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   52037篇
  免费   13224篇
  国内免费   5280篇
化学   53091篇
晶体学   641篇
力学   1691篇
综合类   273篇
数学   4320篇
物理学   10525篇
  2024年   34篇
  2023年   433篇
  2022年   643篇
  2021年   939篇
  2020年   2092篇
  2019年   3445篇
  2018年   1829篇
  2017年   1499篇
  2016年   4323篇
  2015年   4521篇
  2014年   4693篇
  2013年   5614篇
  2012年   4762篇
  2011年   4125篇
  2010年   4334篇
  2009年   4277篇
  2008年   3884篇
  2007年   3062篇
  2006年   2718篇
  2005年   2648篇
  2004年   2240篇
  2003年   1741篇
  2002年   1447篇
  2001年   1337篇
  2000年   959篇
  1999年   495篇
  1998年   364篇
  1997年   280篇
  1996年   316篇
  1995年   254篇
  1994年   200篇
  1993年   190篇
  1992年   145篇
  1991年   154篇
  1990年   105篇
  1989年   96篇
  1988年   61篇
  1987年   56篇
  1986年   54篇
  1985年   41篇
  1984年   26篇
  1983年   31篇
  1982年   15篇
  1981年   11篇
  1980年   7篇
  1979年   6篇
  1971年   4篇
  1959年   4篇
  1957年   4篇
  1936年   4篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Cheng  Hongmei  Fang  Qinhe  Xia  Yang 《Applications of Mathematics》2022,67(5):615-632
Applications of Mathematics - We focus on the free boundary problems for a Leslie-Gower predator-prey model with radial symmetry in a higher dimensional environment that is initially well populated...  相似文献   
2.
3.
In this paper, the problem of the uniform stability for a class of fuzzy fractional-order genetic regulatory networks with random discrete delays, distributed delays, and parameter uncertainties is studied. Although there is a portion of literature on using fixed point theorems to study the stability of fractional neural networks, most of them required the fractional order to be in 1 2 , 1 . However, the case of the fractional-order belonging to ( 0 , 1 2 ) has not been discussed. To solve it, this work proposes a novel idea of using fixed point theory to study the stability of fuzzy (0,1) order neural networks, the problem of the uniqueness of the solution of the considered genetic regulatory networks is resolved, and a novel sufficient condition to guarantee the uniform stability of above genetic regulatory networks is also derived. Eventually, an example is given to demonstrate that the obtained result is effective.  相似文献   
4.
Photocatalytic CO2 reduction to C1 fuels is considered to be an important way for alleviating increasingly serious energy crisis and environmental pollution. Due to the environment-friendly, simple preparation, easy formation of highly-stable metal-nitrogen(M-Nx) coordination bonds, and suitable band structure, polymeric carbon nitride-based single-atom catalysts(C3N4-based SACs) are expected to become a potential for CO2 reduction under visible-light irradiation. In this review, we summarize the recent advancement on C3N4-based SACs for photocatalytic CO2 reduction to C1 products, including the reaction mechanism for photocatalytic CO2 reduction to C1 products, the structure and synthesis methods of C3N4-based SACs and their applications toward photocatalytic CO2 reduction reaction(CO2RR) for C1 production. The current challenges and future opportunities of C3N4-based SACs for photoreduction of CO2 are also discussed.  相似文献   
5.
Journal of Solid State Electrochemistry - In this study, hot pressing was evaluated as a method of cell fabrication to increase the energy density of next-generation all-solid-state batteries with...  相似文献   
6.
Given a graph sequence denote by T3(Gn) the number of monochromatic triangles in a uniformly random coloring of the vertices of Gn with colors. In this paper we prove a central limit theorem (CLT) for T3(Gn) with explicit error rates, using a quantitative version of the martingale CLT. We then relate this error term to the well-known fourth-moment phenomenon, which, interestingly, holds only when the number of colors satisfies . We also show that the convergence of the fourth moment is necessary to obtain a Gaussian limit for any , which, together with the above result, implies that the fourth-moment condition characterizes the limiting normal distribution of T3(Gn), whenever . Finally, to illustrate the promise of our approach, we include an alternative proof of the CLT for the number of monochromatic edges, which provides quantitative rates for the results obtained in [7].  相似文献   
7.
Zhao  Tianqi  Luo  Tianzi  Fang  Bo  Shi  Lijiang  Jin  Yongxing  Zhou  Pengwei  Yao  Dong  Li  Chenxia  Jing  Xufeng  Hong  Zhi 《Journal of Russian Laser Research》2021,42(5):586-597
Journal of Russian Laser Research - The zero-refractive-index metamaterials have excellent electromagnetic properties, which provide new ideas and methods to realize the control of electromagnetic...  相似文献   
8.
Wang  Jiamin  Bi  Chongke  Deng  Liang  Wang  Fang  Liu  Yang  Wang  Yueqing 《显形杂志》2021,24(3):531-544
Journal of Visualization - In the in situ visualization of large-scale simulation, if using the traditional sort-last parallel rendering method, the performance cannot be fully improved due to the...  相似文献   
9.
International Journal of Theoretical Physics - Quantum logic gates are the foundation of circuit-based quantum computation and quantum simulation. Multi-qubit quantum controlled gates are of vital...  相似文献   
10.
Journal of Solid State Electrochemistry - A molecularly imprinted photoelectrochemical (PEC) cathodic sensor was developed for the detection of bovine serum albumin (BSA). The PEC sensor was...  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