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   152篇
  免费   1篇
  国内免费   9篇
安全科学   3篇
废物处理   24篇
环保管理   9篇
综合类   35篇
基础理论   27篇
环境理论   2篇
污染及防治   45篇
评价与监测   4篇
社会与环境   8篇
灾害及防治   5篇
  2023年   2篇
  2022年   2篇
  2021年   1篇
  2020年   2篇
  2018年   1篇
  2017年   3篇
  2016年   5篇
  2015年   4篇
  2014年   7篇
  2013年   16篇
  2012年   11篇
  2011年   7篇
  2010年   11篇
  2009年   9篇
  2008年   9篇
  2007年   17篇
  2006年   6篇
  2005年   9篇
  2004年   10篇
  2003年   4篇
  2002年   5篇
  2000年   1篇
  1996年   1篇
  1994年   3篇
  1992年   2篇
  1990年   1篇
  1989年   2篇
  1988年   1篇
  1984年   1篇
  1982年   1篇
  1981年   1篇
  1979年   2篇
  1977年   1篇
  1975年   1篇
  1967年   1篇
  1964年   1篇
  1959年   1篇
排序方式: 共有162条查询结果,搜索用时 31 毫秒
91.
The simple ATDL urban dispersion model Is based on the formula Xo(g/m3) = CO(g/m2s)/U(m/s). The diurnal variation of the stability factor C, which can be thought of as the width of the urban area divided by the vertical dispersion of the pollution cloud, has not before been satisfactorily estimated. Using observed diurnal variations of CO concentrations and traffic frequencies reported by DeMarrais of the EPA for many stations in the states of Maryland, New Jersey, and Colorado, and using wind data from these states, hourly values of C - XoU/Q were calculated. The ratio of C to the daily average C is found to equal about 2.5 at 4 a.m., drops to about 0.5 by 8 a.m., and remains at 0.5 until about 6 p.m.., when it starts to climb slowly again. Application of this new stability factor to independent CO data from Los Angeles yields correlations between measured and predicted concentrations of about 0.7.  相似文献   
92.
93.
基于营养系统的灾害避难所规划的概念模型   总被引:2,自引:0,他引:2  
通过对比中、日、美3国的灾害避难所及其规划设计指导手册,总结了灾害避难所的基本类型和避难所规划的空间尺度(范围).从营养系统的角度给出了避难所规划的3个大类及8个实施标准,并以此为基础,提出了灾害避难所规划或评价的3个基本模式.  相似文献   
94.
The goal of integrated disaster risk management is to promote an overall improvement in the quality of safety and security in a region, city or community at disaster risk. This paper presents the case for a thorough overhaul of the institutional component of integrated disaster risk management. A review of disaster management institutions in the United States indicates significant weaknesses in their ability to contribute effectively to the implementation of integrated disaster risk management. Our analysis and findings identify eight key elements for the design of dynamic new disaster management institutions. Six specific approaches are suggested for incorporating the identified key elements in building new institutions that would have significant potential for enhancing the effective implementation of integrated disaster risk management. We have developed a possible blueprint for effective design and construction of efficient, sustainable and functional disaster management institutions.  相似文献   
95.
The gene expression of environmental organisms is useful as a biomarker of environmental pollution. One of its advantages is high sensitivity. We identified the cDNA of a novel cadmium-responsive gene in the soil collembolan Folsomia candida. The deduced protein, designated “metallothionein-like motif containing protein” (MTC), was cysteine-rich and contained a metallothionein-like motif with similarity to metallothionein, but had a much longer sequence than metallothionein and contained repeated sequences of amino acids. Expression of MTC mRNA was sensitively induced by cadmium exposure at 0.3 mg/kg of dry food, a concentration at which toxic effects are not observed, but expression was not affected by γ-ray exposure (an inducer of oxidative stress). These findings suggest that MTC is involved in cadmium-binding processes rather than in oxidative-stress responses. In conclusion, we suggest that gene expression of MTC may be a candidate biomarker for detecting low levels of cadmium contamination in soil.  相似文献   
96.
