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   82篇
  免费   0篇
  国内免费   1篇
安全科学   1篇
环保管理   7篇
综合类   14篇
基础理论   20篇
污染及防治   28篇
评价与监测   10篇
社会与环境   3篇
  2021年   1篇
  2018年   2篇
  2017年   1篇
  2014年   1篇
  2013年   3篇
  2012年   2篇
  2011年   6篇
  2010年   4篇
  2009年   7篇
  2008年   9篇
  2007年   8篇
  2006年   4篇
  2005年   5篇
  2004年   1篇
  2003年   2篇
  2002年   2篇
  2001年   1篇
  2000年   3篇
  1997年   1篇
  1995年   1篇
  1994年   3篇
  1992年   1篇
  1991年   1篇
  1990年   1篇
  1983年   1篇
  1982年   1篇
  1979年   2篇
  1978年   2篇
  1977年   1篇
  1974年   1篇
  1973年   1篇
  1961年   1篇
  1960年   1篇
  1954年   1篇
  1946年   1篇
排序方式: 共有83条查询结果,搜索用时 16 毫秒
71.

Introduction  

Meristematic mitotic cells of Allium cepa constitute an adequate material for cytotoxicity and genotoxicity evaluation of environmental pollutants, such as phenol, which is a contaminant frequently found in several industrial effluents.  相似文献   
72.

Background, aim, and scope  

Biowaste contains compounds of agricultural value such as organic carbon, nutrients, and trace elements and can partially replace mineral fertilizer (MIN) and improve the physical properties of the soil. However, the obvious benefits of land spreading need to be carefully evaluated against potential adverse effects on the environment and human health. Environmental contamination resulting from biowaste application is one of the key variables when assessing cost/benefits. This study provides data on the resulting concentration of polychlorinated dibenzodioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) in the soil column as a result of the different types of fertilizers.  相似文献   
73.
In order to assess whether nitrogen (N) loads in mosses reflect different land uses, 143 sites in North Rhine-Westphalia, the Weser-Ems Region and the Euro Region Nissa were sampled between 2000 and 2005. The data were analysed statistically with available surface information on land use and forest conditions. N bioaccumulation in mosses in the Weser-Ems Region with high densities of agricultural land use and livestock exceeded the concentrations in the more industrialised Euro Region Nissa. In all three study areas agricultural and livestock spatial densities were found to be positively correlated with N bioaccumulation in mosses. In North Rhine-Westphalia, the N concentrations in mosses was also moderately correlated with N concentrations in leaves and needles of forest trees. The moss method proved useful to assess the spatial patterns of N bioaccumulation due to land use.  相似文献   
74.
75.

Goal and Scope

The coastal zones of Lower Saxony (Germany) are former malaria regions. Malaria had finally become extinct in the early 1950s, and subsequently related scientific investigations declined. But from that time until nowadays, the vector in the form of Anopheles mosquitoes has still been present in Lower Saxony. Thus, the question arises, whether a new autochthon transmission could take place due to the monthly mean temperatures of the recent years. Answering this question was one goal of the investigation at hand. Another one was to examine the spatial and temporal structure of potential transmissions in respect to the predicted increase of the air temperatures according to the IPCC scenarios.

Methods

Current information about anophelines and their characteristics within Germany, such as details on historical incidences, breeding preferences, longevity or distribution of the respective species, were collected by literature research. Further, measurement and incidence data had to be collected and processed: temperature values were provided by the Deutscher Wetterdienst (DWD), and recent findings of Anopheles were supplied by the former Niedersächsisches Landesamt für Ökologie (NLÖ) as a data bank. Then temperature maps were calculated for the three periods (1947–1960, 1961–1990, 1985–2004) by means of Kriging. To model areas at risk, the transmission potential for a new vivax malaria spread in respect to temperature was computed using the Basic Reproduction Rate (R0) formula. It provides the average number of secondary infections produced when a single infected individual is introduced into a potential host population in which each member is susceptible.

Results

The computations corroborate a climate warming between the 30-years interval from 1961 to 1990 and the period from 1985 to 2004. According to the rise of the air temperature as predicted by the IPCC scenarios, the spatial pattern of potential malaria outbreak was calculated for 2020, 2060 an 2100. To this end, for each of these years a best-case-scenario with the lowest reasonable temperature increases (+0.3°C, +0.9°C, +1.4°C) and a worst-case-scenario implying the highest plausible temperature rise (+0.9°C, +3.3°C, +5.8°C) were assumed. While in 2020 the maximum duration of the transmission risk is estimated to last four months, in 2100 the vivax transmission will be likely from May until October.

