全文获取类型
收费全文 | 164篇 |
免费 | 3篇 |
专业分类
化学 | 119篇 |
晶体学 | 1篇 |
数学 | 7篇 |
物理学 | 40篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2019年 | 2篇 |
2017年 | 5篇 |
2015年 | 3篇 |
2014年 | 8篇 |
2013年 | 6篇 |
2012年 | 8篇 |
2011年 | 4篇 |
2010年 | 7篇 |
2009年 | 7篇 |
2008年 | 7篇 |
2007年 | 9篇 |
2006年 | 12篇 |
2005年 | 12篇 |
2004年 | 11篇 |
2003年 | 4篇 |
2002年 | 9篇 |
2001年 | 10篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1956年 | 1篇 |
1939年 | 1篇 |
1930年 | 1篇 |
排序方式: 共有167条查询结果,搜索用时 26 毫秒
21.
Dr. Matthias C. Witschel Dr. H. Wolfgang Höffken Michael Seet Dr. Liliana Parra Thomas Mietzner Frank Thater Dr. Ricarda Niggeweg Dr. Franz Röhl Dr. Boris Illarionov Dr. Felix Rohdich Dr. Johannes Kaiser Prof. Dr. Markus Fischer Prof. Dr. Adelbert Bacher Prof. Dr. François Diederich 《Angewandte Chemie (International ed. in English)》2011,50(34):7931-7935
22.
H. Voit M. Hamm K.G. Nair C. Towsley A.D. Bacher K. Nagatani F. Siller 《Physics letters. [Part B]》1975,58(2):152-154
The reactions 10B+12C, 14N+16O leading to various final states in the isobaric mass systems 11, 13 and 15, respectively, have been investigated experimentally. These measurements provide a number of applications for the extended Barshay-Temmer theorem. 相似文献
23.
24.
J.R. Shepard R.E. Anderson J.J. Kraushaar R.A. Ristinen J.R. Comfort N.S.P. King A. Bacher W.W. Jacobs 《Nuclear Physics A》1979,322(1):92-108
Angular distributions have been measured for the low-lying levels of the residual nuclei for the 12C, 54Fe and 208Pb(p, t) reactions at Ep = 80 MeV. The shapes of these angular distributions are generally well reproduced by the zero-range distorted-wave Born approximation (DWBA). Enhancement factors extracted from the data show that the DWBA predicts relative strengths consistent with those observed at lower bombarding energies. However, the overall empirical DWBA normalization at Ep = 80 MeV is observed to be () of that required at 40 MeV for 208Pb (54Fe). 相似文献
25.
Bakhodir S. Okhundedaev Markus Bacher Rimma F. Mukhamatkhanova Ildar J. Shamyanov Gokhan Zengin Stefan Böhmdorfer 《Natural product research》2019,33(15):2169-2175
A new flavone glucoside, 4′,5-dihydroxy-3′,5′,6-trimethoxyflavone-7-O-β-D-glucoside was obtained from aerial parts of Artemisia juncea, together with the known flavone eupatilin (5,7-dihydroxy-3′,4′,6-trimethoxyflavone). The compounds were comprehensively analytically characterized by IR, UV, NMR and HR-MS, and their chemical structures ascertained. The EtOAc fraction of A. juncea showed the strongest DPPH radical scavenging ability as well as reducing power (in CUPRAC and FRAP assays) and phosphomolybdenum activity. This fraction also exhibited the strongest inhibitory effects on tyrosinase. Additionally, the best antidiabetic effects were observed for eupatilin and the CHCl3 fraction. 相似文献
26.
Hirsch AK Alphey MS Lauw S Seet M Barandun L Eisenreich W Rohdich F Hunter WN Bacher A Diederich F 《Organic & biomolecular chemistry》2008,6(15):2719-2730
Enzymes of the non-mevalonate pathway for isoprenoid biosynthesis are therapeutic targets for the treatment of important infectious diseases. Whereas this pathway is absent in humans, it is used by plants, many eubacteria and apicomplexan protozoa, including major human pathogens such as Plasmodium falciparum and Mycobacterium tuberculosis. Herein, we report on the design, preparation and biological evaluation of a new series of ligands for IspE protein, a kinase from this pathway. These inhibitors were developed for the inhibition of IspE from Escherichia coli, using structure-based design approaches. Structure-activity relationships (SARs) and a co-crystal structure of Aquifex aeolicus IspE bound to a representative inhibitor validate the proposed binding mode. The crystal structure shows that the ligand binds in the substrate-rather than the adenosine 5'-triphosphate (ATP)-binding pocket. As predicted, a cyclopropyl substituent occupies a small cavity not used by the substrate. The optimal volume occupancy of this cavity is explored in detail. In the co-crystal structure, a diphosphate anion binds to the Gly-rich loop, which normally accepts the triphosphate moiety of ATP. This structure provides useful insights for future structure-based developments of inhibitors for the parasite enzymes. 相似文献
27.
