全文获取类型
收费全文 | 1237篇 |
免费 | 40篇 |
国内免费 | 7篇 |
专业分类
化学 | 869篇 |
晶体学 | 16篇 |
力学 | 23篇 |
数学 | 175篇 |
物理学 | 201篇 |
出版年
2023年 | 7篇 |
2022年 | 13篇 |
2021年 | 16篇 |
2020年 | 23篇 |
2019年 | 14篇 |
2018年 | 13篇 |
2017年 | 17篇 |
2016年 | 23篇 |
2015年 | 25篇 |
2014年 | 31篇 |
2013年 | 71篇 |
2012年 | 84篇 |
2011年 | 71篇 |
2010年 | 45篇 |
2009年 | 19篇 |
2008年 | 62篇 |
2007年 | 70篇 |
2006年 | 56篇 |
2005年 | 51篇 |
2004年 | 56篇 |
2003年 | 51篇 |
2002年 | 37篇 |
2001年 | 17篇 |
2000年 | 19篇 |
1998年 | 9篇 |
1997年 | 12篇 |
1996年 | 14篇 |
1995年 | 19篇 |
1994年 | 17篇 |
1993年 | 13篇 |
1992年 | 17篇 |
1991年 | 15篇 |
1990年 | 12篇 |
1989年 | 15篇 |
1988年 | 9篇 |
1987年 | 11篇 |
1984年 | 11篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 14篇 |
1980年 | 10篇 |
1979年 | 8篇 |
1978年 | 14篇 |
1977年 | 12篇 |
1976年 | 15篇 |
1975年 | 14篇 |
1974年 | 11篇 |
1973年 | 9篇 |
1972年 | 13篇 |
1970年 | 9篇 |
排序方式: 共有1284条查询结果,搜索用时 15 毫秒
91.
Novel PI analogues selectively block activation of the pro-survival serine/threonine kinase Akt 总被引:8,自引:0,他引:8
Kozikowski AP Sun H Brognard J Dennis PA 《Journal of the American Chemical Society》2003,125(5):1144-1145
The synthesis from l-quebrachitol of a series of 3-deoxygenated ether lipid-type phosphatidylinositol (PI) analogues is reported, that selectively block activation of Akt and downstream substrates without affecting activation of the upstream kinase, PDK-1, or other kinases downstream of ras such as MAPK in H157 and H1703 lung cancer cells that have high levels of constitutively active Akt. The 2-hydroxyl in these compounds was deleted or alkylated with the intent to preclude metabolic degradation of these compounds by PI-specific phospholipase C (PI-PLC). PI analogues with phosphate linkers are more effective than those with carbonate linkers. Specific inhibition of Akt by these compounds validates ligand design targeted to the PH domains of crucial signaling proteins, thus providing a unique class of possible cancer therapeutics. 相似文献
92.
[reaction: see text]. (-)-PF1163B, a new macrocyclic antifungal antibiotic isolated from Streptomyces sp., has been prepared in eight steps from (S)-citronellene. The key step is a ring-closing metathesis reaction of an ester and amide derivative obtained from a substituted N-methyl-l-tyrosine. 相似文献
93.
Alexander I. Nosich Elena I. Smotrova Svetlana V. Boriskina Trevor M. Benson Phillip Sewell 《Optical and Quantum Electronics》2007,39(15):1253-1272
Research into microdisk lasers demonstrates new achievements both in the technology and in the associated physical effects
and applications. Melting and rounding of the disk edge boosts the Q-factors due to improved surface smoothness. In-plane
cavity shape is widely used as a design instrument. Optimal shaping of pumped area lowers the threshold power. Photonic molecules
made of several microdisks as “photonic atoms” show lasing at several closely spaced frequencies. A microdisk with a single
quantum dot as an active region is considered as the most promising system for realisation of a single photon emitter necessary
for quantum computing. These new effects and devices can be simulated with accurate numerical techniques, developed recently
for “warm-cavity” linear modelling, that are able to bring a new vision of the physics of lasing. 相似文献
94.
95.
96.
97.
Wilhelm Bachmann 《Colloid and polymer science》1918,23(3):85-100
Ohne Zusammenfassung 相似文献
98.
Paul Bachmann 《Mathematische Annalen》1881,18(3):449-468
Ohne Zusammenfassung 相似文献
99.
In this work we present a numerical method for solving the incompressible Navier–Stokes equations in an environmental fluid mechanics context. The method is designed for the study of environmental flows that are multiscale, incompressible, variable‐density, and within arbitrarily complex and possibly anisotropic domains. The method is new because in this context we couple the embedded‐boundary (or cut‐cell) method for complex geometry with block‐structured adaptive mesh refinement (AMR) while maintaining conservation and second‐order accuracy. The accurate simulation of variable‐density fluids necessitates special care in formulating projection methods. This variable‐density formulation is well known for incompressible flows in unit‐aspect ratio domains, without AMR, and without complex geometry, but here we carefully present a new method that addresses the intersection of these issues. The methodology is based on a second‐order‐accurate projection method with high‐order‐accurate Godunov finite‐differencing, including slope limiting and a stable differencing of the nonlinear convection terms. The finite‐volume AMR discretizations are based on two‐way flux matching at refinement boundaries to obtain a conservative method that is second‐order accurate in solution error. The control volumes are formed by the intersection of the irregular embedded boundary with Cartesian grid cells. Unlike typical discretization methods, these control volumes naturally fit within parallelizable, disjoint‐block data structures, and permit dynamic AMR coarsening and refinement as the simulation progresses. We present two‐ and three‐dimensional numerical examples to illustrate the accuracy of the method. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
100.
R. Zsigmondy W. Bachmann und E. de Haën 《Fresenius' Journal of Analytical Chemistry》1919,58(3):116-117
Ohne Zusammenfassung 相似文献