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961.
Kihwan Kim 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(15):2579-2589
The discrete ordinates interpolation method (DOIM) is applied to three groups of problems of radiative heat transfer in three-dimensional rectangular enclosures containing non-gray or scattering medium. The original DOIM is first extended to a gray gas model using a new geometric interpolation scheme. It is applied to participating media for different scattering phase functions and optical thicknesses. For the non-gray gas model, the DOIM coupled with the narrow band-based weighted-sum-of-gray-gases (WSGG) model is developed. A few test problems with real gases such as pure H2O and a mixture of CO2, H2O and N2 are taken. The wall heat flux is calculated and compared with the exact solutions or reference values. All results of test problems are found to be reliable in this study. The DOIM closely reproduces the Monte Carlo reference solutions for different scattering phase functions and optical thicknesses. The non-gray gas results are compared with reference calculations based on the statistical narrow band model and they also show good agreements. The DOIM shows a remarkable merit in the computation time and the grid compatibility, to prove its usefulness for engineering applications. 相似文献
962.
We describe a chiral axial next nearest neighbour xy-model to account for the various subphases exhibited by antiferroelectric liquid crystals made of chiral rod-like molecules.
The assumed form of the interlayer interactions is based on physical processes which are discussed. Using a discrete model,
the predicted sequence of transitions is SmA-SmC-SmC-FIH-FII-FIL-SmC
*
A, where FI stands for a ferriphase, as seen in many compounds. The ferri and SmC phases are characterized by relatively large angles between the c-vectors of successive layers and occur only when the compounds have high optical purity. The calculated field induced structures
exhibit a plateau of the apparent tilt angle at , where is the tilt angle of the molecules in the ferriphase. The conoscopic figures in the presence of a field and ellipsometric
parameters in the absence of a field have also been generated, which agree extremely well with the experimental results. Recent
anomalous X-ray scattering studies prove the xy-character of the configurations, though the commensurate structures that are found in the ferriphase require an extension
of the model to include lock-in terms.
Received 23 August 1999 相似文献
963.
964.
Z-连续格的函数空间 总被引:1,自引:1,他引:0
若 Z为并完备的子集系统 ,且 IZ( L)关于集合的包含关系构成完备格 ,则 :( 1 ) Z-连续格的函数空间仍为 Z-连续的 ;( 2 )对于 Z-连续格范畴 ZL ,定义了一函子 F:ZL× ZL→ ZL. 相似文献
965.
966.
G. Albinet L. Raymond 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,13(3):561-569
Powdered solids often present very specific properties due to their granular nature. Such powders are often obtained by mixing
two ingredients in variable proportions: conductor and insulator, or conductor and super-conductor. In a very natural way,
these systems are modeled by regular lattices, whose sites or bonds are randomly chosen with given probabilities. It is known
that the electrical and optical properties of random bi-dimensional (2D) networks are well described by their conductance's
poles (resonances) and residues (amplitudes). The numerical implementation of a spectral method gave the spectral density,
the AC conductivity, the multi-fractal properties of the moments for the local electric field (or currents), and spectrum
of resonances characteristic of some small clusters (animals). This work extends the spectral method to the three-dimensional
(3D) case where the problem is more complicated because the duality property and the corresponding symmetries are broken.
As in the 2D-case, the two significant parameters are the ratio of the complex conductances and of both phases, and the probability p (resp. 1-p) of (resp. ). All the resonances lie on the negative real h-axis, i.e. for pure non resistive networks in the AC case. For a static (DC) system, only the value h=0 (corresponding to a binary system with finite and , or and finite) can give a resonance. Some applications are proposed, in particular the ability for small clusters (animals with one,
two or three bonds) to present a singular response for well identified frequencies of the incident electromagnetic field.
Received 24 March 1999 相似文献
967.
S.T. Hyde C. Oguey 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,16(4):613-630
A method is developed to construct and analyse a wide class of graphs embedded in Euclidean 3D space, including multiply-connected
and entangled examples. The graphs are derived via embeddings of infinite families of trees (forests) in the hyperbolic plane, and subsequent folding into triply periodic minimal
surfaces, including the P, D, gyroid and H surfaces. Some of these graphs are natural generalisations of bicontinuous topologies to bi-, tri-, quadra- and octa-continuous
forms. Interwoven layer graphs and periodic sets of finite clusters also emerge from the algorithm. Many of the graphs are
chiral. The generated graphs are compared with some organo-metallic molecular crystals with multiple frameworks and molecular
mesophases found in copolymer melts.
Received 10 December 1999 相似文献
968.
Geng Xiangyi 《东北数学》1999,(1)
Undertheopensetcondition,aninequalityonthebox-countingdimensionofinvari-antsetsforcontractioniteratedfunctionsystemsweregiven... 相似文献
969.
高校应用数学学报 《高校应用数学学报(A辑)》1999,14(1):22
如果一个Hopfield神经网络系统(以下简记为HNNS)是时间离散、状态连续的,就称之为时间离散的HNNS(以下简记为TD-HNNS).对这种系统,如果在它的算子的作用下,状态的能量函数具有固定的增、减趋势,那么就称之为单向的TD-HNNS.本文讨论并给出了这种模型的一系列性质,如运动轨迹的稳定性、收敛性和稳定解的唯一性等,并由此给出了它在优化计算中的一系列应用. 相似文献
970.