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   685篇
  免费   24篇
  国内免费   9篇
电工技术   2篇
综合类   10篇
化学工业   36篇
金属工艺   6篇
机械仪表   2篇
建筑科学   80篇
能源动力   3篇
轻工业   23篇
水利工程   1篇
石油天然气   1篇
武器工业   1篇
一般工业技术   14篇
冶金工业   478篇
自动化技术   61篇
  2024年   1篇
  2023年   5篇
  2022年   12篇
  2021年   20篇
  2020年   9篇
  2019年   10篇
  2018年   7篇
  2017年   8篇
  2016年   10篇
  2015年   10篇
  2014年   15篇
  2013年   9篇
  2012年   25篇
  2011年   57篇
  2010年   49篇
  2009年   53篇
  2008年   40篇
  2007年   39篇
  2006年   38篇
  2005年   51篇
  2004年   62篇
  2003年   66篇
  2002年   47篇
  2001年   29篇
  2000年   2篇
  1999年   2篇
  1998年   2篇
  1997年   1篇
  1996年   2篇
  1995年   4篇
  1994年   2篇
  1993年   4篇
  1992年   3篇
  1991年   1篇
  1990年   4篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1985年   1篇
  1973年   1篇
  1971年   1篇
  1968年   1篇
  1967年   1篇
  1966年   1篇
  1964年   2篇
  1962年   1篇
  1961年   2篇
  1959年   1篇
  1957年   1篇
  1956年   3篇
排序方式: 共有718条查询结果,搜索用时 15 毫秒
101.
Hemodialysis patients characteristically suffer from a range of unpleasant symptoms. Uremic pruritus effects close to half of the chronic kidney disease population, reducing quality of life and associated with increased mortality. Its pathophysiology though is poorly understood; currently deployed therapeutic approaches are ineffective. Excessive levels of skin and soft tissue sodium accumulate in dialysis patients, producing a range of biological consequences, including inflammation. We report an index case of a hemodialysis patient with debilitating pruritus and extreme levels of tissue sodium, measured with Sodium-23 magnetic resonance imaging. Both the tissue sodium loading and pruritus responded fully to initiation of expanded hemodialysis therapy with a recently introduced medium cutoff dialysis membrane-based dialyzer.  相似文献   
102.
The present field study investigated mental health aspects at intralogistics workplaces, as cognitive and social demands have largely changed in this branch. Within a cross-sectional, mixed methods study design, forty-one intralogistics employees completed a survey about their working conditions and mental states. Further, nine workers participated in a systematic, qualitative group interview to obtain intralogistics specific job resources and job demands. The results were compared to known mechanisms from a long-established psychological model (the Job-Demands and Resources model, JD-R model) to evaluate if these general assumptions still apply at modern working conditions. As expected and in line with the JD-R model, regression analyzes supported that job resources predicted work engagement (p < .05) and job demands predicted burnout symptoms (p < .001) even at modern intralogistics workplaces. However, no interaction effects (Job Demands X Job Resources) were found. The qualitative interviews highlighted several job demands and job resources, which were reported as especially relevant for modern intralogistics workplaces by the participants. Based on the findings, practical recommendations were evolved for the improvement of mental health at intralogistics workplaces. Job resources, for example process transparency or respectful and esteeming leadership behavior, can be increased in order to improve work engagement. Job demands, for example task interruptions, excessive time pressure or profuse exposure to physical stress should be controlled to reduce burnout symptoms.  相似文献   
103.
Occupant responses and indoor environment characteristics were recorded and compared in five mechanically and four naturally ventilated open-plan office buildings by using a simple approach that enabled us to survey many buildings simultaneously. All occupant responses were obtained during one afternoon. In a pre-experiment, temperature and the concentration of CO2 were monitored in 2–10 locations/office to evaluate the variation throughout the offices. A representative measurement point was subsequently selected and measurements of the same parameters were made during one week. All offices were monitored during the same week and occupant responses to the indoor environment were collected via the internet on the same day within that week. The temperature and the CO2 concentration varied more and were in some cases higher in the naturally ventilated buildings, but occupant responses in terms of symptoms and adverse perceptions differed only modestly between the two building types. Although rarely supported by statistical significance, the results indicated a somewhat higher degree of satisfaction with the indoor environment and a lower prevalence/intensity of symptoms among the occupants in the naturally ventilated buildings.  相似文献   
104.
Seppänen O  Fisk WJ 《Indoor air》2002,12(2):98-112
