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   242篇
  免费   4篇
  国内免费   1篇
化学   120篇
力学   2篇
数学   48篇
物理学   77篇
  2021年   2篇
  2019年   5篇
  2017年   6篇
  2016年   10篇
  2015年   4篇
  2014年   3篇
  2013年   10篇
  2012年   9篇
  2011年   21篇
  2010年   11篇
  2009年   4篇
  2008年   10篇
  2007年   11篇
  2006年   8篇
  2005年   12篇
  2004年   10篇
  2003年   4篇
  2002年   8篇
  2001年   2篇
  2000年   3篇
  1996年   6篇
  1994年   2篇
  1993年   1篇
  1992年   6篇
  1991年   3篇
  1990年   1篇
  1989年   1篇
  1988年   3篇
  1987年   4篇
  1986年   2篇
  1985年   6篇
  1983年   3篇
  1982年   2篇
  1981年   4篇
  1980年   4篇
  1979年   4篇
  1978年   4篇
  1977年   3篇
  1976年   3篇
  1975年   7篇
  1974年   6篇
  1973年   5篇
  1972年   1篇
  1969年   2篇
  1967年   1篇
  1966年   1篇
  1964年   1篇
  1963年   1篇
  1935年   2篇
  1929年   1篇
排序方式: 共有247条查询结果,搜索用时 0 毫秒
11.
Given a large weighted Hardy space we show there exists a composition operatorC with that maps from that space into the unweighted Dirichlet space and lies in every Schatten p-class for 0<p<. This is in contrast to the situation in which the image space is a smaller weighted Dirichlet space. It is known that in that case it is not possible to find such a composition operator that is bounded.This research was supported in part by a summer stipend from Bellarmine College.  相似文献   
12.
The strong consistency of least squares estimates in multiple regression models is established under minimal assumptions on the design and weak dependence and moment restrictions on the errors.  相似文献   
13.
14.
The competing effects of slow structural relaxations (aging) and deformation at constant strain rate on the shear yield stress tau(y) of simple model glasses are examined using molecular simulations. At long times, aging leads to a logarithmic increase in density and tau(y). The yield stress also rises logarithmically with rate but shows a sharp transition in slope at a rate that decreases with increasing age. We present a simple phenomenological model that includes both intrinsic rate dependence and the change in properties with the total age of the system at yield. As predicted by the model, all data for each temperature collapse onto a universal curve.  相似文献   
15.
16.
17.
18.
Propargyl imidates derived from aromatic and aliphatic nitriles cyclize at room temperature in high yields when treated with a catalytic amount of copper (I) iodide. This 5-exo-dig process affords dihydrooxazoles which do not aromatize under the reaction conditions, and which are isolated without chromatography. Investigations of the reaction scope, subsequent functionalization of the reaction products, and preliminary mechanistic data are presented.  相似文献   
19.
Cesium containing glass with solid metal electrodes was used as a Cs atom source in a high vacuum system. A silver anode provides an injection source of highly mobile ions which sweep Cs to the cathode surface, from which they evaporate into the vacuum. Cathode metallization with finger patterns was used leaving bare glass for Cs evaporation. Laser absorption measurements show Cs vapor generation synchronous with an applied DC voltage.  相似文献   
20.
Photochemical approaches afford high spatiotemporal control over molecular structure and function, for broad applications in materials and biological science. Here, we present the first example of a visible light responsive ruthenium-based photolinker, Ru(bipyridine)2(3-ethynylpyridine)2 (RuBEP), which was reacted stoichiometrically with a 25mer DNA or morpholino (MO) oligonucleotide functionalized with 3′ and 5′ terminal azides, via Cu(i)-mediated [3+2] Huisgen cycloaddition reactions. RuBEP-caged circular morpholinos (Ru-MOs) targeting two early developmental zebrafish genes, chordin and notail, were synthesized and tested in vivo. One-cell-stage zebrafish embryos microinjected with Ru-MO and incubated in the dark for 24 h developed normally, consistent with caging, whereas irradiation at 450 nm dissociated one 3-ethynylpyridine ligand (Φ = 0.33) and uncaged the MO to achieve gene knockdown. As demonstrated, Ru photolinkers provide a versatile method for controlling structure and function of biopolymers.  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