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81.
针对广州开发区SDK-D-2地块砌石挡土墙软弱地层,采用单液静力注浆进行灌浆加固。详细论述了灌浆处理工程中的材料及工艺设备、工艺参数、工艺流程,异常情况技术处理及检测措施,分析了灌浆效果。实践表明处理方法有效,达到了工程设计标准。 相似文献
82.
83.
Effects of precipitated silica (PSi) and silica from fly ash (FA) particles (FASi) on the cure and mechanical properties before and after thermal and oil aging of natural rubber (NR) and acrylonitrile–butadiene rubber (NBR) blends with and without chloroprene rubber (CR) or epoxidized NR (ENR) as a compatibilizer have been reported in this paper. The experimental results suggested that the scorch and cure times decreased with the addition of silica and the compound viscosity increased on increasing the silica content. The mechanical properties for PSi filled NR/NBR vulcanizates were greater than those for FASi filled NR/NBR vulcanizates in all cases. The PSi could be used for reinforcing the NR/NBR vulcanizates while the silica from FA was regarded as a semi‐reinforcing and/or extending filler. The incorporation of CR or ENR enhanced the mechanical properties of the NR/NBR vulcanizates, the ENR being more effective and compatible with the blend. The mechanical properties of the NR/NBR vulcanizates were improved by post‐curing effect from thermal aging but deteriorated by the oil aging. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
84.
The problem on large deformations of round cylinders made of homogeneous and fiber-reinforced elastomeric materials under
the action of inertia forces caused by rotatory motion is solved. The solution is given in a plane axisymmetric statement,
where the deformation parameters of the cylinders depend only on the radial coordinate. Based on the mathematical model presented,
the deformation of revolving cylinders made of homogeneous elastomeric materials and reinforced with fibers in the axial,
circumferential, and radial directions is investigated. The ultimate rotational speeds for cylinders with different reinforcement
schemes and tight and loose fits are found at which their limiting configurations are reached.
Translated from Mekhanika Kompozitnykh Materialov, Vol. 45, No. 3, pp. 347-366, May-June, 2009. 相似文献
85.
Prediction of near field overpressure from quarry blasting 总被引:1,自引:0,他引:1
This paper investigates the propagation of airblast or pressure waves in air produced by bench blasting (i.e. detonation of the explosive in a row of blastholes, breaking the burden of rock towards the free vertical face of the block). Peak overpressure is calculated as a function of blasting parameters (explosive mass per delay and velocity at which the detonation sequence proceeds along the bench) and the polar coordinates of the position of interest (distance to the source and azimuth with respect to the free face). The model has been fitted to empirical data using linear least squares. The data set is composed of 122 airblast records monitored at distances less than 400 m in 41 production blasts carried out in two quarries. The model is statistically significant and has a determination coefficient of 0.87. The formula is validated from 12 airblast measurements gathered in five additional blasts. 相似文献
86.
S. Abramchuk E. Kramarenko D. Grishin G. Stepanov L. V. Nikitin G. Filipcsei A. R. Khokhlov M. Zrínyi 《先进技术聚合物》2007,18(7):513-518
The combination of polymers with magnetic particles displays novel and often enhanced properties compared to the traditional materials. They can open up possibilities for new technological applications. The magnetic field sensitive elastomers represent a new type of composites consisting of small particles, usually from nanometer range to micron range, dispersed in a highly elastic polymeric matrix. In this paper, we show that in the presence of built‐in magnetic particles it is possible to tune the elastic modulus by an external magnetic field. We propose a phenomenological equation to describe the effect of the external magnetic field on the elastic modulus. We demonstrate the engineering potential of new materials on the examples of two devices. The first one is a new type of seals fundamentally different from those used before. In the simplest case, the sealing assembly includes a magnetoelastic strip and a permanent magnet. They attract due to the magnetic forces. This ensures that due to high elasticity of the proposed composites and good adhesion properties, the strip of magnetoelastic will adopt the shape of the surface to be sealed, this fact leading to an excellent sealing. Another straightforward application of the magnetic composites is based on their magnetic field dependent elastic modulus. Namely, we demonstrate in this paper the possible application of these materials as adjustable vibration dampers. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
87.
