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排序方式: 共有97条查询结果,搜索用时 31 毫秒
31.
Falko Wachholz Jan Gimsa Heiko Duwensee Harald Grabow Peter Gründler Gerd‐Uwe Flechsig 《Electroanalysis》2007,19(5):535-540
We describe a novel instrument and electrical circuit for sensitive electrochemical measurements at simultaneous direct electrode heating. The new measuring principle can be applied to working electrodes of various designs featuring two end contacts. In our experiments, the contacts were connected to a 100 kHz AC heating power supply and the potentiostat via the new inductor bridge circuit. A compact heating‐generator housing contains all components necessary for sine wave generation as well as amplification and transformation of the heating power. The new arrangement yields high temperature cyclovoltammetric signals for the [Fe(CN)6]3?/4? redox system with a noise level superior to the earlier symmetrically branched wire electrode designs. Noise and disturbances are dramatically suppressed especially for high resistance electrodes such as glassy carbon electrodes. Without a center contact, the working electrode design is greatly simplified. This opens new opportunities for the design of a great variety of heated electrodes that may be arranged in arrays or consist of materials with relatively high resistivity such as carbon and conducting polymers. 相似文献
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Polyclonal antisera to -amanitin were generated in sheep and used to construct a competitive ELISA for measurement of the toxin in human serum and urine. The assay had a detection limit of about 80 pg mL–1, a dynamic range of 80–2,000 pg mL–1, a cross reactivity of 22% with -amanitin, and no cross reactivities with cyclic peptides from algal sources. Assay responses in buffer, serum, and urine were remarkably similar. Coupling of the toxin to carrier proteins was carried out by previously unreported methods. The key step that allowed the construction of the highly sensitive assay was the introduction of a novel heterologous hapten derivative made of -amanitin-cyanuric chloride derivative. The new derivative overcame the problems of bridge binding that was, in this case, particularly serious with the homologous hapten derivative. The study demonstrated that the developed antiserum and ELISA procedure can be used to detect -amanitin and related toxins from Amanita phalloides in human serum and urine samples from suspected poison cases and enable early treatment to be administered. 相似文献
34.
Li-min?Zhao Bing?YanEmail author Qian-ming?Wang 《Monatshefte für Chemie / Chemical Monthly》2005,136(9):1545-1551
Summary. A kind of precursor molecule (abbreviated as EPDA–APMS) was synthesized by means of the amidation reaction of 5-ethylpyridine-2,3-dicarboxylic acid (EPDA) with a crosslinking molecule (3-aminopropyl)trimethoxysilane (APMS). Then the hybrid materials were obtained by reaction of this kind of monomer (EPDA–APMS), tetraethoxysilane (TEOS) and Tb(NO3)3·6H2O by an in-situ sol-gel process, resulting in a novel molecular hybrid material (named as Tb–EPDA–APMS) with double chemical bonds (Tb–O coordination bond and Si–O covalent bond). Ultraviolet absorption, phosphorescence, and fluorescence spectra were applied to characterize the photophysical properties of the obtained hybrid material. The strong luminescence of Tb3+ substantiates optimum energy match and effective intramolecular energy transfer between the triplet state energy of modified ligand bridge and emissive energy level of Tb3+. 相似文献
35.
Spectral assessment of mesh adaptations for the analysis of the dynamical longitudinal behavior of railway bridges 总被引:2,自引:0,他引:2
Summary Extensive studies, [1], concerning the longitudinal behavior of long railway bridges due to braking forces have been done
by measurements in situ, [2], and by statical, [3, 4], as well as dynamical simulations. Thereby, the only consistent numerical
realization with respect to the measured data was the dynamical one. However, the consecutive discretizations in space and
time with time-dependent system matrices are extremely time consuming due to the moving loads and varying stiffness of the
ballast under, and in front of, the moving train. Therefore, every effort should be made to optimize the discretization in
the space domain. This paper presents a strategy for assessing the quality of finite elements in space and for applying an
adaptive mesh-refinement for this special engineering problem. The method is characterized by a spectral assessment, comparing
a certain set of eigenvalues of the actual discretization with those of a very fine and rather exact numerical model. The
error estimator introduced in this paper controls a whole set of global eigenvalues with corresponding natural vibration modes
in order to assess certain types of shape functions. Thus, the procedure estimates local modifications on the one hand and
p-properties on the other by means of global indication.
Received 30 August 1999; accepted for publication 26 September 2000 相似文献
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《Discrete Mathematics》2019,342(7):1966-1978
We study methods for computing the bridge number of a knot from a knot diagram. We prove equivalence between a geometric and a combinatorial definition of the bridge number of a knot diagram. For each notion of diagrammatic bridge number considered, we find crossing number minimizing knot diagrams which fail to minimize bridge number. Furthermore, we construct a family of minimal crossing diagrams for which the difference between diagrammatic bridge number and the actual bridge number of the knot grows to infinity. 相似文献
38.
Effects of Surface Defects on Adsorption of CO and Methyl Groups on Rutile TiO$_\text{2}$(110)
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The interaction of reactants with catalysts has always been an important subject for catalytic reactions. As a promising catalyst with versatile applications, titania has been intensively studied for decades. In this work we have investigated the role of bridge bonded oxygen vacancy (O\begin{document}$_\textrm{v}$\end{document} ) in methyl groups and carbon monoxide (CO) adsorption on rutile TiO\begin{document}$_2$\end{document} (110) (R-TiO\begin{document}$_2$\end{document} (110)) with the temperature programmed desorption technique. The results show a clear different tendency of the desorption of methyl groups adsorbed on bridge bonded oxygen (O\begin{document}$_\textrm{b}$\end{document} ), and CO molecules on the five coordinate Ti\begin{document}$^{4+}$\end{document} sites (Ti\begin{document}$_{5\textrm{c}}$\end{document} ) as the O\begin{document}$_\textrm{v}$\end{document} concentration changes, suggesting that the surface defects may have crucial influence on the absorption of species on different sites of R-TiO\begin{document}$_2$\end{document} (110). 相似文献
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40.
以Tacoma大桥风振致毁事故为例, 研究H型桥面的风振机理. 分析了绕流场对称性的
破缺及其诱发桥面振动的情况; 并根据大桥实际尺寸, 采用Fluent软件进行了二维仿真计算.
结果表明: 桥面低压区从中部逐步形成并顺风向移动, 在上下桥面依次交替进行; 其二, 风
速越大, 桥面所受的阻力和升力变化周期越小, 周期变化速率也越小; 其三, 升力系数的变
化周期约为阻力系数变化周期的两倍, 在当时19m/s的风速条件下, 升力系数变化的周期约
为31.5s. 相似文献