全文获取类型
收费全文 | 10191篇 |
免费 | 334篇 |
国内免费 | 106篇 |
专业分类
电工技术 | 51篇 |
综合类 | 376篇 |
化学工业 | 2931篇 |
金属工艺 | 235篇 |
机械仪表 | 116篇 |
建筑科学 | 385篇 |
矿业工程 | 81篇 |
能源动力 | 655篇 |
轻工业 | 1849篇 |
水利工程 | 51篇 |
石油天然气 | 342篇 |
武器工业 | 5篇 |
无线电 | 1757篇 |
一般工业技术 | 1325篇 |
冶金工业 | 177篇 |
原子能技术 | 58篇 |
自动化技术 | 237篇 |
出版年
2024年 | 14篇 |
2023年 | 66篇 |
2022年 | 131篇 |
2021年 | 280篇 |
2020年 | 206篇 |
2019年 | 151篇 |
2018年 | 152篇 |
2017年 | 335篇 |
2016年 | 359篇 |
2015年 | 343篇 |
2014年 | 738篇 |
2013年 | 662篇 |
2012年 | 738篇 |
2011年 | 829篇 |
2010年 | 571篇 |
2009年 | 703篇 |
2008年 | 511篇 |
2007年 | 594篇 |
2006年 | 496篇 |
2005年 | 396篇 |
2004年 | 347篇 |
2003年 | 309篇 |
2002年 | 283篇 |
2001年 | 211篇 |
2000年 | 205篇 |
1999年 | 189篇 |
1998年 | 144篇 |
1997年 | 145篇 |
1996年 | 116篇 |
1995年 | 89篇 |
1994年 | 85篇 |
1993年 | 48篇 |
1992年 | 49篇 |
1991年 | 34篇 |
1990年 | 22篇 |
1989年 | 18篇 |
1988年 | 18篇 |
1987年 | 17篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1979年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
两种具有电双稳态的全有机络合物 总被引:9,自引:0,他引:9
首次发现两种在室温下即具有电双稳态的全有机(有机-有机)络合物,分别称为MCA+TCNQ和BBDN+TCNQ。它们可在真空中制备成薄膜,在数伏电压的作用下,从高电阻至低电阻的跃迁时间小于100ns,因此可作为一次写入的存储器材料。根据我国目前最小刻线宽度的水平,可望在1.6cm2的SiO2平面上做出64Mb的存储器。 相似文献
62.
Weihang Sun Dongfang Liu Minghui Zhang 《Frontiers of Chemical Science and Engineering》2021,15(6):1427
The dye industry produces a large amount of hazardous wastewater every day worldwide, which brings potential threaten to the global environment. As an excellent method for removal of water chroma and chemical oxygen demand, electrocatalytic methods are currently widely used in the treatment of dye wastewater. The selection and preparation of electrode materials and electrocatalysts play an important role on the electrocatalytic treatment. The aim of this paper is to introduce the most excellent high-efficiency electrode materials and electrocatalysts in the field of dye wastewater treatment. Many electrode materials such as metal electrode materials, boron-doped diamond anode materials and three-dimensional electrode are introduced in detail. Besides, the mechanism of electrocatalytic oxidation is summarized. The composite treatment of active electrode and electrocatalyst are extensively examined. Finally, the progress of photo-assisted electrocatalytic methods of dye wastewater and the catalysts are described. 相似文献
63.
Hongbing Song Lei Liu Bingxiao Feng Haozhong Wang Meng Xiao Hengjun Gai Yubao Tang Xiaofei Qu Tingting Huang 《中国化学工程学报》2021,40(12):293-303
In this work, modified g-C3N4 was fabricated successfully by calcination of ionic liquid (IL) and urea. The addition of IL changed the polymerization mode of urea, induced the self-assembly of urea molecules, modified the morphological structure of the tightly packed g-C3N4, and extended the electron conjugation system. When using 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) as a modifier, the heteroatom Cl could be inserted into the g-C3N4 to optimize the electronic structure. The results of characterizations indicate that the unique structure of modified g-C3N4 has an expanded electron delocalization range, introduces an interlayer charge transmission channel, promotes the charge transmission, reduces the band gap, enhances the absorption of visible light, and inhibits electron-hole recombination. Modified g-C3N4 showed excellent photocatalytic performance for the degradation of rhodamine B and tetracycline. Furthermore, the effect of different anions in 1-butyl-3-methylimidazolium salts ([Bmim]Cl, [Bmim]Br, [Bmim][BF4], and [Bmim][PF6]) on the structure and function of g-C3N4 are discussed. 相似文献
64.
