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   232篇
  免费   1篇
安全科学   9篇
废物处理   19篇
环保管理   17篇
综合类   27篇
基础理论   38篇
污染及防治   57篇
评价与监测   60篇
社会与环境   4篇
灾害及防治   2篇
  2023年   5篇
  2022年   8篇
  2021年   3篇
  2020年   1篇
  2019年   2篇
  2018年   3篇
  2017年   6篇
  2016年   9篇
  2015年   8篇
  2014年   27篇
  2013年   45篇
  2012年   6篇
  2011年   3篇
  2010年   15篇
  2009年   13篇
  2008年   12篇
  2007年   10篇
  2006年   12篇
  2005年   9篇
  2004年   1篇
  2003年   5篇
  2002年   2篇
  2001年   3篇
  2000年   3篇
  1999年   1篇
  1998年   3篇
  1995年   4篇
  1987年   1篇
  1985年   1篇
  1982年   1篇
  1981年   2篇
  1979年   1篇
  1977年   1篇
  1976年   1篇
  1974年   1篇
  1960年   1篇
  1943年   1篇
  1942年   1篇
  1937年   1篇
  1936年   1篇
排序方式: 共有233条查询结果,搜索用时 15 毫秒
161.
In order to determine the incidence of confined placental mosaicism (CPM) in term placentae and to show the presence of specific sites and the effect on fetal development, 125 placentae from uneventful pregnancies were analysed by cytogenetic methods. The incidence was at least 4.8 per cent and there were no specific sites on the placenta. Although the number of cases is still too small, we found CPM to be associated with intrauterine growth retardation in six cases.  相似文献   
162.
A method has been developed for indirect determination of cyanide in environmental waters based on cloud point extraction (CPE), preconcentration and determination by flame atomic absorption spectrometry (FAAS). The method was based on reduction of Cu(II) to Cu(I) in the presence of cyanide and complexation of the produced Cu(I)(CN)2? with gallocyanin (GC+) as an ion-pairing reagent at pH 4.0, followed by its extraction into polyethyleneglycol mono-p-nonylphenylether (Ponpe 7.5). Selectivity was improved with the use of suitable masking agents. Various factors influencing separation and preconcentration of cyanide have been investigated, and conditions were optimized, allowing determination of cyanide in the range of up to 1.2 mg L?1 with a detection limit of 0.00045 mg L?1. The method has been applied to the determination of cyanide in environmental waters, the results being in agreement with those obtained by a reference method.  相似文献   
163.
Coastal erosion may be caused by natural causes as well as human factors. Karasu town of the city of Sakarya in Turkey which is a touristic region on the Black Sea coast has been experienced a drastic coastal erosion. In recent years, this erosion reached the threatening dimensions for the structures in the settlement. According to the temporal analyses of Landsat satellite images, the maximum erosion on the coastline was detected 100 m between 1987–2013. The results of the study show that the harbour construct on the Karasu coast has the major impact on this event. The secondary factor is that the amount of the sediment carried by the Sakarya River was decreased in time due to different reasons. To prevent the coastal erosion, a series of offshore breakwaters were planned after the failed application of groins on the coastline. In this study, temporal changes of the coastline are investigated by the Landsat satellite data and land surveys, possible reasons of the erosion are discussed and the solutions are proposed regarding the coastal structures.  相似文献   
164.
The aim of this study was to investigate the relationship between organizational climate and driver behaviours of professional drivers. The sample consisted of 230 male professional drivers. The participants completed a questionnaire including the Driver Behaviour Questionnaire (DBQ), Hofstede’s Organizational Culture Scale, and a background information form. Results of the factor analysis of Hofstede’s Organizational Culture Scale yielded two dimensions, which were named as “work orientation” and “employee consideration”. Analyses of Covariance (ANCOVA) revealed significant main and interaction effects of organizational climate on errors, and violations after controlling for the statistical effects of age, annual mileage and the organization types. Drivers with low scores of work orientation reported significantly higher frequencies of errors and violations than drivers with high scores of work orientation. It was also found that drivers with low scores of employee consideration reported higher frequencies of errors and violations than drivers with high scores of employee consideration. The effect of interaction between work orientation and employee consideration dimensions was only found on the frequencies of violations.  相似文献   
165.
