全文获取类型
收费全文 | 122篇 |
免费 | 3篇 |
国内免费 | 1篇 |
专业分类
化学 | 77篇 |
晶体学 | 2篇 |
力学 | 1篇 |
数学 | 39篇 |
物理学 | 7篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 6篇 |
2012年 | 8篇 |
2011年 | 6篇 |
2010年 | 6篇 |
2009年 | 3篇 |
2008年 | 10篇 |
2007年 | 4篇 |
2006年 | 7篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 6篇 |
2000年 | 2篇 |
1997年 | 4篇 |
1995年 | 1篇 |
1994年 | 6篇 |
1993年 | 1篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1967年 | 2篇 |
排序方式: 共有126条查询结果,搜索用时 15 毫秒
1.
Pressure-supported packed capillary electrochromatography (CEC) and packed capillary high-performance liquid chromatography (pHPLC) have been coupled on-line to electrospray ionization-mass spectrometry (ESI-MS) and coordination ion spray-mass spectrometry (CIS-MS). Separation of enantiomers of barbiturates and chlorinated alkyl phenoxypropanoates were performed on a permethylated beta-cyclodextrin stationary phase by pressure-supported CEC. For on-line detection with ESI- and CIS-MS, a modified sheath-liquid interface was used. CIS-MS is a universal, novel ionization technique which improves the selectivity as well as the sensitivity. Charged complexes were formed through the addition of central complexing ions such as silver(I), cobalt(II), copper(II), and lithium(I) to the sheath flow. Advantages of CIS-MS detection compared to the ESI-MS mode are discussed. In the CIS-MS mode, increased sensitivity and high selectivity was attained through different possibilities of complexation. The superiority of pressure-supported CEC compared to pHPLC in the hyphenation with CIS-MS is demonstrated. 相似文献
2.
3.
4.
5.
Müller C Wasserberg D Weemers JJ Pidko EA Hoffmann S Lutz M Spek AL Meskers SC Janssen RA van Santen RA Vogt D 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(16):4548-4559
A series of donor-functionalized pyrylium salts have been prepared by classical condensation reactions which were further converted into the corresponding thienyl- and pyridyl-substituted polydentate lambda(3)-phosphinines by reaction with P(SiMe(3))(3). Further chemical modification of these phosphorus heterocycles with Hg(OAc)(2) in the presence of methanol resulted in the formation of lambda(5)-phosphinines. The photophysical properties of a selected series of thienyl- and pyridyl-functionalized pyrylium salts, lambda(3)- and lambda(5)-phosphinines, were investigated and the results compared and supported by theoretical calculations on the DFT level. Significant fluorescence was observed for the pyrylium salts and lambda(5)-phosphinines. In contrast, the heteroaromatic substituted lambda(3)-phosphinines show very little emission which is consistent with the low oscillator strength predicted by DFT calculations for this pi-->pi* transition. Furthermore, all three classes of compounds show readily observable phosphorescence in solution, which was determined by time-gated detection at low temperature. 相似文献
6.
7.
8.
Dorothee Wistuba 《Journal of chromatography. A》2010,1217(7):941-952
Chiral-modified silica-based monoliths have become well-established stationary phases for both high performance liquid chromatography (HPLC) and capillary electrochromatography (CEC). The silica-based monoliths were fabricated either in situ in the capillaries for nano-HPLC and CEC or in a mould for “conventional” HPLC. The present review summarizes the chiral modification of silica monoliths and the recent development in the field of enantioselective separations by nano-HPLC and CEC. 相似文献
9.
Chemical strategies for iron acquisition in plants 总被引:3,自引:0,他引:3
Staiger D 《Angewandte Chemie (International ed. in English)》2002,41(13):2259-2264
Iron is an essential element for plant nutrition. Although iron is the fourth most abundant element (3 %) of the earth's crust, it is not readily available because of its low solubility. Therefore, plants need an active mechanism to extract iron from the soil. They have evolved several chemical strategies to acquire iron ions and the physiology of these mechanisms has been known for a long time. Only recently, the use of molecular genetic approaches has led to a biochemical and molecular characterization of the players involved, thus providing an entry to the manipulation of iron uptake in plants. 相似文献
10.