全文获取类型
收费全文 | 3969篇 |
免费 | 144篇 |
国内免费 | 2篇 |
专业分类
化学 | 2644篇 |
晶体学 | 9篇 |
力学 | 98篇 |
数学 | 556篇 |
物理学 | 808篇 |
出版年
2023年 | 28篇 |
2022年 | 21篇 |
2021年 | 30篇 |
2020年 | 51篇 |
2019年 | 34篇 |
2018年 | 67篇 |
2017年 | 36篇 |
2016年 | 93篇 |
2015年 | 101篇 |
2014年 | 107篇 |
2013年 | 200篇 |
2012年 | 276篇 |
2011年 | 289篇 |
2010年 | 145篇 |
2009年 | 124篇 |
2008年 | 198篇 |
2007年 | 228篇 |
2006年 | 193篇 |
2005年 | 178篇 |
2004年 | 158篇 |
2003年 | 119篇 |
2002年 | 118篇 |
2001年 | 62篇 |
2000年 | 32篇 |
1999年 | 25篇 |
1998年 | 23篇 |
1997年 | 23篇 |
1996年 | 20篇 |
1995年 | 20篇 |
1994年 | 20篇 |
1993年 | 19篇 |
1988年 | 16篇 |
1983年 | 18篇 |
1982年 | 16篇 |
1981年 | 23篇 |
1980年 | 15篇 |
1977年 | 15篇 |
1937年 | 20篇 |
1936年 | 16篇 |
1935年 | 17篇 |
1934年 | 26篇 |
1933年 | 24篇 |
1932年 | 29篇 |
1931年 | 18篇 |
1930年 | 24篇 |
1929年 | 24篇 |
1928年 | 20篇 |
1927年 | 28篇 |
1926年 | 15篇 |
1924年 | 20篇 |
排序方式: 共有4115条查询结果,搜索用时 15 毫秒
81.
The synthesis of a new series of stable and soluble EDOT oligomers end-capped with n-hexyl groups is described. Optical and electrochemical results indicate that the synergy between the direct electron-releasing effects of the ethylenedioxy groups and the self-rigidification resulting from intramolecular interactions controls to a large extent the HOMO-LUMO gap. 相似文献
82.
Furuta P Brooks J Thompson ME Fréchet JM 《Journal of the American Chemical Society》2003,125(43):13165-13172
The site isolation of two dyes capable of electronic interaction via Forster energy transfer has been studied with the two dyes coumarin 343 and pentathiophene encapsulated by dendrons containing both solubilizing and electroactive moieties. Photoluminescence studies of mixtures of the dendritic dyes show that at high dendron generation, significant site isolation is achieved with relative emission characteristics influenced by both the degree of site isolation and the emission quantum yield of the dyes. Electroluminescence studies carried out in organic light emitting diode devices confirm that color tuning may be achieved by mixing the two encapsulated dyes in a single layer. However, selective carrier trapping by one of the core component dyes can dramatically influence the effectiveness of other components in the device. 相似文献
83.
Microchimica Acta - Es wird die Forderung erhoben, den chemischen Nachweis von E 605 in biologischem Material auf den positiven Ausfall sämtlicher drei Komponenten von E 605 (p-Nitrophenol,... 相似文献
84.
V. Wedelich W. Mehnert K. -H. Frömming 《Journal of inclusion phenomena and macrocyclic chemistry》1987,5(5):621-624
-, and -cyclodextrin and heptakis-2,6-di-O-methyl--cyclodextrin enhance the nitrosation rate of l-ephedrine if the nitrosation assay procedure (NAP test) is applied. During this reaction with -cyclodextrin a solid inclusion compound of -cyclodextrin andN-nitrosoephedrine precipitates. Solubilities and stabilities of inclusion compounds of the cyclodextrins with ephedrine and nitrosoephedrine, respectively, explain especially the catalytic effects of some cyclodextrins on ephedrine.Part of the PhD thesis of V. Wedelich, Freie Universität Berlin, 1985. 相似文献
85.
Frédérique Tellier 《合成通讯》2013,43(22):2287-2294
A stereospecific synthesis of (E,E)-9, 11, 13-tetradecatrienyl acetate and aldehyde is described. The key steps are two sequential palladium-catalyzed cross-coupling reactions between adequate organometalic reagents and the (E)-1,2-dibromoethylene. 相似文献
86.
Our recent developments concerning the fabrication of polymer microchips and their applications for biochemical analyses are reviewed. We first describe two methods of fabrication of polymer microfluidic chips, namely UV-laser photoablation and plasma etching that are well suited for the prototyping and mass fabrication of microchannel networks with integrated microelectrodes. These microanalytical systems can be coupled with various detection means including mass spectrometry, and their applications in capillary electrophoresis are presented here. We also present how UV laser photoablation can be used for the patterning of biomolecules on polymer surfaces for generating two-dimensional arrays of microspots to carry out affinity assays. Finally, the use of the microchips for the development of fast affinity and immunological assays with electrochemical detection is presented, demonstrating the potential of these polymer microchips for medical diagnostics and drug discovery. 相似文献
87.
88.
89.
90.
A Global Existence Result for the Compressible Navier–Stokes Equations in the Critical L p Framework
The present paper is dedicated to the global well-posedness issue for the barotropic compressible Navier–Stokes system in the whole space mathbbRd{mathbb{R}^d} with d ≧ 2. We aim at extending the work by Danchin (Inventiones Mathematicae 141(3):579–614, 2000) to a critical framework which is not related to the energy space. For small perturbations of a stable equilibrium state in the sense of suitable L p -type Besov norms, we establish the global existence. As a consequence, like for incompressible flows, one may exhibit a class of large highly oscillating initial velocity fields for which global existence and uniqueness holds true. In passing, we obtain new estimates for the linearized and the paralinearized systems which may be of interest for future works on compressible flows. 相似文献