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   813篇
  免费   41篇
综合类   1篇
化学工业   229篇
金属工艺   8篇
机械仪表   11篇
建筑科学   36篇
矿业工程   2篇
能源动力   13篇
轻工业   140篇
水利工程   4篇
石油天然气   8篇
无线电   28篇
一般工业技术   88篇
冶金工业   216篇
原子能技术   6篇
自动化技术   64篇
  2023年   9篇
  2022年   31篇
  2021年   41篇
  2020年   24篇
  2019年   24篇
  2018年   21篇
  2017年   22篇
  2016年   21篇
  2015年   14篇
  2014年   22篇
  2013年   45篇
  2012年   35篇
  2011年   36篇
  2010年   38篇
  2009年   42篇
  2008年   38篇
  2007年   40篇
  2006年   36篇
  2005年   22篇
  2004年   30篇
  2003年   19篇
  2002年   21篇
  2001年   16篇
  2000年   9篇
  1999年   21篇
  1998年   14篇
  1997年   21篇
  1996年   19篇
  1995年   9篇
  1994年   8篇
  1993年   13篇
  1992年   5篇
  1991年   2篇
  1990年   9篇
  1989年   6篇
  1988年   6篇
  1987年   6篇
  1986年   7篇
  1985年   9篇
  1984年   7篇
  1983年   3篇
  1982年   7篇
  1981年   3篇
  1980年   2篇
  1979年   2篇
  1978年   6篇
  1976年   5篇
  1974年   2篇
  1973年   3篇
  1962年   1篇
排序方式: 共有854条查询结果,搜索用时 15 毫秒
101.
The skin’s barrier ability is an essential function for terrestrial survival, which is controlled by intercellular lipids within the stratum corneum (SC) layer. In this barrier, free fatty acids (FFAs) are an important lipid class. As seen in inflammatory skin diseases, when the lipid chain length is reduced, a reduction in the barrier’s performance is observed. In this study, we have investigated the contributing effects of various FFA chain lengths on the lamellar phase, lateral packing. The repeat distance of the lamellar phase increased with FFA chain length (C20–C28), while shorter FFAs (C16 to C18) had the opposite behaviour. While the lateral packing was affected, the orthorhombic to hexagonal to fluid phase transitions were not affected by the FFA chain length. Porcine SC lipid composition mimicking model was then used to investigate the proportional effect of shorter FFA C16, up to 50% content of the total FFA mixture. At this level, no difference in the overall lamellar phases and lateral packing was observed, while a significant increase in the water permeability was detected. Our results demonstrate a FFA C16 threshold that must be exceeded before the structure and barrier function of the long periodicity phase (LPP) is affected. These results are important to understand the lipid behaviour in this unique LPP structure as well as for the understanding, treatment, and development of inflammatory skin conditions.  相似文献   
102.
A detailed study of the carrier trapping properties shown by the silicon/oxynitride/oxide gate layers in PowerVDMOS technologies is reported. A quantitative analysis of hole and electron trap densities versus the specific N2O based nitridation process, extracted from Fowler–Nordheim constant current stress kinetics, allows a deep understanding of the role played by those defects in the susceptibility of every nitrided layer.  相似文献   
103.
BACKGROUND: Telemetry monitoring is widely used in hospitals; the importance of being able to monitor and examine dysrhythmias has been universally accepted. Yet it is often used for patients who do not actually require this technology. A model to improve the efficiency of telemetry use entailed the use of an advanced practice nurse (APN; identical to a nurse practitioner) to provide concurrent review and intervention of floating telemetry, which is available for patients independently of the floor location and who do not need an intensive care unit bed. ADDRESSING OVERUSE: The demand for floating telemetry at Hackensack University Medical Center had equaled or exceeded the telemetry availability virtually 100% of the time, even after local guidelines had been disseminated in 1998. The APN carried out concurrent monitoring and intervened with the attending physician when patients were on telemetry for longer than 48 hours and did not meet the local telemetry guidelines. RESULTS: The mean number (standard error [SE]) of hours per patient declined from 65.2 +/- 0.7 hours (95% confidence interval, 63.8 to 66.6 hours) for the 11 months before the intervention to a mean of 49.6 +/- 0.4 hours (95% confidence interval, 48.7 to 50.2 hours) for the 29 months after intervention--representing a decrease of 34% (p < 0.0001). This decrease led to an increase in the number of patients per month put on telemetry. DISCUSSION: The APN model, an aggressive approach that induced change almost immediately, was then applied to other quality improvement projects.  相似文献   
104.
