全文获取类型
收费全文 | 1649篇 |
免费 | 119篇 |
国内免费 | 46篇 |
专业分类
电工技术 | 88篇 |
综合类 | 63篇 |
化学工业 | 257篇 |
金属工艺 | 187篇 |
机械仪表 | 95篇 |
建筑科学 | 137篇 |
矿业工程 | 62篇 |
能源动力 | 53篇 |
轻工业 | 79篇 |
水利工程 | 15篇 |
石油天然气 | 74篇 |
武器工业 | 11篇 |
无线电 | 147篇 |
一般工业技术 | 199篇 |
冶金工业 | 136篇 |
原子能技术 | 7篇 |
自动化技术 | 204篇 |
出版年
2024年 | 7篇 |
2023年 | 26篇 |
2022年 | 32篇 |
2021年 | 70篇 |
2020年 | 41篇 |
2019年 | 54篇 |
2018年 | 50篇 |
2017年 | 45篇 |
2016年 | 54篇 |
2015年 | 72篇 |
2014年 | 73篇 |
2013年 | 91篇 |
2012年 | 119篇 |
2011年 | 105篇 |
2010年 | 99篇 |
2009年 | 96篇 |
2008年 | 101篇 |
2007年 | 73篇 |
2006年 | 77篇 |
2005年 | 74篇 |
2004年 | 56篇 |
2003年 | 44篇 |
2002年 | 44篇 |
2001年 | 38篇 |
2000年 | 41篇 |
1999年 | 32篇 |
1998年 | 35篇 |
1997年 | 24篇 |
1996年 | 22篇 |
1995年 | 20篇 |
1994年 | 14篇 |
1993年 | 9篇 |
1992年 | 12篇 |
1991年 | 11篇 |
1990年 | 3篇 |
1989年 | 6篇 |
1988年 | 6篇 |
1987年 | 1篇 |
1986年 | 5篇 |
1985年 | 9篇 |
1984年 | 2篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有1814条查询结果,搜索用时 312 毫秒
31.
Liming Lee Kit Ian Kou Wentao Zhang Jinling Liang 《International journal of systems science》2016,47(10):2466-2474
In this paper, we consider finite-time control problems for linear multi-agent systems subject to exogenous constant disturbances and impulses. Some sufficient conditions are obtained to ensure the finite-time boundedness of the multi-agent systems, which could be then reduced to a feasibility problem involving linear matrix inequalities. Numerical examples are given to illustrate the results. 相似文献
32.
KOU Shengzhong XU Guangji DING Yutian 《武汉理工大学学报(材料科学英文版)》2005,20(4):50-54
High-energy ball milling has a great influence on the temperature characters of synthetic reaction in Al-TiO2-C system by changing the size,distribution state and wet ability of reactants.Reaction temperature characters(reaction ignition time,ignition temperature time.the maximum temperature and temperature rising rate)were changed by different milling time.The longer the milling time.the earlier the reaction.the quicker the temperature rise and the higher the maximum temperature.When the milling time exceeded 10 hours,the reactivity of reactants was so high that the synthetic reaction could take place at 850℃ directly without a long time pretreatment at 670℃.The microstructure of synthetic composites became uniform and the reinforced particles(TiC and α-Al2O3)became fine with milling time increasing. 相似文献
33.
分布式防空C~3I智能辅助决策模型 总被引:2,自引:0,他引:2
文章针对战场环境的动态性、不确定性和不可预测性,依据分布式防空C3I系统结构,对决策需求进行了分析,以战区级为背景,提出了智能辅助决策模型。 相似文献
34.
固化剂对环氧树脂/蒙脱土纳米复合材料中蒙脱土剥离行为的影响 总被引:2,自引:0,他引:2
采用阳离子交换的方法对蒙脱土进行了有机改性,使蒙脱土由亲水性变成亲油性,并使其层间距由原来的1.2nm扩大到2.2nm。分别使用甲基四氢苯酐和4,4’-二胺基二苯基甲烷为固化剂,制备两种环氧树脂/蒙脱土纳米复合材料,并用x一射线衍射仪和透射电镜(TEM)分析有机蒙脱土在环氧树脂中的剥离行为。研究表明,固化剂的选择对有机蒙脱土的剥离行为有很大的影响,用固化剂甲基四氢苯酐和促进剂苄基二甲胺后,有机蒙脱土容易被剥离而得到剥离型的纳米复合材料,而用4,4’-二胺基二苯基甲烷固化剂未能使有机蒙脱土剥离后形成插层型纳米复合材料。 相似文献
35.
