全文获取类型
收费全文 | 796篇 |
免费 | 20篇 |
国内免费 | 8篇 |
专业分类
化学 | 612篇 |
晶体学 | 8篇 |
力学 | 12篇 |
数学 | 122篇 |
物理学 | 70篇 |
出版年
2022年 | 5篇 |
2021年 | 3篇 |
2020年 | 8篇 |
2019年 | 7篇 |
2018年 | 5篇 |
2017年 | 6篇 |
2016年 | 9篇 |
2015年 | 16篇 |
2014年 | 13篇 |
2013年 | 29篇 |
2012年 | 44篇 |
2011年 | 28篇 |
2010年 | 27篇 |
2009年 | 23篇 |
2008年 | 44篇 |
2007年 | 53篇 |
2006年 | 43篇 |
2005年 | 51篇 |
2004年 | 56篇 |
2003年 | 34篇 |
2002年 | 31篇 |
2001年 | 12篇 |
2000年 | 11篇 |
1999年 | 16篇 |
1998年 | 16篇 |
1997年 | 9篇 |
1996年 | 14篇 |
1995年 | 19篇 |
1994年 | 12篇 |
1993年 | 15篇 |
1992年 | 11篇 |
1991年 | 9篇 |
1990年 | 13篇 |
1989年 | 9篇 |
1988年 | 9篇 |
1987年 | 9篇 |
1986年 | 12篇 |
1985年 | 8篇 |
1984年 | 11篇 |
1983年 | 8篇 |
1982年 | 7篇 |
1981年 | 15篇 |
1980年 | 15篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 2篇 |
1975年 | 4篇 |
1970年 | 1篇 |
1962年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有824条查询结果,搜索用时 15 毫秒
61.
62.
Selected ortho-disubstituted pyridines and thiopenes react with Michael acceptors to give functionalized quinolines or benzo[b]thiopenes, respectively. 相似文献
63.
64.
Effects of Refractive Index and Viscosity on Fluorescence and Anisotropy Decays of Enhanced Cyan and Yellow Fluorescent Proteins 总被引:1,自引:1,他引:0
The fluorescence lifetime strongly depends on the immediate environment of the fluorophore. Time-resolved fluorescence measurements of the enhanced forms of ECFP and EYFP in water–glycerol mixtures were performed to quantify the effects of the refractive index and viscosity on the fluorescence lifetimes of these proteins. The experimental data show for ECFP and EYFP two fluorescence lifetime components: one short lifetime of about 1 ns and a longer lifetime of about 3.7 ns of ECFP and for EYFP 3.4. The fluorescence of ECFP is very heterogeneous, which can be explained by the presence of two populations: a conformation (67% present) where the fluorophore is less quenched than in the other conformation (33% present). The fluorescence decay of EYFP is much more homogeneous and the amplitude of the short fluorescence lifetime is about 5%. The fluorescence anisotropy decays show that the rotational correlation time of both proteins scales with increasing viscosity of the solvent similarly as shown earlier for GFP. The rotational correlation times are identical for ECFP and EYFP, which can be expected since both proteins have the same shape and size. The only difference observed is the slightly lower initial anisotropy for ECFP as compared to the one of EYFP. 相似文献
65.
66.
Validzic IL van Hooijdonk G Oosterhout S Kegel WK 《Langmuir : the ACS journal of surfaces and colloids》2004,20(8):3435-3440
We show that a single geometrical rule underlies the stability of "polyoxomolybdates", the variety of clusters of molybdenum(VI) oxide in (acidified) aqueous solution that are found experimentally. We predict that upon increasing the proton or total molybdenum oxide concentration, the average size of the clusters increases. We compare our predictions with results from ultracentrifugation experiments and with data in the literature. Finally, it is shown that the formation of metal oxide clusters is thermodynamically equivalent to the formation of surfactant micelles. 相似文献
67.
68.
In an earlier article, Willem H. Haemers has determined the minimum number of parallel classes in a resolvable 2‐(qk,k,1) covering for all k ≥ 2 and q = 2 or 3. Here, we complete the case q = 4, by construction of the desired coverings using the method of simulated annealing. Secondly, we look at equitable resolvable 2‐(qk,k,1) coverings. These are resolvable coverings which have the additional property that every pair of points is covered at most twice. We show that these coverings satisfy k < 2q ? , and we give several examples. In one of these examples, k > q. © 2003 Wiley Periodicals, Inc. J Combin Designs 11: 113–123, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jcd.10024 相似文献
69.
70.
Summary Seven new coordination compounds are reported with the cyclicpolyether 18-crown-6 as the ligand,viz. [Mg(18-crown-6) (H2O)2](SbCl6)2, [M(18-crown-6)(MeNO6)2](SbCl6)2 with M is Ca2+ and Sr2+, [M(18-crown-6)(MeNO2)](SbCl6)2 with M is Mn2+ and Co2+, and [M(18-crown-6)](SbCl6)2 with M is Ni2+ and Zn2+. 相似文献