全文获取类型
收费全文 | 536篇 |
免费 | 10篇 |
国内免费 | 1篇 |
专业分类
化学 | 226篇 |
晶体学 | 5篇 |
力学 | 97篇 |
数学 | 36篇 |
物理学 | 77篇 |
无线电 | 106篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 6篇 |
2020年 | 10篇 |
2019年 | 23篇 |
2018年 | 23篇 |
2017年 | 23篇 |
2016年 | 14篇 |
2015年 | 31篇 |
2014年 | 17篇 |
2013年 | 21篇 |
2012年 | 24篇 |
2011年 | 24篇 |
2010年 | 35篇 |
2009年 | 25篇 |
2008年 | 24篇 |
2007年 | 21篇 |
2006年 | 32篇 |
2005年 | 44篇 |
2004年 | 28篇 |
2003年 | 32篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 5篇 |
1997年 | 10篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 7篇 |
1978年 | 1篇 |
1975年 | 2篇 |
1968年 | 1篇 |
排序方式: 共有547条查询结果,搜索用时 15 毫秒
1.
2.
《Comptes Rendus Physique》2016,17(7):685-692
Quantum Zeno Dynamics restricts the evolution of a system in a tailorable subspace of the Hilbert space by repeated measurements of a proper observable. This restricted dynamics can be counterintuitive and lead to the generation of interesting nonclassical states. We describe an experiment implementing the Zeno dynamics in an atomic Rydberg level manifold, and we propose an implementation in the cavity quantum electrodynamics context. Both systems open promising perspectives for quantum-enabled metrology and decoherence studies. 相似文献
3.
一种基于TS201的归一化互相关快速算法 总被引:2,自引:0,他引:2
归一化互相关算法因其图像匹配稳定性高的特点被广泛应用于SAR成像和红外成像的制导系统中。为增强其应用的实时性,讨论一种基于TS201处理器,在保证全图遍历条件下,结合处理器的自身特性,采用递推与多模板思想构建的归一化互相关快速算法。实验证明,该执行效率常规算法的实现方案有了很大提高,可以实现低对比度条件下的目标精确匹配。 相似文献
4.
从工艺需求、成本、工期与污染控制的角度出发,检视目前面板厂建厂的设计概念后,提出另外一种LTPS建厂设计的提案构想,以为业界参考。 相似文献
5.
6.
M.E. Kletskii A.A. Millov A.V. Metelitsa M.I. Knyazhansky 《Journal of photochemistry and photobiology. A, Chemistry》1997,110(3):857-270
The mechanism of light-induced transformation in the salicylideneaniline molecule was studied by semiempirical PM3 calculations. The structures and energies of the minima and saddle points (transition states) on the S0, S1 and T1 potential energy hypersurfaces (PESs) were obtained, together with the gradient lines on the PESs. The structure-energy scheme was compared with the experimental findings. According to the results obtained, the following principle processes are observed: fast S1 excited state intramolecular proton transfer (ESIPT), followed by typical ESIPT fluorescence; the formation of two S1 twisted intramolecular charge transfer (TICT) structures which quench the ESIPT fluorescence; the diabatic formation of two ground state metastable coloured “post-TICT” structures responsible for photochromism. 相似文献
7.
The last two decades have seen a dramatic development in the study of metal-metal multiple bonds, particular successes being recorded in the field of organometallic chemistry. Syntheses designed to produce novel transition metal complexes with single, double, triple and quadruple metal-metal bonds occupy a most important place in such research, as also do reactivity studies. A striving to establish general principles has provided much of the motivation for such work, but one less obvious goal—the commercial application of the catalytic properties of metal-metal multiple bonding systems, in the medium and long term—should not be overlooked. All aspects of the investigations of metal-metal multiple bonds also apply to a particular class of compound that has, however, enjoyed little lime-light and thus deserves the present review: complexes with multiple bonds between transition metals and substituent-free (“bare”) main group elements. Although based mostly on accidental discoveries, the few noteworthy examples are now beginning to unfold general concepts of synthesis that are capable of being extended and thus are deserving of exploitation in preparative chemistry. The availability of further structural patterns exhibiting multiple bonds between transition metals and ligand-free main group elements might enable preparative organometallic chemistry to expand in a completely new direction (for instance by the stabilizing or activation of small molecules at the metal complex). This essay discusses the chemistry of complexes of bare carbon, nitrogen, and oxygen ligands (carbido-, nitrido-, and oxo-complexes) and their relationships to higher homologues from both a synthetic and a structural point of view. 相似文献
8.
Jun Araki Kousaku Ohkawa Yusuke Uchida Yoshihiko Murakami 《Journal of polymer science. Part A, Polymer chemistry》2012,50(3):488-494
A sliding graft copolymer (SGC) with poly(ethylene glycol) (PEG) side chains was prepared by ester formation between terminal carboxyl groups of oxidized PEG methyl ether with molecular weight of 2000 (mPEG2000‐COOH) and hydroxyl groups of a polyrotaxane consisting of PEG and cyclodextrins (CDs). Formation of the SGC structure was confirmed by 1H NMR, attenuated total reflectance Fourier‐transformed infrared, and gel permeation chromatography. The SGC was soluble in good solvents of PEG and insoluble in poor solvents of PEG. Estimation of the number of grafted mPEG chains suggested a “rope‐curtain” like structure, in which an mPEG chain is connected to each CD ring. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
9.
10.
L. S. Ettre 《Journal of separation science》1985,8(9):497-503
This paper briefly surveys three important considerations related to the tube diameter and film thickness. These are the interrelationship of these two parameters through the phase ratio, the different meanings of the term “efficiency”, and the influence of film thickness and tube diameter on sample capacity. Comparative examples are given for columns having different diameters and film thicknesses. 相似文献