全文获取类型
收费全文 | 11397篇 |
免费 | 1600篇 |
国内免费 | 1008篇 |
专业分类
电工技术 | 279篇 |
技术理论 | 1篇 |
综合类 | 843篇 |
化学工业 | 1046篇 |
金属工艺 | 496篇 |
机械仪表 | 494篇 |
建筑科学 | 1167篇 |
矿业工程 | 754篇 |
能源动力 | 258篇 |
轻工业 | 820篇 |
水利工程 | 861篇 |
石油天然气 | 2569篇 |
武器工业 | 133篇 |
无线电 | 1040篇 |
一般工业技术 | 990篇 |
冶金工业 | 299篇 |
原子能技术 | 206篇 |
自动化技术 | 1749篇 |
出版年
2024年 | 65篇 |
2023年 | 266篇 |
2022年 | 512篇 |
2021年 | 582篇 |
2020年 | 548篇 |
2019年 | 521篇 |
2018年 | 429篇 |
2017年 | 470篇 |
2016年 | 591篇 |
2015年 | 546篇 |
2014年 | 777篇 |
2013年 | 827篇 |
2012年 | 829篇 |
2011年 | 809篇 |
2010年 | 566篇 |
2009年 | 510篇 |
2008年 | 537篇 |
2007年 | 600篇 |
2006年 | 595篇 |
2005年 | 499篇 |
2004年 | 479篇 |
2003年 | 394篇 |
2002年 | 303篇 |
2001年 | 296篇 |
2000年 | 267篇 |
1999年 | 206篇 |
1998年 | 157篇 |
1997年 | 145篇 |
1996年 | 124篇 |
1995年 | 108篇 |
1994年 | 92篇 |
1993年 | 67篇 |
1992年 | 65篇 |
1991年 | 47篇 |
1990年 | 42篇 |
1989年 | 32篇 |
1988年 | 16篇 |
1987年 | 9篇 |
1986年 | 11篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1977年 | 4篇 |
1964年 | 3篇 |
1959年 | 2篇 |
1957年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
对液压胀形轧辊(即国外的VC轧辊)辊套热装后的弹性变形进行了有限元分析,给出了确定油槽最小深度的计算公式。本文的有限元计算结果与实验结果吻合,某些结论可为液压胀形轧辊的结构设计提供理论依据。 相似文献
2.
3.
A rapid and easy analysis method for polymers is presented. The method involves sample preparation by SFE, separation of the extracted compounds by SFC and simultaneous quantitative detection by FID, as well as identification of unknowns by MS. The applications illustrate how structural research work and routine polymer analysis can be done with this time saving method. 相似文献
4.
Fourteen commercial polyadipates and a polysebacate were analysed for their components of a molecular mass below 1000 Da, primarily with the aim of generating the background data for measuring the migration of this type of polymeric additives from plasticized PVC (e.g. cling films and gaskets of lids) into foods or food simulants. Since the composition of the material <1000 Da varies between the polyadipates, the main components must be identified to enable a correct quantification. Polyadipates differ in the diol used as linker, their termination (acid or alcohol) and in the end‐capping (free alcohols, acetylation, acylation with fatty acids, esterification with octanol/decanol). Gas chromatography (GC) provides good separation, but the material remaining in the column up to high temperatures decomposes and forms a hump in the rear part of the chromatogram. Examples of mass spectra are shown, the most indicative fragments pointed out and spectra of 159 components listed. The polyadipates and the sebacate are characterized by their structure, the main components <1000 Da and the fraction of material <1000 Da. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
5.
6.
7.
An inductively coupled (ic) radio-frequency (rf) stabilized argon plasma was generated in a quartz tube using a 7 MHzrf generator. The electrical and thermal powers were measured and the efficiency of energy conversion was computed. The results
indicate that for a constant power input, there is an optimum argon flow rate for which maximum energy conversion efficiency
occurs. 相似文献
8.
Migration kinetics of straight-chain oligomers and antioxidants from several polyolefins at different temperatures into various solvents have been studied by radioactive tracer techniques. Anhydrous ethanol appears to be a well suited food-oil or liquid-fat simulant for extracting different types of migrants from polyolefins. Pure and mixed triglycerides are also good oil or fat simulants, but the triglycerides offer no simpler analytical procedures than the use of oil or fat themselves. n-Octanol may also be considered as a reasonable oil or fat simulant; however, its action depends somewhat on the choice of migrants. The accelerating action of n-heptane over that of oil or simulants is quantitatively demonstrated. The accelerating effects are greater for migration systems with lower diffusion coefficients. The diffusion coefficients for migration into n-heptane are about 20 times greater than the diffusion coefficients into ethanol or oil for otherwise identical migration systems yielding diffusion coefficients of about 10?7 cm2s?1 into oil or ethanol. For systems yielding diffusion coefficients into oil or ethanol of about 10?12 cm2s?1, the corresponding diffusion coefficients into n-heptane are about 1000 times greater. The molecular weight distributions (MWDs) of the n-heptane and ethanol extracts of polyolefins have been analysed. n-Heptane can not only accelerate the migration of the individual migrant but also remove oligomer species that are slightly soluble or present at low levels in the oil or simulant extracts. 相似文献
9.
Controlled calcination of ion-exchanged Wyoming Bentonite in the presence and absence of ammonia leads to layer charge reductions. Detailed chemical analyses of both unexchangeable and exchangeable species lead to the conclusion that in no case is there migration of the original interlamellar cations into the octahedral region of the layers although, in terms of ionic radius alone, Mg2+, Ni2+ and, possibly Co2+, might be expected to do so. The production of unexchangeable Mg, Ni or Co, is identified as resulting from high temperature hydrolysis leading to hydroxide or oxide formation. 相似文献
10.
邵静涵 《数码设计:surface》2014,(11):90-92
文章对产品设计艺术形式的深度创新进行了分析与探索。选取家电、家居产品、五金产品、交通产品、数码电子产品中典型的中外设计案例,结合比较学的方法对优秀产品的深层创新与其它产品中的浅层创新做了比较分析。论述了产品设计中艺术形式创新应包含的本质内容。艺术形式深度创新的本质包括:为解决平凡生活中的某个问题而设计的形式;作为新技术的先导而设计的形式。研究的结论对减少资源浪费,提高人的生活质量,正确引导未来的设计走向具有重要意义。 相似文献