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   1421篇
  免费   34篇
  国内免费   20篇
安全科学   59篇
废物处理   76篇
环保管理   144篇
综合类   289篇
基础理论   256篇
环境理论   2篇
污染及防治   394篇
评价与监测   147篇
社会与环境   88篇
灾害及防治   20篇
  2023年   10篇
  2022年   18篇
  2021年   31篇
  2020年   18篇
  2019年   19篇
  2018年   42篇
  2017年   51篇
  2016年   52篇
  2015年   35篇
  2014年   62篇
  2013年   105篇
  2012年   50篇
  2011年   83篇
  2010年   64篇
  2009年   72篇
  2008年   77篇
  2007年   79篇
  2006年   53篇
  2005年   59篇
  2004年   63篇
  2003年   78篇
  2002年   53篇
  2001年   54篇
  2000年   33篇
  1999年   28篇
  1998年   18篇
  1997年   13篇
  1996年   7篇
  1995年   16篇
  1994年   10篇
  1993年   14篇
  1992年   16篇
  1991年   3篇
  1990年   6篇
  1989年   7篇
  1988年   6篇
  1987年   2篇
  1986年   5篇
  1985年   8篇
  1984年   4篇
  1983年   9篇
  1982年   8篇
  1981年   5篇
  1980年   3篇
  1979年   2篇
  1976年   2篇
  1970年   2篇
  1962年   5篇
  1961年   2篇
  1938年   1篇
排序方式: 共有1475条查询结果,搜索用时 15 毫秒
1.
公路设计中的环境保护工作   总被引:1,自引:0,他引:1  
阐述了公路建设中环境保护工作的意义,提出在公路工程勘察设计工作中对环境保护的典型作法和取得的效果。  相似文献   
2.
3.
海河下游水体中DO与NH_3-N、COD_(Mn)相关关系探讨   总被引:2,自引:0,他引:2  
本文应用近年来海河下游监测数据对DO与NH3N和CODMn进行一元线性回归,得到两回归方程:NH3N=-128DO+1054;CODMn=-113DO+1692。并经相关系数和回归系数显著性检验,表明在999%的置信水平下DO与NH3N和CODMn线性相关均极其显著  相似文献   
4.
Exposure to lead (Pb) may affect adversely human health. Mapping soil Pb contents is essential to obtain a quantitative estimate of potential risk of Pb contamination. The main aim of this paper was to determine the soil Pb concentrations in the urban and peri-urban area of Cosenza–Rende to map their spatial distribution and assess the probability that soil Pb concentration exceeds a critical threshold that might cause concern for human health. Samples were collected at 149 locations from residual and non-residual topsoil in gardens, parks, flower-beds, and agricultural fields. Fine earth fraction of soil samples was analyzed by X-ray Fluorescence spectrometry. Stochastic images generated by the sequential Gaussian simulation were jointly combined to calculate the probability of exceeding the critical threshold that could be used to delineate the potentially risky areas. Results showed areas in which Pb concentration values were higher to the Italian regulatory values. These polluted areas were quite large and likely, they could create a significant health risk for human beings and vegetation in the near future. The results demonstrated that the proposed approach can be used to study soil contamination to produce geochemical maps, and identify hot-spot areas for soil Pb concentration.  相似文献   
5.
The principal aim of this study was to define and apply a procedure based on a structured questionnaire survey useful to analyze the people’s environmental knowledge in order to select the areas and age groups with a low level of knowledge in a municipality (in Southern Italy) and, therefore, suggest a specific educational campaign for each. The detailed sampling procedure made it possible to carry out a meticulous statistical analysis of the results. The youngest and oldest people showed the lowest level of awareness for each district. A high level of education did not necessarily imply a high level of environmental awareness as well as a greater acceptance of MSW facilities. The satisfaction level of the recycling program was higher amongst the oldest age group. All the citizens in the several areas were unanimous in pointing out the presence of dirt in the street as the main shortcoming of the bring separate collection program. Only the youngest age group self-criticised, considering that they revealed a low level of participation to the separate collection program. While, the oldest people retaining them less influential, claimed that the citizens were not responsible for the failure of the separate collection program. The prevailing opinion of the sample was that people protested against the construction of waste facilities because they were not well-informed, with the most significant opinion of all the age subdivisions being that incineration is a hazardous treatment. The presence of criminal organizations was indicated as the main reason why the Campania Region suffers a serious solid waste emergency. While, the percentage of people pointing their finger at politicians increases with the average age of the respondents with there being a very strong correlation (r2 = 0.9903).  相似文献   
6.
