全文获取类型
收费全文 | 114篇 |
免费 | 1篇 |
专业分类
化学 | 81篇 |
力学 | 5篇 |
数学 | 1篇 |
物理学 | 28篇 |
出版年
2022年 | 1篇 |
2021年 | 3篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2016年 | 2篇 |
2014年 | 2篇 |
2013年 | 12篇 |
2012年 | 5篇 |
2011年 | 3篇 |
2010年 | 6篇 |
2009年 | 6篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 3篇 |
2005年 | 3篇 |
2004年 | 3篇 |
2003年 | 1篇 |
2002年 | 3篇 |
2000年 | 2篇 |
1999年 | 6篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1978年 | 4篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1970年 | 4篇 |
1969年 | 3篇 |
1968年 | 1篇 |
排序方式: 共有115条查询结果,搜索用时 15 毫秒
1.
The reaction of the cluster complex HCC[Co2(CO)6]CCo3(CO)9 with (or without) BrCCo3(CO)9 under Cadiot-Chodkiewicz coupling conditions gave the unusual alkynyl carboxamide complex C2H5N(H)C(O)CC[Co2(CO)6]CCo3(CO)9 rather than a coupled product containing two tricobalt cluster units. Steric demands imposed by the Co3 cluster allow attack at the least hindered alkyne carbon and stabilise the formed ynamine, so allowing subsequent CO insertion. The product has been characterised by X-ray crystallography. 相似文献
2.
3.
4.
James P. Kutney Toshio Honda Peter M. Kazmaier Norman J. Lewis Brian R. Worth 《Helvetica chimica acta》1980,63(2):366-374
The synthesis and conformational analysis of (3′R)-3-hydroxyleurosidine ( 5 ), (3′S)-3-hydroxyleurosidine ( 10 ), (3′S)-3-acetoxy-4′-deoxyleurosidine ( 15 ), (3′R)-3-acetoxy-4′-deoxyleurosidine ( 23 ), (3′R)-3-acetoxy-4′-deoxyvinblastine ( 16 ), (3′S)-3-acetoxy-4′-deoxyleurosidine ( 28 ) is discussed. 相似文献
5.
6.
Robert H. Higgins Quentin L. Eaton Leroy Worth Myra V. Peterson 《Journal of heterocyclic chemistry》1987,24(1):255-259
Cyclization of either the tetrahydropyranyl or trimethylsilyl ether of 1-(alkylamino)-3-chloro-2-propanols 1 followed by cleavage of the azetidinyl ether provides a general method for the preparation of 1-alkyl-3-azetidinols. Unhindered amines provide a more facile preparation of derivatives of 1 , or its ethers, than do hindered amines, while hindered derivatives of 1 undergo more facile ring closure. 相似文献
7.
8.
9.
A. Gallegos Saliner I. Tsakovska M. Pavan G. Patlewicz A. P. Worth 《SAR and QSAR in environmental research》2013,24(3-4):331-342
The German Federal Institute for Risk Assessment (BfR) has developed a Decision Support System (DSS) to assess certain hazardous properties of pure chemicals, including skin and eye irritation/corrosion. The BfR–DSS is a rule-based system that could be used for the regulatory classification of chemicals in the European Union. The system is based on the combined use of two predictive approaches: exclusion rules based on physicochemical cut-off values to identify chemicals that do not exhibit a certain hazard (e.g., skin irritation/corrosion), and inclusion rules based on structural alerts to identify chemicals that do show a particular toxic potential. The aim of the present study was to evaluate the structural inclusion rules implemented in the BfR–DSS for the prediction of skin irritation and corrosion. The following assessments were performed: (a) a confirmation of the structural rules by rederiving them from the original training set (1358 substances), and (b) an external validation by using a test set of 200 chemicals not used in the derivation of the rules. It was found as a result that the test data set did not match the training set relative to the inclusion of structural alerts associated with skin irritation/corrosion, albeit some skin irritants were in the test set. 相似文献
10.
Two new diterpenes related to bertyadionol have been isolated and their structure determined. Degradation of bertyadionol to 2R-methylsuccinic acid provided the configuration at C-2 for this compound. The absolute stereochemistry of bertyadionol and its congeners was established by application of INDOR and NOE techniques. 相似文献