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   85508篇
  免费   685篇
  国内免费   411篇
化学   29564篇
晶体学   805篇
力学   6895篇
数学   33205篇
物理学   16135篇
  2023年   77篇
  2022年   112篇
  2021年   135篇
  2020年   189篇
  2019年   191篇
  2018年   10500篇
  2017年   10335篇
  2016年   6380篇
  2015年   1144篇
  2014年   573篇
  2013年   768篇
  2012年   4292篇
  2011年   11065篇
  2010年   5973篇
  2009年   6328篇
  2008年   7035篇
  2007年   9159篇
  2006年   642篇
  2005年   1693篇
  2004年   1863篇
  2003年   2267篇
  2002年   1284篇
  2001年   413篇
  2000年   404篇
  1999年   271篇
  1998年   281篇
  1997年   247篇
  1996年   300篇
  1995年   203篇
  1994年   137篇
  1993年   159篇
  1992年   108篇
  1991年   99篇
  1990年   85篇
  1989年   87篇
  1988年   94篇
  1987年   84篇
  1986年   90篇
  1985年   70篇
  1984年   64篇
  1983年   50篇
  1982年   63篇
  1981年   54篇
  1980年   66篇
  1979年   55篇
  1978年   55篇
  1914年   45篇
  1912年   41篇
  1909年   42篇
  1908年   41篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The modified Gross–Pitaevskii equation was derived and solved to obtain the 1D solution in the zero-energy limit. This stationary solution could account for the dominated contributions due to the kinetic effect as well as the chemical potential in inhomogeneous Bose gases.  相似文献   
102.
103.
The characteristic exponent α of a Lévy-stable law S α (σ, β, μ) was thoroughly studied as the extreme value index of a heavy tailed distribution. For 1 < α < 2, Peng (Statist. Probab. Lett. 52: 255–264, 2001) has proposed, via the extreme value approach, an asymptotically normal estimator for the location parameter μ. In this paper, we derive by the same approach, an estimator for the scale parameter σ and we discuss its limiting behavior.   相似文献   
104.
105.
106.
107.
With a given holomorphic section of a Hermitian vector bundle, one can associate a residue current by means of Cauchy–Fantappiè–Leray type formulas. In this paper we define products of such residue currents. We prove that, in the case of a complete intersection, the product of the residue currents of a tuple of sections coincides with the residue current of the direct sum of the sections.  相似文献   
108.
In this paper,we will establish several strong convergence theorems for the approximation ofcommon fixed points of r-strictly asymptotically pseudocontractive mappings in uniformly convex Banachspaces using the modiied implicit iteration sequence with errors,and prove the necessary and sufficient conditionsfor the convergence of the sequence.Our results generalize,extend and improve the recent work,in thistopic.  相似文献   
109.
We prove a Penrose-like inequality for the mass of a large class of constant mean curvature (CMC) asymptotically flat n-dimensional spin manifolds which satisfy the dominant energy condition and have a future converging, or past converging compact and connected boundary of non-positive mean curvature and of positive Yamabe invariant. We prove that for every n ≥ 3 the mass is bounded from below by an expression involving the norm of the linear momentum, the volume of the boundary, dimensionless geometric constants and some normalized Sobolev ratio.  相似文献   
110.
In cricket, a rain-affected pitch can make batting more difficult than normal. Several other conditions such as poor light or an initially lively pitch, may also result in difficulties for the batsmen. In this note, we refer to all of them as ‘sticky wickets’. On sticky wickets, lower order batsmen are often sent into ‘hold the fort’ until conditions improve. In this paper, a stochastic dynamic programming model is used to examine the appropriateness of this policy. The model suggests that the tactic is often optimal when the sticky wicket persists until the end of the day's play, but not often when the sticky wicket is transitory. In some circumstances, it is worthwhile, on a normal wicket near the end of the day, to send in a lower order batsman to hold the fort (a night watchman): when the wicket is sticky, this tactic is even more worthwhile.  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