28.
Zhang Y Jin G Illarionov B Bacher A Fischer M Cushman M 《The Journal of organic chemistry》2007,72(19):7176-7184
Lumazine synthase catalyzes the penultimate step in the biosynthesis of riboflavin. A homologous series of three pyrazolopyrimidine analogues of a hypothetical intermediate in the lumazine synthase-catalyzed reaction were synthesized and evaluated as lumazine synthase inhibitors. The key steps of the synthesis were C-5 deprotonation of 4-chloro-2,6-dimethoxypyrimidine, acylation of the resulting anion, and conversion of the product to a pyrazolopyrimidine with hydrazine. Alkylation of the pyrazolopyrimidine with a substituted ribityl iodide and deprotection of the ribityl chain afforded the final set of three products. All three compounds were extremely potent inhibitors of the lumazine synthases of Mycobacterium tuberculosis, Magnaporthe grisea, Candida albicans, and Schizosaccharomyces pombe lumazine synthase, with inhibition constants in the low nanomolar to subnanomolar range. Molecular modeling of one of the homologues bound to Mycobacterium tuberculosis lumazine synthase suggests that both the hypothetical intermediate in the lumazine synthase-catalyzed reaction pathway and the metabolically stable analogues bind similarly. 相似文献
29.
Talukdar A Illarionov B Bacher A Fischer M Cushman M 《The Journal of organic chemistry》2007,72(19):7167-7175
Lumazine synthase and riboflavin synthase catalyze the last two steps in the biosynthesis of riboflavin. To obtain structural and mechanistic probes of these two enzymes, as well as inhibitors of potential value as antibiotics, a sulfur analogue of the pyrimidine substrate of the lumazine synthase-catalyzed reaction and product of the riboflavin synthase-catalyzed reaction was designed. Facile syntheses of the S-nucleoside 5-amino-6-(D-ribitylthio)pyrimidine-2,4(1H,3H)-dione hydrochloride (15) and its nitro precursor 5-nitro-6-(D-ribitylthio)pyrimidine-2,4(1H,3H)-dione (14) are described. These compounds were tested against lumazine synthase and riboflavin synthase obtained from a variety of microorganisms. Compounds 14 and 15 were found to be inhibitors of both riboflavin synthase and lumazine synthase. Compound 14 is an inhibitor of Bacillus subtilis lumazine synthase (Ki 26 microM), Schizosaccharomyces pombe lumazine synthase (Ki 2.0 microM), Mycobacterium tuberculosis lumazine synthase (Ki 11 microM), Escherichia coli riboflavin synthase (Ki 2.7 microM), and Mycobacterium tuberculosis riboflavin synthase (Ki 0.56 muM), while compound 15 is an inhibitor of B. subtilis lumazine synthase (Ki 2.6 microM), S. pombe lumazine synthase (Ki 0.16 microM), M. tuberculosis lumazine synthase (Ki 31 microM), E. coli riboflavin synthase (Ki 47 microM), and M. tuberculosis riboflavin synthase (Ki 2.5 microM). 相似文献
30.
Feil S Głuch K Bacher A Matt-Leubner S Böhme DK Scheier P Märk TD 《The Journal of chemical physics》2006,124(21):214307
Using a Nier-type electron impact ion source in combination with a double focusing two sector field mass spectrometer, partial cross sections for electron impact ionization of acetylene are measured for electron energies up to 1000 eV. Discrimination factors for ions are determined using the deflection field method in combination with a three-dimensional ion trajectory simulation of ions produced in the ion source. Analysis of the ion yield curves obtained by scanning the deflectors allows the assignment of ions with the same mass-to-charge ratio to specific production channels on the basis of their different kinetic energy distributions. This analysis also allows to determine, besides kinetic energy distributions of fragment ions, partial cross sections differential in kinetic energy. Moreover a charge separation reaction, the Coulomb explosion of the doubly charged parent ions C2H2++ into the fragment ions C2H+ and H+, is investigated and its mean kinetic energy release (KER=3.88 eV) is deduced. 相似文献