全文获取类型
收费全文 | 496篇 |
免费 | 21篇 |
国内免费 | 1篇 |
专业分类
化学 | 467篇 |
晶体学 | 2篇 |
力学 | 1篇 |
数学 | 14篇 |
物理学 | 34篇 |
出版年
2023年 | 6篇 |
2022年 | 5篇 |
2021年 | 9篇 |
2020年 | 8篇 |
2019年 | 15篇 |
2018年 | 3篇 |
2017年 | 6篇 |
2016年 | 10篇 |
2015年 | 14篇 |
2014年 | 26篇 |
2013年 | 15篇 |
2012年 | 38篇 |
2011年 | 39篇 |
2010年 | 23篇 |
2009年 | 27篇 |
2008年 | 42篇 |
2007年 | 38篇 |
2006年 | 35篇 |
2005年 | 28篇 |
2004年 | 25篇 |
2003年 | 22篇 |
2002年 | 20篇 |
2001年 | 7篇 |
2000年 | 10篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 8篇 |
1996年 | 5篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 7篇 |
1991年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1982年 | 2篇 |
1980年 | 2篇 |
排序方式: 共有518条查询结果,搜索用时 15 毫秒
201.
Corinne Hanlon Shaun Frape Rhys Gwynne 《Isotopes in environmental and health studies》2017,53(5):446-465
This study provides the first characterization of the variability of bromine and chlorine stable isotopic composition in evaporites, associated residual brines, and shoreline gases in terrestrial evaporative saline lakes. The lakes investigated here are groundwater discharge locations, and include both potash-rich alkaline lakes and sodic-dominated neutral pH lakes at a variety of salinities and evaporative stages. The chlorine and bromine isotope systems behave consistently different during evaporative salt precipitation, with 37Cl more enriched in the salt than in the fluid, but 81Br more enriched in the fluid compared with the precipitated salt. The 81Br concentration of shore off-gassing was even smaller than mineral precipitate compositions. The trends observed for bromine isotopes are surprising compared with published laboratory studies, indicating that a process besides inorganic mineral precipitation is affecting δ81Br. Additional processes explored include diffusion, salt deflation, microbial and photolytic conversion to the gas phase, and oxidative bromination of organic matter.
Dedicated to Professor Peter Fritz on the occasion of his 80th birthday 相似文献
202.
Carrara C Viel S Delaurent C Ziarelli F Excoffier G Caldarelli S 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2008,194(2):303-306
Recently, it was demonstrated that pseudo-chromatographic NMR experiments could be performed using typical chromatographic solids and solvents. This first setup yielded improved separation of the spectral components of the NMR spectra of mixtures using PFG self-diffusion measurements. The method (dubbed Chromatographic NMR) was successively shown to possess, in favorable cases, superior resolving power on non-functionalized silica, compared to its LC counterpart. To further investigate the applicability of the method, we studied here the feasibility of Chromatographic NMR in common deuterated solvents. Two examples are provided, using deuterated chloroform and water, for homologous compounds soluble in these solvents, namely aromatic molecules and alcohols, respectively. 相似文献
203.
204.
Larisa Karpenko-Jereb Edyta Rynkowska Wojciech Kujawski Sarah Lunghammer Joanna Kujawa Stéphane Marais Kateryna Fatyeyeva Corinne Chappey Anne-Marie Kelterer 《Ionics》2016,22(3):357-367
The work is devoted to a computational study of three types of cationic polymeric membranes in Li+-ionic form, in water and methanol environments, at various solvation levels. The studied membranes Nafion, IonClad, and M3 possess the perfluorinated backbone; however, various side chains were terminated with the functional groups of distinctly different ionic strength. The paper discusses the structural features of the membrane-solvent clusters as well as an influence of the side chain nature on the dissociation of the functional groups and the binding energy of the solvent molecules. Additionally, the paper compares the obtained results for Li+-Nafion membrane in water with the results published earlier for H+ and Na+ forms. 相似文献
205.
206.
207.
208.
Corinne Sguineau Pascal Richomme Jean Bruneton Jacques Pusset 《Helvetica chimica acta》1992,75(7):2283-2288
The leaves of a New Caledonian celastraceae, Pleurostylia opposita (WALL .) MERRILL -METCALF , have yielded three new spermidine alkaloids, 7-hydroxypleurostyline ( 1 ), 7-hydroxycelacinnine ( 2 ), and 7′-hydroxy-7′,8′-dihydropleurostyline ( 3 ), as minor basic constituents, together with three related alkaloids pleurostyline ( 4 ), celacinnine ( 5 ), and celallocinine ( 6 ). 相似文献
209.
210.
Leroi C Bertin D Dufils PE Gigmes D Marque S Tordo P Couturier JL Guerret O Ciufolini MA 《Organic letters》2003,5(26):4943-4945
Thermolysis of alpha-alkoxyamino propionanilides produces indolinones, whereas thermal reaction of N-allylaniline derivatives with various Tordo-type alkoxyamines results in formation of indolines in the radical regime. [reaction: see text] 相似文献