全文获取类型
收费全文 | 1025篇 |
免费 | 8篇 |
国内免费 | 3篇 |
专业分类
化学 | 773篇 |
晶体学 | 16篇 |
力学 | 6篇 |
数学 | 80篇 |
物理学 | 161篇 |
出版年
2021年 | 8篇 |
2020年 | 4篇 |
2019年 | 18篇 |
2016年 | 12篇 |
2015年 | 14篇 |
2014年 | 8篇 |
2013年 | 69篇 |
2012年 | 27篇 |
2011年 | 50篇 |
2010年 | 24篇 |
2009年 | 31篇 |
2008年 | 47篇 |
2007年 | 43篇 |
2006年 | 48篇 |
2005年 | 42篇 |
2004年 | 37篇 |
2003年 | 41篇 |
2002年 | 42篇 |
2001年 | 17篇 |
2000年 | 16篇 |
1999年 | 15篇 |
1998年 | 17篇 |
1997年 | 14篇 |
1996年 | 24篇 |
1995年 | 4篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 10篇 |
1991年 | 17篇 |
1990年 | 9篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 24篇 |
1984年 | 20篇 |
1983年 | 13篇 |
1982年 | 21篇 |
1981年 | 20篇 |
1980年 | 35篇 |
1979年 | 24篇 |
1978年 | 23篇 |
1977年 | 28篇 |
1976年 | 7篇 |
1975年 | 15篇 |
1974年 | 8篇 |
1973年 | 8篇 |
1971年 | 3篇 |
1968年 | 4篇 |
1958年 | 3篇 |
排序方式: 共有1036条查询结果,搜索用时 15 毫秒
101.
Shigekazu Ito Joji Miura Noboru Morita Masaaki Yoshifuji Anthony J. Arduengo 《Comptes Rendus Chimie》2010,13(8-9):1180-1184
A new class of 1,3-diphoshacyclobutane-2,4-diyls bearing alkylsulfanyl or arylsulfanyl groups together with the sterically demanding Mes* groups have been prepared as air-stable compounds.
102.
Noboru Watanabe 《Foundations of Physics》2011,41(3):549-563
We review some techniques and notions for quantum information theory. It is shown that the dynamical entropies is discussed
and some numerical computations of these entropies are carried for several states. 相似文献
103.
André Luiz Tessaro Vagner Roberto Batistela Augusto César Gracetto Hueder Paulo Moisés de Oliveira Rosana Lazara Sernaglia Vagner Roberto de Souza Wilker Caetano Noboru Hioka 《Journal of Physical Organic Chemistry》2011,24(2):155-161
Benzoporphyrin monoacid derivatives, here named B3A and B3B, are promising new drugs for photodynamic therapy. Although both isomers show interesting characteristics as photosensitizing compounds, they have some distinct physicochemical properties such as the tendency to self‐aggregate in water‐rich media. Because pH drives the presence of each species, the pKa of these compounds assumes strategic importance. However, traditional micro‐titration methods and UV–Vis absorption techniques fail to give reliable pKa values due to the characteristics of this highly complex system, such as the precipitation of hydrophobic species, close pKa values, and high absorption band superposition. In the present work, chemometric tools are employed to evaluate pKa, and the kinetic tendency of monomers to undergo self‐aggregation is investigated. In solvent mixtures at low water percentage in ethanol, both B3A and B3B are stabilized in a monomeric state. However, in mixtures with a high water content, self‐aggregation takes place, mainly under a mild pH acid condition (3 < pH < 6), in which the prevalent protolytic species of both isomers is the neutral charged form, compounds with carboxylic and porphyrin free‐base groups. It is demonstrated that both isomers can undergo aggregation following a self‐catalytic mechanism, which is 2000 times slower to B3A than B3B. For B3A, the aggregation is manifested by a decrease in the monomer band with the aggregation band probably superposed to that of the monomer. For B3B, together with the decrease in the monomer band, a new band related to self‐aggregates is observed. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
104.
Wakabayashi Y 《J Phys Condens Matter》2011,23(48):483001
The atomic arrangement in a solid contains a great amount of information, and observation of its structure is essential for understanding the electronic and magnetic properties of transition metal oxides at a microscopic level. Increasing interest in the surfaces and interfaces of oxide systems, which is partly driven by the anticipation of device applications, enhances the importance of structural studies of the near-surface region. We review various types of structural studies with x-ray scattering on the near-surface region of metal oxides-from thick films to surfaces-in order to clarify the structural effects on their electronic properties. 相似文献
105.
106.
107.
108.
109.
Sasanuma Y Nishimura F Wakabayashi H Suzuki A 《Langmuir : the ACS journal of surfaces and colloids》2004,20(3):665-672
Conformational characteristics of 1-butanol incorporated not only in hexagonal and lamellar aggregates formed by a lyotropic liquid crystal composed of sodium octanoate, 1-butanol, and water but also in a thermotropic liquid crystal, 4'-methoxybenzylidene-4-n-butylaniline (MBBA), have been investigated from 2H NMR quadrupolar splittings of the perdeuterated and partially deuterated compounds. In the lyotropic phases, 1-butanol shows strong trans preferences and renders itself extended, and octanoate decreases the trans fraction toward the methyl terminal to fill the inner space of the aggregate on behalf of 1-butanol. In MBBA, 1-butanol prefers globular conformations. This tendency was also indicated from the phase behaviors of 1-butanol/MBBA and 1-decanol/MBBA systems. In the nematic field, two successive C-C bonds of 1-butanol mostly adopt g+/-g+/- conformations, which are formed in the vicinity of the headgroup of 1-decanol in the lamella of the sodium octanoate/1-decanol/water system. A large degree ofconformational freedom near the hydroxyl group of alcohols, being shown by ab initio molecular orbital calculations at the Gaussian-2 level, permits them to change conformation for each environment. 相似文献
110.
The band structure of graphene ribbons with zigzag edges have two valleys well separated in momentum space, related to the two Dirac points of the graphene spectrum. The propagating modes in each valley contain a single chiral mode originating from a partially flat band at the band center. This feature gives rise to a perfectly conducting channel in the disordered system, if the impurity scattering does not connect the two valleys, i.e., for long-range impurity potentials. Ribbons with short-range impurity potentials, however, through intervalley scattering display ordinary localization behavior. The two regimes belong to different universality classes: unitary for long-range impurities and orthogonal for short-range impurities. 相似文献