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   404899篇
  免费   4421篇
  国内免费   1276篇
化学   217664篇
晶体学   5687篇
力学   18391篇
综合类   16篇
数学   45621篇
物理学   123217篇
  2020年   3004篇
  2019年   3290篇
  2018年   4097篇
  2017年   4103篇
  2016年   6439篇
  2015年   4289篇
  2014年   6361篇
  2013年   17165篇
  2012年   13210篇
  2011年   16329篇
  2010年   11108篇
  2009年   11018篇
  2008年   15187篇
  2007年   15439篇
  2006年   14564篇
  2005年   13350篇
  2004年   12149篇
  2003年   10875篇
  2002年   10739篇
  2001年   12060篇
  2000年   9328篇
  1999年   7132篇
  1998年   5961篇
  1997年   5926篇
  1996年   5659篇
  1995年   5176篇
  1994年   5242篇
  1993年   4826篇
  1992年   5536篇
  1991年   5545篇
  1990年   5225篇
  1989年   5105篇
  1988年   5188篇
  1987年   5053篇
  1986年   4769篇
  1985年   6577篇
  1984年   6837篇
  1983年   5663篇
  1982年   5909篇
  1981年   5656篇
  1980年   5571篇
  1979年   5559篇
  1978年   5916篇
  1977年   5847篇
  1976年   5871篇
  1975年   5523篇
  1974年   5477篇
  1973年   5698篇
  1972年   3839篇
  1971年   3018篇
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
101.
Radiophysics and Quantum Electronics - Wind-related weather hazards remain difficult to recognize targets for weather radars. Methods that use estimates of the width of the reflected-signal...  相似文献   
102.
Russian Journal of General Chemistry - Highly dispersed CaO has been synthesized by heating an aqueous solution of calcium nitrate and D-glucose up to 800°C. Calcium oxide is formed with an...  相似文献   
103.

A model with 16 moments is here presented in the framework of RET of polyatomic gases. It furnishes as principal subsystem the relativistic counterpart of a work by Arima T., Ruggeri T., Sugiyama M.; this is present in literature and treats the non relativistic case which incorporates relaxation processes of molecular rotation and vibration. Another principal subsystem is the natural extension of the 14 moments model by Pennisi S. and Ruggeri T.; this is also present in literature in the relativistic framework but where the trace of the third balance equation is neglected. Its extension is found here for the case when this trace isn’t neglected.

  相似文献   
104.
Exosomes are nanovesicles secreted by most cellular types that carry important biochemical compounds throughout the body with different purposes, playing a preponderant role in cellular communication. Because of their structure, physicochemical properties and stability, recent studies are focusing in their use as nanocarriers for different therapeutic compounds for the treatment of different diseases ranging from cancer to Parkinson's disease. However, current bioseparation protocols and methodologies are selected based on the final exosome application or intended use and present both advantages and disadvantages when compared among them. In this context, this review aims to present the most important technologies available for exosome isolation while discussing their advantages and disadvantages and the possibilities of being combined with other strategies. This is critical since the development of novel exosome‐based therapeutic strategies will be constrained to the effectiveness and yield of the selected downstream purification methodologies for which a thorough understanding of the available technological resources is needed.  相似文献   
105.
Journal of Analytical Chemistry - HPTLC is a widely used tool in standardization of herbs because of its ability to estimate the presence of active components in samples. HPTLC-bioautography is a...  相似文献   
106.
Journal of Applied Spectroscopy - Aqueous solutions of human hemoglobin have been studied by the multi-angle static light scattering method. The tendency of sickle-shaped erythrocytes to aggregate...  相似文献   
107.
Xu  H. J.  Zhang  Q. G.  Debenest  G. 《Transport in Porous Media》2021,140(3):625-627
Transport in Porous Media - The theme of coupling problems for adsorption, absorption and thermochemical transport in porous media is very important for engineering applications. Based on the...  相似文献   
108.
Aliev  A. B.  Shafieva  G. H. 《Differential Equations》2022,58(8):1028-1042
Differential Equations - We study a mixed problem for systems of one-dimensional semilinear hyperbolic equations with variable nonlinearity growth rate and nonlinear boundary conditions. Theorems...  相似文献   
109.
Journal of Sol-Gel Science and Technology - High temperature stable brookite rich titanium dioxide of average crystallite size 20&;nbsp;nm has been prepared by a novel aqueous sol–gel...  相似文献   
110.
Saleh  Z. M.  Nasser  H.  Özkol  E.  Günöven  M.  Abak  K.  Canli  S.  Bek  A.  Turan  R. 《Journal of nanoparticle research》2015,17(10):1-12
Journal of Nanoparticle Research - Plasmonic interfaces consisting of silver nanoparticles of different sizes (50–100&;nbsp;nm) have been processed by the self-assembled dewetting...  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