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   200篇
  免费   2篇
  国内免费   1篇
安全科学   3篇
废物处理   15篇
环保管理   16篇
综合类   24篇
基础理论   51篇
污染及防治   64篇
评价与监测   15篇
社会与环境   14篇
灾害及防治   1篇
  2023年   2篇
  2022年   5篇
  2021年   9篇
  2020年   6篇
  2019年   4篇
  2018年   5篇
  2017年   6篇
  2016年   6篇
  2015年   4篇
  2014年   11篇
  2013年   20篇
  2012年   14篇
  2011年   16篇
  2010年   9篇
  2009年   4篇
  2008年   11篇
  2007年   14篇
  2006年   8篇
  2005年   5篇
  2004年   6篇
  2003年   3篇
  2002年   7篇
  2001年   2篇
  2000年   4篇
  1999年   3篇
  1998年   1篇
  1997年   1篇
  1996年   1篇
  1995年   2篇
  1994年   1篇
  1993年   1篇
  1990年   3篇
  1989年   2篇
  1988年   2篇
  1985年   2篇
  1984年   2篇
  1983年   1篇
排序方式: 共有203条查询结果,搜索用时 31 毫秒
171.
This study aimed to investigate the impact of contamination by persistent organic pollutants (POPs) on Brazilian wildlife. The concentrations of certain POPs, including dichlorodiphenyltrichloroethane (DDT) and polychlorinated biphenyls (PCBs), in the eggs of the brown booby (Sula leucogaster) were measured. The eggs were collected from breeding colonies located on three archipelagos (Saint Peter and Saint Paul, Abrolhos and Cagarras Islands) in the Atlantic Ocean, which are located at different distances from the Brazilian coast (range 4-1010 km). In addition, possible alterations in eggshell characteristics were evaluated. The average values of POPs found in eggs from the archipelago of Saint Peter and Saint Paul (0.05 μg g−1 of ΣPCBs and 0.01 μg g−1 of ΣDDT) and the archipelago of Abrolhos (0.19 μg g−1 of ΣPCBs and 0.03 μg g−1 of ΣDDT) were low compared to the reference values reported in the literature. In contrast, the concentrations measured in eggs from Cagarras (8.4 μg g−1 of ΣPCBs and 1.8 μg g−1 of ΣDDT) were the highest, and this total PCB level is close to the threshold values considered to be harmful to birds. Our findings indicate that the brown booby colony closest to the Rio de Janeiro coast has recently been exposed to DDT. Despite the high pollution levels found on the Cagarras Islands, no alterations in the eggshell weight or the thickness of the analyzed eggs were detected. Hence, more detailed studies are recommended to determine the actual effects of the selected POPs on the Cagarras breeding colony.  相似文献   
172.
Soil and sediment samples from James Ross Island were analyzed for their PCB, OCP and PAH contents. Soil concentrations ranged between 0.51 and 1.82 ng g(-1) for seven indicator PCB congeners, between 0.49 and 1.34 ng g(-1) for HCH congeners, between 0.51 and 3.68 ng g(-1) for the sum of p,p'-DDT, DDE, and DDD, and between 34.9 and 171 ng g(-1) for the sum of 16 EPA PAHs. Sediment levels from 0.32 to 0.83 ng g(-1) were found for PCBs, from 0.14 to 0.76 ng g(-1) for HCHs, from 0.19 to 1.15 ng g(-1) for DDTs, and from 1.4 to 205 ng g(-1) for PAHs. A prevalence of low-mass PAHs, less chlorinated PCBs, and more volatile chemicals indicates that the long-range atmospheric transport from populated areas of Africa, South America, and Australia is the most probable contamination source for the solid matrices in James Ross Island.  相似文献   
173.
The fishing industry is responsible for generating large amounts of organic waste rich in compounds of commercial interest. This review aimed to present the state of the art about the possibilities of using solid waste to obtain value-added products. Skins, fins, and scales have been used to obtain gelatin and collagen, a promising compound for use as an additive in yogurts and creams, as well as for the synthesis of biodegradable packaging that, if applicable, can reduce the environmental impact caused by petroleum packaging. Other parts, such as the head and the viscera, contain polyunsaturated fatty acids and other fat-soluble vitamins that have been studied for the production of omega-3 capsules for the pharmaceutical industry, but when the extracted oil does not fit the feeding parameters, it can be applied for the production of biodiesel. Furthermore, fishes are a promising source of astaxanthin, a carotenoid with high antioxidant properties. The use of combined techniques such as chemical and enzymatic methods can increase the extraction yield and favor the obtaining of more purified compounds, in addition to promoting the reduction of chemicals that are aggressive to the environment. In general, conscious production in the fishing industry through the valorization of waste generated for use as inputs for other value chains encompasses aspects of the circular economy, which can positively impact several Sustainable Development Goals.  相似文献   
174.
