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991.
3,4-亚甲二氧基苯乙胺的合成新方法 总被引:1,自引:0,他引:1
以胡椒胺为原料,通过Sandmeyer反应制得3,4-亚甲二氧基溴苯(收率75.0%),再经Grignard反应(收率74.8%)、酯化反应(收率94.0%)和Gabriel反应(收率63.0%)制备出3,4-亚甲二氧基苯乙胺,并通过红外光谱和色谱-质谱联用确定了目标产物的结构。讨论温度对各步反应的影响,确定了最佳反应条件。 相似文献
992.
Stakheev A. Yu. Gabrielsson P. Gekas I. Teleguina N. S. Bragina G. O. Tolkachev N. N. Baeva G. N. 《Topics in Catalysis》2007,42(1-4):143-147
Pt/Al2O3 and Pt/BaO/Al2O3 catalysts (1 wt% Pt, 10 wt%BaO) were sulfated under conditions simulating a real NSR catalyst operation. Comparative TPR
and XPS studies of sulfur removal from Pt/Al2O3 and Pt/BaO/Al2O3 catalysts indicate that the sulfur removal from Al2O3 surface precedes reductive decomposition of BaSO4 (250–400 °C). Barium sulfate decomposition started with further increase in desulfation temperature at the point of surface
atomic ratio Ba:S = 1 (~450o). Simultaneously, an intensive formation of sulfide species on the catalyst surface was observed. Thermodynamic analysis
of the desulfation process allows us to hypothesize that barium sulfide formation may hinder sulfur removal under reducing
conditions. 相似文献
993.
Saleh Al-Sayari Albert F. Carley Stuart H. Taylor Graham J. Hutchings 《Topics in Catalysis》2007,44(1-2):123-128
The preparation of Au/ZnO and Au/Fe2O3 catalysts using two coprecipitation methods is investigated to determine the important factors that control the synthesis
of high activity catalysts for the oxidation of carbon monoxide at ambient temperature. In particular, the factors involved
in the preparation of catalysts that are active without the need for a calcination step are evaluated. The two preparation
methods differ in the manner in which the pH is controlled during the precipitation, either constant pH throughout or variable
pH in which the pH is raised from an initial low value to a defined end point. Non-calcined Au/ZnO catalysts prepared using
both methods are very sensitive to pH and ageing time, and catalysts prepared at a maximum pH = 5 with a short ageing time
(ca. 0–3 h) exhibit high activity. Catalysts prepared at higher pH give lower activity. However, all catalysts require a short
operation period during which the oxidation activity increases. In contrast, the calcined catalysts are not particularly sensitive
to the preparation conditions. Non-calcined Au/Fe2O3 catalysts exhibit high activity when prepared at pH ≥ 5. Calcined Au/Fe2O3 prepared using the controlled pH method retain high activity, whereas calcined catalysts prepared using the variable pH method
are inactive. The study shows the immense sensitivity of the catalyst performance to the preparation methods. It is therefore
not surprising that marked differences in the performance of supported Au catalysts for CO oxidation that are apparent in
the extensive literature on this subject, particularly the effect of calcination, can be expected if the preparation parameters
are not carefully controlled and reported. 相似文献
994.
Yu Zhang Xiaomin Dou Jian Liu Min Yang Liping Zhang Yoichi Kamagata 《Catalysis Today》2007,126(3-4):387-393
Decolorization of reactive brilliant red X-3B was studied by using an Fe–Ce oxide hydrate as the heterogeneous catalyst in the presence of H2O2 and UV. The decolorization rate was in the order of UV–Fe–Ce–H2O2 > UV–Fe3+–H2O2 > UV–H2O2 > UV–Fe–Ce ≥ Fe–Ce–H2O2 > Fe–Ce. Under the conditions of 34 mg l−1 H2O2, 0.500 g l−1 Fe–Ce, 36 W UV and pH 3.0, 100 mg l−1 X-3B could be decolorized at efficiency of more than 99% within 30 min. The maximum dissolved Fe during the reaction was 1 mg l−1. From the fact that the decolorization rate of the UV–Fe–Ce–H2O2 system was significantly higher than that of the UV–Fe3+–H2O2 system at Fe3+ = 1 mg l−1, it is clear that the Fe–Ce functioned mainly as an efficient heterogeneous catalyst. UV–vis, its second derivative spectra, and ion chromatography (IC) were employed to investigate the degradation pathway. Fast degradation after adsorption of X-3B is the dominant mechanism in the heterogeneous catalytic oxidation system. The first degradation step is the breaking down of azo and CN bonds, resulting in the formation of the aniline- and phenol-like compounds. Then, the breaking down of the triazine structure occurred together with the transformation of naphthalene rings to multi-substituted benzene, and the cutting off of sulphonic groups from the naphthalene rings. The last step includes further decomposition of the aniline structure and partial mineralization of X-3B. 相似文献
995.
Borgna A. Le Normand F. Garetto T. Apesteguia C. R. Moraweck B. 《Catalysis Letters》1992,13(3):175-188
The effect of an oxidative atmosphere (300 °C) is studied on fresh and sintered unchlorinated naphtha reforming catalysts containing 0.6–1% Pt. The TPR profiles show that only one species is formed using our experimental conditions, regardless of the mean crystallite size of the metal particles. The structural information supplied by EXAFS compared with cuboctahedral particle modeling, implies that such species is a surface platinum oxide, the structure of which is close to that of PtO2, but largely distorted. This is true whether the catalyst is sintered or not. 相似文献
996.
997.
A surfactant‐free method to produce responsive polymer microgels is introduced. As an example, poly(methacrylic acid) hydrogels with varying crosslinking density have been synthesized in bulk and then chopped using a high shear mechanical cutter to form microgel particles dispersed in water. The mechanical cutting technique enables the concentration and particle size distribution of the microgel suspensions to be easily controlled, therefore making the rheology of the suspensions tuneable. The particle size distribution of the dispersions, characterized using light scattering, was dependent on the speed and duration of mechanical cutting. The particle size distribution also depended on the degree of crosslinking of the hydrogel. The higher the crosslinking density, the lower the average mean diameter of the resulting microgel particles. The lower the crosslinking density of the hydrogel, the larger the difference between the maximum and minimum particle size. The time to complete swelling of the particles upon change in pH was measured to be up to 45 s, depending on the particle size. The rheology of the resulting suspensions as a function of pH was investigated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 104: 1912–1919, 2007 相似文献
998.
999.
1000.
国外过氧化氢在化学合成中应用研究进展 总被引:2,自引:0,他引:2
胡长诚 《化学推进剂与高分子材料》2003,1(6):1-4
介绍了近期国外过氧化氢在部分化学品合成中应用研究新进展 ,产品包括过碳酸钠、过碳酰胺、4Na2 SO4·2H2 O2 ·NaCl加合物、叔胺氧化物、水合肼、二羟基苯、季铵盐过氧化氢和甲乙酮肟。内容涉及产品质量 (纯度、安定性、溶解速率、外观等 )、产品收率、催化剂、工艺过程等方面改进。主要介绍专利技术。 相似文献