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991.
Summary Citric and ascorbic acids delayed substantially the rate of peroxide accumulation, during the induction period, of lard which
contained pro-oxidant levels ofα-tocopherol or NDGA. While low levels (.025%) of both acids showed effective synergistic action withα-tocopherol, higher levels were proportionately less effective.
Tocopherol had a marked protective effect on ascorbic and phosphoric acids in autoxidizing lard.
Evidence indicates that ascorbic and citric acid function as synergists in natural fats and oils by inhibiting the antioxidant
catalysis of peroxide decomposition. This concept is discussed in relation to current theories of the mechanism of synergist
action.
Journal Paper No. 742 of the Purdue University Agricultural Experiment Station, Lafayette, Ind. 相似文献
992.
Kinetics of Edible Oil Hydrogenation and Comparison of Different Catalysts The kinetics of selective hydrogenation of edible oils were investigated giving special consideration to geometrical isomerization. The reaction was carried out in a stirred semibatch pressure vessel under constant hydrogen pressure and isothermal conditions. Tests with different catalysts such as nickel, palladium, platinum, rhodium and copper chromite showed considerable differences in selectivity and isomerization behaviour. It could be shown that the major part of the elaidic acid (trans) is formed during the saturation of the linoleic acid to the monoenoic acid. Kinetic measurements with the system soybean oil/copper chromite showed that the hydrogen pressure has the biggest effect on selectivity and isomer distribution. All observed phenomena of the hydrogenation system could be described using a modified Langmuir-Hinshelwood type model. Using this model, observed conversion curves for different oils like rape seed, olive, soybean, sunflower seed and thistle oil could be simulated with good accuracy. 相似文献
993.
Norman S. Allen Kenneth O. Fatinikun A.Keith Davies Barry J. Parsons Glyn O. Phillips 《Dyes and Pigments》1981,2(3):219-229
The photofading of two anthraquinone dyes has been studied in aqueous solution using ultraviolet-visible absorption spectroscopy and flash photolysis. The influence of alcohol concentration, pH, atmosphere, photosensitisers and stabilisers have been examined and these lead to some important conclusions on the mechanism of dye fading. Essentially, the results indicate the photoexcited triplet state of the dye undergoes a process of either electron or hydrogen-atom abstraction depending on the nature of the environment. Other factors such as aggregation and singlet oxygen also appear to play an important role in solution photofading. The relevance of these results to photofading in a polymeric phase is discussed. 相似文献
994.
P. H. Eaves J. J. Spadaro E. L. D’Aquin A. J. Crovetto V. O. Cirino Mack F. Stansbury C. L. Hoffpauir 《Journal of the American Oil Chemists' Society》1956,33(12):639-645
Summary and Conclusions Crude lipides fractions were produced from raw, tempered, and cooked meats from two lots of cottonseed by a series of successive
stepwise extractions, designed to obtain fractional portions of the total lipides in the order of the difficulty of their
extraction. The proximate composition of the crude lipides fractions was determined. It was found that the composition of
successive lipides fractions varied with the degree of exhaustiveness of extraction. The fractions obtained by more exhaustive
extraction contained greater amounts of undesirable non-neutral oil material and lesser amounts of desirable neutral oil.
It was also established that the method used in preparing meats for extraction was of paramount importance in its effect on
the composition of the crude lipides obtained. The crude lipides fractions from raw and tempered meats contained large amounts
of impurities while the crude lipides fractions similarly obtained from cooked meats were relatively low in impurities.
Crude oils equivalent to varying degrees of total lipides extraction were reconstituted from the crude lipides fractions and
evaluated for refining characteristics. The impurities content of the reconstituted oils varied as the degree of total lipides
extraction and increases in the impurities content of the oils were generally reflected in disproportionate increases in refining
losses and/or refined oil color. The oils obtained from the cooked meats at all degrees of extraction were outstandingly low
in refining losses as compared to the oils from the raw and the tempered meats.
