全文获取类型
收费全文 | 691篇 |
免费 | 33篇 |
国内免费 | 1篇 |
专业分类
化学 | 536篇 |
晶体学 | 2篇 |
力学 | 7篇 |
数学 | 99篇 |
物理学 | 81篇 |
出版年
2023年 | 6篇 |
2022年 | 8篇 |
2021年 | 15篇 |
2020年 | 13篇 |
2019年 | 12篇 |
2018年 | 9篇 |
2017年 | 11篇 |
2016年 | 36篇 |
2015年 | 30篇 |
2014年 | 27篇 |
2013年 | 42篇 |
2012年 | 62篇 |
2011年 | 59篇 |
2010年 | 52篇 |
2009年 | 55篇 |
2008年 | 57篇 |
2007年 | 33篇 |
2006年 | 44篇 |
2005年 | 30篇 |
2004年 | 24篇 |
2003年 | 17篇 |
2002年 | 17篇 |
2001年 | 2篇 |
2000年 | 8篇 |
1999年 | 10篇 |
1998年 | 8篇 |
1997年 | 8篇 |
1996年 | 6篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 9篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1984年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有725条查询结果,搜索用时 0 毫秒
91.
92.
Silvia Valera Dr. Katrin Ackermann Dr. Christos Pliotas Dr. Hexian Huang Prof. James H. Naismith Dr. Bela E. Bode 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(14):4700-4703
Pulse electron paramagnetic resonance (EPR) is gaining increasing importance in structural biology. The PELDOR (pulsed electron–electron double resonance) method allows extracting distance information on the nanometer scale. Here, we demonstrate the efficient extraction of distances from multimeric systems such as membrane‐embedded ion channels where data analysis is commonly hindered by multi‐spin effects. 相似文献
93.
94.
Synthesis and Isolation of the Titanium–Scandium Endohedral Fullerenes—Sc2TiC@Ih‐C80, Sc2TiC@D5h‐C80 and Sc2TiC2@Ih‐C80: Metal Size Tuning of the TiIV/TiIII Redox Potentials 下载免费PDF全文
Katrin Junghans Dr. Kamran B. Ghiassi Nataliya A. Samoylova Qingming Deng Marco Rosenkranz Prof. Marilyn M. Olmstead Prof. Alan L. Balch Dr. Alexey A. Popov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(37):13098-13107
The formation of endohedral metallofullerenes (EMFs) in an electric arc is reported for the mixed‐metal Sc–Ti system utilizing methane as a reactive gas. Comparison of these results with those from the Sc/CH4 and Ti/CH4 systems as well as syntheses without methane revealed a strong mutual influence of all key components on the product distribution. Whereas a methane atmosphere alone suppresses the formation of empty cage fullerenes, the Ti/CH4 system forms mainly empty cage fullerenes. In contrast, the main fullerene products in the Sc/CH4 system are Sc4C2@C80 (the most abundant EMF from this synthesis), Sc3C2@C80, isomers of Sc2C2@C82, and the family Sc2C2 n (2 n=74, 76, 82, 86, 90, etc.), as well as Sc3CH@C80. The Sc–Ti/CH4 system produces the mixed‐metal Sc2TiC@C2 n (2 n=68, 78, 80) and Sc2TiC2@C2 n (2 n=80) clusterfullerene families. The molecular structures of the new, transition‐metal‐containing endohedral fullerenes, Sc2TiC@Ih‐C80, Sc2TiC@D5h‐C80, and Sc2TiC2@Ih‐C80, were characterized by NMR spectroscopy. The structure of Sc2TiC@Ih‐C80 was also determined by single‐crystal X‐ray diffraction, which demonstrated the presence of a short Ti=C double bond. Both Sc2TiC‐ and Sc2TiC2‐containing clusterfullerenes have Ti‐localized LUMOs. Encapsulation of the redox‐active Ti ion inside the fullerene cage enables analysis of the cluster–cage strain in the endohedral fullerenes through electrochemical measurements. 相似文献
95.
