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   3136篇
  免费   124篇
  国内免费   1篇
电工技术   12篇
化学工业   755篇
金属工艺   25篇
机械仪表   53篇
建筑科学   118篇
矿业工程   8篇
能源动力   45篇
轻工业   578篇
水利工程   40篇
石油天然气   8篇
无线电   93篇
一般工业技术   282篇
冶金工业   936篇
原子能技术   3篇
自动化技术   305篇
  2023年   21篇
  2022年   90篇
  2021年   84篇
  2020年   65篇
  2019年   50篇
  2018年   66篇
  2017年   63篇
  2016年   67篇
  2015年   66篇
  2014年   82篇
  2013年   219篇
  2012年   148篇
  2011年   175篇
  2010年   133篇
  2009年   150篇
  2008年   126篇
  2007年   142篇
  2006年   106篇
  2005年   116篇
  2004年   99篇
  2003年   91篇
  2002年   74篇
  2001年   54篇
  2000年   47篇
  1999年   41篇
  1998年   50篇
  1997年   45篇
  1996年   46篇
  1995年   41篇
  1994年   43篇
  1993年   38篇
  1992年   44篇
  1991年   13篇
  1990年   38篇
  1989年   48篇
  1988年   28篇
  1987年   47篇
  1986年   41篇
  1985年   39篇
  1984年   31篇
  1983年   19篇
  1982年   43篇
  1981年   22篇
  1980年   22篇
  1979年   14篇
  1978年   26篇
  1977年   16篇
  1976年   11篇
  1975年   16篇
  1974年   13篇
排序方式: 共有3261条查询结果,搜索用时 15 毫秒
11.
A structured in-depth interview employing standardized criteria was used to determine the prevalence of lifetime and current alcohol dependence (alcoholism) in unselected consecutive patients admitted to a regional Level I trauma center. Of 629 patients, 157 (25.0%) were current alcoholics at the time of injury. An additional 87 (13.8%) were diagnosed as lifetime non-current alcoholics. There was no significant difference in the rates of current alcohol dependence among patients injured in vehicular crashes (23.5%), other unintentional trauma victims (29.3%), and those injured as a result of violence (24.6%). Of BAC + (blood alcohol concentration positive) patients, 54.5% were current alcoholics. However, 14.4% of alcohol-negative patients were also diagnosed as alcohol dependent.  相似文献   
12.
The settling rates and adsorption isotherms produced by a variety of suites of cationic polyelectrolytes in 3% kaolin suspensions were measured. Settling rates increased with molar mass even for low-mass, high-charge polymers. The very high settling rates produced by cationic copolymers of acrylamide decreased as the charge density of the polymer used increased. Hydrolysis of unbuffered polymers occurred over time and produced large changes in the effectiveness of the polymers. This is attributed to conformational changes. © 1994 John Wiley & Sons, Inc.  相似文献   
13.
To determine if the sexually dimorphic area (SDA) of the gerbil hypothalamus affects male sexual behavior through its projections to the retrorubral field (RRF) or ventrolateral periaqueductal gray (PAGvl), these pathways were lesioned asymmetrically. Unilateral radio frequency lesions of the lateral SDA (LSDA), the major source of the pathways, impaired mating when combined with contralateral RRF, but not PAGvl, lesions. N-methyl-{d}-aspartate (NMDA) lesions of the medial SDA, LSDA, and the area between them (the total pathway source) eliminated mating when combined with contralateral, but not ipsilateral, NMDA lesions of the RRF. To determine if A8 cells contributed to these effects, males received NMDA in the SDA and NMDA or 6-hydroxydopamine in the contralateral RRF. When combined with large SDA lesions, A8 lesions impaired but did not eliminate mating. Thus the SDA–RRF pathway, but not an SDA-A8 pathway, is essential for sexual behavior in male gerbils. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
14.
Investigators have concluded that excessive numbers of errors in test administration and scoring are routinely committed by both graduate students and practicing psychologists. Developing new methods for teaching assessment is viewed as a major means of improving competency. Unlike previous studies, this investigation examined the impact of both lecture and laboratory interventions designed to improve graduate student performance in assessment. Interventions consisted of weekly lecture quizzes and a variety of laboratory interventions. The results suggest that the interventions used can significantly improve students' lecture and laboratory performance when compared with controls. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
15.
