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   1015篇
  免费   11篇
  国内免费   15篇
安全科学   43篇
废物处理   38篇
环保管理   122篇
综合类   190篇
基础理论   170篇
环境理论   1篇
污染及防治   345篇
评价与监测   70篇
社会与环境   47篇
灾害及防治   15篇
  2023年   17篇
  2022年   22篇
  2021年   34篇
  2020年   27篇
  2019年   23篇
  2018年   48篇
  2017年   48篇
  2016年   57篇
  2015年   37篇
  2014年   60篇
  2013年   72篇
  2012年   61篇
  2011年   81篇
  2010年   52篇
  2009年   42篇
  2008年   63篇
  2007年   58篇
  2006年   63篇
  2005年   44篇
  2004年   34篇
  2003年   18篇
  2002年   18篇
  2001年   9篇
  2000年   8篇
  1999年   2篇
  1998年   3篇
  1997年   7篇
  1996年   2篇
  1995年   5篇
  1994年   2篇
  1993年   3篇
  1992年   1篇
  1991年   2篇
  1990年   1篇
  1989年   2篇
  1988年   1篇
  1986年   2篇
  1984年   1篇
  1966年   1篇
  1961年   1篇
  1960年   1篇
  1959年   1篇
  1958年   1篇
  1957年   1篇
  1954年   3篇
  1951年   1篇
  1936年   1篇
排序方式: 共有1041条查询结果,搜索用时 421 毫秒
301.
The present study deals with the application of the self-organizing map (SOM) technique in the exploration of spatiotemporal dynamics of spring and stream water samples collected in the Chocho?owski Stream Basin located in the Tatra Mountains (Poland). The SOM-based classification helped to uncover relationships between physical and chemical parameters of water samples and factors determining the quality of water in the studied high-mountain area. In the upper part of the Chocho?owski Stream Basin, located on the top of the crystalline core of the Tatras, concentrations of the majority of ionic substances were the lowest due to limited leaching. Significantly higher concentration of ionic substances was detected in spring and stream samples draining sedimentary rocks. The influence of karst-type springs on the quality of stream water was also demonstrated.  相似文献   
302.
The aim of this study was to determine 19 elements contents and bioconcentration potential in fruiting bodies of Parasol Mushroom (Macrolepiota procera) collected from the Tucholskie Forest complex in Poland. Also discussed were Cd, Pb and Hg contents of edible caps in relation to the current regulatory standards. K, P and Mg were particularly abundant in caps and stipes, median values were 38-49, 13, and 1.6-1.6 mg/g dry weight, and followed by Ca, Na and Rb at 110-540, 44-240 and 20-50 μg/g dw, respectively. Concentrations of Al, Fe, Zn, Cu and Mn were from less than 50 to 180 μg/g dw, while concentrations of other elements were ~l.0?μg/g dw or less. Cu, K, Ag, Cd, Na, Rb, Zn and Hg were bioconcentrated (BCF >1), while Al, Ba, Fe, Mn, Co, Sr, Pb and Cr were not bioaccumulated (BCF <1). Cd and Pb content of Parasol Mushroom's edible caps collected from some sites in the Tucholskie Forest exceed the maximum levels set in the EU for cultivated mushrooms.  相似文献   
303.

Background

Continuous monitoring of air quality is implemented by government institutions at fixed ambient sites. However, the correlation between fixed site measurements and exposure of individual persons to air contaminants is likely to be weak.

Materials and methods

We measured particulate matter both outdoors and indoors by following the spatial movement of individuals. Sixteen test persons took part and carried a measurement backpack for a 24-h period. The backpack was comprised of a Grimm Aerosol Spectrometer model 1.109, a GPS device, and a video camera for tracking of human behavior. The spectrometer provided information about particle numbers and mass in 32-size classes with a high temporal resolution of 6 s.

