首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   6383篇
  免费   343篇
  国内免费   313篇
电工技术   208篇
技术理论   1篇
综合类   1024篇
化学工业   300篇
金属工艺   62篇
机械仪表   227篇
建筑科学   748篇
矿业工程   1802篇
能源动力   84篇
轻工业   253篇
水利工程   32篇
石油天然气   114篇
武器工业   6篇
无线电   161篇
一般工业技术   200篇
冶金工业   449篇
原子能技术   5篇
自动化技术   1363篇
  2024年   1篇
  2023年   26篇
  2022年   76篇
  2021年   100篇
  2020年   154篇
  2019年   105篇
  2018年   106篇
  2017年   106篇
  2016年   141篇
  2015年   176篇
  2014年   381篇
  2013年   374篇
  2012年   378篇
  2011年   522篇
  2010年   403篇
  2009年   393篇
  2008年   362篇
  2007年   486篇
  2006年   513篇
  2005年   430篇
  2004年   371篇
  2003年   359篇
  2002年   240篇
  2001年   170篇
  2000年   137篇
  1999年   154篇
  1998年   80篇
  1997年   63篇
  1996年   60篇
  1995年   45篇
  1994年   29篇
  1993年   39篇
  1992年   23篇
  1991年   12篇
  1990年   4篇
  1989年   2篇
  1988年   2篇
  1986年   2篇
  1985年   2篇
  1984年   3篇
  1983年   2篇
  1981年   1篇
  1980年   2篇
  1979年   1篇
  1977年   1篇
  1976年   2篇
排序方式: 共有7039条查询结果,搜索用时 0 毫秒
1.
企业试图完成数字化转型,这是在竞争中谋求发展的必经之路。文章率先进行数字化转型特征、策略的概念分析,而后总结以此为背景的能力模型、企业管理能力与技术能力,最终以某公司案例完成体系构建与应用的阐述。  相似文献   
2.
地表建构筑物位于在生产矿山地表开采移动范围内,如果按照一般圈定地表移动范围原则判断建构筑物的安全可靠性,结果是不安全或者预留保安矿柱可保证安全。为分析地表移动带范围内建构筑物安全可靠性,采用FLAC3D软件建立数值模拟模型,对矿区地表移动进行分析研究,并结合建构筑物的破坏等级评判标准,可以更加合理地判断地表移动范围内建构筑物的安全可靠性,对存在相似条件的矿山具有一定的借鉴意义。  相似文献   
3.
从黄柏河东支流域磷矿山绿色开发要求出发,基于地表水环境系统和矿业开采的耦合影响作用,开展了磷矿山开采对黄柏河东支的水环境的影响研究。通过定量和定性分析,在磷矿山开采过程中对黄柏河东支的各种影响因素中,矿井涌水(占比为43.19%)、尾渣淋溶水(占比为15.51%)、矿废石淋溶水(占比为14.64%)和生产废水(占比为10.84%)为磷矿山开采对黄柏河东支水环境的主要影响因素,尤其是矿井涌水携带的总污染物量大,影响占比接近50%。该研究影响分析为黄柏河东支水环境的治理提供有力指引支撑。  相似文献   
4.
Numerical simulation techniques such as Finite Element Analyses are essential in today's engineering design practices. However, comprehensive knowledge is required for the setup of reliable simulations to verify strength and further product properties. Due to limited capacities, design-accompanying simulations are performed too rarely by experienced simulation engineers. Therefore, product models are not sufficiently verified or the simulations lead to wrong design decisions, if they are applied by less experienced users. This results in belated redesigns of already detailed product models and to highly cost- and time-intensive iterations in product development.Thus, in order to support less experienced simulation users in setting up reliable Finite Element Analyses, a novel ontology-based approach is presented. The knowledge management tools developed on the basis of this approach allow an automated acquisition and target-oriented provision of necessary simulation knowledge. This knowledge is acquired from existing simulation models and text-based documentations from previous product developments by Text and Data Mining. By offering support to less experienced simulation users, the presented approach may finally lead to a more efficient and extensive application of reliable FEA in product development.  相似文献   
5.
翟艳东 《今日消防》2021,6(8):109-111
步入新时代,我国经济实现了跨越式发展,企业面临着更多的发展机遇与挑战,但只有牢牢守住"安全生产"这一警戒线,一切生产经营活动才能真正创造经济价值.现介绍一起电镀企业失火事故,通过分析认定事故原因,并结合类似事故案例,探寻事故频发的深层原因,提出有效的预防对策和措施,希望引发从事电镀生产及安全管理、消防工作人员的深度思考,提供可借鉴的有益经验,为企业安全生产保驾护航.  相似文献   
6.
