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排序方式: 共有3121条查询结果,搜索用时 46 毫秒
71.
Jeonghyeon ParkKwang Bok Yi 《International Journal of Hydrogen Energy》2012,37(1):95-102
A novel and economical method for preparing CaO-based high-temperature CO2 absorbents for sorption-enhanced hydrogen production is introduced. CaO-MgO absorbents prepared by the co-precipitation method show excellent cyclic stability but poor absorption capacity (∼8-14 g CO2/100 g absorbent). An additional hydration process provided spacious CO2 pathways resulting in a significant increase of the absorption capacity (∼17.4-47.8 g CO2/100 g absorbent) with excellent cyclic stability. As the MgO content increased, the absorption ratio of the absorbent and the degree of CaO conversion also increased. In addition, XRD analysis revealed that the hydration process followed by calcination at 900 °C led to the formation of a partial solid solution in the CaO-MgO absorbent containing 25 wt% MgO. 相似文献
72.
Zhongqiu Li Xiaobei Cheng Wenming Wei Liang Qiu Hui Wu 《International Journal of Hydrogen Energy》2017,42(38):24055-24066
The main purpose of this study is to investigate the effects of hydrogen addition on the laminar flame speeds of methane, ethane and propane. In this work, a flat flame method was used to measure the laminar flame speed in a counter-flow configuration combined with particle image velocimetry (PIV) system. The results indicate that with the increase of hydrogen amount, the laminar flame speeds of methane, ethane and propane increase linearly approximately. In addition, as hydrogen is increased, the flame speed of methane has the maximum increasing amplitude among them, which indicates that methane is more sensitive to hydrogen addition in flame speed than the other two fuels.Simulation analysis finds that the reaction R1: H + O2 ? OH + O can promote the flame speeds of these three kinds of gaseous fuel obviously, and with the increase of hydrogen amount, the promoting effect is more obviously. Therefore, the main reason why hydrogen addition could increase flame speed is that the increase of H radical prompts reaction R1 to proceed in the forward direction. Comparing the flames of methane, ethane and propane mixed with hydrogen, it was found that the promotion of reaction R1 to the methane/hydrogen mixtures flame speed is strongest, and its free radicals concentration in flame increase more obviously. Therefore, hydrogen addition has a greater effect on the flame speed of methane than on that of ethane and propane. 相似文献
73.
Azam Movasati Seyed Mehdi Alavi Golshan Mazloom 《International Journal of Hydrogen Energy》2017,42(26):16436-16448
The catalytic performance of Ni supported on Ce-promoted ZnAl2O4 was evaluated in methane dry reforming. The effect of different nominal loadings of cerium (3, 5 and 7 wt%) in the activity, product yield and stability was studied. Ce presented a promote effect in catalytic activity, product yield and especially in stability. However the catalytic performance was considerably influenced by the amount of cerium. SEM images presented smaller particles and TPR profiles revealed stronger active phase/support interaction by Ce addition which led to increasing methane conversion and decreasing coke deposition. Although high amount of Ce was not in favor of its promoting effect due to aggregation of CeO2 on the catalyst surface. Among the catalysts investigated, the optimal catalytic activity and stability was achieved over the sample with 5 wt% of cerium. 相似文献
74.
75.
以3,3,3-三氟丙烯和溴为原料,经加成反应合成了中间产物1,2-二溴-3,3,3-三氟丙烷,随后在氢氧化钠水溶液中进行消除反应制备了目标产物2-溴-3,3,3-三氟丙烯,通过试验得到了较佳的反应条件。 相似文献
76.
《国际聚合物材料杂志》2012,61(3-4):435-449
Abstract Based on a kinetic model involving competing parallel reactions for free-radical addition to the double bond of a molecule with the formation of 1:1 adduct and participation of three radical types in the chain propagation, versions of the rate equation with 1 - 3 measurable parameters are derived. These versions make it possible to describe the nonmonotonic (with maximum) dependence of the formation rate of an addition product on concentration of the unsaturated compound. The unbranched chain process occurs in binary liquid systems comprising saturated and unsaturated components at comparable concentrations. Application of the competition kinetics of free-radical addition to oxidation of some hydrocarbons is discussed when the reaction that competes with chain propagation reactions involving the alkylperoxy radical RO2 gives the cyclic alkylhydrotetraoxy radical [R(?H)O4H] as a less reactive radical inhibiting the chain process of formation of the main products of oxidation. 相似文献
77.
《国际聚合物材料杂志》2012,61(3-4):181-192
Abstract The essence of chemical modification processes of fiber-forming polymers based on recombination addition reactions involves preliminary sorption of low-molecular components by the fiber being in a high elasticity state with the subsequent transfer of interacting substances into a free radical state as a result of chemical or radiation initiation. Recombination of activated parts then leads to the fixation of a low-molecular component in a polymer matrix. Various versions of these reactions based on modifications of fibrillar proteins (fibroin and keratin). polyamides. cellulose and its esters, polyvinyl alcohol with ionogenic (cationic and anionic) and non-ionogenic (disperse) dyes of different classes have been considered. 相似文献
78.
介绍了湿型砂各组分的作用,论述了型砂性能与其组分的关系,认为控制好有效膨润土量和有效添加剂量是控制型砂质量的关键,结合生产实例说明了型砂质量的控制要点;指出提高型砂质量控制水平、生产优质铸件和实现铸造生产循环用砂是铸造生产节能减排的根本方法之一。 相似文献
79.
以Ti、Al、TiO2为起始原料,以Er2O3为掺杂剂,原位热压合成了Er掺杂Al2O3/TiAl复合材料。通过XRD、SEM分析及力学性能测试,研究了不同Er2O3引入量对合成Al2O3/TiAl复合材料微观结构和力学性能的影响。结果表明:复合材料主要由TiAl、Ti3 Al、Al2 O3相和少量Al10 Er6 O24相组成,含Er相主要分布在基体相晶界处;掺杂0.01 mol Er2 O3制得的复合材料,经1250℃保温2 h真空热压烧结后表观断裂韧性达到最大值(10.41 MPa.m1/2),经1300℃保温2 h真空热压烧结后弯曲强度达到最大值(456.06 MPa);当Er2O3掺杂量增加到0.02 mol时,复合材料的弯曲强度和表观断裂韧性均呈减小趋势。微观结构分析表明,掺杂0.01 mol Er2O3的复合材料断口毛糙,颗粒尺寸变小,增强相分布较均匀,表明适量的Er2O3掺杂可细化复合材料晶粒尺寸,提高增强颗粒分布均匀度,起到增强增韧的效果。 相似文献
80.