为了提高天然染料对棉纤维的染色固色性能,以聚马来酸(PMA)和柠檬酸(CA)为交联剂应用于天然染料指甲醌对棉织物的交联染色。采用FTIR、SEM和XRD分析了染色前后棉织物的表面形态及结构,探讨了酯交联对棉织物性能的影响以及多元羧酸复配交联染色机理。结果表明,染色前后棉织物表面差别不大,各纤维间不粘连;直接染色后的棉纤维表面变化不明显,仅有少量染料附着,而交联染色后的棉纤维表面负载较多的染料导致其粗糙度增加,酯化反应主要发生在纤维的非晶态区。与直接染色棉织物相比,交联染色棉织物的染色深度(K/S)和上染率分别提高了88%和38%;染品的绿光、黄光增加,颜色饱和度提高;摩擦色牢度提高了1~2级;耐洗色牢度提高了1~2级;交联染色后棉织物的折皱回复角(WRA)提高了约60%,UPF值达到了50+,具有优异的抗紫外性能。 相似文献
65.
Liyan Qiu Ajit Dattatray Phule Weipeng Zhong Shibao Wen Zhenxiu Zhang 《大分子材料与工程》2021,306(12):2100481
Development of industrialization has brought convenience to people's lives; however, it has also brought serious harm to the environment, where, water pollution is the most obvious. Here, a polybutylene adipate terephthalate (PBAT) open-cell foam doped with iron-pillared bentonite (IPB) is prepared by using sugar as a pore-forming agent and solution phase separation, and then combined with a solution dipping method to coat the foam surface with a polyacrylamide/SiO2, which makes the PBAT foam superhydrophilic. The static adsorption effect of superhydrophilic IPB-doped PBAT open-cell foam on methylene blue (MB) and Cu2+ is studied. The adsorption isotherm fitting shows that the adsorption conforms to the Langmuir model and it has biased toward monolayer adsorption. The adsorption kinetics fitting confirms that the adsorption process is in line with the pseudo-second-order adsorption model, which is dominated by chemical adsorption. The modified PBAT open-cell foam has an adsorption effect on Cu2+; however, it has weak cyclic adsorption capacity. It shows a good cyclic adsorption ability for the cationic dye MB and it has >95% photodegradation efficiency of the MB after five time's cyclic adsorption. The superhydrophilicity makes the foam to have better applications in oil–water separation. 相似文献
66.
After comparing the influences of each rare earth(Ⅲ),11 species of metal(Ⅱ)and 8 species of acidictriphenylmethane dye on the formation of coloured coordination compound in the system of Metal(Ⅱ)-RE(Ⅲ)-Dye,it was proven that the co-colouration effect can be caused only by the xanthene dyes(XD)con-taining substituting hydroxy.group on the ortho-position of etheric oxygen group.Besides,the radius of met-al(Ⅱ)must not be smaller than a definite limit;otherwise,no co-colouration appears.Furthermore,the acid-ity of medium is another important factor to affect co-colouration,Bromopyrogallol red causesco-colouration of Pb(Ⅱ)-RE(Ⅲ)only,owing to its higher chromophoric acidity;while alizarin violet causesco-colouration of M(Ⅱ)-RE(Ⅲ)(M=Pb,Ca,Sr and Ba),due to its lower chromophoric acidity.The condi-tions causing co-colouration,the regularities of co-colouration and the influences of co-colouration inphotometric determination of metals were discussed. 相似文献
67.
