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21.
Based on the principle of Fabry–Perot (F–P) cavity resonance and the selective permeability of gratings to specific electromagnetic waves, a graphene-based metastructure (MS) is proposed for transmissive polarization conversion (PC). Using the full-wave numerical simulation, it is found that by varying the Fermi energy of graphene, the effective resonance range of the suggested MS can be dynamically adjusted from 0.47 to 0.348–0.714 THz, achieving the target of precise to ultra-broadband polarization modulation. In this paper, the plausibility of the structure is verified from multiple perspectives, and the correlation analyses of the electric and magnetic fields are the supporting illustrations. Additionally, the triggering mechanism of PC is visually illustrated in the study of the surface currents distributions. Simulation results reveal that the MS is superior in performance, functionality, and principle, and it is foreseen to hold excellent promise for integrated equipment in the terahertz (THz) band. 相似文献
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23.
I. A. Lukovskii 《International Applied Mechanics》2004,40(10):1092-1128
A variational approach to solving linear and nonlinear problems for a body with cavities partially filled with a perfect incompressible fluid is enunciated. The approach applies a nonclassical variational principle to describe the spatial motion of a finite fluid with a free surface and the classical variational principle, which is widely used in rigid body dynamics. These principles are used to formulate variational problems that are the basis of direct methods of solving nonlinear and linear dynamic problems for body-fluid systems. The approach allows us to derive an infinite system of nonlinear ordinary differential equations describing the joint motion of the rigid body and fluid and to develop an algorithm for determining the hydrodynamic coefficients. Linearized differential equations of motion of the mechanical system are presented and approximate methods are given to solve linear boundary-value problems and to determine the hydrodynamic coefficients.Translated from Prikladnaya Mekhanika, Vol. 40, No. 10, pp. 37–77, October 2004.The study was partially sponsored by the German Research Fund (der Deutsche Forschungsgemeinschaft), Grant 436 UKR113/33/0-3. 相似文献
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25.
B. González-SantiagoV. de la Luz M.I. Coahuila-HernándezF. Rojas S.R. Tello-SolísA. Campero M.A. García-Sánchez 《Polyhedron》2011,30(7):1318-1323
An effective way of trapping phthalocyanines inside porous silica has been achieved when an aqueous solution of these macrocyclic species is reacted in situ with silicon alkoxide. The resultant porous gel network can encapsulate a myriad of metal phthalocyanine molecules at relatively high concentrations and, most importantly, in a disaggregated way. By employing this method metal sulfophthalocyanines of Fe, Co, Ni, Cu, Al, Eu or Sm can be encapsulated within SiO2 xerogels. Here, the chemical entrapment of phthalocyanines inside silica gel pore networks is accomplished by the attachment of bifunctional groups to the walls of these substrates; while one of these moieties is directly linked to the macrocycle end groups, the other one is covalently bonded to the silanol groups resting on the SiO2 walls. Furthermore, when the proper concentrations of phthalocyanine species, H2O, silicon alkoxide, and HCl are reacted together, it is possible to obtain monolithic translucent silica xerogels. This latter property provides straightforward evidence of the innate fluorescence of the trapped macrocycles. The average size of the cavities encapsulating the macrocyclic molecules range from 2.0 to 3.6 nm; the precise size depends on the cation present in the complex and on the identity and position of the substituent groups at the periphery of the macrocycle. When the silica network is prepared from standard and/or organo-substituted alkoxides, the aggregation, degradation or stability of the macrocyclic species trapped in silica cavities depends on the nature of the alkyl group attached to the pore walls. 相似文献
26.
P N Ostroumov 《Pramana》2002,59(6):895-913
The Nuclear Science Community in the Unites States has unanimously concluded that developments in both nuclear science and
its supporting technologies make building a world-leading Rare-Isotope Accelerator (RIA) facility for production of radioactive
beams the top priority. The RIA development effort involves several US Laboratories (ANL, JLAB, LBNL, MSU, ORNL). The RIA
facility includes a CW 1.4 GeV driver LINAC and a 100 MV post-accelerator both based on superconducting (SC) cavities operating
at frequencies from 48 MHz to 805 MHz. An initial acceleration in both LINACs is provided by room temperature RFQs. The driver
LINAC is designed for acceleration of any ion species; from protons up to 900 MeV to uranium up to 400 MeV/u. The novel feature
of the driver LINAC is an acceleration of multiple charge-state heavy-ion beams in order to achieve 400 kW beam power. Basic
design concepts of the driver LINAC are given. Several new conceptual solutions in beam dynamics, room temperature and SC
accelerating structures for heavy ion accelerator applications are discussed. 相似文献
27.
The single longitudinal mode (SLM) characteristics of narrow linewidth long-external-cavity semiconductor lasers has been improved significantly by using a multisegment composite-cavity configuration. In this paper, the mode selectivities of two-segment, three-segment and four-segment cavity semiconductor lasers have been analysed and compared. In experiments, a four-segment composite cavity laser exhibits SLM oscillation with side-mode suppression ratio of 30 dB even for total external cavity length of 75 cm. The oscillation linewidth is less than 200 kHz. 相似文献
28.
A theoretical model of disorder for the etched holes or pillars in a generic two-dimensional photonic crystal slab is presented. This model is employed to calculate the effects of size disorder on propagation losses in linear photonic crystal waveguides as well as on quality (Q)-factors in photonic crystal nano-cavities. The main results obtained by the present theory and shown in this work are: (a) large single-mode bandwidth and low-loss (<0.1 dB/mm) propagation of light is predicted for increased-width membrane-type photonic crystal waveguides, (b) pillar-based lattices show reduced sensitivity to size fluctuations than hole-based ones, (c) the effects of disorder on cavity Q-factors are quantitatively evaluated. An extension of the model is also introduced in order to take into account the side-wall micro-roughness of the perfectly vertical holes, and preliminary results of this more general approach are discussed. 相似文献
29.
用场方法研究了相对论速调管振荡器中两个调制腔的耦合,解析地得到了两腔耦合系数与腔和波导的尺寸、间隙及两腔之间的距离等参数之间的关系。耦合系数的数值与由耦合与否腔的频率测量确定的实验结果在数量级上符合得较好。 相似文献
30.
Direct and inverse problems of oscillations of an anisotropic layer with a cylindrical cavity of an arbitrary cross-sectional
shape under the action of a load applied to the layer surface are considered. An asymptotic approach to solving these problems
with cavities of small relative sizes is proposed. Numerical results of solving direct and inverse problems are presented.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 3, pp. 181–189, May–June, 2009. 相似文献