全文获取类型
收费全文 | 17334篇 |
免费 | 1882篇 |
国内免费 | 843篇 |
专业分类
电工技术 | 229篇 |
技术理论 | 1篇 |
综合类 | 1146篇 |
化学工业 | 2890篇 |
金属工艺 | 979篇 |
机械仪表 | 347篇 |
建筑科学 | 1175篇 |
矿业工程 | 2202篇 |
能源动力 | 270篇 |
轻工业 | 4660篇 |
水利工程 | 220篇 |
石油天然气 | 1179篇 |
武器工业 | 185篇 |
无线电 | 407篇 |
一般工业技术 | 979篇 |
冶金工业 | 1646篇 |
原子能技术 | 125篇 |
自动化技术 | 1419篇 |
出版年
2024年 | 102篇 |
2023年 | 291篇 |
2022年 | 497篇 |
2021年 | 588篇 |
2020年 | 673篇 |
2019年 | 563篇 |
2018年 | 546篇 |
2017年 | 657篇 |
2016年 | 629篇 |
2015年 | 704篇 |
2014年 | 896篇 |
2013年 | 953篇 |
2012年 | 1109篇 |
2011年 | 1267篇 |
2010年 | 991篇 |
2009年 | 948篇 |
2008年 | 826篇 |
2007年 | 1134篇 |
2006年 | 955篇 |
2005年 | 848篇 |
2004年 | 686篇 |
2003年 | 592篇 |
2002年 | 512篇 |
2001年 | 467篇 |
2000年 | 437篇 |
1999年 | 375篇 |
1998年 | 296篇 |
1997年 | 241篇 |
1996年 | 235篇 |
1995年 | 194篇 |
1994年 | 187篇 |
1993年 | 107篇 |
1992年 | 127篇 |
1991年 | 91篇 |
1990年 | 77篇 |
1989年 | 50篇 |
1988年 | 40篇 |
1987年 | 31篇 |
1986年 | 24篇 |
1985年 | 25篇 |
1984年 | 22篇 |
1983年 | 15篇 |
1982年 | 17篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1961年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
An optimization strategy has been applied to describe the chemical composition at the furnace bottom in the Kraft recovery boiler of a pulp production process. The concentrations of each involved chemical species were calculated through an optimization approach, minimizing the Gibbs free energy of the system. Various systems were proposed and tested, assuming different chemical species and phases number. Because serious initialization problems were found at this stage for some of the proposed systems, an optimization heuristic method (PSO) was used for the first approach to the problem. Once the appropriate phases number and chemical species in the system were determined, the initialization problems disappeared and the use of a deterministic optimization method (SQP) became viable. The proposed approach has shown to be satisfactory to reproduce industrial data and also data reported in the open scientific literature. 相似文献
42.
基于本体的可信软件演化框架模型* 总被引:1,自引:0,他引:1
为系统化地考虑开放环境对软件可信性的影响和驱动作用,提出了一种基于本体空间并支持动态演化的框架模型。该模型采用本体空间的方法解决用户、系统和环境三者之间交互的语义问题,在此基础上,通过预定义的规则对软件行为的可信性和自主调整的必要性进行评估,依据评估结果从微观层次的规约制导和宏观层次的人机协同在软件生命周期内对其调整、配置与修正。应用实例及测试结果验证了该框架模型的有效性与可行性。 相似文献
43.
为推广预应力混凝土箱梁结构在桥梁方面的应用研究,结合英屿沟Ⅱ号天桥实例,介绍了该组合结构在桥梁方面具体应用的设计思路,介绍了英屿沟Ⅱ号天桥波形钢腹板PC组合箱梁桥主梁结构、预应力体系、波形钢腹板、连接件、防腐、施工流程等的设计,为波形钢腹板PC组合箱梁结构应用于桥梁工程提供了设计经验. 相似文献
44.