Results

The personal exposure of individuals during 24 h could significantly exceed the outdoor particulate matter (PM)10 concentrations measured at the fixed sites. The average 24-h exposure of all test persons for PM10 varied from 27 to 322 ??g m?3. Environmental tobacco smoke and cooking emissions were among the main indoor sources for PM. The amount of particulate matter a test person was exposed to was highly dependent on the spatial behavior and the surrounding microenvironment conditions.

Discussion

Large-scale experiments including personal measurements might help to improve modeling approaches to approximate the actual exposure on a statistically sound basis.  相似文献   
304.
CO2-loads from combustible waste are important inputs for national CO2 inventories and life-cycle assessments (LCA). CO2 emissions from waste incinerators are often expressed by emission factors in kg fossil CO2 emitted per GJ energy content of the waste. Various studies have shown considerable variations between emission factors for different incinerators, but the background for these variations has not been thoroughly examined. One important reason may be variations in collection of recyclable materials as source separation alters the composition of the residual waste incinerated. The objective of this study was to quantify the importance of source separation for determination of emission factors for incineration of residual household waste. This was done by mimicking various source separation scenarios and based on waste composition data calculating resulting emission factors for residual waste routed to incineration. Emission factors ranged from 27 to 40 kg CO2/GJ. The results appeared most sensitive towards variations in waste composition and water content. Recycling rates and lower heating values could not be used as simple indicators of the resulting emission factors for residual household waste; however the fossil carbon ratio of the waste after source separation was found to be appropriately correlated with the emission factor. Based on the results, it is recommended to carefully evaluate the source separation and collection systems behind reported literature values when comparing different studies and when using the values for environmental assessment purposes.  相似文献   
305.
Qin YY  Leung CK  Leung AO  Zheng JS  Wong MH 《Chemosphere》2011,82(9):1329-1336
This study aims to investigate levels of POPs in meat, edible oils, nuts, milk and wine collected from Hong Kong. Naphthalene, pp-DDE, beta-, gamma-HCH and PBDE 47 were detected in most of the food items. Goose liver accumulated the highest PAHs (47.9 ng g−1 wet wt), DDTs (25.6), HCHs (13.0), PCBs (4.17), PBDEs (468 pg g−1 wet wt) among all the selected food. Meat and nut groups had significant (p < 0.01 or 0.05) correlations between lipid contents and concentrations of PAHs (meat: r = 0.878), HCHs (meat: r = 0.753), DDTs (meat: r = 0.937; nuts: r = 0.968) and PCBs (meat: r = 0.832; nut: r = 0.946). The concentrations of DDTs, HCHs and PCBs in vegetable oil were lower, but HCHs in fish oil were higher, when compared with other countries. The concentrations of PAHs, DDTs, PCBs and PBDEs in food tested in the present study were all below various safety guidelines.  相似文献   
306.
Are economic incentives and regulatory relief useful tools for encouraging reuse of abandoned or under-utilised urban sites with historic buildings? Answering this question is of key importance for many European cities and for older US cities, and has important implications in terms of urban sustainability and “smart growth” initiatives. This study uses conjoint choice experiments to explore the relative importance of economic incentives, regulatory relief, land use and property regime offerings at under-utilised historic sites in Venice, Italy. Real estate developers and investors were surveyed, and asked to choose between pairs of hypothetical projects in three Venice locations, as well as between one of these projects and the alternative to do a development project elsewhere. Statistical models of the responses to these choice questions indicate that respondents were sensitive to the price of acquiring the land (and hence to any policies that influence prices), and particularly sensitive to the property regime that would be granted to developers and investors and to the allowable land use. It is concluded that the city should focus on offering land uses and property regimes that are more in tune with developer demand.  相似文献   
307.