175.
At MayarÕ zone, northeast Cuba, important lateritic deposits have been exploited since 1943. The mineral is used as raw material in a nickel-processing plant which discharges its untreated solid and liquid wastes into Levisa Bay. Similarly to the adjacent Nipe and Cabonico bays, fluvial currents from the mining areas convey a significant mineral load into this bay. To assess the environmental impact caused by the mining and the metallurgical activities, the distribution of Ni, Co, Fe, Mn, Cu, Pb and Zn was investigated in surface and core sediment samples. Uni- and multivariate statistical methods as well as different indices and pollutant factors were used to interpret results. These revealed significant environmental impacts in some areas of the three bays with high concentrations of Ni, Co, Fe and Mn, whose values are up to two orders of magnitude greater than the zone baseline levels. The metal concentrations decreased with increasing distance from discharges. A comparison with other Cuban bays and coastal zones, confirmed that the main source of metal pollution in these three bays was not urban and industrial activities, but lateritic mining and metallurgy.  相似文献   
176.
Oxygen consumption rate was measured as a function of swimming velocity for the vertically migrating euphausiid Euphausia pacifica at two temperatures (8° and 12°C) and pressures (1 and 40 atm) typical of its bathymetric distribution. Increased swimming speed (x; mh-1) required increased oxygen consumption (y; μl O2 mg dry weight-1 h-1), described by the equation y = 0.012x + 0.64 at 8°C, and by y = 0.020x + 0.85 at 12° C. The current concept of low swimming costs of zooplankton, based on determinations of dead drag in copepods, is contradicted by our measurements. Temperature had a more profound effect on metabolism at higher swimming speeds (112 m h-1; Q10=2.8) than on standard metabolism (O m h-1; Q10=2.0), indicating that activity is more costly at higher temperatures. Pressure caused a small but significant (P>0.05) rise in the relationship of respiratory rate to swimming speed at both temperatures. The energy cost of vertical migration for E. pacifica was estimated by applying our data on oxygen consumption vs swimming speed to published observations on sonic scattering layer movement and the day-night distribution pattern of this species. Results indicate that the cost of a diel migration of 254 m, through a temperature change of 4 °C (8° to 12° C), would cancel any energetic benefit gained by time spent at the lower temperature typical of daytime depth. The act of vertical migration is energetically expensive; its cost should be thoroughly considered in attempts to describe the energetics of vertically migrating species.  相似文献   
177.
The value of determination of maternal serum of alpha-fetoprotein (MSAFP) concentration in i he second trimester is well established. In addition to open neural tube defects, pregnancies associated with elevated second-trimester MSAFP have been shown to be at increased risk for a variety of problems, including low birth weight, preterm delivery, and pregnancy-induced hypertension (PIH). We evaluated the potential usefulness of MSAFP in the early third trimester. MSAFP concentration was determined in over 200 women at the time of glucose screening. Results were analysed with regard to gestational age at sampling, maternal weight, race, diabetes, and presence of twins. MSAFP was twice as high in twin gestation, but not affected by race or the presence of diabetes. In contrast to levels in early gestation, third-trimester MSAFP does not appear to be predictive of preterm delivery, low birth weight, or PIH.  相似文献   
178.
