全文获取类型
收费全文 | 186篇 |
免费 | 13篇 |
国内免费 | 8篇 |
专业分类
化学 | 139篇 |
晶体学 | 2篇 |
力学 | 3篇 |
数学 | 27篇 |
物理学 | 36篇 |
出版年
2023年 | 1篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 4篇 |
2018年 | 1篇 |
2017年 | 7篇 |
2016年 | 8篇 |
2015年 | 8篇 |
2014年 | 3篇 |
2013年 | 22篇 |
2012年 | 21篇 |
2011年 | 17篇 |
2010年 | 9篇 |
2009年 | 5篇 |
2008年 | 15篇 |
2007年 | 15篇 |
2006年 | 9篇 |
2005年 | 11篇 |
2004年 | 5篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 1篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
排序方式: 共有207条查询结果,搜索用时 46 毫秒
71.
72.
Marcin Pastorczak Gustavo Dominguez-Espinosa Lidia Okrasa Marek Pyda Marcin Kozanecki Slawomir Kadlubowski Janusz M. Rosiak Jacek Ulanski 《Colloid and polymer science》2014,292(8):1775-1784
Water interacting with a polymer reveals a number of properties very different to bulk water. These interactions lead to the redistribution of hydrogen bonds in water. It results in modification of thermodynamic properties of water and the molecular dynamics of water. That kind of water is particularly well observable at temperatures below the freezing point of water, when the bulk water crystallizes. In this work, we determine the amount of water bound to the polymer and of the so-called pre-melting water in poly(vinyl methyl ether) hydrogels with the use of Raman spectroscopy, dielectric spectroscopy, and calorimetry. This analysis allows us to compare various physical properties of the bulk and the pre-melting water. We also postulate the molecular mechanism responsible for the pre-melting of part of water in poly(vinyl methyl ether) hydrogels. We suggest that above ?60 °C, the first segmental motions of the polymer chain are activated, which trigger the process of the pre-melting. 相似文献
73.
We compute the smooth cohomology (both unrestricted and compactly supported) of the supercharge of an ultraviolet cutoffN=2 supersymmetric Landau-Ginzburg field theory.Supported in part by the National Science Foundation under grant DMS-9206936.Supported in part by the Department of Energy under grant DE-FG02-88ER25065. 相似文献
74.
Slawomir Bugajski 《International Journal of Theoretical Physics》1993,32(3):389-398
The algebraic structure of the set of elementary observables of a delinearized quantal theory is described. As the delinearization procedure provides a kind of classical representation for any quantal theory, its relation to the traditional hypothesis of hidden variables is discussed. 相似文献
75.
We extend the framework of entire cyclic cohomology to the equivariant context.Supported in part by the Department of Energy under Grant DE-FG02-88ER25065. 相似文献
76.
We construct the Chern character in the equivariant entire cyclic cohomology. We prove a general index theorem for theG-invariant Dirac operator.Supported in part by the Department of Energy under Grant DE-FG02-88ER25065. 相似文献
77.
Sniady A Durham A Morreale MS Marcinek A Szafert S Lis T Brzezinska KR Iwasaki T Ohshima T Mashima K Dembinski R 《The Journal of organic chemistry》2008,73(15):5881-5889
5-Endo-dig cycloisomerization of 1,4- and 1,2,4- mostly aryl-substituted but-3-yn-1-ones in the presence of a catalytic amount of zinc chloride etherate (10 mol %) in dichloromethane at room temperature gave 2,5-di- and 2,3,5-trisubstituted furans in high yields (85-97%). DSC studies confirmed that a solely thermal process does not take place. A relevant catalytic process, employing mu-oxo-tetranuclear zinc cluster Zn4(OCOCF3)6O, yielded bicyclic furopyrimidine nucleosides, when starting from acetyl-protected 5-alkynyl-2'-deoxyuridines (85-86%). Furopyrimidine was deprotected or simultaneously converted into pyrrolopyrimidine nucleoside. The time/concentration dependence for the reaction of 1-phenyl-4-(4-methylphenyl)butynone to 2-(4-methylphenyl)-5-phenylfuran displayed first-order kinetics with the rate dependent on catalyst concentration. The plot of ln k(obs) versus ln[ZnCl2] indicated first-order cycloisomerization, as referred to ZnCl2 concentration, using both NMR and UV-vis reaction monitoring. The crystal structure of propyl furopyrimidine nucleoside (orthorhombic, P2(1)2(1)2(1), a/b/c = 5.684(2)/6.682(2)/36.02(2) A, Z = 4) shows C2'- endo deoxyribose puckering, and the base is found in the anti position in crystalline form. 相似文献
78.
Shahram Solaymani Atefeh Ghaderi Slawomir Kulesza Mirosław Bramowicz 《Research on Chemical Intermediates》2017,43(4):2237-2240
In their recent article, Alipour et al. (Res Chem Intermed, 1. doi: 10.1007/s11164-016-2594-8) studied the effect of pressure on the morphological characteristics and quality of synthesized graphene from SEM data. Here, the basics of fractal calculations and depth histogram will be explained to avoid such egregious mistakes between using AFM, SEM and stereo SEM images by authors. 相似文献
79.
80.
Kalinowski S Koronkiewicz S Kotulska M Kubica K 《Bioelectrochemistry (Amsterdam, Netherlands)》2007,70(1):83-90
Chronopotentiometry on planar lipid bilayer (BLM) is proposed as a method for modeling the electrical phenomena in electroporated cell. Two techniques are discussed: constant-current and linear-current chronopotentiometry. It is proposed that the constant-current chronopotentiometry may provide basis for modeling the electroporated cell shortly after the removal of the electric field, when activity of cellular pumps counteracts ionic fluxes through the electropore and ionic channels. The linear-current method can be considered for modeling the cell in the later stage after electroporation, when energetical resources of the cell are gradually getting exhausted and the activity of pumps decreases. Based on this idea, it may be postulated that the electropore in the cell has fluctuating dynamics whose stochastic characteristics, similarly as biological channels, shows 1/f noise. The model implies that the fluctuations would disappear leaving the electropore with a constant resistance when efficiency of the pumps becomes very small. The results of chronopotentiometry also may suggest that opening time, conductivity and selectivity of the electropore can be controlled by the cell environment or membrane composition. 相似文献