全文获取类型
收费全文 | 875篇 |
免费 | 11篇 |
国内免费 | 9篇 |
专业分类
化学 | 516篇 |
晶体学 | 3篇 |
力学 | 47篇 |
数学 | 64篇 |
物理学 | 265篇 |
出版年
2019年 | 5篇 |
2017年 | 6篇 |
2016年 | 15篇 |
2015年 | 8篇 |
2014年 | 8篇 |
2013年 | 34篇 |
2012年 | 12篇 |
2011年 | 28篇 |
2010年 | 24篇 |
2009年 | 17篇 |
2008年 | 37篇 |
2007年 | 43篇 |
2006年 | 41篇 |
2005年 | 33篇 |
2004年 | 35篇 |
2003年 | 37篇 |
2002年 | 33篇 |
2001年 | 19篇 |
2000年 | 24篇 |
1999年 | 19篇 |
1998年 | 11篇 |
1997年 | 16篇 |
1996年 | 14篇 |
1995年 | 14篇 |
1994年 | 13篇 |
1993年 | 17篇 |
1992年 | 17篇 |
1991年 | 15篇 |
1990年 | 20篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 10篇 |
1985年 | 15篇 |
1984年 | 21篇 |
1983年 | 11篇 |
1982年 | 13篇 |
1981年 | 17篇 |
1980年 | 21篇 |
1979年 | 13篇 |
1978年 | 16篇 |
1977年 | 6篇 |
1976年 | 9篇 |
1975年 | 14篇 |
1974年 | 10篇 |
1973年 | 13篇 |
1972年 | 6篇 |
1971年 | 5篇 |
1970年 | 5篇 |
1969年 | 6篇 |
排序方式: 共有895条查询结果,搜索用时 15 毫秒
101.
Jeffery BJ Whitelaw EL Garcia-Vivo D Stewart JA Mahon MF Davidson MG Jones MD 《Chemical communications (Cambridge, England)》2011,47(45):12328-12330
In this paper we demonstrate the utility of Group 4 metals for the well-controlled and stereoselective (syndiotactic) ring opening polymerization (ROP) of rac-β-butyrolactone (BBL) and their ability to form copolymers. 相似文献
102.
Dr. Anirban Bardhan Dr. Wes Brown Savannah Albright Prof. Michael Tsang Prof. Lance A. Davidson Prof. Alexander Deiters 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(17):e202318773
Conditionally controlled antisense oligonucleotides provide precise interrogation of gene function at different developmental stages in animal models. Only one example of small molecule-induced activation of antisense function exist. This has been restricted to cyclic caged morpholinos that, based on sequence, can have significant background activity in the absence of the trigger. Here, we provide a new approach using azido-caged nucleobases that are site-specifically introduced into antisense morpholinos. The caging group design is a simple azidomethylene (Azm) group that, despite its very small size, efficiently blocks Watson–Crick base pairing in a programmable fashion. Furthermore, it undergoes facile decaging via Staudinger reduction when exposed to a small molecule phosphine, generating the native antisense oligonucleotide under conditions compatible with biological environments. We demonstrated small molecule-induced gene knockdown in mammalian cells, zebrafish embryos, and frog embryos. We validated the general applicability of this approach by targeting three different genes. 相似文献
103.
D. W. Davidson Y. P. Handa C. I. Ratcliffe J. A. Ripmeester J. S. Tse J. R. Dahn 《Molecular Crystals and Liquid Crystals》2013,570(1-2):141-149
Low-temperature neutron and X-ray diffraction studies show the gas hydrates of oxygen and nitrogen to be structure II (Fd3m), as recently found also for the hydrates of the small argon and krypton molecules. New lattice parameters of three structure I and 14 structure II hydrates from powder X-ray diffraction at 170 K are reported. The thermal expansion coefficient of tetrahydrofuran hydrate was determined from X-ray diffraction at some 50 temperatures between 18 and 263 K and found to be three times as great as for ice near 100 K and 30% higher near 250 K. Lattice parameters qf 40 type II clathrate hydrates are compared at 0°C and found to lie within 0.10 Å of 17.30 Å. 相似文献
104.
Zekai Hong King-Yiu Lam Ritobrata Sur Shengkai Wang David F. Davidson Ronald K. Hanson 《Proceedings of the Combustion Institute》2013,34(1):565-571
Hydrogen peroxide (H2O2) and hydroperoxy (HO2) reactions present in the H2O2 thermal decomposition system are important in combustion kinetics. H2O2 thermal decomposition has been studied behind reflected shock waves using H2O and OH diagnostics in previous studies (Hong et al. (2009) [9] and Hong et al. (2010) [6,8]) to determine the rate constants of two major reactions: H2O2 + M → 2OH + M (k1) and OH + H2O2 → H2O + HO2 (k2). With the addition of a third diagnostic for HO2 at 227 nm, the H2O2 thermal decomposition system can be comprehensively characterized for the first time. Specifically, the rate constants of two remaining major reactions in the system, OH + HO2 → H2O + O2 (k3) and HO2 + HO2 → H2O2 + O2 (k4) can be determined with high-fidelity.No strong temperature dependency was found between 1072 and 1283 K for the rate constant of OH + HO2 → H2O + O2, which can be expressed by the combination of two Arrhenius forms: k3 = 7.0 × 1012 exp(550/T) + 4.5 × 1014 exp(?5500/T) [cm3 mol?1 s?1]. The rate constants of reaction HO2 + HO2 → H2O2 + O2 determined agree very well with those reported by Kappel et al. (2002) [5]; the recommendation therefore remains unchanged: k4 = 1.0 × 1014 exp(?5556/T) + 1.9 × 1011+exp(709/T) [cm3 mol?1 s?1]. All the tests were performed near 1.7 atm. 相似文献
105.
W. Hiltner H. A. Freye R. J. Fosbinder J. W. Schoonover M. Kilpatrick E. F. Chase L. C. Riesch A. Janke F. Sekera G. F. Davidson J. O. Burton H. Matheson S. F. Acree G. Haugaard F. L. Vodret F. Hovorka W. C. Dearing T. Mikawa E. Newbery A. Itano S. Arakawa T. R. Ball W. B. Schmidt K. S. Bergstresser E. Vellinger A. E. Lorch F. Lux W. von Brehmer M. Déribéré A. F. Peters und A. Osol 《Fresenius' Journal of Analytical Chemistry》1935,103(7-8):285-292
Ohne Zusammenfassung 相似文献
106.
D. R. Koolhaas R. C. Roark Betrem N. S. K. Kaisha C. D. V. Georgi Cunn Lay Telk W. M. Davidson P. W. Danckwortt H. Budde G. Baumgarten E. P. Clark W. A. Gersdorff S. Takei S. Miyajima M. Ono E. Späth und O. Pesta 《Fresenius' Journal of Analytical Chemistry》1935,102(3-4):135-141
Ohne Zusammenfassung 相似文献
107.
108.
F. Krauss E. H. Riesenfeld F. Feld J. Kendall A. W. Davidson und W. Böttger 《Fresenius' Journal of Analytical Chemistry》1926,69(4):178-179
Ohne Zusammenfassung 相似文献
109.
110.
R. XuF.A. Davidson M.A.J. Chaplain 《Journal of Mathematical Analysis and Applications》2002,269(1):256-277
A two-species ratio-dependent predator-prey model with distributed time delay is investigated. It is shown that the system is persistent under some appropriate conditions, and sufficient conditions are obtained for both the local and global stability of the positive equilibrium of the system. 相似文献