全文获取类型
收费全文 | 1195篇 |
免费 | 59篇 |
国内免费 | 2篇 |
专业分类
化学 | 835篇 |
晶体学 | 43篇 |
力学 | 45篇 |
数学 | 136篇 |
物理学 | 197篇 |
出版年
2023年 | 10篇 |
2022年 | 6篇 |
2021年 | 12篇 |
2020年 | 24篇 |
2019年 | 23篇 |
2018年 | 20篇 |
2017年 | 17篇 |
2016年 | 33篇 |
2015年 | 35篇 |
2014年 | 41篇 |
2013年 | 71篇 |
2012年 | 72篇 |
2011年 | 76篇 |
2010年 | 52篇 |
2009年 | 58篇 |
2008年 | 92篇 |
2007年 | 79篇 |
2006年 | 85篇 |
2005年 | 56篇 |
2004年 | 60篇 |
2003年 | 47篇 |
2002年 | 39篇 |
2001年 | 16篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 5篇 |
1997年 | 12篇 |
1996年 | 12篇 |
1995年 | 10篇 |
1994年 | 11篇 |
1993年 | 12篇 |
1991年 | 11篇 |
1989年 | 7篇 |
1988年 | 10篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 10篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1977年 | 5篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1972年 | 4篇 |
1969年 | 5篇 |
1905年 | 5篇 |
1904年 | 8篇 |
排序方式: 共有1256条查询结果,搜索用时 15 毫秒
1.
Philipp Dabringhaus Marcel Schorpp Dr. Harald Scherer Prof. Dr. Ingo Krossing 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(49):22207-22211
The potential of a dicationic strontium ansa-arene complex for Lewis acid catalysis has been explored. The key to its synthesis was a simple salt metathesis from SrI2 and 2 Ag[Al(ORF)4], giving the base-free strontium-perfluoroalkoxyaluminate Sr[Al(ORF)4]2 (ORF=OC(CF3)3). Addition of an ansa-arene yielded the highly Lewis acidic, dicationic strontium ansa-arene complex. In preliminary experiments, the complex was successfully applied as a catalyst in CO2-reduction to CH4 and a surprisingly controlled isobutylene polymerization reaction. 相似文献
2.
3.
4.
5.
Jiang Tian Liu Hannes Hase Sarah Taylor Ingo Salzmann Pat Forgione 《Angewandte Chemie (International ed. in English)》2020,59(18):7146-7153
A library of symmetrical linear oligothiophene was prepared employing decarboxylative cross‐coupling reaction as the key transformation. Thiophene potassium carboxylate salts were used as cross‐coupling partners without the need of co‐catalyst, base, or additives. This method demonstrates complete chemoselectivity and is a comprehensive greener approach compared to the existing methods. The modularity of this approach is demonstrated with the preparation of discreet oligothiophenes with up to 10 thiophene repeat units. Symmetrical oligothiophenes are prototypical organic semiconductors where their molecular electrical doping as a function of the chain length can be assessed spectroscopically. An oligothiophene critical length for integer charge transfer was observed to be 10 thiophene units, highlighting the potential use of discrete oligothiophenes as doped conduction or injection layers in organic electronics applications. 相似文献
6.
7.
Inside Back Cover: Univalent Gallium Complexes of Simple and ansa‐Arene Ligands: Effects on the Polymerization of Isobutylene (Chem. Eur. J. 1/2015) 下载免费PDF全文
8.
