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   179篇
  免费   0篇
  国内免费   11篇
安全科学   4篇
废物处理   9篇
环保管理   11篇
综合类   15篇
基础理论   21篇
环境理论   1篇
污染及防治   95篇
评价与监测   24篇
社会与环境   10篇
  2023年   5篇
  2022年   29篇
  2021年   24篇
  2020年   7篇
  2019年   11篇
  2018年   13篇
  2017年   14篇
  2016年   10篇
  2015年   9篇
  2014年   14篇
  2013年   14篇
  2012年   5篇
  2011年   9篇
  2010年   9篇
  2009年   2篇
  2008年   2篇
  2007年   3篇
  2004年   1篇
  2003年   1篇
  2002年   1篇
  1999年   1篇
  1990年   1篇
  1985年   2篇
  1984年   1篇
  1979年   2篇
排序方式: 共有190条查询结果,搜索用时 15 毫秒
161.
Amenity Migration and Public Lands: Rise of the Protected Areas   总被引:1,自引:0,他引:1  
Environmental Management - Rural amenity migration, or the relocation for quality of life purposes as opposed to monetary enhancement, has been occurring for decades and has been particularly...  相似文献   
162.
163.
This research letter focuses on tourist behavior and tourism business operators’ contributions to rural mountain region economic growth and sustainable development when using social media. Data were collected from 43 interviews from different tourism business operators, and a questionnaire survey of 576 tourists from the Gilgit-Baltistan, Pakistan. Drawing on development communication theory, the study reveals that there is a positive relationship between the tourists’ intentions and rural mountain region sustainable development. The study also reveals that most tourists are willing to pay more taxes when touring mountain regions. The real business outcomes from tourism business operators show that rural mountain region tourism creates better employment opportunities for the rural population. All tourists demonstrated the motivation to take part in rural mountain region sustainable development while touring rural locations. The study also offers policy implications.  相似文献   
164.
It has been repeatedly stressed that the biological effectiveness of chromium depends entirely on its oxidation state. The present work compares the histological effects of ingested trivalent and hexavalent chromium compounds on the mouse testes. The results showed comparable data of food consumption and gain in body weight. Both compounds produced ambiguous levels of degeneration in the outmost cellular layers of a number of seminiferous tubules, reduced the number of spermatogonia per tubule and the sperm count, and caused significant increases in the percentage of morphologically abnormal sperms. Generally, all these effects were more pronounced in animals which ingested the hexavalent chromium.  相似文献   
165.
Municipal solid waste management was studied for 1 year in a representative urban area of Lahore city for environmental sustainability. The effects of financial status of the household and the seasonal variations on generation rate and compositions of municipal solid waste (MSW) were determined. MSW generation rate and the economic status of the households were positively correlated (p < 0.05). Seasonal variations observed were significant only for organics (p = 0.001), plastics (p = 0.008) and food waste fractions (p = 0.009) in MSW. Response surface regression model developed and analysed by Minitab-15® showed that the interaction of season and different economic zones of the town on the MSW generation rate was non-significant (p = 0.334). Elemental and heating value analyses of the mixed organic fractions in kitchen waste had carbon 47.93%, hydrogen 6.20%, nitrogen 2.24%, sulphur 0.23%, oxygen 39.01%, and C and N ratio 27.78. Findings concluded that food waste was 56% of total MSW with 71.03% moisture content and a modest heating value of 5566 J/g. Existing temporary storage capacity of MSW is 51% of the total MSW generated considering the weighted MSW generation rate of 0.57 kg/person/day calculated in this study. Composting could be a possible final disposal option due to high moisture and organic content and can be studied in future research. Development of a transfer station, introduction of home composting programmes and awareness towards proper segregation and reduction of waste at the household level is suggested to attain sustainability in the MSW management system.  相似文献   
166.
The refraction of the 2004 Indian Ocean tsunami waves caused drastic devastation along East coast of India, mainly in the area of investigation. Here, we appraise and integrate the sedimentary characteristics and microfossil studies of the area. The gigantic tsunami waves caused the landward fining of sediments that were carried as suspended load. Tsunami sediments have distinctive characteristics, like fine-to-medium grained sand, moderately to poorly sorted sediments which indicating sudden winnowing followed by tranquil flood. Positively skewed grain size distribution indicating unidirectional transport, and mesokurtic to platykurtic character implying poorly sorted single source origin. The species of benthonic foraminifers and ostracods reside in marine environment indicating shallow water origin of sediments. The onshore deposits are vertically divided into three depositional units interpreted from Ground Penetrating Radar (GPR) signatures—Unit 1 is a relatively continuous parallel layer indicative of calm environment; Unit 2 has paleochannels and burial scarps, seen as oblique reflections that might be indicative of an intense erosional environment; Unit 3 is interpreted as 2004 tsunami layer, has three subunits. Each main units have been separated by Heavy Mineral Concentrated (HMC) layers, deposited by continuous wave action (~?20 cm) and by the tsunami (>?30 cm) activity, evidenced by low magnetic susceptibility values at the bottom compared to the top of the HMC layers. GPR has been effectively utilized in this paper as subsurface imaging tool for the interpretation and reconstruction of stratigraphy, and also helped to unearth the erosional and depositional environments.  相似文献   
167.
