全文获取类型
收费全文 | 4990篇 |
免费 | 756篇 |
国内免费 | 206篇 |
专业分类
电工技术 | 63篇 |
综合类 | 313篇 |
化学工业 | 1697篇 |
金属工艺 | 29篇 |
机械仪表 | 35篇 |
建筑科学 | 155篇 |
矿业工程 | 1076篇 |
能源动力 | 688篇 |
轻工业 | 225篇 |
水利工程 | 18篇 |
石油天然气 | 1133篇 |
武器工业 | 6篇 |
无线电 | 73篇 |
一般工业技术 | 204篇 |
冶金工业 | 86篇 |
原子能技术 | 41篇 |
自动化技术 | 110篇 |
出版年
2024年 | 10篇 |
2023年 | 89篇 |
2022年 | 163篇 |
2021年 | 180篇 |
2020年 | 192篇 |
2019年 | 210篇 |
2018年 | 227篇 |
2017年 | 208篇 |
2016年 | 197篇 |
2015年 | 210篇 |
2014年 | 359篇 |
2013年 | 263篇 |
2012年 | 365篇 |
2011年 | 367篇 |
2010年 | 271篇 |
2009年 | 270篇 |
2008年 | 218篇 |
2007年 | 264篇 |
2006年 | 248篇 |
2005年 | 232篇 |
2004年 | 170篇 |
2003年 | 166篇 |
2002年 | 140篇 |
2001年 | 137篇 |
2000年 | 109篇 |
1999年 | 104篇 |
1998年 | 98篇 |
1997年 | 83篇 |
1996年 | 99篇 |
1995年 | 71篇 |
1994年 | 67篇 |
1993年 | 37篇 |
1992年 | 24篇 |
1991年 | 27篇 |
1990年 | 16篇 |
1989年 | 13篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1984年 | 10篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1951年 | 5篇 |
排序方式: 共有5952条查询结果,搜索用时 0 毫秒
1.
Prediction of methane adsorption content in continental coal-bearing shale reservoir using SLD model
Shale gas, as an important unconventional resource, has drawn global attention. It is mainly composed of adsorption gas and free gas. Adsorption gas content could play an important guiding role on both the selection of favorable perspective area and the exploration and exploitation of shale gas resources. In order to accurately measure adsorption gas content, a new approach was established to predict the adsorption isotherm of methane on shale. Based on the simplified local-density (SLD) method, both the adsorption isotherms of illite, illite/smectite mixed-layer, cholorite and type III kerogen and the total shale rock could be well fitted. The fitting results show good coincidences with the true experimental test data, which proves the method is reasonable and dependable and the prediction results are effective and credible. In addition, the good simulation results show that the SLD parameters can reflect the pore structure characteristics and corresponding adsorption characteristics of the shale samples, which can be used for the quantitative characterization of shale pore system. 相似文献
2.
Hydrate formation rate plays an important role in making hydrates for the storage and transport of natural gas. Micellar surfactant solutions were found to increase gas hydrate formation rate and storage capacity. With the presence of surfactant, hydrate could form quickly in a quiescent system and the energy costs of hydrate formation reduced. Surfactants (an anionic surfactant, a non‐ionic surfactant and their mixtures) and liquid hydrocarbons (cyclopentane and methylcyclohexane) were used to improve hydrate formation. The experiments of hydrate formation were carried out in the pressure range 3.69–6.82 MPa and the temperature range 274.05–277.55 K. The experimental pressures were kept constant during hydrate formation in each experimental run. The effect of anionic surfactant (sodium dodecyl sulphate (SDS)) on natural gas storage in hydrates is more pronounced compared to a non‐ionic surfactant (dodecyl polysaccharide glycoside (DPG)). The induction time of hydrate formation was reduced with the presence of cyclopentane (CP). Cyclopentane and methylcyclohexane (MCH) could increase hydrate formation rate, but reduced hydrate storage capacity The higher methylcyclohexane concentration, the lower the hydrate storage capacity. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
3.
文中对影响煤矿许用毫秒延期电雷管沼气安全性与延期时间精度的因素进行了研究。应用正交设计研制了新的延期药配方,确定了合理的雷管结构及装配工艺参数,产品性能达到GB8031《工业电雷管》的规定。 相似文献
4.
5.
P. S. Lawson 《Biomass & bioenergy》1992,2(1-6):319-330
In recent years it has been recognised by an increasing number of nations that there is considerable energy potential within MSW. As a result many countries have established R,D& D programmes to examine methods of exploiting this potential. The IEA's MSW Conversion Activity was set up in 1986 to provide an infrastructure for sharing information and co-ordinating work in this area internationally. This Activity was extended in 1989 and currently a total of 9 nations participate in it.
To cope with the wide scope of the area (encompassing both biological and thermal processing of MSW) the Activity was divided into three subgroups or Expert Working Groups (EWGs). Each of these dealt with a distinct area of expertise:
- 1. •Downstream effects of source separation and screening of MSW
- 2. •Sampling and analytical protocols
- 3. •Landfill gas
In addition to these groups a central secretariat based at Harwell (UK) has provided guidance, established and administered databases of contacts and produced a series of national reports.
This paper describes the achievements of the Activity and discusses work proposed for the future. 相似文献
6.
7.
8.
国产轻油预转化催化剂与进口催化剂相比,具有性能相当、价格低廉、供应方便等优势。国产预转化催化剂需在较高的液空速、温度较低的条件下实现烃类转化反应,生成含甲烷60%以上的富气。采用国产催化剂能明显反映性能价格比。文章对两种催化剂进行了工业应用比较和分析。 相似文献
9.
10.
Linear oligosiloxanes functionalized with bulky side chain tris(trimethylsilyl)hexyl (TTSH) substituents were transformed into cross-linked materials by UV 193 nm excimer pulsed laser ablation. The process occurred without any catalyst, by reactions of radicals formed in UV laser induced photolysis of side tris(trimethylsilyl)hexyl groups. Chemical changes were monitored by FTIR, LC/UV, GC/MS and solubility tests. 相似文献