全文获取类型
收费全文 | 374篇 |
免费 | 31篇 |
国内免费 | 10篇 |
专业分类
化学 | 197篇 |
力学 | 22篇 |
综合类 | 3篇 |
数学 | 81篇 |
物理学 | 112篇 |
出版年
2020年 | 3篇 |
2018年 | 8篇 |
2017年 | 3篇 |
2016年 | 10篇 |
2015年 | 8篇 |
2014年 | 20篇 |
2013年 | 40篇 |
2012年 | 11篇 |
2011年 | 25篇 |
2010年 | 10篇 |
2009年 | 3篇 |
2008年 | 18篇 |
2007年 | 12篇 |
2006年 | 11篇 |
2005年 | 11篇 |
2004年 | 9篇 |
2003年 | 6篇 |
2002年 | 20篇 |
2001年 | 11篇 |
2000年 | 10篇 |
1998年 | 3篇 |
1997年 | 13篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 7篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 8篇 |
1978年 | 4篇 |
1977年 | 8篇 |
1976年 | 6篇 |
1975年 | 6篇 |
1974年 | 3篇 |
1969年 | 2篇 |
1968年 | 3篇 |
1966年 | 2篇 |
1940年 | 2篇 |
1936年 | 2篇 |
1905年 | 2篇 |
1890年 | 2篇 |
排序方式: 共有415条查询结果,搜索用时 93 毫秒
411.
A new machine for conducting continuous flow processes at low temperatures on a laboratory scale is reported. The use of this cryogenic flow reactor has been demonstrated by the preparation of a variety of (hetero)aromatic boronic acids and esters via lithium halogen exchange chemistry. Furthermore, scale-up of the reaction conditions not only demonstrates the application of this device for the preparation of useful building blocks but also combines the ability to process n-butyllithium directly through pump heads attached to the unit. 相似文献
412.
Properties of self-assembled monolayers (SAMs) can be tailored by the curvature of the underlying surface. This is so because on a curved support the density of SAM headgroups is always smaller than that of the surface-attachment sites. This density difference increases with increasing curvature and is most pronounced for SAMs formed on nanoscopic particles. This Perspective describes systems in which nanoscale curvature causes pronounced changes in the pK(a) of acid-presenting SAMs or in the electrochemical potential of redox-active molecules (including supramolecular "switches") attached to nanoparticles. It is suggested that in nanoparticles having regions of different curvature these geometrical differences can translate into site-selective charging; such "patchy" particles could be used as building blocks of pH-sensitive assemblies. 相似文献
413.
Zhang X Hou L Cnossen A Coleman AC Ivashenko O Rudolf P van Wees BJ Browne WR Feringa BL 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(32):8957-8964
Two types of graphene‐based hybrid materials, graphene‐TPP (TPP=tetraphenylporphyrin) and graphene‐PdTPP (PdTPP=palladium tetraphenylporphyrin), were prepared directly from pristine graphene through one‐pot cycloaddition reactions. The hybrid materials were characterized by thermogravimetric analysis (TGA), by TEM, by UV/Vis, FTIR, Raman, and luminescence spectroscopy, and by fluorescence/phosphorescence lifetime measurements. The presence of the covalent linkages between graphene and porphyrin was confirmed by FTIR and Raman spectroscopy and further supported by control experiments. The presence of TPP (or PdTPP) in the hybrid material was demonstrated by UV/Vis spectroscopy, with TGA results indicating that the graphene‐TPP and graphene‐PdTPP hybrid materials contained approximately 18 % TPP and 20 % PdTPP. The quenching of fluorescence (or phosphorescence) and reduced lifetimes suggest excited state energy/electron transfer between graphene and the covalently attached TPP (or PdTPP) molecules. 相似文献
414.
Ahmed HM Coburn N Dini D de Jong JJ Villani C Browne WR Vos JG 《Inorganic chemistry》2011,50(13):5861-5863
Circular dichroism (CD) spectroelectrochemistry is used to determine the extent of singly occupied molecular orbital delocalization in mixed-valence multinuclear complexes, specifically the mixed-valence Ru(II)Ru(III) states of the four diastereoisomers of [(Ru(bpy)(2))(2)(bpt)](3+) [1; bpy = 2,2'-bipyridyl and bpt = 3,5-bis(pyrid-2'-yl)-1,2,4-triazolato anion]. The complex was found to be stable to thermal racemization in the three oxidation states, but photoracemization in the Ru(II)Ru(II) state was observed. 相似文献
415.
We present a scheme for linear optical quantum computation that is highly robust to imperfect single photon sources and inefficient detectors. In particular we show that if the product of the detector efficiency with the source efficiency is greater than 2/3, then efficient linear optical quantum computation is possible. This high threshold is achieved within the cluster state paradigm for quantum computation. 相似文献