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   591篇
  免费   8篇
  国内免费   3篇
安全科学   8篇
废物处理   16篇
环保管理   70篇
综合类   141篇
基础理论   115篇
污染及防治   199篇
评价与监测   41篇
社会与环境   11篇
灾害及防治   1篇
  2021年   10篇
  2020年   4篇
  2019年   4篇
  2018年   20篇
  2017年   13篇
  2016年   12篇
  2015年   6篇
  2014年   14篇
  2013年   34篇
  2012年   19篇
  2011年   25篇
  2010年   14篇
  2009年   20篇
  2008年   32篇
  2007年   35篇
  2006年   20篇
  2005年   26篇
  2004年   14篇
  2003年   15篇
  2002年   22篇
  2001年   16篇
  2000年   14篇
  1999年   7篇
  1998年   4篇
  1997年   9篇
  1996年   19篇
  1995年   14篇
  1994年   8篇
  1991年   4篇
  1988年   5篇
  1987年   4篇
  1986年   6篇
  1984年   4篇
  1983年   4篇
  1982年   6篇
  1981年   5篇
  1980年   3篇
  1978年   8篇
  1977年   4篇
  1976年   5篇
  1973年   3篇
  1972年   4篇
  1968年   4篇
  1964年   3篇
  1960年   5篇
  1957年   4篇
  1956年   3篇
  1955年   8篇
  1954年   4篇
  1939年   5篇
排序方式: 共有602条查询结果,搜索用时 31 毫秒
61.
62.
63.
Neonatal hemochromatosis (NH) is a rare disorder but the most common cause of acute liver failure in neonates. NH is characterized by severe hepatic injury and iron overload and is associated with high perinatal mortality and morbidity rates. NH is often preceded by oligohydramnios and intrauterine growth restriction, suggesting an important impact of NH during fetal life. Stillbirth and prematurity are not uncommon. During the last decade, major discoveries on the etiology of NH have radically changed the management and outcome of this disease. NH is now regarded as an alloimmune disease and is, as such, often referred to as gestational alloimmune liver disease. Antenatal treatment with intravenous immunoglobulins starting at 14 weeks' gestation has been shown to prevent the development of NH in subsequent pregnancies. Postnatal treatment, previously based on the use of anti-oxidants and chelation therapy, has now successfully been replaced by exchange transfusions and intravenous immunoglobulins substitution. This review summarizes the latest discoveries on the etiology of NH and the new recommendations concerning its management and prevention. © 2013 John Wiley & Sons, Ltd.  相似文献   
64.
65.
Coastal catchments in British Columbia, Canada, experience a complex mixture of rainfall‐ and snowmelt‐driven contributions to flood events. Few operational flood‐forecast models are available in the region. Here, we integrated a number of proven technologies in a novel way to produce a super‐ensemble forecast system for the Englishman River, a flood‐prone stream on Vancouver Island. This three‐day‐ahead modeling system utilizes up to 42 numerical weather prediction model outputs from the North American Ensemble Forecast System, combined with six artificial neural network‐based streamflow models representing various slightly different system conceptualizations, all of which were trained exclusively on historical high‐flow data. As such, the system combines relatively low model development times and costs with the generation of fully probabilistic forecasts reflecting uncertainty in the simulation of both atmospheric and terrestrial hydrologic dynamics. Results from operational testing by British Columbia's flood forecasting agency during the 2013‐2014 storm season suggest that the prediction system is operationally useful and robust.  相似文献   
66.
The Gold Coast City is the tourist center of Australia and has undergone rapid and massive urban expansion over the past few decades. The Broadwater estuary, in the heart of the City, not only offers an array of ecosystems services for many important aquatic wildlife species, but also supports the livelihood and lifestyles of residents. Not surprisingly, there have been signs of imbalance between these two major services. This study combined a waterway hydraulic and pollutant transport model to simulate diffuse nutrient and sediment loads under past and future proposed land-use changes. A series of catchment restoration initiatives were modeled in an attempt to define optimal catchment scale restoration efforts necessary to protect and enhance the City’s waterways. The modeling revealed that for future proposed development, a business as usual approach to catchment management will not reduce nutrient and sediment loading sufficiently to protect the community values. Considerable restoration of upper catchment tributaries is imperative, combined with treatment of stormwater flow from intensively developed sub-catchment areas. Collectively, initiatives undertaken by regulatory authorities to date have successfully reduced nutrient and sediment loading reaching adjoining waterways, although these programs have been ad hoc without strategic systematic planning and vision. Future conservation requires integration of multidisciplinary science and proactive management driven by the high ecological, economical, and community values placed on the City’s waterways. Long-term catchment restoration and conservation planning requires an extensive budget (including political and societal support) to handle ongoing maintenance issues associated with scale of restoration determined here.  相似文献   
67.
Human influence associated with land use may cause considerable biodiversity losses, namely in oceanic islands such as the Azores. Our goal was to identify plant indicator species across two gradients of increasing anthropogenic influence and management (arborescent and herbaceous communities) and determine similarity between plant communities of uncategorized vegetation plots to those in reference gradients using metrics derived from R programming. We intend to test and provide an expedient way to determine the conservation value of a given uncategorized vegetation plot based on the number of native, endemic, introduced, and invasive indicator species present. Using the metric IndVal, plant taxa with a significant indicator value for each community type in the two anthropogenic gradients were determined. A new metric, ComVal, was developed to assess the similarity of an uncategorized vegetation plot toward a reference community type, based on (i) the percentage of pre-defined indicator species from reference communities present in the vegetation plots, and (ii) the percentage of indicator species, specific to a given reference community type, present in the vegetation plot. Using a data resampling approach, the communities were randomly used as training or validation sets to classify vegetation plots based on ComVal. The percentage match with reference community types ranged from 77 to 100 % and from 79 to 100 %, for herbaceous and arborescent vegetation plots, respectively. Both IndVal and ComVal are part of a suite of useful tools characterizing plant communities and plant community change along gradients of anthropogenic influence without a priori knowledge of their biology and ecology.  相似文献   
68.
69.
70.
As a result of climate changes, more land is now needed in the Netherlands for water retention in towns and the countryside. Recently, this perceived need has resulted in new forms of water management and spatial planning strategies. Multi-functional land use is an option such as housing in combination with retention lakes. Some argue that the market potential is high and that water has an added value in residential environments. This added value could be used to compensate for non-profitable investments such as the creation of lakes. The key question is how to value this amenity. It is argued that non-economists often assume that a valuation is just a technique. The authors challenge this by presenting an overview of economic perspectives as well as techniques. A literature review reveals the main valuation perspectives and suggests estimated added values of 10‐15% for the seashore, 5‐10% for river locations (streams), and 5% for lakes.  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