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   74565篇
  免费   11068篇
  国内免费   7863篇
化学   51097篇
晶体学   762篇
力学   4899篇
综合类   621篇
数学   9404篇
物理学   26713篇
  2024年   61篇
  2023年   1421篇
  2022年   1463篇
  2021年   2165篇
  2020年   2719篇
  2019年   2627篇
  2018年   2339篇
  2017年   2116篇
  2016年   3219篇
  2015年   3289篇
  2014年   3924篇
  2013年   5223篇
  2012年   6402篇
  2011年   6689篇
  2010年   4593篇
  2009年   4503篇
  2008年   4756篇
  2007年   4248篇
  2006年   4039篇
  2005年   3527篇
  2004年   2839篇
  2003年   2210篇
  2002年   1953篇
  2001年   1781篇
  2000年   1528篇
  1999年   1658篇
  1998年   1402篇
  1997年   1200篇
  1996年   1236篇
  1995年   1117篇
  1994年   1042篇
  1993年   900篇
  1992年   803篇
  1991年   708篇
  1990年   589篇
  1989年   502篇
  1988年   390篇
  1987年   366篇
  1986年   320篇
  1985年   324篇
  1984年   206篇
  1983年   183篇
  1982年   155篇
  1981年   117篇
  1980年   87篇
  1978年   60篇
  1977年   53篇
  1976年   51篇
  1975年   61篇
  1973年   58篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Circularly polarized luminescence (CPL) has attracted attention as a next-generation light signal because of its carrying more information compared with normal and linearly polarized lights as well as its potential wide application in information fields. Recently, much attention has been paid to small organic molecules-based CPL emitters because of easy synthesis, fine structural modification at molecular level, and tunable wide range emission wavelength. This review highlights the development of small organic molecules-based CPL emitters in the past 5 years (2017–2021). The progress suggests that small organic molecules-based CPL emitters provide a simple and efficient way to generate CPL.  相似文献   
2.
Bo  Luo  Gao  Wei  Yu  Yuguo  Chen  Xiaojun 《Nonlinear dynamics》2022,110(1):281-311
Nonlinear Dynamics - The perovskite solar cell (PSC) is one of the most promising photovoltaic candidates along with the highly increasing demand for green electricity. One of the main concerns...  相似文献   
3.
Acta Mathematica Sinica, English Series - We are interested in the existence and asymptotic behavior for the least energy solutions of the following fractional eigenvalue problem $$\left({\rm{P}}...  相似文献   
4.
Science China Chemistry - Human health is always under global spotlight, but now it suffers from severe environmental issue and various diseases. Developing highly selective and effective...  相似文献   
5.
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   
6.
7.
陈华俊  朱鹏杰  陈咏雷  侯宝成 《中国物理 B》2022,31(2):27802-027802
We investigate theoretically Rabi-like splitting and Fano resonance in absorption spectra of quantum dots(QDs)based on a hybrid QD-semiconducting nanowire/superconductor(SNW/SC)device mediated by Majorana fermions(MFs).Under the condition of pump on-resonance and off-resonance,the absorption spectrum experiences the conversion from Fano resonance to Rabi-like splitting in different parametric regimes.In addition,the Fano resonances are accompanied by the rapid normal phase dispersion,which will indicate the coherent optical propagation.The results indicate that the group velocity index is tunable with controlling the interaction between the QD and MFs,which can reach the conversion between the fast-and slow-light.Fano resonance will be another method to detect MFs and our research may indicate prospective applications in quantum information processing based on the hybrid QD-SNW/SC devices.  相似文献   
8.
Annals of Global Analysis and Geometry - In this paper, we prove a family of sharp geometric inequalities for free boundary hypersurfaces in a ball in space forms.  相似文献   
9.
采用态平均(CASSCF)/高度相关多参考组(MRCI)方法,对N2分子A3Σu+、B3Пg、C3Пu电子态的势能、跃迁偶极矩进行了高度相关的精确计算.计算的势能在平衡位置附近与RKR拟合的势能曲线非常一致,获得的跃迁偶极矩与已有实验值符合很好。首次对A3Σu+、B3Пg、C3Пu电子态的振转光谱常数随振动量子数v的变化进行系统定量计算,其结果与已有的实验观测数据相符.同时,获得了N2分子第一正带系的0-1、0-2、1-0、1-2、1-3、2-0、2-1、2-3、3-0、3-1和3-2光谱带分别在300,3000,6000,10000K时的谱线强度,如1-0带在3000,6000,10000K时的高温谱线带强度分别为1.58543×10-16 cm-1/(分子 cm-2)、6.07889×10-17 cm-1/(分子 cm-2)和2.3781×10-17 cm-1/(分子 cm-2).这些结果对N2分子进一步的理论研究、实际应用和高温大气的建模与研究具都有一定的参考价值.  相似文献   
10.
Based on the primal mixed variational formulation, a stabilized nonconforming mixed finite element method is proposed for the linear elasticity on rectangular and cubic meshes. Two kinds of penalty terms are introduced in the stabilized mixed formulation, which are the jump penalty term for the displacement and the divergence penalty term for the stress. We use the classical nonconforming rectangular and cubic elements for the displacement and the discontinuous piecewise polynomial space for the stress, where the discrete space for stress are carefully chosen to guarantee the well-posedness of discrete formulation. The stabilized mixed method is locking-free. The optimal convergence order is derived in the $L^2$-norm for stress and in the broken $H^1$-norm and $L^2$-norm for displacement. A numerical test is carried out to verify the optimal convergence of the stabilized method.  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