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   432篇
  免费   8篇
综合类   1篇
化学工业   74篇
金属工艺   6篇
机械仪表   6篇
建筑科学   23篇
矿业工程   4篇
能源动力   7篇
轻工业   35篇
水利工程   9篇
石油天然气   2篇
无线电   22篇
一般工业技术   62篇
冶金工业   132篇
原子能技术   2篇
自动化技术   55篇
  2024年   4篇
  2023年   6篇
  2022年   9篇
  2021年   10篇
  2020年   14篇
  2019年   9篇
  2018年   4篇
  2017年   10篇
  2016年   8篇
  2015年   8篇
  2014年   12篇
  2013年   19篇
  2012年   12篇
  2011年   28篇
  2010年   12篇
  2009年   12篇
  2008年   22篇
  2007年   9篇
  2006年   11篇
  2005年   9篇
  2004年   15篇
  2003年   11篇
  2002年   11篇
  2001年   12篇
  2000年   6篇
  1999年   8篇
  1998年   20篇
  1997年   8篇
  1996年   12篇
  1995年   10篇
  1994年   4篇
  1993年   6篇
  1992年   4篇
  1990年   3篇
  1989年   5篇
  1988年   6篇
  1986年   5篇
  1985年   4篇
  1984年   6篇
  1982年   7篇
  1981年   3篇
  1980年   3篇
  1979年   3篇
  1977年   8篇
  1976年   8篇
  1975年   5篇
  1973年   2篇
  1972年   2篇
  1971年   2篇
  1970年   2篇
排序方式: 共有440条查询结果,搜索用时 0 毫秒
91.

Context

To date, no studies have adequately examined whether community-level, rather than individual-level, characteristics, are associated with high rates of alcohol-related traffic crashes (ARTC).

Objective

This study aims to identify a proxy measure of ARTC most appropriate to rural communities in New South Wales (NSW), Australia, and to identify community characteristics that predict higher rates of ARTC.

Methods

ARTC (2001–2007) incident data from 20 rural communities in NSW were obtained. Cost data were applied to take account of ARTCs of different severity.

Results

The method used to define a proxy measure of ARTCs for NSW generally was found to be inadequate when applied to local communities within NSW: specifically, two time periods were found to be alcohol-related for local communities only and seven time periods were found to be non-alcohol-related for local communities only. Applying a community-specific proxy measure of ARTCs to 20 communities identified substantial variation in ARTC cost-ratios, ranging from 1.20 to 0.15. Higher cost-ratios were statistically significantly predicted by the proportion of residents who were male and less than 25 years.

