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   910篇
  免费   37篇
  国内免费   5篇
电工技术   11篇
综合类   37篇
化学工业   29篇
金属工艺   43篇
机械仪表   18篇
建筑科学   143篇
矿业工程   57篇
能源动力   25篇
轻工业   77篇
水利工程   36篇
石油天然气   34篇
无线电   31篇
一般工业技术   113篇
冶金工业   41篇
原子能技术   29篇
自动化技术   228篇
  2023年   9篇
  2022年   6篇
  2021年   13篇
  2020年   18篇
  2019年   17篇
  2018年   9篇
  2017年   18篇
  2016年   31篇
  2015年   32篇
  2014年   58篇
  2013年   45篇
  2012年   43篇
  2011年   58篇
  2010年   58篇
  2009年   54篇
  2008年   70篇
  2007年   56篇
  2006年   50篇
  2005年   32篇
  2004年   42篇
  2003年   34篇
  2002年   27篇
  2001年   33篇
  2000年   14篇
  1999年   19篇
  1998年   18篇
  1997年   10篇
  1996年   12篇
  1995年   15篇
  1994年   7篇
  1993年   7篇
  1992年   9篇
  1991年   7篇
  1990年   3篇
  1989年   4篇
  1987年   1篇
  1986年   3篇
  1982年   2篇
  1981年   3篇
  1977年   1篇
  1975年   1篇
  1972年   2篇
  1962年   1篇
排序方式: 共有952条查询结果,搜索用时 15 毫秒
1.
根据近十年地质调查预算标准地区调整系数跟踪评估意见,众多地质调查项目承担单位认为地区调整系数总体合理,满足地质调查项目预算管理的需要,但在个别地区存在一些系数不适应问题。本文梳理了地区调整系数的沿革,总结整理了地区调整系数使用中存在的问题,分析了影响地区费用支出差异因素,建立了地区调整系数修订加分模型,在此基础上提出了地区调整系数修订模式探索,为下一步开展地区调整系数修订测算工作打下基础。  相似文献   
2.
This paper analyses the perception of Artificial Intelligence (AI) by individuals in Spain and the factors associated with it. It uses data from 6308 individuals from a 2018 Spanish survey. A binary logit regression model is formulated and estimated for the attitude towards robots and AI and its possible determinants. As main results are that a gender gap is detected, and that people have a negative attitude if they are not interested in scientific discoveries and technological developments and if AI and robots are not useful at work.  相似文献   
3.
Business process management (BPM) research conceptualizes BPM culture as a type of organizational culture that supports BPM. No quantitative fieldwork has so far examined how such a supporting role manifests itself. We study the relationship between BPM culture, BPM methods, and process performance empirically. Our analysis of multiple survey data sets from a total of 581 practitioners of multiple industries suggests that BPM methods indirectly contribute to process performance by establishing a BPM culture. This finding updates the prevalent assumption that the correct application of methods yields direct performance benefits. We discuss several implications for theory and practice.  相似文献   
4.
PurposeThe purpose of this survey was to better understand scleral lens (SL) practitioners’ fitting preferences and minor SL complications and their subsequent treatments.MethodPractitioners who attended the 2017 Global Specialty Lens Symposium were asked to complete an electronic questionnaire that was created by the investigators, a survey that asked practitioners about their SL fitting experience and preferences, their patients’ experience with poor SL wetting, SL fogging, ocular symptoms (redness, pain/discomfort, dryness), and blurred central and side vision, and how the practitioners treated these conditions.ResultsThis study analyzed data from 164 SL practitioners. The practitioners had been in practice for 16.3 ± 13.4 years, had been fitting SL for 5.5 ± 5.0 years, and fit 7.4 ± 7.1 SL/month. Practitioners preferred a SL with a final central corneal clearance of ∼200 μm and an overall diameter between 15.1 mm to 16.5 mm. Poor SL wetting (90.8% of practitioners documented condition), SL fogging (84.8%), blurred central vision (40.2%), ocular redness (34.8%), ocular dryness (24.4%), ocular pain/discomfort (20.7%), and blurred side vision (12.8%) were encountered by the practitioners. Practitioners preferred treating poor wetting and fogging with lens removal, cleaning, and reapplication, blurred central vision with a lens power change, blurred side (peripheral) vision, ocular redness, and ocular pain with a lens parameter change, and dryness with artificial tears.ConclusionsMost SL practitioners preferred a SL central corneal clearance of ∼200 μm, and they occasionally encountered SL-related complications in their practice, which they treated similarly to corneal gas permeable CLs.  相似文献   
5.
田树斌 《世界有色金属》2020,(4):263-263,265
随着科学技术持续进步,大型工程的建设规模也是越来越大,现实的工程项目中越来越重视某些复杂地形地质的岩土工程勘探工作,社会层面上也越加重视勘察人员的素质教育以及责任义务的教育工作,切实提升勘察人员的勘察技术。所以本文作者基于复杂地形地质条件下岩土工程的勘察工作进行详细的总结分析。  相似文献   
6.
