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   180篇
  免费   4篇
化学   67篇
晶体学   1篇
力学   2篇
数学   66篇
物理学   48篇
  2023年   1篇
  2022年   4篇
  2021年   8篇
  2020年   4篇
  2019年   4篇
  2018年   5篇
  2017年   4篇
  2016年   6篇
  2015年   8篇
  2014年   9篇
  2013年   11篇
  2012年   15篇
  2011年   12篇
  2010年   20篇
  2009年   4篇
  2008年   9篇
  2007年   10篇
  2006年   10篇
  2005年   7篇
  2004年   2篇
  2003年   2篇
  2002年   4篇
  2001年   1篇
  2000年   2篇
  1999年   1篇
  1998年   1篇
  1996年   1篇
  1993年   1篇
  1991年   1篇
  1989年   1篇
  1988年   3篇
  1985年   2篇
  1983年   2篇
  1981年   2篇
  1980年   1篇
  1979年   2篇
  1976年   1篇
  1974年   2篇
  1972年   1篇
排序方式: 共有184条查询结果,搜索用时 15 毫秒
91.
We show that the wandering of transition frequencies in colloidal quantum dots does not follow the statistics expected for ordinary diffusive processes. The trajectory of this anomalous spectral diffusion is characterized by a sqrt[t] dependence of the squared deviation. The behavior is reproduced when the electronic states of quantum dots are assumed to interact with environments such as, for example, an ensemble of two-level systems, where the correlation times are distributed according to a power law similar to the one generally attributed to the dot's luminescence intermittency.  相似文献   
92.
93.
Optical Bloch equations are widely used for describing dynamics in a system consisting molecules, electromagnetic waves, and a thermal bath. We analyze applicability of these equations to a single molecule imbedded in a solid matrix. Classical Bloch equations and the limits of their applicability are derived from more general master equations. Simple and intuitively appealing picture based on stochastic Bloch equations shows that at low temperatures, contrary to common believes, a strong driving field can not only suppress but can also increase decay rates of Rabi oscillations. A physical system where predicted effects can be observed experimentally is suggested.  相似文献   
94.
95.
Chemistry of Heterocyclic Compounds - Diversity-oriented synthesis embodied in a strategy of pairing vinyl sulfonamide moiety with other functional groups resulted in an array of skeletally diverse...  相似文献   
96.
A series of transition metal complexes involving non-innocent o-dithiolene and o-phenylenediamine ligands has been characterized in detail by various spectroscopic methods like magnetic circular dichroism (MCD), absorption (abs), resonance Raman (rR), electron paramagnetic resonance (EPR), and sulfur K-edge X-ray absorption spectroscopies. A computational model for the electronic structure of the complexes is then proposed based on the density functional theory (DFT) or ab-initio methods, which can successfully account for the observed trends in the experimental spectra (MCD, rR, and abs) of the complexes. Based on these studies, the innocent vs non-innocent nature of the ligands in a given transition metal complex is found to be dependent on the position of the central metal ion in the periodic table, its effective nuclear charge in interplay with relativistic effects.  相似文献   
97.
We prove that if an ultrafilter ${\mathcal{L}}$ is not coherent to a Q-point, then each analytic non-??-bounded topological group G admits an increasing chain ${\langle G_\alpha:\alpha < \mathfrak b(\mathcal L)\rangle}$ of its proper subgroups such that: (i) ${\bigcup_{\alpha}G_\alpha=G}$ ; and (ii) For every ??-bounded subgroup H of G there exists ?? such that ${H\subset G_\alpha}$ . In case of the group Sym(??) of all permutations of ?? with the topology inherited from ?? ?? this improves upon earlier results of S. Thomas.  相似文献   
98.
For the first time, Raman spectroscopy of α and γ polymorphs of AlH3 has been performed in the pressure range from ambient up to 16.9 and 32.7 GPa, respectively using the diamond anvil cell (DAC) technique. An analysis of pressure response wavenumbers (ν) for α‐AlH3 showed a change of dνi/dP at a pressure of about 8 GPa and may indicate a monoclinic distortion from the initially hexagonal α‐AlH3. The distortion is stable at least up to 16.9 GPa. The γ form exhibited more complex behavior transforming to the α form at a pressure of about 12 GPa. The structural phase transition was shown to be an irreversible and kinetically slow process that required at least 5 h to complete. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
99.
We prove that a locally compact ANR-space X is a Q-manifold if and only if it has the Disjoint Disk Property (DDP), all points of X are homological Z∞-points and X has the countable-dimensional approximation property (cd-AP), which means that each map f:K→X of a compact polyhedron can be approximated by a map with the countable-dimensional image. As an application we prove that a space X with DDP and cd-AP is a Q-manifold if some finite power of X is a Q-manifold. If some finite power of a space X with cd-AP is a Q-manifold, then X2 and X×[0,1] are Q-manifolds as well. We construct a countable familyχof spaces with DDP and cd-AP such that no space X∈χis homeomorphic to the Hilbert cube Q whereas the product X×Y of any different spaces X, Y∈χis homeomorphic to Q. We also show that no uncountable familyχwith such properties exists.  相似文献   
100.
We propose a new methodology for probing transport of just one electron, a process of great importance both in nature and in artificial devices. Our idea for locating a single electron is analogues to the conventional GPS where signals from several satellites are used to locate a macro object. Using fluorescent molecules as tiny sensors, it is possible to determine 3D displacement vector of an electron.  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