Electrochemical injection of organic corrosion inhibitors into carbonated cementitious materials: Part 1. Effects on pore solution chemistry 总被引:4,自引:0,他引:4
This series of investigations was intended to clarify phenomena associated with electrochemical injection of the organic base corrosion inhibitors, ethanolamine and guanidine, into carbonated concrete. In Part 1, experiments were conducted with laminated specimens of carbonated cement paste, that were specially designed to facilitate analysis with adequate spatial resolution to assess changes in their pore solution phase chemistry after they had been subjected to constant current electrolysis between embedded cathodes and external anodes. The anolyte solutions provided sources of ethanolamine or guanidine in contact with the exterior specimen surfaces. Effects of variations in the applied current density and duration of electrolysis on the concentration profiles of the two inhibitors and the other main constituents of the pore solution phase were determined. The results have been used to underpin the development of a mathematical model, which is described in Part 2. 相似文献
68.
Mingru Zhang Jianqing Qian Haicheng Gu 《Journal of Materials Engineering and Performance》2007,16(5):635-639
Metallographic structures of carbide-free bainite steel wheel rim are mainly composed of supersaturated lath ferrite and retained
austenite film among bainitic ferrite laths. It is suspected that supersaturated ferrite and retained austenite are likely
to decompose under the influence of temperature change and mechanical stress. Stability of wheel rim structure is studied
by means of x-ray diffraction, dye microscopy, and micro-hardness test. When the samples are tempered in the range of 150-350 °C,
the retained austenite films are at the state of relative stability. Fifty percent of retained austenite is decomposed when
the sample is tempered at 400 °C. Microhardness increases when the sample is tempered at 150 °C. The decrease in hardness
is mild when the samples are tempered from 200 to 500 °C. The mechanical stability of retained austenite film is studied with
tensile sample under the effect of tensile stress. The retained austenite appears to be stable in low and middle degree of
deformation, and decomposition occurs at great amount of deformation. Diffraction peak of carbide is not found in all above
experiments. The steel enriched silicon prevents the carbide precipitation during the transformation. It indicates the carbide-free
bainite wheel steels have an excellent thermal and mechanical stability. 相似文献
69.
不同分散染料微胶囊的制备及应用 总被引:7,自引:2,他引:7
采用原位聚合法进行双层造壁,对不同结构的分散染料进行胶囊化。将分散染料高速均化后,在pH=4~6时加入TMM,65℃保温1.5小时,再滴加一定量PEHMM,在75℃时保温2.5小时进行双层造壁、C.I.分散橙30染料胶囊的粒径平均值为13.53μm,中值8.732μm;C.I.分散蓝56微胶囊粒径平均值为36.3μm,中值24.87μm。胶囊染色结果显示:这两只染料性能优于传统染料,染色后其废液的吸光度分别为0.021和0.003,比传统染色废水的1.286和0.786低很多。 相似文献
70.
以水杨醛类Schiff碱为配体,与Co(NO_3)_2、Cu(NO_3)_2反应合成6种Salen(M)型配合物Ⅰ~Ⅵ。以1-己硫醇、二丁基硫醚和2-甲基噻吩为模型化合物配制模拟油体系,考察了配合物Ⅰ~Ⅵ的催化氧化脱硫性能,并分析了配合物结构与氧化脱硫性能的关系。结果表明,6种配合物在75 min时的总脱硫效果为Ⅵ>Ⅴ>Ⅳ>Ⅰ>Ⅲ>Ⅱ,Ⅵ的总脱硫率为31.9%。对1-己硫醇及二丁基硫醚脱除效果最佳的是Ⅴ,脱除率分别为74.2%和65.1%;对2-甲基噻吩脱除效果最好的是Ⅰ,脱除率为26.8%。构效关系研究表明,中心金属离子与O_2的配位能力越强,配体的共轭体系越大、电子云密度越高,配合物的脱硫性能越好;通过IR和离子色谱对单一硫化物模拟油体系氧化前后的产物进行分析发现,硫化物氧化后皆生成相应的砜类或亚砜类,且1-己硫醇和二丁基硫醚被进一步氧化生成SO_3~(2–)或SO_4~(2–)。 相似文献