Discussion

Correlated with the higher monthly mean temperature values, the risk of a vivax transmission is increasing as temperature is the determining variable of the mathematical model. Therefore Lower Saxony is at risk of a new outbreak of vivax malaria assuming no other risk factors are of relevance.

Conclusions

The study could demonstrate that most parts of the country lie within a transmission zone with a duration of two months. The areas containing the highest risk with a transmission length of three months are located around Nordhorn and Hameln, and within the rectangle of Celle, Hannover, Helmstedt and Wolfsburg. These areas match with recent Anopheles larvae finding by the NLÖ, thus, only the pathogen is lacking for a successful transmission. And as Germany is not an endemic malaria zone, the pathogen can enter the country most likely by infected people or imported mosquitoes that transport it in their guts.

Recommendations and Perspectives

The results should be understood as a request for more comprehensive investigations in that field. This would be an essential basis for a successful risk monitoring and precautionary management. Although the chances of a new endemic malaria disease in Germany seem to be considerably low today, it would be better to be prepared than to be suddenly faced with the unexpected.  相似文献   
76.
77.
78.
Integrative (interdisciplinary and transdisciplinary) landscape research projects are becoming increasingly common. As a result, researchers are spending a larger proportion of their professional careers doing integrative work, participating in shifting interdisciplinary teams, and cooperating directly with non-academic participants. Despite the growing importance of integrative research, few studies have investigated researchers’ experiences in these projects. How do researchers perceive the outcomes of integrative projects, or career effects? Do they view the projects generally as successes or failures? This study analyses researchers’ experiences in integrative landscape studies and investigates what factors shape these experiences. The data stems from 19 semi-structured qualitative interviews and a Web-based survey among 207 participants in integrative landscape research projects. It finds that researchers experience participation in integrative projects as positive, in particular discussions among participants, networking, teamwork, and gaining new insights and skills. Furthermore, most researchers perceive the projects as successful and as having a positive effect on their careers. Less positive aspects of integration relate to publications and merit points. Factors found to contribute to positive experiences include reaching a high degree of integration amongst the involved disciplines, common definitions of integrative research concepts, and projects that include a large share of fundamental research as well as projects with many project outcomes. Based on these findings, we advise future projects to plan for integration, facilitate discussions, and reach agreement on integrative concepts. We suggest that aspects of fundamental research be included in integrative projects. We also suggest that planning be done at an early stage for peer-reviewed publications, to ensure that participants gain merit points from their participation in integrative research efforts.  相似文献   
79.
Although dominant African wild dogs (Lycaon pictus) are generally believed to be the sole breeders within a pack, earlier behavioral and endocrine data suggest that reproduction could be shared with subordinates. We performed an extensive behavioral, demographic, and genetic evaluation of a wild dog population in South Africa to examine the level of such sharing and the proximate mechanisms influencing reproductive contributions of each sex. While a majority of pups were born to dominants because of a lack of subordinate potential breeders, we discovered a substantial portion of reproductive sharing between dominants and subordinates. Compared with alpha females that mated annually, subordinate beta females bred in 54.5% of years whereas thetas never bred. The three top-ranking males all sired pups (56.0%, 32.0%, and 12.0%, respectively) when three or more adult males were present. With only two pack males, alpha and beta individuals shared reproduction nearly equally (55.2% and 44.8%, respectively), and litters of mixed paternity were discovered on eight of 15 (53.3%) occasions. A skewed adult sex-ratio and frequent alpha mortalities for females and behavioral aggression in males allowed most individuals to attain dominant status in their lifetime, creating a constantly shifting social hierarchy. Genetic parentage results corresponded to reported hormone profiles, suggesting physiological suppression in some lower-ranked individuals of both sexes. Thus, a combination of demographic, behavioral, and hormonal proximate factors mediates reproductive partitioning in wild dogs. We conclude that reproductive sharing can be significant in this species, especially for males that have less robust suppressive mechanisms than females.  相似文献   
80.
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