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   104篇
  免费   1篇
  国内免费   7篇
教育   56篇
科学研究   18篇
体育   13篇
综合类   4篇
信息传播   21篇
  2022年   1篇
  2020年   4篇
  2018年   2篇
  2017年   1篇
  2016年   3篇
  2015年   3篇
  2014年   4篇
  2013年   8篇
  2012年   8篇
  2011年   10篇
  2010年   3篇
  2009年   11篇
  2008年   9篇
  2007年   6篇
  2006年   7篇
  2005年   4篇
  2004年   9篇
  2003年   5篇
  2002年   3篇
  2000年   4篇
  1999年   1篇
  1998年   2篇
  1997年   2篇
  1995年   1篇
  1994年   1篇
排序方式: 共有112条查询结果,搜索用时 31 毫秒
1.
氧弹灰化法快速测定有机物中的硫含量   总被引:2,自引:0,他引:2  
以氧弹燃烧法破坏有机物进行元素测定,方法简便、快捷、无污染,该法用于生物体中硫含量的测定,结果可靠。  相似文献   
2.
结合高中化学新课程的教学理念及教材编排特点,从化学教学、作业布置及非智力因素等方面阐述如何运用"最近发展区"理论。  相似文献   
3.
现有抗癌药物大部分是人工合成与半合成 ,或者是从天然植物中直接提取。细胞培养技术虽然已取得一定成功 ,但尚未能实现工业化生产。①② 而从内生真菌次生代谢产物中寻找抗癌药物的工作国内外均才开始 ,并成为一个新的热点。本文就近年来国内外对内生真菌产癌活性成分的研究进展作一综述  相似文献   
4.
研究利用数据挖掘中的关联规则挖掘分析及论文数据库,进行相关文献推荐,提出适用于进行相关文献推荐的改进的混合加权关联规则挖掘算法,并通过用户行为分析确定相关文献集和垂直权重,采用Google搜索引擎的PageRank算法确定水平权重,获得一些有意义的分析结果。  相似文献   
5.
Four standards and best practices recently released or currently underway at the National Information Standards Organization were presented: Knowledge Bases and Related Tools, Presentation and Identification of E-Journals, Open Discovery Initiative, and Open Access Metadata Indicators. Basics outlining the creation work and deliverables were shared for each project. Applicability of these standards and best practices for different stakeholders of the information community were discussed.  相似文献   
6.
《Research Policy》2022,51(9):104445
Entrepreneurial ecosystems are most often defined as locally bounded networks of institutions and individuals that help entrepreneurs to identify and exploit market opportunities. However, a prerequisite of the ability to exploit an entrepreneurial opportunity is the existence of the opportunity to begin with. In this paper, we propose an approach to representing how entrepreneurial opportunities are embedded in a regional economy. The central methodological contribution of our paper is to introduce the concept of related specialization, which we define as the concentration of high interdependencies between specialized industries within a metropolitan region, relative to the national level of concentration. We find that related specialization is positively correlated with entrepreneurial outcomes across U.S. metropolitan areas. We use related specialization to make a first attempt at representing the trophic structure of an economic ecosystem. In a biological ecosystem, the trophic structure refers to energy-transfer relationships between different species. As introduced in this paper, we propose the analogy that, in an economic ecosystem, the trophic structure may be mapped in terms of the supply-chain relationships between industries within a region. We argue that these analytic tools can help policymakers more readily understand the opportunities that are imminently available to entrepreneurs in their local environments.  相似文献   
7.
无机物的制备,首先必须考虑化学反应是否发生,然后再根据化学反应条件选择具体的制备方法,本文从理论及合成方法上对无机物的制备进行了探讨。  相似文献   
8.
对会计师事务所实施分类管理,既是一种行政手段,又是一种政策支持,更是一种经过检验正在推广的行业监督管理策略。黄冈市会计师事务所的现状是怎样的,如何划分事务所类别并进行分类监管,是每个注册会计师和会计师事务所都十分关注的。通过对黄冈会计师事务所现状、分类管理的必要性进行分析,进而对分类管理办法进行探讨。  相似文献   
9.
ABSTRACT

The Deep Dive into KBART preconference workshop provided a comprehensive overview of the National Information Standards Organization Knowledge Bases and Related Tools (KBART) Phase II Recommended Practice (http://www.niso.org/publications/rp/rp-9–2014/). The workshop was divided into four sections. The first provided an overview of the background, purpose, and value of KBART to all members of the information supply chain. The next section focused on the basic guidelines for effective exchange of metadata with knowledgebases, including method of exchange, data format, file naming conventions, and frequency of exchange. The remaining two sections of the workshop addressed the correct use of KBART data fields, first in relation to serials and then to monographs. Through classroom instruction, interactive quizzes, and hands-on exercises, the workshop provided in-depth coverage of all KBART data elements, with special focus on many of the most frequently asked questions about the recommended practice.  相似文献   
10.
关联交易中常有侵害国家、投资者、债权人利益的诸多不公平现象,须在现有《公司法》相关条款基础上尽快完善相关法律制度,建立闻联交易股东大会批准制度和信息披露制度,确立独立董事对关联交易的监督制度,改进决策制度,健全关联公司外部债权人保护制度。  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