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   214篇
  免费   22篇
  国内免费   2篇
电工技术   1篇
化学工业   32篇
金属工艺   3篇
机械仪表   2篇
建筑科学   11篇
轻工业   47篇
水利工程   3篇
无线电   7篇
一般工业技术   35篇
冶金工业   18篇
自动化技术   79篇
  2023年   6篇
  2022年   1篇
  2021年   10篇
  2020年   3篇
  2019年   6篇
  2018年   6篇
  2017年   8篇
  2016年   17篇
  2015年   13篇
  2014年   14篇
  2013年   22篇
  2012年   22篇
  2011年   19篇
  2010年   17篇
  2009年   11篇
  2008年   10篇
  2007年   4篇
  2006年   5篇
  2005年   6篇
  2004年   6篇
  2003年   6篇
  2002年   2篇
  2001年   5篇
  2000年   2篇
  1999年   6篇
  1998年   1篇
  1997年   1篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1992年   1篇
  1989年   3篇
  1981年   1篇
  1976年   1篇
排序方式: 共有238条查询结果,搜索用时 16 毫秒
1.
2.
Species distribution models have recently become important tools in ecological research. Prediction of suitable habitats for threatened and endangered species is essential for the conservation and management of their native habitats. A landscape scale approach is relevant for biodiversity conservation since landscape planning and management are generally conducted at wide spatial scales, focusing on areas with complex landscape configuration as a consequence of human activities. The aims of this study were to test a maximum entropy approach (Maxent) to the development of a niche-based model for species of conservation interest and to relate this model to landscape structure metrics. The results obtained here showed a good predictive power of Maxent for the three target species and highlighted the importance of landscape structure analysis for the detection of patterns of habitat suitability. Moreover, this work stressed that combining classical environmental information with landscape structure in analysing habitat suitability for species of conservation interest may be used to guide conservation efforts and landscape management practices.  相似文献   
3.
We have isolated a cDNA coding for a putative invertebrate-type dopamine receptor (Peadop2) from P. americana brain by using a PCR-based strategy. The mRNA is present in samples from brain and salivary glands. We analyzed the distribution of the PeaDOP2 receptor protein with specific affinity-purified polyclonal antibodies. On Western blots, PeaDOP2 was detected in protein samples from brain, subesophageal ganglion, thoracic ganglia, and salivary glands. In immunocytochemical experiments, we detected PeaDOP2 in neurons with their somata being located at the anterior edge of the medulla bilaterally innervating the optic lobes and projecting to the ventro-lateral protocerebrum. In order to determine the functional and pharmacological properties of the cloned receptor, we generated a cell line constitutively expressing PeaDOP2. Activation of PeaDOP2-expressing cells with dopamine induced an increase in intracellular cAMP. In contrast, a C-terminally truncated splice variant of this receptor did not exhibit any functional property by itself. The molecular and pharmacological characterization of the first dopamine receptor from P. americana provides the basis for forthcoming studies focusing on the significance of the dopaminergic system in cockroach behavior and physiology.  相似文献   
4.
5.
von der Lühe  Barbara  Pauli  Laura  Greenshields  Britta  Hughes  Harold J.  Tjoa  Aiyen  Sauer  Daniela 《SILICON》2021,13(12):4345-4353
Silicon - The effects of land use and fire on ecosystem silicon (Si) cycling has been largely disregarded so far. We investigated the impacts of land use and fire on Si release from topsoils and...  相似文献   
6.
Recent and past food scandals highlight the urgent need for food safety authorities to anticipate future risks in order to enable improved and proactive response mechanisms. With this goal in mind, the Bavarian Health and Food Safety Authority (LGL) has established an early warning system aimed at early identification of potential health risks and fraudulent practices in the food sector. The early warning approach allows intervention at different stages of risk development. On the one hand, the scanning of a broad area of the food production chain (horizon scanning) may enable prospective risk identification. To this end, relevant factors of influence (drivers) need to be identified, observed and analyzed. On the other hand, the retrospective analysis of case studies may unravel novel cause-effect associations that could be transferred to other products and production technologies, possibly leading to the identification of new drivers (root cause analysis). Additionally, various datasets emanating from food safety authorities, for example data from the European Rapid Alert System for Food and Feed (RASFF) and from Bavarian-wide laboratory analyses and food business inspections, will be closely observed and analyzed. The multidisciplinary character of the LGL has proven to be essential for the realization of the early warning approach, the analysis of inflowing data and implementation of consequences such as food business inspections and sampling for analysis. This article details the objectives and methodical approaches of the project. The acquisition of systematically compiled information as well as its analysis and assessment are comprehensively described. The early warning system presented here has already contributed significantly to the risk-oriented food inspection practiced to date, by integrating novel risk-relevant aspects.  相似文献   
7.
8.
9.
10.
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