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   13202篇
  免费   373篇
  国内免费   4篇
化学   6683篇
晶体学   154篇
力学   275篇
数学   2629篇
物理学   3838篇
  2021年   161篇
  2020年   165篇
  2019年   164篇
  2018年   200篇
  2017年   208篇
  2016年   462篇
  2015年   426篇
  2014年   472篇
  2013年   917篇
  2012年   600篇
  2011年   672篇
  2010年   476篇
  2009年   410篇
  2008年   380篇
  2007年   349篇
  2006年   304篇
  2005年   173篇
  2004年   208篇
  2003年   209篇
  2002年   220篇
  2001年   182篇
  2000年   220篇
  1999年   183篇
  1998年   171篇
  1997年   164篇
  1996年   168篇
  1995年   159篇
  1994年   154篇
  1993年   164篇
  1992年   153篇
  1991年   138篇
  1990年   151篇
  1989年   133篇
  1988年   144篇
  1987年   145篇
  1986年   120篇
  1985年   179篇
  1984年   187篇
  1983年   134篇
  1982年   156篇
  1981年   149篇
  1980年   151篇
  1979年   161篇
  1978年   152篇
  1977年   144篇
  1976年   162篇
  1975年   166篇
  1974年   155篇
  1973年   115篇
  1965年   115篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
901.
Making use of a surface integral defined without use of the partition of unity, trace theorems and the Gauss-Ostrogradskij theorem are proved in the case of three-dimensional domains with a Lipschitz-continuous boundary for functions belonging to the Sobolev spaces H 1,p () (1 p < ). The paper is a generalization of the previous author's paper which is devoted to the line integral.  相似文献   
902.
Variational inequalities are studied, where K is a closed convex cone in , 3, B is a × matrix, G is a small perturbation, a real parameter. The assumptions guaranteeing a Hopf bifurcation at some 0 for the corresponding equation are considered and it is proved that then, in some situations, also a bifurcation of periodic solutions to our inequality occurs at some I 0. Bifurcating solutions are obtained by the limiting process along branches of solutions to penalty problems starting at 0 constructed on the basis of the Alexander-Yorke theorem as global bifurcation branches of a certain enlarged system.  相似文献   
903.
We study limit distribution of partial sums SN,k(t) = s = 1 [N t] Ak(Xs) of Appell polynomials of the long-range dependent moving average process Xt> = i t bt - i i, where {i} is a strictly stationary and weakly dependent martingale difference sequence, and bi id - 1 (0 < d < 1/2). We show that if k(1-2 d)<1, then suitably normalized partial sums SN,k(t) converge in distribution to the kth order Hermite process. This result generalizes the corresponding results of Surgailis, and Avram and Taqqu obtained in the case of the i.i.d. sequence { i}.  相似文献   
904.
For a projection estimator fn of an unknown density f we investigate the behavior of large deviations probability P{Tn > rn} when rn , where Tn is appropriately centered and normed quadratic error fn-f)2.  相似文献   
905.
We present in this work some new theoretical results concerning an influence of the shape of core on the development of magnetization. As a special case the rotary symmetric objects with non-homogeneous magnetization were investigated. The shape of core was optimized on the basis of various practical criteria.  相似文献   
906.
Conclusions The developed version of the augmented plane wave method yields eigenvalues and eigenfunctions with higher accuracy than the standard LAPW, preserving its computational efficiency.The approximation of the exact radial solution by the Taylor expansion involving also the second energy derivative of the radial function, except for the first derivative, has two advantages. First, the energy dependence of the logarithmic derivatives atr=R is better described and, therefore, the method is less sensitive to the choice of the centre of expansionE 0 or, equivalently, acceptably accurate eigenvalues are obtained for the broader energy region aroundE 0. The other and probably more important advantage is that the approximate radial solutions are remarkably closer to the exact radial functions inside the muffin-tin sphere. This can be of use when evaluating the measurable quantities depending on the wave functions.  相似文献   
907.
908.
The influence of molecular weight and the mode of binding of HALS stabilisers on their efficiency in the inhibited photo-oxidation of polystyrene and styrene/HALS copolymers was investigated. Photo-oxidation was performed with radiation of λ > 310 nm and 366 nm. The following functionalised HALS stabilisers were prepared: 4-methacryloylamino-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-1,2,2,6,6-pentamethylpiperidine and 15-methacryloyl-7,15-diazadispiro [5.1,5.3] hexadecane-14,16-dione. Binding by copolymerisation is substantially less efficient than addition of low molecular weight stabiliser.  相似文献   
909.
910.
We prove that the crossing number of graphs with connectivity 2 has in certain cases an additive property analogous to that of crossing number of graphs with connectivity ≤1.  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