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   1349篇
  免费   28篇
  国内免费   1篇
电工技术   3篇
化学工业   197篇
金属工艺   14篇
机械仪表   12篇
建筑科学   53篇
矿业工程   1篇
能源动力   22篇
轻工业   150篇
水利工程   7篇
石油天然气   4篇
无线电   66篇
一般工业技术   144篇
冶金工业   584篇
原子能技术   17篇
自动化技术   104篇
  2022年   9篇
  2021年   10篇
  2020年   14篇
  2019年   9篇
  2018年   9篇
  2017年   19篇
  2016年   19篇
  2015年   17篇
  2014年   20篇
  2013年   71篇
  2012年   37篇
  2011年   66篇
  2010年   42篇
  2009年   42篇
  2008年   57篇
  2007年   55篇
  2006年   56篇
  2005年   50篇
  2004年   24篇
  2003年   38篇
  2002年   36篇
  2001年   23篇
  2000年   25篇
  1999年   18篇
  1998年   65篇
  1997年   36篇
  1996年   46篇
  1995年   32篇
  1994年   32篇
  1993年   29篇
  1992年   17篇
  1991年   19篇
  1990年   28篇
  1989年   26篇
  1988年   21篇
  1987年   28篇
  1986年   23篇
  1985年   27篇
  1984年   18篇
  1983年   10篇
  1982年   10篇
  1981年   12篇
  1980年   8篇
  1979年   19篇
  1978年   19篇
  1977年   17篇
  1976年   14篇
  1975年   8篇
  1973年   7篇
  1972年   8篇
排序方式: 共有1378条查询结果,搜索用时 343 毫秒
111.
As a result of population pressures, hillsides in the world’s urban areas are being developed at an accelerating rate. This development increases the risk for urban landslides triggered by rainfall or earthquake activity. To counter this risk, four approaches have been employed by landslide managers and urban planners: (1) restricting development in landslide-prone areas; (2) implementing and enforcing excavation, grading, and construction codes; (3) protecting existing developments by physical mitigation measures and (4) developing and installing monitoring and warning systems. Where they have been utilized, these approaches generally have been effective in reducing the risk due to landslide hazards. In addition to these practices, landslide insurance holds promise as a mitigative measure by reducing the financial impact of landslides on individual property owners. Until recently, however, such insurance has not been widely available and, where it is available, it is so expensive that it has been little used.   相似文献   
112.
Response to intervention (RTI) models for identifying learning disabilities rely on the accurate identification of children who, without Tier 2 tutoring, would develop reading disability (RD). This study examined 2 questions concerning the use of 1st-grade data to predict future RD: (a) Does adding initial word identification fluency (WIF) and 5 weeks of WIF progress-monitoring data (WIF-Level and WIF-Slope) to a typical 1st-grade prediction battery improve RD prediction? and (b) Can classification tree analysis improve the prediction accuracy compared to logistic regression? Four classification models based on 206 1st-grade children followed through the end of 2nd grade were evaluated. A combination of initial WIF, WIF-Level, and WIF-Slope and classification tree analysis improved prediction sufficiently to recommend their use with RTI. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
113.
The hypothesis that gender differences in children's adjustment is partially influenced by differences in temperament and interactions with same-sex peers was examined. Fifty-seven predominantly White, middle-class preschoolers (29 boys and 28 girls, M age?=?54.5 months) participated. Measures were taken of children's arousability, problem behaviors, and tendencies to play with same-sex peers. A semester later, children's peer status was assessed. Analyses revealed that arousability and same-sex peer play interacted to predict problem behaviors. For boys high in arousability, play with same-sex peers increased problem behaviors. In contrast, arousable girls who played with other girls were relatively unlikely to show problem behaviors. Moreover, the interaction of arousability and same-sex peer play predicted boys' (but not girls') peer status, and this relation was partially mediated by problem behaviors. The role of gender-related processes is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
114.
