全文获取类型
收费全文 | 4556篇 |
免费 | 769篇 |
国内免费 | 275篇 |
专业分类
电工技术 | 145篇 |
综合类 | 486篇 |
化学工业 | 201篇 |
金属工艺 | 154篇 |
机械仪表 | 294篇 |
建筑科学 | 326篇 |
矿业工程 | 68篇 |
能源动力 | 66篇 |
轻工业 | 26篇 |
水利工程 | 244篇 |
石油天然气 | 163篇 |
武器工业 | 532篇 |
无线电 | 566篇 |
一般工业技术 | 853篇 |
冶金工业 | 99篇 |
原子能技术 | 30篇 |
自动化技术 | 1347篇 |
出版年
2024年 | 41篇 |
2023年 | 136篇 |
2022年 | 178篇 |
2021年 | 160篇 |
2020年 | 191篇 |
2019年 | 168篇 |
2018年 | 167篇 |
2017年 | 197篇 |
2016年 | 240篇 |
2015年 | 208篇 |
2014年 | 339篇 |
2013年 | 360篇 |
2012年 | 392篇 |
2011年 | 408篇 |
2010年 | 298篇 |
2009年 | 251篇 |
2008年 | 234篇 |
2007年 | 277篇 |
2006年 | 244篇 |
2005年 | 184篇 |
2004年 | 145篇 |
2003年 | 129篇 |
2002年 | 120篇 |
2001年 | 84篇 |
2000年 | 84篇 |
1999年 | 58篇 |
1998年 | 42篇 |
1997年 | 21篇 |
1996年 | 44篇 |
1995年 | 23篇 |
1994年 | 13篇 |
1993年 | 20篇 |
1992年 | 17篇 |
1991年 | 9篇 |
1990年 | 17篇 |
1989年 | 11篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1986年 | 9篇 |
1985年 | 11篇 |
1984年 | 6篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1976年 | 3篇 |
1965年 | 2篇 |
1958年 | 2篇 |
排序方式: 共有5600条查询结果,搜索用时 31 毫秒
81.
针对水下无人航行器UUV(Unmanned Underwater Vehicle)的导航测速数据受海洋环境噪声影响大、处理实时性要求高的问题,提出了一种基于灰色动态预测和数据自适应融合的滤波方法。该方法考虑到UUV的速度在连续变化前提下可能存在的机动性,将基本的静态灰色预测模型改进为灰色动态预测模型,以获得速度数据的近似估计值。然后根据估计值和实际采样值之间的偏差,自适应的调整两者之间的权重系数进行融合,以实现实时的数据滤波。通过对UUV海上试验数据的验证,证明了该方法的有效性。 相似文献
82.
This paper presents a novel integrated guidance and control strategy for docking of autonomous underwater vehicles. The approach to the base, and hence the control design, is divided in two steps: (i) in the first, at higher speed, the vehicle dynamics is assumed to be underactuated, and an appropriate control law is derived to steer the vehicle towards the final docking path, achieving convergence to zero of the appropriate error variables for almost all initial conditions; (ii) in the second stage, at low speed, the vehicle is assumed to be fully actuated, and a robust control law is designed that achieves convergence to zero of the appropriate error variables for all initial conditions, in the presence of parametric model uncertainty. Simulations are presented illustrating the performance of the proposed controllers, including model uncertainty and sensor noise. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
83.
Improved Quality Output through Computer‐Based Training: An Automotive Assembly Field Study
下载免费PDF全文
![点击此处可从《人机工程学与制造业中的人性因素》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In this article, two field experiments, conducted in an automotive assembly plant, evaluate how computer‐based training of operational sequences and related quality information can support the assembly performance of the operators. The experiments were performed during the launch of a new vehicle. A comparison was made of learning progress and quality performance between a reference group of operators that only had regular training and a test group for which some of the regular training was replaced with individual computer‐based training. Both quantitative measures of the quality output and questionnaires and observations were used to evaluate the effects of computer‐based training. The results show a clear positive difference in learning progress and improvements in quality output for the test group compared with the reference group. This combined with positive attitudes expressed by the operators and their team leaders shows that this type of training is an effective way to train operators during launches of new vehicles in automotive production. 相似文献
84.
