全文获取类型
收费全文 | 3452篇 |
免费 | 80篇 |
国内免费 | 21篇 |
专业分类
电工技术 | 83篇 |
综合类 | 118篇 |
化学工业 | 1257篇 |
金属工艺 | 398篇 |
机械仪表 | 59篇 |
建筑科学 | 116篇 |
矿业工程 | 239篇 |
能源动力 | 139篇 |
轻工业 | 536篇 |
水利工程 | 12篇 |
石油天然气 | 263篇 |
武器工业 | 1篇 |
无线电 | 31篇 |
一般工业技术 | 117篇 |
冶金工业 | 136篇 |
原子能技术 | 20篇 |
自动化技术 | 28篇 |
出版年
2024年 | 4篇 |
2023年 | 20篇 |
2022年 | 28篇 |
2021年 | 50篇 |
2020年 | 53篇 |
2019年 | 55篇 |
2018年 | 49篇 |
2017年 | 62篇 |
2016年 | 96篇 |
2015年 | 67篇 |
2014年 | 138篇 |
2013年 | 220篇 |
2012年 | 129篇 |
2011年 | 292篇 |
2010年 | 216篇 |
2009年 | 247篇 |
2008年 | 168篇 |
2007年 | 170篇 |
2006年 | 148篇 |
2005年 | 156篇 |
2004年 | 118篇 |
2003年 | 129篇 |
2002年 | 100篇 |
2001年 | 80篇 |
2000年 | 92篇 |
1999年 | 97篇 |
1998年 | 71篇 |
1997年 | 65篇 |
1996年 | 66篇 |
1995年 | 91篇 |
1994年 | 64篇 |
1993年 | 55篇 |
1992年 | 55篇 |
1991年 | 45篇 |
1990年 | 11篇 |
1989年 | 14篇 |
1988年 | 11篇 |
1987年 | 5篇 |
1986年 | 8篇 |
1985年 | 5篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有3553条查询结果,搜索用时 0 毫秒
71.
2—甲基蒽醌新工艺研制,省去了原间接操作法中的三道工序——酸析、过滤、干燥,转为直接操作法。其优点是:生产工序简单,能耗低,废水废酸量少,并能减少设备投资,降低产品成本,提高经济效益。 相似文献
72.
Single phase zirconolite (CaZrTi2O7) was synthesised by a novel method using acid corrosion to treat zirconolite–diopside mixture powders (2CaZrTi2O7–Mg2Si2O6). The mixture powders were prepared by solid state reaction method at 1200°C for 2 h. Single phase zirconolite powders were obtained by acid corrosion method with 5% hydrofluoric acid on the zirconolite–diopside Synroc mixture powders and washed with 10% acetic acid. 相似文献
73.
《Ceramics International》2015,41(4):5677-5687
Inorganic fiber shows good insulation performance in civil construction and industry insulation. In the present paper, tensile strength of slag fiber produced with molten blast furnace slag was investigated systematically with the Weibull distribution theory in comparison with glass and basalt fibers. It was found that the mean tensile strength reached 2578.60 MPa and the shape parameter m in Weibull distribution is 2.4494, which indicates a lower uniformity. Anti-corrosion performances were also studied by means of the mass and strength loss after acid and alkaline solution treatment. Furthermore, SEM and FTIR were used to analyze the structural characteristics of original and treated fibers. This work has proved that the H+ and OH− can both break the Si–O bond and then lead to the movement to high wavenumber for the bands of the symmetric stretching vibrations of [SiO4]-tetrahedra. The anti-corrosion results indicated that slag fibers could not be used in acid environment, while its anti-alkali performance is relatively excellent compared with glass and basalt fibers. 相似文献
74.
Seong-Soo Hong Gun-Dae Lee Jong-Won Park Dae-Won Park Kyung-Mok Cho Kwang-Jung Oh 《Korean Journal of Chemical Engineering》1997,14(6):491-497
In the present work, we have investigated the reduction of NO by propane over perovskite-type oxides prepared by malic acid
method. The catalysts were modified to enhance the activity by substitution of metal into A or B site of perovskite oxides.
