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   5172篇
  免费   302篇
  国内免费   332篇
化学   168篇
晶体学   1篇
力学   250篇
综合类   55篇
数学   4703篇
物理学   629篇
  2024年   6篇
  2023年   56篇
  2022年   64篇
  2021年   74篇
  2020年   127篇
  2019年   164篇
  2018年   125篇
  2017年   118篇
  2016年   114篇
  2015年   115篇
  2014年   245篇
  2013年   503篇
  2012年   268篇
  2011年   337篇
  2010年   281篇
  2009年   440篇
  2008年   433篇
  2007年   332篇
  2006年   285篇
  2005年   232篇
  2004年   194篇
  2003年   209篇
  2002年   151篇
  2001年   116篇
  2000年   106篇
  1999年   99篇
  1998年   96篇
  1997年   100篇
  1996年   81篇
  1995年   56篇
  1994年   53篇
  1993年   27篇
  1992年   29篇
  1991年   19篇
  1990年   13篇
  1989年   10篇
  1988年   8篇
  1987年   6篇
  1986年   7篇
  1985年   19篇
  1984年   11篇
  1983年   10篇
  1982年   9篇
  1981年   7篇
  1980年   13篇
  1979年   4篇
  1978年   8篇
  1977年   9篇
  1976年   7篇
  1973年   4篇
排序方式: 共有5806条查询结果,搜索用时 15 毫秒
1.
《Discrete Mathematics》2022,345(10):112984
Let G be a generalized dicyclic group with identity 1. An inverse closed subset S of G?{1} is called minimal if S=G and there exists some sS such that S?{s,s?1}G. In this paper, we characterize distance-regular Cayley graphs Cay(G,S) of G under the condition that S is minimal.  相似文献   
2.
3.
In this paper, we propose a mechanism on how to construct long MDS self-dual codes from short ones. These codes are special types of generalized Reed-Solomon (GRS) codes or extended generalized Reed-Solomon codes. The main tool is utilizing additive structure or multiplicative structure on finite fields. By applying this method, more MDS self-dual codes can be constructed.  相似文献   
4.
5.
BackgroundIdentification of potential drug-target interaction pairs is very important for pharmaceutical innovation and drug discovery. Numerous machine learning-based and network-based algorithms have been developed for predicting drug-target interactions. However, large-scale pharmacological, genomic and chemical datum emerged recently provide new opportunity for further heightening the accuracy of drug-target interactions prediction.ResultsIn this work, based on the assumption that similar drugs tend to interact with similar proteins and vice versa, we developed a novel computational method (namely MKLC-BiRW) to predict new drug-target interactions. MKLC-BiRW integrates diverse drug-related and target-related heterogeneous information source by using the multiple kernel learning and clustering methods to generate the drug and target similarity matrices, in which the low similarity elements are set to zero to build the drug and target similarity correction networks. By incorporating these drug and target similarity correction networks with known drug-target interaction bipartite graph, MKLC-BiRW constructs the heterogeneous network on which Bi-random walk algorithm is adopted to infer the potential drug-target interactions.ConclusionsCompared with other existing state-of-the-art methods, MKLC-BiRW achieves the best performance in terms of AUC and AUPR. MKLC-BiRW can effectively predict the potential drug-target interactions.  相似文献   
6.
We establish the existence of solutions of the Cauchy problem for a higher-order semilinear parabolic equation by introducing a new majorizing kernel. We also study necessary conditions on the initial data for the existence of local-in-time solutions and identify the strongest singularity of the initial data for the solvability of the Cauchy problem.  相似文献   
7.
The (i) reciprocity relations for the relative Fisher information (RFI, hereafter) and (ii) a generalized RFI–Euler theorem are self-consistently derived from the Hellmann–Feynman theorem. These new reciprocity relations generalize the RFI–Euler theorem and constitute the basis for building up a mathematical Legendre transform structure (LTS, hereafter), akin to that of thermodynamics, that underlies the RFI scenario. This demonstrates the possibility of translating the entire mathematical structure of thermodynamics into a RFI-based theoretical framework. Virial theorems play a prominent role in this endeavor, as a Schrödinger-like equation can be associated to the RFI. Lagrange multipliers are determined invoking the RFI–LTS link and the quantum mechanical virial theorem. An appropriate ansatz allows for the inference of probability density functions (pdf’s, hereafter) and energy-eigenvalues of the above mentioned Schrödinger-like equation. The energy-eigenvalues obtained here via inference are benchmarked against established theoretical and numerical results. A principled theoretical basis to reconstruct the RFI-framework from the FIM framework is established. Numerical examples for exemplary cases are provided.  相似文献   
8.
This paper is concerned with the mixed initial–boundary value problem for semilinear wave equations with complementary frictional dampings and memory effects. We successfully establish uniform exponential and polynomial decay rates for the solutions to this initial–boundary value problem under much weak conditions concerning memory effects. More specifically, we obtain the exponential and polynomial decay rates after removing the fundamental condition that the memory-effect region includes a part of the system boundary, while the condition is a necessity in the previous literature; moreover, for the polynomial decay rates we only assume minimal conditions on the memory kernel function g, without the usual assumption of g controlled by g.  相似文献   
9.
We consider the question whether, given a countable family of lattices (Γj)jJ in a locally compact abelian group G, there exist functions (gj)jJ such that the resulting generalized shift-invariant system (gj(??γ))jJ,γΓj is a tight frame of L2(G). This paper develops a new approach to the study of generalized shift-invariant system via almost periodic functions, based on a novel unconditional convergence property. From this theory, we derive characterizing relations for tight and dual frame generators, we introduce the system bandwidth as a measure of the total bandwidth a generalized shift-invariant system can carry, and we show that the so-called Calderón sum is uniformly bounded from below for generalized shift-invariant frames. Without the unconditional convergence property, we show, counter intuitively, that even orthonormal bases can have arbitrary small system bandwidth. Our results show that the question of existence of frame generators for a general lattice system is rather subtle and depends on analytical and algebraic properties of the lattice system.  相似文献   
10.
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