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   261074篇
  免费   3569篇
  国内免费   1579篇
化学   141243篇
晶体学   3175篇
力学   10455篇
综合类   64篇
数学   35892篇
物理学   75393篇
  2020年   2008篇
  2019年   2145篇
  2018年   3948篇
  2017年   4222篇
  2016年   4964篇
  2015年   3401篇
  2014年   4465篇
  2013年   10468篇
  2012年   11496篇
  2011年   12481篇
  2010年   8775篇
  2009年   8332篇
  2008年   10133篇
  2007年   10283篇
  2006年   9680篇
  2005年   12539篇
  2004年   11118篇
  2003年   8692篇
  2002年   6851篇
  2001年   7222篇
  2000年   5419篇
  1999年   3999篇
  1998年   3290篇
  1997年   3204篇
  1996年   3229篇
  1995年   2793篇
  1994年   2910篇
  1993年   2736篇
  1992年   3101篇
  1991年   3141篇
  1990年   2941篇
  1989年   2737篇
  1988年   2687篇
  1987年   2599篇
  1986年   2590篇
  1985年   3415篇
  1984年   3477篇
  1983年   2879篇
  1982年   3116篇
  1981年   2890篇
  1980年   2684篇
  1979年   2853篇
  1978年   3063篇
  1977年   3103篇
  1976年   3165篇
  1975年   2865篇
  1974年   2958篇
  1973年   3023篇
  1972年   2353篇
  1971年   1871篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A scheme of magnetic calorimeter for registration of rare events characterized by small energy release (cosmic rays, WIMPs, solitary X-ray quanta) is proposed. The calorimeter is brought to operation by adiabatic demagnetization, and its magnetic response is measured by a quantum interferometer (SQUID, A. Barone and G. Paterno, Physics and applications of Josephson Effect). Special consideration is given to the specific features of calorimeter operation in the ferromagnetic transition region. The trigger registration of ultrasmall energy release by a ferromagnetic system in the metastable state is described.  相似文献   
992.
The supersymetric path integrals in solving the problem of relativistic spinning particle interacting with pseudoscalar potentials is examined. The relative propagator is presented by means of path integral, where the spin degrees of freedom are described by odd Grassmannian variables and the gauge invariant part of the effective action has a form similar to the standard pseudoclassical action given by Berezin and Marinov. After integrating over fermionic variables (Grassmannian variables), the problem is reduced to a nonrelativistic one with an effective supersymetric potential. Some explicit examples are considered, where we have extracted the energy spectrum of the electron and the wave functions. PACS numbers: 03.65. Ca-Formalism, 03.65. Db-Functional analytical methods, 03.65. Pm-Relativistic wave equations.  相似文献   
993.
994.
A study has been made of the acidic ionization, structural conversions, and prototropic tautomerism of rhodamine chromogens in methanol and dimethyl sulfoxide, using IR, 13 C NMR, and electronic spectroscopy. The lactone structure has been established for the colorless form of rhodamines in DMSO. For rhodamine B in mixtures of water with DMSO, the lactone/zwitterion ratio has been estimated.V. I. Vernadskii Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Moscow 117975. Khar'kov State University, Khar'kov 310077. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 512–521, March, 1992.  相似文献   
995.
996.
Exponential growth is estimated for integral operators with continuous periodic kernels of exponential type. The result is applied to the boundary-value problem for a general hyperbolic differential equation having periodic coefficients with Goursat boundary conditions. It is proved that the exponential characteristic for such a boundary-value problem has canonical form. __________ Translated from Sovremennaya Matematika i Ee Prilozheniya (Contemporary Mathematics and Its Applications), Vol. 38, Suzdal Conference-2004, Part 3, 2006.  相似文献   
997.
We discuss derivation‐like techniques for transforming one locally Hermitian partial ovoid of the Hermitian surface H(3,q2) into another one. These techniques correspond to replacing a regulus by its opposite in some naturally associated projective 3‐space PG(3,q) over a square root subfield. © 2006 Wiley Periodicals, Inc. J Combin Designs 15: 478–486, 2007  相似文献   
998.
The invariance of the geometric mean G with respect to the Lagrangian mean-type mapping (Lf,Lg), i.e. the equation G○(Lf,Lg)=G, is considered. We show that the functions f and g must be of high class regularity. This fact allows to reduce the problem to a differential equation and determine the second derivatives of the generators f and g.  相似文献   
999.
In the paper we indicate an error made in the proof of the main result of the paper [M.A. Darwish, On quadratic integral equation of fractional orders, J. Math. Anal. Appl. 311 (2005) 112-119]. Moreover, we provide correct proof of a slightly modified version of the mentioned result. The main tool used in our proof is the technique associated with the Hausdorff measure of noncompactness.  相似文献   
1000.
The author proves the existence and uniqueness of a generalized solution of a nonlocal problem with an integral condition for a hyperbolic equation with n spatial variables. This work is a continuation of the studies started in [3–5], where the solvability problem of nonlocal problems with an integral condition was studied for hyperbolic equations on the plane. __________ Translated from Sovremennaya Matematika i Ee Prilozheniya (Contemporary Mathematics and Its Applications), Vol. 33, Suzdal Conference-2004, Part 1, 2005.  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