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   591篇
  免费   11篇
  国内免费   14篇
电工技术   15篇
综合类   18篇
化学工业   31篇
金属工艺   15篇
机械仪表   88篇
建筑科学   19篇
矿业工程   5篇
能源动力   22篇
轻工业   10篇
水利工程   3篇
石油天然气   5篇
武器工业   1篇
无线电   38篇
一般工业技术   79篇
冶金工业   84篇
原子能技术   25篇
自动化技术   158篇
  2024年   2篇
  2023年   3篇
  2022年   7篇
  2021年   16篇
  2020年   8篇
  2019年   11篇
  2018年   7篇
  2017年   9篇
  2016年   25篇
  2015年   14篇
  2014年   28篇
  2013年   35篇
  2012年   43篇
  2011年   42篇
  2010年   31篇
  2009年   29篇
  2008年   30篇
  2007年   32篇
  2006年   32篇
  2005年   29篇
  2004年   24篇
  2003年   20篇
  2002年   16篇
  2001年   7篇
  2000年   7篇
  1999年   16篇
  1998年   4篇
  1997年   9篇
  1996年   11篇
  1995年   9篇
  1994年   7篇
  1993年   4篇
  1992年   7篇
  1991年   3篇
  1990年   3篇
  1989年   6篇
  1988年   2篇
  1987年   5篇
  1986年   3篇
  1985年   1篇
  1983年   2篇
  1981年   1篇
  1980年   3篇
  1979年   1篇
  1978年   3篇
  1977年   3篇
  1976年   2篇
  1975年   1篇
  1973年   2篇
  1972年   1篇
排序方式: 共有616条查询结果,搜索用时 15 毫秒
81.
Thermal spray process is a technique of coating manufacturing implementing a wide variety of materials and processes. This technique is characterized by up to 150 processing parameters influencing the coating properties. The control of the coating quality is needed through the consideration of a robust methodology that takes into account the parameter interdependencies, the process variability and offers the ability to quantify the processing parameter-process response relationships. The aim of this work is to introduce a new approach based on artificial intelligence responding to these requirements. A detailed procedure is presented considering an artificial neural network (ANN) structure which encodes implicitly the physical phenomena governing the process. The implementation of such a structure was coupled to experimental results of an optic sensor controlling the powder particle fusion state before the coating formation. The optimization steps were discussed and the predicted results were compared to the experimental ones allowing the identification of the control factors.  相似文献   
82.
使用表达式分析的通用故障诊断系统设计与实现   总被引:1,自引:0,他引:1  
基于知识的故障诊断专家系统在应用时面临知识获取、知识表达和知识与诊断推理有机融合等几方面的困难。本文论述了一种使用表达式解析的故障诊断方法,并将其用于某型雷达系统的故障诊断保障系统中。该方法将知识表示为逻辑表达式,推理机使用表达式解析的方法推理知识。使用该方法,知识的获取和更新更加方便,并且推理机和表达式相互独立,具有相当的通用性。  相似文献   
83.
牙鲆淋巴囊肿病的PCR诊断方法研究   总被引:14,自引:0,他引:14  
以中国养殖牙鲆 (Paralichthysolivaceus)淋巴囊肿病毒 (Lymphocystisdiseasevirus,LCDVcn)主要衣壳蛋白 (majorcapsidprotein ,MCP)基因的中间保守序列为目标基因 ,设计了一对特异性引物。该引物可扩增出 172bp的病毒DNA片段 ,其最小DNA检出量为 0 0 183ng。用PCR法从人工感染淋巴囊肿病毒 3天的牙鲆血、鳃、肝、脾、肠、胃及自然发病牙鲆的肿瘤中 ,分别检测到了LCDV的存在。本实验结果证明 ,PCR法对于早期检测LCDV是十分有效的。  相似文献   
84.
The accident scenarios of a nuclear power plant are composed of an initiating event (IE), additional events/failures and human inappropriate actions, the combinations of which lead to irreversible consequences. In such a dynamic situation, operators should diagnose the occurring events/failures (including an initiating event and additional events) and assess the related situations utilising the available resources such as operating procedures or human–machine systems to control and maintain the plant in a stable condition. The misdiagnosis or diagnosis failure of the occurring events could cause critical human inappropriate actions that aggravate the plant condition, which is termed as errors of commission (EOCs). This paper presents a methodology for analysing the potential for diagnosis failure of the initiating and additional events and the consequent EOC events, based on the operating procedures, in the accident scenarios of nuclear power plants. The method to be presented categorizes the diagnostic situations in the accident scenarios into three cases according to the structure of the emergency operating procedures (EOPs) and the time of the occurring events: (1) the diagnosis of an initiating event, (2) the diagnosis of both an initiating event and an additional event when an additional event occurs prior to the performance of the diagnosis procedure, and (3) the diagnosis of an additional event when an additional events occurs after the performance of the diagnosis procedure. The application of the method is illustrated through three case example scenarios: (1) the power-operated relief valve (PORV) or the pressurizer safety valve (PSV) LOCA, (2) the loss of all feedwater (LOAF) event (loss of main feedwater*loss of auxiliary feedwater), (3) the sequence of<the station blackout (SBO)*loss of turbine-driven (or diesel-driven) auxiliary feedwater*PSV stuck-open*recovery of AC power>.  相似文献   
85.
