全文获取类型
收费全文 | 261104篇 |
免费 | 20574篇 |
国内免费 | 13290篇 |
专业分类
电工技术 | 16806篇 |
技术理论 | 51篇 |
综合类 | 36347篇 |
化学工业 | 28364篇 |
金属工艺 | 9692篇 |
机械仪表 | 14103篇 |
建筑科学 | 37390篇 |
矿业工程 | 14898篇 |
能源动力 | 7856篇 |
轻工业 | 14515篇 |
水利工程 | 13924篇 |
石油天然气 | 11134篇 |
武器工业 | 2497篇 |
无线电 | 17110篇 |
一般工业技术 | 18327篇 |
冶金工业 | 15423篇 |
原子能技术 | 2613篇 |
自动化技术 | 33918篇 |
出版年
2024年 | 801篇 |
2023年 | 2467篇 |
2022年 | 4748篇 |
2021年 | 5704篇 |
2020年 | 6054篇 |
2019年 | 5084篇 |
2018年 | 4815篇 |
2017年 | 5792篇 |
2016年 | 6973篇 |
2015年 | 7817篇 |
2014年 | 14469篇 |
2013年 | 13138篇 |
2012年 | 17199篇 |
2011年 | 18294篇 |
2010年 | 14590篇 |
2009年 | 15253篇 |
2008年 | 14275篇 |
2007年 | 18789篇 |
2006年 | 17824篇 |
2005年 | 15631篇 |
2004年 | 13307篇 |
2003年 | 12001篇 |
2002年 | 9891篇 |
2001年 | 8374篇 |
2000年 | 7065篇 |
1999年 | 5773篇 |
1998年 | 4356篇 |
1997年 | 3827篇 |
1996年 | 3549篇 |
1995年 | 3011篇 |
1994年 | 2686篇 |
1993年 | 2010篇 |
1992年 | 1784篇 |
1991年 | 1324篇 |
1990年 | 1163篇 |
1989年 | 1028篇 |
1988年 | 821篇 |
1987年 | 564篇 |
1986年 | 423篇 |
1985年 | 351篇 |
1984年 | 331篇 |
1983年 | 240篇 |
1982年 | 214篇 |
1981年 | 165篇 |
1980年 | 130篇 |
1979年 | 111篇 |
1978年 | 63篇 |
1977年 | 72篇 |
1976年 | 55篇 |
1975年 | 55篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Reliability based criteria are quite popular for optimal sensor network design. We present a modified definition of system reliability for sensor network design for two applications: reliable estimation of variables in a steady state linear flow process, and reliable fault detection and diagnosis for any process. Unlike the weakest-link based definition of system reliability in the literature, the proposed definition considers the entire system and is consistent with the reliability concept used in classical reliability literature. For each application, dual approaches for defining system reliability are proposed, and their analogy with the reliability problem in the classical reliability literature is established. Using examples and stochastic simulations, the advantage of using the proposed system reliability in contrast to the existing definition is illustrated. Part II of this series of articles presents methods for efficient generation of the system reliability function and its use in optimization-based approaches for designing optimal sensor networks. 相似文献
52.
与传统比例-积分-微分(PID)控制方法相比,滑模控制(SMC)方法可以比较容易地将不确定性纳入控制器设计中,从而增强系统的鲁棒性。探索了SMC技术在运载器主动段姿态控制中的工程应用,首先通过分析基于趋近律的SMC系统,提出了降低不连续切换项系数的需求,然后研究了基于干扰上界的SMC方法。三通道小偏差仿真结果验证了两种方法的控制效果,表明第2种控制器的鲁棒性更好,稳态误差小,同时发动机喷管摆角需求较小。 相似文献
53.
泛在电力物联网是物联网在电力领域的具体体现,建设泛在电力物联网是推进"三型两网"建设的关键环节,也是实现能源转型的必要手段。阐述了泛在电力物联网的定义,从供电公司角度出发,根据北京经济技术开发区实际情况,讨论了依托地区特点的泛在电力物联网实施策略和实际应用场景,分析了可能遇到的问题。得出结论:随着泛在电力物联网的深入建设,供电公司能够为电力客户提供多元化服务,提高客户满意度;地市供电公司能够依托泛在电力物联网开展更多电力相关业务;泛在电力物联网的安全性、实用性、有效性是发展面临的首要问题。 相似文献
54.
55.
《Calphad》2020
This publication contains the thermodynamic results received by the drop calorimetry method. The experiments were conducted for four different cross sections, at the temperature of 1080 K. The investigated alloys were as follows: (Ga0.75Li0.25)1-xGex, (Ge0.50Li0.50)1-xGax, (Ga0.50Li0.50)1-xGex, (Ga0.25Li0.75)1-xGex. The mixing enthalpy changes measured for all four cross sections of the Ga-Ge-Li system are characterized by negative deviations from the ideal solutions. The Muggianu model with the ternary interaction parameters was applied to elaborate the experimental data of the mixing enthalpy change with the use of the optimized thermodynamic parameters of the binary systems available in the literature. 相似文献
56.
通过分析A公司在研发项目范围管理中所存在问题,提出研发项目范围管理的方法及其在C产品的应用实例,通过运用研发项目范围管理的工具和方法,改善产品开发流程,从而缩短新产品开发周期,提高响应市场的速度,并提高企业研发项目的管理能力。 相似文献
58.
Non-convex of an optimal power dispatch problem makes it difficult to guarantee the global optimum. This paper presents a convex relaxation approach, called the Moment Semidefinite Programming (MSDP) method, to facilitate the search for deterministic global optimal solutions. The method employs a sequence of moments, which can linearize polynomial functions and construct positive semidefinite moment matrices, to form an SDP convex relaxation for power dispatch problems. In particular, the rank of the moment matrix is used as a sufficient condition to ensure the global optimality. The same condition can also be leveraged to estimate the number of global optimal solution(s). This method is effectively applied to {0,1}-economic dispatch (ED) problems and optimal power flow (OPF) problems. Simulation results showed that the MSDP method is capable of solving {0,1}-ED problems with integer values directly, and is able to identify if more than one global optimal solutions exist. In additional, the method can obtain rank-1 moment matrices for OPF’s counterexamples of existing SDP method, this ensures the global solution and overcomes the problem that existing SDP method cannot meet the rank-1 condition sometimes. 相似文献
59.
Salman M.A. Salman 《国际水资源开发杂志》2015,31(1):4-16
The United Nations Watercourses Convention entered into force on 17 August 2014, following a long and complex journey that dates back to 1970 when the UN referred the matter to its legal arm, the International Law Commission. This article follows the Convention through that long and turbulent road, examines its main provisions and analyses the reasons for the delay of its entry into force. It concludes by answering the question of why entry into force of the Convention should indeed matter. 相似文献
60.