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   1259篇
  免费   22篇
  国内免费   1篇
电工技术   14篇
综合类   1篇
化学工业   154篇
金属工艺   8篇
机械仪表   15篇
建筑科学   49篇
矿业工程   2篇
能源动力   12篇
轻工业   112篇
水利工程   33篇
石油天然气   2篇
无线电   73篇
一般工业技术   154篇
冶金工业   483篇
原子能技术   5篇
自动化技术   165篇
  2023年   6篇
  2022年   7篇
  2021年   8篇
  2019年   17篇
  2018年   22篇
  2017年   16篇
  2016年   12篇
  2015年   16篇
  2014年   19篇
  2013年   47篇
  2012年   33篇
  2011年   54篇
  2010年   45篇
  2009年   44篇
  2008年   44篇
  2007年   66篇
  2006年   57篇
  2005年   42篇
  2004年   34篇
  2003年   33篇
  2002年   26篇
  2001年   25篇
  2000年   24篇
  1999年   30篇
  1998年   84篇
  1997年   68篇
  1996年   43篇
  1995年   36篇
  1994年   28篇
  1993年   35篇
  1992年   31篇
  1991年   14篇
  1990年   17篇
  1989年   15篇
  1988年   11篇
  1987年   9篇
  1986年   13篇
  1985年   12篇
  1984年   11篇
  1983年   13篇
  1982年   9篇
  1981年   8篇
  1980年   9篇
  1979年   8篇
  1978年   12篇
  1977年   13篇
  1976年   11篇
  1975年   8篇
  1973年   5篇
  1971年   5篇
排序方式: 共有1282条查询结果,搜索用时 15 毫秒
151.
This study of postmenopausal female smokers (N = 94) asked: During short-term smoking abstinence, do the beneficial effects of transdermal nicotine replacement therapy (NRT) on acute symptomatology (i.e., withdrawal, cigarette craving, smoking urges, mood, depressive symptoms, motor speed, and reaction time) differ in women who use and do not use hormone replacement therapy (HRT)? Participants were recruited according to HRT and non-HRT use (self-selecting), then randomized within strata to active nicotine or placebo nicotine patch. After 1 baseline week of smoking, participants quit smoking for 2 weeks. Women received cessation counseling and were monitored for abstinence. Dependent measures were collected during five clinic visits. Two-way analysis of covariance (ANCOVA) were run on change scores for dependent variables, with nicotine patch group (active/placebo) and HRT group (HRT/non-HRT) as independent variables and age as a covariate. No interactions were found between HRT and patch condition, but both showed specific effects. During the first abstinent week, women on active nicotine patch (compared with placebo) experienced less severe withdrawal, greater reductions in cigarette cravings, and lower (more favorable) Factor 1 scores on the Questionnaire of Smoking Urges. During the second abstinent week, women using HRT (compared with the non-HRT group) exhibited better mood (Profile of Mood States scores) and less depression (Beck Depression Inventory scores). These results suggest the following: First, the efficacy of transdermal nicotine replacement is not adversely modified by women's HRT use; second, ovarian hormones might influence women's responses to smoking cessation, and thus should be considered in developing effective strategies for women to quit smoking.  相似文献   
152.
153.
Gemini surfactants   总被引:12,自引:0,他引:12  
The literature, including patents, describing the emerging area of gemini surfactants is reviewed. The differences in structure/property relationships between gemini and comparable conventional surfactants are described and discussed in terms of their predicted performance properties. Supportive performance data are enumerated.  相似文献   
154.
In this paper, we argue that modelling human action as the execution of predetermined goals and cognition as information processing does not account for peoples experience with emerging technologies, which is as much about values, trust and identity as about executing tasks. We offer a complementary approach to information processing within cognitive ergonomics, which builds on Bruners characterisation of cognition as meaningmaking, and which sees human action as simultaneously creating and executing goals and human cognition as dialogical meaning making. An analysis of field work carried out in two ambulance control centres is employed to exemplify aspects of the creativity and responsivity of work activity that are central to our approach. Finally, in this context, we briefly consider how technological artefacts could be conceptualised as centres of value in an approach to cognitive ergonomics that attempts to accommodate the intellectual, emotional and valuative aspects of work activity.  相似文献   
155.
