全文获取类型
收费全文 | 220篇 |
免费 | 13篇 |
专业分类
化学 | 166篇 |
晶体学 | 9篇 |
力学 | 2篇 |
数学 | 18篇 |
物理学 | 38篇 |
出版年
2023年 | 4篇 |
2022年 | 10篇 |
2021年 | 14篇 |
2020年 | 9篇 |
2019年 | 7篇 |
2018年 | 7篇 |
2016年 | 8篇 |
2015年 | 5篇 |
2014年 | 9篇 |
2013年 | 15篇 |
2012年 | 12篇 |
2011年 | 13篇 |
2010年 | 6篇 |
2009年 | 6篇 |
2008年 | 4篇 |
2007年 | 5篇 |
2006年 | 5篇 |
2005年 | 4篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1982年 | 5篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1969年 | 1篇 |
1967年 | 2篇 |
1966年 | 1篇 |
1965年 | 3篇 |
1964年 | 7篇 |
1963年 | 2篇 |
1962年 | 3篇 |
1938年 | 2篇 |
1927年 | 1篇 |
1925年 | 1篇 |
1899年 | 1篇 |
1898年 | 1篇 |
排序方式: 共有233条查询结果,搜索用时 125 毫秒
61.
Beta-cyclodextrin can act as an efficient inhibitor of the photosensitized dimerization of thymine by para-aminobenzoic acid (PABA) in aqueous solution. This can be explained by considering the formation of an inclusion complex between PABA and beta-cyclodextrin. 相似文献
62.
63.
Abstract A versatile and efficient route to macrocyclic amides via high-pressure synthesis is described. Application of the high-pressure technique allows obtaining the title compounds under ambient conditions. The scope and limitations of this reaction are presented. 相似文献
64.
65.
Daniel T. Gryko Agnieszka Pęcak Wiktor Koźmiński Piotr Piątek Janusz Jurczak 《Supramolecular chemistry》2013,25(2):229-235
Abstract We examined complexing sites of the Pb2+ complex of the macrocyclic lactam 1 using 15N NMR and other spectroscopies and we have found that the amide groups undergo conformational changes to allow the complexation process to proceed via the pyridine nitrogen atom and carbonyl and ethereal oxygen atoms. X-Ray analysis of compound 1 was carried out successfully. Space group I41/a, a=28.332(4)Å, b=28.332(4)Å, c=10.7379(4)Å, Z=16, V=8619.3(18)Å3, Dc=1.197gcm?3, R1=0.0479 (based on 2510 reflections I>2[sgrave](I). It shows presence of intramolecular hydrogen bonds, which are broken during the complexation. Molecules form supramolecular tetragonal assemblies in the crystal, which form channels the walls of which are 7.42 Å apart. 相似文献
66.
Rafał Wysokiński Wiktor Zierkiewicz Mariusz Michalczyk Steve Scheiner 《Chemphyschem》2020,21(11):1119-1125
High-level ab initio calculations show that the MCl3− anions comprising Group 2B M atoms Zn, Cd, and Hg form a stable complex with the CN− anion, despite the like charge of the two ions. The complexation occurs despite a negative π-hole region above the M atom of MCl3−. The dimerization distorts the planar geometry of MCl3− into a pyramidal shape which reduces the negative potential above the M atom, facilitating a close approach of the two anions, with R(M⋅⋅⋅C)∼2 Å, and an overall attractive electrostatic attraction within the dimer. In the gas phase, this dimer is less stable than the pair of separated ions by some 30 kcal/mol. However, the dissociation must surmount an energy barrier of roughly 25 kcal/mol which occurs at an intermolecular distance of 4 Å. In aqueous solution, the dimerization process is exothermic and barrier-free, with a binding energy in the 11–18 kcal/mol range. 相似文献
67.
68.
69.
Mickel J. Hansen Michael M. Lerch Dr. Wiktor Szymanski Prof. Dr. Ben L. Feringa 《Angewandte Chemie (International ed. in English)》2016,55(43):13514-13518
A straightforward synthesis of azobenzenes with bathochromically‐shifted absorption bands is presented. It employs an ortho‐lithiation of aromatic substrates, followed by a coupling reaction with aryldiazonium salts. The products are obtained with good to excellent yields after simple purification. Moreover, with the presented methodology, a structurally diverse panel of different azobenzenes, including unsymmetric tetra‐ortho‐substituted ones, can be readily obtained, which paves the way for future development of red‐light‐addressable azobenzene derivatives for in vivo application. 相似文献
70.
Magdalena Żurowska Przemysław Morawiak Wiktor Piecek Michał Czerwiński Anna Spadło Noureddine Bennis 《Liquid crystals》2016,43(10):1365-1374
New compounds (S)-4?-(1-methylheptyloxycarbonyl)biphenyl-4-yl 4-[3-(2,2,3,3,4,4,5,5,5-nonafluoropentyloxy)prop-1-oxy]benzoates were synthesised and characterised. Their mesomorphic properties were tested by means of polarising optical microscopy and differential scanning calorimetry. The multicomponent antiferroelectric high tilt mixture with long pitch has been also formulated and characterised. The helical pitch of prepared mixture was estimated with selective reflection method. 相似文献