Frederico Lopes Flavia C. Delicato Thais Batista Everton Cavalcante Thiago Pereira Paulo F. Pires 《International Journal of Parallel, Emergent and Distributed Systems》2014,29(2):178-212
In this paper, we present OpenCOPI (Open COntext Platform Integration), a Service-Oriented Architecture-based middleware platform that supports the integration of services provided by distinct sources, ranging from services offered by simple systems to more complex services provided by context-provision middleware. OpenCOPI offers selection and composition mechanisms to, respectively, select and compose services provided by different sources, considering applications of both Quality of Service and Quality of Context requirements. It also offers an adaptation mechanism that enables to adapt the application execution due to service failures, service quality fluctuation and user mobility. OpenCOPI allows the definition of applications in a higher abstraction level by the specification of a semantic workflow that contains abstract activities. This paper illustrates the use of OpenCOPI in an application from the Gas & Oil Industry and it also shows the evaluation of the main mechanisms of OpenCOPI: the service selection, composition, adaptation and workflow execution. 相似文献
45.
针对云制造模式下快速选择和组织相关制造资源、保证制造任务执行的问题,提出一种面向制造任务的云制造虚拟车间构造方法。该方法将制造过程抽象为制造任务执行链,链中的节点对应制造设备云服务或检验云服务,链中的有向边对应物流云服务;并通过行业域、地域和类型域来组织管理云服务,以构造规模较小的候选云服务集,同时减少功能匹配、性能匹配、价格匹配和时间匹配的计算量,达到快速构建云制造虚拟车间的目的。算例分析表明,相比其他方法,该方法能够在更短的时间内完成云服务的选择,并保证所选云服务的服务质量(QoS)在相关域中是更好的。 相似文献
46.
本文研究了车轮踏面的热裂和磨损机理,结果表明,车轮热裂主要与其含碳量和硬度有关;在使用合成闸瓦时,车轮踏面的磨损率与新形成的“白层”(马氏体)的断裂韧性有关。研制的抗热裂耐磨车轮(55SiMn)取得了明显的运用效果。 相似文献
47.
Programmers build large‐scale systems with multiple languages to leverage legacy code and languages best suited to their problems. For instance, the same program may use Java for ease of programming and C to interface with the operating system. These programs pose significant debugging challenges, because programmers need to understand and control code across languages, which often execute in different environments. Unfortunately, traditional multilingual debuggers require a single execution environment. This paper presents a novel composition approach to building portable mixed‐environment debuggers, in which an intermediate agent interposes on language transitions, controlling and reusing single‐environment debuggers. We implement debugger composition in Blink, a debugger for Java, C, and the Jeannie programming language. We show that Blink is (i) simple: it requires modest amounts of new code; (ii) portable: it supports multiple Java virtual machines, C compilers, operating systems, and component debuggers; and (iii) powerful: composition eases debugging, while supporting new mixed‐language expression evaluation and Java native interface bug diagnostics. To demonstrate the generality of interposition, we build prototypes and demonstrate debugger language transitions with C for five of six other languages (Caml, Common Lisp, C#, Perl 5, Python, and Ruby) without modifications to their debuggers. Using real‐world case studies, we show that diagnosing language interface errors require prior single‐environment debuggers to restart execution multiple times, whereas Blink directly diagnoses them with one execution. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
48.
49.
Kathy Shields 《国际互联网参考资料服务季刊》2013,18(3-4):207-218
In Spring 2012, instruction librarians collaborated with first year composition (FYC) faculty to study students’ research habits as they related to writing. We collected process narratives from students in the introductory FYC course at the beginning and end of the fall semester, and a group of librarians and FYC faculty coded them together. Although we did not achieve one of our initial research goals, we still gained valuable insight into how our students perceive sources and the research process. We applied what we learned to create new instructional materials and developed a valuable relationship with FYC faculty. 相似文献
50.
针对不同的地表覆盖条件,研究基于Hyperion星载高光谱数据的砂页岩型铜矿信息提取方法。首先对Hyperion L1级数据进行波段筛选、坏线修复、大气纠正和几何纠正等预处理,然后分别针对不同的植被覆盖情况使用不同的信息提取方法。在岩石裸露区,直接使用光谱角制图法;在植被覆盖区,使用铜金属离子的积累导致的植被生理异常作为间接标志来识别铜矿信息,生理异常使用高光谱植被指数来计算。结果表明,综合使用这两种方法的互补信息能够便于提取复杂地表覆盖情况下的铜矿信息。 相似文献