Injuries to the hollow organs of the lower digestive system carry substantial risk of complication due to infection and blood loss, and commonly require invasive abdominal surgery to diagnose and treat. The causes of, and risk factors for, lower abdomen injury in automobile collisions are poorly understood. The goal of this study was to investigate the risk factors and potential mechanisms of hollow-organ, lower abdomen injury in belted automobile occupants in frontal collisions.  相似文献   
7.
Approximately 1,701,500 people were employed as heavy and tractor-trailer truck drivers in the United States in 2012. The majority of them were long-haul truck drivers (LHTDs). There are limited data on occupational injury and safety in LHTDs, which prompted a targeted national survey. The National Institute of Occupational Safety and Health conducted a nationally representative survey of 1265 LHTDs at 32 truck stops across the contiguous United States in 2010. Data were collected on truck crashes, near misses, moving violations, work-related injuries, work environment, safety climate, driver training, job satisfaction, and driving behaviors. Results suggested that an estimated 2.6% of LHTDs reported a truck crash in 2010, 35% reported at least one crash while working as an LHTD, 24% reported at least one near miss in the previous 7 days, 17% reported at least one moving violation ticket and 4.7% reported a non-crash injury involving days away from work in the previous 12 months. The majority (68%) of non-crash injuries among company drivers were not reported to employers. An estimate of 73% of LHTDs (16% often and 58% sometimes) perceived their delivery schedules unrealistically tight; 24% often continued driving despite fatigue, bad weather, or heavy traffic because they needed to deliver or pick up a load at a given time; 4.5% often drove 10 miles per hours or more over the speed limit; 6.0% never wore a seatbelt; 36% were often frustrated by other drivers on the road; 35% often had to wait for access to a loading dock; 37% reported being noncompliant with hours-of-service rules (10% often and 27% sometimes); 38% of LHTDs perceived their entry-level training inadequate; and 15% did not feel that safety of workers was a high priority with their management. This survey brings to light a number of important safety issues for further research and interventions, e.g., high prevalence of truck crashes, injury underreporting, unrealistically tight delivery schedules, noncompliance with hours-of-service rules, and inadequate entry-level training.  相似文献   
8.
The article presents the results of an assessment of the hydromorphological state of selected Carpathian rivers in sections above and below the reservoirs. An attempt has also been made to assess the impact of reservoirs on the hydromorphological conditions and quality of river habitats. The research was based on the River Habitat Survey (RHS) method. The synthetic indices Habitat Quality Assessment (HQA) and Habitat Modification Score (HMS) were calculated on the basis of the gathered data for each section studied; this allowed the hydromorphological qualities of the rivers to be assessed numerically. The reservoirs interrupt river continuum, and they alter different biotic and abiotic elements of natural environment. However, this study has shown that the operation of reservoirs does not always negatively impact the hydromorphological conditions of rivers that reflect their habitat quality. The influence of reservoirs on a river's hydromorphological state above and below a reservoir's location may be neutral, but it also can improve the habitat conditions of a river.  相似文献   
9.
This analysis has been conducted to explore the validity and reliability of the Food Choice Questionnaire (FCQ) across 9 European countries. Variation in the factor structure and the perceived importance of food choice motives have been compared cross-nationally. Volunteers (N = 9381) were recruited from an existing panel of a social research agency to take part in the Food4Me survey in Germany, Greece, Ireland, Poland, Portugal, Spain, the Netherlands, the UK and Norway. The survey was administered on-line. Configural, metric and scalar invariance fell within acceptable limits and were consistent across the 9 countries. All reliability parameters were above acceptable levels. Factor analysis confirmed that all items loaded onto the same 9 factors established by Steptoe and Pollard (1995). There was highly significant agreement in the relative importance of food choice factors between countries. Price was ranked as most important food choice factor in five countries (Spain, Greece, Ireland, Portugal and the Netherlands), sensory appeal was ranked first for three countries (Norway, Germany and the UK) while natural content was ranked as the most important factor in Poland. Familiarity and ethical concern were consistently ranked as least important in all countries. These data suggest that the FCQ is a suitable tool for exploring food choice motives across different European populations. Differences in relative importance of factors within countries may need to be taken into account in dietary health intervention and food product development.  相似文献   
10.
兰建国 《现代矿业》2020,36(7):13-16
为深入贯彻生态文明思想,促进矿产资源全面节约和高效利用,对招远市展开了金矿矿产资源开发利用水平调查评价,对2018年度数据进行整理和实地核查后,进行了单个矿山评价和多矿山评价,包括矿种评价、地区评价、行业评价。招远市16个矿山实际数据和基准值指标对比显示,单个矿山评价和多矿山评价的达标率均为100%。在此基础上,分析了金矿矿产资源资源开发利用水平调查评价的意义和存在问题。  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