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81.
Strength and electrical conductivity of deformation-processed Cu-15 Vol Pct Fe alloys produced by powder metallurgy techniques 总被引:16,自引:0,他引:16
G. A. Jerman I. E. Anderson J. D. Verhoeven 《Metallurgical and Materials Transactions A》1993,24(1):35-42
Powder metallurgical techniques have been employed to prepare the precursor billets in the preparation of Cu-15 vol pct Fe
alloys by deformation processing. It has been demonstrated that by (1) using high-purity gas-atomized Cu powders blended with
commercial high-purity Fe powders and (2) controlling the time/temperature processing conditions within specific limits, it
is possible to produce Cu-Fe deformation-processed alloys with strength/conductivity properties matching those of Cu-Nb, Cu-Ta,
and Cu-Cr alloys. These properties are significantly superior to the best commercial alloys.
formerly with the Department of Materials Science and Engineering and Ames Laboratory, Iowa State University
This article is based on a presentation made in the symposium “High Performance Copper-Base Materials” as part of the 1991
TMS Annual Meeting, February 17–21, 1991, New Orleans, LA, under the auspices of the TMS Structural Materials Committee. 相似文献
82.
83.
JW Finley PE Johnson PG Reeves RA Vanderpool M Briske-Anderson 《Canadian Metallurgical Quarterly》1994,42(2):81-96
Biliary/pancreatic (B/P) secretions are a major component of endogenous secretions, and endogenously secreted Zn is a primary means of Zn homeostasis. This study examined whether B/P fluid alters the absorption/reabsorption of Zn and, in doing so, whether this contributes to homeostatic control of Zn. Animal experiments utilized rats fed 10 or 300 micrograms Zn/kg diet. An open-ended gut perfusion study in which 65Zn-labeled B/P fluid or 67Zn-labeled and digested diet found significantly decreased Zn absorption from B/P fluid. Although Zn absorption from both sources was less in animals fed diets higher in Zn, there was no interaction of treatment and diet. Further studies utilizing cultured human colon carcinoma cells (CACO-2) as in vitro models of gut enterocytes found that the presence of B/P fluid significantly decreased Zn retention and/or transport and resulted in a redistribution of cellular Zn after 1200 min of incubation. These studies show that a substance in B/P fluid can decrease the absorption of Zn and also suggest that dietary Zn and Zn associated with B/P secretions are absorbed from distinct pools. However, the lack of an interactive effect with diet, and the amount of time required to see differences in CACO-2 cells, suggest that differences in absorption are not a major contributor to Zn homeostasis. 相似文献
84.
Hobbie KA Peterson ES Barton ML Waters KM Anderson KA 《Journal of laboratory automation》2012,17(4):275-283
Large collaborative centers are a common model for accomplishing integrated environmental health research. These centers often include various types of scientific domains (e.g., chemistry, biology, bioinformatics) that are integrated to solve some of the nation's key economic or public health concerns. The Superfund Research Center (SRP) at Oregon State University (OSU) is one such center established in 2008 to study the emerging health risks of polycyclic aromatic hydrocarbons while using new technologies both in the field and laboratory. With outside collaboration at remote institutions, success for the center as a whole depends on the ability to effectively integrate data across all research projects and support cores. Therefore, the OSU SRP center developed a system that integrates environmental monitoring data with analytical chemistry data and downstream bioinformatics and statistics to enable complete "source-to-outcome" data modeling and information management. This article describes the development of this integrated information management system that includes commercial software for operational laboratory management and sample management in addition to open-source custom-built software for bioinformatics and experimental data management. 相似文献
85.
Loss of precious metals from a Pt-10 wt% Rh alloy was studied at 1300° C in refractory oxides and fused quartz environments. After 60 and 150 h annealings, samples exposed to gaseous environments showed significant weight loss. The surface was attacked and characterized by micron-sized pits, as well as river-like striations. The pits were found to be enriched with silicon and/or aluminium depending upon the heating environment. Laser Raman microprobe identified that the major compound formed in the pits is -cristobalite.Direct solid state contact of Pt-Rh with Al2O3 and SiO2 showed interactions between materials. The interaction was more extensive between Pt-Rh with SiO2 than with Al2O3. On the other hand, no evidence of interaction except pitting and striation was observed on Pt-Rh when exposed to a vapour environment.The presence of pits and striation patterns indicated that refractory oxides attacked Pt-Rh under atmospheric conditions, and gave rise to the weight loss. Calculation of weight loss by an oxidation mechanism shows one to two orders of magnitude lower value than the actual weight loss. A new loss mechanism is proposed and discussed in this article. 相似文献
86.
87.
Men and equipment in space vehicles in low earth orbit are exposed to a wide variety of radiations, but the majority of the dose is due to trapped protons, which have energies of the order of 100 MeV and are low LET particles. These high energy particles produce nuclear fragmentation with high LET secondaries that may be responsible for a significant fraction of dose equivalent. In order to understand better the biological effectiveness of this radiation environment, a portable tissue equivalent proportional counter spectrometer has been developed that automatically records the distribution of energy in a small tissue-like site as a function of time. This instrument weighs about 700 g and will be flown on a number of future space shuttle flights. 相似文献
88.
The specific heat at constant flux densityC
B
was measured to study the thermodynamic properties of the mixed state of a type II superconductor at low reduced temperaturet=T/T
c
. The sample was a Pb0.96Tl0.04 alloy having =0.97. The results are thatC
B
increases nearly linearly withB throughout the mixed state, with a discontinuous jump down to the normal state value at the upper critical field. Att<0.21 a small, positive curvature ofC
B
versusB is consistent with Eilenberger's calculations. However, this positive curvature is not consistent with fluxoid interaction models for low flux density. These measurements supplement previous measurements fort<0.5 using isothermal calorimetry on the same sample. Taken together, the two experiments indicate that, at a givenT, the incremental entropy per fluxoid is nearly constant for allB. This result forces some interesting empirical relationships among the parameters that characterize the mixed state.On sabbatical leave from South Dakota School of Mines and Technology, Rapid City, South Dakota. 相似文献
89.
90.
Hysteresis effects are reported for ZrO2 oxygen sensors exposed to non-equilibrium oxygen/hydrocarbon gas mixtures. With oxygen/toluene at 800° C, voltage-composition curves differ following composition changes (a) from excess oxygen to excess toluene and (b) from excess toluene to excess oxygen. A catalysis model is developed to account for this behaviour: the Thiele modulus of the catalyst/electrode is presumed to differ under (a) net oxidizing and (b) net reducing conditions. Large scale voltage fluctuations, sometimes exceeding 400 mV, were observed in experiments with oxygen/isobutane mixtures at 600° C. This behaviour is analysed in terms of a kinetic model involving stochastic variations of relative mass transfer coefficients of oxygen and isobutane. 相似文献