全文获取类型
收费全文 | 156篇 |
免费 | 2篇 |
国内免费 | 3篇 |
专业分类
化学 | 83篇 |
力学 | 18篇 |
数学 | 43篇 |
物理学 | 17篇 |
出版年
2021年 | 1篇 |
2018年 | 1篇 |
2016年 | 4篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 6篇 |
2012年 | 5篇 |
2011年 | 9篇 |
2010年 | 3篇 |
2009年 | 3篇 |
2008年 | 10篇 |
2007年 | 12篇 |
2006年 | 7篇 |
2005年 | 7篇 |
2004年 | 9篇 |
2003年 | 4篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1966年 | 1篇 |
1962年 | 1篇 |
1961年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有161条查询结果,搜索用时 78 毫秒
151.
Colloid and Polymer Science - Die allgemeine volumetrische Spannungs-Dehnungs-Beziehung eines Zweiphasensystems ist hier in solcher Weise formuliert, da\ sie für elastische viskose (Kriechen)... 相似文献
152.
Dedicated to Professor Shmuel Agmon 相似文献
153.
A method is offered to estimate quantitatively the energy distribution of molecules reacting after being excited by multiphoton absorption of infrared radiation. The method is based on the comparison of the real time reaction kinetics obtained in the infrared multiphoton experiment with those observed upon excitation of a vibrational overtone. Results obtained for the dissociation of tetramethyldioxetane under low-pressure conditions are used as a demonstration. 相似文献
154.
A direct procedure for calculating resonance Raman scattering amplitudes for diatomic molecules is presented and compared with other calculational procedures. An extension of the present procedure is outlined for cases where there is more than one excited intermediate state and these states interact with one another. 相似文献
155.
156.
Yehuda Pinchover Kyril Tintarev 《Calculus of Variations and Partial Differential Equations》2007,28(2):179-201
Let Ω be a domain in , d ≥ 2, and 1 < p < ∞. Fix . Consider the functional Q and its Gateaux derivative Q′ given by If Q ≥ 0 on, then either there is a positive continuous function W such that for all, or there is a sequence and a function v > 0 satisfying Q′ (v) = 0, such that Q(u
k
) → 0, and in . In the latter case, v is (up to a multiplicative constant) the unique positive supersolution of the equation Q′ (u) = 0 in Ω, and one has for Q an inequality of Poincaré type: there exists a positive continuous function W such that for every satisfying there exists a constant C > 0 such that . As a consequence, we prove positivity properties for the quasilinear operator Q′ that are known to hold for general subcritical resp. critical second-order linear elliptic operators. 相似文献
157.
Nine novel compounds designated negombins A-I (1-9) were isolated, together with latrunculin, from the Tanzanian sponge Negombata sp. The nine are sacculatane type diterpenes, previously only known from liverworts. The structures of the compounds were elucidated by interpretation of MS and 1D and 2D NMR spectra. A possible biogenesis initiated by the naturally rare chloronium ion is suggested, possibly hinting to a guest microorganism as the source of the compounds. Compound 4 is toxic to brine shrimp larvae. 相似文献
158.
The energy and approximate structure of certain S(0)/S(1) conical intersections (CI) are shown computationally to be deducible from those of two bound states: the first triplet (T(1)), which is iso-energetic with the CI, and the second excited singlet state (S(2)). This is demonstrated for acepentalene (I) and its perfluoro derivative (II) using the twin state concept for three states systems and based on the fact that the triplet T(1) is almost degenerate with the CI. The stable S(2) (C(3v) configuration) state exhibits unusual exaltation of Jahn-Teller active degenerate mode-ν(JT) = 2058 cm(-1) (~500 cm(-1) higher than analogous e-mode of the symmetric (C(3v)) T(1) and the dianion I(-2) or any C-C vibration of the Jahn-Teller distorted (C(s)) ground state minimum). The acepentalene molecule, whose rigid structure and possibility to attain the relatively high symmetry C(3v) configuration, is a particularly suitable candidate for this purpose. 相似文献
159.
Density-dependent liquid nitromethane decomposition: molecular dynamics simulations based on ReaxFF 总被引:3,自引:0,他引:3
Rom N Zybin SV van Duin AC Goddard WA Zeiri Y Katz G Kosloff R 《The journal of physical chemistry. A》2011,115(36):10181-10202
The decomposition mechanism of hot liquid nitromethane at various compressions was studied using reactive force field (ReaxFF) molecular dynamics simulations. A competition between two different initial thermal decomposition schemes is observed, depending on compression. At low densities, unimolecular C-N bond cleavage is the dominant route, producing CH(3) and NO(2) fragments. As density and pressure rise approaching the Chapman-Jouget detonation conditions (~30% compression, >2500 K) the dominant mechanism switches to the formation of the CH(3)NO fragment via H-transfer and/or N-O bond rupture. The change in the decomposition mechanism of hot liquid NM leads to a different kinetic and energetic behavior, as well as products distribution. The calculated density dependence of the enthalpy change correlates with the change in initial decomposition reaction mechanism. It can be used as a convenient and useful global parameter for the detection of reaction dynamics. Atomic averaged local diffusion coefficients are shown to be sensitive to the reactions dynamics, and can be used to distinguish between time periods where chemical reactions occur and diffusion-dominated, nonreactive time periods. 相似文献
160.
We study the discreteness of the spectrum of Schrödinger operators which are defined on a class of radial N-dimensional rooted trees of a finite or infinite volume, and are subject to a certain mixed boundary condition. We present a method to estimate their eigenvalues using operators on a one-dimensional tree. These operators are called width-weighted operators, since their coefficients depend on the section width or area of the N-dimensional tree. We show that the spectrum of the width-weighted operator tends to the spectrum of a one-dimensional limit operator as the sections width tends to zero. Moreover, the projections to the one-dimensional tree of eigenfunctions of the N-dimensional Laplace operator converge to the corresponding eigenfunctions of the one-dimensional limit operator. 相似文献