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   6991篇
  免费   177篇
  国内免费   24篇
化学   4982篇
晶体学   26篇
力学   123篇
数学   1051篇
物理学   1010篇
  2020年   68篇
  2019年   64篇
  2016年   113篇
  2015年   106篇
  2014年   130篇
  2013年   226篇
  2012年   202篇
  2011年   292篇
  2010年   161篇
  2009年   139篇
  2008年   272篇
  2007年   248篇
  2006年   264篇
  2005年   268篇
  2004年   222篇
  2003年   186篇
  2002年   207篇
  2001年   116篇
  2000年   110篇
  1999年   102篇
  1998年   76篇
  1997年   98篇
  1996年   103篇
  1995年   108篇
  1994年   79篇
  1993年   84篇
  1992年   94篇
  1991年   77篇
  1990年   89篇
  1989年   65篇
  1988年   84篇
  1987年   93篇
  1986年   55篇
  1985年   122篇
  1984年   81篇
  1983年   85篇
  1982年   88篇
  1981年   87篇
  1980年   83篇
  1979年   88篇
  1978年   85篇
  1977年   67篇
  1976年   94篇
  1975年   89篇
  1974年   73篇
  1973年   69篇
  1972年   53篇
  1970年   64篇
  1967年   55篇
  1966年   52篇
排序方式: 共有7192条查询结果,搜索用时 359 毫秒
11.
An effective residual interaction between particles and holes for shell model calculations around 208Pb, derived from the interaction between free nucleons, is compared with the measured properties of proton-hole neutron states in 208Tl and the interaction between proton holes is adjusted to newly measured level energies in 206Hg. These interaction elements are particularly relevant for neutron-rich nuclei. The adjustment of two mixing elements reproduces the known γ-decay data in 208Tl. Received: 2 April 2002 / Accepted: 2 May 2002  相似文献   
12.
The controlled squeezing of electromagnetic energy into nanometric volumes via surface plasmon-polariton excitations in plasmonic nanoresonators is analyzed using the concept of an effective electromagnetic mode volume V eff, while taking careful account of the plasmon-polariton dispersion and the electromagnetic energy stored in the metal. Together with the quality factor Q of the cavity resonance, this enables a comparison with dielectric optical cavities, where V eff is limited by diffraction. For a Fabry–Perot type planar metallic cavity, a one-dimensional analytic model as well as a three-dimensional finite-difference time-domain simulation reveal that V eff is not bounded by diffraction, and that Q/V eff increases for decreasing cavity size. In this picture, matter–plasmon interactions can be quantified in terms of Q and V eff, and a resonant cavity model for the enhancement of spontaneous Raman scattering is presented.  相似文献   
13.
As part of an examination of the cytostatic effects of 1,2-diarylethylenediamine-platinum(II)-complexes the contents of platinum and biologically essential trace elements of tumour tissue and different organs were determined. The activation analysis procedure — separation of32P, isolation of199Au and99Mo — is described. In the course of a pharmakokinetical experiment with tumourbearing rats (DMBA induced hormone-dependent tumours) the desired enrichment of the administered drug in the tumour tissue was found. Changes of the trace element level of tumour tissue were found for hormone-dependent MXT-mammary tumours on mice.  相似文献   
14.
15.
16.
The notion of interaction antieigenvalue, which I mentioned over thirty years ago but which to date has not been elaborated, will be briefly elaborated here. New bounds will be obtained from it.  相似文献   
17.
The aim of this paper is to propose an algorithm based on the philosophy of the Variable Neighborhood Search (VNS) to solve Multi Depot Vehicle Routing Problems with Time Windows. The paper has two main contributions. First, from a technical point of view, it presents the first application of a VNS for this problem and several design issues of VNS algorithms are discussed. Second, from a problem oriented point of view the computational results show that the approach is competitive with an existing Tabu Search algorithm with respect to both solution quality and computation times.  相似文献   
18.
This study provides a stability theory for the nonlinear least-squares formulation of estimating the diffusion coefficient in a two-point boundary-value problem from an error-corrupted observation of the state variable. It is based on analysing the projection of the observation on the nonconvex attainable set.This research was started while G. Chavent visited the Technical University of Graz. Support through the Steiermaerkische Landesregierung is gratefully acknowledged.  相似文献   
19.
20.
Summary The Community Bureau of Reference (BCR) has undertaken the production of a wide range of certified reference materials (CRMs) for the improvement of accuracy and measurement harmony in various areas of concern at European Community level. This paper provides an overview of the sectors of the BCR-programme in the field of environment i.e. for water systems (water, sediment, biota), soil analysis (soil, fertiliser, waste), plant analysis (aquatic and terrestrial plants), analysis related to animals (e.g. muscle or liver) or man (e.g. industry and food).  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