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131.
A slip-line field solution is presented for the ultimate bearing capacity of the pipeline on a purely-cohesive clay soil, taking into account of circular configuration of the pipe, the pipe embedment, and the pipe-soil interfacial cohesion. The derived bearing capacity factors for a smooth rigid pipe may degenerate into those for the conventional rectangular-shaped strip footing while the pipe embedment approaches zero. Parametric studies indicate that, the pipe-soil interfacial properties have much influence on the bearing capacity for the pipe foundation on clayedy soils. 相似文献
132.
A. Gueddouh 《Phase Transitions》2017,90(10):984-1000
In this paper, spin polarization and pressure effects on the structure, magnetic and anisotropic elastic properties of the 3d transition-metal mono-borides TMB (TM = Mn, Fe) have been investigated by using generalized gradient approximation within the framework of density functional theory. It seems that manganese in MnB carries a higher magnetic moment (1.83 μB) than iron in FeB (1.12 μB). Applied pressure ranges from 0 to 150 GPa, these ferromagnetic compounds show at a certain pressure (143 GPa for MnB and 77 GPa for FeB) a pronounced abrupt collapse of the magnetic moment (first-order quantum phase transitions). Furthermore, elastic properties, including bulk, shear and Young moduli as well as the Poisson ratio are obtained by Voigt–Reuss–Hill approximation. By the elastic stability criteria, it is predicted that MnB and FeB are stable up to the selected pressures. In both cases, mechanical anisotropies are discussed by calculating different anisotropic indexes and factors. The three-dimensional surfaces and planar contours of Young, and bulk moduli of compounds are plotted, at several crystallographic planes ((100), (010) and (001)) to reveal their elastic anisotropy. 相似文献
133.
S. V. Khabirov 《Journal of Applied Mechanics and Technical Physics》2007,48(5):641-648
All partially invariant solutions in terms of the group of extensions for a model of radial motions of an ideal gas are found.
The solutions are obtained by the method of separation of variables in an equation containing functions of one variable but
different functions of different independent variables. The solutions predict different continuous unsteady convergence or
expansion of the gas under the action of a piston with a point sink or source. If the sink or source affects all particles
simultaneously, a collapse or an explosion occurs.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 5, pp. 26–34, September–October, 2007. 相似文献
134.
135.
Internal ring buckle arrestors for pipe-in-pipe systems 总被引:1,自引:0,他引:1
Erlend Olso 《International Journal of Non》2003,38(2):267-284
A new buckle arrestor concept for pipe-in-pipe systems is introduced and the results of a systematic study of its performance is presented. The concept involves either one single ring or a number of closely packed narrow rings placed in the annulus between the two pipes. Its effectiveness has been studied through a combination of experiments and analyses. The experiments involved two inch carrier tubes of three different D/t values and internal rings of various dimensions. A number of experiments were first conducted using pipe-in-pipe systems. It was found that the inner tube had only a small effect on the crossover pressure of this arrestor and, as a result, in many of the following experiments inner tubes were not included.The crossover pressure of the ring arrestors was studied by varying their length, wall thickness and yield stress. Other parameters varied were the dimensions and properties of the two tubes and the gap between the arrestor and the carrier tube. The process resulted in an empirical design formula for the arresting efficiency expressed as a function of the key nondimensional variables of the problem. Large-scale finite element models which simulate the buckle crossover process have also been developed. They have been shown capable of reproducing experiments accurately. Such models can be used to prove an arrestor design developed through the empirical process described in the report. 相似文献
136.
An experimental investigation was performed to study a specific axial crush configuration response of steel, square box components under quasi-static testing conditions. For a specific cross-sectional geometry/fabrication process, test specimens were obtained from commercially produced, welded tube lengths of ASTM A36 and ASTM A513 Type 1 plain low-carbon steels and AISI 316 and AISI 304 austenitic stainless steels. Removable grooved caps were used to constrain tube test specimen ends, and collapse initiators in the form of shallow machined grooves were used to control the initial transverse deformations of the test specimen sidewalls. The progressive plastic deformation for all of the test specimens was restricted to the prototype configuration response (fold formation process and the corresponding axial load-axial displacement curve shape) of the symmetric axial crush mode. Crush characteristics were evaluated and, for each material type, observed differences were less than 7% for maximum and minimum load magnitudes and less than 2% for energy absorption, displacement, and mean load quantities in both the initial phase and the secondary folding phase cycles. Overall, results of the study indicate that for a significant range of material strengths, a controlled and repeatable energy absorption process can be obtained for commercially produced steel box components undergoing symmetric axial crush response. 相似文献
137.
138.
地面塌陷是珠江三角洲城市地质灾害的主要类型之一。广州市主城区地面塌陷频繁发生且损失严重。采用信息量数学模型与GIS技术结合对其地面塌陷灾害进行危险性评价。选取了断裂构造、地壳稳定性、第四系覆盖层厚度、基岩岩性、地下水动力条件、地表人类活动强度和地下活动强度等7个指标中的21个变量构建了危险性评价指标体系,应用ArcGIS软件参与了数据的采集、管理、分析和评价结果表达等过程,将广州市地面塌陷灾害危险性分为极不稳定级、不稳定级、次不稳定级、基本稳定级和稳定级5个等级,极不稳定级主要分布在主城区西北角,次不稳定级分布面积最广。研究结果表明:复杂的地质环境和剧烈的人类活动相耦合,加剧了地面塌陷的发生。 相似文献
139.
140.
The formation and collapse of a vapor microcavity (microbubble) in aqueous solutions of polyacrylamide with a molecular mass of 0.5–11 million and concentration of 0–6% is studied experimentally. A microbubble less than 100 m in size is formed as a result of local superheating of the liquid by a microheater. Using stroboscopic visualization, the microbubble evolution is investigated in detail. At high polymer concentrations and low molecular masses, a slowing of bubble collapse is noted. On the range of parameters considered, no radical change in microbubble dynamics due to the action of polymeric additives was observed. 相似文献