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   1275033篇
  免费   35181篇
  国内免费   13201篇
化学   631950篇
晶体学   14742篇
力学   75278篇
综合类   493篇
数学   240083篇
物理学   360869篇
  2021年   14387篇
  2020年   16953篇
  2019年   17288篇
  2016年   28221篇
  2015年   21936篇
  2014年   32146篇
  2013年   76506篇
  2012年   36934篇
  2011年   30896篇
  2010年   36950篇
  2009年   40037篇
  2008年   30867篇
  2007年   25160篇
  2006年   33500篇
  2005年   24347篇
  2004年   26557篇
  2003年   25759篇
  2002年   27385篇
  2001年   24925篇
  2000年   22788篇
  1999年   21831篇
  1998年   20929篇
  1997年   20483篇
  1996年   19245篇
  1995年   18632篇
  1994年   18126篇
  1993年   17543篇
  1992年   16991篇
  1991年   17296篇
  1990年   16550篇
  1989年   16599篇
  1988年   16174篇
  1987年   16227篇
  1986年   15082篇
  1985年   21649篇
  1984年   23092篇
  1983年   19287篇
  1982年   21079篇
  1981年   20328篇
  1980年   19624篇
  1979年   19738篇
  1978年   21179篇
  1977年   20775篇
  1976年   20461篇
  1975年   19127篇
  1974年   18743篇
  1973年   19286篇
  1972年   13818篇
  1968年   11858篇
  1967年   12251篇
排序方式: 共有10000条查询结果,搜索用时 670 毫秒
11.
Bo  Luo  Gao  Wei  Yu  Yuguo  Chen  Xiaojun 《Nonlinear dynamics》2022,110(1):281-311
Nonlinear Dynamics - The perovskite solar cell (PSC) is one of the most promising photovoltaic candidates along with the highly increasing demand for green electricity. One of the main concerns...  相似文献   
12.
Nikolaev  N. N. 《JETP Letters》2022,115(11):639-643
JETP Letters - A new approach to search for axions in the storage ring experiments, applicable at a short coherence time of the in-plane polarization as is the case for protons is discussed. The...  相似文献   
13.
Lin  Yu  Wu  Yeyu  Tan  Xuecai  Wu  Jiawen  Huang  Kejing  Mi  Yan  Ou  Panpan  Wei  Fucun 《Journal of Solid State Electrochemistry》2022,26(4):959-971
Journal of Solid State Electrochemistry - An ultrasensitive “signal-off–on” electrochemiluminescence (ECL) biosensor is constructed based on f1-TiO2/g-C3N4/PDA for thrombin...  相似文献   
14.
Mathematical Programming - We provide a control-theoretic perspective on optimal tensor algorithms for minimizing a convex function in a finite-dimensional Euclidean space. Given a function...  相似文献   
15.
The artificially accurate design of nonmetal electrocatalysts’ active site has been a huge challenge because no pure active species with the specific structure could be strictly controlled by traditional synthetic methods. Species with a multiconfiguration in the catalyst hinder identification of the active site and the subsequent comprehension of the reaction mechanism. We have developed a novel electro-assisted molecular assembly strategy to obtain a pure pentagon ring on perfect graphene avoiding other reconstructed structures. More importantly, the active atom was confirmed by the subtle passivation process as the topmost carbon atom. Recognition of the carbon-defect electrocatalysis reaction mechanism was first downsized to the single-atom scale from the experimental perspective. It is expected that this innovative electro-assisted molecular assembly strategy could be extensively applied in the active structure-controlled synthesis of nonmetal electrocatalysts and verification of the exact active atom.  相似文献   
16.
Russian Journal of General Chemistry - Aminophosphabetaines, i.e., isobutyl {[alkyl(dimethyl)ammonio]methyl}phosphonates with higher alkyl substituents at the nitrogen atom, were obtained by a...  相似文献   
17.
The coordination chemistry of f-block elements (lanthanide and actinide) in molten salts has become a resounding topic in view of its great importance to the research and development (R&D) of molten salt reactors and pyroprocessing. In this Review article, a general overview of the coordination chemistry of f-block elements in molten salts is provided including past achievements and recent advances. Particular emphases are placed on the oxidation state, speciation, and solution structure of f-block metal ions in molten salts, as well as their relationships with the salt composition. Furthermore, this review briefly discusses the spectroscopic and theoretical methods that complement each other in revealing the coordination properties.  相似文献   
18.
19.
Chemistry of Natural Compounds - O- and N-propylamino-derivatives of betulin and betulonic acid oxime and methyl ester were synthesized. Their antitumor activity against a panel of 60 human cancer...  相似文献   
20.
Thin films with a nanometer-scale thickness are of great interest to both scientific and industrial communities due to their numerous applications and unique behaviors different from the bulk. However, the understanding of thin-film mechanics is still greatly hampered due to their intrinsic fragility and the lack of commercially available experimental instruments. In this review, we first discuss the progression of thin-film mechanical testing methods based on the supporting substrate: film-on-solid substrate method, film-on-water tensile tests, and water-assisted free-standing tensile tests. By comparing past studies on a model polymer, polystyrene, the effect of different substrates and confinement effect on the thin-film mechanics is evaluated. These techniques have generated fruitful scientific knowledge in the field of organic semiconductors for the understanding of structure–mechanical property relationships. We end this review by providing our perspective for their bright prospects in much broader applications and materials of interest.  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