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   479篇
  免费   4篇
  国内免费   12篇
安全科学   29篇
废物处理   18篇
环保管理   96篇
综合类   59篇
基础理论   96篇
污染及防治   125篇
评价与监测   42篇
社会与环境   27篇
灾害及防治   3篇
  2023年   5篇
  2022年   12篇
  2021年   15篇
  2020年   6篇
  2018年   10篇
  2017年   10篇
  2016年   15篇
  2015年   11篇
  2014年   14篇
  2013年   49篇
  2012年   10篇
  2011年   24篇
  2010年   19篇
  2009年   20篇
  2008年   21篇
  2007年   23篇
  2006年   19篇
  2005年   11篇
  2004年   19篇
  2003年   17篇
  2002年   19篇
  2001年   8篇
  2000年   5篇
  1999年   4篇
  1998年   10篇
  1997年   10篇
  1996年   8篇
  1995年   4篇
  1993年   9篇
  1992年   7篇
  1991年   6篇
  1990年   4篇
  1989年   3篇
  1987年   3篇
  1985年   5篇
  1984年   5篇
  1983年   2篇
  1982年   4篇
  1981年   3篇
  1979年   4篇
  1978年   2篇
  1977年   2篇
  1975年   3篇
  1973年   2篇
  1964年   2篇
  1963年   2篇
  1958年   2篇
  1957年   2篇
  1956年   3篇
  1955年   3篇
排序方式: 共有495条查询结果,搜索用时 15 毫秒
181.
In the area of end-of-life vehicle (ELV) recycling, Japan passed the Automobile Recycling Law in January 2005, the first in Asia. Korea followed suit with the passage of the resource circulation method in 2009. China is expected make a new recycling law in 2011. In contribution to these initiatives, Tohoku University made a comparative analysis of ELV recycling laws, advance dismantling experiments and scenario analysis to promote international cooperation. This is envisioned to introduce ELV recycling system in Japan, China and Korea and in developing countries as well.  相似文献   
182.
Environmental Science and Pollution Research - The COVID-19 pandemic has created unprecedented human health crisis in recent global history with rippling social and economic effects. The outbreak...  相似文献   
183.
Journal of Material Cycles and Waste Management - The application of waste materials based fillers is unique way to achieve rubber composites, which reduces the amount of waste in the environment...  相似文献   
184.
185.
Surveys of juvenile hawksbills around Buck Island Reef National Monument, US Virgin Islands from 1994 to 1999 revealed distributional patterns and resulted in a total of 75 individual hawksbill captures from all years; turtles ranged from 23.2 to 77.7 cm curved carapace length (CCL; mean 42.1 ± 12.3 cm SD). Juveniles concentrated where Zoanthid cover was highest. Length of time between recaptures, or presumed minimum site residency, ranged from 59 to 1,396 days (mean 620.8 ± 402.4 days SD). Growth rates for 23 juveniles ranged from 0.0 to 9.5 cm year?1 (mean 4.1 ± 2.4 cm year?1SD). Annual mean growth rates were non-monotonic, with the largest mean growth rate occurring in the 30–39 cm CCL size class. Gastric lavages indicated that Zoanthids were the primary food source for hawksbills. These results contribute to our understanding of juvenile hawksbill ecology and serve as a baseline for future studies or inventories of hawksbills in the Caribbean.  相似文献   
186.
In the past few decades, the tourism sector has emerged as a significant economic activity in island nations, particularly in tropical regions. However, most of the tropical islands face similar constraints, viz., threat to natural resources, chances of biopiracy, impact of climate change, population pressure and unsystematic tourist management. Ecotourism, as a concept, envisages promoting tourism with due regard to natural environment and ecological sanctity of the destination. Archipelago of Andaman and Nicobar (A&N) Islands is one of picturesque geographical creation in the Bay of Bengal, India, in tropical region and is an emerging tourist destination. It was observed that around 2.2 lakhs national and international tourists visit the A&N Islands annually. With tourism sector as an integral component, the service sector with share of 56% in gross state domestic product dominates the island economy. An analysis based on primary survey from various stakeholders associated with the sector revealed that factors such as economy in travel and boarding, availability of tourist facilities and comfort, safety, etc. were major factors that determined the choice of the tourists that visited the islands. The weights given by the tourists to the natural sites in A&N Islands revealed that the landscape topped list with 91.6% score by the visitors followed by beaches (91.3%), scenery (86.5%), reserved forests (84.6%), limestone caves (66.3%) and coral sights (65.8%). Coral sites were given weight of 65.8% of tourists, cultural and historical tourism products 85.4% for the natural history. Similarly, historical sites (83.7%), museums (78.6%) and heritage sites (72.8%) were also among top cites attraction. Recent initiatives by the Andaman administration gives due to care to sustainably develop the tourism infrastructure of the islands to harness the potential of eco-friendly tourism in this picturesque tourist haven.  相似文献   
187.
Trevor Kletz has left an indelible mark on worldwide chemical process safety. He generously shared his insight for decades and I have been fortunate to have spent my process safety career in the shadow of Trevor Kletz’s influence. In the early 1980s I purchased one of the first commercially available process safety awareness training modules. The module was entitled the “Hazards of Over and Under Pressurizing Tanks,” developed by Trevor, and distributed by the Institution of Chemical Engineers (IChemE). The module contained a collection of short case histories and each incident provided a message on fundamentals. It was an easy to use module with a couple of dozen vivid 35 mm slides and focused on the frail nature of tanks.This paper, “Tanks A Lot – Trevor” mimics the IChemE approach of three decades ago and could serve as an introductory awareness lesson for the newbie or trainee who desires to learn about the frail nature of tanks. But most likely, it will serve as a reminder to the seasoned reader of things he or she has previously seen or worse yet, experienced.Storage tanks in chemical plants, oil refineries, related distribution terminals and pressure vessels associated in these industries are vital components and a major investment within their facilities. These essential vessels come in all sizes and many shapes and are built to various codes. They may hold large inventories of hazardous materials.Tanks can and do very safely contain a wide variety of raw materials, intermediates and finished products for years. If the tank or its accessories are poorly designed, abused by operations or are neglected with respect to effective inspection and basic maintenance, bad things can happen.This paper includes a few tank system fundamentals as well as case histories of failures in design, operation, inspection and maintenance. Previous vessel incidents must be understood.  相似文献   
188.
Conservation and management of Sundarban mangrove forest is difficult chiefly due to inaccessibility and hostile condition. Remote sensing serves as an important tool to provide up-to date baseline information which is the primary requirement for the conservation planning of mangroves. In this study, supervised classification by maximum likelihood classifier (MLC) has been used to classify LANDSAT TM and LANDSAT ETM satellite data. This algorithm is used for computing likelihood of unknown measurement vector belonging to unknown classes based on Bayesian equation. Image spectra for various mangrove species were also generated from hyperspectral image. During field visits, GPS locations of five dominant mangrove species with appreciable distribution were taken and image spectra were generated for the same points from hyperion image. The result of this classification shows that, in 1999 total mangrove forest accounted for 55.01 % of the study area which has been reduced to 50.63 % in the year 2010. Avicennia sp. is found as most dominating species followed by Excoecaria sp. and Phoenix sp. but the aerial distribution of Avicennia sp., Bruguiera sp. and Ceriops sp. has reduced. In this classification technique the overall accuracy and Kappa value for 1999 and 2010 are 80 % and 0.77, 85.71 % and 0.81 respectively.  相似文献   
189.
The Mediterranean basin has undergone widespread land cover change. Urbanization of coastal areas, land abandonment of steeper slopes, and agricultural intensification in alluvial plains are recurrent themes. The objective of this study was to examine how vineyard land cover changes have affected agricultural soil erosion in a 50 year period (1950–2011). The study area covers a 235 km2 catchment located near the Gulf of St Tropez. Aerial photographs were used to map land cover in 1950, 1982, 2003 and 2011, and the RUSLE soil erosion model was run to estimate soil erosion.