Presented in two parts at the spring meeting, American Oil Chemists’ Society, New Orleans. La., Apr. 18–20, 1955, and at the
fall meeting, Philadelphia, Pa., Oct. 10–12, 1995.
One of the laboratories of the Southern Utilization Research Branch, Agricultural Research Service, U. S. Department of Agriculture. 相似文献
995.
An optimization strategy has been applied to describe the chemical composition at the furnace bottom in the Kraft recovery boiler of a pulp production process. The concentrations of each involved chemical species were calculated through an optimization approach, minimizing the Gibbs free energy of the system. Various systems were proposed and tested, assuming different chemical species and phases number. Because serious initialization problems were found at this stage for some of the proposed systems, an optimization heuristic method (PSO) was used for the first approach to the problem. Once the appropriate phases number and chemical species in the system were determined, the initialization problems disappeared and the use of a deterministic optimization method (SQP) became viable. The proposed approach has shown to be satisfactory to reproduce industrial data and also data reported in the open scientific literature. 相似文献
996.
Fumonisin B1 is a sphingolipid-like compound that enhances the accumulation of yeast sphingolipids and 2-hydroxy fatty acids. These lipids
occur both as freely extractable and cell bound components in yeast fermentations. Both free and bound 2-hydroxy fatty acids
produced byPichia sydowiorum NRRL Y-7130 were increased when fumonisin B1 (50 mg/L) was added to the usual growth medium containing yeast extract/malt extract/peptone/glucose. Fumonisin-treated cultures
contained 38 mg/L more 2-hydroxyhexadecanoic and 15 mg/L more 2-hydroxyoctadecanoic acids than did untreated cultures. By
contrast, fumonisin inhibited the accumulation of free 8,9,13-trihydroxydocosanoic acid inRhodotorula sp. YB-2501 cultures, leading to 240 mg/L lower trihydroxy acid production than by untreated cultures. 相似文献
997.
The mandibular gland secretion of the mutillid wasp,Dasymutilla occidentalis, possesses three short-chained ketones-4-methyl-3-heptanone (4MH), 4,6-dimethyl-3-nonanone (4,6DMN), 4,6-dimethyl-3-octanone (4,6DMO)—and several unidentified compounds. This is the first report of 4,6DMN as a natural product and its synthesis is described. These ketones, which are either known to be ant alarm pheromones or are structurally very similar to ant alarm pheromones, appear to function as allomones against ants, major potential predators of mutillid wasps. The major secretory component, 4-methyl-3-heptanone, which was identified in females and/ or males of the species analyzed within the generaDasymutilla, Timulla, Traumatomutilla, andPappognatha, appears to constitute a chemical character of the defensive secretions of these genera. 相似文献
998.
999.
M. E. Iacob L. O. Meertens H. Jonkers D. A. C. Quartel L. J. M. Nieuwenhuis M. J. van Sinderen 《Software and Systems Modeling》2014,13(3):1059-1083
In this study, we argue that important IT change processes affecting an organization’s enterprise architecture are also mirrored by a change in the organization’s business model. An analysis of the business model may establish whether the architecture change has value for the business. Therefore, in order to facilitate such analyses, we propose an approach to relate enterprise models specified in ArchiMate to business models, modeled using Osterwalder’s Business Model Canvas. Our approach is accompanied by a method that supports business model-driven migration from a baseline architecture to a target architecture and is demonstrated by means of a case study. 相似文献
1000.
针对化工过程pH值变化的非线性、时滞特点,提出一种模糊免疫PID控制方法;该方法依据生物免疫原理设计免疫反馈PID控制器,并使用模糊控制器来实现免疫反馈的非线性函数,然后优化控制器的参数,最后借助MATLAB工具进行仿真实验;PID控制器比例控制由公式5计算,其参数优化结果为K=4.5,η=2.0,Ki=0.009,Kd=6.0。仿真结果显示,模糊免疫PID控制效果优于自适应模糊PID和普通PID控制的控制效果。 相似文献