Oil shale is an organic-rich, fine-grained sedimentary rock, containing kerogen, from which liquid hydrocarbons (called shale oil) can be produced. The oil shale deposits in the Tigray region are found in the northern parts of Ethiopia, Eastern Africa. They are of Upper Paleozoic in age, existing as remnants of the Cretaceous erosion period, underlain by tillites and overlain by sandstones. They were formed during the glacial retreat followed by marine deposition of shales in a basin created by the enormous load of the glaciers. The Ethiopian-Tigray oil shale deposits cover an area extending over approximately 30 km2, with an average mineable bed-thickness of 55 m, showing on the upper part inter-beds and laminations of shaley limestones. The oil shale resources in this region are estimated to be approximately 4 billion tonnes. The exploitation of the Ethiopian-Tigray oil shale deposits is an excellent alternative to fulfill the fuel and other petroleum products’ demand of Ethiopia. This study sheds light on the oil shale resources in the Ethiopian region of Tigray, as they are fairly investigated, regarding their geological characterization, and future strategies for their exploration and exploitation potential. In addition, the oil shale deposits in Jordan are also moderately investigated, as Jordan is considered a promising country for shale oil, taking into account that Jordan has no other hydrocarbon resources (such as crude oil and natural gas), unlike many other countries in the MENA (Middle East and North Africa) region, as MENA sets on “seas” of oil and natural gas. Furthermore, oil shale in the USA is also briefly investigated, as the USA is being the world’s largest country of oil shale resources and reserves. Also, some other issues related to the oil shale industry are investigated, such as economics, extraction technologies of shale oil, and the environmental impacts.  相似文献   
7.
分析非建设属性类国有企业开展基建项目时存在的优势和劣势,提出非建设属性类国有企业采用全过程工程咨询的实施策略,包括实施模式,委托阶段、委托方式、项目后评价四个方面。以某烟草企业经营业务用房建设项目为例,分析非建设属性类国有企业采用传统建设模式开展基建项目存在的问题和采用全过程工程咨询模式的优势,为非建设属性类国有企业采用全过程工程咨询提供参考借鉴。  相似文献   
8.
Recurrently the question arises if efforts in food safety management system (FSMS) have resulted in effective systems in animal-based food production systems. The aim of this study was to gain an insight in the performance of FSMS in European animal-based food production companies in view of their typical context characteristics. Hundred European companies (from Belgium, Spain, The Netherlands, Greece, Italy, and Hungary) varying in company size, and producing different types of fresh and processed animal-derived products (dairy, beef/lamb, poultry, and pork) were assed using a diagnostic instrument. Results indicated that most participating companies adapted adequately their food safety management systems to the riskiness of their context characteristics resulting in rather good safety output scores. Only a small group have overall basic systems and operate in a moderate or moderate-high risk context, which was reflected in lower safety output scores. Companies tend to invest first in the control strategies whereas assurance activities such as verification and validation seem to require more time and effort to achieve advanced levels. Our study demonstrated that also small and medium enterprises managed to have advanced systems, and achieve a good safety output. However, their typical organisational characteristics such as less resources (educated staff, laboratory facilities, time), more restricted formalisation (restricted use of procedures and formal meetings), limited information systems, but more stable workforce, might require more tailored support from government and/or branch organisations to develop towards advanced systems in the case of high-risk products and processes. More in-depth studies to successful SMEs could give insight in best practices to improve FSMS performance.  相似文献   
9.
该文分析了加强综采工作面超前支护的必要性,对传统的综采工作面超前支护技术存在的不足进行了分析;就如何加强新型综采工作面超前支护技术的应用进行了探讨。  相似文献   
10.
史海平  王帅 《现代矿业》2020,36(7):60-63
港里矿围岩软弱破碎,随开采深度延伸,地压显现越来越剧烈,严重影响港里矿正常回采。为研究港里矿软破围岩采矿,分析了影响采矿正常进行的因素和机理,调整采矿的顺序,使港里矿软破围岩采矿的困难得到根本扭转,保证了采矿生产的正常进行,选择围岩稳固及充分卸压部位布置斜坡道和联巷、优先回采围岩破碎的高应力区是地压管理的关键问题。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号