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   178173篇
  免费   2673篇
  国内免费   399篇
化学   99740篇
晶体学   1914篇
力学   7162篇
综合类   16篇
数学   19144篇
物理学   53269篇
  2021年   1285篇
  2020年   1569篇
  2019年   1594篇
  2018年   2096篇
  2017年   2016篇
  2016年   3530篇
  2015年   2396篇
  2014年   3280篇
  2013年   8096篇
  2012年   6881篇
  2011年   8321篇
  2010年   5467篇
  2009年   5228篇
  2008年   7444篇
  2007年   7472篇
  2006年   6903篇
  2005年   6352篇
  2004年   5509篇
  2003年   4681篇
  2002年   4633篇
  2001年   4879篇
  2000年   3777篇
  1999年   2910篇
  1998年   2485篇
  1997年   2369篇
  1996年   2276篇
  1995年   2085篇
  1994年   2021篇
  1993年   1913篇
  1992年   2157篇
  1991年   2205篇
  1990年   1989篇
  1989年   1977篇
  1988年   1926篇
  1987年   1820篇
  1986年   1755篇
  1985年   2314篇
  1984年   2414篇
  1983年   1966篇
  1982年   2138篇
  1981年   2020篇
  1980年   1922篇
  1979年   2096篇
  1978年   2246篇
  1977年   2111篇
  1976年   2156篇
  1975年   2069篇
  1974年   2111篇
  1973年   2120篇
  1972年   1377篇
排序方式: 共有10000条查询结果,搜索用时 906 毫秒
51.
52.
In the last decade, catalytic chemical vapor deposition (CVD) has been intensively explored for the growth of single-layer graphene (SLG). Despite the scattering of guidelines and procedures, variables such as the surface texture/chemistry of catalyst metal foils, carbon feedstock, and growth process parameters have been well-scrutinized. Still, questions remain on how best to standardize the growth procedure. The possible correlation of procedures between different CVD setups is an example. Here, two thermal CVD reactors were explored to grow graphene on Cu foil. The design of these setups was entirely distinct, one being a “showerhead” cold-wall type, whereas the other represented the popular “tubular” hot-wall type. Upon standardizing the Cu foil surface, it was possible to develop a procedure for cm2-scale SLG growth that differed only by the carrier gas flow rate used in the two reactors.  相似文献   
53.
Journal of Solid State Electrochemistry - In this work, the use of neodymium electrodes as a basis for the immobilization of magnetite nanoparticles has been carried out. The sensitivity and...  相似文献   
54.
55.
Molecular dynamics simulation was performed to study the formation of cluster structure, interfaces, and surfaces with different curvature radii in a perfect nanocrystal passed through by a nonlinear wave. It is shown that this process is a type of nanostructure self-organization in response to an external energy flux with subsequent development of a strong rotational field.  相似文献   
56.
Echabaane  M.  Hfaiedh  S.  Smiri  B.  Saidi  F.  Dridi  C. 《Journal of Solid State Electrochemistry》2021,25(6):1797-1806
Journal of Solid State Electrochemistry - The fast and sensitive detection of copper ions would be essential for water monitoring. Herein, we report a novel development of an impedimetric sensor...  相似文献   
57.
Journal of Thermal Analysis and Calorimetry - Novel porous carbon sheets were developed as green, renewable, cost-effective, and efficient flame retardant material for thermoplastic polymers....  相似文献   
58.
Journal of Thermal Analysis and Calorimetry - The paper focuses on the analytical analysis of the propagation of a normal shock wave in an adiabatic gas flow with nanoparticles. A modified...  相似文献   
59.
Journal of Solid State Electrochemistry - In this study, galvanostatic electrolysis, through the use of the platinum supported on Ti (Ti/Pt) and Ti/TiO2-nanotubes/PbO2 anodes, was conducted in an...  相似文献   
60.
A new derivative of dioxouranium(VI) salen complex, [UO2(L)(pyridine)], where [L = N,N′-Bis(2-hydroxybenzylidene)-2,2-dimethyl-1,3-propanediamine] is synthesized and characterized by elemental analysis (C, H, N), FT-IR, ESI-MS spectrometry, UV/Vis, fluorescence, 1H and 13C NMR spectroscopy and thermal gravimetric (TG) study. Furthermore, the single crystal X-ray diffraction measurements of the complex were carried out at 100 and 273 K. The crystal structure measurements revealed that the complex has distorted pentagonal bipyramidal geometry with uranium atom located at the centre and bonded to two phenoxy oxygen and two azomethine nitrogen in tetradenate fashion and one nitrogen from pyridine making it seven coordinated. In addition, the photoluminescence property of the complex was also recorded.  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