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The topological network design of general service, finite waiting room, multi-server queueing networks is a complex optimization problem. Series, merge, and split topologies are examined using an approximation method to estimate the performance of these queueing networks and an iterative search methodology to find the optimal buffer allocation within the network. The coefficient of variation is shown to be a significant factor in the buffer allocation for multiple servers in uniform and bottleneck server networks. Extensive computational results are included to illustrate the symmetries and asymmetries in the buffer patterns which emerge from the series, merge, and splitting topologies. 相似文献
54.
We present a formalism of Galilean quantum mechanics in non-inertial reference frames and discuss its implications for the equivalence principle. This extension of quantum mechanics rests on the Galilean line group, the semidirect product of the real line and the group of analytic functions from the real line to the Euclidean group in three dimensions. This group provides transformations between all inertial and non-inertial reference frames and contains the Galilei group as a subgroup. We construct a certain class of unitary representations of the Galilean line group and show that these representations determine the structure of quantum mechanics in non-inertial reference frames. Our representations of the Galilean line group contain the usual unitary projective representations of the Galilei group, but have a more intricate cocycle structure. The transformation formula for the Hamiltonian under the Galilean line group shows that in a non-inertial reference frame it acquires a fictitious potential energy term that is proportional to the inertial mass, suggesting the equivalence of inertial mass and gravitational mass in quantum mechanics. 相似文献
55.
Andrea Weiss Laurence Williams J. MacGregor Smith 《Journal of Mathematical Modelling and Algorithms》2012,11(4):361-386
Evacuation networks from buildings represent a complex architectural and engineering phenomenon. The problem is fundamentally a transient stochastic process embedded on a three-dimensional graph network topology. Not only is the analysis of the problem challenging, but synthesizing the way occupants should exit the facility is also problematic. This paper addresses the two key concerns in the evacuation problem: performance analysis and their optimization. Two facilities on the University of Massachusetts campus provide the backdrop and case studies for this paper. Extensive computational results support the theoretical decomposition approach to the problems. 相似文献
56.
The Multi-Story Space Assignment Problem (MSAP) is an innovative formulation of the multi-story facility assignment problem
that allows one to model the location of departments of unequal size within multi-story facilities as a Generalized Quadratic
3-dimensional Assignment Problem (GQ3AP). Not only can the MSAP generate the design of the location of the departments in
the facility, the MSAP also includes the evacuation planning for the facility. The formulation, background mathematical development,
and computational experience with a branch and bound algorithm for the MSAP are also presented. 相似文献
57.
Resonant ultrasound spectroscopy was used to measure the elastic constants of bcc Ta0.33V0.67 over the temperature range 3.5–300?K; the results were compared to earlier measurements on C15 TaV2. The temperature dependence of the polycrystalline shear modulus is completely different in the two phases; that of the bcc phase decreases with temperature whereas that of the C15 phases increases in an anomalous fashion. This difference is consistent with a model involving doubly-degenerate levels at the X point of the Brillouin zone in the C15 phase with the Fermi level lying near the doubly degenerate level. This model accounted for the unusual behaviour of the C15 phase. Debye temperatures were determined from the ultrasonic measurements: 295?K for the C15 phase and 315?K for the bcc phase. 相似文献
58.
DS Zhulai SA Bugaychuk GV Klimusheva TA Mirnaya VN Asaula VI Handziuk 《Liquid crystals》2017,44(8):1269-1276
The class of thermotropic ionic liquid crystals (LCs) of the metal alkanoates possesses a number of unique properties, such as intrinsic ionic conductivity, high dissolving ability and ability to form time-stable mesomorphic glasses. These ionic LCs can be used as nanoreactors for the synthesis and stabilisation of different types of nanoparticles (NPs). Thus, some semiconductors, metals and core/shell NPs were chemically synthesised in the thermotropic ionic liquid crystalline phase (smectic A) of the cadmium octanoate (CdC8) and of the cobalt octanoate (CoC8). By applying the scanning electron microscopy, the cadmium and cobalt octanoate composites containing CdS, Au, Ag and core/shell Au/CdS NPs have been studied. NPs’ sizes and dispersion distribution of the NPs’ size in the nanocomposites have been obtained. 相似文献
59.
Michelle Maclean Lynne E. Murdoch Scott J. MacGregor John G. Anderson 《Photochemistry and photobiology》2013,89(1):120-126
Resistance of bacterial endospores to treatments, including biocides, heat and radiation is a persistent problem. This study investigates the susceptibility of Bacillus and Clostridium endospores to 405 nm visible light, wavelengths which have been shown to induce inactivation of vegetative bacterial cells. Suspensions of B. cereus endospores were exposed to high‐intensity 405 nm light generated from a light‐emitting diode array and results demonstrate the induction of a sporicidal effect. Up to a 4‐log10 CFU mL?1 reduction in spore population was achieved after exposure to a dose of 1.73 kJ cm?2. Similar inactivation kinetics were demonstrated with B. subtilis, B. megaterium and C. difficile endospores. The doses required for inactivation of endospores were significantly higher than those required for inactivation of B. cereus and C. difficile vegetative cells, where ca 4‐log10 CFU mL?1 reductions were achieved after exposure to doses of 108 and 48 J cm?2, respectively. The significant increase in dose required for inactivation of endospores compared with vegetative cells is unsurprising due to the notorious resilience of these microbial structures. However, the demonstration that visible light of 405 nm can induce a bactericidal effect against endospores is significant, and could have potential for incorporation into decontamination methods for the removal of bacterial contamination including endospores. 相似文献
60.
Th electromagnetic field produced by a magnetic dipole in thepresence of a perfectly conducting cone of arbitrary cross-sectionis determined. The solution is used to find out how a currenton the cone travelling towards the apex is reflected. Some valuesof the reflection coefficient are calculated. In particular,it is shown that there is a sort of resonance with the reflectionincreasing significantly as the cone approaches a plane. 相似文献