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31.
文中以强化低温固体界面间的接触导热为出发点 ,实验测定了低温环境下两种金属界面在过度加载前后的接触热导值 ,指出过度加载是一种经济有效的强化导热方法 ,对卸载过程接触热导率大于同次加载过程接触热导的“hysteresis”现象产生机理进行了分析 相似文献
32.
Asha K. Nadipuram 《Tetrahedron letters》2006,47(3):353-356
The thermolysis of 1,2-dialkynylimidazoles in benzene solution affords high yields of 7-phenyl-5H-cyclopentapyrazines, which presumably form by solvent trapping of cyclopentapyrazine carbene intermediates. In cases where dialkynylimidazole contains side chains that can participate in intramolecular carbene C-H insertion or olefin addition, these processes compete with solvent addition to afford novel tri- and tetracyclic pyrazines, which can be obtained in good yield when the thermolysis is carried out in hexafluorobenzene. 相似文献
33.
Summary Thermopiezoelastic materials have recently attracted considerable attention because of their potential use in intelligent
or smart structural systems. The governing equations of a thermopiezoelastic medium are more complex due to the intrinsic
coupling effects that take place among mechanical, electrical and thermal fields. In this analysis, we deal with the problem
of a crack in a semi-infinite, transversely isotropic, thermopiezoelastic material by means of potential functions and Fourier
transforms under steady heat-flux loading conditions. The problem is reduced to a singular integral equation that is solved.
The thermal stress intensity factor for a crack situated in a cadmium selenide material is calculated.
Received 20 March 2001; accepted for publication 18 October 2001 相似文献
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For the methylsilsesquioxane film whose optical birefringence is almost zero, it was recently reported that its vertical thermal expansion coefficient (CTE) was approximately one order of magnitude larger than the lateral CTE. Though the birefringence is not an absolute predictor of anisotropic behavior, the discrepancy in both the CTEs was so remarkable that it was essential to investigate whether the anisotropy was intrinsic property or not. If the effect of Poisson's ratio is considered in the calculation of the vertical CTE and when elastic modulus measured by surface acoustic wave spectroscopy is used in the assessment of the lateral CTE, both the CTEs are coincident with each other. Therefore, it can be concluded that the discrepancy in the CTEs can be attributed to a higher in‐plane polymer chain orientation but it can also arise from the misleadingly assumed modulus and Poisson's ratio. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3109–3120, 2006 相似文献
37.
Quantitative x-ray diffraction topography techniques have been used to measure the residual strain magnitude and uniformity
of deposition for Mo and W sputtered films on Si(100) substrates. High sensitivity rocking curve measurements were able to
determine differential strains for films as thin as 2.5 nm; while Bragg angle contour mapping had similar sensitivity and
was also able to assess coating uniformity and stress distribution over areas covering a whole wafer. Measurements of strain
versus film thickness over a range of 2.5 nm to 80 nm showed that a critical thickness exists for maximum residual strain.
Growth beyond this range produces stress relaxation. This non-destructive type of analysis could be employed on a wide range
of film-substrate combinations. 相似文献
38.
It is thought that the extensive industrial use of arsenic, gallium and indium, which have applications as the materials for III–V semiconductors, will increase human exposure to these compounds in the near future. We have undertaken the development of new biological indicators for assessing exposure to these elements. Element-specific alterations in protein synthesis patterns were expected to occur following exposure to arsenic compounds. We examined alterations in protein synthesis in primary cultures of rat kidney proximal tubule epithelial cells by sodium arsenite, gallium chloride and indium chloride, utilizing two-dimensional gel electrophoresis. After incubation with the chemicals for 20 h, newly synthesized proteins were labeled with [35S]methionine. A protein with a molecular weight (Mr) of 30 000 was markedly induced on exposure to 10 μM arsenite or 300 μM gallium chloride, and synthesis of proteins with Mr values of 85 000, 71 000, 65 000, 51 000, 38 000 and 28 000 were also increased by exposure to arsenite and gallium chloride. No significant changes were observed upon exposure to indium. Some of these increased proteins could be heat-shock proteins. 相似文献
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The growth of Ge and SiGe alloy films on Si substrates has attracted considerable interest in the last years because of their importance for optoelectronic devices as well as Si-based high speed transistors. Here we give a short overview on our recent real time stress measurements of Ge and SiGe alloy films on Si(0 0 1) performed with a sensitive cantilever beam technique and accompanied by structural investigations with atomic force microscopy. Characteristic features in the stress curves provide detailed insight into the development and relief of the misfit strain. For the Stranski–Krastanow system Ge/Si(0 0 1) as well as for SiGe films with Si contents below 20%, the strain relaxation proceeds mainly into two steps: (i) by the formation of 3D islands on top of the Ge wetting layer; (ii) via misfit dislocations in larger 3D islands and upon their percolation. 相似文献