全文获取类型
收费全文 | 15260篇 |
免费 | 933篇 |
国内免费 | 431篇 |
专业分类
化学 | 9658篇 |
晶体学 | 121篇 |
力学 | 552篇 |
综合类 | 40篇 |
数学 | 2475篇 |
物理学 | 3778篇 |
出版年
2023年 | 161篇 |
2022年 | 311篇 |
2021年 | 440篇 |
2020年 | 479篇 |
2019年 | 412篇 |
2018年 | 356篇 |
2017年 | 316篇 |
2016年 | 611篇 |
2015年 | 559篇 |
2014年 | 589篇 |
2013年 | 940篇 |
2012年 | 1075篇 |
2011年 | 1241篇 |
2010年 | 719篇 |
2009年 | 668篇 |
2008年 | 955篇 |
2007年 | 861篇 |
2006年 | 789篇 |
2005年 | 726篇 |
2004年 | 592篇 |
2003年 | 483篇 |
2002年 | 447篇 |
2001年 | 262篇 |
2000年 | 191篇 |
1999年 | 213篇 |
1998年 | 144篇 |
1997年 | 161篇 |
1996年 | 149篇 |
1995年 | 142篇 |
1994年 | 143篇 |
1993年 | 129篇 |
1992年 | 124篇 |
1991年 | 101篇 |
1990年 | 96篇 |
1989年 | 79篇 |
1988年 | 63篇 |
1987年 | 64篇 |
1986年 | 58篇 |
1985年 | 85篇 |
1984年 | 87篇 |
1983年 | 37篇 |
1982年 | 75篇 |
1981年 | 45篇 |
1980年 | 46篇 |
1979年 | 72篇 |
1978年 | 53篇 |
1977年 | 36篇 |
1976年 | 36篇 |
1974年 | 36篇 |
1973年 | 28篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
Alberto Mariani Simone Bidali Stefano Fiori Marco Sangermano Giulio Malucelli Roberta Bongiovanni Aldo Priola 《Journal of polymer science. Part A, Polymer chemistry》2004,42(9):2066-2072
By combining frontal polymerization and radical‐induced cationic polymerization, it was possible to cure thick samples of an epoxy monomer bleached by UV light. The effect of the relative amounts of cationic photoinitiator and radical initiator was thoroughly investigated and was related to the front's velocity and its maximum temperature. The materials obtained were characterized by quantitative conversion also in the deeper layers, not reached by UV light. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2066–2072, 2004 相似文献
32.
33.
Siaw-Lynn Ng 《Order》2004,21(1):1-5
We present a characterisation of posets of size n with linear discrepancy n − 2. These are the posets that are “furthest” from a linear order without being an antichain.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
34.
We will prove a result concerning the inclusion of non-trivial invariant ideals inside non-trivial ideals of a twisted crossed
product. We will also give results concerning the primeness and simplicity of crossed products of twisted actions of locally
compact groups on -algebras.
Received: 25 January 2002; in final form: 22 May 2002/Published online: 2 December 2002
This work is partially supported by Hong Kong RGC Direct Grant. 相似文献
35.
Some nickel, copper, and silver salts or complexes are efficient catalysts for the oxidation of benzylic ethers with oxygen in 1,2-dimethoxyethane. Salts of the weakly coordinating anion trifluoroacetate are particularly efficient, approaching (and, in some cases, improving) the yields obtained with cobalt(II) chloride, the best catalyst so far reported. 相似文献
36.
Marco Sangermano Mehmet Atilla Tasdelen Yusuf Yagci 《Journal of polymer science. Part A, Polymer chemistry》2007,45(21):4914-4920
Photoinitiated cationic polymerization of mono‐ and bifunctional epoxy monomers, namely cyclohexeneoxide (CHO), 4‐epoxycyclohexylmethyl‐3′,4′‐epoxycyclohexanecarboxylate (EEC), respectively by using sulphonium salts in the presence of hydroxylbutyl vinyl ether (HBVE) was studied. The real‐time FTIR spectroscopic, gel content determination, and thermal characterization studies revealed that both hydroxyl and vinyl ether functionalities of HBVE take part in the polymerization. During the polymerization, HBVE has the ability to react via both active chain end (ACE) and activated monomer mechanisms through its hydroxyl and vinyl ether functionalities, respectively. Thus, more efficient curing was observed with the addition of HBVE into EEC‐containing formulations. It was also demonstrated that HBVE is effective in facilitating the photoinduced crosslinking of monofunctional epoxy monomer, CHO in the absence of a conventional crosslinker. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4914–4920, 2007 相似文献
37.
A. Di Maio A. Rocco P. Ferraro M. De Rosa P. De Natale S. De Nicola A. Finizio G. Pierattini G. Coppola M. Iodice V. Striano 《Optics and Lasers in Engineering》2007,45(3):385
In view of the growing interest for non-destructive tests of materials, geodynamical monitoring and in general remote sensing, there is a great effort to bring practical optical sensors from research labs to industrial and environmental applications. In this paper, we employ digital holographic technique as an efficient tool for evaluating the strain measurement capability of fiber Bragg gratings (FBG). A cantilever beam has been employed as a test structure under loading test. The strain measurements results obtained by fiber-based sensors have been compared to those obtained by using full-field digital holographic technique and point-wise strain gauge sensors glued on the same cantilever beam. A simple theoretical model is also presented to interpret and compare the experimental results coming from different techniques. 相似文献
38.
We study the real valued functions having a primitive with respect to the oscillation or a primitive with respect to the oscillation
up to anegligible set.
Supported by MURST of Italy. 相似文献
Supported by MURST of Italy. 相似文献
39.
Marco Lehmann-Waffenschmidt 《Central European Journal of Operations Research》2006,14(3):289-298
It is routine to demonstrate in the exchange economy framework that small changes of individual preferences and endowments always result in small changes of the derived excess demand functions as one should expect. Though being as desirable for reasons of the consistency of the whole approach, however, a precise proof of the converse direction so far is still open to question. The present paper shows that it is actually true. We use a decomposition method for aggregate excess demand functions developed by Mas-Colell which is derived from the well-known decomposition method developed by Sonnenschein and perfected by Debreu and Mantel. Our result fills in a notorious gap in the line of economic justification usually given for this decomposition, or disaggregation, method in that comparative static analysis would be restricted if the decomposition of excess demand functions would not be continuous. 相似文献
40.
B. Savo P. Romano A. Nigro R. Di Leo 《Physica C: Superconductivity and its Applications》2002,370(4):275-280
The flat voltage noise component of current biased, high-transparency Nb/AlOx/Nb superconducting tunnel junctions has been investigated at frequencies up to 70 kHz. Several aspects of the analyzed phenomena suggest the presence of current noise effects induced by the discreteness of the charge carriers. At subgap voltages, where excess currents occur, a behavior coherent with a multiple Andreev reflection-assisted transport through the tunnel barrier has been found. However, the measured charge values exceed any theoretical prediction. 相似文献