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   1302619篇
  免费   29695篇
  国内免费   7698篇
化学   647934篇
晶体学   14389篇
力学   74160篇
综合类   104篇
数学   240833篇
物理学   362592篇
  2021年   13383篇
  2020年   15907篇
  2019年   16066篇
  2016年   27393篇
  2015年   20635篇
  2014年   30416篇
  2013年   74570篇
  2012年   36767篇
  2011年   32344篇
  2010年   35953篇
  2009年   38474篇
  2008年   32160篇
  2007年   27560篇
  2006年   35243篇
  2005年   26751篇
  2004年   28734篇
  2003年   27393篇
  2002年   28763篇
  2001年   27662篇
  2000年   24315篇
  1999年   22305篇
  1998年   20989篇
  1997年   20515篇
  1996年   19164篇
  1995年   18542篇
  1994年   18061篇
  1993年   17590篇
  1992年   17557篇
  1991年   17774篇
  1990年   17080篇
  1989年   17125篇
  1988年   16709篇
  1987年   16740篇
  1986年   15627篇
  1985年   22214篇
  1984年   23483篇
  1983年   19554篇
  1982年   21276篇
  1981年   20526篇
  1980年   19815篇
  1979年   20142篇
  1978年   21442篇
  1977年   21124篇
  1976年   20834篇
  1975年   19535篇
  1974年   19165篇
  1973年   19689篇
  1972年   14162篇
  1968年   12230篇
  1967年   12594篇
排序方式: 共有10000条查询结果,搜索用时 140 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