全文获取类型
收费全文 | 639篇 |
免费 | 42篇 |
国内免费 | 97篇 |
专业分类
电工技术 | 5篇 |
综合类 | 38篇 |
化学工业 | 23篇 |
金属工艺 | 32篇 |
机械仪表 | 134篇 |
建筑科学 | 79篇 |
矿业工程 | 7篇 |
能源动力 | 13篇 |
轻工业 | 5篇 |
水利工程 | 4篇 |
石油天然气 | 16篇 |
武器工业 | 10篇 |
无线电 | 13篇 |
一般工业技术 | 36篇 |
冶金工业 | 16篇 |
原子能技术 | 154篇 |
自动化技术 | 193篇 |
出版年
2023年 | 10篇 |
2022年 | 9篇 |
2021年 | 15篇 |
2020年 | 29篇 |
2019年 | 16篇 |
2018年 | 18篇 |
2017年 | 33篇 |
2016年 | 36篇 |
2015年 | 35篇 |
2014年 | 45篇 |
2013年 | 76篇 |
2012年 | 40篇 |
2011年 | 41篇 |
2010年 | 36篇 |
2009年 | 43篇 |
2008年 | 21篇 |
2007年 | 34篇 |
2006年 | 53篇 |
2005年 | 36篇 |
2004年 | 25篇 |
2003年 | 19篇 |
2002年 | 16篇 |
2001年 | 9篇 |
2000年 | 9篇 |
1999年 | 11篇 |
1998年 | 13篇 |
1997年 | 10篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1959年 | 4篇 |
排序方式: 共有778条查询结果,搜索用时 24 毫秒
1.
Kazufumi Nagashima Lembit Sihver Nakahiro Yasuda 《Journal of Nuclear Science and Technology》2019,56(7):629-638
This paper aims at clarifying the potential and the limit of the method to surmise the timing of the containment vessel (CV) failure utilizing the Emergency Action Levels (EALs) issued as a nuclear operator’s notification in an early phase of the severe accident (SA). We analyzed the timings of the EALs issued in all kinds of the SA sequences of several PWR plant models by using the SA analysis code, MAAP. We found high correlations between the timing of SE41 (EAL issued at CV pressure of 0.5 design pressure) and the timing of the CV failure in the typical scenarios, e.g. over-pressure failures. We could therefore establish an evaluating method to estimate the time for a CV failure. This method has the potential to support the decision-making in nuclear emergency preparedness. 相似文献
2.
A number of worms, named P2P (peer-to-peer) passive worms, have recently surfaced, which propagate in P2P file-sharing networks and have posed heavy threats to these networks. In contrast to the majority of Internet worms, it is by exploiting users’ legitimate activities instead of vulnerabilities of networks in which P2P passive worms propagate. This feature evidently slows down their propagation, which results in them not attracting an adequate amount of attention in literature. Meanwhile, this feature visibly increases the difficulty of detecting them, which makes it very possible for them to become epidemic. In this paper, we propose an analytical model for P2P passive worm propagation by adopting epidemiological approaches so as to identify their behaviors and predict the tendency of their propagation accurately. Compared with a few existing models, dynamic characteristics of P2P networks are taken into account. Based on this proposed model, the sufficient condition for the global stability of the worm free equilibrium is derived by applying epidemiological theories. Large scale simulation experiments have validated both the proposed model and the condition. 相似文献
3.
ABSTRACT Governing the rate of heat transport by condenser tubes in the passive containment cooling system (PCCS), the steam condensation over a vertical cylinder in the presence of air was investigated experimentally. The main objective of this study was to explore if the condensation heat transfer coefficient relies on the tube dimension, which has been a variable missed in most condensation models or has been embraced without experimental demonstration under phase change environments. The mean heat transfer coefficient was measured in the condensation test facility named JERICHO (JNU Experimental Rig for Investigation of Condensation Heat transfer On tube). The outer diameter of the condenser tube used in this study was set to 21.5 mm. The measured heat transfer coefficients were compared to those obtained from the 40-mm-O.D. tube, and a multiplier to correct the variation of the heat transfer coefficient with the tube diameter was proposed for its application to Lee correlation. The proposed correlation was further validated against another set of experimental data obtained from a separate test facility housing the 31.8-mm-O.D. tube. 相似文献
4.
对AP1000压水堆核电站安全壳贯穿件的非径向管板焊接接头结构特点进行了介绍,并分析其超声检测工艺的重点和难点。通过建立统一的缺陷定位坐标系并结合被检构件的几何特点进行综合分析,推导得出了h值(缺陷回波最高点距套管外壁的距离)的计算方法。为超声检测对这类焊接接头缺陷的准确识别和定位提供了行之有效的方法,为解决这类焊接接头的超声检测技术受限区提供了行之有效的措施。 相似文献
5.