Conclusions

Proxy measures of ARTCs represent an ideal method of utilising routinely collected data to identify specific types of ARTCs that are most relevant to a defined community, identify community-specific factors associated with higher rates of ARTCs and measure the impact of interventions tailored to those risk factors. Such measures ought to be community-specific because these results suggest national or provincial-level definitions are not necessarily directly applicable to local communities. These results show substantial variability between communities in their rates of ARTC and identify communities with higher proportions of young males as being at increased risk.  相似文献   
92.
Working memory enables us to hold in our 'mind's eye' the contents of our conscious awareness, even in the absence of sensory input, by maintaining an active representation of information for a brief period of time. In this review we consider the functional organization of the prefrontal cortex and its role in this cognitive process. First, we present evidence from brain-imaging studies that prefrontal cortex shows sustained activity during the delay period of visual working memory tasks, indicating that this cortex maintains on-line representations of stimuli after they are removed from view. We then present evidence for domain specificity within frontal cortex based on the type of information, with object working memory mediated by more ventral frontal regions and spatial working memory mediated by more dorsal frontal regions. We also propose that a second dimension for domain specificity within prefrontal cortex might exist for object working memory on the basis of the type of representation, with analytic representations maintained preferentially in the left hemisphere and image-based representations maintained preferentially in the right hemisphere. Furthermore, we discuss the possibility that there are prefrontal areas brought into play during the monitoring and manipulation of information in working memory in addition to those engaged during the maintenance of this information. Finally, we consider the relationship of prefrontal areas important for working memory, both to posterior visual processing areas and to prefrontal areas associated with long-term memory.  相似文献   
93.
This study used cluster analysis to identify three patterns of sexual health risk behaviors in a sample of adult rape survivors (N=102). Women in the 1st cluster (high risk) reported substantial increases from pre- to postrape in their frequency of sexual activity, number of sexual partners, infrequency of condom use, and frequency of using alcohol and/or drugs during sex. The 2nd cluster (moderate risk) reported increases in frequency of sexual activity and number of partners but mitigated that risk with increased condom use. Survivors in the 3rd cluster (low risk) indicated that their sexual health behaviors had become much less risky postrape. An ecological model predicting cluster membership revealed that individual-level and contextual factors predict patterns of risk behaviors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
94.
We present dye-doped polymer nanoparticles that are able to detect mercury in aqueous solution at parts per billion levels via fluorescence resonance energy transfer (FRET). The nanoparticles are prepared by reprecipitation of highly fluorescent conjugated polymers in water and are stable in aqueous suspension. They are doped with rhodamine spirolactam dyes that are nonfluorescent until they encounter mercury ions, which promote an irreversible reaction that converts the dyes to fluorescent rhodamines. The rhodamine dyes act as FRET acceptors for the fluorescent nanoparticles, and the ratio of nanoparticle-to-rhodamine fluorescence intensities functions as a ratiometric fluorescence chemodosimeter for mercury. The light harvesting capability of the conjugated polymer nanoparticles enhances the fluorescence intensity of the rhodamine dyes by a factor of 10, enabling sensitive detection of mercury ions in water at levels as low as 0.7 parts per billion.  相似文献   
95.
The authors examined the effect of learning on multiple encounters with sources of social ambiguity in individuals with generalized social phobia (GSP). The authors modified G. B. Simpson and H. Kang's (1994) paradigm and presented prime-target word pairs to individuals with GSP and nonanxious controls (NACs) to prime threat and nonthreat meanings of homographs and examine the effect of this priming on later encounters with that homograph. Consistent with previous research, NACs showed faster response latencies naming a target primed by a homograph with the same meaning activated in two successive trials than naming the same target primed by an unrelated word. Furthermore, NACs showed slower response latencies naming a target when a different meaning of the homograph prime was activated in successive trials than naming a target primed by an unrelated word. GSP participants did not show this pattern in learning a nonthreat meaning of a homograph. These results support the hypothesis that a faulty learning mechanism may be involved in social anxiety. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
96.
The motions of grinding media and powder in an attritor canister were studied by means of filming the agitated charge and frame-by-frame scrutiny of the footage. In conjunction with auxiliary experiments, this permitted semiquantitative analysis of the milling action. In particular, the mill can be divided into several regions characterized by different balances between direct impacts and rolling/sliding of the grinding media. Simple calculations suggest that impacts are more capable of effecting mechanical alloying (MA) than are rolling or sliding events in an attritor. Powder circulation within an operating mill was also investigated. Based on the results and the accompanying analysis, concepts for improved attritor design are presented. D. Maurice is formerly a Graduate Student, Department of Materials Science and Engineering, University of Virginia, Charlottesville, VA 22903  相似文献   
97.
Practice variability has been shown to enhance transfer of training. The purpose of the present study was to examine the role of self-efficacy generality as a motivational mechanism in explaining the relationship between practice variability and transfer. Undergraduate students (N = 82) were randomly assigned to 1 of 2 training conditions (constant or variable) for a computer decision-making task. Measures of self-efficacy (intensity and generality) and transfer (near and far) were assessed. The results provided support for some of the hypothesized relationships. Specifically, practice variability led to increased self-efficacy generality. Both self-efficacy intensity and generality influenced far transfer performance, although only self-efficacy generality served as a mediator between practice variability and far transfer. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
98.
    
In Saccharomyces cerevisiae, a complex comprising more than 20 different polypeptides assembles in a ring at the neck between the mother cell and the bud. This complex functions to coordinate cell morphology with cell division. Relatively little is known about this control system, including the physical relationships between the components of the neck ring. This study addressed the assembly interactions of three components of the ring, specifically the protein kinases Elm1p and Hsl1p and the septin Cdc12p. Specific amino acid substitutions in each of these three proteins were identified that either cause or suppress a characteristic phenotype of abnormally elongated cells and delay in the G(2)-M transition. Each protein was fused to green fluorescent protein, and its ability to localize at the neck was monitored in vivo in cells of various genotypes. Localization of Hsl1p to the neck requires Elm1p function. Elm1p localized normally in the absence of Hsl1p, although a specific point mutation in Hsl1p clearly affected Elm1p localization. The cdc12-122 mutation prevented assembly of Elm1p or Hsl1p into the neck ring. Normal assembly of Cdc12p at the neck was dependent upon Elm1p and also, to a smaller extent, on Hsl1p. Ectopic localization of Cdc12p at the bud tip was observed frequently in elm1 mutants and also, to a lesser extent, in hsl1 mutants. Thus, Elm1p is a key factor in the assembly and/or maintenance of Hsl1p, as well as at least one septin, into the bud neck ring.  相似文献   
99.
100.
ABSTRACT

Local governments must provide public access to records such as court proceedings, deeds, marriage licenses, birth, and death records, and so on, often on tight budgets. This article focuses on how a local agency, the Clerk of Courts office in Lake County, Florida, used a planning process developed by the National Center for State Courts. This process was loosely coupled with the principles of sensemaking (Weick, 1995 Weick, K. E. 1995. Sensemaking in organizations. Thousand Oaks, CA: Sage Publications.  [Google Scholar]) to stay ahead of the curve concerning changes that would significantly affect its records management system. By applying the scanning methods, the organization was able to paint a plausible picture of its future environment that allowed it to attack the issues related to legislative changes in its electronic records management (ERM) practices proactively rather than reactively.  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