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   649篇
  免费   70篇
  国内免费   32篇
电工技术   12篇
综合类   41篇
化学工业   32篇
金属工艺   11篇
机械仪表   41篇
建筑科学   6篇
能源动力   1篇
轻工业   17篇
武器工业   2篇
无线电   77篇
一般工业技术   83篇
冶金工业   258篇
原子能技术   3篇
自动化技术   167篇
  2023年   7篇
  2022年   7篇
  2021年   17篇
  2020年   10篇
  2019年   10篇
  2018年   11篇
  2017年   22篇
  2016年   21篇
  2015年   15篇
  2014年   26篇
  2013年   27篇
  2012年   32篇
  2011年   56篇
  2010年   40篇
  2009年   43篇
  2008年   74篇
  2007年   43篇
  2006年   40篇
  2005年   42篇
  2004年   55篇
  2003年   34篇
  2002年   33篇
  2001年   20篇
  2000年   10篇
  1999年   3篇
  1998年   2篇
  1997年   5篇
  1996年   3篇
  1994年   2篇
  1993年   2篇
  1992年   3篇
  1991年   1篇
  1988年   1篇
  1987年   1篇
  1985年   1篇
  1984年   3篇
  1979年   1篇
  1968年   1篇
  1967年   2篇
  1966年   2篇
  1965年   3篇
  1964年   3篇
  1963年   5篇
  1962年   1篇
  1961年   1篇
  1960年   1篇
  1959年   2篇
  1957年   1篇
  1956年   2篇
  1954年   2篇
排序方式: 共有751条查询结果,搜索用时 46 毫秒
1.
目的 介绍国内外智能假肢膝关节研究的主要进展,为相关领域的研发提供可借鉴的思路.方法 基于机械结构、调控方式、驱动方式,对典型假肢膝关节进行了分类比较,并从假肢穿戴者的运动意图识别、驱动控制、人机协调控制等方面做了分析.此外,对假肢膝关节在智能化研究与安全性、个性化与通用性、人机共融技术、科学伦理、关键技术等方面需要注意的问题,提出了研发要点和技术思路.结论 智能假肢膝关节应注重安全性与稳定性,规避用户在使用过程中的潜在危险因素;实现假肢控制参数的自整定和灵活适配,在个性化与通用性上达到平衡;综合考虑人—机—环境因素,实现协调控制;坚持"以人为本",在技术方法和科学伦理两个方面开展医工结合的研究;突破关键技术限制,建立完善的社会医疗康复保障服务体系.  相似文献   
2.
摘要:对腿部运动意图识别算法的实时性能进行综合可靠的评价是实现下肢假肢灵活稳定控制的前提。提出一种逐层分级的基于下肢运动意图识别算法的实时测评方法,对算法的可靠性、稳定性以及运动意图识别速度进行综合评价。利用开发的运动意图识别算法评测系统,对基于肌电信号源和机械信号源的两种运动意图识别算法进行了实时性能测试,发现肌电信号源的算法识别时间大于机械信号源算法,但是其算法稳定性优于机械信号源算法。进一步地,还利用该评测系统有效地区分出正常识别策略与异常识别策略,发现正常策略的动作识别稳定系数比异常策略高25%左右。因此,所提的基于下肢运动意图识别算法的实时测评方法,能够对不同信号源算法以及不同识别策略的实时性能进行有效评价,为智能下肢假肢控制系统开发提供可供参考的测试平台。 .txt  相似文献   
3.
Background: Animal and clinical studies have demonstrated that the loudness dependence of auditory evoked potentials (LDAEP) is inversely related to central serotonergic activity, with a high LDAEP reflecting weak serotonergic neurotransmission and vice versa, though the findings in humans have been less consistent. In addition, a high pretreatment LDAEP appears to predict a favorable response to antidepressant treatments that augment the actions of serotonin. The aim of this study was to test whether the baseline LDAEP is correlated with response to long-term maintenance treatment in patients with major depressive disorder (MDD). Methods: Scalp N1, P2 and N1/P2 LDAEP and standardized low resolution brain electromagnetic tomography-localized N1, P2, and N1/P2 LDAEP were evaluated in 41 MDD patients before and after they received antidepressant treatment (escitalopram (n = 32, 10.0 ± 4.0 mg/day), sertraline (n = 7, 78.6 ± 26.7 mg/day), and paroxetine controlled-release formulation (n = 2, 18.8 ± 8.8 mg/day)) for more than 12 weeks. A treatment response was defined as a reduction in the Beck Depression Inventory (BDI) score of >50% between baseline and follow-up. Results: The responders had higher baseline scalp P2 and N1/P2 LDAEP than nonresponders (p = 0.017; p = 0.036). In addition, changes in total BDI score between baseline and follow-up were larger in subjects with a high baseline N1/P2 LDAEP than those with a low baseline N1/P2 LDAEP (p = 0.009). There were significantly more responders in the high-LDAEP group than in the low-LDAEP group (p = 0.041). Conclusions: The findings of this study reveal that a high baseline LDAEP is associated with a clinical response to long-term antidepressant treatment.  相似文献   
4.