Measurements of carbonyls in a 13-story building   总被引:1,自引:0,他引:1  
BACKGROUND, AIM AND SCOPE: Formaldehyde and acetaldehyde are emitted by many mobile and stationary sources and secondary aldehydes are intermediates in the photo-oxidation of organic compounds in the atmosphere. These aldehydes are emitted indoors by many materials such as furniture, carpets, heating and cooling systems, an by smoking. Carbonyls, mainly formaldehyde and acetaldehyde, have been studied because of their adverse health effects. In addition, formaldehyde is a suspected carcinogen. Therefore, the concentrations of formaldehyde and acetaldehyde were determined to assess the inhalation exposure doses to carbonyls for people who work in a 13-story building and in order to evaluate the cancer hazard. METHODS: Carbonyl compounds in indoor and outdoor air were measured at a 13-story building located in Mexico City. The mezzanine, fifth and tenth floors, and the third level-parking garage were selected for sampling. Samples were collected in two sampling periods, the first from April 20 to 29, 1998 and the second from December 1 to 20, 1998. Carbonyls were sampled by means of DNHP-coated cartridges at a flow rate of 1 l min(-1) from 9:00 to 19:00 hours, during 2-hour time intervals and analyzed by HPLC with hours, during 2-hour time intervals and analyzed by HPLC with UV/VIS detection. RESULTS: Mean carbonyl concentrations were highest in the 3rd level-parking garage, with the formaldehyde concentration being the highest ranging from 108 to 418 microg m(-3). In working areas, the highest carbonyl arithmetic mean concentrations (AM) were observed on the 5th floor. Acetone and formaldehyde concentrations were highest in April ranging from 161 to 348 microg m(-3) (AM = 226) and from 157 to 270 microg m(-3) (AM = 221), respectively. Propionaldehyde and butyraldehyde were present in smaller concentrations ranging from 2 to 25 and 1 to 28 microg m(-3), respectively, considering all the samples. Mean indoor/outdoor ratios of carbonyls ranged from 1.8 to 9.6. A reduction of inhalation exposure doses of 41% and 45% was observed in the fifth floor air after the air conditioning systems had been repaired. Formaldehyde and acetaldehyde concentrations were higher in smoking environments. CONCLUSION: Indoor carbonyl concentrations were significantly greater than outdoor concentrations. Tobacco smoke seems to be the main indoor source of formaldehyde. After the air conditioning system was maintained and repaired (as was recommended), an important reduction in the emission of formaldehyde and acetaldehyde was achieved on all floors, except for the 3rd level parking garage, thereby reducing the inhalation exposure doses. RECOMMENDATION: The results obtained in this research demonstrated that maintenance of air conditioning systems must be carried out regularly in order to avoid possible adverse effects on health. Additionally, it is mandatory that isolated smoking areas, with air extraction systems, be installed in every public building.  相似文献   
179.
The potential of the photocatalytic oxidation to selectively oxidise steroid estrogens, β-estradiol and 17α-ethynylestradiol, in the presence of saccharose and ethanol as co-pollutants was clearly demonstrated. The alkaline media conditions remained the most beneficial for the PCO regardless the presence of co-pollutants under consideration. Saccharose appeared to be the more powerful competitor than ethanol. The influence of the co-pollutants is explained by their competition for the adsorption sites and also scavenging of the OH-radicals.  相似文献   
180.
The concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dioxin-like polychlorinated biphenyls (dl-PCBs) and polybrominated diphenylethers (PBDEs) in 33 breast milk samples collected in 2006-2007 from primipara mothers close to four industrial areas of Slovak Republic were determined. The total PCDDs/PCDFs and dl-PCBs expressed as TEQ based on WHO TEFs 1998 in breast milk samples varied from 5.0 to 51.8 pg g−1 fat (median: 13.1 pg g−1 fat; mean: 18.0 pg g−1 fat). The measurements of seven PBDE congeners (IUPAC No. 28, 47, 99, 100, 153, 154, and 183) were performed for the first time in human milk from Slovakia. PBDE levels ranged between 0.22 and 1.62 ng g−1 fat, with median and mean value of 0.43 ng g−1 fat and 0.57 ng g−1 fat respectively. No statistically significant differences were observed between studied areas in total PBDE concentrations.Furthermore, this study presents first results concerning the daily intake (DI) of PCDDs/PCDFs and dioxin-like compounds for the most vulnerable breast-fed infant population in Slovakia. The total PCDD/PCDF and dl-PCB DI for an infant during the first 2 months of life was estimated in a range from 14.4 to 230 pg TEQ kg−1 b.w., with a median value of 58.9 pg TEQ kg−1 b.w.. The DI values substantially exceeded the tolerable daily intake (TDI) 1-4 pg TEQ kg−1 b.w. recommended by WHO. The dietary infant intake concerning PBDEs was estimated to be between 0.69 and 7.1 ng kg−1 b.w. d−1, with median value of 1.7 ng kg−1 b.w. d−1.  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