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   669篇
  免费   30篇
  国内免费   8篇
化学   487篇
晶体学   3篇
力学   24篇
数学   85篇
物理学   108篇
  2023年   7篇
  2022年   11篇
  2021年   31篇
  2020年   24篇
  2019年   19篇
  2018年   21篇
  2017年   11篇
  2016年   27篇
  2015年   22篇
  2014年   27篇
  2013年   51篇
  2012年   39篇
  2011年   41篇
  2010年   25篇
  2009年   26篇
  2008年   46篇
  2007年   41篇
  2006年   35篇
  2005年   31篇
  2004年   24篇
  2003年   13篇
  2002年   21篇
  2001年   7篇
  2000年   9篇
  1999年   6篇
  1998年   9篇
  1997年   5篇
  1996年   8篇
  1995年   6篇
  1994年   7篇
  1993年   3篇
  1992年   1篇
  1991年   3篇
  1990年   5篇
  1988年   3篇
  1987年   2篇
  1986年   1篇
  1985年   5篇
  1984年   7篇
  1983年   3篇
  1982年   5篇
  1981年   7篇
  1980年   1篇
  1979年   1篇
  1978年   2篇
  1975年   1篇
  1972年   2篇
  1971年   1篇
  1962年   2篇
  1956年   1篇
排序方式: 共有707条查询结果,搜索用时 609 毫秒
1.
2.
In view of the growing interest for non-destructive tests of materials, geodynamical monitoring and in general remote sensing, there is a great effort to bring practical optical sensors from research labs to industrial and environmental applications. In this paper, we employ digital holographic technique as an efficient tool for evaluating the strain measurement capability of fiber Bragg gratings (FBG). A cantilever beam has been employed as a test structure under loading test. The strain measurements results obtained by fiber-based sensors have been compared to those obtained by using full-field digital holographic technique and point-wise strain gauge sensors glued on the same cantilever beam. A simple theoretical model is also presented to interpret and compare the experimental results coming from different techniques.  相似文献   
3.
The paper contains an axiomatic treatment of the intuitionistic theory of hereditarily finite sets, based on an induction axiom-schema and a finite set of single axioms. The main feature of the principle of induction used (due to Givant and Tarski) is that it incorporates Foundation. On the analogy of what is done in Arithmetic, in the axiomatic system selected the transitive closure of the membership relation is taken as a primitive notion, so as to permit an immediate adaptation of the theory to cases of restricted induction (in particular primitive recursive induction). At the end of the paper several different forms of induction, which play an important role in the development of the theory, are compared. An alternative axiomatization of the theory, which is of intrinsic interest, is also discussed.  相似文献   
4.
We first compare the mathematical structure of quantum and classical mechanics when both are formulated in a C*-algebraic framework. By using finite von Neumann algebras, a quantum mechanical analogue of Liouville's theorem is then proposed. We proceed to study Poincaré recurrence in C*-algebras by mimicking the measure theoretic setting. The results are interpreted as recurrence in quantum mechanics, similar to Poincaré recurrence in classical mechanics.  相似文献   
5.
This paper describes the formation of a self-assembled monolayer of 11-mercaptoundecanoic acid (MUA) under different concentrations on a gold sensor disk, monitoring in situ and in real time using surface plasmon resonance spectroscopy (SPR). The film thickness and dielectric constant were determined for a fully formed monolayer using one-color approach SPR. The kinetic studies of the film formation in ethanol solution indicated that the self-assembled monolayer is formed in a two-step adsorption process. In this sense, this unpublished route was applied on the basis of a model where many molecules are adsorbed at an initial step and then can be desorbed and/or rearranged to form a perfect monolayer.  相似文献   
6.
The rate constant of intramolecular electron transfer through oligopeptides based on the alpha-aminoisobutyric acid residue was determined as a function of the peptide length and found to depend weakly on the donor-acceptor separation. By measuring the electron-transfer activation energy and estimating the energy gap between donor and bridge, we were able to discard the electron hopping mechanism.  相似文献   
7.
Summary The halogen bridges of the dimeric, cyclometallated trimesityl-arsine and -phosphine complexes of palladium(II) and platinum(II), where M=Pd or Pt and E=P or As have been replaced with pyrazolate groups to give the corresponding and less symmetric pyrazolato-bridged complexes, where M=Pd or Pt, E=P or As, Pz=pyrazolato anion, and M=Pd, E=As, Pz=3,5-dimethylpyrazolato anion. In the case of the palladium complexes,1H. n.m.r. clearly indicates the presence of only one isomer which is most likely to have thetrans configuration while the platinum complexes are mixtures of bothcis andtrans forms.Part VI, ref. 3c  相似文献   
8.
In an approach to SRS-A and analogues thereof, the key (5S, 6S)-epoxy alcohol 9 and its 6-epimer 18 were prepared starting from D-araboascorbic acid and L-diethyl tartrate, respectively.  相似文献   
9.
Dissociative electron transfers (ET) are reactions in which the ET is associated with the cleavage of a sigma bond. Although a rather satisfactory amount of information is currently available on the intermolecular and heterogeneous dissociative ET reactions, less is known for the corresponding intramolecular processes, despite the relevance of these reactions in both chemistry and biochemistry. This tutorial review focuses on the most recent developments in this area, with particular emphasis on the reactions occurring in well-defined Donor-Spacer-Acceptor molecular systems. The goal is to provide the reader with the essential background to understand and possibly predict the feasibility and rates of these reactions, as well as to stimulate the application of the intramolecular dissociative ET concepts and related issues to still unexplored molecular systems.  相似文献   
10.
A high-affinity ligand of cholera toxin, the divalent glycocalix[4]arene 1, was obtained by exploiting a combination of structure-based design of glycomimetic monovalent ligands and affinity enhancements by multivalent presentation through a calix[4]arene scaffold. It exhibits a slightly higher affinity for the toxin than its natural ligand, the GM1 oligosaccharide.  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