This article investigates attitudes towards co-management of protected areas in Sweden, at the national, county and local level. In Sweden, protected areas are still primarily designated and managed hierarchically-a practice increasingly contested by people living close to them, including indigenous Sámi reindeer herders whose economic activities are located within protected areas. The general view could, on the contrary, be anticipated to be pro-state since protected areas are considered to be of national interest. For democratic reasons, however, the opinions of the whole population should be considered. In order to measure both local and general views, this study is based on a two-sample survey of 8868 respondents. The objectives are to map and explain attitudes regarding who should manage protected areas in Sweden, and to test the usefulness of a multi-level quantitative method. Such an approach is unusual in co-management literature that is empirically mainly based on local case studies. The explanatory ambition sets out to test three hypotheses drawn from common-pool resource theory; resource dependency, common understanding, and trust. Perhaps surprisingly, the results show that a considerable majority of the respondents (at all levels) wish to see self- or co-management. All three hypotheses are important to understand attitudes toward the management of protected areas, but not always in the way that the theory anticipates.  相似文献   
308.
Spatio-temporal variations of biochemical oxygen demand (BOD) and total coliform (TC) in the Han River, Korea, were investigated in terms of concentration-based and mass loading-based approaches. Considering the river water quality criteria regulated by the Ministry of Environment in Korea, the tributaries linked to the mainstream of the Han River were found to be highly contaminated with respect to both BOD and TC and, in fact, most of the tributaries exceeded the maximum water quality criteria. To evaluate the pollution impact of tributaries on the mainstream, the monthly water quality monitoring data for six years (from 1995 to 2000) were collected from the Han River basin, and statistically analyzed using Pearson’s correlation coefficient. The results revealed that mass loading-based approach was superior to the concentration-based approach for effective Han River watershed management. Overall results supported that the mass loading-based approach associated with total maximum daily loads (TMDL) management would be a useful and suitable protocol in watershed management for improving the water quality of the Han River and protecting public health. Therefore, this study supporting TMDL management can be applicable to a wide array of contaminants and watershed settings in Korea.  相似文献   
309.
Three wastewater samples from a pharmaceutical plant formulating medical ointments were subjected to lab-scale treatment by a Fenton-like system in combination with lime coagulation. All samples were plant pre-treated by adsorption/flocculation/filtration processes with utilization of bentonite, but the quality of effluents did not comply with the regulations for wastewater discharged to local sewerage. The optimization of Fenton-like oxidation demonstrated the highest process efficacy at H(2)O(2)/COD weight ratio of 2:1, H(2)O(2)/Fe(2+) molar ratio of 10:1 and 2h of treatment time. The fast pH decrease to acidic values approximately 3 during first min of oxidation for all effluents suggested that pH adjustment was unnecessary. Combination of Fe(III) precipitation and lime coagulation proved feasible to improve considerably COD and residual iron concentration reduction in pharmaceutical effluents. Additionally, considerable BOD(7) reduction and BOD(7)/COD ratio improvement of pharmaceutical wastewater samples was achieved by combined treatment. The application of Fenton-like oxidation with subsequent iron (III)/lime coagulation did not only enhance the quality of pharmaceutical effluents with different chemical characteristics and help to meet the requirements for wastewater discharged to sewage, but also improve the biodegradability of pharmaceutical effluents.  相似文献   
310.
Axmon A  Hagmar L  Jönsson BA 《Chemosphere》2008,70(9):1620-1628
To investigate a possible time trend in serum concentrations of persistent organochlorine pollutants (POPs), representative samples of the young (median age 18 years) Swedish male population were investigated in the years 2000 and 2004. Due to their low age, these men were assumed not to have reached steady state of body burdens of POPs, why their serum concentrations were considered to represent ongoing dietary exposure. Serum concentrations of 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) and 1,1-dichloro-2,2-bis(4-chlorophenyl)-ethylene (p,p'-DDE), two biomarkers of exposure to POPs, were available for 274 and 223 men, respectively, in 2000 and for 200 men in 2004. The percentage of men with CB-153 or p,p'-DDE below the limit of detection (LOD) was significantly higher in 2004 than in 2000 (30% vs. none, p < 0.001 for CB-153 and 65% vs. 6%, p < 0.001 for p,p'-DDE). Moreover, the median serum concentration of CB-153 decreased from 66 ng g(-1) lipid to 19 ng g(-1), corresponding to a yearly decrease of about 26%. The analogous analysis was not done for p,p'-DDE since the median serum concentration in 2004 was below the LOD.  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