Between 1950 and 2011, vineyard went from about 2,426 ha to 1,561 ha. Mean soil erosion increased as vineyard slopes became steeper (11.8 T ha?1, 13.2 T ha?1, 14.4 T ha?1 and 13.5 T ha?1 for 1950, 1982, 2003 and 2011). Total erosion decreased after 1982: 28,621 T y?1 in 1950, 29,030 T y?1 in 1982, 22,848 T y?1 in 2003, and 21,074 T y?1 in 2011. Total soil loss in 2011 is about 75% of values in 1950–1982, so impacts on water pollution and channel dredging have evolved positively over time.  相似文献   
190.

Background

Relocations and restorations do not only change the ecological passability and sediment continuity of a river but also its flow behavior and fluvial morphodynamics. Sediment transport processes and morphological development can be assessed with field measurements, also taking the transport of sediment-bounded contaminants as a tracer material for fluvial morphodynamics into account. The objective of this study was to determine the morphological development of the Inde River (a tributary of the Rur River in North-Rhine Westphalia, Germany) towards its pre-defined guiding principle after a relocation and restoration in 2005 AD.

Methods

The fluvial morphodynamics of the Inde River were analyzed over a period of almost 15 years taking sediment samples, analyzing echo soundings of the river’s bathymetry and determining the heavy metal content of the sediment as a tracer material for the morphological development.

Results

The results show that the relocation and restoration of the Inde River initiates new hydrodynamic processes, which cause morphological changes of the river widths, meander belts and channel patterns. The riverbed of the new Inde River has incised into the ground due to massive erosion, which has led to increased fine sediment transport in the downstream direction. The reasons for and consequences of this fine sediment transport are discussed and correlated to the sediment continuity of a river.

Conclusions

Overall, the new Inde River has reached its goal of being a natural river as a consequence of the relocation and restoration and has adapted its new conditions towards a dynamic morphological equilibrium.
  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