This study examines why people choose to self-disclose on "Donahue" and what role television plays in their lives prior to disclosure. Focused interviews were conducted with 29 informants between the ages of 12 and 68 who had appeared on the program. Analysis revealed that an evangelical fervor underpinned their decision, overshadowing other concerns about disclosure in a public forum. Informants generally reported low levels of television viewing. They held a pragmatic view of talk shows as avenues to reach a dual audience that included the mainstream public and members of their out-groups. Television disclosure is a tactic in a counterhegemonic struggle. Respondents utilized numerous impression management techniques in their efforts to manage their stigmatized status. Participants on "Donahue" risk co-optation, but running the gauntlet of criticism and ridicule allows an opportunity for delabeling rarely afforded to out-groups.  相似文献   
16.
Tension and vascular headache patients, initially treated with biofeedback and/or relaxation training in either a minimal therapist contact protocol (3 visits) or an intensive individual protocol (10 or 16 visits) were followed-up prospectively for 2 years. In the first study, for the first 6 months of follow-up, half of all patients continued to keep headache diaries and were seen monthly and the other half had only minimal contact. The results at 1-year follow-up, based on 4 weeks of daily headache diaries, revealed equally good maintenance from both treatment protocols and from both follow-up conditions. In Study 2, we found that patients remained improved over pretreatment baseline levels at the 2-year follow-up regardless of initial treatment intensity. Approximately three quarters of vascular patients who were initially improved at posttreatment remained improved at 2 years. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
17.
Examined intake profiles of 54 depressed women survivors of child sexual abuse presenting for a specialized group therapy program at a community mental health center. The 32 therapy completers were compared with the 22 dropouts. Both groups possessed extensive and severe childhood and adult abuse histories. Both were extremely socially disadvantaged and clinically impaired as measured on the Millon Clinical Multiaxial Inventory (MCMI). Dropouts were more likely to have been battered as children and to have been sexually abused only within the family. Completers were more likely to have been multiply offended both by intrafamilial and extrafamilial perpetrators. The groups differed in terms of marital status and extent of economic dependence on spouse. Dropouts appeared to be more actively enmeshed in the abuse cycle at the time of therapy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
18.
We describe a trainable system for analyzing videos of developing C. elegans embryos. The system automatically detects, segments, and locates cells and nuclei in microscopic images. The system was designed as the central component of a fully automated phenotyping system. The system contains three modules 1) a convolutional network trained to classify each pixel into five categories: cell wall, cytoplasm, nucleus membrane, nucleus, outside medium; 2) an energy-based model, which cleans up the output of the convolutional network by learning local consistency constraints that must be satisfied by label images; 3) a set of elastic models of the embryo at various stages of development that are matched to the label images.  相似文献   
19.
Objective: To pilot test a health promotion intervention for women with physical disabilities. Design: Pre- and postintervention questionnaires. Participants: Two groups of women with physical disabilities (n=15). Intervention: Seven-session weekly workshop intervention grounded primarily in social-cognitive theory. Setting: Disability and rehabilitation settings. Main Outcome Measures: Indicators of health status. Results: Statistically significant positive changes between pre- and postintervention scores on measures of self-efficacy for dietary behaviors, medical decision making, social interaction, physical functioning, impact of physical limitation on role activities, and vitality. Conclusion: Women with disabilities who participate in this health promotion intervention may exhibit improvements on indicators of health status. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
20.
This paper documents the first of the two interrelated studies that were conducted to more fundamentally understand the scalability of flame heat flux, the motivation being that it has been reported that flame heat flux back to the burning surface in bench‐scale experiments is not the same as for large‐scale fires. The key aspect was the use of real scale applied heat flux up to 200kW/m2 which is well beyond that typically considered in contemporary testing. The main conclusions are that decomposition kinetics needs to be included in the study of ignition and the energy balance for steady burning is too simplistic to represent the physics occurring. An unexpected non‐linear trend is observed in the typical plotting methods currently used in fire protection engineering for ignition and mass loss flux data for several materials tested and this non‐linearity is a true material response. Using measured temperature profiles in the condensed phase shows that viewing ignition as an inert material process is inaccurate at predicting the surface temperature at higher heat fluxes. The steady burning temperature profiles appear to be invariant with applied heat flux. This possible inaccuracy was investigated by obtaining the heat of gasification via the ‘typical technique’ using the mass loss flux data and comparing it to the commonly considered ‘fundamental’ value obtained from differential scanning calorimetry measurements. This comparison suggests that the ‘typical technique’ energy balance is too simplified to represent the physics occurring for any range of applied heat flux. Observed bubbling and melting phenomena provide a possible direction of study. Copyright © 2007 John Wiley & Sons, Ltd.  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