85.
针对联合作战指挥控制系统功能组成和特点,分析并构造了指挥控制系统的效能评估指标体系。探讨了效能评估的主要方法,根据联合作战的特点,采用了作战模拟法,设计并实现了指挥控制系统效能评估试验框架。 相似文献
86.
《Information Security Journal: A Global Perspective》2013,22(1):40-46
ABSTRACT Social engineering is a methodology that allows an attacker to bypass technical controls by attacking the human element in an organization. There are many techniques commonly used in social engineering including but not limited to Trojan and phishing email messages, impersonation, persuasion, bribery, shoulder surfing, and dumpster diving. Hackers rely on social engineering attacks to bypass technical controls by focusing on the human factors. Social engineers often exploit the natural tendency people have toward trusting others who seem likeable or credible, deferring to authority or need to acquiesce to social conformity. Mitigation of social engineering begins with good policy and awareness training, but there are a number of other approaches an organization can take to defend against this type of an attack. Social engineering attacks are likely to increase, and it is becoming increasingly important for organizations to address this issue. 相似文献
87.
《Information Security Journal: A Global Perspective》2013,22(4):183-192
ABSTRACT Insider threats pose significant challenges to any organization. Many solutions have been proposed in the past to detect insider threats. Unfortunately, given the complexity of the problem and the human factors involved, many solutions which have been proposed face strict constraints and limitations when it comes to the working environment. As a result, many past insider threat solutions have in practice failed in their implementations. In this work, we review some of the recent insider threat detection solutions and explore their benefits and limitations. We also discuss insider threat issues for emerging areas such as cloud computing, virtualization, and social networking. 相似文献
88.
89.
This study compared the mounting time and strain on the head‐neck while using an old model (forehead and cheek supported) and a new model (head harness supported) of head‐mounted night vision goggle systems in the postures of standing, sitting, and lying prone. The results showed that effectively reducing the mounting time was attributed to the ease and less time required for length adjustments of the head harness in the new model. The novel device received higher positive subjective ratings for convenience and comfort while wearing than did the old model. Although the weight of the new model was decreased to 0.794 kg and the length was reduced to 0.155 m, the loads on the head‐neck complex remained high. These findings suggest that a rifle should be fitted with the night vision goggle or handheld model to decrease neck‐shoulder workload if the prone position is the most frequent and important posture for soldiers. © 2011 Wiley Periodicals, Inc. 相似文献
90.
Underwater communication primarily utilizes propagation of acoustic waves in water. Its unique characteristics, including slow propagation speed and low data rates, pose many challenges to Media Access Control (MAC) protocol design. In most existing handshaking-based underwater MAC protocols, only an initiating sender can transmit data packets to its intended receiver after a channel reservation through a Request-to-Send (RTS)/Clear-to-Send (CTS) handshake. This conventional single-node transmission approach is particularly inefficient in underwater environments, as it does not account for long propagation delays. To improve channel utilization in high latency environments, we propose a novel approach that exploits the idle waiting time during a 2-way handshake to set up concurrent transmissions from multiple nodes. The sender can coordinate multiple first-hop neighbors (appenders) to use the current handshake opportunity to transmit (append) their data packets with partially overlapping transmission times. After the sender finishes transmitting its packets to its own receiver, it starts to receive incoming appended packets that arrive in a collision-free packet train. This not only reduces the amount of time spent on control signaling, but it also greatly improves packet exchange efficiency. Based on this idea, we propose an asynchronous, single-channel handshaking-based MAC protocol based on reverse opportunistic packet appending (ROPA). From extensive simulations (single- and multi-hop networks) and comparisons with several existing MAC protocols, including MACA-U, MACA-UPT, BiC-MAC, Slotted-FAMA, DACAP, unslotted Aloha, we show that ROPA significantly increases channel utilization and offers performance gains in throughput and delay while attaining a stable saturation throughput. 相似文献