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31.
Thermoplastic extrusion—the mechanism of the formation of extrudate structure and properties 总被引:6,自引:0,他引:6
Vladimir B. Tolstoguzov 《Journal of the American Oil Chemists' Society》1993,70(4):417-424
Systems processed by thermoplastic extrusion can be regarded as heterophase polymer melts of incompatible water-plasticized
biopolymers. In the process of thermoplastic extrusion, proteins and polysaccharides are melted at high pressure and temperature
below the temperature region of their thermal decomposition. Dispersed particles of these systems can be deformed in flow.
The mixed-melt anisotropic structure, formed in flow, is fixed by rapid conversion of the melt jet that lets the extruder
die from a viscous state to a rubber-like state and then to a glassy state caused by cooling and drying. Incompatibility of
proteins and polysaccharides in their water-plasticized melt mixtures impacts on structure formation and texturization during
thermoplastic extrusion.
Presented at the 20th ISF World Congress and 83rd AOCS Annual Meeting and Expo, May 10–14, 1992, Toronto, Ontario, Canada. 相似文献
32.
An experimental study of the self-diffusion and nuclear magnetic relaxation of poly(amidoamine) dendrimers with hydroxyl surface groups (PAMAM-OH) dissolved in methanol over a wide range of concentration (?) is reported. It is shown that experimental concentration dependences of PAMAM-OH self-diffusion coefficients (D) can be reduced to the so-called generalized ? dependence. Over macromolecular concentration range studied, the generalized concentration dependence of PAMAM-OH D coincides with analogous curve obtained for poly(allylcarbosilane) dendrimers of high generations. This result confirms the existence of common regularities of the dendritic macromolecule self-diffusion, and their independence of the individual physicochemical and structural properties of dendrimer, solvent, and features of their interactions in the given systems. The concentration dependence of the PAMAM-OH diffusion also exhibits a clear signature of an inflexible molecule. 相似文献
33.
34.
Vadim S. Mikulich Alexander A. Muravsky Anatoli A. Murauski Iryna N. Kukhta Vladimir E. Agabekov Rashid Altamimi 《Journal of the Society for Information Display》2014,22(1):29-34
There are many photoaligned azo dyes that can be used for orientation of liquid crystals in various display devices. However, the structure of these compounds needs to be optimized to increase the rate of the process of molecule photoalignment, as well as to spread the application of these compounds. The main coordination metal that presents in the molecules of azo dyes is sodium derivatives. The use of other alkali metals remains an open question. We used quantum‐chemical computation methods and reversible intermolecular bonding model to determine the effect of metal coordination on the velocity of photoalignment. The theoretical predictions were experimentally verified using sodium, potassium, lithium, and cesium salts of the model azo dye synthesized by us. We conclude that potassium azo derivatives are the fastest, ceteris paribus. 相似文献
35.
VladimirV.Primachenko ValeriyV.Martynenko 《中国耐火材料》2003,12(3):25-29
The article gives an introduction to the Ukrainian Research Institute of Refractories and especially its R D and refractory products for the industries of iron and steel,nonferrous,glass and chemistry etc. 相似文献
36.
Bernhard Blümich Vladimir Anferov Sophia Anferova Martin Klein Radu Fechete 《大分子材料与工程》2003,288(4):312-317
A special unilateral NMR sensor has been designed for investigations of thin samples with a thickness of less than 1 mm and of surface effects of polymers. For use with the bar‐magnet NMR‐MOUSE®, the so‐called “crazy coil” is introduced with a low penetration depth. It is a flat meander coil etched on a printed circuit board with wiggles in the conductors. The design of the new coil and FEM simulations of the B 1 field are presented. Different applications are discussed by means of illustrative examples. They are the detection of surface damage in rubber samples, the swelling and drying of a latex membrane exposed to cyclohexane vapor mimicking a chemical sensor, and the drying of a thin sprayed adhesive layer.
37.
Vladimir A. Tyurin Gianfranca Carta Yulia Y. Tyurina Sebastiano Banni Billy W. Day Francesco P. Corongiu Valerian E. Kagan 《Lipids》1997,32(2):131-142
Recent studies provide extensive evidence for the importance of carotenoids in protecting against oxidative stress associated
with a number of diseases. In particular, reactions of carotenoids with phenoxyl radicals generated by peroxidasecatalyzed
one-electron metabolism of phenolic compounds may represent an important antioxidant function of carotenoids. To further our
understanding of the antioxidant mechanisms of carotenoids, we used in the present work two different phenolic compounds,
phenol and a polar homologue of vitamin E (2,2,5,7,8-pentamethyl-6-hydroxychromane, PMC), as representatives of two different
types of phenols to study reactions of their respective phenoxyl radicals with carotenoids in cells and in model systems.
We found that phenoxyl radicals of PMC did not oxidize β-carotene in either HL-60 cells or in model systems with horseradish
peroxidase (HRP)/H2O2. In contrast, the phenoxyl radicals generated from phenol (by native myeloperoxidase in HL-60 cells or HRP/H2O2 in model systems) effectively oxidized β-carotene and other carotenoids (canthaxanthin, lutein, lycopene). One-electron reduction
of the phenoxyl radical by ascorbate (assayed by electron spin resonance-detectable formation of semidehydroascorbyl radicals)
prevented HRP/H2O2-induced oxidation of β-carotene. PMC, but not phenol, protected β-carotene against oxidation induced by a lipid-soluble azo-initiator
of peroxyl radicals. No adducts of peroxidase/phenol/H2O2-induced β-carotene oxidation intermediates with phenol were detected by high-performance liquid chromatography-mass spectrometry
analysis of the reaction mixture. Since carotenoids are essential constituents of the antioxidant defenses in cells and biological
fluids, their depletion through the reaction with phenoxyl radicals formed from endogenous, nutritional and environmental
phenolics, as well as phenolic drugs, may be an important factor in the development of oxidative stress. 相似文献
38.
Using one of the generic models (CO oxidation on Pt with surface-oxide formation) predicting kinetic oscillations in heterogeneous catalytic reactions, we show that the efficiency of two-variable periodic perturbations with respect to converting natural period-1 oscillations to period-l oscillations at the forcing frequency is remarkably sensitive to the kind of perturbations used. Counter-phase perturbations are much more effective compared to in-phase perturbations. The physics underlying these findings is suggestive of their applicability to many other models and/or real systems exhibiting kinetic oscillations. 相似文献
39.
A glassceramic material, which can be used in stomatology for production of dentinal layer of the dental crown multilayer coating, was received. In order to colour the material the admixtures of Tb and Ce compounds were used, as well as composite admixture representing a mixture of Ce, Nd and La oxides. It was demonstrated that the admixture of Tb oxide tones the material only when it is used together with Ce oxide. It was found that the more admixtures of rare earth elements oxides are contained in the sample composition, the higher the colour strength of the sintered material is. The wave length for the test samples is in the range of 600~650 nm, which corresponds to the yellow-orange and orange-red spectral range. 相似文献
40.
The diffusion of 57 Co isotope on the MgO (100) surface was investigated by the edge-source method. The surface diffusion parameter, αDs δ, where α is the segregation factor, Ds the surface diffusion coefficient, and δ the thickness of the high-diffusivity layer, was determined over the temperature region 750° to 1250°C. An Arrhenius plot shows a break at ∼1100°C. Below this temperature ionic or localized transport predominates and above it nonlocalized transport seems to predominate. The divalent Co ion diffuses faster than the trivalent Cr ion in the surface layer. The apparent activation energies for the localized surface diffusion of 57 Co and 59 Cr are 59±12 and 110±12 kj/mol, respectively. 相似文献