全文获取类型
收费全文 | 395篇 |
免费 | 11篇 |
国内免费 | 3篇 |
专业分类
化学 | 289篇 |
晶体学 | 3篇 |
力学 | 1篇 |
数学 | 67篇 |
物理学 | 49篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 3篇 |
2017年 | 9篇 |
2016年 | 6篇 |
2015年 | 3篇 |
2014年 | 8篇 |
2013年 | 15篇 |
2012年 | 29篇 |
2011年 | 19篇 |
2010年 | 12篇 |
2009年 | 13篇 |
2008年 | 18篇 |
2007年 | 26篇 |
2006年 | 19篇 |
2005年 | 29篇 |
2004年 | 28篇 |
2003年 | 13篇 |
2002年 | 15篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 8篇 |
1997年 | 4篇 |
1996年 | 10篇 |
1995年 | 8篇 |
1994年 | 8篇 |
1993年 | 6篇 |
1992年 | 8篇 |
1991年 | 3篇 |
1990年 | 12篇 |
1989年 | 14篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1971年 | 2篇 |
1907年 | 2篇 |
排序方式: 共有409条查询结果,搜索用时 31 毫秒
101.
Hunka DE Herman DC Lormand KD Jaramillo DM Land DP 《Langmuir : the ACS journal of surfaces and colloids》2005,21(18):8333-8337
The decomposition of 1,1-dichloroethene on Pd(111) is investigated using conventional thermal desorption, laser-induced thermal desorption (LITD), and FT reflection absorption infrared spectroscopy (FT-RAIRS). The decomposition mechanism produces at least three hydrocarbon surface intermediates, including ethylidyne. Thermal desorption results differ between high and low coverages because of relative surface concentrations of Cl and H in combination with kinetic effects. 相似文献
102.
103.
Larrosa I Da Silva MI Gómez PM Hannen P Ko E Lenger SR Linke SR White AJ Wilton D Barrett AG 《Journal of the American Chemical Society》2006,128(43):14042-14043
The first total synthesis of (+)-clavilactone B, a potent antifungal agent and novel tyrosine kinase inhibitor, is described. The absolute configuration of clavilactones has been unambiguously established by using Sharpless asymmetric epoxidation to generate the enantiomerically pure substrate. The strategy highlights the use of a powerful and convergent three-component benzyne coupling with a methylallyl Grignard and a chiral epoxy-aldehyde to generate two C-C bonds and install the carbon skeleton of clavilactone. Oxidative lactonization, ten-membered ring construction by ring closing metathesis, and oxidation gave clavilactone B. 相似文献
104.
In situ chemical oxidation of aniline by persulfate with iron(Ⅱ) activation at ambient temperature 总被引:1,自引:0,他引:1
Donna E.Fennell 《中国化学快报》2010,21(8):911-193
<正>The kinetics of aniline degradation by persulfate processes with iron(Ⅱ) activation at ambient temperature was investigated in this study.With iron(Ⅱ) as initiator,the oxidation reactions were found to follow a biphasic rate phenomenon:a rapid transformation followed by a slow but sustained oxidation process.In the first 30 s,the reaction mainly relies on the persulfate-Fe~(2+) reaction in which aniline is oxidized rapidly.After 30 s,the aniline was still oxidized but the rate of reaction tended to be slower and the rates were clearly linear-proportional.After the initial fast oxidation,the reactions appeared to follow a pseudo-first-order model. 相似文献
105.
Douglas E. McIntyre D.John Faulkner Donna Van Engen Jon Clardy 《Tetrahedron letters》1979,20(43):4163-4166
The major antibacterial metabolite in the sponge sp. was shown to be an isoquinoline quinone, renierone (). The structure of renierone () was defined by X-ray crystallography. 相似文献
106.
Amy?S.?Cannon Alessandra?Morelli Whitney?Pressler John?C.?WarnerEmail author Donna?Guarrera 《Journal of Sol-Gel Science and Technology》2005,36(2):157-162
Sol-gel deposited titanium dioxide films are used for a wide range of applications. One of the drawbacks to these films is
that they must be heated in excess of 400∘C in order to obtain durability. We have found that the processing temperature required to prepare sol-gel derived titanium
dioxide films can be significantly reduced by the addition of small amounts of trimesic acid. The addition of this material
provides a low energy pathway for the growth of titanium dioxide particles. Titanium dioxide films prepared with trimesic
acid show significantly enhanced physical properties with respect to cracking and peeling. Scanning Electron Microscopy and
X-Ray Diffraction analyses of films are presented. 相似文献
107.
Lawrence L. Martin Susan J. Scott Linda L. Setescak Donna Van Engen 《Journal of heterocyclic chemistry》1987,24(6):1541-1549
1,2,3,4-Tetrahydrobenzo[c]-1,5-naphthyridine ( 5a ) was prepared by a novel synthetic route involving the rearrangement of (±)-(Z)-1,10a-dihydropyrrolo[1,2-b]isoquinoline-3,10(2H,5H)-dione oxime to afford 1,4-dihydrobenzo[c]-1,5-naphthyridin-2(3H)-one, which was reduced to 5a. The cholinomimetic activity observed with 5a prompted the synthesis and biological evaluation of additional analogues. 相似文献
108.
Experimental kinetic data coupled with kinetic modeling implicates a tetrameric transition state in the Soai autocatalytic alkylation of pyrimidyl aldehydes. The kinetic model accurately predicts both the reaction rate and the amplification in enantiomeric excess observed in reactions carried out under a wide range of conditions. These studies reveal the Soai reaction to be an example of true autocatalytic efficiency in a template-directed "minimal system" for self-replication. 相似文献
109.
110.
Toby M. Chapman Donna M. Rakiewicz-Nemeth John Swestock Ramazan Benrashid 《Journal of polymer science. Part A, Polymer chemistry》1990,28(6):1473-1482
Segmented polyurethanes with N-alkylated amides as soft blocks as prepared. Comparisons are made with both a poly(ester urethane) and a poly(ether urethane) with the same hard block; the poly(amide urethane) is more hydrolytically stable than the polyester containing material and demonstrates greater thermooxidative stability than that with the polyether moiety. The aliphatic poly(amide urethane)s remain transparent upon exposure to uv light. 相似文献