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   303篇
  免费   0篇
  国内免费   2篇
安全科学   5篇
废物处理   7篇
环保管理   15篇
综合类   195篇
基础理论   28篇
污染及防治   37篇
评价与监测   6篇
社会与环境   12篇
  2022年   5篇
  2018年   9篇
  2015年   6篇
  2013年   8篇
  2012年   4篇
  2010年   7篇
  2009年   6篇
  2008年   9篇
  2007年   6篇
  2006年   6篇
  2005年   4篇
  2004年   4篇
  2003年   3篇
  2002年   6篇
  2000年   4篇
  1999年   7篇
  1998年   6篇
  1994年   3篇
  1992年   5篇
  1985年   3篇
  1983年   3篇
  1982年   3篇
  1967年   3篇
  1963年   5篇
  1962年   8篇
  1961年   4篇
  1960年   6篇
  1959年   3篇
  1958年   9篇
  1957年   12篇
  1956年   13篇
  1955年   17篇
  1954年   6篇
  1953年   6篇
  1952年   4篇
  1950年   5篇
  1941年   2篇
  1939年   4篇
  1938年   4篇
  1937年   3篇
  1936年   2篇
  1935年   5篇
  1933年   2篇
  1931年   3篇
  1930年   5篇
  1929年   3篇
  1924年   2篇
  1922年   2篇
  1920年   2篇
  1913年   3篇
排序方式: 共有305条查询结果,搜索用时 312 毫秒
181.
Summary The biology and behavior of Xylocopa virginica L. were followed in the area of Athens, Georgia (USA) from August 1973 until September 1974. Several nests were X-rayed regularly during the developmental period of the bees, and information about the life cycle and development was obtained. The bees emerge in June and stay in their nests with their sibs throughout the summer, fall, and winter, leaving only occasionally on warm days to search for nectar as food. In March and April males defend nest-side territories and mate with most females. The males die in the late spring and the females dig nests, provision them, and rear up to 8 or 9 bees in each nest. Many females live 2 years, and often 2 to 3 females are present in each nest, but only 1 works and lays eggs. Emergence of adults from pupae is nearly synchronized, irrespective of age.  相似文献   
182.
183.
184.
185.
实验室老化设备   总被引:3,自引:0,他引:3  
RudyLeber 《环境技术》2002,20(1):9-16
介绍人工老化试验设备中最常用的几种光源的产生、发展、结构和特点,并从与自然光源相似程度的角度,分析了几种光源的优缺点。  相似文献   
186.
Olfactory learning may occur at different stages of insect ontogeny. In parasitoid wasps, it has been mostly shown at adult emergence, whilst it remains controversial at pre-imaginal stages. We followed larval growth of the parasitoid wasp, Aphidius ervi Haliday, inside the host aphid, Acyrthosiphom pisum Harris, and characterised in detail the behaviour of third instar larvae. We found that just before cocoon spinning begins, the third instar larva bites a hole through the ventral side of the mummified aphid exoskeleton. We then evaluated whether this period of exposure to the external environment represented a sensitive stage for olfactory learning. In our first experiment, the third instar larvae were allowed to spin their cocoon on the host plant (Vicia faba L.) surface or on a plastic plate covering the portion of the host plant exposed to the ventral opening. Recently emerged adults of the first group showed a preference for plant volatiles in a glass Y-olfactometer, whereas no preference was found in adults of the second group. In a second experiment, during the period in which the aphid carcass remains open or is being sealed by cocoon spinning, third instar larvae were exposed for 24 h to either vanilla odours or water vapours as control. In this experiment, half of the parasitoid larvae were later excised from the mummy to avoid further exposure to vanilla. Adult parasitoids exposed to vanilla during the larval ventral opening of the mummy showed a significant preference for vanilla odours in the olfactometer, regardless of excision from the mummy. The larval behaviour described and the results of the manipulations performed are discussed as evidences for the acquisition of olfactory memory during the larval stage and its persistence through metamorphosis.  相似文献   
187.
188.
The aim of the Bavarian Monitoring of Breast Milk (BAMBI) project was to examine 10 organochlorine pesticides (OPs), 3 nitro musks, 6 indicator polychlorinated biphenyls (PCBs), 7 polychlorinated dibenzo-p-dioxins (PCDDs), 10 polychlorinated dibenzofurans (PCDFs), 12 dioxin-like PCBs (dl-PCBs) and several perfluorinated alkyl compounds in breast milk samples. A total of 516 breast milk samples were collected from seven regions in Bavaria and were analyzed by means of GC/ECD, GC/HRMS, and LC/MS-MS.  相似文献   
189.
INTRODUCTION: Overexposure to noise remains a widespread and serious health hazard in the U.S. service providing and goods producing industries. Excessive noise can lead to poor verbal communication and reduce the ability to recognize warning signals. These dangerous work conditions can also cause stress and fatigue. Occupational hearing loss is a permanent illness, with no recovery currently possible. METHOD: National Institute for Occupational Safety and Health (NIOSH) has recognized Noise Induced Hearing Loss (NIHL) as one of the ten leading work-related diseases and injuries in the United States, and has emphasized its importance as one of the critical areas expressed in the National Occupational Research Agenda. RESULTS: One of the most serious noise problems in the goods producing industries is the operation of continuous mining machines during underground coal mining. In order to minimize occupational hearing loss, noise hazards are "designed out" early in the design process. NIOSH is leading a national initiative called Prevention through Design (PTD) to promote this concept. This paper describes the quiet-by-design approach of a noise control that reduced noise exposures of continuous mining machine operators by 3dB(A) using the four functional areas of PTD, namely Practice, Policy, Research, and Education.  相似文献   
190.
Regional Environmental Change - This article describes the design of a new model-based assessment framework to identify and analyse possible future trajectories of agricultural development and...  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