全文获取类型
收费全文 | 43002篇 |
免费 | 2759篇 |
国内免费 | 1790篇 |
专业分类
化学 | 30590篇 |
晶体学 | 364篇 |
力学 | 1403篇 |
综合类 | 94篇 |
数学 | 6747篇 |
物理学 | 8353篇 |
出版年
2023年 | 340篇 |
2022年 | 593篇 |
2021年 | 776篇 |
2020年 | 888篇 |
2019年 | 924篇 |
2018年 | 732篇 |
2017年 | 685篇 |
2016年 | 1359篇 |
2015年 | 1340篇 |
2014年 | 1428篇 |
2013年 | 2497篇 |
2012年 | 2749篇 |
2011年 | 3235篇 |
2010年 | 1856篇 |
2009年 | 1684篇 |
2008年 | 2722篇 |
2007年 | 2600篇 |
2006年 | 2514篇 |
2005年 | 2347篇 |
2004年 | 2023篇 |
2003年 | 1783篇 |
2002年 | 1792篇 |
2001年 | 825篇 |
2000年 | 653篇 |
1999年 | 579篇 |
1998年 | 523篇 |
1997年 | 489篇 |
1996年 | 604篇 |
1995年 | 450篇 |
1994年 | 382篇 |
1993年 | 337篇 |
1992年 | 322篇 |
1991年 | 295篇 |
1990年 | 238篇 |
1989年 | 230篇 |
1988年 | 253篇 |
1987年 | 214篇 |
1985年 | 355篇 |
1984年 | 353篇 |
1983年 | 253篇 |
1982年 | 317篇 |
1981年 | 336篇 |
1980年 | 304篇 |
1979年 | 288篇 |
1978年 | 261篇 |
1977年 | 228篇 |
1976年 | 209篇 |
1975年 | 210篇 |
1974年 | 214篇 |
1973年 | 211篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
121.
David Fryberger 《Foundations of Physics Letters》1990,3(4):379-386
Issues raised by W. A. Rodrigues, Jr. are discussed.1. This is not a new result; see,e.g., Rohrlich.(3)
2. A typographical error in Eq. (77) is corrected here: The productj A in the right-hand parentheses was erroneously transcribed in Ref. (2) as
A.3. I define electromagnetic fieldF = A to be that generated by electric charges and the magnetoelectric fieldG = M to be that generated by magnetic monopoles:F F +5
G.
4. Rodrigues, on the other hand, takes the position that the importance of the Lagrangian formulation should be downgraded if not discarded altogether: ... it is redundant to look for Lagrangians.(1)
5. In fact, he reformulates it using the language of differential forms.6. It is interesting to observe that this bilinear form has the additional virtue of being appropriate for dealing with the monopolecharge parity question, which was pointed out long ago.(14)
7. In fact, even mathematics looks to Nature for its authority.(16) There is evidence that Rodrigues does not understand this concept.(17) 相似文献
122.
Summary We prove the fundamental lemma for spherical functions with respect to the natural (induction) lifting fromPGL(2) toPGL(3) which appears as the unstable counterpart of the stable symmetric-square lifting fromSL(2) toPGL(3) (see [IV] for an introduction to this project, and [VI] for the final results). Thus spherical functions onPGL(2) andPGL(3) which correspond to each other by satisfying an elementary representation theoretic relation are shown to have matching orbital integrals. The proof of this local statement is based on an application of the global trace formula.Partially supported by NSF grants 相似文献
123.
David G. Kirkpatrick 《Discrete and Computational Geometry》1988,3(1):267-280
A planar subdivision is the partition of the plane induced by an embedded planar graph. A representation of such a subdivision isordered if, for each vertexv of the associated graphG, the (say) clockwise sequence of edges in the embedding ofG incident withv appears explicitly.The worst-case complexity of establishing order in a planar subdivision, i.e., converting an unordered representation into an ordered one, is shown to be (n + log (G)), wheren is the size (number of vertices) of the underlying graphG and (G) is (essentially) the number of topologically distinct embeddings ofG in the plane.This work was supported by the National Science and Engineering Research Council of Canada under Grant A3583. A preliminary version of this paper appeared in theProceedings of the Third Annual ACM Symposium on Computational Geometry. 相似文献
124.
125.
126.
Gabriel M. Rebeiz Curtis C. Ling David B. Rutledge 《International Journal of Infrared and Millimeter Waves》1989,10(8):931-936
An accurate monolithic power meter has been developed for millimeter-wave applications. The detector is a large-area Bismuth bolometer, integrated on a fused-Quartz substrate. It simply measures the temperature change caused by the absorption of millimeter-wave radiation. The power meter is simple to fabricate, inexpensive, and can be easily calibrated using a low-frequency network. The measured responsivity for a 50 bolometer, with an area of 1×1cm, at a bias of 1V. and a video modulation of 100Hz, is 1mV/W. The noise spectrum exhibits a 1/f rolloff till 1KHz, and is limited by the Johnson noise for higher frequencies. The NEP of the detector is 3WHz–1/2 at a video modulation of 1KHz. It is possible to decrease the current NEP by fabricating bolometers with higher responsivities. Possible application areas are absolute power calibration and localized power density measurements at millimeter and submillimeter wavelengths. 相似文献
127.
128.
Heptakis(2,6-di-O-methyl)-β-cyclodextrin interacts with 5,15-diphenylporphine to produce a 2:1 complex in dimethyl sulfoxide. This complex possesses a hydrophobic groove that circumscribes the metal binding site of the porphyrin moiety. 相似文献
129.
130.
A new phase selective hydrocarbon soluble polymer support is described. 相似文献