全文获取类型
收费全文 | 63827篇 |
免费 | 5620篇 |
国内免费 | 2809篇 |
专业分类
电工技术 | 3378篇 |
技术理论 | 2篇 |
综合类 | 3328篇 |
化学工业 | 12849篇 |
金属工艺 | 1961篇 |
机械仪表 | 2276篇 |
建筑科学 | 3775篇 |
矿业工程 | 5832篇 |
能源动力 | 5565篇 |
轻工业 | 4496篇 |
水利工程 | 262篇 |
石油天然气 | 17916篇 |
武器工业 | 271篇 |
无线电 | 1264篇 |
一般工业技术 | 3268篇 |
冶金工业 | 3309篇 |
原子能技术 | 651篇 |
自动化技术 | 1853篇 |
出版年
2024年 | 208篇 |
2023年 | 833篇 |
2022年 | 1666篇 |
2021年 | 2227篇 |
2020年 | 2354篇 |
2019年 | 1950篇 |
2018年 | 1730篇 |
2017年 | 1820篇 |
2016年 | 2319篇 |
2015年 | 2230篇 |
2014年 | 3971篇 |
2013年 | 3815篇 |
2012年 | 4939篇 |
2011年 | 5079篇 |
2010年 | 3405篇 |
2009年 | 3322篇 |
2008年 | 2828篇 |
2007年 | 3581篇 |
2006年 | 3845篇 |
2005年 | 3183篇 |
2004年 | 2739篇 |
2003年 | 2419篇 |
2002年 | 2067篇 |
2001年 | 1887篇 |
2000年 | 1597篇 |
1999年 | 1271篇 |
1998年 | 969篇 |
1997年 | 847篇 |
1996年 | 661篇 |
1995年 | 549篇 |
1994年 | 442篇 |
1993年 | 319篇 |
1992年 | 258篇 |
1991年 | 204篇 |
1990年 | 176篇 |
1989年 | 161篇 |
1988年 | 60篇 |
1987年 | 45篇 |
1986年 | 41篇 |
1985年 | 33篇 |
1984年 | 30篇 |
1983年 | 21篇 |
1982年 | 18篇 |
1981年 | 61篇 |
1980年 | 35篇 |
1979年 | 7篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1973年 | 5篇 |
1951年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
富县探区三叠系延长组长6段普遍见到不同级别的油气显示,但试油未能获得工业油流.据分析,该区白垩纪末的抬升和翘倾运动使油气发生了第三次运移成藏,油、气、水重新分布并受储层物性控制.正确勾画出有利沉积相带、针对油藏特征采取更有效的工艺技术,是实现该区勘探突破的关键. 相似文献
102.
介绍了深圳市机动车发展现状,分别用趋势外推法、城市比较分析法和分类法预测了2010-2020年深圳市的机动车保有量,最后预测了机动车的油气需求量。 相似文献
103.
城市燃气管网GIS系统的开发 总被引:1,自引:1,他引:0
随着我国天然气工业的不断发展,对于城市天然气管网的智能化管理已经作为一个全新的课题出现在燃气企业里。过去所使用的MIS系统(Management Information System),无论从效率、准确度、智能程度上讲,都已经不能满足目前城市燃气管网的精确管理。因此地理信息系统(Geography Information System,简称GIS系统)作为一种新的计算机管理系统应运而生,其主要特点是:有精确的管理、有标准的地图提供直接判断、空间关系与实物对应明确、管理直观。文章以企业对管理系统的需求以及技术可行性为出发点,阐述了GIS系统应具有的基本性能;同时结合燃气工程技术的发展,对燃气GIS系统做了应用开发研究;此外还对现阶段部分燃气GIS信息系统的不足做出了分析。 相似文献
104.
David M. Scott Debendra K. Das Vijayagandeeban Subbaihaannadurai 《Petroleum Science and Technology》2006,24(8):895-909
A finite element scheme is presented to model the dissociation of gas hydrates in porous media by hot water injection. We show a complete derivation of the finite element formulation, including the associated mass and energy conservation equations capable of performing transient analysis of both conductive and convective heat transfer for gas and liquid flow in porous media. The scheme also includes the latent heat effect to accommodate the change of phase due to melting of hydrate. In the companion paper, Part II, this method is successfully applied to hydrate reservoirs. 相似文献
105.
Jan‐Chan Huang 《应用聚合物科学杂志》2003,90(3):671-680
A modified method is discussed that is based on Farooque and Deshpande's method to obtain polymer–polymer interaction parameters using inverse gas chromatography (IGC) data. In the Farooque and Deshpande method, the ratio of the difference of probe–polymer interaction parameters between two polymers and the probe volume [(χ12 ? χ13)/V1] is used as the abscissa. In the modified method, the ratio [(?2χ12 + ?3χ13)/V1] is used as the abscissa. Experimental data previously reported for a poly(?‐caprolactone)‐polyepichlorohydrin (PCL/PECH) blend and a poly(ethyl acrylate)‐poly(vinyl propionate) (PEA/PVPr) blend are analyzed. It is found that the slopes obtained by the new method had smaller deviations from the theoretical values than the Farooque and Deshpande method. The standard deviations of both slopes and intercepts obtained from the new method are also smaller. Using the new method, the polymer–polymer interaction parameters obtained from the intercept are negative numbers for the PCL/PECH system and very small positive numbers for PEA/PVPr. Explanations are given for the probe and concentration dependency of the polymer–polymer interaction parameters that are generally observed in IGC studies. A new method for selecting the best probe for calculating the interaction parameter is discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 671–680, 2003 相似文献
106.
107.
SF6气体绝缘电容式电压互感器研制 总被引:6,自引:0,他引:6
本文介绍西容公司新研制的一种完全无油化的SF6气体绝缘电容式电压互感器,提出了关键技术问题解决方案和产品绝缘结构的设计思路.并介绍了研制成功的110kV和220kV系列产品的结构、技术参数、性能指标、试验考核情况和产品特点. 相似文献
108.
As an alternative to previously developed catalytic FeCrAlloy fibre mat burners based on perovskite catalysts, new catalytic burners have been developed based on Pd catalyst on lantana-stabilised Al2O3 and different fibre structures (NIT100A, NIT100S and NIT200S by ACOTECH NV). All development steps are considered, shifting from catalyst preparation (based on combustion synthesis of γ-Al2O3) to the optimisation of lantana and Pd loadings, from the definitions of the best catalyst-deposition conditions (washcoating) to the catalytic burners performances, determined in an ad hoc developed combustion chamber. The results show almost half pollutants emissions and better performance compared to various non-catalytic counterparts, especially as far as CO and NOx emissions are concerned. Some flame instability problems were though registered, especially for one of the catalytic burner mattresses employed, at low specific power inputs and excesses of air (<375 kW/m2 and <12%, respectively). Further, PdO/Pd transition is shown to influence the dynamic behaviour of the catalytic burners. 相似文献
109.
110.
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