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   224721篇
  免费   2618篇
  国内免费   1460篇
化学   125088篇
晶体学   3377篇
力学   8626篇
综合类   72篇
数学   24980篇
物理学   66656篇
  2021年   2028篇
  2020年   2291篇
  2019年   2555篇
  2018年   3450篇
  2017年   3362篇
  2016年   4726篇
  2015年   2797篇
  2014年   4302篇
  2013年   9949篇
  2012年   7753篇
  2011年   9371篇
  2010年   6755篇
  2009年   6512篇
  2008年   8869篇
  2007年   8920篇
  2006年   8264篇
  2005年   7466篇
  2004年   6631篇
  2003年   5931篇
  2002年   5743篇
  2001年   6070篇
  2000年   4784篇
  1999年   3580篇
  1998年   3068篇
  1997年   3098篇
  1996年   2888篇
  1995年   2366篇
  1994年   2461篇
  1993年   2492篇
  1992年   2630篇
  1991年   2685篇
  1990年   2592篇
  1989年   2554篇
  1988年   2480篇
  1987年   2458篇
  1986年   2371篇
  1985年   3064篇
  1984年   3212篇
  1983年   2571篇
  1982年   2835篇
  1981年   2710篇
  1980年   2515篇
  1979年   2728篇
  1978年   2841篇
  1977年   2861篇
  1976年   2835篇
  1975年   2693篇
  1974年   2671篇
  1973年   2813篇
  1972年   1876篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Kinetics and Catalysis - Boron and barium were employed as dopants for the VMgO system. The catalysts were characterized by ICP-OES, BET, IR, powder XRD, EDX, TPR-H2, TPD-NH3, XPS, and 51V MAS NMR....  相似文献   
93.
Krabbe disease is a devastating neurodegenerative disorder characterized by rapid demyelination of nerve fibers. This disease is caused by defects in the lysosomal enzyme β-galactocerebrosidase (GALC), which hydrolyzes the terminal galactose from glycosphingolipids. These lipids are essential components of eukaryotic cell membranes: substrates of GALC include galactocerebroside, the primary lipid component of myelin, and psychosine, a cytotoxic metabolite. Mutations of GALC that cause misfolding of the protein may be responsive to pharmacological chaperone therapy (PCT), whereby small molecules are used to stabilize these mutant proteins, thus correcting trafficking defects and increasing residual catabolic activity in cells. Here we describe a new approach for the synthesis of galacto-configured azasugars and the characterization of their interaction with GALC using biophysical, biochemical and crystallographic methods. We identify that the global stabilization of GALC conferred by azasugar derivatives, measured by fluorescence-based thermal shift assays, is directly related to their binding affinity, measured by enzyme inhibition. X-ray crystal structures of these molecules bound in the GALC active site reveal which residues participate in stabilizing interactions, show how potency is achieved and illustrate the penalties of aza/iminosugar ring distortion. The structure–activity relationships described here identify the key physical properties required of pharmacological chaperones for Krabbe disease and highlight the potential of azasugars as stabilizing agents for future enzyme replacement therapies. This work lays the foundation for new drug-based treatments of Krabbe disease.  相似文献   
94.
Colloid Journal - It has been found that the addition of ammonia water to a gold sol obtained by the Duff method induces the growth of the gold particles. The growth kinetics of such particles in...  相似文献   
95.
96.
97.
98.
Kim  F. H.  Moylan  S. P.  Phan  T. Q.  Garboczi  E. J. 《Experimental Mechanics》2020,60(7):987-1004
Experimental Mechanics - Insufficient data are available to fully understand the effects of metal additive manufacturing (AM) defects for widespread adoption of the emerging technology....  相似文献   
99.
Journal of Analytical Chemistry - A new liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method has been developed and validated for alfuzosin quantification in...  相似文献   
100.
π-Extended molecules are key components for the development of materials science. In fact, polyaromatic structures are fundamental for the scientific and technological progress of fields such as organic electronics and bio-applications. Beneficial properties of π-extended structures are absorption in the visible region, often luminescence, high electron mobilities and stability. Common approaches to adjust the properties of polyaromatic structures to functional setups involve changes in shape and size at the molecular level. Recently, incorporating hetero-elements emerged as successful approach. In this regard, organophosphorus conjugated molecules are new materials holding great promise for potential applications. In this review, we comprehensively discuss the design/development of polyaromatic phosphorus materials and their applicability. We establish structure/property/applicability relationships to provide key guidelines for the engineering of newer, future applications. This article thus provides a source of information for the further development of this rapidly evolving field of research.  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