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   257篇
  免费   14篇
电工技术   2篇
化学工业   50篇
金属工艺   2篇
机械仪表   6篇
建筑科学   6篇
能源动力   5篇
轻工业   28篇
水利工程   2篇
石油天然气   1篇
无线电   55篇
一般工业技术   45篇
冶金工业   22篇
原子能技术   2篇
自动化技术   45篇
  2023年   3篇
  2022年   5篇
  2021年   17篇
  2020年   7篇
  2019年   7篇
  2018年   12篇
  2017年   9篇
  2016年   8篇
  2015年   10篇
  2014年   11篇
  2013年   15篇
  2012年   14篇
  2011年   20篇
  2010年   7篇
  2009年   7篇
  2008年   21篇
  2007年   16篇
  2006年   29篇
  2005年   9篇
  2004年   1篇
  2003年   5篇
  2002年   2篇
  2001年   2篇
  2000年   1篇
  1999年   3篇
  1998年   7篇
  1997年   3篇
  1996年   1篇
  1995年   1篇
  1994年   2篇
  1993年   1篇
  1991年   3篇
  1990年   1篇
  1987年   2篇
  1981年   2篇
  1976年   2篇
  1973年   2篇
  1970年   2篇
  1958年   1篇
排序方式: 共有271条查询结果,搜索用时 109 毫秒
91.
Several subjective rating schemes were investigated to determine which might be the most effective for use in designing and evaluating car seats, and what relationships exist among these schemes. Participants (n=27) completed short-term driving sessions, in six combinations of seats (from vehicles ranked high and low on overall comfort), vehicle class (sedan and SUV), and driving venue (lab-based and field). Overall ratings were obtained, as well as separate measures of comfort and discomfort of the whole body and local body parts. No association was found between subjective ratings and a publicly available overall vehicle comfort score (J.D. Power and Associates’ Comfort Score), implying that other factors besides sitting comfort/discomfort (and car seats) account for overall vehicle comfort. Other major results were that contemporary car seats appear to best accommodate those of middle stature, that packages/seats of sedans were preferred over those of SUVs, that separate processes appeared to be involved in determining whole body comfort and discomfort, and that ratings of comfort were most effective at differentiating among the car seats. Finally, a scheme for the use of subjective ratings was suggested: discomfort ratings for ensuring basic seat requirements (pain prevention-oriented) and comfort ratings for promoting advanced seat requirements (pleasure promotion-oriented).

Relevance to industry

Evidence regarding the advantages and disadvantages of different subjective rating schemes can facilitate future design and evaluation of automotive seats.  相似文献   

