全文获取类型
收费全文 | 26335篇 |
免费 | 2323篇 |
国内免费 | 1798篇 |
专业分类
化学 | 10357篇 |
晶体学 | 126篇 |
力学 | 1508篇 |
综合类 | 417篇 |
数学 | 10702篇 |
物理学 | 7346篇 |
出版年
2023年 | 203篇 |
2022年 | 376篇 |
2021年 | 671篇 |
2020年 | 659篇 |
2019年 | 676篇 |
2018年 | 581篇 |
2017年 | 748篇 |
2016年 | 838篇 |
2015年 | 698篇 |
2014年 | 1101篇 |
2013年 | 1918篇 |
2012年 | 1202篇 |
2011年 | 1222篇 |
2010年 | 1081篇 |
2009年 | 1448篇 |
2008年 | 1622篇 |
2007年 | 1695篇 |
2006年 | 1410篇 |
2005年 | 1124篇 |
2004年 | 964篇 |
2003年 | 1018篇 |
2002年 | 1009篇 |
2001年 | 912篇 |
2000年 | 836篇 |
1999年 | 720篇 |
1998年 | 634篇 |
1997年 | 453篇 |
1996年 | 404篇 |
1995年 | 350篇 |
1994年 | 334篇 |
1993年 | 303篇 |
1992年 | 368篇 |
1991年 | 261篇 |
1990年 | 176篇 |
1989年 | 165篇 |
1988年 | 172篇 |
1987年 | 154篇 |
1986年 | 122篇 |
1985年 | 149篇 |
1984年 | 152篇 |
1983年 | 80篇 |
1982年 | 133篇 |
1981年 | 204篇 |
1980年 | 200篇 |
1979年 | 210篇 |
1978年 | 188篇 |
1977年 | 122篇 |
1976年 | 121篇 |
1973年 | 88篇 |
1972年 | 42篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
We present a new approach to study the convergence of Newton's method in Banach spaces, which relax the conditions appearing in the usual studies. The approach is based on the bound required for the second derivative of the operator involved. An application to a nonlinear integral equation is presented. 相似文献
32.
33.
T. Temesvári C. De Dominicis I.R. Pimentel 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,25(3):361-372
Symmetry considerations and a direct, Hubbard-Stratonovich type, derivation are used to construct a replica field-theory relevant
to the study of the spin glass transition of short range models in a magnetic field. A mean-field treatment reveals that two
different types of transitions exist, whenever the replica number n is kept larger than zero. The Sherrington-Kirkpatrick critical point in zero magnetic field between the paramagnet and replica
magnet (a replica symmetric phase with a nonzero spin glass order parameter) separates from the de Almeida-Thouless line,
along which replica symmetry breaking occurs. We argue that for studying the de Almeida-Thouless transition around the upper
critical dimension d = 6, it is necessary to use the generic cubic model with all the three bare masses and eight cubic couplings. The critical
role n may play is also emphasized. To make perturbative calculations feasible, a new representation of the cubic interaction is
introduced. To illustrate the method, we compute the masses in one-loop order. Some technical details and a list of vertex
rules are presented to help future renormalisation-group calculations.
Received 9 October 2001 相似文献
34.
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
35.
We analyze diffusion from a periodic array of hemispherical droplets through a membrane. We find that the multiple sources do not interact strongly, even when the droplets are closely spaced, so that the flux through the membrane appears nearly additive. 相似文献
36.
The annealing algorithm (Ref. 1) is modified to allow for noisy or imprecise measurements of the energy cost function. This is important when the energy cannot be measured exactly or when it is computationally expensive to do so. Under suitable conditions on the noise/imprecision, it is shown that the modified algorithm exhibits the same convergence in probability to the globally minimum energy states as the annealing algorithm (Ref. 2). Since the annealing algorithm will typically enter and exit the minimum energy states infinitely often with probability one, the minimum energy state visited by the annealing algorithm is usually tracked. The effect of using noisy or imprecise energy measurements on tracking the minimum energy state visited by the modified algorithms is examined.The research reported here has been supported under Contracts AFOSR-85-0227, DAAG-29-84-K-0005, and DAAL-03-86-K-0171 and a Purdue Research Initiation Grant. 相似文献
37.
38.
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
39.
给出2005年全国部分高校研究生数学建模竞赛D题的研究背景,对参赛论文作了简要评注,并提供了一种参考解答. 相似文献
40.
We obtain upper bounds for the tail distribution of the first nonnegative sum of a random walk and for the moments of the overshoot over an arbitrary nonnegative level if the expectation of jumps is positive and close to zero. In addition, we find an estimate for the expectation of the first ladder epoch. 相似文献