Large-scale studies are essential to assess the emission patterns and spatial distribution of organohalogenated pollutants (OHPs) in the environment. Bird eggs have several advantages compared to other environmental media which have previously been used to map the distribution of OHPs. In this study, large-scale geographical variation in the occurrence of OHPs, such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and organochlorine pesticides (OCPs), was investigated throughout Europe using eggs of a terrestrial residential passerine species, the great tit (Parus major). Great tit eggs from 22 sampling sites, involving urban, rural and remote areas, in 14 European countries were collected and analysed (5-8 eggs per sampling site). The environmentally most important congeners/compounds of the analysed pollutants were detectable in all sampling locations. For PCBs, PBDEs and OCPs, no clear geographical contamination pattern was found. Sum PCB levels ranged from 143 ng/g lipid weight (lw) to 3660 ng/g lw. As expected, PCB concentrations were significantly higher in the sampled urban compared to the remote locations. However, the urban locations did not show significantly higher concentrations compared to the rural locations. Sum PBDEs ranged from 4.0 ng/g lw to 136 ng/g lw. PBDEs were significantly higher in the urbanized sampling locations compared to the other locations. The significant, positive correlation between PCB and PBDE concentrations suggests similar spatial exposure and/or mechanisms of accumulation. Significantly higher levels of OCPs (sum OCPs ranging from 191 ng/g lw to 7830 ng/g lw) were detected in rural sampling locations. Contamination profiles of PCBs, PBDEs and OCPs differed also among the sampling locations, which may be due to local usage and contamination sources. The higher variance among sampling locations for the PCBs and OCPs, suggests that local contamination sources are more important for the PCBs and OCPs compared to the PBDEs. To our knowledge, this is the first study in which bird eggs were used as a monitoring tool for OHPs on such a large geographical scale.  相似文献   
7.
Gamma-ray spectra from more than 50 samples of food products available in stores of Buenos Aires city were measured using a germanium detector. Activity concentrations of 137Cs up to 10 Bq/kg were found in tea and yerba mate manufactured in Apóstoles, Argentina. Further measurements of tea leaves, yerba mate leaves and soils, all coming from a cultivated area in that region, also show the presence of 137Cs contamination. The results suggest that the area was fertilized with a product that originated in a region affected by the fallout from the Chernobyl nuclear plant accident.  相似文献   
8.
To collect regional information on internal levels of pollutants in humans in Flanders, 1196 mother–child pairs were systematically recruited in 2002–2003 via 25 maternities across Flanders. Cd, Pb, PCB congeners 118, 170, 138, 153 and 180, p,p′-DDE — a key metabolite of DDT- and hexachlorobenzene (HCB) were measured in cord blood or plasma. Cd was detected in 64% of the samples (geometric mean 0.21 µg/L cord blood). p,p′-DDE (110 ng/g plasma lipids) and Pb (14.7 µg/L blood), were measurable in nearly all samples. The individual PCB congeners could be detected in 40 to 81% of the newborns (138 + 153 + 180 = 64.4 ng/g plasma lipids). HCB (18.9 ng/g plasma lipids) and dioxin-like compounds measured by DR-CALUX® (23 pg CALUX-TEQ/g lipids) were above detection limit in more than 75% of the samples. Age and smoking habits of the mothers, did not influence the cord blood Pb and Cd levels. The organochlorines increased 4 to 9% per year of the mother's age (partial R= 0.05 to 0.22). Mothers had 2.6% less PCBs in cord blood (partial R= 0.02) for each unit increase in pre-pregnancy BMI. Season of delivery, breastfeeding previous children or consumption of local dairy products, were minor determinants. Up to 20% of the variability in organochlorine concentrations was explained by residence area. It was concluded that the place of birth in Flanders is an important determinant of the load of pollutants measured at the start of life. This underlines the validity of human biomonitoring on (relatively) small geographical scale.  相似文献   
9.
