全文获取类型
收费全文 | 24908篇 |
免费 | 954篇 |
国内免费 | 45篇 |
专业分类
化学 | 16459篇 |
晶体学 | 174篇 |
力学 | 466篇 |
综合类 | 1篇 |
数学 | 4364篇 |
物理学 | 4443篇 |
出版年
2023年 | 163篇 |
2022年 | 174篇 |
2021年 | 300篇 |
2020年 | 404篇 |
2019年 | 398篇 |
2018年 | 534篇 |
2017年 | 460篇 |
2016年 | 969篇 |
2015年 | 751篇 |
2014年 | 800篇 |
2013年 | 1620篇 |
2012年 | 1631篇 |
2011年 | 1665篇 |
2010年 | 997篇 |
2009年 | 924篇 |
2008年 | 1450篇 |
2007年 | 1461篇 |
2006年 | 1321篇 |
2005年 | 1185篇 |
2004年 | 1060篇 |
2003年 | 838篇 |
2002年 | 726篇 |
2001年 | 529篇 |
2000年 | 474篇 |
1999年 | 355篇 |
1998年 | 246篇 |
1997年 | 230篇 |
1996年 | 307篇 |
1995年 | 221篇 |
1994年 | 246篇 |
1993年 | 207篇 |
1992年 | 202篇 |
1991年 | 185篇 |
1990年 | 183篇 |
1989年 | 155篇 |
1988年 | 149篇 |
1987年 | 136篇 |
1986年 | 143篇 |
1985年 | 201篇 |
1984年 | 202篇 |
1983年 | 128篇 |
1982年 | 137篇 |
1981年 | 144篇 |
1980年 | 141篇 |
1979年 | 103篇 |
1978年 | 105篇 |
1977年 | 109篇 |
1976年 | 87篇 |
1975年 | 92篇 |
1973年 | 76篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
The big trip is a cosmological process thought to occur in the future by which the entire universe would be engulfed inside a gigantic wormhole and might travel through it along space and time. In this Letter we discuss different arguments that have been raised against the viability of that process, reaching the conclusions that the process can actually occur by accretion of phantom energy onto the wormholes and that it is stable and might occur in the global context of a multiverse model. We finally argue that the big trip does not contradict any holographic bounds on entropy and information. 相似文献
62.
63.
64.
Georg Pólya 《Mathematische Zeitschrift》1923,18(1):96-108
Ohne Zusammenfassung 相似文献
65.
Pedro Ontaneda 《Geometriae Dedicata》2004,104(1):25-35
We study the following question: does a compact nonpositively curved space have a totally geodesic core? 相似文献
66.
In this paper a new multidimensional extension of the recently developed one-dimensional enclosure method called kite is given for interval global optimization. A more sophisticated version of the pruning technique based on the kite method is introduced. By the new componentwise approach all the one-dimensional theoretical results and procedures can be used in the higher-dimensional case. The possibilities in the implementation of the new algorithm together with numerical results on 40 standard test problems are presented. 相似文献
67.
68.
A classification of homogeneous quaternionic Kähler structures by real tensors is given and related to Fino's representation theoretic decomposition. A relationship between the modules whose dimension grows linearly and quaternionic hyperbolic space is found. To cite this article: M. Castrillón López et al., C. R. Acad. Sci. Paris, Ser. I 338 (2004). 相似文献
69.
A. López-Ortega 《General Relativity and Gravitation》2004,36(6):1299-1319
We show that the Dirac equation is separable in the circularly symmetric metric in three dimensions and when the background spacetime is de Sitter we find exact solutions to the radial equations. Using these results we show that the de Sitter horizon has a cross section equal to zero for the massless Dirac field, as in the case of the scalar field. Also, using the improved brick wall model we calculate the fermionic entropy associated with the de Sitter horizon and we compare it with some results previously published. 相似文献
70.
Z. Kassai V. Koprda K. Bauerová M. Harangozó P. Bendová A. Bujnová A. Kassai 《Journal of Radioanalytical and Nuclear Chemistry》2003,258(3):669-672
The composition and the permeation properties of the skin are dependent on age. In the animal models for permation studies, age affects the mechanical as well as the permeation properties significantly. The time dependence of permeation of 147Pm3+ from aqueous solution was established by the animal skin model and the age dependence of promethium permeation through the skin was examined. The aim was to find the optimum rat skin age model for radionuclide permeation studies and to assess the relative importance of the main permeation pathways: transepidermal and transfollicular permeation. The skin from 5-day-old rats (5DR) was found to represent the optimum animal model to study transepidermal permeation of ions. The skin from 9-day-old rats (9DR) was selected to study transfollicular permeation of ions. Comparison of the permeated amounts of promethium through the skin without hairs (3 DR to 6 DR) and with hairs (7DR to 12DR) showed that the additional permation mode via follicles significantly contributed to the permeation rate and extent. 相似文献