Rice (Oryza sativa L.) plants were cultivated in an experimental field and separated at harvest into different components, including polished rice, rice bran, hull, straw, and root. The contents of iodine in these components and the soil were determined by inductively coupled plasma-mass spectrometry and radiochemical neutron activation analysis, respectively. Iodine content varied by more than three orders of magnitude among the plant components. Mean concentration of iodine in the entire plants was 20 mg kg(-1) dry weight, and the concentration of iodine in the surface soil (0-20 cm depth) was 48 mg kg(-1). The highest concentration of iodine (53 mg kg(-1) dry weight) was measured in root and the lowest concentration (0.034 mg kg(-1) dry weight) in polished rice. While the edible component (polished rice) accounted for 32% of the total dry weight, it contained only 0.055% of iodine found in the entire rice plants. Atmospheric gaseous iodine (5.9 ng m(-3)) was estimated to contribute <0.2% of the total iodine content in the biomass of rice plants; therefore nearly all of the iodine in the rice plants was a result of the uptake of iodine from the soil. The content of iodine in the aboveground part of rice plants was 16 mg kg(-1) dry weight and the percentage of iodine transferred per cropping from the soil into the aboveground biomass corresponded to 0.27% (20 mg m(-2)) of the upper soil layer content.  相似文献   
97.
Detecting dispersal pathways is important both for understanding species range expansion and for managing nuisance species. However, direct detection is difficult. Here, we propose detecting these crucial pathways using a virtual ecology approach, simulating species dynamics using models, and virtual observations. As a case study, we developed a dispersal model based on cellular automata for the pest insect Stenotus rubrovittatus and simulated its expansion. We tested models for species expansion based on four landscape parameters as candidate pathways; these are river density, road density, area of paddy fields, and area of abandoned farmland, and validated their accuracy. We found that both road density and abandoned area models had prediction accuracy. The simulation requires simple data only to have predictive power, allowing for fast modeling and swift establishment of management plans.  相似文献   
98.
The policy instruments that provide information on a firm’s or facility’s environmental performance, such as the U.S. Toxic Release Inventory (TRI) and the Pollutant Release and Transfer Register system (PRTRs) used in some European countries and Japan, play an important role in encouraging firms or facilities to improve their environmental performance, if investors, consumers and residents recognize their environmental performance. This study uses a hedonic approach to explore how the Japanese rental housing market responds to carcinogenic risk arising from releases and transfers of chemical substances produced and used at close facilities. We found that residents do not perceive carcinogenic risk generated more than 1.0 km away from their residence and that they seem to recognize the increased carcinogenic risk at distances from 0.5 km to 1.0 km away; a 1% increase in carcinogenic risk reduces the average rent by 0.0007%. The distance at which residents perceive the risk arising from such facilities is less than in previous studies. This suggests that the risk perception recognized in previous studies may capture the other externalities in addition to the chemical risk because the risk is measured by the distance.  相似文献   
99.
Experience-dependent tactics of males trying to gain access to females were examined in the beetle Gnatocerus cornutus, which engages in male–male fighting for mates. In male fights, subsequent behavior is modified by winning and losing experiences. Males, therefore, may choose between several behavioral tactics to obtain a mate, based on his previous fighting experience. In G. cornutus, we examined for how long aggressive behaviors were modified by experiences of winning or losing, i.e., the duration of the prior experience effect. Losing decreased a male's frequency of fighting for 4 days, and few defeated males fought any male regardless of the opponent's size. By the fifth day, this effect disappeared. No modulation of male behavior due to winning was observed. Furthermore, the experience of losing not only decreased a male's aggressiveness but also switched the male behavior from fighting to dispersal from the fight site to another site. In future, it is necessary to clarify why the optimal term of the losing experience is 4 days in this beetle.  相似文献   
100.
The chemistry and flow of water in the abandoned Tomitaka mine of Miyazaki, western Japan were investigated. This mine is located in a non-ferrous metal deposit and acid mine drainage issues from it. The study was undertaken to estimate the quantities of mine drainage that needs to be treated in order to avoid acidification of local rivers, taking into account seasonal variations in rainfall. Numerical models aimed to reproduce observed water levels and fluxes and chemical variations of groundwater and mine drainage. Rock–water interactions that may explain the observed variations in water chemistry are proposed. The results show that: (1) rain water infiltrates into the deeper bedrock through a highly permeable zone formed largely by stopes that are partially filled with spoil from excavations (ore minerals and host rocks); (2) the water becomes acidic (pH from 3 to 4) as dissolved oxygen oxidizes pyrite; (3) along the flow path through the rocks, the redox potential of the water becomes reducing, such that pyrite becomes stable and pH of the mine drainage becomes neutral; and (4) upon leaving the mine, the drainage becomes acidic again due to oxidation of pyrite in the rocks. The present numerical model with considering of the geochemical characteristics can simulate the main variations in groundwater flow and water levels in and around the Tomitaka mine, and apply to the future treatment of the mine drainage.  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