Majid Mazouchi Mohammad Bagher Naghibi‐Sistani Seyed Kamal Hosseini Sani Farzaneh Tatari Hamidreza Modares 《International Journal of Adaptive Control and Signal Processing》2019,33(2):262-284
This paper develops a relative output‐feedback–based solution to the containment control of linear heterogeneous multiagent systems. A distributed optimal control protocol is presented for the followers to not only assure that their outputs fall into the convex hull of the leaders' output but also optimizes their transient performance. The proposed optimal solution is composed of a feedback part, depending of the followers' state, and a feed‐forward part, depending on the convex hull of the leaders' state. To comply with most real‐world applications, the feedback and feed‐forward states are assumed to be unavailable and are estimated using two distributed observers. That is, a distributed observer is designed to measure each agent's states using only its relative output measurements and the information that it receives by its neighbors. Another adaptive distributed observer is designed, which uses exchange of information between followers over a communication network to estimate the convex hull of the leaders' state. The proposed observer relaxes the restrictive requirement of having access to the complete knowledge of the leaders' dynamics by all the followers. An off‐policy reinforcement learning algorithm on an actor‐critic structure is next developed to solve the optimal containment control problem online, using relative output measurements and without requiring the leaders' dynamics. Finally, the theoretical results are verified by numerical simulations. 相似文献
6.
为构建疏水性安全壳内壁面涂层以提高事故中的传热能力,以Si作为功能涂层材料,在其表面上制备了不同圆孔间距及圆孔深度的微孔阵列样品以研究微米结构对表面疏水特性的影响,并对其疏水机理进行分析。结果表明,所制备的微孔样品润湿特性均符合Cassie-Baxter模型,在本征接触角为69.5°的Si表面通过微孔结构调控可显著提高疏水特性,获得了具有140°接触角的优异疏水特性样品而未进行表面化学修饰。研究结果为设计安全壳涂层材料及其表面微结构提供了技术方案,为强化核电站非能动安全壳冷却系统传热性能提供了解决思路。 相似文献
7.
地下水封石油洞库建设具有投资大、无成熟设计施工规范、不确定因素多等特点,建设过程中存在着一定安全风险,开展地下水封石油洞库施工期安全风险评估研究具有重要意义。针对地下水封石油洞库施工期安全风险,从洞库稳定性与水封性两个方面,开展了洞库施工期安全风险评估研究,结合中国首座大型地下水封石油洞库工程对研究结论进行了验证。研究中,开展了地下水封石油洞库风险因子识别,进行了风险因子重要性和引发功能失效概率调查;采用模糊数学方法获得了风险因子模糊权重集和模糊评价集,得到了风险因子影响程度排序;总结了某地下水封石油洞库建设中典型稳定性和水封性风险事故,分析了事故发生原因,并与上文所得风险因子影响程度进行了对比验证。研究结果不但为提高地下水封石油洞库风险管理水平提供支撑,而且还可丰富地下工程安全风险评估研究内容。 相似文献
8.
Kevin M. P. van Eeten Dennis H. J. Hülsman John van der Schaaf Jaap C. Schouten 《American Institute of Chemical Engineers》2015,61(11):3656-3665
A novel type of rotor‐stator spinning disk device is proposed which allows for the entrapment of solid particles solely by hydrodynamic means. In this new configuration, the solid rotating disk is replaced with two conjoined rotors with a variable gap spacing. Liquid is fed through the top stator and can flow out again through the rotor‐rotor interior and the hollow rotation axis. Moreover, the volume between the two rotors is optionally filled with a highly porous reticulated carbon foam. It was found that particle containment was strongly improved by the presence of this reticulated foam as it hinders the buildup of centripetal boundary layer flow near the disks in the interior of the rotor‐rotor assembly. These centripetal boundary layers drag along particles resulting in a loss of containment. Experiments utilizing glass beads showed that particles with a diameter down to 17.8 µm can be completely entrapped when a carbon foam is placed between the two conjoined disks at rotor speeds up to the maximum investigated value of 178 rad s?1. Additionally, the rotor‐rotor gap did not have an effect on the particle entrapment level when the reticulated carbon foam was omitted and can be ascribed to the build‐up of boundary layers, which is independent of rotor‐rotor distance. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3656–3665, 2015 相似文献
9.
安全壳压力响应分析是验证非能动安全壳冷却系统(PCS)设计的重要内容,需考虑PCS的传热传质等各种现象的影响。本文应用DAKOTA程序耦合WGOTHIC程序对大型先进压水堆非能动安全壳压力响应进行敏感性分析,通过偏相关系数,定量评价了重要现象识别和排序表(PIRT)中各种现象对安全壳压力的影响程度。研究结果表明:质能释放现象、安全壳内初始环境条件、冷凝/蒸发现象显著影响安全壳压力。该研究结果为安全壳设计、安全分析和安全审评提供技术支持。 相似文献
10.