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排序方式: 共有159条查询结果,搜索用时 0 毫秒
31.
A solution for the two-dimensional temperature field in a workpiece at welding by laser or electron beams, which takes into consideration the solid-to-liquid phase change of the material, is presented. This leads to more precise process parameter correlations. 相似文献
32.
Ronen Kreizman Sung You Hong Jeremy Sloan Dr. Ronit Popovitz‐Biro Dr. Ana Albu‐Yaron Dr. Gerard Tobias Dr. Belén Ballesteros Dr. Benjamin G. Davis Prof. Malcolm L. H. Green Prof. Reshef Tenne Prof. 《Angewandte Chemie (International ed. in English)》2009,48(7):1230-1233
Multiwall WS 2 nanotube templates were used as hosts to prepare core–shell PbI2@WS2 nanotubes by a capillary‐wetting method. Conformal growth of PbI2 layers on the inner wall of the relatively wide WS2 nanotubes (i.d. ca. 10 nm) leads to nanotubular structures which were not previously observed in narrow carbon nanotube templates. Image simulation after structural modeling (see picture) showed good agreement with the experimental HRTEM image.
33.
de Visser SP Kumar D Cohen S Shacham R Shaik S 《Journal of the American Chemical Society》2004,126(27):8362-8363
The communication presents DFT calculations of 10 different C-H hydroxylation barriers by the active species of the enzyme cytochrome P450. The work demonstrates the existence of an excellent barrier-bond energy correlation. The so-obtained equation of the straight line is demonstrated to be useful for predicting barriers of related C-H activation processes, as well as for assessing barrier heights within the protein environment. This facility is demonstrated be estimating the barrier of camphor hydroxylation by P450cam. 相似文献
34.
We prove that any ? positive definite d × d matrices, M1,...,M?, of full rank, can be simultaneously spectrally balanced in the following sense: for any k < d such that ? ≤ \(\ell \leqslant \left\lfloor {\frac{{d - 1}}{{k - 1}}} \right\rfloor \), there exists a matrix A satisfying \(\frac{{{\lambda _1}\left( {{A^T}{M_i}A} \right)}}{{Tr\left( {{A^T}{M_i}A} \right)}} < \frac{1}{k}\) 1/k for all i, where λ1(M) denotes the largest eigenvalue of a matrix M. This answers a question posed by Peres, Popov and Sousi ([PPS13]) and completes the picture described in that paper regarding sufficient conditions for transience of self-interacting random walks. Furthermore, in some cases we give quantitative bounds on the transience of such walks. 相似文献
35.
36.
Y. Peretz 《Linear algebra and its applications》2012,437(2):525-548
In this article, we give a complete characterization (geared towards a parametrization) of all the static feedbacks of a given LTI system triplet, in terms of the coefficients of some reduced order Riccati equation, with simultaneously stabilizing solutions and structural constraints – on the coefficients. 相似文献
37.
Marielle Christiansen Kjetil Fagerholt Bjørn Nygreen David Ronen 《European Journal of Operational Research》2013
We review research on ship routing and scheduling and related problems during the new millennium and provide four basic models in this domain. The volume of research in this area about doubles every decade as does the number of research outlets. We have found over a hundred new refereed papers on this topic during the last decade. Problems of wider scope have been addressed as well as more specialized ones. However, complex critical problems remain wide open and provide challenging opportunities for future research. 相似文献
38.
Faina Gelman Anna Kotlyar Daniel Chiguala Zeev Ronen 《International journal of environmental analytical chemistry》2013,93(14):1392-1400
A new analytical method is presented for the compound-specific carbon and nitrogen isotope ratio analysis of a thermo-labile nitramine explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by gas chromatograph coupled to an isotope ratio mass spectrometer (GC-IRMS). Two main approaches were used to minimise thermal decomposition of the compound during gas chromatographic separation: programmed temperature vaporisation (PTV) as an injection technique and a high-temperature ramp rate during the GC run. δ15N and δ13C values of RDX measured by GC-IRMS and elemental analyser (EA)-IRMS were in good agreement within a standard deviation of 0.3‰ and 0.4‰ for nitrogen and carbon, respectively. Application of the method for the isotope analysis of RDX during alkaline hydrolysis at 50°C revealed isotope fractionation factors ε carbon?=??7.8‰ and ε nitrogen?=??5.3‰. 相似文献
39.
The effect of salts on the solvent-induced interactions between hydrophobic particles dispersed in explicit aqueous solution is investigated as a function of the salt's ionic charge density by molecular dynamics simulations. We demonstrate that aggregates of the hydrophobic particles can be formed or dissolved in response to changes in the charge density of the ions. Ions with high charge density increase the propensity of the hydrophobic particles to aggregate. This corresponds to stronger hydrophobic interactions and a decrease in the solubility (salting-out) of the hydrophobic particles. Ions with low charge density can either increase or decrease the propensity for aggregation depending on whether the concentration of the salt is low or high, respectively. At low concentrations of low charge density ions, the aggregate forms a "micelle-like" structure in which the ions are preferentially adsorbed at the surface of the aggregate. These "micelle-like" structures can be soluble in water so that the electrolyte can both increase the solubility and increase aggregation at the same time. We also find, that at the concentration of the hydrophobic particles studied (approximately 0.75 m), the aggregation process resembles a first-order transition in finite systems. 相似文献
40.
Molecular Insight into Long‐Wavelength Fluorogenic Dye Design: Hydrogen Bond Induces Activation of a Dormant Acceptor 下载免费PDF全文
Michal Roth Ronen Ben‐Eliyahu Prof. Dr. Doron Shabat 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(51):18566-18570
The detection of chemical or biological analytes in response to molecular changes relies increasingly on fluorescence methods. Therefore, there is a substantial need for the development of improved fluorogenic dyes. In this study, we demonstrated how an intramolecular hydrogen bond activates a dormant acceptor through a charge induction between phenolic hydrogen and a heteroaryl nitrogen moiety. As a result, a new fluorochrome is produced, and the molecule exhibits a strong fluorescent emission. When the strength of the hydrogen bonding was increased by conformational locking, the obtained dye emitted at longer wavelengths and fluoresced under physiological conditions. The dye was implemented in a turn‐ON system responsive to hydrogen peroxide. The molecular insight provided by this study should assist in the design of fluorescent dyes that are suitable for in vitro and in vivo applications. 相似文献