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   1028篇
  免费   112篇
  国内免费   26篇
电工技术   80篇
综合类   65篇
化学工业   60篇
金属工艺   31篇
机械仪表   33篇
建筑科学   131篇
矿业工程   25篇
能源动力   26篇
轻工业   89篇
水利工程   15篇
石油天然气   13篇
武器工业   1篇
无线电   175篇
一般工业技术   125篇
冶金工业   57篇
原子能技术   2篇
自动化技术   238篇
  2025年   2篇
  2024年   18篇
  2023年   24篇
  2022年   29篇
  2021年   35篇
  2020年   35篇
  2019年   27篇
  2018年   30篇
  2017年   30篇
  2016年   34篇
  2015年   33篇
  2014年   70篇
  2013年   62篇
  2012年   90篇
  2011年   85篇
  2010年   62篇
  2009年   70篇
  2008年   52篇
  2007年   74篇
  2006年   47篇
  2005年   33篇
  2004年   33篇
  2003年   38篇
  2002年   44篇
  2001年   18篇
  2000年   23篇
  1999年   10篇
  1998年   5篇
  1997年   8篇
  1996年   2篇
  1995年   8篇
  1994年   2篇
  1993年   4篇
  1992年   4篇
  1991年   1篇
  1988年   2篇
  1987年   1篇
  1980年   1篇
  1968年   1篇
  1967年   1篇
  1965年   1篇
  1964年   1篇
  1963年   1篇
  1962年   1篇
  1961年   3篇
  1960年   3篇
  1959年   3篇
  1958年   1篇
  1956年   3篇
  1955年   1篇
排序方式: 共有1166条查询结果,搜索用时 15 毫秒
1.
阐述了质量体系认证与产品质量的关系,指出了不能将质量体系认证等同于对产品质量的评定。作者同时指出了质量体系认证对产品质量提高的重大促进作用,企业在进行质量体系认证时应把产品质量情况作为一项重要的考查内容。  相似文献   
2.
对索氏抽提法测定含油量的方法进行了改良,在原索氏抽提装置上加装了恒温冷凝水系统,将冷凝水温度改为恒温15℃。改良后的索氏抽提法与原方法相比,测定结果的准确度和灵敏度显著提高,有效消除了因季节、气候等因素引起的温度变化所带来的测定值差异。2007年至2010年加拿大谷物委员会组织36家国际权威油料检测实验室开展国际油料品质比对检测,结果显示,本实验室检测结果|Z|值均小于2,且采用改良索氏抽提法后,测定结果的Z比分数由-1.98~-0.12减小到-0.60~0.20,相对偏差由-2.5%~-0.38%减小到-1.24%~0.24%,实现了含油量检测结果的国际接轨。  相似文献   
3.
Our objective was to evaluate how sampling strategies (i.e., how many cows to sample and which animals to include) used in 4 dairy cattle welfare assessment programs affect the classification of dairy farms relative to thresholds of acceptability for animal-based measures. We predicted that classification performance would improve when more cows were sampled and when selecting from all lactating cows versus when some pens were excluded. On 38 freestall farms, we assessed all 12,375 cows for lameness, injuries on the tarsal (hock) and carpal joints, and body condition score and calculated the farm-level prevalence for each measure. Based on approaches used in the industry, we evaluated 6 sampling strategies generated using formulas with precision (d) of 15, 10, or 5% applied to either a single high-producing pen or all lactating cows; an additional sample was included with d = 10% applied to the entire herd, selecting lactating cows in proportion to their representation in the herd. For each sampling strategy, cow records were selected randomly (in 10,000 replicates) to calculate prevalence. The strategy of assessing all cows in the high-producing pen was also compared. Farms were classified as meeting (below) or failing to meet (above) thresholds of ≤15% moderate lameness; ≤20% moderate carpal or hock injuries; <10, <5, and ≤1% severe lameness; or injuries on the carpus or hock; and <5, <3, <1, or 0% thin cows. For each measure and threshold, we calculated pooled percent agreement, kappa, sensitivity, specificity, and positive and negative predictive value for each sampling strategy using true prevalence as the gold standard for herd classification. Across measures and thresholds, classification performance increased with the number of cows sampled [i.e., when narrower precision values (d = 5 vs. 10 vs. 15%) were used in the sample size calculation]. Because narrower precision values can dramatically increase sample size, assessment programs may need to consider both feasibility and the degree of misclassification they will accept. Applying the formula directly to lactating cows performed better than applying it to the entire herd and then selecting lactating cows in proportion to their representation in the herd. Farm classifications were similar whether cows in the hospital pen were included or excluded from the sample. Selecting all cows from the high-producing pen resulted in classifications similar to when including all lactating cows, suggesting that assessing cows from the high-producing pen may serve as an acceptable proxy for all lactating cows on the farm.  相似文献   
4.
