全文获取类型
收费全文 | 693篇 |
免费 | 7篇 |
国内免费 | 21篇 |
学科分类
工业技术 | 721篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 10篇 |
2021年 | 12篇 |
2020年 | 26篇 |
2019年 | 24篇 |
2018年 | 31篇 |
2017年 | 20篇 |
2016年 | 23篇 |
2015年 | 18篇 |
2014年 | 32篇 |
2013年 | 21篇 |
2012年 | 29篇 |
2011年 | 41篇 |
2010年 | 28篇 |
2009年 | 36篇 |
2008年 | 21篇 |
2007年 | 31篇 |
2006年 | 22篇 |
2005年 | 28篇 |
2004年 | 30篇 |
2003年 | 18篇 |
2002年 | 21篇 |
2001年 | 30篇 |
2000年 | 33篇 |
1999年 | 31篇 |
1998年 | 20篇 |
1997年 | 17篇 |
1996年 | 21篇 |
1995年 | 9篇 |
1994年 | 10篇 |
1993年 | 11篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有721条查询结果,搜索用时 15 毫秒
61.
露头碳酸盐岩旋回层序的识别与划分 总被引:5,自引:0,他引:5
在海相碳酸盐岩新区勘探中,露头层序地层学是一种重要的勘探手段。归纳了露头碳酸盐岩米级旋回层序的识别特征和划分依据,识别和测量了北京西山丁家滩剖面的米级旋回层序,并分析其垂直叠加型式,划分了长周期旋回层序。结果表明,通常是4~6个向上变厚并变浅的米级旋回层序构成一个五级旋回层序;4个总体向上变厚并变浅的五级旋回层序构成一个四级旋回层序;3~5个四级旋回层序构成一个更大级别的总体向上变厚变浅的序列。图1表1参6(邹冬平摘) 相似文献
62.
塔河油田奥陶系碳酸盐岩油藏堵水工艺技术浅谈 总被引:7,自引:0,他引:7
对塔河油田奥陶系碳酸盐岩油藏的储层特点进行了论述,并重点阐述了塔河油田堵水工艺的技术现状和需要重点研究的内容.对已经实施堵水的不同类型油井的现场试验效果进行了分析与评价,并在此基础上,通过对采用不同完井方式投产的油井所表现出的地层见水规律和出水原因的不同的分析,归纳出了几种较为典型的堵水地质模型,提出应根据不同的模型合理选择相应的堵水方式的建议. 相似文献
63.
Fractures and fractured zones require special attention while formulating a reservoir development plan. They may improve or hinder the oil production. Conductive fracture rocks may provide the required permeability to drain an oil saturated low permeability rock matrix. Low sweep efficiency of many oil reservoirs is the result of channelling of injected water through high permeability zones that are normally associated with naturally fractured systems in heterogeneous reservoirs. In this case, a substantial amount of effort needs to be focused on improving the distribution of injected water in the wellbore through different treatments, such as using gelling agents, cements, cross-linked polymer and emulsions. Other alternatives such as microbial and surfactant based methods have been proposed. This paper presents the results of research conducted on thermophilic bacteria that were obtained from UAE local environment. Coreflooding experiments were conducted on fractured single cores to show the effectiveness of microbial treatment. Different fracture angle orientations of 45°, 90°, and 180° relevant to the axis of the flow were investigated. The effect of matrix permeability on the treatment was also studied. A comparison between water flooding and microbial flooding of fractured systems was conducted. A non-invasive imaging technique—Scanning Electron Microscopy (SEM)—was employed to visualize changes on the surface of the fracture as a result of bacteria flow through the system. 相似文献
64.
湿式搅拌磨细磨重质碳酸钙的实践和微粉加工工艺 总被引:2,自引:0,他引:2
介绍了GSDM-400型超细盘式搅拌磨细磨不同产地重质碳酸钙的工艺实践,阐述了造纸涂布级重钙微粉的超细加工工艺,分析了各种工艺的特点和选择依据。 相似文献
65.