Mohammed A. Sharaf Andrzej Kloczkowski Taner Z. Sen Karl I. Jacob James E. Mark 《Colloid and polymer science》2006,284(7):700-709
The effects of the oriented fiber filler particles on the microscopic properties of the matrix network chains were investigated by using nanofiber filler particles as reinforcing material. Monte Carlo Rotational Isomeric State simulations were carried out for filled poly(ethylene) (PE) networks to study the dependence of the conformational distribution functions of polymer chains and their elastomeric properties on filler loadings. We were especially interested how the excluded volume effect of the nanofiber particles and their orientation (specifically orientational anisotropy) in the matrix influence elastomeric properties of the network. Distribution functions of the end-to-end distances of polymer chains for both unfilled and filled networks were calculated. Effects of nanofiber reinforcements with varying fiber radii and fiber volume fractions were investigated. We have found that the presence of nanofibers significantly increase the non-Gaussian behavior of polymer chains in the composite. The anisotropic effects of the nanofibers on mechanical properties of polymeric composites were studied as a function of their relative orientation to the direction of deformation. The modulus (reduced nominal stress per unit strain) was calculated from the distribution of end-to-end distances of polymer chains using the Mark–Curro method. Relatively small amount of nanofibers was found to increase the normalized moduli of the composite. Our results are quite in satisfactory qualitative agreement with experimental data reported in the literature. This shows that computer simulations provide a powerful tool in predicting physical properties of composite materials. 相似文献
88.
Kaifang Wan Dingwei Wu Yiwei Zhai Bo Li Xiaoguang Gao Zijian Hu 《Entropy (Basel, Switzerland)》2021,23(11)
A pursuit–evasion game is a classical maneuver confrontation problem in the multi-agent systems (MASs) domain. An online decision technique based on deep reinforcement learning (DRL) was developed in this paper to address the problem of environment sensing and decision-making in pursuit–evasion games. A control-oriented framework developed from the DRL-based multi-agent deep deterministic policy gradient (MADDPG) algorithm was built to implement multi-agent cooperative decision-making to overcome the limitation of the tedious state variables required for the traditionally complicated modeling process. To address the effects of errors between a model and a real scenario, this paper introduces adversarial disturbances. It also proposes a novel adversarial attack trick and adversarial learning MADDPG (A2-MADDPG) algorithm. By introducing an adversarial attack trick for the agents themselves, uncertainties of the real world are modeled, thereby optimizing robust training. During the training process, adversarial learning was incorporated into our algorithm to preprocess the actions of multiple agents, which enabled them to properly respond to uncertain dynamic changes in MASs. Experimental results verified that the proposed approach provides superior performance and effectiveness for pursuers and evaders, and both can learn the corresponding confrontational strategy during training. 相似文献
89.
Ultrahigh molecular weight polyethylene (UHMW-PE) has been grafted with acrylonitrile using gamma radiation. The graft yield of the monomer was controlled by the proper choice of radiation dose and monomer concentration. The grafted chopped fibers were introduced in polychloroprene (CR) rubber mixes in order to improve the interfacial adhesion between fibers and matrix. It has been found that the improvement in the mechanical properties of rubber composites obtained depended markedly on the fiber concentration in the rubber mixture. Scanning electron micrographs showed the presence of a continuous phase of rubber adhered to the surface of grafted fiber. © 1997 John Wiley & Sons, Ltd. 相似文献
90.
This paper presents experimental results from an analysis of two similar games, the repeated ultimatum game and the repeated
best-shot game. The experiment examines whether the amount and content of information given to players affects the evolution
of play in the two games. In one experimental treatment, subjects in both games observe not only their own actions and payoffs,
but also those of one randomly chosen pair of players in the just-completed round of play. In the other treatment, subjects
in both games observe only their own actions and payoffs. We present evidence suggesting that observation of other players'
actions and payoffs may affect the evolution of play relative to the case of no observation.
Received February 1996/Final version April 1998 相似文献