全文获取类型
收费全文 | 596篇 |
免费 | 57篇 |
国内免费 | 23篇 |
专业分类
电工技术 | 5篇 |
综合类 | 54篇 |
化学工业 | 147篇 |
金属工艺 | 19篇 |
机械仪表 | 22篇 |
建筑科学 | 9篇 |
矿业工程 | 5篇 |
能源动力 | 3篇 |
轻工业 | 351篇 |
水利工程 | 4篇 |
石油天然气 | 10篇 |
无线电 | 3篇 |
一般工业技术 | 21篇 |
冶金工业 | 16篇 |
原子能技术 | 2篇 |
自动化技术 | 5篇 |
出版年
2024年 | 5篇 |
2023年 | 7篇 |
2022年 | 16篇 |
2021年 | 15篇 |
2020年 | 18篇 |
2019年 | 24篇 |
2018年 | 24篇 |
2017年 | 21篇 |
2016年 | 17篇 |
2015年 | 29篇 |
2014年 | 40篇 |
2013年 | 47篇 |
2012年 | 50篇 |
2011年 | 49篇 |
2010年 | 23篇 |
2009年 | 30篇 |
2008年 | 23篇 |
2007年 | 43篇 |
2006年 | 32篇 |
2005年 | 32篇 |
2004年 | 26篇 |
2003年 | 15篇 |
2002年 | 20篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 3篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 10篇 |
1995年 | 2篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1981年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有676条查询结果,搜索用时 15 毫秒
1.
The extraction of nitrogenous material from Brewers' spent grain (BSG) by solvents (water, sodium chloride solution, aqueous alcohol, acidic and alkaline solutions) commonly used to extract cereal proteins, resulted in the relatively low (0·2 to 8·5%) recovery of the total nitrogen. The recovery of nitrogenous material by the use of aqueous alkaline solutions was increased from 3–4% to 41% when the BSG was subjected to cellulase incubation prior to extraction. Approximately 75% of the nitrogen was solubilized with trifluoracetic acid. Detergent solutions (acid, neutral) solubilized more than 80% of the total nitrogen of the BSG. The low solubility of the nitrogenous constituents by conventional protein solvents could be the result of association between cellulosic material and protein. 相似文献
2.
Degumming of hemp fiber by high temperature alkali cooking was investigated, and the effect of temperature and dosage of alkali on the constituents, structure, and thermal degradation of hemp fiber was also discussed in this work. The morphology, structure, and thermal degradation of hemp fiber after high temperature cooking were investigated through SEM, FTIR, WAXD, and TG analysis. The results indicated that the high temperature cooking process was effective for removing hemicelluloses and lignin and could also improve the thermal stability of cellulose. Crystallinity index of the treated hemp fiber was increased, which was related to the cooking temperature and NaOH dosage. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
3.
水泥的品质和混凝土质量的关系(上) 总被引:6,自引:0,他引:6
在传统上,混凝土是按强度进行设计的,对混凝土的质量的最终标准主要是强度,因此混凝土生产者对水泥品质的要求也是强调强度;强度越高的水泥被认为质量也越高,如此的发展,造成近年来混凝土结构出现裂缝尤其是早期开裂的现象日益普遍。其原因很复杂,单从水泥来说,比表面积、矿物组成中C3A、C3S、碱含量的增加,热水泥的出厂,都增加了开裂的敏感性,降低了流变性能,是原材料中影响混凝土质量主要原因。应当把抗裂性作为水泥品质的重要要求,并限制出厂水泥的温度。 相似文献
4.
B. S. Goodrich E. R. Hesterman K. S. Shaw R. Mykytowycz 《Journal of chemical ecology》1981,7(5):817-827
A study has been made of the volatile constituents in the vapors collected from fecal pellets of wild rabbits,Oryctolagus cuniculus. Measurements of changes in the heart rates of adult male rabbits exposed to the effluent of a gas chromatographic capillary column were used to indicate the presence of compounds which may be of behavioral significance. Combined with the use of high-resolution columns in gas chromatography and gas chromatography-mass spectrometry, this approach has implicated several classes of compounds, including volatile fatty acids and phenols, which in certain absolute or relative concentrations may be involved in the formation of signals of territorial importance. 相似文献
5.
6.
Ionic liquids as electrolytes 总被引:5,自引:0,他引:5
Salts having a low melting point are liquid at room temperature, or even below, and form a new class of liquids usually called room temperature ionic liquids (RTIL). Information about RTILs can be found in the literature with such key words as: room temperature molten salt, low-temperature molten salt, ambient-temperature molten salt, liquid organic salt or simply ionic liquid. Their physicochemical properties are the same as high temperature ionic liquids, but the practical aspects of their maintenance or handling are different enough to merit a distinction. The class of ionic liquids, based on tetraalkylammonium cation and chloroaluminate anion, has been extensively studied since late 1970s of the XX century, following the works of Osteryoung. Systematic research on the application of chloroaluminate ionic liquids as solvents was performed in 1980s. However, ionic liquids based on aluminium halides are moisture sensitive. During the last decade an increasing number of new ionic liquids have been prepared and used as solvents. The general aim of this paper was to review the physical and chemical properties of RTILs from the point of view of their possible application as electrolytes in electrochemical processes and devices. The following points are discussed: melting and freezing, conductivity, viscosity, temperature dependence of conductivity, transport and transference numbers, electrochemical stability, possible application in aluminium electroplating, lithium batteries and in electrochemical capacitors. 相似文献
7.
8.
9.
研究了香薷、鹤虱等5种药用植物挥发油对仓虫的生物活性作用。结果表明,香薷挥发油的作用最为明显,它(剂量02μL/g)及其粗分离1#~5#样品(剂量005μL/g)均有效地抑制了试虫卵、幼虫及成虫的生长发育,从而减少了试虫F1代种群的发生,其中粗分离1#样品作用尤为突出。香薷挥发油1#~5#样品的主要化学成分为4,5,6,7,8,8a-六氢-8a-甲基-2[1H]-奥酮(5264%)、百里香酚(305%)和一未定成分(2192%)。 相似文献
10.