全文获取类型
收费全文 | 662篇 |
免费 | 9篇 |
国内免费 | 1篇 |
专业分类
化学 | 277篇 |
晶体学 | 6篇 |
力学 | 39篇 |
数学 | 153篇 |
物理学 | 197篇 |
出版年
2021年 | 6篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 3篇 |
2016年 | 3篇 |
2015年 | 11篇 |
2014年 | 7篇 |
2013年 | 25篇 |
2012年 | 22篇 |
2011年 | 29篇 |
2010年 | 9篇 |
2009年 | 15篇 |
2008年 | 28篇 |
2007年 | 32篇 |
2006年 | 33篇 |
2005年 | 34篇 |
2004年 | 23篇 |
2003年 | 15篇 |
2002年 | 10篇 |
2001年 | 17篇 |
2000年 | 16篇 |
1999年 | 15篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 13篇 |
1995年 | 14篇 |
1994年 | 24篇 |
1993年 | 26篇 |
1992年 | 18篇 |
1991年 | 10篇 |
1990年 | 6篇 |
1989年 | 8篇 |
1988年 | 10篇 |
1987年 | 9篇 |
1986年 | 8篇 |
1985年 | 12篇 |
1984年 | 7篇 |
1983年 | 11篇 |
1982年 | 9篇 |
1981年 | 7篇 |
1980年 | 6篇 |
1979年 | 10篇 |
1978年 | 6篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1975年 | 11篇 |
1974年 | 6篇 |
1973年 | 8篇 |
1968年 | 5篇 |
1907年 | 4篇 |
排序方式: 共有672条查询结果,搜索用时 15 毫秒
31.
Stuart Lang Neil Muir Franziska Schönebeck Andrew H. Payne 《Tetrahedron letters》2005,46(23):4027-4030
The phosphorus based radical precursors N-ethylpiperidine hypophosphite (EPHP) and diethylphosphine oxide (DEPO) are efficient reagents for carrying out the formation of seven- and eight-membered rings. Esters and amides were successfully converted into the corresponding eight-membered lactones and seven- and eight-membered lactams in good to excellent yields. 相似文献
32.
L. E. Payne G. A. Philippin 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1991,42(6):864-873
Summary In this paper we study various overdetermined problems involving harmonic functions. In particular, we show that if the second eigenfunctionu
2 of the Stekloff eigenvalue problem in a bounded simply connected plane domain has a constant value of u
2 on , then is a disk
Résumé Cet article est consacré à l'étude de certains problèmes surdéterminés pour des fonctions harmoniques. En particulier, nous montrons que si le gradient de la seconde fonction propre du problème de Stekloff défini dans un domaine borné, simplement connexe du plan, a son module constant sur la frontière , alors est nécessairement un disque.相似文献
33.
34.
35.
36.
Louis P. Lee Daniel J. Cole Mike C. Payne Chris‐Kriton Skylaris 《Journal of computational chemistry》2013,34(6):429-444
First principles electronic structure calculations are typically performed in terms of molecular orbitals (or bands), providing a straightforward theoretical avenue for approximations of increasing sophistication, but do not usually provide any qualitative chemical information about the system. We can derive such information via post‐processing using natural bond orbital (NBO) analysis, which produces a chemical picture of bonding in terms of localized Lewis‐type bond and lone pair orbitals that we can use to understand molecular structure and interactions. We present NBO analysis of large‐scale calculations with the ONETEP linear‐scaling density functional theory package, which we have interfaced with the NBO 5 analysis program. In ONETEP calculations involving thousands of atoms, one is typically interested in particular regions of a nanosystem whilst accounting for long‐range electronic effects from the entire system. We show that by transforming the Non‐orthogonal Generalized Wannier Functions of ONETEP to natural atomic orbitals, NBO analysis can be performed within a localized region in such a way that ensures the results are identical to an analysis on the full system. We demonstrate the capabilities of this approach by performing illustrative studies of large proteins—namely, investigating changes in charge transfer between the heme group of myoglobin and its ligands with increasing system size and between a protein and its explicit solvent, estimating the contribution of electronic delocalization to the stabilization of hydrogen bonds in the binding pocket of a drug‐receptor complex, and observing, in situ, the n → π* hyperconjugative interactions between carbonyl groups that stabilize protein backbones. © 2012 Wiley Periodicals, Inc. 相似文献
37.
Acceleration and mitigation of carrier‐induced degradation in p‐type multi‐crystalline silicon 下载免费PDF全文
D. N. R. Payne C. E. Chan B. J. Hallam B. Hoex M. D. Abbott S. R. Wenham D. M. Bagnall 《固体物理学:研究快报》2016,10(3):237-241
Recently, a new carrier‐induced defect has been reported in multi‐crystalline silicon (mc‐Si), and has been shown to be particularly detrimental to the performance of passivated emitter and rear contact (PERC) cells. Under normal conditions, this defect can take years to fully form. This Letter reports on the accelerated formation and subsequent passivation of this carrier‐induced defect through the use of high illumination intensity and elevated temperatures resulting in passivation within minutes. The process was tested on industrial mc‐Si PERC solar cells, where degradation after a 100 hour stability test was suppressed to only 0.1% absolute compared to 2.1% for non‐treated cells. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
38.
39.
Luminescent quantum dots (QDs) are colloidal semiconductor nanocrystals consisting of an inorganic core covered by a molecular layer of organic surfactants. Although QDs have been known for more than thirty years, they are still attracting the interest of researchers because of their unique size-tunable optical and electrical properties arising from quantum confinement. Moreover, the controlled decoration of the QD surface with suitable molecular species enables the rational design of inorganic-organic multicomponent architectures that can show a vast array of functionalities. This minireview highlights the recent progress in the use of surface-modified QDs – in particular, those based on cadmium chalcogenides – as supramolecular platforms for light-related applications such as optical sensing, triplet photosensitization, photocatalysis and phototherapy. 相似文献
40.
We report room-temperature mid-IR laser operation in a new low-phonon-frequency nonhygroscopic host crystal, calcium thiogallate (CaGa(2)S(4)) . Laser action at 4.314.38 mum on the Dy(3+)H(11/2)(6)?H(13/2)(6) transition occurred with a maximum slope efficiency of 1.6%. 相似文献