全文获取类型
收费全文 | 1345篇 |
免费 | 23篇 |
国内免费 | 13篇 |
专业分类
化学 | 1042篇 |
晶体学 | 20篇 |
力学 | 15篇 |
数学 | 84篇 |
物理学 | 220篇 |
出版年
2023年 | 7篇 |
2021年 | 7篇 |
2019年 | 13篇 |
2018年 | 8篇 |
2017年 | 7篇 |
2016年 | 17篇 |
2015年 | 15篇 |
2014年 | 16篇 |
2013年 | 87篇 |
2012年 | 44篇 |
2011年 | 62篇 |
2010年 | 42篇 |
2009年 | 38篇 |
2008年 | 70篇 |
2007年 | 78篇 |
2006年 | 86篇 |
2005年 | 82篇 |
2004年 | 69篇 |
2003年 | 69篇 |
2002年 | 77篇 |
2001年 | 25篇 |
2000年 | 34篇 |
1999年 | 13篇 |
1998年 | 18篇 |
1997年 | 19篇 |
1996年 | 19篇 |
1995年 | 14篇 |
1994年 | 23篇 |
1993年 | 12篇 |
1992年 | 16篇 |
1991年 | 7篇 |
1990年 | 14篇 |
1989年 | 9篇 |
1988年 | 19篇 |
1987年 | 5篇 |
1986年 | 10篇 |
1985年 | 16篇 |
1984年 | 23篇 |
1983年 | 14篇 |
1982年 | 21篇 |
1981年 | 22篇 |
1980年 | 7篇 |
1979年 | 22篇 |
1978年 | 13篇 |
1977年 | 15篇 |
1976年 | 13篇 |
1975年 | 18篇 |
1974年 | 13篇 |
1973年 | 10篇 |
1972年 | 5篇 |
排序方式: 共有1381条查询结果,搜索用时 15 毫秒
121.
122.
A laser-heated sample in a diamond anvil cell and synchrotron X-ray radiation was used to carry out structural characterization of the phase transformation of Fe2O3 at high pressures (30-96 GPa) and high temperature. The Rh2O3(II) (or orthorhombic perovskite) structure transforms to a new phase, which exhibits X-ray diffraction data that are indicative of a CaIrO3-type structure. The CaIrO3-type structure exhibited an orthorhombic symmetry (space group: Cmcm) that was stable at temperatures of 1200-2800 K and pressure of 96 GPa (the highest pressure used). Unambiguous assignment of such a structure requires experimental evidence for the presence of two Fe species. Based on the equation of state of gold, the phase boundary of the CaIrO3-type phase transformation was P (GPa)=59+0.0022×(T−1200) (K). 相似文献
123.
Iwao Okamoto Mayumi Nabeta Misaki Yamamoto Maiko Mikami Tetsuya Takeya Osamu Tamura 《Tetrahedron letters》2006,47(40):7143-7146
An aromatic N-methyl amide containing N-(2-pyridyl) and 2,6-pyridinedicarboxamide moieties switches its conformation from cis to trans depending upon the acceptor number of solvents. 相似文献
124.
Komal Garg Yasuo Matsubara Mehmed Z. Ertem Anna Lewandowska‐Andralojc Shunsuke Sato David J. Szalda James T. Muckerman Etsuko Fujita 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(47):14334-14338
We prepared two geometric isomers of [Ir(tpy)(ppy)H]+, previously proposed as a key intermediate in the photochemical reduction of CO2 to CO, and characterized their notably different ground‐ and excited‐state interactions with CO2 and their hydricities using experimental and computational methods. Only one isomer, C‐trans‐[Ir(tpy)(ppy)H]+, reacts with CO2 to generate the formato complex in the ground state, consistent with its calculated hydricity. Under photocatalytic conditions in CH3CN/TEOA, a common reactive C‐trans‐[Ir(tpy)(ppy)]0 species, irrespective of the starting isomer or monodentate ligand (such as hydride or Cl), reacts with CO2 and produces CO with the same catalytic efficiency. 相似文献
125.
Watanabe M Yamamoto T Yamamoto A Obana E Niiyama K Hada T Ooie T Kataoka M Hori T Houchi H Shinohara Y 《Applied biochemistry and biotechnology》2011,165(2):538-547
The thermogenic function of brown adipose tissue (BAT) is known to be markedly elevated when animals are exposed to the cold, and intensive studies have been carried out to understand the molecular basis enabling effective thermogenesis in cold-exposed animals. In this study, we used microarray analysis to examine the effects of cold exposure of animals on their gene expression profiles in white adipose tissue (WAT), which seems to function as a counterpart tissue of BAT. The results indicate that the effects of cold exposure on the gene expression profiles of WAT were much more moderate than the effects on those of BAT. Possible reasons for the different responses of BAT and WAT to cold exposure are discussed. 相似文献
126.
127.
Reversible waves of voltammetry with complex non-unity stoichiometry are studied here based on theory. Numerical simulations
were performed for various stoichiometric systems in which coefficients m and q were independently varied from 1 to 4 in a general reaction scheme, mO + ne− ai qR. The calculation results indicate that the peak current function at complex stoichiometry differs from that at simple unity
stoichiometry. The relation between the half-wave potential and the formal potential has been partially corrected from that
previously reported in the literature. Parameters in the relation between the peak potential and the half-wave potential are
unique for each stoichiometric system. The parameter in the relation between the peak potential and the half-peak potential
is also presented here. 相似文献
128.
Fuzzy measures are used in conjunction with fuzzy integrals for aggregation. Their role in the aggregation is to permit the user to express the importance of the information sources (either criteria or experts). Due to the fact that fuzzy measures are set functions, the definition of such measures requires the definition of 2n parameters, where n is the number of information sources. To make the definition easier, several families of fuzzy measures have been defined in the literature.In this paper m-separable fuzzy measures are introduced. We present some results on this type of measures and we relate them to some of the previous existing ones. We study generating functions for m-separable fuzzy measures and some properties related to these generating functions. 相似文献
129.
Ono RJ Suzuki Y Khramov DM Ueda M Sessler JL Bielawski CW 《The Journal of organic chemistry》2011,76(9):3239-3245
Coupling of various 4-substituted phenyl azides with two distinct quinone-containing N-heterocyclic carbenes (NHCs) afforded the respective mono- and ditopic 1,3-disubstituted acyclic triazenes in moderate to excellent yields (38-92%). Depending on their pendant substituents (derived from the azides), the acyclic triazenes exhibited intense absorptions in the visible spectrum (359-428 nm), which were bathochromically shifted by up to Δλ=68 nm upon reduction of the quinone moiety on the component derived from the NHC. Cyclic voltammetry confirmed that the aforementioned redox processes were reversible, and a related set of UV-vis spectroelectrochemical experiments revealed that bulk electrolysis may also be used to switch reversibly the colors exhibited by these triazenes. 相似文献
130.
Kataoka M Kouda Y Sato K Minakawa N Matsuda A 《Chemical communications (Cambridge, England)》2011,47(30):8700-8702
The synthesis of the 3'-deoxyapionucleoside 3'-triphosphates (apioNTPs) having the four natural nucleobases and their enzymatic incorporation into a DNA-DNA primer-template have been tried. Therminator DNA polymerase was shown to incorporate these apioNTPs effectively giving 43mer DNA-apioNA chimera. 相似文献