Journal of Material Cycles and Waste Management - Nowadays, textile waste arising from increasing clothing production, consumption, and disposal activities has led to environmental, social, and...  相似文献   
166.
Volatile organic compounds (VOCs) such as benzene, toluene, ethylbenzene, and xylene (BTEX) along with inorganic gases such as sulfur dioxide (SO2), nitrogen dioxide (NO2), and ozone (O3) levels were found in the atmosphere of the Kemerburgaz region where environmental issues became a major concern due to nearby incineration plant and waste disposal facility in Istanbul. Ten sampling locations were selected considering possible sources in the study area. The sampling areas were classified as suburban, industrial, rural, and background regions. Sampling campaigns were carried out for four-week periods from March 2011 to August 2012 in all locations. Elevated concentrations of BTEX around roads and the industrial locations indicated that vehicle exhaust and industrial activities were the main sources of these pollutants in the region. Concentrations of NO2 were also high around roads. A much more uniform distribution was observed for SO2 during sampling periods. However higher levels were observed at suburban locations due to the use of coal for local heating especially during winter. Ozone concentrations were low at the industrial locations and roadsides, but high in suburban and rural locations downwind from the sources. The results of these organic and inorganic gases meet the national limit values. Furthermore, a lifetime risk assessment methodology was used to evaluate the potential adverse health effects of BTEX. The mean cancer risk level for benzene was estimated to be 7.71E-07 that is lower than assigned acceptable risk level of 1.0E-04. Toluene, ethylbenzene, and xylenes were lower than the specified level of 1.0 with respect to mean non-carcinogenic risks. The findings reveal that determined BTEX emissions do not pose a health threat to residents in the studied region.  相似文献   
167.
Abstract

Particle emissions of modern diesel engines are of a particular interest because of their negative health effects. The special interest is in nanosized solid particles. The effect of an open channel filter on particle emissions of a modern heavy-duty diesel engine (MAN D2066 LF31, model year 2006) was studied. Here, the authors show that the open channel filter made from metal screen efficiently reduced the number of the smallest particles and, notably, the number and mass concentration of soot particles. The filter used in this study reached 78% particle mass reduction over the European Steady Cycle. Considering the size-segregated number concentration reduction, the collection efficiency was over 95% for particles smaller than 10 nm. The diffusion is the dominant collection mechanism in small particle sizes, thus the collection efficiency decreased as particle size increased, attaining 50% at 100 nm. The overall particle number reduction was 66–99%, and for accumulation-mode particles the number concentration reduction was 62–69%, both depending on the engine load.  相似文献   
168.
169.
Abstract

The removal of 2, 4‐D (2, 4‐ dichlorophenoxyacetic acid) from aqueous solutions by activated spent bleaching earths (SBE) was studied at 20 °C. Experiments were performed as a function of time, initial concentration, dose and particle size of the adsorbent. The Langmuir and Freundlich adsorption equations were fitted by the adsorption data obtained. The values of Langmuir and Freundlich constants were determined. The adsorption kinetic was found to follow Lagergren equation. Both the boundary layer and intraparticle diffusion played important roles in the adsorption rate of 2, 4‐D. As the size of the adsorbent increased, the time to reach equilibrium increased but adsorption capacity decreased.  相似文献   
170.
In this study, prediction capacities of multi-linear regression (MLR) and artificial neural networks (ANN) onto coarse particulate matter (PM10) concentrations were investigated. Different meteorological factors on particulate pollution were chosen for operating variables in the model analyses. Two different regions (urban and industrial) were identified in the region of Kocaeli, Turkey. All data sets were obtained from air quality monitoring network of the Ministry of Environment and Urban Planning, and 120 data sets were used in the MLR and ANN models. Regression equations explained the effects of the meteorological factors in MLR analyses. In the ANN model, backpropagation network with two hidden layers has achieved the best prediction efficiency. Determination coefficients and error values were examined for each model. ANN models displayed more accurate results compared to MLR.  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