全文获取类型
收费全文 | 284篇 |
免费 | 13篇 |
专业分类
化学 | 239篇 |
力学 | 2篇 |
数学 | 27篇 |
物理学 | 29篇 |
出版年
2022年 | 15篇 |
2021年 | 25篇 |
2020年 | 6篇 |
2019年 | 10篇 |
2018年 | 8篇 |
2017年 | 10篇 |
2016年 | 20篇 |
2015年 | 14篇 |
2014年 | 19篇 |
2013年 | 15篇 |
2012年 | 20篇 |
2011年 | 26篇 |
2010年 | 14篇 |
2009年 | 11篇 |
2008年 | 13篇 |
2007年 | 18篇 |
2006年 | 19篇 |
2005年 | 12篇 |
2004年 | 6篇 |
2003年 | 2篇 |
2002年 | 3篇 |
2001年 | 1篇 |
1992年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1967年 | 2篇 |
1966年 | 2篇 |
1943年 | 1篇 |
排序方式: 共有297条查询结果,搜索用时 0 毫秒
291.
292.
The MCSCF calculations indicate that both triplet and singlet state of biradical di-para-xylylene can exist during polymerization of parylene in gas phase and both can potentially react with vinyl molecules. The singlet-state open-shell dimer turned out to exhibit multiconfigurational character. In the case of triplet state of the dimer two mechanisms of the reactions with various species containing vinyl groups have been examined at the B3LYP/6-31G level. The kinetic and thermodynamical barriers have been estimated for the reaction path involving the π-bond cleavage as well as for the route describing the hydrogen atom transfer. It was found that the overall reactions are thermodynamically favorable, whereas appropriate kinetic barriers for certain derivatives are very small (close to 0 kcal/mol) which in turn makes allowances for easy reactivity under accessible conditions. The calculated mechanisms indicate the influence of substituents in vinyl groups for reactivity of parylene during LPCVD process. 相似文献
293.
294.
Sara Janowska Dmytro Khylyuk Sylwia Andrzejczuk Monika Wujec 《Molecules (Basel, Switzerland)》2022,27(10)
The emergence of drug-resistant bacterial strains continues to be one of the major challenges of medicine. For this reason, the importance of searching for novel structures of antibacterial drugs chemically different from the currently known antibiotics is still of great importance. In this study, we synthesized the thiosemicarbazide and 1,3,4-thiadiazole derivatives and tested them for antibacterial activity. In in vitro tests, we examined the activity of the synthesized substances against Gram-positive and Gram-negative bacteria strains. While all 1,3,4-thiadiazoles tested lacked significant activity, the antimicrobial response of the thiosemicarbazides was moderate and it was also dependent on the type and position of the substituent on the phenyl ring. The highest activity towards all Gram-positive bacteria strains was shown by all three linear compounds containing the trifluoromethylphenyl group in the structure. The MIC (minimum inhibitory concentration) values were in the range of 3.9–250 µg/mL. Additionally, we try to explain the mechanism of the antibacterial activity of the tested compounds using the molecular docking to DNA gyrase and topoisomerase IV, following previous reports on the molecular basis of the activity of thiosemicarbazides. Docking simulations allow the purposing dual mechanism of the antibacterial activity of the synthesized compounds through inhibition of topoisomerase IV DNA gyrase with the moderate prevalence of the topoisomerase pathway. 相似文献
295.
296.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献
297.
The polycondensation of methyl α-D-mannopyranoside ( 1 ) with 1,n-bis(formylphenoxy)alkanes ( 2 ), using acidic catalysts, leads to the formation of linear polymers and macrocyclic compounds. The structure of the polymer and macrocycles was determined by 1H, 13C NMR spectroscopy and ESI-MS analysis. 相似文献