This paper provides a synthesis of current knowledge about the associations of ventilation system types in office buildings with sick building syndrome (SBS) symptoms and discusses potential explanations for the associations. Most studies completed to date indicate that relative to natural ventilation, air conditioning, with or without humidification, was consistently associated with a statistically significant increase in the prevalence of one or more SBS symptoms, by approximately 30 to 200%. In two of three analyses from a single study (assessments), symptom prevalences were also significantly higher in air-conditioned buildings than in buildings with simple mechanical ventilation and no humidification. The available data also suggest, with less consistency, an increase in risk of symptoms with simple mechanical ventilation relative to natural ventilation. Insufficient information was available for conclusions about the potential increased risk of SBS symptoms with humidification or recirculation of return air. The statistically significant associations of mechanical ventilation and air conditioning with SBS symptoms are much more frequent than expected from chance and also not likely to be a consequence of confounding by several potential personal, job, or building-related confounders. Multiple deficiencies in HVAC system design, construction, operation, or maintenance, including some which cause pollutant emissions from HVAC systems, may contribute to the increases in symptom prevalences but other possible reasons remain unclear.  相似文献   
105.
Perceived air quality, Sick Building Syndrome (SBS) symptoms and productivity were studied in a normally furnished office space (108 m3) ventilated with an outdoor airflow of 3, 10 or 30 L/s per person, corresponding to an air change rate of 0.6, 2 or 6 h-1. The temperature of 22 degrees C, the relative humidity of 40% and all other environmental parameters remained unchanged. Five groups of six female subjects were each exposed to the three ventilation rates, one group and one ventilation rate at a time. Each exposure lasted 4.6 h and took place in the afternoon. Subjects were unaware of the intervention and remained thermally neutral by adjusting their clothing. They assessed perceived air quality and SBS symptoms at intervals, and performed simulated normal office work. Increasing ventilation decreased the percentage of subjects dissatisfied with the air quality (P < 0.002) and the intensity of odour (P < 0.02), and increased the perceived freshness of air (P < 0.05). It also decreased the sensation of dryness of mouth and throat (P < 0.0006), eased difficulty in thinking clearly (P < 0.001) and made subjects feel generally better (P < 0.0001). The performance of four simulated office tasks improved monotonically with increasing ventilation rates, and the effect reached formal significance in the case of text-typing (P < 0.03). For each two-fold increase in ventilation rate, performance improved on average by 1.7%. This study shows the benefits for health, comfort and productivity of ventilation at rates well above the minimum levels prescribed in existing standards and guidelines. It confirms the results of a previous study in the same office when the indoor air quality was improved by decreasing the pollution load while the ventilation remained unchanged.  相似文献   
106.
Genetic effects on adolescent depression have been consistently reported, but little is known about mediating pathways from the distal genotype to resultant behavioral symptoms. Identifying intermediate risk markers may provide clues on these pathways. In the present study, longitudinal twin and sibling data were used to address 3 issues pertaining to attributional style as a putative marker of genetic risk for adolescent depression: state independence by assessing predictive effects between attributional style and depressive symptoms, heritability of attributional style at different time points, and genetic links between attributional style and depressive symptoms characterizing concurrent and longitudinal associations. The authors further examined whether these predictive and genetic links varied across levels of stress, age, and gender. Negative attributions preceded, co-occurred with, and followed symptoms. The predictive association between earlier negative attributions and later depressive symptoms did not differ by stress, age, or gender. Attributional style was moderately heritable at both time points. Genetic links with concurrent and prospective depressive symptoms were larger in individuals reporting higher levels of stress, who were older and female. Implications for attributional style as a marker reflecting genetic risks are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
107.
