首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   20797篇
  免费   292篇
  国内免费   301篇
化学   11590篇
晶体学   150篇
力学   1457篇
综合类   17篇
数学   2804篇
物理学   5372篇
  2021年   239篇
  2020年   298篇
  2019年   355篇
  2018年   437篇
  2017年   416篇
  2016年   544篇
  2015年   280篇
  2014年   464篇
  2013年   698篇
  2012年   610篇
  2011年   664篇
  2010年   653篇
  2009年   627篇
  2008年   641篇
  2007年   674篇
  2006年   536篇
  2005年   468篇
  2004年   456篇
  2003年   475篇
  2002年   546篇
  2001年   499篇
  2000年   354篇
  1999年   279篇
  1998年   250篇
  1997年   246篇
  1993年   246篇
  1992年   252篇
  1991年   265篇
  1990年   277篇
  1989年   273篇
  1987年   249篇
  1985年   285篇
  1984年   292篇
  1983年   269篇
  1982年   280篇
  1981年   258篇
  1980年   271篇
  1979年   314篇
  1978年   333篇
  1977年   328篇
  1976年   416篇
  1975年   373篇
  1974年   406篇
  1973年   410篇
  1972年   388篇
  1971年   339篇
  1970年   319篇
  1969年   301篇
  1968年   257篇
  1967年   258篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Using the relations of the improved model of layered anisotropic shells based on the straight line assumption taking account of the thermal compression over the thickness we obtain a resolvent system of equations for shells whose properties depend on temperature. We carry out a study of the stresses in a two-layer cylindrical shell formed by winding as a function of the winding angle. Translated fromMatematicheskie Metody i Fiziko-Mekhanicheskie Polya, Issue 35, 1992, pp. 82–85.  相似文献   
32.
33.
Translated fromAlgebra i Logika, Vol. 32, No. 3, pp. 288–307, May–June, 1993.  相似文献   
34.
Translated fromIssledovaniya po Prikladnoi Matematike, No. 19, 1992, pp. 24–33.  相似文献   
35.
A gas-discharge gold-vapor laser on self-terminating transitions with operating wavelength λ=312.2 nm has been used to develop a highly efficient system for image transfer. An optical scheme and all its parameters have been chosen optimal for image quality. It has been found both theoretically and experimentally that the best results on micron-structure image transfer are obtained with 2–5-times image reduction. Various types of masks have been used. A 1-µm structure has been resolved due to the choice of optimal exposure time of 10 ms under a period of pulse repetition (0.6 – 0.8) ms; in this case, the minimal fringe dimension was ≈2 µm with an image dimension of 2 mm for a laser tube 1.8 cm in diameter.  相似文献   
36.
Gal'tsov et al. [Vestn. Mosk. Gos. Univ., Fiz., Astron.,14, No. 5, 614 (1973)] studied the radiation spectrum of N equally spaced charges moving along a circle. In particular, it was shown that as N the intensity of the radiation from the system of charges vanishes. The present study will consider the radiation spectrum of N charges moving along an arbitrary closed curve, randomly distributed in the vicinity of equally spaced points. The coherency factor will be found for the assumption that: a) the distributions of individual charges are not intercorrelated; b) the charge distribution is such that in the vicinity of a given point only one charge is found. It will be shown that as N the radiation intensity tends to a finite limit.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 8–11, March, 1988.  相似文献   
37.
We investigate representations of classical noncompact Lie groups induced by representations of the maximal parabolic subgroup. Formulas are obtained for 5O0(2p, 2q)/U(p, q) and U(2p, 2q) Sp(p, q).Translated from Ukrainskii Mathematicheskii Zhurnal, Vol. 42, No. 1, pp. 128–131, January, 1990.  相似文献   
38.
39.
The rough asymptotic behavior of the probability of large deviations is found for Watson-Darling goodness-of-fit tests, which are centered versions of Kolomogorov-Smirnov statistics. Their Bahadur effectiveness is calculated and conditions for local asymptotic optimality for the alternative of translation are studied.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 158, pp. 138–145, 1987.  相似文献   
40.
2-Methylamino-4,4-disubstituted-5-carboethoxymethyl-2-1,3,4-oxadiazolin -4-ium chlorides were obtained from the reaction of 1,1-disubstituted-4-methylsemicarbazides with ethyl propiolate in the presence of hydrochloric acid. After hydrolysis of the ester these chlorides recyclize in acetic anhydride to 1-substituted-3-acetoxy-1H-pyrazoles. The difference in the direction of ring opening with acetic anhydride in the betaines of 1,3,4-oxadiazolin-5-acetic acids and their thia-analogs has been demonstrated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1685–1688, 1992.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号