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   184531篇
  免费   30493篇
  国内免费   18810篇
化学   124363篇
晶体学   1887篇
力学   12541篇
综合类   978篇
数学   23055篇
物理学   71010篇
  2024年   400篇
  2023年   3374篇
  2022年   5197篇
  2021年   6178篇
  2020年   7102篇
  2019年   6781篇
  2018年   5986篇
  2017年   5523篇
  2016年   8552篇
  2015年   8186篇
  2014年   10018篇
  2013年   13307篇
  2012年   16328篇
  2011年   17196篇
  2010年   11458篇
  2009年   10998篇
  2008年   11930篇
  2007年   10822篇
  2006年   10001篇
  2005年   8353篇
  2004年   6405篇
  2003年   5021篇
  2002年   4673篇
  2001年   3883篇
  2000年   3436篇
  1999年   4019篇
  1998年   3452篇
  1997年   3266篇
  1996年   3431篇
  1995年   2874篇
  1994年   2583篇
  1993年   2131篇
  1992年   1940篇
  1991年   1701篇
  1990年   1437篇
  1989年   1073篇
  1988年   870篇
  1987年   698篇
  1986年   702篇
  1985年   580篇
  1984年   406篇
  1983年   288篇
  1982年   243篇
  1981年   191篇
  1980年   142篇
  1979年   75篇
  1978年   67篇
  1977年   69篇
  1976年   68篇
  1974年   60篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
A photoluminescent bimetallic cluster [Ag10Cu6(bdppthi)2(C≡CPh)12(MeOH)2(H2O)](ClO4)4 ( 1 , bdppthi=N,N’-bis(diphenylphosphanylmethyl)-tetrahydroimidazole} was synthesized from the PNNP type ligand bdppthi generated in-situ. Upon excitation at 365 nm, 1 exhibited strong phosphorescent emission at 630 nm, which was selectively quenched by NH3 in air or water. The sensing of NH3 was rapid and recoverable, with detection limits of 53 ppm (v/v) in N2 and 21 μmol/L (0.36 ppm, w/w) for NH3 ⋅ H2O in water. Cluster 1 could potentially serve as a bifunctional chemical sensor for the efficient detection of ammonia in waste-gas and waste-water.  相似文献   
82.
Journal of Thermal Analysis and Calorimetry - Coal O2/CO2 combustion is a promising carbon capture and storage technology for coal-fired power plant. Char consumption rate prediction is essential...  相似文献   
83.
Liu  Jian-Guo  Zhu  Wen-Hui 《Nonlinear dynamics》2020,100(3):2739-2751
Nonlinear Dynamics - Under investigation is a generalized (3 + 1)-dimensional variable- coefficient Kadomtsev– Petviashvili equation in fluid mechanics. Various exact analytical solutions are...  相似文献   
84.
The biodegradability of phtalic acid esters in marine and freshwater environments was characterized by their binding free energy with corresponding degrading enzymes. According to comprehensive biodegradation effects weights, the binding free energy values were converted into dimensionless efficacy coefficient using ratio normalization method. Then, considering comprehensive dual biodegradation effects value and the structural parameters of PAEs in both marine and freshwater environments, a 3D-QSAR pharmacophore model was constructed, five PAE derivatives (DBP−COOH, DBP−CHO, DBP−OH, DINP−NH2, and DINP−NO2) were screened out based on their environmental friendliness, functionality and stability. The prediction of biodegradation effects on five PAE derivatives by biodegradation models in marine and freshwater environment increased by 15.90 %, 15.84 %, 27.21 %, 12.33 %, and 8.32 %, and 21.57 %, 15.21 %, 20.99 %, 15.10 %, and 9.74 %, respectively. By simulating the photodegradation path of the PAE derivative molecular, it was found that DBP−OH can generate .OH and provides free radicals for the photodegradation of microplastics in the environment.  相似文献   
85.
86.
87.
88.
89.
Terahertz(THz) wave emission from argon atom in a two-color laser pulses is studied numerically by solving the one-dimensional(1D) time-dependent Schr ¨odinger equation. The THz spectra we obtained include both discontinuous and continuum ones. By using the special basis functions that we previously proposed, our analysis points out that the discontinuous and continuum parts are contributed by bound–bound and continuum–continuum transition of atomic energy levels. Although the atomic wave function is strongly dressed during the interaction with laser fields, our identification for the discontinuous part of the THz wave shows that the transition between highly excited bound states can still be well described by the field-free basis function in the tunneling ionization regime.  相似文献   
90.
Journal of Solid State Electrochemistry - The “shuttle effect” of polysulfides is a serious issue, resulting in a decrease in the life-cycle of lithium-sulfur (Li-S) batteries. To...  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