系统介绍了与食品相关的认证体系和产品认证等最新知识,特别介绍了当前比较热门的一些认证形式及其在食品产业尤其是在农产品生产与加工中的应用。  相似文献   
5.
OBJECTIVE: To describe the development and preliminary results from a community based certification model for training in tobacco cessation skills in Arizona. DESIGN: A programme evaluation using both quantitative pre-post measures and qualitative methods. SETTING: Arizona's comprehensive tobacco control programme of state funded, community based local projects and their community partners providing tobacco treatment services for geographically, socioeconomically, and ethnically diverse communities. INTERVENTION: A three tiered model of skills based training emphasising Agency for Health Care Policy and Research guidelines, and utilising a training of trainers approach to build community capacity. Certification roles addressed basic tobacco cessation skills, tobacco cessation specialist, and tobacco treatment services manager. PARTICIPANTS: Initial target audience was community based local project personnel and their community partners, with later adoption by community organisations unaffiliated with local projects, and the general public. MAIN EVALUATION MEASURES: Process measures: participant satisfaction, knowledge, skills, and self-efficacy. Outcome: participant demographics, community organisations represented, post-training, cessation related activities. RESULTS: During the model's implementation year, 1075 participants attended certification training, 947 participants received basic skills certificates and 82 received specialist certificates. Pre, post, and three month measures of self efficacy showed significant and durable increases. Analysis of participant characteristics demonstrated broad community representation. At post-training follow up, 80.9% of basic skills trainees had performed at least one brief intervention and 74.8% had made a referral to intensive services. Among cessation specialists, 48.8% were delivering intensive services and 69.5% were teaching basic skills classes. CONCLUSIONS: Initial experience with Arizona's state wide, community based model for certification of tobacco cessation skills training suggests this model may be a promising method for broad, population based diffusion of evidence based tobacco cessation guidelines.  相似文献   
6.
根据我国农产品认证的特点,具体阐述农产品认证对农产品质量安全的影响与推动作用,说明了通过农产品认证对建立集约化生产组织体系、推广农产品标准化生产、建立农产品追溯体系及转变农产品生产模式的促进作用,论述了通过提升农产品质量管理水平来促进农业生产和农产品质量安全的全面提升。  相似文献   
7.
在农村,集体土地所有权登记发放证的数据建库对于农民具有十分重要的影响,因此建库人员应该熟练掌握数据建库的技术,并且在建库的过程中注意建库的几个关键的问题,这样才能够做好农村集体土地所有权登记发证的数据建库工作。  相似文献   
8.
席会明 《化工设计》1998,8(2):45-46
针对设计系统贯标认证的情况,阐述质量体系要求和产品要求的区别以及质量体系认证和产品质量的关系;提出解决贯标认证与产品质量相脱节的措施。  相似文献   
9.
近年来,伴随着全球由“工业经济”向“服务经济”转型,以及服务贸易的迅速发展,服务认证作为一种保证服务质量,促进服务业和服务贸易发展的重要手段已被世界上越来越多的国家和地区接受,成为国际惯例。文章从分析国际、国内服务认证发展现状入手,在此基础上提出了我国开展服务认证的建议。  相似文献   
10.
GB12350《小功率电动机安全要求》新旧版本的转换,对电机行业将造成极大的影响。本文主要通过分析此次GB12350《小功率电动机安全要求》换版对福建省电机行业造成的影响及存在问题,并针对具体存在问题提出建议,帮助福建省电机行业顺利完成新旧标准的转换。  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