First available data on atmospheric fall-out were provided by sampling monthly bulk depositions in four sites inside the Lagoon of Venice (550 km2). Sampling was carried out monthly during the period July 1998-July 1999, in one site near an industrial area (Porto Marghera; site D), another site in the city of Venice (site A), and the remaining two in the southern- and northernmost ends of the Lagoon (Valle Figheri, site C; Valle Dogà site B). The following determinations were carried out for each samples: pH, conductivity, grain-size, particulate load, and dissolved nutrients (N, P). Samples were then subdivided into soluble and insoluble fractions, and Al, Ca, Na, K, Mg, Si, Mn, Fe, Zn, Ni, Cr, Cu, Pb, Cd, As, Hg, Ti, V, S, P, Se and Sb were analysed on both fractions. Total organic micropollutants (PAH, PCB, HCB, DDT, PCDD/F) were measured. As regards particle size distribution, there was great variability among sampling sites. The percentage of the < or =2 microm grain-size fraction was higher in the southern and northern ends of the Lagoon. Small differences were found among sites for major elements, whereas higher variability was observed for inorganic and organic micropollutants, with standard deviations between 20% and 60% of the fluxes measured. Major differences in annual fluxes between the most polluted sites (mostly D and A) and background (site B) were seen for Cd (0.26 vs. 0.06 mg m(-2) year(-1)), Hg (41 vs. 15 microg m(-2) year(-1)), PCB ( approximately 2500 vs. approximately 500 ng m(-2) year(-1)) and HCB ( approximately 8000 vs. approximately 1000 ng m(-2) year(-1)). Comparisons with previous data, collected in the periods 1993-1994 and 1995-1997, were only available for a few trace metals. A definite decline in the annual Pb flux in the city of Venice was detected, from 18 to 13 mg m(-2) in 1996/1997 and 1995/1996 respectively, to approximately 5 mg m(-2) in the present study. Total annual deposition was calculated by means of two different methods, which gave very similar results: (i) the mean value of deposition in the four sites was multiplied by lagoon area (550 km2); (ii) the monthly rain isopleths were combined to normalize deposition values. The figures are: 15-34 kg of Hg and Sb, approximately 200 kg of As, approximately 100 kg of Cd and PAH, 0.7-1.3 tons of Cr, Ni and V, more than 2 tons of Cu and Pb, 17 of Zn, 55 of total P, approximately 200 of Al, and 3900 of DIN. Total fluxes of organics inside the lagoon were: PAH approximately 100 kg; HCB approximately 1 kg; DDT approximately 0.4 kg. PCB and PCDD/F fluxes were approximately 500 g and approximately 10 g, corresponding respectively to 0.1 and 0.4 g I-TE. The correlations between fluxes of inorganic micropollutants and grain-size were significant. Multivariate statistical analysis was applied to investigate more accurately relationships between the insoluble and dissolved fractions of inorganic micropollutants and grain-size fractions. In particular, significant correlations were highlighted between the dissolved fraction of As and the < or =1 mum particle size fraction. Relations between levels of SigmaPCDDF, SigmaPCDD, PCB and PAH congeners and grain-size revealed significant correlation coefficients for the remote sites (B, C), and none in the urban and industrial sites (A, D). In particular, significant correlations were highlighted between SigmaPCDDF, SigmaPCDD and particle size fraction < or =2 mum, and between benzo(a)pyrene and PCB 167 and particle size fraction 4-8 mum.  相似文献   
10.
基于1995~2010武汉城市圈城乡路网空间数据,综合运用复杂网络理论、动力系统理论及现代控制理论等多学科的方法和理论,采取随机故障和蓄意侵略两种攻击策略及多种评价指标,通过建立动力学演化模型并进行模拟仿真,揭示武汉城市圈城乡道路网的空间稳定性:(1)因分布相对均匀,节点连接随机多样,在面临随机攻击时,武汉城市圈城乡路网体现出“类随机性”,抗攻击能力强;(2)高度节点、高介数节点失效时,引致的城乡路网效率和结构变化程度不一,高介数节点失效往往更容易导致路网破碎和效率降低(形成众多子图);(3)桥梁和高速成为整个圈域城乡路网的关键边,不同桥梁或高速路段相对网络稳定性的重要程度不一样:圈域中心城区的大桥和二桥、南北向的京港澳、大广高速成为整个城乡路网的关键路径  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