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   9548篇
  免费   690篇
  国内免费   10篇
  2023年   64篇
  2022年   99篇
  2021年   331篇
  2020年   162篇
  2019年   198篇
  2018年   255篇
  2017年   203篇
  2016年   271篇
  2015年   451篇
  2014年   500篇
  2013年   689篇
  2012年   719篇
  2011年   673篇
  2010年   416篇
  2009年   383篇
  2008年   490篇
  2007年   494篇
  2006年   428篇
  2005年   396篇
  2004年   405篇
  2003年   326篇
  2002年   343篇
  2001年   177篇
  2000年   139篇
  1999年   114篇
  1998年   79篇
  1997年   66篇
  1996年   55篇
  1995年   51篇
  1994年   37篇
  1993年   37篇
  1992年   68篇
  1991年   84篇
  1990年   82篇
  1989年   67篇
  1988年   77篇
  1987年   53篇
  1986年   46篇
  1985年   64篇
  1984年   54篇
  1983年   54篇
  1982年   38篇
  1981年   32篇
  1980年   34篇
  1979年   42篇
  1978年   48篇
  1977年   38篇
  1976年   38篇
  1974年   41篇
  1973年   29篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
Magnetic field influence on unsteady free convection flow of a second grade fluid near an infinite vertical flat plate with ramped wall temperature embedded in a porous medium is studied. It has been observed that magnitude of velocity as well as skin friction in case of ramped temperature is quite less than the isothermal temperature. Some special cases namely: (i) second grade fluid in the absence of magnetic field and porous medium and (ii) Newtonian fluid in the presence of magnetic field and porous medium, performing the same motion are obtained. Finally, the influence of various parameters is graphically shown.  相似文献   
2.
3.
4.
Perspective texture synthesis has great significance in many fields like video editing, scene capturing etc., due to its ability to read and control global feature information. In this paper, we present a novel example-based, specifically energy optimization-based algorithm, to synthesize perspective textures. Energy optimization technique is a pixel-based approach, so it’s time-consuming. We improve it from two aspects with the purpose of achieving faster synthesis and high quality. Firstly, we change this pixel-based technique by replacing the pixel computation with a little patch. Secondly, we present a novel technique to accelerate searching nearest neighborhoods in energy optimization. Using k- means clustering technique to build a search tree to accelerate the search. Hence, we make use of principal component analysis (PCA) technique to reduce dimensions of input vectors. The high quality results prove that our approach is feasible. Besides, our proposed algorithm needs shorter time relative to other similar methods.  相似文献   
5.
Generation of the functionally pleiotropic members of the endothelin vasoactive peptide family is critically catalyzed by unique type II metalloproteases, termed endothelin converting enzymes (ECE). Isolation of human ECE-2 (EC 3.4.24.71) cDNAs revealed deduced open reading frames of 787 and 765 amino acids with approximately 60% identity with human ECE-1. Characterization of mRNA variants revealed mRNA structural diversity at the 5'-terminus. Two mRNA species exist containing distinct first and second exons. Furthermore, in one of these species, an in-frame deletion of the intracytoplasmic domain removed 29 amino acids. Because of the previously reported human genetic diseases ascribed to germline mutations of member genes of the endothelin family, ECE2 was localized in human chromosomes with fluorescence in situ hybridization and radiation hybrid mapping to 3q28-q29 and SHGC-20171/D3S1571, respectively.  相似文献   
6.
A rapid, sensitive, assay for enzymes that degrade heparin is described. The procedure is based on the interference of heparin with color development during the interaction of protein with the dye Coomassie brilliant blue. The loss of this property when the glycosaminoglycan is degraded by heparinase can be used to quantify activity of the enzyme in pure form, or in complex biological samples such as tissue homogenates or serum. The assay is also suitable for studying dependence of heparinase activity under conditions such as varying pH and temperature.  相似文献   
7.
8.
9.
10.
Wetlands Ecology and Management -  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