Certain types of non-linear transformations of stochastic signal processes have proven useful in engineering applications. A form of processing called hard clipping (or hard limiting) has frequently been used in electronic systems which work in “real time” in order to reduce the number of information bits which the system has to process. With hard clipping only one binary digit is used per sample value of an input signal X(t). However, information is lost about X(t) and the spectrum which is calculated from the clipped signal is a distorted form of the original signal spectrum. By a sine transformation of the sample covariance of the clipped process, a consistent estimator is derived for the spectral density of X(t). The asymptotic variance-covariance function is calculated for this estimator.  相似文献   
86.
This paper presents a technique denoted as sub sample size bounding (SSSB) useable for the statistical derivation of context-specific probabilities from data available in existing reports on operating experience. Applications for human reliability analysis (HRA) are emphasized in the presentation of the technique. Exemplified by a sample of 180 abnormal event sequences, it is outlined how SSSB can provide viable input for the quantification of errors of commission (EOCs).  相似文献   
87.
In this paper, basic unsteady flow types and transient event types are categorized, and then unsteady friction models are tested for each type of transient event. One important feature of any unsteady friction model is its ability to correctly model frictional dissipation in unsteady flow conditions under a wide a range of possible transient event types. This is of importance to the simulation of transients in pipe networks or pipelines with various devices in which a complex series of unsteady flow types are common. Two common one-dimensional unsteady friction models are considered, namely, the constant coefficient instantaneous acceleration-based model and the convolution-based model. The modified instantaneous acceleration-based model, although an improvement, is shown to fail for certain transient event types. Additionally, numerical errors arising from the approximate implementation of the instantaneous acceleration-based model are determined, suggesting some previous good fits with experimental data are due to numerical error rather than the unsteady friction model. The convolution-based model is successful for all transient event types. Both approaches are tested against experimental data from a laboratory pipeline.  相似文献   
88.
目的:探讨18F-FDGPETCT显像在难确诊性鼻咽癌中的临床应用价值.方法:回顾性分析2020年3月-2021年2月我院临床高度怀疑鼻咽癌的60例患者,首次或多次行鼻咽镜病理活检阴性,行常规18F-FDGPET/CT检查,根据PET/CT结果引导再次行鼻咽镜病理活检.将上述患者分为两组,以最终病理结果为金标准,分为阳...  相似文献   
89.
This study assessed the possible differences in the classification of adolescent gamblers when using the South Oaks Gambling Screen-Revised for Adolescents (SOGS-RA; K. C. Winters, R. D. Stinchfield, & J. Fulkerson, 1993) versus a clinical interview that was based on Diagnostic and Statistical Manual of Mental Disorders (DSM-IV; American Psychiatric Association, 1994) criteria for pathological gambling. A total of 631 adolescents ages 15-17 years participated in the two phases of the study. Results revealed that of the 93 adolescents who had been screened as problem gamblers according to the SOGS-RA, only 7 could be clinically confirmed as pathological gamblers according to the criteria used at present to define pathological gambling. The need to clarify the construct of pathological gambling among youth is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
90.
Early starting, lifetime criminal persistence has been called sociopathy, antisocial personality disorder, and psychopathy. There is, however, disagreement about its core features and which measure is best for identifying such individuals. In the 1st of 2 studies of male offenders (n = 74), we found a large association between scores on the Psychopathy Checklist-Revised (PCL-R; R. D. Hare, 1991) and the Diagnostic and Statistical Manual of Mental Disorders (4th ed. [DSM-IV; American Psychiatric Association, 1994) antisocial personality disorder criteria scored as a scale. The second study (n = 684) replicated this finding and found that, as previously shown for PCL-R scores, a discrete class (or taxon) also underlies scores on items reflecting antisocial personality disorder. The high association among these sets of items and their similarity in predicting violence suggested that the same natural class underlies each. Results indicated that life-course-persistent antisociality can be assessed well by measures of psychopathy and antisocial personality disorder. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  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