The present study tested the impact of a parent behavior-management intervention on child depressive and internalizing symptoms. One hundred eighty-one children were randomly assigned to receive a videotape modeling parenting intervention, the Incredible Years, or to a wait-list control group. Children who received the intervention were more likely to have lower mother-rated mood and internalizing symptoms at post-treatment, compared with children in a wait-list control group. The effect sizes observed in the present intervention fell in the small-to-medium range for the sample as a whole, and some evidence supported the authors' hypothesis that effects would be strongest for children with baseline internalizing symptoms in the clinical range. Subsequent analyses also revealed that perceived changes in parenting effectiveness mediated the effect of treatment on children's post-treatment internalizing symptoms. The finding was consistent with study hypotheses and social learning explanations of child internalizing symptoms that guided selection of putative mechanisms. Implications for counseling psychologists and for designing interventions and prevention strategies for children with internalizing symptoms are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
108.
Pathways linking parental depressive symptoms, adult relationship insecurity, interparental conflict, negative parenting, and children's psychological adjustment (internalizing symptoms and externalizing problems) were assessed using a 3-wave longitudinal research design. Two-parent families (N = 352) with 11- to 13-year-old children (179 boys, 173 girls) participated in the study. Maternal and paternal depressive symptoms were associated with insecurity in adult close relationships assessed 12 months later, which was concurrently related to heightened levels of interparental conflict. Controlling for children's initial symptom levels, interparental conflict was related to child appraisals of father and mother rejection assessed an additional 12 months later, which were related to children's internalizing symptoms and externalizing problems, respectively. Results are discussed with regard to the implications for understanding the complex interplay between adult depressive symptoms, attributions in close adult relationships, interparental conflict, negative parenting, and children's psychological adjustment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
109.
This study investigated the relationship between coping styles and police recruits' stress responses and performance during a stressful event and the relationship between coping styles and traumatic symptoms. Recruits participated in a simulated stressful policing situation and were scored by expert raters. Distress measures included biological and psychological indicators of stress. Coping styles were associated with subjective and physiological distress but not with performance. Different coping styles were associated with different patterns of traumatic symptoms in the participants. Police recruits appear to rely on their training and skill sets in stressful situations regardless of how they manage their emotional response. Furthermore, the results suggest that different posttraumatic stress disorder manifestations may represent different pathologies, each associated with a different style of coping. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
110.

Objective

To evaluate the effect of a total ban on smoking indoors in restaurants and other hospitality business premises in Norway, on respiratory symptoms among workers in the industry.

Methods

Phone interviews with 1525 employees in the hospitality business were conducted immediately before the enacting of the law. In a follow‐up study five months later, 906 of the workers from the baseline sample participated. Questions were asked on demographic variables, passive smoking exposure, personal smoking, attitudes towards the law, and five respiratory symptoms. Change in symptom prevalence was analysed with McNemar''s test and with analysis of variance (ANOVA) for repeated measures.

Results

The prevalence of all five symptoms declined after the ban; for morning cough from 20.6% to 16.2% (p < 0.01); for daytime cough from 23.2% to 20.9%; for phlegm cough from 15.3% to 11.8% (p < 0.05); for dyspnoea from 19.2% to 13.0% (p < 0.01); and for wheezing from 9.0% to 7.8%. ANOVA showed that the largest decline in symptom prevalence was seen among workers who themselves gave up smoking, and subjects with a positive attitude towards the law before it took effect.

Conclusion

A significant decrease in respiratory symptoms among service industry workers was found five months after the enacting of a public smoking ban.  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