A sample of 4,243 residents of Manchester and Newcastle-upon-Tyne, England, aged 50 to 93 yrs, completed the Beck Depression Inventory and a battery of 6 different cognitive tests. Beck scores were low, indicating gradations of dysphoria rather than clinical depression. Beck scores did not vary with age but were significantly higher for women than for men and for disadvantaged than for advantaged socioeconomic groups. Measures of fluid, but not of crystallized, ability declined as age increased. Socioeconomic disadvantage was associated with poorer performance on all cognitive tests. Men scored higher on a test of spatial reasoning, and women scored higher on a test of word definition and on 2 tests of verbal memory and learning. However, after variance associated with these demographic and individual difference variables was considered, and within a range indicative of dysphoria rather than clinical depression, higher Beck scores were associated with significantly poorer performance on both crystallized and fluid measures of cognitive ability. This association was less marked in women than in men, but age, socioeconomic advantage, and estimated lifetime intellectual ability did not act as protective or risk factors for vulnerability of cognitive processes to dysphoria. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
115.
One hundred twenty-one HIV-seropositive (HIV+) individuals and 85 seronegative controls performed a divided-attention task that engaged automatic and controlled attentional processing. Reaction times (RTs) to global and local targets that varied in probability were measured in 5 conditions. A neutral condition where global and local targets were equally probable was included as baseline. Participants showed expected tradeoffs in RTs as a function of target-level probability, with longer RTs to less probable targets and shorter RTs to more probable targets. However, the HIV+ group showed significantly greater costs compared with controls. Results are consistent with previous findings that HIV+ individuals are selectively impaired on tasks of controlled attentional processing, particularly under conditions of divided attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
116.
1 前言电脑和电视含有害物质 ,如铅、水银和六价铬。平均而言 ,每台电视和电脑显示器含有 4磅铅。此外 ,通常在电子产品所用的塑料中添加溴化阻燃剂。如果处置不当 ,这些有毒化学物质就会通过焚烧、焚烧炉灰或填埋液等排放到环境中。除含有害物质外 ,电脑和电视还含有许多有价值的材料 ,如钢、玻璃、塑料和贵金属。重新使用和回收来自废旧电子产品 (即不再被它的主人所需要的电子设备 )的原材料可保护自然资源。它还可避免空气和水污染 ,以及制造新产品带来的温室气体排放问题。最后 ,消费电子产品是固定废物流中增长速度最快的一部分。处…  相似文献   
117.
A survey of aircraft maintenance technicians with the Canadian Forces (N?=?157) found support for a model of burnout and occupational risk assessment. The model depicted employees' assessment of occupational risk as a function of the prevalence and lethalness of workplace hazards, as well as of the amount of control employees experience over their interactions with these hazards. A confirmatory factor analysis, in which LISREL analysis was used, supported an integrated model of risk perception and burnout. In this model, the employee's sense of control in managing occupational hazards was pivotal in both the experience of exhaustion and being at risk at work. Safety training contributed to perceived control and technicians' sense of effectiveness at work. The extension of the burnout construct beyond the human service domain was considered by using the Maslach Burnout Inventory—General Survey (C. Maslach, S. E. Jackson, & A. P. Leiter, 1996). (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
118.
Network outsourcing is an alternative which through advanced technologies, standardization and a close partnership between the client corporation and provider, facilitates an effective and economical means of meeting present and future needs of various corporate user communities. Solutions typically consist of a wide array of services ranging from full operation of the network which includes assumption of assets and personnel to responsibility for various segments of the network such as Help Desk or Vendor Liaison functions.  相似文献   
119.
The authors used a Stroop negative priming paradigm to examine the effects of antipsychotic medication on selective attentional processes. The performance of 14 patients with schizophrenia who were withdrawn from neuroleptic medication was compared with that of 10 medicated patients and 16 matched controls. Results demonstrated an increase in negative priming to normal levels with neuroleptic therapy. In contrast, within-trial interference and facilitation effects appeared to be less sensitive to medication therapy. The sustainment of inhibitory processes over time may differentiate the inhibitory mechanisms of the medication-withdrawn patients from both the medicated patients and the matched controls. The study of sequential inhibitory processes and their response to neuroleptic treatment could be important methods for understanding the temporal parameters associated with inhibition in schizophrenia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
120.
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