36.
Iron was recovered from blast furnace dust and high-phosphorus oolitic hematite in the presence of Na2CO3 and CaCO3 additives. The functions of Na2CO3 and CaCO3 during the coreduction roasting process were investigated by XRD and SEM-EDS analyses. Results indicate that these additives not only hinder the reduction of fluorapatite, CaCO3 also decreases the P content of direct reduced iron (DRI) by increasing the reduction alkalinity. P remains as fluorapatite in the slag, which can be removed by grinding and magnetic separation under optimal conditions. The Na2CO3 promotes hematite reduction and improves the iron recovery (εFe) by replacing the FeO from fayalite, which results in quick growth and aggregation of metallic iron and improvement of εFe in DRI. A DRI with 91.88 mass% Fe, and 0.065 mass% P can be achieved at a recovery of 87.86 mass% under the optimal condition. 相似文献
37.
AbstractChina has experienced a surge in innovation output in which state-owned enterprises (SOE) play an essential role. Using panel data of Chinese listed firms, this paper examines the influence of state ownership on innovation output at the firm level. Controlling for size, we analyse the effects of central and local government control on the number of firms’ patent applications in different time periods. Doing so, standard assumptions on state ownership’s inhibiting character are confirmed. However, we then qualify these findings by running separate models for different regions and sectors finding that the impact of state-control on innovation performance depends on a number of conditions. More precisely, state control of firms has a negative impact on innovation output in particular in China’s Northeast region and in mid-tech sectors whereas under other circumstances it does either not matter or can even exert a positive influence. 相似文献
38.
Zhigang Zhao Kezhi Li Wei Li Qing Liu Gang Kou Yulei Zhang 《Ceramics International》2018,44(7):7481-7490
ZrC precursor was synthesized by a solution approach using ZrOCl2·8H2O, acetylacetonate, glycerol and boron-modified phenolic resin. A ZrC yield of ~ 40.56 wt% was obtained at 1500 °C in the C/Zr molar ratio of 1:1. C/C-ZrC-SiC composites were fabricated by a combined processes of chemical vapor infiltration (CVI) and precursor infiltration and pyrolysis (PIP) using the synthesized ZrC precursor. For comparison, C/C-SiC composites were prepared by CVI. Thermogravimetric analysis showed that C/C-ZrC-SiC composites exhibited better oxidation resistance than C/C-SiC composites. After oxyacetylene torch ablation, the mass ablation rate of C/C-ZrC-SiC composites was 9.23% lower than that of C/C-SiC composites. The porous ZrO2 skeleton in the ablation center was prone to be peeled off by the flame flow, resulting in the higher linear ablation rate of C/C-ZrC-SiC composites. The oxide layers of ZrO2 and SiO2 were formed on the transition and brim region of C/C-ZrC-SiC composites and acted as effective heat and oxygen barriers. For C/C-SiC composites, the C-SiC matrix was severely depleted in the ablation center and the formed SiO2 layer in the brim region could protect the matrix against further ablation. 相似文献
39.
G. Wang X. Tuo L. Kou W. Zhao X. Zhu 《Materialwissenschaft und Werkstofftechnik》2020,51(12):1686-1699
Salt spray corrosion test was carried out on 6061 aluminum alloy, and quasi-static tensile test at room temperature was carried out on the sample with universal testing machine. The effect of salt spray corrosion on the mechanical properties of 6061 aluminum alloy was studied by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and electrochemistry. The corrosion rate of 6061 aluminum alloy was quantitatively characterized by different corrosion parameters. It was found that local corrosion of 6061 aluminum alloy occurred in salt spray environment, mainly pitting corrosion and intergranular corrosion. With the increase of corrosion time, the polarization resistance of 6061 aluminum alloy decreases, and the corrosion rate significantly increases. The average corrosion rate and the maximum corrosion rate of 6061 aluminum alloy were characterized by corrosion weight loss and corrosion pit depth. And they can be transformed into each other. The mechanical properties of 6061 aluminum alloy were mainly affected by the depth of corrosion pit. With the increase of corrosion time, the tensile strength and fracture strain decreased, resulting in poor plasticity of the sample. At the same time, the change of elongation of 6061 aluminum alloy can be accurately predicted by the depth of corrosion pit. 相似文献
40.