为治疗肛门失禁问题,设计一种基于弹性缩放原理的新型人工肛门括约肌系统。弹性缩放式假体内壁嵌入超薄(0.208mm)生物压力传感器,感知假体开合程度,在体内控制单元的控制下,实现对肠道的精准咬合与释放;在假体闭合状态下,假体内嵌传感器实时感知肠道压力变化,根据此压力参数,系统智能识别便意并实现排便预警。括约肌系统设置体外便捷式遥控端,方便患者自主选择排便时间;系统采用经皮能量传输方式实现安全供能。开展了针对假体的力学实验,与血供安全力学分析,保证假体的缩放功能符合临床应用要求。进行3次离体实验,其结果验证了系统的控便稳定性并初步取得便意阈值。  相似文献   
5.
城市滨水空间恢复性评价的视听影响因素研究   总被引:2,自引:0,他引:2  
具有恢复性的城市环境可以减缓心理疲劳、促进生理健康。以天津市海河沿岸滨水空间为例,通过调查问卷探讨了不同人工化程度的城市滨水空间的恢复性评价、视听觉环境感知对恢复性评价的影响以及滨水空间中具有潜在恢复性的视听觉要素。结果表明:人工化程度较高的滨水空间其恢复性评价较低,但通过适当视听觉设计可提高其恢复性;滨水空间恢复性评价随视听觉环境评价的提高而提高,其中视觉环境更重要;最具有恢复性和滨水特点的视觉要素是水鸟、亲水平台等,听觉要素是蛙鸣声、水流声等,适度添加这些元素可以提高城市滨水空间的恢复性评价。  相似文献   
6.
In recent years, the use of hip prostheses has become a routine procedure. The use of total hip replacement has evolved in recent years to a routine procedure. Despite this experience, it always comes back to complications. Especially the migration or loosening of the acetabular component because of the artificial load adaptive bone remodeling is still a current problem. This is due to the changing mechanical situation after the implantation of the prosthesis. Another problem is the high bone loss during implantation, which complicates a revision of the prosthesis. One solution is the use of patient‐specific prostheses. So far, the use of these prostheses is limited due to the time‐consuming and cost‐intensive production. The overall objective of the presented project in this publication is the development and establishment of an innovative concept for the production of patient‐specific hip prosthesis made of titanium plates by sheet metal forming. The idea of this concept involves the development of a two‐stage process. First of all a standardized hip prosthesis is made by high‐pressure sheet metal forming and then individually in the second step. This publication contains the derivation of the standard prosthesis. For this purpose, a design methodology was generated, based on the so‐called agglomerative clustering. In addition, presents the results of the numerical preliminary design of the first stage of the process and the tool developed concept in the course of this paper.  相似文献   
7.
张平  冯海泓  胡晓城 《声学技术》2015,34(6):529-534
扬声器异常音作为产品音质好坏的一种具体表现形式,其检测问题也属于音质评价的一方面。故本文借鉴国际电信联盟推荐的音频质量感知评价算法PEAQ(Perceptual Evaluation of Audio Quality)的实现原理,将其中的人耳听觉模型应用在扬声器的异常音检测中。取标准扬声器样品的声信号作为参考信号,待测扬声器的声信号作为待测信号,两个信号通过人耳听觉模型逐帧处理后,计算得到信号感知差异曲线,用以区分异常音样品。人耳听觉模型包括了中外耳频率加权、听觉滤波器分组、添加内部噪声以及掩蔽效应模拟。将本文所述方法与人工听音以及国际通用的高阶谐波检测扬声器异常音的方法做了比较,实验室检测结果验证了该方法的可行性。  相似文献   
8.
A variable-dimensional vector modulation (VDVM) scheme is introduced to maximize the efficiency of the norm-space DWT-based blind audio watermarking technique. This flexible scheme allows the watermarking algorithm to reach a balance between robustness and capacity, while the imperceptivity is always ensured. The imperfection of applying quantization index modulation in the open-loop case has been rectified. The effectiveness of the proposed scheme is proven using the perceptual evaluation of audio quality (PEAQ) and bit error rates of recovered watermarks under various signal processing attacks. Experimental results show that the proposed VDVM scheme is comparable to other recently developed methods in robustness and imperceptivity even at a capacity as high as 301.46 bps. Such a capacity can be further doubled by halving the dimension of the involved DWT vector, while the robustness is still maintained at a satisfactory level.  相似文献   
9.
《Ergonomics》2012,55(4):328-344
The measurement of the work-load in industry necessitates the use of reliable methods and of apparatus which is both robust and foolproof. Three methods are usually employed at our Institute: (1) an exact time-study covering the whole working day and including details of all accessory operations and all rest pauses; (2) the measurement of energy cost of work by the use of the respirometer developed at the Institute; (3) the measurement of pulse rate by means of the Muller pulse counter.

A number of examples are quoted of the use of these methods in several forging shops and in a motor car factory. The examples include instances of underloading and overloading of the worker, and the reasons and remedies are discussed.  相似文献   
10.
Helmets provide soldiers with ballistic and fragmentation protection but impair auditory spatial processing. Missed auditory information can be fatal for a soldier; therefore, helmet design requires compromise between protection and optimal acoustics. Twelve soldiers localised two sound signals presented from six azimuth angles and three levels of elevation presented at two intensity levels and with three background noises. Each participant completed the task while wearing no helmet and with two U.S. Army infantry helmets – the Personnel Armor System for Ground Troops (PASGT) helmet and the Advanced Combat Helmet (ACH). Results showed a significant effect of helmet type on the size of both azimuth and elevation error. The effects of level, background noise, azimuth and elevation were found to be significant. There was no effect of sound signal type. As hypothesised, localisation accuracy was greatest when soldiers did not wear helmet, followed by the ACH. Performance was worst with the PASGT helmet.  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