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   85篇
  免费   3篇
电工技术   1篇
化学工业   20篇
金属工艺   1篇
建筑科学   6篇
轻工业   6篇
水利工程   1篇
无线电   20篇
一般工业技术   4篇
冶金工业   18篇
原子能技术   1篇
自动化技术   10篇
  2021年   2篇
  2019年   1篇
  2018年   4篇
  2017年   2篇
  2016年   2篇
  2015年   1篇
  2014年   3篇
  2013年   6篇
  2011年   4篇
  2010年   4篇
  2009年   7篇
  2008年   5篇
  2007年   7篇
  2006年   1篇
  2005年   1篇
  2004年   1篇
  2003年   4篇
  2002年   1篇
  2001年   1篇
  2000年   1篇
  1999年   3篇
  1998年   2篇
  1997年   5篇
  1996年   3篇
  1995年   3篇
  1994年   2篇
  1993年   2篇
  1992年   1篇
  1990年   1篇
  1988年   2篇
  1986年   1篇
  1985年   1篇
  1984年   2篇
  1983年   1篇
  1981年   1篇
排序方式: 共有88条查询结果,搜索用时 546 毫秒
81.
82.
Examined cessation among 630 smokers who quit abruptly on their own. Continuous, complete abstinence rates were 33% at 2 days, 24% at 7 days, 22% at 14 days, 19% at 1 mo, 11% at 3 mo, 8% at 6 mo postcessation, and 3% at 6 mo with biochemical verification. Slipping (smoking an average of less than 1 cigarette/day) was common (9% to 15% of Ss) and was a strong predictor of relapse; however, 23% of long-term abstainers slipped at some point. Results challenge beliefs that most smokers can initially stop smoking and that most relapse occurs later on postcessation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
83.
An expression for the error probability of M-ary noncoherent frequency-shift keying (NCFSK) for locally optimum threshold detection in non-Gaussian noise, frequently encountered in practice, is derived, which demonstrates that a significant improvement in performance can be achieved when M is greater than two.  相似文献   
84.
Organizations that align technology with objectives, people, and processes through a six-step rightsizing planning process hold the key to successful implementation of a client/server architecture.  相似文献   
85.
Used multiple regression methods to investigate the diagnostic policies for hyperactivity (hyperkinesis) used by 16 experienced clincial psychologists. Individual analyses were made on each S's set of diagnoses of children who had been described in terms of 19 cues, including reports of home and school behavior, clinical observation, and test results. Linear models accounted for a reasonably large amount of the diagnostic variance. Although Ss' diagnoses were all intercorrelated, there were substantial individual differences among them in terms of both the cues used and the number diagnosed hyperactive. Results cast doubt on the presumption of professional consensus on the behavioral symptoms of a hyperactivity syndrome and suggest that the diagnostician may be an important source of the observed symptom heterogeneity of hyperactive children. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
86.
Body dysmorphic disorder (BDD) is a distressing body image disorder that involves excessive preoccupation with physical appearance in a normal appearing person. Prior case reports of behavior therapy were encouraging, but no controlled evaluation of behavior therapy or any other type of treatment had been conducted. In the present study, 54 BDD subjects were randomly assigned to cognitive behavior therapy or no treatment. Patients were treated in small groups for eight 2-hour sessions. Therapy involved modification of intrusive thoughts of body dissatisfaction and overvalued beliefs about physical appearance, exposure to avoided body image situations, and elimination of body checking. Body dysmorphic disorder symptoms were significantly decreased in therapy subjects and the disorder was eliminated in 82% of cases at posttreatment and 77% at follow-up. Overall psychological symptoms and self-esteem also improved in therapy subjects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
87.
Emerging ultra-wideband (UWB) technology offers a great potential for the design of high-speed short-range communications. However, in order for a UWB device to coexist with other devices, the transmitted power level of UWB is strictly limited by the FCC spectral mask. Such limitation poses a significant design challenge to any UWB system. An efficient management of the limited power is thus a key feature to fully exploit the advantages of UWB. In this paper, a cross layer multiuser multiband UWB scheme is proposed to obtain the optimal subband and power allocation strategy. Optimization criteria involve minimization of power consumption under the constraints on the packet error rate, the data rate, and the FCC limit. To ensure the system feasibility in variable channel conditions, an algorithm to jointly manage the rate assignment of UWB devices, subband allocation, and power control is proposed. A computationally inexpensive suboptimal approach is also developed to reduce the complexity of the problem, which is found to be NP hard. Simulation results under UWB channel model specified in the IEEE 802.15.3a standard show that the proposed algorithm achieves comparable performances to those of the complex optimal full search approach, and it can save up to 61% of transmit power compared to the current multiband scheme in the standard proposal. Moreover, the proposed algorithm can obtain the feasible solutions adaptively when the initial system is not feasible for the rate requirements of the users  相似文献   
88.
To assess the current risks to consumers from Campylobacter and Salmonella in raw chicken products sold in the Republic of Ireland, a retail survey was undertaken to define their prevalence. Samples (n = 510) were analyzed using protocols based on ISO 10272-1:2006 and ISO 6579:2002. Processor codes on pack labels showed that 67% of samples were produced in the Republic of Ireland and 25% in the United Kingdom. Salmonella was present in 5.1% of samples, but the eight serovars found caused less than 7% of human salmonellosis reported in the Republic of Ireland. The results suggest that on-farm controls to limit Salmonella infection of broilers have been successful and that in Ireland raw chicken is not a significant cause of salmonellosis in humans. The overall prevalence of Campylobacter spp. was 84.3%. Isolation by the ISO method found 52.7% of samples to be positive, but overgrowth by contaminants was frequently evident. Therefore, in addition to enrichment, an homogenized sample was plated directly onto modified charcoal cefoperazone deoxycholate agar, and this detected a further 31.6%. Speciation of isolates (n = 426) determined that 67% were Campylobacter jejuni and 32% were Campylobacter coli. These species are the most common cause of campylobacteriosis in man. The results indicate that there is a need for poultry producers to introduce interventions to minimize the exposure of consumers in the Republic of Ireland to Campylobacter spp., as has been successfully done for Salmonella.  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