全文获取类型
收费全文 | 118篇 |
免费 | 0篇 |
专业分类
化学 | 76篇 |
晶体学 | 1篇 |
力学 | 6篇 |
数学 | 17篇 |
物理学 | 18篇 |
出版年
2021年 | 2篇 |
2020年 | 1篇 |
2018年 | 2篇 |
2015年 | 3篇 |
2014年 | 1篇 |
2013年 | 3篇 |
2012年 | 4篇 |
2011年 | 8篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 7篇 |
2007年 | 4篇 |
2006年 | 7篇 |
2005年 | 3篇 |
2004年 | 3篇 |
2003年 | 5篇 |
2002年 | 5篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1979年 | 1篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1969年 | 2篇 |
1968年 | 3篇 |
1957年 | 1篇 |
1935年 | 1篇 |
1934年 | 1篇 |
1931年 | 1篇 |
排序方式: 共有118条查询结果,搜索用时 218 毫秒
1.
2.
A quantitative compressed pellet infrared method used together with a micro-distillation to effect separation of the isomer has been developed and reported here for the analysis of ortho-, meta-, and para-terphonyl. The terphenyl content is determined on fractions isolated by distillation from radiation damaged samples. The compressed pellet infrared method is preferred instead of the more conventional solution technique since smaller quantities of isolated terphcnyl are required. The pellet method is applicable also to polyphenyls higher than the terphenyls. The solution technique is not due to the insolubility of the polyphenyls. It is expected that the compressed pellet spectral method developed here might well find application in the analysis of compounds other than polyphenyls. Results presented here appear to be the, first quantitative infrared data reported in the literaturu on polyphenyl compounds. 相似文献
3.
Jochen Lutz The Vinh Ho Richard H. Fish Andreas Schmid 《Journal of organometallic chemistry》2004,689(25):4783-4790
The biocatalytic, regioselective hydroxylation of 2-hydroxybiphenyl to the corresponding catechol was accomplished utilizing the monooxygenase 2-hydroxybiphenyl 3-monooxygenase (HbpA). The necessary natural 1,4-dihydronicotinamde adenine dinucleotide (NADH) co-factor for this biocatalytic process was replaced by a biomimetic co-factor, N-benzyl-1,4-dihydronicotinamide, 1b. The interaction between the flavin (FAD) containing HbpA enzyme and the corresponding biomimetic NADH compound, N-benzyl-1,4-dihdronicotinamide, 1b, for hydride transfer, was shown to readily occur. The in situ recycling of the reduced NADH biomimic 1b from 1a was accomplished with [Cp*Rh(bpy)H](Cl); however, productive coupling of this regeneration reaction to the enzymatic hydroxylation reaction was not totally successful, due to a deactivation process concerning the HbpA enzyme peripheral groups; i.e., -SH or -NH2 possibly reacting with the precatalyst, [Cp*Rh(bpy)(H2O)](Cl)2, and thus inhibiting the co-factor regeneration process. The deactivation mechanism was studied, and a promising strategy of derivatizing these peripheral -SH or -NH2 groups with a polymer containing epoxide was successful in circumventing the undesired interaction between HbpA and the precatalyst. This latter strategy allowed tandem co-factor regeneration using 1a or 2a, [Cp*Rh(bpy)(H2O)](Cl)2, and formate ion, in conjunction with the polymer bound, FAD containing HbpA enzyme to provide the catechol product. 相似文献
4.
Jin proved that whenever A and B are sets of positive upper density in Z, A+B is piecewise syndetic. Jin's theorem was subsequently generalized by Jin and Keisler to a certain family of abelian groups, which in particular contains Zd. Answering a question of Jin and Keisler, we show that this result can be extended to countable amenable groups. Moreover we establish that such sumsets (or — depending on the notation — “product sets”) are piecewise Bohr, a result which for G=Z was proved by Bergelson, Furstenberg and Weiss. In the case of an abelian group G, we show that a set is piecewise Bohr if and only if it contains a sumset of two sets of positive upper Banach density. 相似文献
5.
Trent D Lund Timothy W West Lilyan Y Tian Lihong H Bu Daniel L Simmons Kenneth DR Setchell Herman Adlercreutz Edwin D Lephart 《BMC neuroscience》2001,2(1):20-13
Background
In learning and memory tasks, requiring visual spatial memory (VSM), males exhibit superior performance to females (a difference attributed to the hormonal influence of estrogen). This study examined the influence of phytoestrogens (estrogen-like plant compounds) on VSM, utilizing radial arm-maze methods to examine varying aspects of memory. Additionally, brain phytoestrogen, calbindin (CALB), and cyclooxygenase-2 (COX-2) levels were determined. 相似文献6.
7.
8.
Jacob Fish 《Journal of nanoparticle research》2006,8(5):577-594
This review article describes various multiscale approaches, development of which was spurred by the emergence of nanotechnology. The multiscale approaches are grouped into two main categories: information-passing and concurrent. In the concurrent multiscale methods both, the discrete and continuum scales are simultaneously resolved, whereas in the information-passing schemes, the discrete scale is modelled and its gross response is infused into the continuum scale. Most of the information-passing approaches provide sublinear computational complexity, (i.e., scales sublinearly with the cost of solving a fine scale problem), but the quantities of interest are limited to or defined only on the coarse scale. The issues of appropriate scale selection and uncertainty quantification are also reviewed. 相似文献
9.
10.
A computationally efficient two-level iterative scheme is proposed for the solution of the interface problems with Lagrange multipliers, where the oscillatory part of the solution is resolved by means off smoothing using a new, efficient preconditioner whereas the smooth component of the solution is captured by the collocation-based problem on the auxilliary grid, that is solved directly using a sparse direct solver. A simple adaptive feature is built into the proposed solution method in order to guarantee convergence for ill-conditioned problems. Nmerical results presented for example problems including that of a Boeing crown panel show that the proposed tww-level solution technique outperfrmsnce the standard, single level iterative and direect solvers. 相似文献