Franziska Doll Annette Buntz Anne‐Katrin Späte Verena F. Schart Alexander Timper Waldemar Schrimpf Prof. Dr. Christof R. Hauck Prof. Dr. Andreas Zumbusch Prof. Dr. Valentin Wittmann 《Angewandte Chemie (International ed. in English)》2016,55(6):2262-2266
Protein glycosylation is a ubiquitous post‐translational modification that is involved in the regulation of many aspects of protein function. In order to uncover the biological roles of this modification, imaging the glycosylation state of specific proteins within living cells would be of fundamental importance. To date, however, this has not been achieved. Herein, we demonstrate protein‐specific detection of the glycosylation of the intracellular proteins OGT, Foxo1, p53, and Akt1 in living cells. Our generally applicable approach relies on Diels–Alder chemistry to fluorescently label intracellular carbohydrates through metabolic engineering. The target proteins are tagged with enhanced green fluorescent protein (EGFP). Förster resonance energy transfer (FRET) between the EGFP and the glycan‐anchored fluorophore is detected with high contrast even in presence of a large excess of acceptor fluorophores by fluorescence lifetime imaging microscopy (FLIM). 相似文献
96.
97.
Magistrato A Ruggerone P Spiegel K Carloni P Reedijk J 《The journal of physical chemistry. B》2006,110(8):3604-3613
Dinuclear Pt-containing compounds might be used to overcome the intrinsic and acquired cell resistance of widely used anticancer drugs such as cisplatin. Recently, the complexes [[cis-Pt(NH3)2]2(mu-OH)(mu-pz)](NO3)2 (with pz = pyrazolate) (1), [[cis-Pt(NH3)2]2(mu-OH)(mu-1,2,3-ta-N(1),N(2))](NO3)2 (with ta = 1,2,3-triazolate) (2), and the binding of 1 to d(CpTpCpTpG*pG*pTpCpTpCp) have been characterized. Here we provide the structural and electronic properties of the free drugs, of the intermediates of binding to guanine bases, and of the products, by performing DFT calculations. Our results show that in 2 an isomerization of the Pt-coordination sphere from N(2) to N(3) of the triazolate unit determines a thermodynamic stabilization of approximately 20 kcal/mol as a consequence of the formation of an allylic structure. In addition, hybrid quantum-classical molecular dynamics simulations of 1 and 2 DNA adducts have shed light on the structural distortions that the drugs induce to the DNA duplex. Our calculations show that the rise and the tilt of the two adjacent guanines are identical in the presence of 1 and 2, but they markedly increase when 2 binds in the N(1),N(3) fashion. In addition, the drugs do not provoke any kink upon binding to the double-stranded DNA, suggesting that they may act with a mechanism different than that of cisplatin. The accuracy of our calculations is established by a comparison with the NMR data for the corresponding complex with 1. 相似文献
98.
The laccase catalyzed oxidative dimerization of salicylic esters, a rare example of a laccase-catalyzed carbon-carbon bond formation, was studied. This reaction allows the use of air as stoichiometric oxidant and proceeds in aqueous solution. The preparative scope and the mechanism of the method, which provides a new and convenient access to functionalized biaryls under mild conditions, were investigated. 相似文献
99.
Katrin Schwikal Thomas Heinze Anna Ebringerová Katrin Petzold 《Macromolecular Symposia》2005,232(1):49-56
Xylan from birch wood was characterized regarding both the supramolecular structure (X-ray, CP/MAS 13C-NMR) and the sugar composition. The reaction of the birch wood xylan with 2,3-epoxypropyltrimethylammonium chloride in 1,2-dimethoxyethane as slurry medium yields water-soluble, cationic 2-hydroxypropyltrimethylammonium xylan derivatives with high degree of substitution (DS). The DS values up to 1.6 can be controlled by adjusting the molar ratio in a one step synthesis. The structure of the cationic xylan derivatives was confirmed by means of DEPT(135) NMR spectroscopy. Film forming properties of cationic xylan derivatives were investigated with SEM measurements. 相似文献
100.