pre-determined number of outliers (r) in a data set, without having to pre-examine the data set and make a priori decisions as to the location and number of potential outliers.3.2 The GESD procedure is robust to masking. Masking describes the phenomenon where the existence of multiple outliers can prevent an outlier identification procedure from declaring any of the observations in a data set to be outliers.3.3 The GESD procedure is automation-friendly, and hence can easily be programmed as automated computer algorithms.1.1 This practice provides a step by step procedure for the application of the Generalized Extreme Studentized Deviate (GESD) Many-Outlier Procedure to simultaneously identify multiple outliers in a data set. (See Bibliography.)1.2 This practice is applicable to a data set comprising observations that is represented on a continuous numerical scale.1.3 This practice is applicable to a data set comprising a minimum of six observations.1.4 This practice is applicable to a data set where the normal (Gaussian) model is reasonably adequate for the distributional representation of the observations in the data set.1.5 The probability of false identification of outliers associated with the decision criteria set by this practice is 0.01.1.6 It is recommended that the execution of this practice be conducted under the guidance of personnel familiar with the statistical principles and assumptions associated with the GESD technique.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： 590元 / 折扣价： 502 元 加购物车

3.1 This practice establishes a multiple person cold water survival/rescue procedure.3.2 All persons who are identified as water rescuers shall meet the requirements of this practice.3.3 This practice is intended to assist government agencies, state, local, or regional organizations; fire departments; and rescue teams and others who are responsible for establishing a minimum performance for personnel who respond to water emergencies.3.4 The majority of the rescuers performing this technique must be wearing personal flotation devices. These devices should conform to standards set by the appropriate national regulatory authority, that is, the U.S. Coast Guard in the United States, and be in good and serviceable condition.3.5 A water rescuer sometimes may be immersed in cold water for prolonged periods of time. They are unable to get to shore or shore is too far away, rescue is not imminent, no boat is available to get into or on top of, and no flotsam is available. The water rescuer needs to assume a defensive posture to conserve heat and increase survival time.1.1 This practice covers the recommended water rescue procedure for performing the huddle position.1.2 This practice is one in a set of self-rescue techniques for the water rescuer.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： 515元 / 折扣价： 438 元 加购物车