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   1387503篇
  免费   30136篇
  国内免费   7766篇
化学   701842篇
晶体学   19904篇
力学   75325篇
综合类   108篇
数学   250079篇
物理学   378147篇
  2021年   13747篇
  2020年   16233篇
  2019年   16475篇
  2016年   28433篇
  2015年   21428篇
  2014年   31311篇
  2013年   76178篇
  2012年   41298篇
  2011年   39012篇
  2010年   38100篇
  2009年   39999篇
  2008年   37865篇
  2007年   33351篇
  2006年   40573篇
  2005年   31670篇
  2004年   32779篇
  2003年   30628篇
  2002年   31737篇
  2001年   30754篇
  2000年   26411篇
  1999年   23409篇
  1998年   21580篇
  1997年   21493篇
  1996年   21634篇
  1995年   19571篇
  1994年   19114篇
  1993年   18737篇
  1992年   18785篇
  1991年   18854篇
  1990年   18069篇
  1989年   18061篇
  1988年   17629篇
  1987年   17510篇
  1986年   16505篇
  1985年   22968篇
  1984年   24110篇
  1983年   20214篇
  1982年   21951篇
  1981年   21151篇
  1980年   20467篇
  1979年   20682篇
  1978年   21972篇
  1977年   21535篇
  1976年   21263篇
  1975年   19991篇
  1974年   19687篇
  1973年   19946篇
  1972年   14373篇
  1968年   12366篇
  1967年   12713篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Russian Journal of Applied Chemistry - In September 1975, the head of Russian electrochemists, Academician A.N. Frumkin (1895–1976), in his report at the XI Mendeleev Congress on General and...  相似文献   
52.
Theoretical and Mathematical Physics - We study a phenomenological model in which dark matter in the cosmological constant form is identified with the mean energy–momentum tensor of a...  相似文献   
53.
Russian Journal of General Chemistry - Tungstophosphatozincates with the Keggin anion structure Kt5[PW11O39Zn(H2O)]?nH2O, Kt = Rb+, Cs+, (CH3)4N+; (C2H5)4N+ were synthesized. Their...  相似文献   
54.
Russian Journal of General Chemistry - The review article traces the main trends of the synthetic approach to the solution of the problem of overcoming the resistance of pathogenic bacterial...  相似文献   
55.
56.
Makarov  G. N. 《JETP Letters》2022,115(11):660-666
JETP Letters - Using the spectroscopic data on the 235UF6 and 238UF6 molecules and on the lasing frequencies of CF4 and para-H2 lasers and recent results, a method has been proposed to increase the...  相似文献   
57.
Knyazev  Yu. V.  Kazak  N. V.  Gavrichkov  V. A.  Polukeev  S. I.  Ovchinnikov  S. G. 《JETP Letters》2022,116(8):567-573
JETP Letters - Changes in the magnetic properties of FeBO3 single crystals in the course of spin crossover occurring with increasing pressure up to 63 GPa are studied both experimentally and...  相似文献   
58.
Chemistry of Heterocyclic Compounds - 2-Imino-2,5-dihydrofurans are a highly valuable class of heterocyclic compounds that show versatile biological activity and are used in diverse fields of...  相似文献   
59.
Low-flow chromatography has a rich history of innovation but has yet to reach widespread implementation in bioanalytical applications. Improvements in pump technology, microfluidic connections, and nano-electrospray sources for MS have laid the groundwork for broader application, and innovation in this space has accelerated in recent years. This article reviews the instrumentation used for nano-flow LC, the types of columns employed, and strategies for multidimensionality of separations, which are key to the future state of the technique to the high-throughput needs of modern bioanalysis. An update of the current applications where nano-LC is widely used, such as proteomics and metabolomics, is discussed. But the trend toward biopharmaceutical development of increasingly complex, targeted, and potent therapeutics for the safe treatment of disease drives the need for ultimate selectivity and sensitivity of our analytical platforms for targeted quantitation in a regulated space. The selectivity needs are best addressed by mass spectrometric detection, especially at high resolutions, and exquisite sensitivity is provided by nano-electrospray ionization as the technology continues to evolve into an accessible, robust, and easy-to-use platform.  相似文献   
60.
The designs of efficient and inexpensive Pt-based catalysts for methanol oxidation reaction (MOR) are essential to boost the commercialization of direct methanol fuel cells. Here, the highly catalytic performance PtFe alloys supported on multiwalled carbon nanotubes (MWCNTs) decorating nitrogen-doped carbon (NC) have been successfully prepared via co-engineering of the surface composition and electronic structure. The Pt1Fe3@NC/MWCNTs catalyst with moderate Fe3+ feeding content (0.86 mA/mgPt) exhibits 2.26-fold enhancement in MOR mass activity compared to pristine Pt/C catalyst (0.38 mA/mgPt). Furthermore, the CO oxidation initial potential of Pt1Fe3@NC/MWCNTs catalyst is lower relative to Pt/C catalyst (0.71 V and 0.80 V). Benefited from the optimal surface compositions, the anti-corrosion ability of MWCNT, strong electron interaction between PtFe alloys and MWCNTs and the N-doped carbon (NC) layer, the Pt1Fe3@NC/MWCNTs catalyst presents an improved MOR performance and anti-CO poisoning ability. This study would open up new perspective for designing efficient electrocatalysts for the DMFCs field.  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