全文获取类型
收费全文 | 7244篇 |
免费 | 195篇 |
国内免费 | 91篇 |
专业分类
电工技术 | 171篇 |
综合类 | 645篇 |
化学工业 | 1283篇 |
金属工艺 | 354篇 |
机械仪表 | 561篇 |
建筑科学 | 120篇 |
矿业工程 | 136篇 |
能源动力 | 590篇 |
轻工业 | 397篇 |
水利工程 | 35篇 |
石油天然气 | 2562篇 |
武器工业 | 18篇 |
无线电 | 54篇 |
一般工业技术 | 225篇 |
冶金工业 | 98篇 |
原子能技术 | 22篇 |
自动化技术 | 259篇 |
出版年
2024年 | 3篇 |
2023年 | 46篇 |
2022年 | 62篇 |
2021年 | 104篇 |
2020年 | 156篇 |
2019年 | 138篇 |
2018年 | 93篇 |
2017年 | 155篇 |
2016年 | 163篇 |
2015年 | 193篇 |
2014年 | 327篇 |
2013年 | 350篇 |
2012年 | 314篇 |
2011年 | 486篇 |
2010年 | 364篇 |
2009年 | 307篇 |
2008年 | 229篇 |
2007年 | 298篇 |
2006年 | 310篇 |
2005年 | 309篇 |
2004年 | 266篇 |
2003年 | 326篇 |
2002年 | 257篇 |
2001年 | 299篇 |
2000年 | 388篇 |
1999年 | 335篇 |
1998年 | 245篇 |
1997年 | 233篇 |
1996年 | 204篇 |
1995年 | 175篇 |
1994年 | 117篇 |
1993年 | 83篇 |
1992年 | 71篇 |
1991年 | 40篇 |
1990年 | 12篇 |
1989年 | 12篇 |
1988年 | 10篇 |
1987年 | 5篇 |
1986年 | 8篇 |
1985年 | 10篇 |
1984年 | 10篇 |
1983年 | 8篇 |
1982年 | 5篇 |
1981年 | 4篇 |
排序方式: 共有7530条查询结果,搜索用时 15 毫秒
61.
文章在阐述我国石油价格形成机制的演变过程的基础上,针对我国目前石油定价机制所导致的诸如石油价格变动滞后以及由此带来的市场信号失灵等问题思考了相应的改革对策,提出了调整政府价格管理职能、建立平等竞争的市场规则、完善稳定油价的调控体系以及加快建立石油战略储备等7个方面的建议。 相似文献
62.
根据江汉松滋油田地层泥页岩的矿物组成、微观结构及理化性能资料.研究出了适于该油田的硅钾基防塌钻井液体系的基本配方.评价了其防塌性能、抗钻屑污染能力及抗温能力.探讨了其防塌机理。现场应用表明.该体系维护容易.防塌效果明显。 相似文献
63.
本文全面分析了DH80—16型离心压缩机可倾轴瓦油封漏油的原因,并介绍了可倾轴瓦油封漏油问题的解决及具体实施方案。 相似文献
64.
Raphaëlle Savoire Jean‐Louis Lanoisellé Hélène Ducatel Eugène Vorobiev 《European Journal of Lipid Science and Technology》2008,110(8):725-734
Seven linseed varieties were harvested at seven times before complete maturity. Microscale oilseed expressions were subsequently carried out on it. A pressure of 10 MPa was applied for 1 h under uniaxial stress. The results were characterized in terms of oil, water and mucilage content, harvest date and oil yield. The piston displacement versus time (creep curves) was described by a four‐Kelvin‐Voigt elements viscoelastic model. Parameters were derived from the model, such as the mechanical properties of seeds (compressibility moduli), showing that the viscoelastic model fits well the experimental data (R² ≈ 0.999). The modeling parameters were combined with some biochemical data in order to predict the kinetics of oil extraction. 相似文献
65.
66.
67.
A generalized kinematic viscosity-temperature correlation for undefined liquid heavy petroleum fractions has been developed to represent the data for a wide range of temperature from 100°C to 200°C. The correlation is based on the experimental kinematic viscosity data of true boiling point fractions of four Arabian crude oils. The characterization property required for estimation is 50% boiling point. The proposed correlation fits the experimental data with an overall absolute error of 6.1%. Experimental measurements of kinematic viscosity of heavy true boiling point fractions of Arabian crude oils were also obtained in order to develop the proposed correlation. 相似文献
68.
A review of literature about the effect of oil pockets on improvement of sliding elements tribological performance as well as about the changes of surface topography during “zero-wear” process is shown. The paper presents also the results of experimental investigations done in the Department of Manufacturing Processes and Production Organisation of Rzeszow University of Technology, connected with the creation of oil pockets on sliding surfaces. In order to simulate a deterministic surface a program for the visualisation of pits was written. The procedures for assessment of the oil pocket size of specific shape and oil pockets coverage are presented. The tendencies of changes of surface topography and oil pockets dimensions during “zero-wear” process are also described. 相似文献
69.
介绍了在运输部信息平台中实现油量实时显示的过程。油量传感器产生的电流模拟信号分成两路,一路传给无纸记录仪,另一路经过电压转变后送至信息平台的状态监测仪,经过状态监测仪的G2002B板处理后通过串口传给工控机,在信息平台上实现油量的实时显示,作用除了提醒司机适时加油以外,更重要的是判断机车作业的油耗情况。 相似文献
70.
M.A.K. Lodhi 《Energy Conversion and Management》1996,37(12):1677-1694
Solar ponds are probably the simplest technology available for the useful conversion of solar energy. The basic technology is proven. Solar ponds have been shown to be technically feasible and economically viable for many applications, particularly for thermal use. The electrical conversion and use of solar energy via solar ponds is still questionable, in general, for economic viability. By putting the untapped sources together in the South Plains region, it looks promising economically both for thermal and electrical conversions and applications. There are a number of alkaline lake basins randomly scattered in the South Plains region of the U.S.A. In that area, there are thousands of crude oil producing wells that produce brine in abundance. The selection of suitable alkaline lake basins as a solar pond site and as depository sites of brine from oil wells and the using of this brine and salty water from alkaline lakes makes the solar pond economically viable for both thermal and electrical demands in the area. 相似文献