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131.
132.
It is observed that the harmonic balance (HB) method of parametric identification of nonlinear system may not give right identification
results for a single test data. A multiple-trial HB scheme is suggested to obtain improved results in the identification,
compared with a single sample test. Several independent tests are conducted by subjecting the system to a range of harmonic
excitations. The individual data sets are combined to obtain the matrix for inversion. This leads to the mean square error
minimization of the entire set of periodic orbits. It is shown that the combination of independent test data gives correct
results even in the case where the individual data sets give wrong results. 相似文献
133.
Three formulations for the problem of an elastica adhering to a rigid surface are discussed and compared. These include stationary principles, the surface integral of Eshelby’s energy-momentum tensor, and the material (configurational) force balance. The configuration at static equilibrium is predicted in closed form for a pair of structures that arise in nano- and microscale applications. 相似文献
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136.
The theory of long-term damage of homogeneous materials is generalized to particulate composite materials. The damage of the
composite components is modeled by randomly dispersed micropores. The damage criterion for a microvolume is characterized
by its stress-rupture strength. It is determined by the dependence of the time to brittle failure on the difference between
the equivalent stress and its limit, which is the tensile strength, according to the Huber-Mises criterion, and assumed to
be a random function of coordinates. An equation of damage (porosity) balance in the composite components at an arbitrary
time is formulated. Algorithms of calculating the time dependence of microdamage and macrostresses or macrostrains are developed
and corresponding curves are plotted in the case of limited microdurability
Translated from Prikladnaya Mekhanika, Vol. 44, No. 10, pp. 3–12, October 2008. 相似文献
137.
Bin Wan Terry A.Ring 《中国颗粒学报》2006,4(5):243-249
For many processes of industrial significance, due to the strong coupling between particle interactions and fluid dynamics, the population balance must be solved as part of a computational fluid dynamics (CFD) simulation. In this work, a CFD based population balance model is tested using a batch crystallization reactor. In this CFD model, the population balance is solved by the standard method of moments (SMOM) and the quadrature method of moments (QMOM). The results of these simulations are compared to analytical solutions for the population balance in a batch tank where 1) nucleation, 2) growth, 3) aggregation, and 4) breakage are taking place separately. The results of these comparisons show that the first 6 moments of the population balance are accurately predicted for nucleation, growth, aggregation and breakage at all times. 相似文献
138.
A so-called “interaction-box” formalism, which has recently been introduced to describe hysteresis in dynamical systems in the case of higher harmonic generation, is further discussed and generalized to describe the phenomenon of subharmonic generation. In this case, the increase in the periodicity of the response is reflected in the formation of multiple loops in the Effect (output) vs. Cause (input) diagrams. Conversely, we show how this type of response represents a sort of “signature” of the system, and can thus be employed to draw general conclusions about the features of the latter. A specific example of a nonlinear system is chosen to illustrate the approach, namely a vibrating cantilever beam with a breathing crack. Effect vs. Cause curves are calculated for this system in the presence of higher harmonics and subharmonics. 相似文献
139.
为了掌握线路的振动状态,确定线路抗振能力,保证线路安全,需要明确架空输电导线的风致振动响应.本文针对江苏境内某特高压工程LGJ-630/45型导线,建立其振动控制能量平衡方程,编制了Fortran程序以高效准确地求解该超越方程,计算分析了单导线及四种分裂导线微风振动状态下的振动及耗能特性.结果表明,单导线在风振平衡点处的双振幅最大值在最低频率上,约为导线直径的两倍;四种分裂导线风振平衡点处的幅值在15Hz附近达到最大值;导线单位长度功耗在60Hz附近达到最高,功耗能力在较低频域(10Hz~20Hz)上较弱,在较高频域(30Hz~80Hz)较强;导线分裂数越大,分裂导线的振幅越小,八分裂导线的防振消振效果相对最好;四种分裂导线在在10Hz~20Hz频域振动幅值大而单位功耗水平低,因此10Hz~20Hz频段是分裂导线的危险频段,防振措施应该针对这一频段设置.研究方法与成果为LGJ-630/45导线的抗振设计提供了科学依据. 相似文献
140.