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   2509篇
  免费   72篇
  国内免费   22篇
化学   1728篇
晶体学   5篇
力学   31篇
数学   426篇
物理学   413篇
  2023年   14篇
  2022年   15篇
  2021年   26篇
  2020年   30篇
  2019年   34篇
  2018年   29篇
  2017年   25篇
  2016年   44篇
  2015年   45篇
  2014年   51篇
  2013年   113篇
  2012年   152篇
  2011年   207篇
  2010年   85篇
  2009年   65篇
  2008年   163篇
  2007年   145篇
  2006年   154篇
  2005年   145篇
  2004年   150篇
  2003年   121篇
  2002年   109篇
  2001年   33篇
  2000年   39篇
  1999年   32篇
  1998年   26篇
  1997年   26篇
  1996年   31篇
  1995年   34篇
  1994年   24篇
  1993年   28篇
  1992年   22篇
  1991年   20篇
  1990年   23篇
  1988年   23篇
  1987年   12篇
  1986年   11篇
  1985年   28篇
  1984年   30篇
  1983年   17篇
  1982年   23篇
  1981年   22篇
  1980年   24篇
  1979年   16篇
  1978年   14篇
  1977年   11篇
  1976年   10篇
  1975年   13篇
  1974年   11篇
  1973年   20篇
排序方式: 共有2603条查询结果,搜索用时 15 毫秒
1.
Journal of Fluorescence - This report describes a combined immunofluorescence and fluorescence viability stain applied as one staining solution for rapid detection of live Legionella...  相似文献   
2.
3.
4.
A novel dinitroxide mediating agent that was suitable for stable free‐radical polymerization was synthesized and used in the block copolymerization of styrene and t‐butyl styrene. Quantitative yields of a novel dinitroxide based on 1,6‐hexamethylene diisocyanate and 4‐hydroxy‐2,2,6,6‐tetramethyl‐1‐piperidinyloxy were obtained. Various experimental parameters, including the nitroxide‐to‐initiator molar ratio, were examined, and it was determined that the polymerization was most controlled under conditions similar to those of conventional 2,2,6,6‐tetramethyl‐1‐piperidinyloxy‐mediated stable free‐radical polymerization. Moreover, the dinitroxide mediator proved to be a viable route for the facile two‐step synthesis of triblock copolymers of styrene and t‐butyl styrene. However, the dinitroxide mediation process resulted in a higher than expected level of nitroxide decomposition, which resulted in polymers possessing a terminal alkoxyamine and an adjacent hydroxylamine rather than a preferred internal bisalkoxyamine. This decomposition resulted in the formation of diblock copolymer species during the triblock copolymer synthesis. Gel permeation chromatography was used to monitor the chain‐end decomposition kinetics, and the determined observed rate constant (5.89 × 10?5 s?1) for decomposition agreed well with previous studies for other dinitroxide mediating agents. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1547–1556, 2004  相似文献   
5.
6.
7.
The synthesis and characterization of a collagen mimetic dendrimer composed of the Gly-Pro-Nleu sequence is described. The dendrimer is built on a ‘first generation’ poly(amidoamine) core and is synthesized in 38% yield. This dendrimer exhibits a melting temperature of 25 °C, which is in between previously studied analogous molecules of identical sequence and length.  相似文献   
8.
Radical reaction of a series of N-(2-bromoallyl)arylcarboxamides led to the production of 4-arylpyrrolidin-2-ones and directly reduced materials in comparable yields. A cascade process, involving sequential 5-exo-trig spirocyclisation, β-scission, and 5-endo-trig cyclisation of the resulting acyl radical, is proposed to explain the pyrrolidinone products.  相似文献   
9.
10.
Four human cone pigment apoproteins were expressed by transfection of human tissue culture cells with the corresponding complementary DNA clones. Following reconstitution of the cone pigments by incubation with 11-cis retinal, photobleaching difference absorption spectra were obtained for the blue pigment, the green pigment, and two polymorphic variants of the red pigment. These spectra were analyzed to determine the wavelengths of maximal absorbance and the bandwidths. The recombinant cone pigment spectra were compared to human cone spectral sensitivities and cone pigment absorption spectra determined by microspectrophotometry, single-cell electrophysiology, reflection densitometry, electroretinography, and psychophysical color and brightness matching.  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