全文获取类型
收费全文 | 1639篇 |
免费 | 62篇 |
国内免费 | 5篇 |
专业分类
化学 | 1020篇 |
晶体学 | 10篇 |
力学 | 44篇 |
数学 | 190篇 |
物理学 | 442篇 |
出版年
2024年 | 1篇 |
2023年 | 15篇 |
2022年 | 36篇 |
2021年 | 58篇 |
2020年 | 53篇 |
2019年 | 64篇 |
2018年 | 48篇 |
2017年 | 44篇 |
2016年 | 82篇 |
2015年 | 70篇 |
2014年 | 91篇 |
2013年 | 124篇 |
2012年 | 115篇 |
2011年 | 131篇 |
2010年 | 87篇 |
2009年 | 80篇 |
2008年 | 120篇 |
2007年 | 91篇 |
2006年 | 92篇 |
2005年 | 75篇 |
2004年 | 43篇 |
2003年 | 16篇 |
2002年 | 29篇 |
2001年 | 20篇 |
2000年 | 18篇 |
1999年 | 12篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 16篇 |
1995年 | 14篇 |
1994年 | 11篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 10篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1972年 | 1篇 |
1937年 | 1篇 |
排序方式: 共有1706条查询结果,搜索用时 62 毫秒
161.
162.
Dr. Tiago Rodrigues Nadine Hauser Daniel Reker Dr. Michael Reutlinger Tiffany Wunderlin Dr. Jacques Hamon Dr. Guido Koch Prof. Dr. Gisbert Schneider 《Angewandte Chemie (International ed. in English)》2015,54(5):1551-1555
We report a multi‐objective de novo design study driven by synthetic tractability and aimed at the prioritization of computer‐generated 5‐HT2B receptor ligands with accurately predicted target‐binding affinities. Relying on quantitative bioactivity models we designed and synthesized structurally novel, selective, nanomolar, and ligand‐efficient 5‐HT2B modulators with sustained cell‐based effects. Our results suggest that seamless amalgamation of computational activity prediction and molecular design with microfluidics‐assisted synthesis enables the swift generation of small molecules with the desired polypharmacology. 相似文献
163.
164.
165.
Frontispiece: Surface Segregated AgAu Tadpole‐Shaped Nanoparticles Synthesized Via a Single Step Combined Galvanic and Citrate Reduction Reaction
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)
166.
167.
Thayana da C. Alves Mariele R. S. Gonçalves Francyne C. S. Correia Virgínia C. da Silva Paulo T. de Sousa Jr. Mário G. de Carvalho Raimundo Braz‐Filho Evandro L. Dall'Oglio 《Helvetica chimica acta》2014,97(11):1469-1474
From the hexane and MeOH extracts of Annona coriacea Mart . (Annonaceae) seeds, two novel acetogenins, coriapentocins A and B ( 1 and 2 , resp.) were isolated. The known acetogenin bullacin ( 3 ) was also isolated from the hexane extract. The structures of compounds 1 – 3 were elucidated by NMR and MS analysis, and relative configurations were established by comparison with literature data. 相似文献
168.
Xerardo García-Mera José E. Rodríguez-Borges M. Luísa C. ValeMaria J. Alves 《Tetrahedron》2011,67(37):7162-7172
The cycloaddition between protonated glyoxylate imines possessing two chiral auxiliaries, N-(S)- or N-(R)-1-phenylethyl and (−)-8-phenylmenthyl or (+)-8-phenylneomenthyl, and cyclopentadiene is described. The absolute configuration of all adducts formed was unequivocally assigned through NMR, specific optical rotation, and X-ray data of appropriated derivatives. Experimental results confirm the highly exo-selectivity for these aza-Diels-Alder reactions, single adducts being obtained from combinations of (8PM)-(R-PEA) and (8PNM)-(S-PEA). 相似文献
169.
Sofia Nikolaou Sérgio Hiroshi Toma Vagner Roberto de Souza Juliano B. Alves Koiti Araki Henrique Eisi Toma 《Transition Metal Chemistry》2011,36(7):775-783
The triruthenium carboxylate cluster [Ru3O(OAc)6(py)2(bpp)]+ (OAc = acetate) containing the bridging 1,3-bis(4-pyridyl)propane (bpp) ligand, and its dimeric species [{Ru3O(OAc)6(py2)}2(μ-bpp)]2+ were synthesized in order to investigate their inclusion compounds with β-cyclodextrin (β-CD). Characterization of the complexes
was carried out based on spectroscopic, electrochemical and spectroelectrochemical techniques, while the formation of inclusion
complexes was evaluated using 1H NMR/NOESY spectroscopy. Since bpp is a flexible ligand, a DFT study was carried out in order to characterize its conformational
isomers and their possible role in the host–guest chemistry with β-CD. Instead of observing the formation of inclusion compounds
with different stoichiometries, we observed the formation of 1:1 bpp/β-CD compounds in which the bpp ligand assumes different
conformations. The assembly of polymetallic rotaxane species was successfully demonstrated by monitoring the 1H NMR spectra of the monomeric cluster species in the presence of aquapentacyanoferrate(II) ions and β-CD. 相似文献
170.
Martins GV Mano JF Alves NM 《Langmuir : the ACS journal of surfaces and colloids》2011,27(13):8415-8423
In this paper, we describe the construction and characteristics of thermoresponsive, thin nanostructured films prepared by layer-by-layer sequential assembly of chitosan-graft-NIPAAm and alginate. FTIR and (1)H NMR spectra have confirmed the introduction of NIPAAm moieties onto the chitosan backbone. The LCST of the synthesized copolymer was found to be around 31-33 °C. The formation of the polyelectrolyte multilayers containing the copolymer and alginate was followed in situ by quartz crystal microbalance with dissipation monitoring technique and ex situ by UV-vis measurements. Our results revealed the linear increase of the multilayer film growth and the influence of the presence of salt. Moreover, AFM analysis has confirmed that PNIPAAm is able to reconform upon temperature swaps even when combined with other layers in a polyelectrolyte multilayer, demonstrating that the nanoassemblies are thermoresponsive. Preliminary results showed that, upon reducing culture temperature below PNIPAAm LCST, a gradual detachment of cell sheets from these PNIPAAm-based coatings has occurred. 相似文献