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881.
激光光束传输因子M2的一些问题 总被引:7,自引:4,他引:3
本文讨论与M2因子有关的一些问题,指出在近轴近似条件下由光束的二阶强度矩定义的M2因子满足M2≥1,其中只有对基模高斯光束等式才成立.由光束的功率通量值定义的M2因子(Mpc2)有可能小于1,Mpc2的大小取决于所定义的光斑半径内包含的光功率的百分数.通过计算光场的二阶矩,我们获得了轴向相干叠加的高斯光束的M2因子的解析解. 相似文献
882.
发动机润滑油老化及检测方法 总被引:1,自引:0,他引:1
发动机润滑油老化后会增加发动机磨损 ,缩短发动机使用寿命。检测机油品质时可用理化性能指标检测法及经验判断法。而经验判断对运输企业及维修企业更实用 相似文献
883.
重视物理实验教学中的创新能力培养和科学素质教育 总被引:4,自引:0,他引:4
通过分析物理学的教育功能和文化价值 ,阐述了物理实验教学中加强学生能力培养和科学素质教育的优势和做法。 相似文献
884.
探讨制定物理教学仪器标准应遵循的原则 总被引:1,自引:0,他引:1
教学仪器的标准是保障教学仪器为教学服务的准绳,是教学仪器技术性能的基础。本文从物理教学仪器的教育功能出发,研究、探讨制订物理教学仪器标准应遵循的原则。 相似文献
885.
激光光束传输因子M~2的一些问题 总被引:3,自引:0,他引:3
本文讨论与 M2 因子有关的一些问题 ,指出在近轴近似条件下由光束的二阶强度矩定义的 M2 因子满足 M2 ≥ 1 ,其中只有对基模高斯光束等式才成立 .由光束的功率通量值定义的 M2 因子 ( M2pc)有可能小于 1 ,M2pc的大小取决于所定义的光斑半径内包含的光功率的百分数 .通过计算光场的二阶矩 ,我们获得了轴向相干叠加的高斯光束的 M2 因子的解析解 相似文献
886.
This paper studies the relationship between product quality as defined by tolerances on the product to tolerances on the parts. All the standard sure-fit and the statistical-fit tolerancing models, which seek to find the least cost tolerances for the parts given the product specification, are found to be convex. Thus conjugate duality provides a unifying framework for studying the relationship between quality and tolerancing and the analysis and solution of such problems. Moreover this convexity is maintained even with the addition of quality loss functions. Quality loss is modeled on the basis of parts or the product. The analysis leads to an analytic solution to a number of models including the quality loss model. 相似文献
887.
Dean A. Flinchbaugh L. F. Crawford David Bradley 《Accreditation and quality assurance》2001,6(12):493-500
A model is presented that correlates historical proficiency test data as the log of interlaboratory standard deviations versus
the log of analyte concentrations, independent of analyte (measurand) or matrix. Analytical chemistry laboratories can use
this model to set their internal measurement quality objectives and to apply the uncertainty budget process to assign the
maximum allowable variation in each major step in their bias-free measurement systems. Laboratories that are compliant with
this model are able to pass future proficiency tests and demonstrate competence to laboratory clients and ISO 17025 accreditation
bodies. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/
10.1007/s007690100398-y.
Received: 31 March 2001 Accepted: 11 September 2001 相似文献
888.
N. P. Boley Paul De Bièvre Philip D. P. Taylor Adam Uldall 《Accreditation and quality assurance》2001,6(6):244-251
Many laboratories take part in proficiency testing schemes, external quality assessment programmes and other interlaboratory
comparisons. These have many similarities but also important differences in their modus operandi and evaluation of performance of participating laboratories. This paper attempts to highlight both the similarities and differences. It also puts particular emphasis on requirements
called ”target values for uncertainty” and their meaning.
Received: 24 January 2001 Accepted: 25 January 2001 相似文献
889.
Yuri A. Karpov Natella A. Arakelian V. E. Kvin Vasilisa B. Baranovskaya Tatyana Yu Alekseeva V. P. Obresumov Lyudmila P. Zhitenko 《Accreditation and quality assurance》2001,6(2):66-71
Our experience of executing proficiency testing programs on the analysis of precious metals and precious metal bearing materials
is summarized. Six proficiency testing programs of the ”distributed sample testing” type were carried out using samples essentially
distinct from each other: (I) certified samples of fine gold and fine silver, and (II) recoverable raw (scrap and catalyst
waste) containing precious metals of unknown contents. The test results were assessed using the London Bullion Market Association
(LBMA) rules and by Z-criteria using the ISO/IEC Guide 43 scale. Satisfactory results were presented by all participants for the analysis of certified
samples of fine gold and fine silver. The results of catalyst waste analysis agreed rather well, whereas the scrap analysis
revealed an essential discrepancy in the data for some samples. The reasons for such discrepancies are discussed.
Received: 9 June 2000 Accepted: 21 November 2000 相似文献
890.
Five solid complexes of zinc with L‐α‐methionine, L‐α‐phenylalanine and L‐α‐histidine were prepared. The constant‐volume combustion energies of the complexes, ΔEc (coordination), were determined by a precise rotating bomb calorimeter at 298.15 K. They were ‐ 2969.03 ± 0.34, ‐2929.46 ± 1.59, ‐9597.13 ± 6.12, ‐4378.98 ± 3.27 and ‐14047 ± 6.75 kJ/mol, respectively. Their standard enthalpies of combustion, ΔHθm,c(coordination, s, 298.15 K), and standard enthalpies of formation, ΔHθm,f (coordination, s, 298.15 K), were calculated. They were ‐2959.73 ± 0.34, ‐2923.88 ± 1.59, ‐9649.18 ± 6.12, ‐4373.40 ± 3.27, ‐14048.53 ± 6.75 kj/mol and ‐1180.94 ± 0.92, ‐1401.26 ± 1.77, ‐2501.69 ± 6.50, ‐1381.47 ± 3.49, ‐1950.19 ± 7.65 kJ/mol, respectively. 相似文献