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   29277篇
  免费   894篇
  国内免费   233篇
化学   20053篇
晶体学   142篇
力学   663篇
综合类   1篇
数学   5505篇
物理学   4040篇
  2022年   185篇
  2021年   319篇
  2020年   404篇
  2019年   363篇
  2018年   297篇
  2017年   319篇
  2016年   649篇
  2015年   679篇
  2014年   702篇
  2013年   1461篇
  2012年   1470篇
  2011年   1779篇
  2010年   989篇
  2009年   850篇
  2008年   1506篇
  2007年   1504篇
  2006年   1593篇
  2005年   1417篇
  2004年   1342篇
  2003年   1116篇
  2002年   1064篇
  2001年   466篇
  2000年   417篇
  1999年   406篇
  1998年   397篇
  1997年   435篇
  1996年   403篇
  1995年   367篇
  1994年   395篇
  1993年   353篇
  1992年   325篇
  1991年   328篇
  1990年   286篇
  1989年   291篇
  1988年   268篇
  1987年   224篇
  1986年   250篇
  1985年   370篇
  1984年   374篇
  1983年   320篇
  1982年   358篇
  1981年   324篇
  1980年   346篇
  1979年   273篇
  1978年   302篇
  1977年   293篇
  1976年   230篇
  1975年   200篇
  1974年   201篇
  1973年   173篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
We propose means for computing the Fourier expansions of periodic functions appearing in higher moments of the sum-of-digits function and in the solutions of some divide-and-conquer recurrences. The expansions are shown to be absolutely convergent. We also give a new approach to efficiently compute numerically the coefficients involved to high precision.  相似文献   
62.
The questions raised by A. M. Turing in his paper on thought and machines are discussed. Human thought is considered in turn as a concept of normal language usage, as a basic concept of psychology, and as the basis of intellectual activity. It is concluded that neither of these notions of thought identifies something specific that a human being can or cannot do. The imitation game proposed by Turing for deciding whether a machine can think is found to result from an arbitrary empoverishment of the channel of communication between the interrogator and the item under investigation. Turing's notions of thinking are shown to lead to logical difficulties. An alternative view of consciousness, that would place it beyond the reach of any finite test, is finally discussed.  相似文献   
63.
This paper shows that the dimension of internal structure of a component can be measured remotely to a resolution better than 5 μm by use of the combination of high resolution optical microscopy and image processing.A specialised high resolution, long working distance and diffraction limited lens was used to image within the component. A series of digital images were made to map spatially the interior of the component. An edge detector was then used to localise the specific location of features in order that an accurate internal measurement could be made. A visualisation of the internal surface finish was also achieved.  相似文献   
64.
65.
66.
67.
Periodica Mathematica Hungarica - Let ?= 2ν &;gt; 1. Let M be an orientable manifold of odd dimension m with $\pi _1 (M) = \mathbb{Z}_\ell $ whose universal cover $\tilde M$ is...  相似文献   
68.
In the present article, we aim at treating the existence of fundamental solutions of linear partial differential operators with constant coefficients from the viewpoint of setting up explicit formulae yielding fundamental solutions.  相似文献   
69.
A new scheme for controlling photodissociation through preparation of a variationally optimized linear superposition of field free vibrational eigenstates is applied for selective control of IBr and HI dissociation. The dependence of photodissociation on various field parameters and initial conditions is examined to investigate the mechanistic basis of selective control. The parametric equations of motion approach for determining vibrational dynamics as a function of field parameters without having to solve the time dependent Schrödinger equation explicitly for each field parameter separately is outlined and its use to identify field characteristics which will provide the requisite population mix represented by the optimal linear superposition of vibrational states is advocated.  相似文献   
70.
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