One of the most effective engineering measures is the provision of an exclusive motorcycle lane that separates motorcycles from other mixed traffic to reduce traffic congestion and motorcycle crashes. Even though the existing exclusive motorcycle lanes in Malaysia reduced the incidents of motorcycle crashes with other vehicles, the design of this special motorcycle lane was based on a cross reference between a bicycle track and a highway. Thus, a suitable design guide is yet to be developed for the geometrical design of a proper and safer exclusive motorcycle lane. Safe stopping sight distance (SSD) has been recognized as a criterion for road design and should be taken into account. Motorcyclist perception response time (PRT) is the time from detection object until the rider reduces motorcycle speed in braking action is an essential component of motorcycle SSD. Two road experiments were conducted to obtain empirical values of motorcycle PRT to expected and unexpected objects. In the expected condition, 89 motorcyclists applied brake as quickly as possible following activation of a light beside the road. In the unexpected condition, 16 riders responded by braking in response to an obstacle that appeared suddenly in their lane. The mean PRT to expected and unexpected object is 0.71 s and 1.25 s respectively. The 85th percentile PRT to unexpected object is 2.12 s. This study found that most riders are capable of responding to an unexpected object along the roadway in 2.5 s or less. Therefore, PRT of 2.5 s is an appropriate value for motorcycle lane geometric design.  相似文献   
168.
Acephate was incubated in distilled water of three different pH's at 37 degrees C for 7 days. Three hydrolytic products were formed: methamidophos, O,S-dimethyl phosphorothiolate (DMPT), and O-methylacetyl phosphoramidothiolate (OMPT). A single dose of acephate was also fed to mice, and their livers were excised and analyzed for metabolic products up to 30 hours. Three products were detected: methamidophos, DMPT, and S-methylacetyl phosphoramidothiolate (SMPT). The anticholinesterase properties of acephate, methamidophos, DMPT, SMPT, and OMPT were determined. Only acephate and methamidophos had measurable inhibitory effects on the mouse erythrocyte enzyme, methamidophos being about ten times more effective than acephate. The amount of methamidophos formed in the water and mouse liver was too low to have any direct effect on the toxicity of acephate. Acephate toxicity to aquatic insects would depend on its persistence in water, its uptake by the insects, its conversion to methamidophos, and the combined inhibitory effect of acephate and methamidophos on the cholinesterase enzyme. The toxicity of acephate to mammals would depend on the direct anticholinesterase effect of the chemical and to a small extent on methamidophos.  相似文献   
169.
The aim of this study was to investigate the occurrence of hepatitis E virus (HEV) in sewage samples in Shen Zhen, China. Sewage samples were collected from 152 sewage plants including livestock sewage, domestic sewage and treated sewage from May to July of 2015. Two of 152 samples were HEV positive (1.32%) from the livestock sewage plants. Partial ORF2 fragments of HEV were sequenced and a phylogenetic tree was constructed using MEGA5.1. Blast and phylogenetic analyses showed that both of these two sequences belonged to HEV Genotype 4. To the best of our knowledge, this is the first study on the molecular characterization of HEV in wastewater in China and the first time to detect Genotype 4 in the sewage. Results from this study indicate that the possibilities of sporadic infections of HEV should be emphasized because virus still has the possibility to be circulating in the sewage in China.  相似文献   
170.
Pesticides exposure in Pakistan: a review   总被引:2,自引:0,他引:2  
This is the first systematic review of studies done since 1960, and to give an integrated picture of pesticides exposure to humans, animals, plants, waters, soils/sediments, atmosphere etc. in Pakistan. Authors have extracted data from different departments, published literature in research journals and National reports. Although the wide-spread usage of pesticides in Pakistan has controlled the pests, but like other countries, it has started causing environmental problems in the area. In some areas of Punjab and Sindh groundwater has been found contaminated and is constantly being under the process of contamination due to pesticide use. There is considerable evidence that farmers have overused and misused pesticides especially in cotton-growing areas. It is evident from the biological monitoring studies that farmers are at higher risk for acute and chronic health effects associated with pesticides due to occupational exposure. Furthermore, the intensive use of pesticides (higher sprays more than the recommended dose) in cotton areas involves a special risk for the field workers, pickers, and of an unacceptable residue concentration in cottonseed oil and cakes. The authors have also discussed the merits and demerits of different studies. The review will set the future course of action of different studies on pesticide exposure in Pakistan. Data limitations are still the major obstacle towards establishing clear environmental trends in Pakistan. The authors suggest that a reliable monitoring, assessment and reporting procedures shall be implemented in accordance with appropriate environmental policies, laws and regulations in order to minimize the pesticides exposure.  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