全文获取类型
收费全文 | 5910篇 |
免费 | 574篇 |
国内免费 | 250篇 |
专业分类
电工技术 | 116篇 |
综合类 | 477篇 |
化学工业 | 281篇 |
金属工艺 | 46篇 |
机械仪表 | 57篇 |
建筑科学 | 2040篇 |
矿业工程 | 1733篇 |
能源动力 | 152篇 |
轻工业 | 231篇 |
水利工程 | 895篇 |
石油天然气 | 309篇 |
武器工业 | 1篇 |
无线电 | 25篇 |
一般工业技术 | 60篇 |
冶金工业 | 183篇 |
原子能技术 | 5篇 |
自动化技术 | 123篇 |
出版年
2024年 | 13篇 |
2023年 | 49篇 |
2022年 | 145篇 |
2021年 | 199篇 |
2020年 | 232篇 |
2019年 | 139篇 |
2018年 | 126篇 |
2017年 | 139篇 |
2016年 | 188篇 |
2015年 | 196篇 |
2014年 | 621篇 |
2013年 | 447篇 |
2012年 | 619篇 |
2011年 | 537篇 |
2010年 | 427篇 |
2009年 | 376篇 |
2008年 | 339篇 |
2007年 | 365篇 |
2006年 | 294篇 |
2005年 | 224篇 |
2004年 | 203篇 |
2003年 | 191篇 |
2002年 | 133篇 |
2001年 | 114篇 |
2000年 | 98篇 |
1999年 | 73篇 |
1998年 | 53篇 |
1997年 | 49篇 |
1996年 | 32篇 |
1995年 | 29篇 |
1994年 | 20篇 |
1993年 | 15篇 |
1992年 | 5篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 8篇 |
1986年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1979年 | 5篇 |
1959年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有6734条查询结果,搜索用时 15 毫秒
1.
Effective management of the risks associated with acid rock drainage (ARD) requires the ability to identify material with a potential to generate ARD reliably. With the increasing prevalence of quantitative mineralogy (Quantitative XRD, auto-SEM), opportunity exists to use mineralogy at all stages in ARD characterisation and prediction. This study uses a mineralogical approach across the head grade samples and the residues obtained under leach conditions of several common ARD characterisation tests (Acid Neutralising Capacity, Net Acid Generation), as well as the University of Cape Town (UCT) biokinetic test to evaluate the extent to which acid-neutralising minerals react. The results show the contribution of the carbonates to the acid neutralising capacity, as well as the partial dissolution of intermediate weathering silicate minerals such as chlorite and mica. 相似文献
2.
3.
该工艺技术是在原三联作(TCP+MFE+JET)基础上,根据大港油田勘探试油(测试)的需要,研制开发出的又一新技术,与原三联作相比,一趟管柱不但完成求产、测压、泵排工作,而且还能进行酸化等措施,提高了资料品质,减少了作业成本。经过6井次现场应用,全部达到了设计要求,取得了工艺、资料、成本、速度的较大进步,具有较高推广应用价值。 相似文献
4.
S. David Graber 《Canadian Metallurgical Quarterly》2004,130(1):67-80
Numerous types of pipes and channels with spatially increasing flows in environmental engineering applications are identified by type and function and referred to as collection conduits. An overview of methods for designing and analyzing collection conduits is provided. Full conduits with nonuniform and uniform inflow are first considered. Dimensional analysis is then employed to demonstrate the relationship between variables for open channels; that leads to the identification of possibilities for generalized numerical solutions. Prior collection conduit applications are discussed within the framework of the dimensional analysis (which also pertains to some constant-flow applications). A previously unpublished generalized numerical solution for rectangular collection conduits is presented. Subsurface drains are addressed with particular emphasis, including the use of numerical methods to develop a new generalized chart and relation to other design methods. Among the important conclusions for subsurface drains is that the somewhat common practice of using Manning’s equation alone for such problems is not generally adequate. Examples and practical design suggestions are included, and the use of computer-based numerical methods is discussed more generally. 相似文献
5.
Glass columns (length 50 cm, i.d. 4 cm) containing 900 g of uranium ore waste were subjected to a three-step process: (1) acid drainage generation, (2) neutralization and precipitation treatment and, again, (3) acid drainage generation. In the first acid generation step, lasting about one year, different variables (pyrite addition, inoculation and irrigation solution) were tested by measuring effluent pH, redox potential, total iron and sulphate. Conditions of acid generation were satisfactorily reproduced, reaching stable pH values around 2.0 that were determined mainly by pyrite addition and the type of irrigation solution used (distilled water or ferrous sulphate). The neutralization and precipitation treatment consisted of alternating irrigations of a neutralizing solution (CaO saturated plus NaOH) and a precipitating solution (ferric sulphate saturated). This treatment caused accumulation of basic iron sulphate and iron oxide precipitates according to SEM studies. After this treatment, the barrier effect created by the reaction products was checked, using irrigation solutions similar to the first step. The effluents collected showed higher pH and lower redox potential, total iron and sulphate values than those observed before the treatment, evidencing inhibition of acid drainage generation. 相似文献
6.
本文通过分析筼筜湖的自然概况、防汛排涝系统设施及实际运行等资料,提出进一步提高筼筜湖防汛排涝能力的对策。 相似文献
7.
屋顶绿化配套技术研究 总被引:10,自引:0,他引:10
从绿化植物选择、种植土的配制、防排水措施,养护管理等方面介绍了“屋顶绿化配套技术研究课题”的主要成果。 相似文献
8.
通过铝箔项目的工程实例,详细介绍了铝箔项目给排水专业设计的主要构成,并总结了几点设计体会,可供有关专业设计人员借鉴、参考。 相似文献
9.
本文采用综合修正系数取代规范建议的单一折减系数,用渗流场分析方法确定作用在引黄入晋南干线7#隧洞衬砌上的外水压力。由己知钻孔水位及泉水位反演出各地层的渗透张量及地表入渗强度求得初始渗流场。衬砌外水压力分析中考虑了衬砌混凝土的渗透性以及排水、灌浆等工程措施的影响。根据分析结果,提出了系统排水孔布置的建议,得出了在相应的排水减压措施下衬砌厚度由原设计35cm减至25cm,这一建议已被采用,取得了巨大经济效益。 相似文献
10.
以往对电站技术供排水系统大都未进行水力平差计算,致使一些实际电站的供排水系统达不到预期的效果,甚至影响机组的正常运行。据此,给出了供排水管网的平差计算方法,有利于正确评估电站管网,另外,提出了管网校核应注意的问题。 相似文献