Occupational differences in testosterone concentrations, focusing on actors and ministers, were explored in 3 studies. The 1st examined salivary testosterone in 7 occupational groups and an unemployed comparison group and found actors and football players higher than ministers but no other significant differences. The 2nd examined salivary testosterone in 2 kinds of actors (stage actors and comedians) and 2 kinds of ministers (pastoral ministers and missionaries) and found actors high and ministers low but no differences between subgroups within each occupation. The 3rd examined serum testosterone in entertainers and ministers in a archival sample of military veterans and found entertainers high and ministers low. The results are interpreted in terms of dominance and antisocial tendencies, with the conclusion that these variables are complex and can affect occupational preference in subtle ways. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
105.
A. S. Kaufman (1994) recommends that the Symbol Search, an optional subtest to the WISC-III, be substituted for Coding in the calculation of WISC-III Performance and Full Scale IQ scores. Conversion tables have been published for use with American norms. The authors provide conversion tables for the Canadian-normed WISC-III. The standardization sample consisted of a representative group of 1,100 English-speaking Canadian children. The conversion tables are provided. These tables allow Canadian WISC-III examiners to substitute Symbol Search for Coding in the calculation of the Performance and Full Scale IQ scores. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
106.
An environmental assessment of Legionella bacteria was conducted in five office buildings in the continental United States where no legionellosis was reported. The purpose of this investigation was to (i) determine the presence of Legionella bacteria in potable and non-potable water systems, (ii) provide a baseline information for management, and (iii) evaluate the effectiveness of the remedial actions taken. Water samples were collected from all possible water sources in surveyed buildings. The samples were analyzed by both direct fluorescent antibody microscopy (DFA) and the bacterial cultural method for the presence of Legionella species. Legionella bacteria were detected in some samples collected from various water distribution systems in the buildings. Remedial action was taken to eliminate these bacteria, and case-by-case results are presented.  相似文献   
107.
The paper addresses the local and inter-state connections between water, energy and the environment. Using California and the western USA as a case study, the paper highlights the difficulties of balancing the needs of diverse stakeholders and protecting valuable resources while providing reliable and safe supplies of both water and energy to agricultural, industrial and residential customers. The investigation of these complex relationships is necessary to inform local and national policy decisions regarding the management of water, energy and the environment.  相似文献   
108.
This study describes partner violence in a representative sample of young adults. Physical violence perpetration was reported by 37.2% of women and 21.8% of men. Correlates of involvement in severe physical violence differed by gender. Severe physical violence was more strongly associated with unemployment, low educational attainment, few social support resources, polydrug use, antisocial personality disorder symptoms, depression symptoms, and violence toward strangers for men than for women. Women who were victims of severe physical violence were more likely than men who were victims to experience symptoms of anxiety. The findings converge with community studies showing that more women than men are physically violent toward a partner and with clinical studies highlighting violence perpetrated against women by men with deviant characteristics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
109.
“Advertising's liberated woman incorporates everything the women's movement has fought against.”  相似文献   
110.
The sulfurisation of cuprous bromides and iodides in hydrogen sulfide, at low pressure, leads to the formation of a porous chalcosine layer, as already investigated in the case of chlorides. The step which fixes the conversion rate is the diffusion of the gaseous reagents in the pores of the sulfide formed. Experimental activation energies are 15 and 34 kcal.Mole?1 respectively, at every step of the reaction.  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