提出了一种孔隙性碳酸盐岩储集层分类的新方法,即模糊物元关联分析.实例表明与其他方法一致,并与实际相符,可推广使用. 相似文献
66.
67.
??The Ordovician carbonate rocks in the Gucheng area are the potential replacement zone for oil and gas exploration in the Tarim Basin. However, its sedimentary sequence has been less studied, which restricts the progress of oil and gas exploration in this area. In this paper, based on the cyclic changes of the carbon isotope value, together with the analysis of logging curves and well-seismic calibration,
the Ordovician carbonate strata were divided into 4 third-order sequences. According to the six types of microfacies (i.e. calcsparite cemented grain limestone, algal-cemented calcarenite, packstone, micrite limestone, medium-coarse crystalline dirty dolomite, and fine powder crystal dolomite) identified under microscopic observation of thin sections, the distribution and evolution law of sedimentary systems
in the sequence were analyzed. The following results are obtained. First, the platform margin–semi-restricted platform and platform margin–open platform sedimentary systems developed in this area. Both OSQ1 and OSQ2 are predominantly sea-level falling half-cycle sequences, and platform margin limestone and semi-restricted platform dolomite are dominant. Second, OSQ3 is predominantly sea-level rising half-cycle sequence. In the early stage of sea-level rising, platform margin–semi-restricted platform developed, and later platform margin-open platform developed. Third, OSQ4 is composed of sea-level rising half cycle and platform margin–open platform limestone developed. It is concluded that the sea-level rising/falling cycle controlled the distribution and evolution of sedimentary system in the sequences in this area. In the sea-level falling stage, semi-restricted platform best developed in OSQ1 and OSQ2, recording as the main horizons for the development of dolomite. 相似文献
68.
《Journal of Industrial and Engineering Chemistry》2014,20(3):961-971
The Au/CeO2–Fe2O3 prepared by deposition–precipitation were studied by steam reforming of methanol at a reaction temperature range of 200–400 °C. Complete methanol conversion was obtained at the optimal steam/methanol ratio of 2 at 400 °C. A high steam content strongly depressed both methanol conversion and hydrogen concentration since this led to a complex mechanism and the formation of carbonate and formate species. After pretreating with oxygen, the catalytic activity dramatically decreased with the presence of an inhomogeneous CexFe1−xO2 solid solution phase; the covering Au sites by the free α-Fe2O3 particles; and an agglomeration of both free α-Fe2O3 and Au particles. 相似文献
69.
Worldwide consumption of manganese is increasing, nevertheless huge amounts of manganese from hydrometallurgical processes still end up as waste since the recovery of manganese from multi-metal solutions at low concentrations is not considered feasible. Poor iron control typically prevents the production of high purity manganese. This work studies a number of precipitants in manganese recovery and iron separation from sulfate solutions. The precipitation reagents were compared from the point of view of selectivity and economy. Carbonate precipitation is a fast and effective method for the recovery of manganese from bulk solutions. Subsequent leaching of metal carbonate is also easier and consumes less acid than, for example, hydroxide or sulfide precipitates. In order to avoid gypsum formation, soda ash should be used instead of limestone. It was found that efficient selective iron removal from MnSO4 solutions is achieved with combined O2 or air oxidation and CaCO3 precipitation at pH >5.8 and at a redox potential of >200 mV. Effective mixing and sufficient retention time are essential to make the method technically efficient and economically feasible. 相似文献
70.
利用废弃蛋壳制备碳羟磷灰石(简称CHAP),并用作去除废水中Pb^2+的吸附剂。考查了pH值、吸附时间、温度、吸附剂用量以及Pb^2+初始浓度等因素对吸附效果的影响。结果表明:0.6g/L的CHAP对750mg/L的Pb^2+的去除率高达99.9%,吸附容量达到1243.75mg/g。CHAP对Pb^2+吸附的吸附等温线均符合Freundlich和Langmuir两种模式,从Freundlich方程中的常数1/n=0.0184可知,该吸附反应为吸热自发反应,且反应速率快。 相似文献