Ferrocenyl‐Coupled N‐Heterocyclic Carbene Complexes of Gold(I): A Successful Approach to Multinuclear Anticancer Drugs 下载免费PDF全文
Dr. Julienne K. Muenzner Dr. Bernhard Biersack Alexander Albrecht Tobias Rehm Dr. Ulrike Lacher Dr. Wolfgang Milius Prof. Dr. Angela Casini Dr. Jing‐Jing Zhang Prof. Dr. Ingo Ott Prof. Dr. Viktor Brabec Olga Stuchlikova Dr. Ion C. Andronache Leonard Kaps Prof. Dr. Dr. Detlef Schuppan Prof. Dr. Rainer Schobert 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(52):18953-18962
Four gold(I) carbene complexes featuring 4‐ferrocenyl‐substituted imidazol‐2‐ylidene ligands were investigated for antiproliferative and antivascular properties. They were active against a panel of seven cancer cell lines, including multidrug‐resistant ones, with low micromolar or nanomolar IC50 (72 h) values, according to their lipophilicity and cellular uptake. The delocalized lipophilic cationic complexes 8 and 10 acted by increasing the reactive oxygen species in two ways: through a genuine ferrocene effect and by inhibiting the thioredoxin reductase. Both complexes gave rise to a reorganization of the F‐actin cytoskeleton in endothelial and melanoma cells, associated with a G1 phase cell cycle arrest and a retarded cell migration. They proved antiangiogenic in tube formation assays with endothelial cells and vascular‐disruptive on real blood vessels in the chorioallantoic membrane of chicken eggs. Biscarbene complex 10 was also tolerated well by mice where it led to a volume reduction of xenograft tumors by up to 80 %. 相似文献
9.
Lars Lauterbach Hongxin Wang Marius Horch Leland B. Gee Yoshitaka Yoda Yoshihito Tanaka Ingo Zebger Oliver Lenz Stephen P. Cramer 《Chemical science》2015,6(2):1055-1060
Hydrogenases are complex metalloenzymes that catalyze the reversible splitting of molecular hydrogen into protons and electrons essentially without overpotential. The NAD+-reducing soluble hydrogenase (SH) from Ralstonia eutropha is capable of H2 conversion even in the presence of usually toxic dioxygen. The molecular details of the underlying reactions are largely unknown, mainly because of limited knowledge of the structure and function of the various metal cofactors present in the enzyme. Here, all iron-containing cofactors of the SH were investigated by 57Fe specific nuclear resonance vibrational spectroscopy (NRVS). Our data provide experimental evidence for one [2Fe2S] center and four [4Fe4S] clusters, which is consistent with the amino acid sequence composition. Only the [2Fe2S] cluster and one of the four [4Fe4S] clusters were reduced upon incubation of the SH with NADH. This finding explains the discrepancy between the large number of FeS clusters and the small amount of FeS cluster-related signals as detected by electron paramagnetic resonance spectroscopic analysis of several NAD+-reducing hydrogenases. For the first time, Fe–CO and Fe–CN modes derived from the [NiFe] active site could be distinguished by NRVS through selective 13C labeling of the CO ligand. This strategy also revealed the molecular coordinates that dominate the individual Fe–CO modes. The present approach explores the complex vibrational signature of the Fe–S clusters and the hydrogenase active site, thereby showing that NRVS represents a powerful tool for the elucidation of complex biocatalysts containing multiple cofactors. 相似文献
10.
Somaiyeh Charoughchi Jiang Tian Liu Melissa Berteau-Rainville Hannes Hase Mohammad S. Askari Shubham Bhagat Pat Forgione Ingo Salzmann 《Angewandte Chemie (International ed. in English)》2023,62(31):e202304964
Molecular p-dopants designed to undergo electron transfer with organic semiconductors are typically planar molecules with high electron affinity. However, their planarity can promote the formation of ground-state charge transfer complexes with the semiconductor host and results in fractional instead of integer charge transfer, which is highly detrimental to doping efficiency. Here, we show this process can be readily overcome by targeted dopant design exploiting steric hindrance. To this end, we synthesize and characterize the remarkably stable p-dopant 2,2′,2′′-(cyclopropane-1,2,3-triylidene)tris(2-(perfluorophenyl)acetonitrile) comprising pendant functional groups that sterically shield its central core while retaining high electron affinity. Finally, we demonstrate it outperforms a planar dopant of identical electron affinity and increases the thin film conductivity by up to an order of magnitude. We believe exploiting steric hindrance represents a promising design strategy towards molecular dopants of enhanced doping efficiency. 相似文献