全文获取类型
收费全文 | 113138篇 |
免费 | 7552篇 |
国内免费 | 6930篇 |
专业分类
化学 | 66178篇 |
晶体学 | 1540篇 |
力学 | 6435篇 |
综合类 | 554篇 |
数学 | 13774篇 |
物理学 | 39139篇 |
出版年
2023年 | 913篇 |
2022年 | 2046篇 |
2021年 | 2528篇 |
2020年 | 2722篇 |
2019年 | 2982篇 |
2018年 | 3332篇 |
2017年 | 3270篇 |
2016年 | 4122篇 |
2015年 | 3088篇 |
2014年 | 4355篇 |
2013年 | 5971篇 |
2012年 | 6181篇 |
2011年 | 6617篇 |
2010年 | 5243篇 |
2009年 | 5295篇 |
2008年 | 5598篇 |
2007年 | 5205篇 |
2006年 | 4791篇 |
2005年 | 4236篇 |
2004年 | 3727篇 |
2003年 | 3259篇 |
2002年 | 3511篇 |
2001年 | 3031篇 |
2000年 | 2393篇 |
1999年 | 1874篇 |
1998年 | 1718篇 |
1997年 | 1468篇 |
1996年 | 1418篇 |
1995年 | 1163篇 |
1994年 | 1234篇 |
1993年 | 1153篇 |
1992年 | 1118篇 |
1991年 | 1170篇 |
1990年 | 1155篇 |
1989年 | 1079篇 |
1988年 | 953篇 |
1987年 | 933篇 |
1986年 | 897篇 |
1985年 | 939篇 |
1984年 | 922篇 |
1983年 | 829篇 |
1982年 | 804篇 |
1979年 | 806篇 |
1978年 | 826篇 |
1977年 | 809篇 |
1976年 | 923篇 |
1975年 | 813篇 |
1974年 | 846篇 |
1973年 | 848篇 |
1972年 | 753篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Ya. Yu. Nikitin 《Journal of Mathematical Sciences》1992,61(1):1891-1896
The local Chernoff efficiency of the sign and Wilcoxon statistics are derived for the testing of symmetry on the basis of the analysis of the probabilities of large deviations of these statistics under the hypothesis and the alternative.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova Akademii Nauk SSSR, Vol. 177, pp. 101–107, 1989. 相似文献
82.
Yu. N. Gordeev 《Fluid Dynamics》1995,30(6):870-876
The initial stage of propagation of a vertical hydraulic fracture in an impermeable or low-permeability stratum is considered within the framework of the pseudo-three-dimensional Perkins-Kern model.Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 6, pp. 79–86, November–December, 1995. 相似文献
83.
S. P. Timoshenko Institute of Mechanics, National Academy of Sciences of the Ukraine. Translated from Prikladnaya Mekhanika, Vol. 31, No. 9, pp. 15–23, September, 1995. 相似文献
84.
E.P. Yelsukov Yu.N. Vorobyov T.I. Arbusova I.B. Smolyak 《Journal of magnetism and magnetic materials》1994,130(1-3):44-50
We have measured the concentration dependence of the average magnetic moment per Fe atom
Fe(x) in microcrystalline and amorphous Fe-P alloys obtained over a wide concentration range using electrochemical deposition. The model of local magnetic moments has been used to described
Fe(x). On the basis of this model the effects of phosphorus on the value
Fe are explained in terms of the parameters of the local environment of the Fe atom. 相似文献
85.
86.
S. A. Chernyak O. V. Shekhter N. L. Sergovskaya Yu. S. Tsizin 《Chemistry of Heterocyclic Compounds》1992,28(7):832-834
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 994–996, July, 1992. 相似文献
87.
Yu. V. Pokonova 《Russian Journal of Applied Chemistry》2007,80(11):1964-1968
Advantage of use residue from thermal cracking and products of its condensation as components of the mixture for manufacturing mechanically rigid (93%) granulated and ground carbon sorbents with extended volume of micropores (up to 0.27 cm3/cm3), showing enhanced sorption activity (E is up to 25.6 kJ mol?1) and high ability of separation various gas mixtures is demonstrated. As a carrier for medicine preparations these adsorbents show higher performance as compared with industrial samples. Solutions of the cracking residue can be used for impregnation of worked out zeolites for petroleum technology and for production of organomineral adsorbents with high adsorption capacity on extraction mercury from sewages. 相似文献
88.
Yu. G. Tselishchev 《Colloid Journal》2007,69(4):537-539
The capillary pressure in a liquid interlayer between two spherical particles is calculated as a function of their sizes and the wetting properties of the liquid. 相似文献
89.
The crystallization behavior of miscible syndiotactic polystyrene (sPS) and atactic polystyrene (aPS) blends with different sPS/aPS weight ratios was investigated in supercritical CO2 by using Fourier‐transform infrared spectroscopy, differential scanning calorimetry, and wide‐angle X‐ray diffraction. Supercritical CO2 and aPS exhibited different effects on the conformational change of sPS and competed with each other. Increasing the content of amorphous aPS in the blends made its effect on the conformational change of sPS gradually surpass that of supercritical CO2. Supercritical CO2 favored the formation of the helical conformation of sPS in lower temperature range and the all trans planar conformation in higher temperature range, instead of forming the latter one only in higher temperature range in ambient atmosphere. However, increasing aPS content in the blends pushed the range for forming the helical conformation to lower temperature and made the all trans planar conformation dominant in aPS/sPS 25/75 blend after treating in supercritical CO2 above 60 °C. The all trans planar zigzag conformation was more favorable than the helical conformation after mixing aPS in sPS in supercritical CO2. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1755–1764, 2007 相似文献
90.
Fengping Yu Junpo He Xiaojun Wang Guangzheng Gao Yuliang Yang 《Journal of polymer science. Part A, Polymer chemistry》2007,45(17):4013-4025
A combination of nitroxide‐mediated radical polymerization and living anionic polymerization was used to synthesize a series of well‐defined graft (co)polymers with “V‐shaped” and “Y‐shaped” branches. The polymer main chain is a copolymer of styrene and p‐chloromethylstyrene (PS‐co‐PCMS) prepared via nitroxide‐mediated radical polymerization. The V‐shaped branches were prepared through coupling reaction of polystyrene macromonomer, carrying 1,1‐diphenylethylene terminus, with polystyryllithium or polyisoprenyllithium. The Y‐shaped branches were prepared throughfurther polymerization initiated by the V‐shaped anions. The obtained branches, carrying a living anion at the middle (V‐shaped) or at the end of the third segment (Y‐shaped), were coupled in situ with pendent benzyl chloride of PS‐co‐PCMS to form the target graft (co)polymers. The purified graft (co)polymers were analyzed by size exclusion chromatography equipped with a multiangle light scattering detector and a viscometer. The result shows that the viscosities and radii of gyration of the branched polymers are remarkably smaller than those of linear polystyrene. In addition, V‐shaped product adopts a more compact conformation in dilute solution than the Y‐shaped analogy. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4013–4025, 2007 相似文献