全文获取类型
收费全文 | 103篇 |
免费 | 4篇 |
国内免费 | 20篇 |
专业分类
化学 | 109篇 |
综合类 | 2篇 |
物理学 | 3篇 |
综合类 | 13篇 |
出版年
2022年 | 2篇 |
2020年 | 5篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2015年 | 5篇 |
2014年 | 4篇 |
2013年 | 9篇 |
2012年 | 6篇 |
2011年 | 6篇 |
2010年 | 3篇 |
2009年 | 9篇 |
2008年 | 5篇 |
2007年 | 7篇 |
2006年 | 3篇 |
2005年 | 1篇 |
2004年 | 8篇 |
2003年 | 7篇 |
2002年 | 6篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1985年 | 2篇 |
1982年 | 1篇 |
1977年 | 2篇 |
排序方式: 共有127条查询结果,搜索用时 218 毫秒
61.
B. Srinivasa Reddy A. Naidu P. K. Dubey 《Phosphorus, sulfur, and silicon and the related elements》2013,188(5):598-605
Abstract Condensation of 2-mercapto-3H-quinazolin-4-one (1) with chloroacetic acid gave 4-oxo-3,4-dihydroquinazoline-2-yl-sulfanyl)-acetic acid (2) that with anthranilamide (3) gave 2-(4-oxo-3,4-dihydroquinazolin-2-ylsulfanylmethyl)-3H-quinazolin-4-one (4). Oxidation of 4 with sodium hypochlorite in alkaline medium gave the novel product, 2-(4-oxo-3,4- dihydroquinazolin-2-ylsulfinyl methyl)-3H -quinazolin-4-one) (5). The entire sequences of reactions in this work have been carried out using eco-friendly solvents and green conditions. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. 相似文献
62.
63.
Thermodynamic and kinetic acidities of 6-tert-butyl-2-hydroxy-4-triphenylmethylphenoxyl during its interaction with triethylamine in toluene have been studied by ESR. It has been shown that the protolysis of this radical is a two-pathway process, since tautomeric transitions, i.e. ammonium ion migration between oxygen atoms of the semiquinone radical anion, have been detected in the reaction products, that is, in contact ion pairs of the corresponding semiquinone radicals.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No 1, pp. 81–84, January, 1993. 相似文献
64.
An extensive survey of the literature published in analytical and pharmaceutical chemistry journals has been conducted and analytical methods which were developed and used for the determination of some of the COX-2 inhibitors, a subclass of non-steroidal anti-inflammatory drugs (NSAIDs) in bulk drugs, formulations, and biological fluids have been reviewed. This review covers the time period from 1999 to present, during which over 140 analytical procedures including chromatographic, spectrometric, electrophoretic and voltammetric techniques were reported. Presented applications concern analysis of coxibs from pharmaceutical formulations and biological samples. 相似文献
65.
为了提高磺化聚芳醚砜(SPAES)类质子交换膜的质子导电率及尺寸稳定性,制备了一系列N型(或T型)SPAES共混质子交换膜.采用共混方式,利用具有不同离子交换容量(IEC)的磺酸钠盐(或磺酸三乙胺盐)型SPAES进行了制备.通过测试得到共混膜的膜面方向及厚度方向的尺寸变化率.采用电化学阻抗光谱技术测定共混膜在平面方向的质子导电率.结果表明:T型共混膜的共混性高于N型共混膜;共混膜的尺寸稳定性明显增强,如IEC为2.07 meq/g的TS0共混膜在30℃水中膜平面方向及厚度方向的尺寸变化率仅为0.14和0.15;共混膜在温度60℃相对湿度30%~100%下质子导电率(8~247 mS/cm)与纯SPAES膜相当. 相似文献
66.
以甲基丙烯酸羟乙酯和二乙烯酮为原料,在碱性催化下合成了甲基丙烯酸乙酰乙酸乙二醇双酯(2-AAEMA),研究了催化剂(NEt_3)用量,反应温度等对收率的影响,并以~1H-NMR表征了2-AAEMA的结构。 相似文献
67.
A. A. Yartseva L. Sh. Koldrov S. S. Galibeev V. P. Arkhireev N. I. Naumkina I. A. Litvinov A. T. Gubaidullin 《Journal of Structural Chemistry》2007,48(6):1138-1144
The molecular complexes of 1,3,5-tris-m-chlorophenylisocyanurate and ε-caprolactone were synthesized by the reaction of the latter with 3-chlorophenylisocyanate in the presence of triethylamine. Single crystals were grown, and the molecular and crystal structures of the synthesized complexes were investigated. 相似文献
68.
谢钦铭 《南昌大学学报(理科版)》1992,16(1):1
本文采用了毒理学、组织化学等方法研究了三乙胺对水生生物的毒性及毒理。测定了三乙胺对白鲢、草鱼、金鱼、泥鳅、罗非鱼、湖螺、隆线溞的急性毒性,它们的96h TLm依次是52.90,56.58,107.16,181.42,42.34,25.92,17.70mg/L。测定了三乙胺对斜生栅藻光合作用的抑制率,当三乙胺浓 相似文献
69.
70.
Sparidans RW Dost F Crommentuyn KM Huitema AD Schellens JH Beijnen JH 《Biomedical chromatography : BMC》2006,20(1):72-76
Atazanavir is the most recently introduced protease inhibitor for the suppression of the anti-human immunodeficiency virus. A sensitive and selective reversed-phase liquid chromatographic assay for this drug in human plasma has been developed and validated. Atazanavir was isolated from a 500 microL plasma sample using liquid-liquid extraction with dichloromethane. After evaporation and reconstitution of the extract the sample was analysed using liquid chromatography and ultraviolet detection at 280 nm. In the evaluated concentration range (44-4395 ng/mL atazanavir), intra-day precisions were < or =7% and inter-day precisions were < or =14%. Accuracies between 96 and 106% were found. The lower limit of quantification was 44 ng/mL with an intra-day precision of 7%, an inter-day precision of 14% and an accuracy of 87%. There was no interference from 32 tested potentially co-administrated drugs and metabolites. The usefulness of the assay was demonstrated for samples obtained from an HIV-infected patient treated with atazanavir. 相似文献