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   77954篇
  免费   382篇
  国内免费   426篇
化学   24141篇
晶体学   795篇
力学   6733篇
综合类   2篇
数学   31991篇
物理学   15100篇
  2021年   29篇
  2018年   10437篇
  2017年   10273篇
  2016年   6065篇
  2015年   850篇
  2014年   293篇
  2013年   324篇
  2012年   3790篇
  2011年   10491篇
  2010年   5621篇
  2009年   6044篇
  2008年   6581篇
  2007年   8748篇
  2006年   214篇
  2005年   1286篇
  2004年   1523篇
  2003年   1966篇
  2002年   1005篇
  2001年   242篇
  2000年   291篇
  1999年   152篇
  1998年   190篇
  1997年   147篇
  1996年   202篇
  1995年   119篇
  1994年   79篇
  1993年   97篇
  1992年   54篇
  1991年   70篇
  1990年   53篇
  1989年   59篇
  1988年   59篇
  1987年   58篇
  1986年   57篇
  1985年   47篇
  1984年   45篇
  1983年   38篇
  1982年   41篇
  1981年   38篇
  1980年   46篇
  1979年   45篇
  1978年   34篇
  1973年   25篇
  1914年   45篇
  1913年   40篇
  1912年   40篇
  1909年   41篇
  1908年   40篇
  1907年   32篇
  1904年   28篇
排序方式: 共有10000条查询结果,搜索用时 781 毫秒
1.
Zhang  Junyu  Hong  Mingyi  Zhang  Shuzhong 《Mathematical Programming》2022,194(1-2):901-935
Mathematical Programming - In this paper, we study the lower iteration complexity bounds for finding the saddle point of a strongly convex and strongly concave saddle point problem: $$\min _x\max...  相似文献   
2.
In the paper, the authors establish several integral representations for the generating functions of the large and little Schröder numbers and for the large and little Schröder numbers.  相似文献   
3.
Mesoscopic modeling at the pore scale offers great promise in exploring the underlying structure transport performance of flow through porous media. The present work studies the fluid flow subjected to capillarity-induced resonance in porous media characterized by different porous structure and wettability. The effects of porosity and wettability on the displacement behavior of the fluid flow through porous media are discussed. The results are presented in the form of temporal evolution of percentage saturation and displacement of the fluid front through porous media. The present study reveals that the vibration in the form of acoustic excitation could be significant in the mobilization of fluid through the porous media. The dependence of displacement of the fluid on physicochemical parameters like wettability of the surface, frequency along with the porosity is analyzed. It was observed that the mean displacement of the fluid is more in the case of invading fluid with wetting phase where the driving force strength is not so dominant.  相似文献   
4.
5.
We prove that the group of diffeomorphisms of the interval [0, 1] contains surface groups whose action on (0, 1) has no global fix point and such that only countably many points of the interval (0, 1) have non-trivial stabiliser.  相似文献   
6.
7.
8.
9.
Mass spectrometry (MS) driven metabolomics is a frequently used tool in various areas of life sciences; however, the analysis of polar metabolites is less commonly included. In general, metabolomic analyses lead to the detection of the total amount of all covered metabolites. This is currently a major limitation with respect to metabolites showing high turnover rates, but no changes in their concentration. Such metabolites and pathways could be crucial metabolic nodes (e.g., potential drug targets in cancer metabolism). A stable-isotope tracing capillary electrophoresis–mass spectrometry (CE-MS) metabolomic approach was developed to cover both polar metabolites and isotopologues in a non-targeted way. An in-house developed software enables high throughput processing of complex multidimensional data. The practicability is demonstrated analyzing [U-13C]-glucose exposed prostate cancer and non-cancer cells. This CE-MS-driven analytical strategy complements polar metabolite profiles through isotopologue labeling patterns, thereby improving not only the metabolomic coverage, but also the understanding of metabolism.  相似文献   
10.
The structure and properties of 12Cr1MoV steel irradiated with a zirconium ion beam were studied by optical microscopy, scanning electron microscopy, and micro- and nanoindentation. It is shown that the modification covers the entire cross-section of the irradiated specimens to a depth of 1 mm. The data on irradiation-induced structural changes are used to interpret the changes in mechanical properties of the irradiated specimens under static and cyclic loading. Particular attention is given to analysis of strain estimation by the digital image correlation method.  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