全文获取类型
收费全文 | 30182篇 |
免费 | 1648篇 |
国内免费 | 1573篇 |
专业分类
化学 | 7649篇 |
晶体学 | 135篇 |
力学 | 1014篇 |
综合类 | 202篇 |
数学 | 3157篇 |
物理学 | 5193篇 |
综合类 | 16053篇 |
出版年
2024年 | 46篇 |
2023年 | 223篇 |
2022年 | 478篇 |
2021年 | 528篇 |
2020年 | 532篇 |
2019年 | 540篇 |
2018年 | 484篇 |
2017年 | 564篇 |
2016年 | 650篇 |
2015年 | 746篇 |
2014年 | 1243篇 |
2013年 | 1596篇 |
2012年 | 1478篇 |
2011年 | 1640篇 |
2010年 | 1293篇 |
2009年 | 1687篇 |
2008年 | 1778篇 |
2007年 | 2027篇 |
2006年 | 1870篇 |
2005年 | 1554篇 |
2004年 | 1398篇 |
2003年 | 1333篇 |
2002年 | 1277篇 |
2001年 | 1084篇 |
2000年 | 966篇 |
1999年 | 817篇 |
1998年 | 594篇 |
1997年 | 515篇 |
1996年 | 412篇 |
1995年 | 395篇 |
1994年 | 354篇 |
1993年 | 320篇 |
1992年 | 399篇 |
1991年 | 270篇 |
1990年 | 216篇 |
1989年 | 198篇 |
1988年 | 189篇 |
1987年 | 175篇 |
1986年 | 114篇 |
1985年 | 90篇 |
1984年 | 80篇 |
1983年 | 50篇 |
1982年 | 96篇 |
1981年 | 171篇 |
1980年 | 182篇 |
1979年 | 184篇 |
1978年 | 164篇 |
1977年 | 101篇 |
1976年 | 108篇 |
1973年 | 77篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
S.-Y. Sheu D.-Y. Yang H.L. Selzle E.W. Schlag 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):557-563
Charge transport is one important example of signal transduction in a protein which is responsible for action at a distance,
and is a fundamental process in biochemical action. A model is presented in which electronic effects interact with motional
processes to combine into a bifunctional model. This model is investigated with new detailed molecular dynamics calculations
and successfully explains such action at a distance.
Received 1st February 2002 / Received in final form 26 May 2002 Published online 13 September 2002 相似文献
32.
Most of the novel highly potent drugs, developed on the basis of modern molecular medicine, taking into account cell surface recognition techniques, show poor water solubility. A chemical modification of the drug substance enhancing the solubility often decreases the pharmacological activity. Thus, as an alternative an increase of the solubility can be obtained by the reduction of the size of the drug particles. Unfortunately, it is often difficult to obtain micro or nanosized drug particles by classical or more advanced crystallization using supercritical gases or by milling techniques. In addition, nanosized particles are often not physically stable and need to be stabilized in an appropriate matrix. Thus, it may be of interest to manufacture directly nanosized drug particles stabilized in an inert hydrophilic matrix, i.e. nanostructured and nanocomposite systems. Solid solutions and solid dispersions represent nanostructured and nanocomposite systems. In this context, the use of the vacuum-fluidized-bed technique for the spray-drying of a low water soluble drug cosolubilized with a hydrophilic excipient in a polar organic solvent is discussed. In order to avoid the use of organic solvents, a special spray-freeze-drying technique working at atmospheric pressure is presented. This process is very suitable for temperature and otherwise sensitive drugs such as pharmaproteins. 相似文献
33.
两种拔尿管方法对膀胱功能损伤的临床观察 总被引:2,自引:0,他引:2
为观察两种不同的拔尿管方法对膀胱功能损伤的差异,将80例患者随机分成两组,分别采用改良法(40例)和常规法(40例)拔除留置尿管,分析比较了两组患者排尿顺利率、逼尿肌功能恢复率及尿道刺激症、尿失禁、尿潴留。结果表明,两组患者拔管后上述指标与情况有显著性差异,P<0.05。提示改良组膀胱功能损伤明显低于对照组。改良的拔管方法是一种值得护理推广应用的好方法。 相似文献
34.
为探讨穴位注射维生素B1佐治小儿腹泻的价值,对1995~2000年收治的178例小儿腹泻患者进行足三里穴位注射维生素B1治疗100例(观察组)与常规治疗78例进行对照,结果两组止泻天数间有显著差异(P<0.01). 相似文献
35.
高淑云 《上饶师范学院学报》2002,22(4):63-65
私营企业是党的建设的重要领域,私营企业中的党组织如何正确处理与企业主的关系,是目前党建工作中的一个薄弱环节,也是迫切需要研究探索的一个重要课题,本文积极探索,寻求这方面的路径及规律。 相似文献
36.
37.
铝合金加工用刀具的使用研究(三) 总被引:2,自引:0,他引:2
当前我国各机械加工生产厂家引进国外进口设备及生产线较多,实现引进设备及生产线上刀具的国产化以降低生产成本,成为当前国内整个机械加工领域亟待解决的问题。 相似文献
38.
A Dirac picture perturbation theory is developed for the time evolution operator in classical dynamics in the spirit of the Schwinger–Feynman–Dyson perturbation expansion and detailed rules are derived for computations. Complexification formalisms are given for the time evolution operator suitable for phase space analyses, and then extended to a two-dimensional setting for a study of the geometrical Berry phase as an example. Finally a direct integration of Hamilton's equations is shown to lead naturally to a path integral expression, as a resolution of the identity, as applied to arbitrary functions of generalized coordinates and momenta. 相似文献
39.
K. Batra V. Prasad M. Mohan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(2):191-198
The scattering of heavy ion with a multilevel Rydberg atom in the presence of an electromagnetic field is studied. The interaction
of Rydberg atom and the e.m field is explored using non-perturbative quasi-energy technique. Although the results are presented
for selected excitations but in actual calculations we have included many levels of the atom. The effect of various parameters
are shown on collisional excitation process. As an illustration detailed calculations are performed for the inelastic proton-Na
Rydberg atom collision accompanied by the transfer of photons and the effects of dressing due to the field are considered.
The emphasis of the present work is on collision induced transitions especially the case that involves change of orbital as
well as principal quantum number.
Received 26 December 2001 / Received in final form 8 April 2002 Published online 19 July 2002 相似文献
40.
本文进一步分析了SW规约下的SW度结构的一些性质,得到了强可计算实数的两个性质.并且证明了给定可计算可枚举实数,可构造出sw归约下不小于该数的低的可计算可枚举实数. 相似文献