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671.
利用Born-Oppenheimer近似研究了零温时耗散两态系统的动力学特性.在不同环境谱分布下,给出了两态之间的跃迁几率随时间的变化.数值结果表明:当环境的谱分布为Ohmic形式时,跃迁几率是一个衰减的函数;而当谱分布为随机取值时,跃迁几率具有“量子跳跃”的特性.与之相对比,我们还给出了当把环境等价成无穷多个谱振子的集合时,跃迁几率随时间的变化. 相似文献
672.
Electrical conductivity and stimulated thermocurrent (stc) studies are carried out in dicalcium lead propionate (dlp) in pure, Cu2+, Fe3+ and acetate doped single crystals over a temperature range of 303° to 503° K. Conductivity measurements on pure and doped
single crystals ofdlp indicate that both propionate anions and metallic cations are responsible for the transition occurring at 333°K. Thermoelectric
power measurements from 340° to 500°K indlp (pure) indicate that the transport charge carriers are electrons. A model for the conduction mechanism is proposed on the
basis of hopping ofπ or resonating electrons of carboxyl groups through tunnel paths involving metal ions (Pb2+ and Ca2+). From activation energies estimated from conductivity andstc measurements, thestc peak indlp (Fe3+) occurring at 513°K is attributed to impurity vacancy jump mechanism. 相似文献
673.
Tianmin Dai 《中国科学A辑(英文版)》1998,41(2):211-215
Three systems of balance equations and jump conditions as well as generalized Clausius-Duhem inequalities for nonlocal polar
thermomechanical continua are naturally and systematically derived under the consideration of Euler angles as angular coordinates
and the negligence of conservation law of microinertia as well as the introduction of some new definitions. These results
are more general than those balance equations and jump conditions as well as generalized Clausius-Duhem inequalities proposed
by Eringen for nonlocal micropolar thermomechanical continua and more suitable to treat the problems of finite deformations.
Project supported by the National Natural Science Foundation of China and the Research Foundation of Liaoning Province. 相似文献
674.
A theory for the optimization of nonlinear hydraulic systems is presented. The problem has been solved in spite of the nonlinear system model and the mixed-integer nature of the decision variables. The optimization problem is formulated in terms of the time-distribution-function concept. This leads to a numerically efficient two-level algorithm. No specific control model is needed: the algorithm employs a system simulator. The general approach is also applicable to other nonlinear systems. The paper concludes with a practical application, together with numerical results.The authors would like to thank both Thames Water Authority and Yorkshire Water Authority for support and valuable discussions. The contribution from Mr. John Rance in analyzing the system is also gratefully acknowledged.on leave from Bialystok Polytechnic, Bialystok, Poland. 相似文献
675.
Stefan J. Kowalski 《Transport in Porous Media》1992,9(1-2):39-47
Two-parameter structure model of a porous solid is proposed as an approximation of a real porous structure and the macroscopic mass and momentum balance equations are derived for such a medium filled with liquid. The approach presented leads to the equations of motion for a fluid-saturated porous medium with coupling terms via cross-mass couplings. The linear form of these equations is equivalent to the well-known Biot equations. 相似文献
676.
Krystian Eitner Franz Bartl BogumiŁ Brzezinski Grzegorz Schroeder 《Supramolecular chemistry》2013,25(5):627-635
Abstract For macrocyclic bases such as: 1-aza-15-crown-5 (N15C5),1,4,10-trioxa-7,13-diazacyclopentadecan (21), 1,7,10,16-tetraoxa-4,13-diazacyclooctadecan (22) and 1, 4, 7, 13, 16-pentaoxa-10, 19-diazacycloheneicosane (23), the kinetics of deprotonation and protonation reactions in the presence of monovalent cations was studied using the temperature jump technique. For the sake of comparison, the measurements were also performed for 1,4-diazabicyclo[2,2,2]octane (DABCO) base, which does not form complexes with monovalent cations. The monovalent cations affect the temperature dependence of the kinetic parameters of deprotonation. They also affect the activation parameters, which is shown by a distribution of ΔH≠ and ΔS≠ values, but do not influence the value of ΔG≠. 相似文献
677.
Daryoush Safarzadeh Shamsuddin Sulaiman Faieza Abdul Aziz Desa Bin Ahmad Gholam Hossein Majzoobi 《Journal of Terramechanics》2011,48(2):157-168
In order to prevent the hazards associated with the crane application in workshops and factories, a self-propelled hydraulic floor crane with wire remote control was designed. The main focus was directed on remote control of the crane operations such as rotation of booms, rear and forward movements, changing travel speed, steering, braking and hook rotation. This configuration prevents the hazards and damages which may be created due to the proximity of operator to crane and provides the feasibility of utilizing the crane in crowded manufacturing areas, fields and hazardous environments. Research into the stability of crane on a slope route was also performed to obtain the equations of stability in static and dynamic conditions and recognition of the ways to enhance the stability. To validate the research work, a scale-model prototype was built to test the manner of controlling the crane operations from afar. 相似文献
678.
假设参考实体没违约时信用违约互换保护买方连续支付互换价格,导出了信用违约互换价格的表达式;对标的资产价值服从双指数跳扩散模型,得到了条件违约风险率和信用违约互换的短期价格极限.这些结果比纯扩散模型假设更符合实际. 相似文献
679.
Two fundamentally different versions of the method of multiple scales (MMS) are currently in use in the study of nonlinear resonance phenomena. While the first version is the widely used reconstitution method, the second version is proposed by Rahman and Burton [1]. Both versions of the second-order MMS are applied to the differential equation obtained for a parametrically excited cantilever beam with a lumped mass at an arbitrary position. The bifurcation and stability of the obtained response show the difference between the two versions. While the Hopf bifurcation phenomena with no jump is found in the case of second-order MMS version I, both jump-up and jump-down phenomena are observed in second-order MMS version II, which closely agree with the experimental findings. The results are compared with those obtained by numerically integrating the original temporal equation. 相似文献
680.
Matthew A. Bognar 《Computational Statistics》2008,23(3):361-379
Many analyses of continuously marked spatial point patterns assume that the density of points, with differing marks, is identical.
However, as noted in the seminal paper of Goulard et al. (Scand J Stat 23:365–379, 1996), such an assumption is not realistic
in many situations. For example, a stand of forest may have many more small trees than large, hence the model should allow
for a higher density of points with small marks. In addition, as suggested by Ogata and Tanemura (Biometrics 41:421–433, 1985),
the interaction between points should be a function of their mark, allowing, for example, the range of interaction for large
trees to exceed that of smaller trees. The aforementioned articles use frequentist inferential techniques, but interval estimation
presents difficulties due to the extremely complex distributional properties of the estimates; it might be possible, however,
to use parametric bootstrap methodology for such inferences (Baddeley et al. in J Roy Stat Soc Ser B 67:617–666, 2005). We
suggest the use of Bayesian inferential techniques. Although a Bayesian approach requires a complex, computational implementation
of (reversible jump) Markov Chain Monte Carlo methodology, it enables a wide variety of inferences (including interval estimation).
We demonstrate our approach by analyzing the well known Norway spruce dataset. 相似文献