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331.
This paper deals with the thickness-twist vibration of a multi-layered rectangular piezoelectric plate of crystals of 6 mm symmetry or polarized ceramics.An exact solution is obtained from the three-dimensional equations of linear piezoelectricity.The solution is useful to the understanding and design of composite piezoelectric devices.A piezoelectric resonator,a piezoelectric transformer,and a piezoelectric generator are analyzed as examples. 相似文献
332.
333.
Yuyan Liu Yuanqing Guo Hongping Liu Xiaoyong Liu Jieli Lin Guangming Huang Jinrui Li Fengyan Li 《中国科学B辑(英文版)》2000,43(3):261-267
From the theories of the nuclear hyperfine structure (HFS) and Λ doubling of diatomic molecules, several brief algebraic equations
for interpretation of HFS and Λ doubling of transitions of diatomic molecule have been developed. A few important parameters
of HFS and Λ doubling of15N16O have been efficiently and accurately obtained from the analysis of the high resolution spectra of15N16O (X2∏) observed in our experiments with these equations. This method can provide an effective approach to obtain important hyperfine
parameters of novel radicals from their high resolution laser magnetic resonance spectra.
Liu Yu-yan, Guo Yuan-qing, Assignments of FIR-LMR spectra of CF X2∏(υ= 1) and MIR-LMR spectra of NO X2∏ (υ =1←0), Spectroscopy and Spectral Analysis (in press). 相似文献
334.
335.
以飞秒400及266 nm激光脉冲结合泵浦-探测飞行时间质谱方法研究了苯S2态内转换动力学. 400 nm双光子过程将苯分子激发到S2电子态,布居在S2电子态的分子由于能级耦合无辐射弛豫到S1电子态. 通过测定C6H6+讯号强度随泵浦-探测延迟时间的改变,获得苯S2及S1电子态的衰减寿命分别为(48±1)fs及(6.5±0.2)ps, S2态及S1电子态的消激发机理被认为是相应势能面间的锥形交叉引起的内转换. 相似文献
336.
陈述了几种获取飞秒泵浦-探测实验数据中的光解动力学信息的解析物理模型.其中单分量和双分量模型用来解释母体分子的单通道和双通道解离过程,另一个单分量模型用来解释碎片分子的解离或去激发过程.所有模型都结合泵浦-探测实验数据予以解释. 相似文献
337.
基于非结构网格,给出模拟两相流的统一间断有限元框架.其中,不可压Navier-Stokes方程采用IPDG(Interior penalty discontinuous Galerkin)方法求解;Level Set方程采用RKDG(Runge-Kutta discontinuous Galerkin)方法求解.方腔驱动流在不同Re数时的数值结果验证了该方法在单相流动中的有效性.气泡上升过程的模拟结果表明:该方法避免了重新初始化,且计算量小、实施简单,可有效求解具有运动界面的不可压两相流问题. 相似文献
338.
Zhang X Han B Hou Z Zhang J Liu Z Jiang T He J Li H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(22):5107-5111
The effects of two polar co-solvents, chlorodifluoromethane and acetone, on the solubility and enthalpy of a solution of 1,4-naphthoquinone in supercritical (SC) CO2 were studied. We found that the dissolution process becomes less exothermic in the presence of the co-solvents relative to that in pure CO2, although the solubility is enhanced significantly by the co-solvents. This indicates that the increase in the solubility by adding co-solvents results from the increase of the entropy of solution. On the basis of the unexpected results we propose a new mechanism for the solubility enhancement of the solute by the co-solvents in supercritical fluids (SCF); this should be applicable to cases in which the local density of the SC solvent around the solute and the co-solvent is larger, and the co-solvent associates preferentially with the solute. The results are also very important for the understanding of other fundamental questions of SCF science, such as the effect of co-solvents on the thermodynamic and kinetic properties of the reactions in SCFs. 相似文献
339.
Weida Tong Hongping Ye Ding Rong Valerian T. D'Souza 《Journal of computational chemistry》1992,13(5):614-621
A computational chemistry study of the artificial redox enzyme synthesized by covalently attaching flavin to cyclodextrins explains some of its properties. Calculations indicate that the flavin moiety covalently attached to cyclodextrin is not within the cavity of cyclodextrin. This result is consistent with the UV-vis spectrum of the artificial enzyme. The calculations also indicate hydrogen bonds formed between the carbonyl groups of the catalytic functionality and the hydroxyl groups of cyclodextrin play a role in their most stable conformation. This explains the observed overall stability of these artificial enzymes compared to riboflavin. Electrostatic energies and solvation energies play a major role in the stability of the hosts and the orientation of guests included within the artificial enzymes. The rates of oxidation of various thiols catalyzed by the artificial enzyme can be explained by the relative distances between the sulfur atom of the substrates and C(4a) of the flavin moiety. 相似文献
340.
Equilin-3-sulfate and delta8,9-dehydroestrone-3-sulfate are two isomers found in equine conjugated estrogens that differ in structure only by the position of a double bond in the steroid B-ring. These geometric isomers were not resolved on a C18 column during the analysis of conjugated estrogen drug products by LC-MS using acetonitrile-ammonium acetate buffer as the mobile phase. While no separations of these two isomers were observed on C18 or other alkyl-bonded silica based phases using a variety of mobile phase conditions, partial separations were achieved on phenyl bonded silica phases with a resolution of 1.5 on a diphenyl phase, and baseline separations were readily achieved on two carbonaceous phases with resolutions routinely exceeding three on graphitic carbon-coated zirconia (Zr-CARB) and resolutions as high as 19 on porous graphitic carbon (Hypercarb). An examination of a selected few conjugated estrogens in the complex drug substance by LC-MS on Hypercarb is presented. 相似文献