全文获取类型
收费全文 | 380篇 |
免费 | 5篇 |
国内免费 | 1篇 |
专业分类
化学 | 256篇 |
晶体学 | 3篇 |
力学 | 2篇 |
数学 | 43篇 |
物理学 | 82篇 |
出版年
2020年 | 4篇 |
2018年 | 3篇 |
2016年 | 3篇 |
2015年 | 5篇 |
2014年 | 5篇 |
2013年 | 51篇 |
2012年 | 19篇 |
2011年 | 9篇 |
2010年 | 9篇 |
2009年 | 15篇 |
2008年 | 15篇 |
2007年 | 18篇 |
2006年 | 5篇 |
2005年 | 14篇 |
2004年 | 11篇 |
2003年 | 8篇 |
2002年 | 13篇 |
2001年 | 6篇 |
2000年 | 12篇 |
1999年 | 8篇 |
1998年 | 7篇 |
1997年 | 7篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1986年 | 3篇 |
1985年 | 9篇 |
1984年 | 5篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1977年 | 3篇 |
1976年 | 6篇 |
1974年 | 4篇 |
1964年 | 2篇 |
1963年 | 2篇 |
1937年 | 2篇 |
1936年 | 2篇 |
1934年 | 2篇 |
1933年 | 3篇 |
1930年 | 3篇 |
1910年 | 2篇 |
1908年 | 2篇 |
1907年 | 4篇 |
1905年 | 3篇 |
1903年 | 3篇 |
排序方式: 共有386条查询结果,搜索用时 15 毫秒
11.
Peter G. Van Ysacker Henri M. Snijders Hans-Gerd M. Janssen Carel A. Cramers 《Journal of separation science》1998,21(9):491-497
The use of hot splitless, cold splitless, and on-column injections for trace analysis in narrow-bore capillary GC is evaluated. Despite the low flow rates for the columns used, the required splitless times for splitless injections can be surprisingly short if liners with a small inside diameter are used. On-column injection can be applied by using an appropriate normal-bore precolumn coupled to the narrow-bore analytical column using a specially designed low dead volume column connector. The effects of the experimental conditions such as sample volume, injection temperature, and initial oven temperature on peak focusing and the discrimination and degradation behavior of the analytes are discussed. The possibilities to obtain sensitive and fast separations are illustrated by various applications. 相似文献
12.
Asymmetric trans-bioreduction of activated alkenes by KYE1 from Kluyveromyces lactis and Yers-ER from Yersinia bercovieri, two ene-reductases from the Old Yellow Enzyme family, showed a broad substrate spectrum with a moderate to excellent degree of stereoselectivity. Both substrate- and enzyme-based stereocontrols were observed to furnish opposite stereoisomeric products. The effects of organic solvents on enzyme activity and stereoselectivity were outlined in this study, where two-phase systems hexane and toluene are shown to sustain bioreduction efficiency even at high organic solvent content. 相似文献
13.
Mateja Pogorevc Ulrike T. Strauss Marianne Hayn Kurt Faber 《Monatshefte für Chemie / Chemical Monthly》2000,220(2):639-644
Biocatalytic resolution of the tertiary terpene alcohol (±)-linalool was accomplished via hydrolysis of its corresponding acetate ester using two highly enantiospecific enzymes (E > 100). The latter were identified in a crude cell-free extract of Rhodococcus ruber DSM 43338 and could be separated by (partial) protein purification. Since they showed opposite enantiopreference, they were
termed (R)- and (S)-linalyl acetate hydrolase (LAH). The activity and selectivity of the enzyme preparations was markedly dependent on the fermentation
conditions. 相似文献
14.
The biosynthesis of cyclic terpenoids and polyethers involves enzyme-initiated cascade reactions for ring formation. While the former are obtained by electrophilic cascades through carbenium ions as intermediates, cyclic polyethers are formed by nucleophilic cascade reactions of (poly)epoxide precursors. These mechanistically complementary pathways follow common principles via (i) triggering of the cascade by forming a reactive intermediate ('initiation'), (ii) sequential 'proliferation' of the cyclization and finally (iii) 'termination' of the cascade. As analyzed in this concept paper, the multiplicity of precursors, combined with various initiation and termination routes and kinetically favored or disfavored cyclization modes accounts for the enormous diversity in cyclic terpenoid and polyether scaffolds. Although the essential role of enzymes in the triggering of these cascades is reasonably well understood, remarkably little is known about their influence in proliferation reactions, especially those implying kinetically disfavored (anti-Markovnikov and anti-Baldwin) routes. Mechanistic analysis of enzymatic cascade reactions provides biomimetic strategies for natural product synthesis. 相似文献
15.
16.
Carel J. van Oss 《Separation & Purification Reviews》2013,42(1):83-85
ULTRAFILTRATION MEMBRANES AND APPLICATIONS Anthony R. Cooper, Ed. Plenum Press, New York, 1980; hardbound, 707 pages, $75.00 POLYMERIC SEPARATION MEDIA Anthony R. Cooper, Ed. Plenum Press, New York, 1982; hardbound 276 pages, $39.50 相似文献
17.
18.
19.
20.
Carel J. van Oss 《Journal of Dispersion Science and Technology》2013,34(5-6):550-551