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   47654篇
  免费   1635篇
  国内免费   167篇
化学   25932篇
晶体学   253篇
力学   1268篇
综合类   5篇
数学   8136篇
物理学   13862篇
  2023年   298篇
  2021年   412篇
  2020年   611篇
  2019年   486篇
  2018年   678篇
  2017年   645篇
  2016年   1321篇
  2015年   1045篇
  2014年   1180篇
  2013年   2503篇
  2012年   2268篇
  2011年   2446篇
  2010年   1646篇
  2009年   1409篇
  2008年   2210篇
  2007年   2127篇
  2006年   2049篇
  2005年   1801篇
  2004年   1591篇
  2003年   1253篇
  2002年   1136篇
  2001年   981篇
  2000年   828篇
  1999年   587篇
  1998年   524篇
  1997年   493篇
  1996年   611篇
  1995年   527篇
  1994年   569篇
  1993年   573篇
  1992年   626篇
  1991年   451篇
  1990年   455篇
  1989年   427篇
  1988年   382篇
  1987年   396篇
  1986年   364篇
  1985年   555篇
  1984年   534篇
  1983年   443篇
  1982年   474篇
  1981年   482篇
  1980年   457篇
  1979年   455篇
  1978年   435篇
  1977年   430篇
  1976年   415篇
  1975年   395篇
  1974年   383篇
  1973年   333篇
排序方式: 共有10000条查询结果,搜索用时 406 毫秒
1.
Central European Journal of Operations Research - The paper deals with the analysis of the empirical distribution of returns of selected market indices of developed and developing markets in...  相似文献   
2.
Journal of Fluorescence - A simple microwave-assisted synthesis of nitrogen-doped carbon dots with high oxygen content (O-N-CDs) was carried out with citric acid as a carbon source and...  相似文献   
3.
4.
Computational Mathematics and Modeling - Based on the extended simplest equation method, we construct solitons and other solutions for the nonlinear convection-diffusion-reaction equation with...  相似文献   
5.
Set-Valued and Variational Analysis - R. Tyrell Rockafellar and his collaborators introduced, in a series of works, new regression modeling methods based on the notion of superquantile (or...  相似文献   
6.
The European Physical Journal E - The interstitial tumor microenvironment is composed of heterogeneously organized collagen-rich porous networks as well as channel-like structures and interfaces...  相似文献   
7.
Riociguat is novel antihypertensive drug for treatment of pulmonary hypertension. As such, it is still being tested in many clinical and pharmacokinetic trials. Existing methods that determine serum riociguat and desmethylriociguat (DMR) are based solely on liquid chromatography with mass spectrometry. Therefore, we present a novel capillary electrophoresis with mass spectrometry method (CE-MS) for their determination in human serum as alternative method for ongoing trials. Complete resolution of both analytes was achieved by means of pH optimization of ammonium formate background electrolytes that are fully compatible with ESI/MS detection. Simple liquid-liquid extraction was used as sample pretreatment. The calibration dependence of the method was linear (in the range of 10–1000 ng/mL), with adequate accuracy (90.1–114.9%) and precision (13.4%). LOD and LOQ were arbitrarily set at 10 ng/mL for both analytes. Clinical applicability was validated using serum samples from patients treated with riociguat in pharmacokinetic study and the results corresponded with reference HPLC-MS/MS values. Capillary electrophoresis proved to be sensitive and selective tool for the analysis of riociguat and DMR.  相似文献   
8.
Noble-metal aerogels (NMAs) have drawn increasing attention because of their self-supported conductive networks, high surface areas, and numerous optically/catalytically active sites, enabling their impressive performance in diverse fields. However, the fabrication methods suffer from tedious procedures, long preparation times, unavoidable impurities, and uncontrolled multiscale structures, discouraging their developments. By utilizing the self-healing properties of noble-metal aggregates, the freezing-promoted salting-out behavior, and the ice-templating effect, a freeze–thaw method is crafted that is capable of preparing various hierarchically structured noble-metal gels within one day without extra additives. In light of their cleanliness, the multi-scale structures, and combined catalytic/optical properties, the electrocatalytic and photoelectrocatalytic performance of NMAs are demonstrated, which surpasses that of commercial noble-metal catalysts.  相似文献   
9.
10.
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