全文获取类型
收费全文 | 8869篇 |
免费 | 1232篇 |
国内免费 | 761篇 |
专业分类
化学 | 283篇 |
晶体学 | 5篇 |
力学 | 1329篇 |
综合类 | 336篇 |
数学 | 5784篇 |
物理学 | 3125篇 |
出版年
2024年 | 55篇 |
2023年 | 171篇 |
2022年 | 179篇 |
2021年 | 215篇 |
2020年 | 166篇 |
2019年 | 218篇 |
2018年 | 122篇 |
2017年 | 231篇 |
2016年 | 262篇 |
2015年 | 259篇 |
2014年 | 567篇 |
2013年 | 405篇 |
2012年 | 438篇 |
2011年 | 515篇 |
2010年 | 515篇 |
2009年 | 532篇 |
2008年 | 628篇 |
2007年 | 521篇 |
2006年 | 503篇 |
2005年 | 507篇 |
2004年 | 424篇 |
2003年 | 453篇 |
2002年 | 339篇 |
2001年 | 343篇 |
2000年 | 299篇 |
1999年 | 277篇 |
1998年 | 279篇 |
1997年 | 202篇 |
1996年 | 213篇 |
1995年 | 220篇 |
1994年 | 173篇 |
1993年 | 137篇 |
1992年 | 142篇 |
1991年 | 120篇 |
1990年 | 94篇 |
1989年 | 84篇 |
1988年 | 12篇 |
1987年 | 20篇 |
1986年 | 9篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1980年 | 1篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
991.
Lebesgue-Stieltjes形式的Choquet积分 总被引:1,自引:1,他引:0
首先利用Lebesgue-Stieltjes测度对Choquet积分作了推广,给出了实值可测函数的Lebesgue-Stieltjes形式的Choquet积分的定义,研究了其相应的性质;其次,本文在一定条件下研究了Lebesgue-Stieltjes形式的Choquet积分和Choquet积分的关系,得到了积分转化定理. 相似文献
992.
用超奇异积分方程法将多场耦合载荷作用下磁电热弹耦合材料内含任意形状和位置三维多裂纹问题转化为求解一以广义位移间断为未知函数的超奇异积分方程组问题,退化得到内含任意形状平行三维多裂纹问题的超奇异积分方程组;推导出平行三维多裂纹问题的裂纹前沿广义奇异应力场解析表达式、定义了广义(应力、应变能)强度因子和广义能量释放率;应用有限部积分概念及体积力法,为超奇异积分方程组建立了数值求解方法,编制了FORTRAN程序,以平行双裂纹为例,通过典型算例,研究了广义(应力、应变能)强度因子随裂纹位置、裂纹形状及材料参数变化规律,得到裂纹断裂评定准则. 最后,分析了裂纹间干扰、屏蔽作用及其在工程实际中的应用. 相似文献
993.
994.
995.
The content of thisreview consists of recent developments covering an advancedtreatment of multiple crack problems in plane elasticity. Severalelementary solutions are highlighted, which are the fundamentalsfor the formulation of the integral equations. The elementarysolutions include those initiated by point sources or by adistributed traction along the crack face. Two kinds of singularintegral equations, three kinds of Fredholm integral equations,and one kind of hypersingular integral equation are suggested forthe multiple crack problems in plane elasticity. Regularizationprocedures are also investigated. For the solution of the integralequations, the relevant quadrature rules are addressed. A varietyof methods for solving the multiple crack problems is introduced.Applications for the solution of the multiple crack problems arealso addressed. The concept of the modified complex potential(MCP) is emphasized, which will extend the solution range, forexample, from the multiple crack problem in an infinite plate tothat in a circular plate. Many multiple crack problems areaddressed. Those problems include: (i) multiple semi-infinitecrack problem, (ii) multiple crack problem with a general loading,(iii) multiple crack problem for the bonded half-planes, (iv)multiple crack problem for a finite region, (v) multiple crackproblem for a circular region, (vi) multiple crack problem inantiplane elasticity, (vii) T-stress in the multiple crackproblem, and (viii) periodic crack problem and many others. Thisreview article cites 187 references. 相似文献
996.
GUO Ying CHEN Zhi-Gang HUANG Da-Zu ZENG Gui-Hua 《理论物理通讯》2008,49(1):93-99
Exploiting the encoding process of the stabilizer quantum code [[n, k, d]], a deterministic quantum communication scheme, in which n - 1 photons are distributed forward and backward in two-way channel, is proposed to transmit the secret messages with unconditional security. The present scheme can be implemented to distribute the secret quantum (or classical) messages with great capacity in imperfect quantum channel since the utilized code encodes k-qubit messages for each scheme run. 相似文献
997.
YUAN Hao LIU Yin-Min ZHANG Wen ZHANG Zhan-Jun 《理论物理通讯》2008,49(1):103-106
Security of the quantum secure direct communication protocol (i.e., the C-S QSDC protocol) recently proposed by Cao and Song [Chin. Phys. Lett. 23 (2006) 290] is analyzed in the case of considerable quantum channel noise. The eavesdropping scheme is presented, which reveals that the C-S QSDC protocol is not secure if the quantum bit error rate (QBER) caused by quantum channel noise is higher than 4.17%. Our eavesdropping scheme induces about 4.17% QBER for those check qubits. However, such QBER can be hidden in the counterpart induced by the noisy quantum channel if the eavesdropper Eve replaces the original noisy channel by an ideal one. Furthermore, if the QBER induced by quantum channel noise is lower than 4.17%, then in the eavesdropping scheme Eve still can eavesdrop part of the secret messages by safely attacking a fraction of the transmitted qubits. Finally, an improvement on the C-S QSDC protocol is put forward. 相似文献
998.
XIE Xiao-Ning YUE Rui-Hong 《理论物理通讯》2008,49(5):1265-1268
In this paper we consider classical strings propagating in γ-deformed AdS3 × S^3 backgrounds generated by TsT transformation on the AdS3 sector, which is described as the group manifold SL(2, R), then we prove that the U(1) currents of strings with the twisted boundary conditions are equal to those in γ-deformed backgrounds. Using TsT transformation, we can derive the local Lax connection and the monodromy matrix in γ-deformed backgrounds with the spectral parameter, which ensures the classical integrability of the string theories. 相似文献
999.
JI Jie ZHANG Da-Jun ZHANG Jia-Jiang 《理论物理通讯》2008,49(5):1105-1108
In this paper, we obtain an infinite number of conservation laws for a discrete soliton system by using a solvable generalized Riccati equation. 相似文献
1000.
针对拼接式大口径望远镜主镜,提出一种基于迈克尔逊干涉原理基础上的宽带光谱(白光)干涉检测方法,对拼接子镜间相位误差进行实时检测,进而对失调子镜进行相应校正,以实现拼接子镜的共面排布。子镜间相位误差通过干涉图形间的不匹配性进行提取。应用双中心波长组合白光源来提高白光中心条纹的可见度,通过理论仿真,对不同中心波长组合的白光中心条纹可见度进行比较,结果表明:该双中心波长组合白光源系统的应用,可以提高白光干涉中心条纹的信号分辨能力,借以提高检测精度,使得该白光干涉检测系统对拼接子镜间的相位失调误差进行高精度提取。 相似文献