In addition, the reaction conditions, such as temperature, O2 concentration, and space velocity have been varied to understand their effects on the catalytic performance. In the LaCoO3 type catalyst, the partial substitution of Ba and Sr into A site enhanced the catalytic activity in the reduction of NO.
For the La0.6Ba (Sr)o.4 Co1−x
FexO3 (x=0-1.0) catalyst, the partial substitution of Fe into B site enhanced the conversion of NO, but excess amount of Fe decreased
the conversion of NO. The surface area and catalytic activity of perovskite catalysts prepared by malic acid method showed
higher values than those of solid reaction method. The conversion of NO increased with increasing O2 concentration and contact time. The introduction of water into reactant feed decreased the catalytic activity but the deactivation
was shown to be reversible over La0.6Ba0.4Co1−x
,FexO3 catalyst. 相似文献
75.
76.
《分离科学与技术》2012,47(1):75-83
Abstract Empirical equations with correlation coefficients greater than 0.9 for the solvent extraction of GeCl4, GeBr4, acetylacetone, trifluoroacetylacetone, thenoyltrifluoroacetone, 1-nitropropane, bis-thenoyltrifluoroacetone zinc(II), and several dicarboxylic acids in various solvents are presented. 相似文献
77.
《国际聚合物材料杂志》2012,61(4):441-455
Abstract The cure kinetics of bisphenol-S epoxy resin (BPSER) and curing agent phthalic anhydride, with N,N-dimethyl phenzylamine as an accelerator, were studied by means of differential scanning calorimetry (DSC). Analysis of DSC data indicated that an autocatalytic behavior showed in the first stages of the cure. The autocatalytic behavior was well described by the model proposed by Kamal including two rate constants, k1 and k2, and two reaction orders, m and n. The overall reaction order, m + n, is in the range 2~3. The activation energies for k1 and k2 were 111.69 and 80.47 KJ/mol, respectively. Diffusion control was incorporated to describe the cure in the latter stages. The glass transition temperatures (TgS) of the BPSER/anhydride samples isothermally cured partially were determined by means of torsional braid analysis (TBA). and the results showed that the reaction rate increased with increasing Tg in terms of the rate constant, but decreased with increasing conversion. The Tg of completely cured BPSER/anhydride system is about 40 K higher than that of BPAER. The thermal degradation kinetics of this system was investigated by thermogravimetric analysis (TGA). It illustrated that the thermal degradation of the BPSER/phthalic anhydride has n-order reaction kinetics. 相似文献
78.
采用哈克转矩流变仪制得不同加工条件下的聚乳酸样品;采用差式扫描量热法(DSC)和熔体质量流动速率(MFR)对聚乳酸样品进行了结构表征和热性能分析。实验结果表明:随着加工温度、加工时间及转速等的增加,聚乳酸的黏度,玻璃化转变温度(Tg)等都有一定程度的减小,即加剧了聚乳酸的热降解。 相似文献
79.
以硼酸、乙醇胺、甲基丙烯酰氯为主要原料,合成了新型可聚合硼酸酯偶联剂BE-1。利用BE-1在硼酸镁晶须表面引发聚合形成有机涂层,并用改性后的硼酸镁晶须制备了硼酸镁晶须/聚丙烯(PP)复合材料。检测结果如下:由红外测试结果可以推断,合成产物即为可聚合硼酸酯偶联剂BE-1;在水解稳定性测试中BE-1稳定时间大于960 h,BE-1具有良好的溶解性及贮存性能;有机涂层形成的最佳反应温度为78℃,最佳反应时间为6 h;BE-1改性硼酸镁晶须/PP复合材料拉伸强度、弯曲强度、热变形温度分别比纯PP提高了30%、40%和104%,分别比未改性硼酸镁晶须/PP复合材料提高了11.05%、23.52%、15.29%。 相似文献
80.