全文获取类型
收费全文 | 129584篇 |
免费 | 8970篇 |
国内免费 | 6230篇 |
专业分类
化学 | 61039篇 |
晶体学 | 1417篇 |
力学 | 9601篇 |
综合类 | 377篇 |
数学 | 37498篇 |
物理学 | 34852篇 |
出版年
2024年 | 186篇 |
2023年 | 1142篇 |
2022年 | 2114篇 |
2021年 | 2261篇 |
2020年 | 2312篇 |
2019年 | 2204篇 |
2018年 | 11862篇 |
2017年 | 11666篇 |
2016年 | 8470篇 |
2015年 | 3521篇 |
2014年 | 3451篇 |
2013年 | 4378篇 |
2012年 | 8582篇 |
2011年 | 15060篇 |
2010年 | 8850篇 |
2009年 | 9020篇 |
2008年 | 9811篇 |
2007年 | 11554篇 |
2006年 | 2896篇 |
2005年 | 3582篇 |
2004年 | 3261篇 |
2003年 | 3343篇 |
2002年 | 2282篇 |
2001年 | 1268篇 |
2000年 | 1197篇 |
1999年 | 1214篇 |
1998年 | 1056篇 |
1997年 | 952篇 |
1996年 | 992篇 |
1995年 | 845篇 |
1994年 | 688篇 |
1993年 | 615篇 |
1992年 | 484篇 |
1991年 | 455篇 |
1990年 | 381篇 |
1989年 | 299篇 |
1988年 | 237篇 |
1987年 | 220篇 |
1986年 | 217篇 |
1985年 | 187篇 |
1984年 | 129篇 |
1983年 | 130篇 |
1982年 | 97篇 |
1981年 | 78篇 |
1980年 | 75篇 |
1979年 | 62篇 |
1978年 | 42篇 |
1973年 | 41篇 |
1914年 | 45篇 |
1909年 | 41篇 |
排序方式: 共有10000条查询结果,搜索用时 22 毫秒
131.
关于多线性振荡奇异积分在加权Hardy-型空间上的一致估计 总被引:1,自引:0,他引:1
本文对一类具有光滑位相函数的多线性振荡奇异积分算子建立了一致的加权(H^1(R^n),L^1(R^n))估计及一致的加权(HKp(R^n),Kp(R^n)估计。 相似文献
132.
133.
134.
Elizabeth Wulcan 《Arkiv f?r Matematik》2007,45(1):157-178
With a given holomorphic section of a Hermitian vector bundle, one can associate a residue current by means of Cauchy–Fantappiè–Leray
type formulas. In this paper we define products of such residue currents. We prove that, in the case of a complete intersection,
the product of the residue currents of a tuple of sections coincides with the residue current of the direct sum of the sections. 相似文献
135.
Liang-gen Hu 《应用数学学报(英文版)》2007,23(2):281-288
In this paper,we will establish several strong convergence theorems for the approximation ofcommon fixed points of r-strictly asymptotically pseudocontractive mappings in uniformly convex Banachspaces using the modiied implicit iteration sequence with errors,and prove the necessary and sufficient conditionsfor the convergence of the sequence.Our results generalize,extend and improve the recent work,in thistopic. 相似文献
136.
Daniel Maerten 《Annals of Global Analysis and Geometry》2007,32(4):391-414
We prove a Penrose-like inequality for the mass of a large class of constant mean curvature (CMC) asymptotically flat n-dimensional spin manifolds which satisfy the dominant energy condition and have a future converging, or past converging compact
and connected boundary of non-positive mean curvature and of positive Yamabe invariant. We prove that for every n ≥ 3 the mass is bounded from below by an expression involving the norm of the linear momentum, the volume of the boundary,
dimensionless geometric constants and some normalized Sobolev ratio. 相似文献
137.
In cricket, a rain-affected pitch can make batting more difficult than normal. Several other conditions such as poor light or an initially lively pitch, may also result in difficulties for the batsmen. In this note, we refer to all of them as ‘sticky wickets’. On sticky wickets, lower order batsmen are often sent into ‘hold the fort’ until conditions improve. In this paper, a stochastic dynamic programming model is used to examine the appropriateness of this policy. The model suggests that the tactic is often optimal when the sticky wicket persists until the end of the day's play, but not often when the sticky wicket is transitory. In some circumstances, it is worthwhile, on a normal wicket near the end of the day, to send in a lower order batsman to hold the fort (a night watchman): when the wicket is sticky, this tactic is even more worthwhile. 相似文献
138.
139.
Yu You George W. Kattawar Ping Yang Yong X. Hu Bryan A. Baum 《Journal of Quantitative Spectroscopy & Radiative Transfer》2006,100(1-3):470-482
Measurements from depolarized lidars provide a promising method to retrieve both cloud and aerosol properties and a versatile complement to passive satellite-based sensors. For lidar observations of clouds and aerosols, multiple scattering plays an important role in the scattering process. Monte Carlo simulations are carried out to investigate the sensitivity of lidar backscattering depolarization to cloud and aerosol properties. Lidar parameters are chosen to be similar to those of the upcoming space-based CALIPSO lidar. Cases are considered that consist of a single cloud or aerosol layer, as well as a case in which cirrus clouds overlay different types of aerosols. It is demonstrated that besides thermodynamic cloud phase, the depolarized lidar signal may provide additional information on ice or aerosol particle shapes. However, our results show little sensitivity to ice or aerosol particle sizes. Additionally, for the case of multiple but overlapping layers involving both clouds and aerosols, the depolarized lidar contains information that can help identify the particle properties of each layer. 相似文献
140.
In this paper, nonconvex multiobjective optimization problems are studied. New characterizations of a properly efficient solution in the sense of Geoffrion's are established in terms of the stability of one scalar optimization problem and the existence of an exact penalty function of a scalar constrained program, respectively. One of the characterizations is applied to derive necessary conditions for a properly efficient control-parameter pair of a nonconvex multiobjective discrete optimal control problem with linear constraints. 相似文献