全文获取类型
收费全文 | 641篇 |
免费 | 18篇 |
国内免费 | 1篇 |
专业分类
化学 | 422篇 |
晶体学 | 10篇 |
力学 | 26篇 |
数学 | 125篇 |
物理学 | 77篇 |
出版年
2022年 | 8篇 |
2021年 | 15篇 |
2020年 | 8篇 |
2019年 | 9篇 |
2018年 | 4篇 |
2017年 | 8篇 |
2016年 | 16篇 |
2015年 | 13篇 |
2014年 | 21篇 |
2013年 | 33篇 |
2012年 | 30篇 |
2011年 | 34篇 |
2010年 | 18篇 |
2009年 | 23篇 |
2008年 | 39篇 |
2007年 | 40篇 |
2006年 | 23篇 |
2005年 | 20篇 |
2004年 | 32篇 |
2003年 | 18篇 |
2002年 | 22篇 |
2001年 | 15篇 |
2000年 | 11篇 |
1999年 | 6篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 9篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 3篇 |
1987年 | 9篇 |
1986年 | 6篇 |
1985年 | 11篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 12篇 |
1981年 | 8篇 |
1980年 | 9篇 |
1979年 | 8篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 11篇 |
1974年 | 5篇 |
1973年 | 9篇 |
排序方式: 共有660条查询结果,搜索用时 62 毫秒
71.
Marino Vega‐Vazquez Juan Carlos Cobas Manuel Martin‐Pastor 《Magnetic resonance in chemistry : MRC》2010,48(10):749-752
A parallel localized spectroscopy (PALSY) method is presented to speed up the acquisition of multidimensional NMR (nD) spectra. The sample is virtually divided into a discrete number of nonoverlapping slices that relax independently during consecutive scans of the experiment, affording a substantial reduction in the interscan relaxation delay and the total experiment time. PALSY was tested for the acquisition of three experiments 2D COSY, 2D DQF‐COSY and 2D TQF‐COSY in parallel, affording a time‐saving factor of 3–4. Some unique advantages are that the achievable resolution in any dimension is not compromised in any way: it uses conventional NMR data processing, it is not prone to generate spectral artifacts, and once calibrated, it can be used routinely with these and other combinations of NMR spectra. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
72.
73.
74.
75.
Simone Zanella Dr. Michele Mingozzi Alberto Dal Corso Dr. Roberto Fanelli Dr. Daniela Arosio Prof. Dr. Marco Cosentino Dr. Laura Schembri Dr. Franca Marino Dr. Marta De Zotti Prof. Dr. Fernando Formaggio Dr. Luca Pignataro Prof. Dr. Laura Belvisi Prof. Dr. Umberto Piarulli Prof. Dr. Cesare Gennari 《ChemistryOpen》2015,4(5):633-641
A dual-action ligand targeting both integrin αVβ3 and vascular endothelial growth factor receptors (VEGFRs), was synthesized via conjugation of a cyclic peptidomimetic αVβ3 Arg-Gly-Asp (RGD) ligand with a decapentapeptide. The latter was obtained from a known VEGFR antagonist by acetylation at the Lys13 side chain. Functionalization of the precursor ligands was carried out in solution and in the solid phase, affording two fragments: an alkyne VEGFR ligand and the azide integrin αVβ3 ligand, which were conjugated by click chemistry. Circular dichroism studies confirmed that both the RGD and VEGFR ligand portions of the dual-action compound substantially adopt the biologically active conformation. In vitro binding assays on isolated integrin αVβ3 and VEGFR-1 showed that the dual-action conjugate retains a good level of affinity for both its target receptors, although with one order of magnitude (10/20 times) decrease in potency. The dual-action ligand strongly inhibited the VEGF-induced morphogenesis in Human Umbilical Vein Endothelial Cells (HUVECs). Remarkably, its efficiency in preventing the formation of new blood vessels was similar to that of the original individual ligands, despite the worse affinity towards integrin αVβ3 and VEGFR-1. 相似文献
76.
Mechanism of Thyroxine Deiodination by Naphthyl‐Based Iodothyronine Deiodinase Mimics and the Halogen Bonding Role: A DFT Investigation
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Mariagrazia Fortino Prof. Dr. Tiziana Marino Prof. Nino Russo Prof. Dr. Emilia Sicilia 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(23):8554-8560
This paper deals with a systematic density functional theory (DFT) study aiming to unravel the mechanism of the thyroxine (T4) conversion into 3,3′,5‐triiodothyronine (rT3) by using different bio‐inspired naphthyl‐based models, which are able to reproduce the catalytic functions of the type‐3 deiodinase ID‐3. Such naphthalenes, having two selenols, two thiols, and a selenol–thiol pair in peri positions, which were previously synthesized and tested in their deiodinase activity, are able to remove iodine selectively from the inner ring of T4 to produce rT3. Calculations were performed including also an imidazole ring that, mimicking the role of the His residue, plays an essential role deprotonating the selenol/thiol moiety. For all the used complexes, the calculated potential energy surfaces show that the reaction proceeds via an intermediate, characterized by the presence of a X?I?C (X=Se, S) halogen bond, whose transformation into a subsequent intermediate in which the C?I bond is definitively cleaved and the incipient X?I bond is formed represents the rate‐determining step of the whole process. The calculated trend in the barrier heights of the corresponding transition states allows us to rationalize the experimentally observed superior deiodinase activity of the naphthyl‐based compound with two selenol groups. The role of the peri interactions between chalcogen atoms appears to be less prominent in determining the deiodination activity. 相似文献
77.
78.
79.
Stefania Corsaro Ioannis Kyriakou Daniele Marazzina Zelda Marino 《European Journal of Operational Research》2019,272(3):1082-1095
In this paper, we present a transform-based algorithm for pricing discretely monitored arithmetic Asian options with remarkable accuracy in a general stochastic volatility framework, including affine models and time-changed Lévy processes. The accuracy is justified both theoretically and experimentally. In addition, to speed up the valuation process, we employ high-performance computing technologies. More specifically, we develop a parallel option pricing system that can be easily reproduced on parallel computers, also realized as a cluster of personal computers. Numerical results showing the accuracy, speed and efficiency of the procedure are reported in the paper. 相似文献
80.
Two infinite families of two–character sets in PG(5,q) arising from the Veronese surface of PG(5,q) are constructed. 相似文献