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   96034篇
  免费   933篇
  国内免费   261篇
化学   53720篇
晶体学   1435篇
力学   3805篇
综合类   1篇
数学   10739篇
物理学   27528篇
  2022年   771篇
  2021年   1026篇
  2020年   1195篇
  2019年   1320篇
  2018年   1790篇
  2017年   1850篇
  2016年   2487篇
  2015年   1309篇
  2014年   2055篇
  2013年   4140篇
  2012年   3710篇
  2011年   4366篇
  2010年   3150篇
  2009年   3116篇
  2008年   3931篇
  2007年   3807篇
  2006年   3742篇
  2005年   3381篇
  2004年   3053篇
  2003年   2825篇
  2002年   2884篇
  2001年   2502篇
  2000年   1860篇
  1999年   1437篇
  1998年   1351篇
  1997年   1261篇
  1996年   1170篇
  1995年   1052篇
  1994年   1041篇
  1993年   1001篇
  1992年   1048篇
  1991年   1115篇
  1990年   1039篇
  1989年   1044篇
  1988年   993篇
  1987年   936篇
  1986年   869篇
  1985年   1101篇
  1984年   1224篇
  1983年   1002篇
  1982年   1095篇
  1981年   1006篇
  1980年   958篇
  1979年   1003篇
  1978年   1105篇
  1977年   1115篇
  1976年   1010篇
  1975年   947篇
  1974年   973篇
  1973年   935篇
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
121.
122.
We consider the stationary heat conduction and thermoelasticity problem for a plate that whose lateral surfaces are thermally insulated and which has a slit on whose edges a constant temperature is maintained. The heat conduction problem is solved using a modified logarithmic single-layer potential by reducing it to integral equations.Translated fromMatematicheskie Melody i Fiziko-Mekhanicheskie Polya, Issue 31, 1990, pp. 50–54.  相似文献   
123.
This paper discusses recent trends in the field of reverse engineering, particularly those highlighted at the Second Working Conference on Reverse Engineering, held in July 1995. The trends observed include increased orientation toward tasks, grounding in complex real-world applications, guidance from empirical study, analysis of non-code sources, and increased formalization. The paper also summarizes open research issues and provides pointers to future events and sources of information in this area.  相似文献   
124.
125.
We present here a self consistent theory of small amplitude double layers associated with electrostatic ion cyclotron waves in a plasma containing hot electrons, cold ions and traversed by an ion beam. It has been shown that compressive type of double layers solution exists when θb (beam temperature) < αb (beam concentration) < 1.  相似文献   
126.
The results of a calculation of the characteristics of fluctuations in the absorption of energy of electrons and gamma rays in small sensitive volumes of a material in electronic equilibrium are presented. The calculations were performed by the method developed in [1]. The efficiency and accuracy of the method are demonstrated by comparisons with the experimental results and direct numerical simulation. The experience gained in using the method is analyzed. The main numerical result of this work is a table of coefficients enabling the calculation of the probability of the absorption of energy and the first two moments of the energy absorbed in spherical regions with radii of 1, 2, 4, and 8 m, starting only from the electronic spectrum in these regions, for water absorbers with arbitrary shape and arbitrary electronic or photonic sources with energies up to 1 MeV.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 77–82, February, 1988.  相似文献   
127.
The characteristics of the distribution of magnetization and remagnetization of microsections of the surface in the amorphous alloy Co70Fe5Si10B15, prepared in the form of thin ribbons, were studied by the magnetooptical method. It was found that the magnetization I on the surface of the amorphous ribbon studied was strongly nonuniform. It was established that heat treatment (HT) of the sample leads to the appearance of regions of reversed magnetization in the surface layer of the ribbon, while thermomagnetic annealing reduces the nonuniformity of I. The conservation of the transverse component in the HT sample in fields where the magnitude of the component of magnetization parallel to the length of the ribbon remains virtually unchanged suggested that a domain structure of the magnetization ripple type, owing to the strong microdispersion of the magnetic anisotropy, is realized in this sample.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 89–94, March, 1988.  相似文献   
128.
Majorants of the fractal dimension and of the number of determining modes for unbounded sets, invariant with respect to operators of semigroups of classes 1 and 2, are obtained. They are computed for the Navier-Stokes equations (two- and three-dimensional) under the first boundary condition and under periodicity conditions in the spaces and .Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 163, pp. 105–129, 1987.  相似文献   
129.
I consider some low energy restrictions for a “flipped” left-right symmetric model containing exotic fermions ofE 6 and a right-handedW-boson, all with oddR-parity. The new interactions due toW R-exchange have no significant impact on rare kaon decays, because theW R does not couple tod,s,b quarks. On the other hand,W R exchanges might induce rare processes like \(D - \bar D\) mixing, \(D^0 \to \mu \bar \mu ,D^0 \to \mu \bar e,\mu \to e\gamma ,\mu \to 3e\) , and μNeN. It turns out that the strongest bound is obtained from \(D - \bar D\) mixing. With reasonable extra assumptions, it is found that the exotic right-handed W-boson is likely to be heavier than 500 to 1500 GeV.  相似文献   
130.
The behavior of effective charges i(t) corresponding to the parameters of nonminimal coupling of scalar and gravitational fields in E6 Grand Unification Theory (GUT) in curve spacetimes is studied. It is shown that in a strong gravitational field ¦i(t)¦ grows indefinitely.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 74–11, September, 1990.  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