92.
With the ubiquity of handheld devices (such as smart phones and PDAs) and the availability of a wide range of mobile services (such as mobile banking, road traffic updates, and weather forecast), people can nowadays access information and conduct online transactions virtually anywhere and anytime. In such flexible, dynamic but less reliable environment, transaction management technology is believed to provide service reliability and data consistency. Indeed, in mobile and ubiquitous environments where devices as well as services can seamlessly join and leave the ubiquitous network; transaction management can be very helpful during the recovery of services from failure. Current transaction models and commit protocols do not take into account context information. However, in mobile environments, it is imperative to consider context information in the commit of a transaction—i.e., a transaction can be successfully completed if it meets the required context. In this paper, we propose a new model for context-aware transactions and their performance management in mobile environments. Unlike conventional transactions, context-aware transactions adapt to the required context. By context, we mean the service’s context as well as the users’ context that includes users’ needs and preferences. This paper designs and develops the proposed transaction model and evaluates its performance in terms of time and message complexities as well as transaction’s throughput.  相似文献   
93.
The aim of the present study was to optimise the photocatalytic degradation of a mixture of six commercial azo dyes, by exposure to UV radiation in an aqueous solution containing TiO(2)-P25. Response surface methodology, based on a 3(2) full factorial experimental design with three replicates was employed for process optimisation with respect to two parameters: TiO(2) (0.1-0.9 g/L) and H(2)O(2) (1-100 mmol/L). The optimum conditions for photocatalytic degradation were achieved at concentrations of 0.5 g TiO(2)/L and 50 mmol H(2)O(2)/L, respectively. Dye mineralisation was confirmed by monitoring TOC, conductivity, sulfate and nitrate ions, with a sulfate ion yield of 96% under optimal reactor conditions. Complete decolorisation was attained after 240 min irradiation time for all tested azo-dyes, in a process which followed a pseudo-first kinetic order model, with a kinetic rate constant of approximately 0.018 min(-1). Based on these results, this photocatalytic process has promise as an alternative for the treatment of textile effluents.  相似文献   
94.
95.
The Helicobacter Pylori has been indicated as a pathologic agent in the pathogenesis of antral gastritis, gastric and duodenal ulcers and probably in gastric cancer. Due to the high incidence of this infection in our place, we decided to look for a diagnostic method quick to perform, sensitive, reliable and no invasive. The breath test of 14C urea, based in the production of urea by the H. Pylori, represents this alternative. We have found, using does of 1 microCi, a high correlation with the diagnosis of H. Pylori by biopsies. We determined as negative less than 100 DPM, doubtful between 100 and 200 DPM and positive more than 200 DPM. The high pick of the curve keeps tight relation with the degree of infection. We checked this when we suppressed the H. Pylori with bismuth subsalicylate. The breath 14C Urea test showed high sensitivity (100%) and specificity (85.71%). We conclude that this breath test is an alternative way of diagnosing and follow up for H. Pylori infections. It is highly sensitive, reproducible and no invasive.  相似文献   
96.
97.
最近有一些科技伙伴关系,似乎很难想出哪位合作伙伴是从强势地位出牌,哪位也许是在虚张声势。如同扑克玩家们一样,科技公司为各自利益而施展全力。但是,伙伴关系经常使这种“不惜一切代价获胜”的思想变得模糊。以2005年11月底宣布的高通(Qualcomm)公司  相似文献   
98.
This paper presents cost-outcome analyses of five injury prevention efforts in Native American jurisdictions: a safety-belt program, a streetlight project, a livestock control project, a drowning prevention program, and a suicide prevention and intervention program. Pre- and post-intervention data were analyzed to estimate projects' impact on injury reduction. Projects' costs were amortized over the time period covered by the evaluation or over the useful life of physical capital invested. Projects' savings were calculated based on estimated reduction in medical and public program expenses, on estimated decrease in lost productivity, and on estimated quality adjusted life years saved.All projects yielded positive benefit-cost ratios. The net cost per quality adjusted life years was less than zero (i.e. the monetary savings exceeded project costs) for all but one of the projects.  相似文献   
99.
半导体工业进入了利用摩尔定律所述效应--IC中集成的晶体管数每1 8个月左右翻一番--的第三个十年.事实上,元件密度更大的IC和单片系统(SoC)设计技术正在与因特网和新兴的统一网站相结合,使第三个十年成为这一丰富多彩的技术工业最激动人心的时期.  相似文献   
100.
In Montreal (Canada), the mean annual atmospheric Mn concentrations between 1981 and 1990 were stable, followed by a decrease of almost 50% from 1990 to 1992. The reason for such a decrease in Mn is probably the shutdown of a large manganese alloy production plant in Beauharnois, approximately 25 km from Montreal. The objective of this study is to assess the level of air and soil contamination by Mn in the vicinity of this ferroalloy plant more than 10 years after its closure. Air and soil were sampled over 5 days at two and three sites, respectively. Site 1 was located 10 m NE of the closed plant, in the direction of the prevailing SW-NE winds. Sites 2 and 3 were at 50 and 800 m SE from the plant. Air samples were collected in order to determine total (MnT) and respirable (MnR). Soil samples were taken in the surface and subsurface strata. The results show that site 1 is extremely polluted with a mean Mn concentration in surface strata of 2,66,000+/-45,000 ppm and 2,83,000+/-23,000 ppm in the subsurface strata, while the average MnT and MnR are 21.9+/-13.7 and 3.5+/-3.9 microg/m(3), respectively. The explanation for this contamination is direct deposition on the soil of solid Mn-rich residue and atmospheric erosion of Mn particles. The situation should be remediated by the public authority with high priority.  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