全文获取类型
收费全文 | 88592篇 |
免费 | 14380篇 |
国内免费 | 50篇 |
专业分类
电工技术 | 1040篇 |
综合类 | 21篇 |
化学工业 | 26495篇 |
金属工艺 | 1202篇 |
机械仪表 | 1694篇 |
建筑科学 | 3147篇 |
矿业工程 | 108篇 |
能源动力 | 1926篇 |
轻工业 | 14868篇 |
水利工程 | 788篇 |
石油天然气 | 245篇 |
武器工业 | 6篇 |
无线电 | 8535篇 |
一般工业技术 | 19551篇 |
冶金工业 | 11949篇 |
原子能技术 | 202篇 |
自动化技术 | 11245篇 |
出版年
2024年 | 116篇 |
2023年 | 488篇 |
2022年 | 680篇 |
2021年 | 1556篇 |
2020年 | 2500篇 |
2019年 | 4304篇 |
2018年 | 4781篇 |
2017年 | 5009篇 |
2016年 | 5603篇 |
2015年 | 5153篇 |
2014年 | 5471篇 |
2013年 | 8669篇 |
2012年 | 5590篇 |
2011年 | 5128篇 |
2010年 | 4803篇 |
2009年 | 4491篇 |
2008年 | 4086篇 |
2007年 | 3727篇 |
2006年 | 2979篇 |
2005年 | 2512篇 |
2004年 | 2351篇 |
2003年 | 2274篇 |
2002年 | 2140篇 |
2001年 | 1764篇 |
2000年 | 1667篇 |
1999年 | 1126篇 |
1998年 | 3549篇 |
1997年 | 2362篇 |
1996年 | 1536篇 |
1995年 | 889篇 |
1994年 | 687篇 |
1993年 | 752篇 |
1992年 | 273篇 |
1991年 | 261篇 |
1990年 | 215篇 |
1989年 | 210篇 |
1988年 | 224篇 |
1987年 | 192篇 |
1986年 | 171篇 |
1985年 | 194篇 |
1984年 | 170篇 |
1983年 | 121篇 |
1982年 | 154篇 |
1981年 | 182篇 |
1980年 | 197篇 |
1979年 | 93篇 |
1978年 | 93篇 |
1977年 | 338篇 |
1976年 | 724篇 |
1973年 | 89篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
P. Podhájecký B. Klápště P. Novák J. Mrha R. Moshtev V. Manev A. Nassalevska 《Journal of power sources》1985,14(4):269-275
A dozen CuO samples prepared under various conditions and from different starting materials were evaluated as cathode materials for a primary Li/CuO cell. The “thin electrode” method was used for rapid evaluation of the samples. Both coulombic efficiency and discharge voltage depend considerably on the method of synthesis. No correlation was found between the specific surface area and the resistivity of the samples on the one hand and the cathode performance on the other. Best results were obtained from CuO prepared by the oxidation of Cu2O under controlled temperature and time of oxidation. 相似文献
93.
Wood has long traditions as a building material, and is often used in construction elements, and as interior and exterior surfaces in the Nordic countries. In most applications, there are reaction to fire requirements to products used as surfaces, e.g. in escape routes and larger public spaces. Most wood products will therefore have to be treated with fire retardant (FR) agents to fulfil the strict requirements to properties connected to heat release and flame spread. Unfortunately, FR agents usually also increase the smoke production, as they cause a more incomplete combustion of the wood. The wood product manufacturers seek to find the optimal amount of FR additives where both heat release and smoke production in the classifying test are within the requirements given in the building regulations. This paper describes models for prediction of the European reaction to fire classes of wood products. The models are based on multivariate statistical analysis, and use test results from the cone calorimeter test as input. The presented models are, with very good precision, able to predict which Euroclass and additional smoke class a wood based product would obtain if it were to be tested in the single burning item test. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
94.
We have assessed the antimicrobial, vapor-phase activity of the following natural essential oils (EOs) when used in paraffin-based “active coatings” for paper packaging materials intended to come into contact with foods: clove (Sygzium aromaticum), cinnamon (Cinnamomum zeylanicum), and oregano (Origanum vulgare) EOs, and cinnamaldehyde-enriched cinnamon EO. To our knowledge, this is the first time that such an approach has been presented for consideration by the scientific community. 相似文献
95.
A lectin-like protein was isolated from L. muta venom by gel filtration on BIO Gel P-100 followed by column Chromatography on DEAE-sephades A-50. The protein eluted at 0.4 M Nacl in 0.01 Tris pH 7.3 and exhibited agglutinin activity toward 0+ human erythrocytes. The protein is a dimer with Mr 28 kDa. Amino acid analysis revealed high content of tryptophan and acid recidues and low content of cysteine and methionine residues. No neutral carbohydrates and sialic acid were detected. Circular dichroic spectrum shows 78% of B structure and 1% of alpha structure. In vitro experiments with erythrocytes from rat, rabbit and dog revealed strong agglutination while red blood cells from mice, sheep and goat were not agglutinated. In vivo experiments using anesthetized rats, a sharp and prolonged fall in the blood pressure was observed at protein dose of 1.5 mg/kg. Double dose of protein caused the death of the animal. 相似文献
96.
97.
P Sánchez García 《Canadian Metallurgical Quarterly》1997,114(1):157-63; discussion 164-7
98.
The Vesilind settling velocity function forms the basis of flux theory used both in state point analysis (for design and capacity rating) and one-dimensional dynamic models (for dynamic process modelling). This paper proposes new methods to address known shortcomings of these methods, based on an extensive set of batch settling tests conducted at different scales. The experimental method to determine the Vesilind parameters from a series of bench scale settling tests is reviewed. It is confirmed that settling cylinders must be slowly stirred in order to represent settling performance of full scale plants for the whole range of solids concentrations. Two new methods to extract the Vesilind parameters from settling test series are proposed and tested against the traditional manual method. Finally, the same data set is used to propose an extension to one-dimensional (1-D) dynamic settler models to account for compression settling. Using the modified empirical function, the model is able to describe the batch settling interface independently of the number of layers. 相似文献
99.
A new analytical method has been developed for the determination of the reactive lysine content of soya bean protein. The method is based on the reaction of the free basic groups of the protein with 1-phenylazo-2 naphthol-6,8 disulphonic acid. With regard to the stoichiometry of the procedure, it has been proved, contrary to earlier reports, that the basic amino acids, histidine, arginine and lysine, each combine with one mole of the dye. After acylation with propionic anhydride lysine alone loses its dye reactivity. The usefulness of the proposed method has been demonstrated by the determination of the reactive lysine content of several untreated, heat-treated and acid-treated soya bean samples. The results show that heat damage of about 5% in reactive lysine content can be measured in 1·5 h with good reproducibility. 相似文献
100.