156.
The authors reanalyzed assessment center (AC) multitrait-multimethod (MTMM) matrices containing correlations among postexercise dimension ratings (PEDRs) reported by F. Lievens and J. M. Conway (2001). Unlike F. Lievens and J. M. Conway, who used a correlated dimension-correlated uniqueness model, we used a different set of confirmatory-factor-analysis-based models (1-dimension-correlated Exercise and 1-dimension-correlated uniqueness models) to estimate dimension and exercise variance components in AC PEDRs. Results of reanalyses suggest that, consistent with previous narrative reviews, exercise variance components dominate over dimension variance components after all. Implications for AC construct validity and possible redirections of research on the validity of ACs are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
157.
IgA class reticulin antibodies were not found in patients with Crohn's disease, ulcerative colitis, and hiatus hernia despite a significant incidence of IgG class reticulin antibodies. None of 56 normal healthy subjects was positive. In contrast, 13 (76%) of the sera from 17 patients with coeliac disease on normal diet were positive for IgA class antibodies as were 19 (20%) of 93 first degree relatives. Seventy-three relatives underwent jejunal biopsy. Grade III (flat) histology was found in 13 and, of these patients, 10 (77%) showed IgA class reticulin antibody in their serum. It is suggested that determination of IgA class reticulin antibodies was a useful test to determine which relative must be biopsied.  相似文献   
158.
Gold and palladium were supported on a mesoporous TiO2 for total oxidation of volatile organic compounds (VOCs). Mesoporous high surface area titania support was synthesised using of Ti(OC2H5)2 in the presence of CTMABr surfactant. After removing the surfactant molecules, 0.5 or 1.5 wt% of palladium and 1 wt% of gold were precipitated on the support by, respectively, wet impregnation and deposition–precipitation methods. The activity for toluene and propene total oxidation of the prereduced samples follows the same order: 0.5%Pd-1%Au/TiO2 > 1.5%Pd/TiO2 > 0.5%Pd/TiO2 > 1%Au-0.5%Pd/TiO2 > 1%Au/TiO2 > TiO2. Moreover, a catalytic comparison with samples based on a conventional TiO2, shows the catalytic advantage of the mesoporous TiO2 support. The promotional effect of gold added to palladium could be partly explained by small metallic particles (TEM), but meanly by metallic particles made up of Au-rich core with a Pd-rich shell. Moreover, the hydrogen TPR profile of 0.5%Pd-1%Au/TiO2 shows only the signal attributed to small PdO particles. Gold also implies a protecting effect of the support under reduction atmosphere. Operando diffuse reflectance infrared fourier transform (DRIFT) spectroscopy was carried on and allowed to follow the VOCs oxidation and the formation of coke molecules, but also a metallic electrodonor effect to the adsorbed molecule which increases in the same order as the activity for oxidation reaction. The presence of coke after test was also shown by DTA–TGA by exothermic signals between 300 and 500 °C and by EPR (g = 2.003).  相似文献   
159.

Background  

Energy drink consumption has continued to gain in popularity since the 1997 debut of Red Bull, the current leader in the energy drink market. Although energy drinks are targeted to young adult consumers, there has been little research regarding energy drink consumption patterns among college students in the United States. The purpose of this study was to determine energy drink consumption patterns among college students, prevalence and frequency of energy drink use for six situations, namely for insufficient sleep, to increase energy (in general), while studying, driving long periods of time, drinking with alcohol while partying, and to treat a hangover, and prevalence of adverse side effects and energy drink use dose effects among college energy drink users.  相似文献   
160.
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