全文获取类型
收费全文 | 173007篇 |
免费 | 16890篇 |
国内免费 | 12076篇 |
专业分类
化学 | 92543篇 |
晶体学 | 1805篇 |
力学 | 11897篇 |
综合类 | 666篇 |
数学 | 43429篇 |
物理学 | 51633篇 |
出版年
2024年 | 116篇 |
2023年 | 1998篇 |
2022年 | 2291篇 |
2021年 | 3390篇 |
2020年 | 4110篇 |
2019年 | 3868篇 |
2018年 | 13087篇 |
2017年 | 12640篇 |
2016年 | 10389篇 |
2015年 | 5452篇 |
2014年 | 6062篇 |
2013年 | 7822篇 |
2012年 | 12656篇 |
2011年 | 19325篇 |
2010年 | 11920篇 |
2009年 | 11961篇 |
2008年 | 12900篇 |
2007年 | 14254篇 |
2006年 | 5771篇 |
2005年 | 5885篇 |
2004年 | 5093篇 |
2003年 | 4817篇 |
2002年 | 3622篇 |
2001年 | 2455篇 |
2000年 | 2227篇 |
1999年 | 2200篇 |
1998年 | 1922篇 |
1997年 | 1688篇 |
1996年 | 1681篇 |
1995年 | 1460篇 |
1994年 | 1304篇 |
1993年 | 1081篇 |
1992年 | 944篇 |
1991年 | 834篇 |
1990年 | 694篇 |
1989年 | 556篇 |
1988年 | 430篇 |
1987年 | 391篇 |
1986年 | 387篇 |
1985年 | 307篇 |
1984年 | 229篇 |
1983年 | 188篇 |
1982年 | 166篇 |
1981年 | 116篇 |
1980年 | 105篇 |
1979年 | 68篇 |
1978年 | 56篇 |
1973年 | 42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 15 毫秒
971.
Victor V. Dodonov Margarita A. Man’ko Vladimir I. Man’ko Apostol Vourdas 《Journal of Russian Laser Research》2007,28(5):404-428
A brief review of the history of ten workshops/conferences on “Squeezed States and Uncertainty Relations” and main achievements
in the related fields of quantum physics for the period from 1991 to 2007 are presented. 相似文献
972.
973.
974.
A group of machines for processing a set of jobs in a manufacturing system is often located in a serial line. An efficient strategy for locating these machines such that the total travel distance or the cost of transporting the jobs is minimized is desired. In this research, the assumption of a linear line with equally spaced machine location is relaxed. This research addressed problems of locating unique machines. It is found that the machine distances possess unique properties in this type of a problem. Utilizing these properties, heuristic strategies are proposed to obtain efficient solution where optimal methods are expected to be computationally prohibitive. A lower bound for the optimum solution is also proposed. Results are encouraging. 相似文献
975.
Martin I. Karakhanyan 《Journal of Contemporary Mathematical Analysis (Armenian Academy of Sciences)》2007,42(3):146-150
The paper proves some general facts on commutators that refer to Fuglede-Putnam classical theorem in the spectral theory of not necessarily selfadjoint operators. 相似文献
976.
Stimulated Raman adiabatic passage (STIRAP) has been successfully extended to multilevel system. During the STIRAP process, the intermediate levels have notable population which is detrimental if these levels could decay to other levels through spontaneous emission. This paper proposes a novel method to reduce the intermediate level population during the STIRAP process. A complete population transfer can be achieved in this modified STIRAP even if the intermediate level decays to other levels. 相似文献
977.
Those who have worked in the Royal Institution of Great Britain have, since its foundation in 1799, made significant contributions
to scientific knowledge, to its practical application, and to its communication to a wide variety of audiences. Such work
cannot be carried out in an architectural vacuum, and in this paper we examine how the buildings of the Royal Institution,
20 and 21 Albemarle Street in central London, have shaped the work undertaken within its walls and how, on a number of occasions,
the buildings have been reconfigured to take account of the evolving needs of scientific research and communication.
This paper is based on the Conservation Plan of the Royal Institution that we wrote during 2003. The Conservation Plan did
not examine the land owned by the Royal Institution to the north (i.e., 22 and 23 Albemarle Street; for this area see Richard Garnier, “Grafton Street, Mayfair,” Georgian Group Journal 13 (2003), 210–272), but it did discuss 18 and 19 Albemarle Street. In this paper we concentrate on the core Royal Institution
buildings at 20 and 21 Albemarle Street. Other studies of the relationship of architecture,space, and science include Crosbie
Smith and Jon Agar, ed., Making Space for Science: Territorial Themes in the Shaping of Knowledge (Basingstoke: Macmillan, 1997); Peter Galison and Emily Thompson, ed., The Architecture of Science (Cambridge, Mass.: MIT Press, 1999); and Sophie Forgan,“The architecture of science and the idea of a university,” Studies in History and Philosophy of Science 20 (1989), 405–434.
Frank A.J.L. James is Professor of the History of Science at the Royal Institution; he has written widely on the history of
nineteenth-century science in its social and cultural contexts and is editor of the Correspondence of Michael Faraday. He is President of the British Society for the History of Science. Anthony Peers is an Associate of Rodney Melville and
Partners where he works in the field of building conservation as an architectural historian. He is a Council member of the
Ancient Monument Society. 相似文献
978.
François Loiseau Jean-Mary Simone David Carcache Pavel Bobal Reinhard Neier 《Monatshefte für Chemie / Chemical Monthly》2007,138(2):121-129
Summary. Free radical couplings from furan, as cheap starting material, were studied in view of developing a rapid strategy en route to the synthesis of derivatives of nonactin. The chain containing the alcohol function was introduced in one or two steps
in 86% yield. For the introduction of the second chain with the ester function two different coupling methods were tested.
Starting from the advanced intermediates obtained nonactin derivatives can be prepared by catalytic hydrogenation of the furan
ring. 相似文献
979.
Katharina Habermann Lutz Habermann Paul Rosenthal 《Calculus of Variations and Partial Differential Equations》2007,30(2):137-152
A Yang–Mills theory in a purely symplectic framework is developed. The corresponding Euler–Lagrange equations are derived
and first integrals are given. We relate the results to the work of Bourgeois and Cahen on preferred symplectic connections. 相似文献
980.
David Worthington 《The Journal of the Operational Research Society》1991,42(10):833-843
This paper describes work carried out with hospital consultants in Lancaster District Health Authority to develop and use computerized waiting list management models. The ‘what if?’ models produced have been found to be a very useful tool in the constructive debate about problems faced by consultants and managers, and of the options available to them. 相似文献