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   500篇
  免费   2篇
  国内免费   9篇
安全科学   16篇
废物处理   23篇
环保管理   50篇
综合类   116篇
基础理论   83篇
污染及防治   162篇
评价与监测   42篇
社会与环境   17篇
灾害及防治   2篇
  2023年   4篇
  2022年   11篇
  2021年   10篇
  2020年   2篇
  2019年   6篇
  2018年   7篇
  2017年   9篇
  2016年   27篇
  2015年   12篇
  2014年   24篇
  2013年   35篇
  2012年   27篇
  2011年   32篇
  2010年   36篇
  2009年   23篇
  2008年   24篇
  2007年   31篇
  2006年   26篇
  2005年   25篇
  2004年   27篇
  2003年   8篇
  2002年   7篇
  2001年   5篇
  2000年   7篇
  1999年   5篇
  1997年   3篇
  1994年   5篇
  1993年   5篇
  1992年   3篇
  1989年   3篇
  1988年   3篇
  1987年   5篇
  1986年   2篇
  1985年   4篇
  1984年   5篇
  1983年   5篇
  1982年   2篇
  1981年   3篇
  1979年   3篇
  1975年   2篇
  1972年   2篇
  1965年   2篇
  1964年   2篇
  1962年   1篇
  1960年   1篇
  1956年   2篇
  1955年   2篇
  1951年   2篇
  1948年   1篇
  1931年   2篇
排序方式: 共有511条查询结果,搜索用时 77 毫秒
241.
The observed high-level burdens of organohalogens among the residents of the Faroe Islands, needs to be explained. Long-finned pilot whale (Globicephala melas) blubber and meat are known sources of environmental exposure. The present study focus on the organohalogen contamination of the fulmar (Fulmarus glacialis). The compounds quantified in fulmar muscle, fat, and egg are PCBs, DDTs, hexachlorobenzene (HCB), and polybrominated diphenyl ethers (PBDEs). The dominating pollutants are the 4,4'-DDT metabolite 4,4'-DDE and the two PCB congeners, CB-153 and CB-180, which are present in geometric mean concentrations of 7100, 4700 and 2500 ng/g lipid weight (l.w.), respectively, in adult fulmar muscle. 4,4'-DDT and HCB concentrations are approximately 250 ng/gl.w., each. Concentrations in the eggs are about 50% of the fulmar muscle levels, due to differences in lipid amounts, 4% in muscle and 10% in the eggs, the exposure contribution on a fresh weight basis is almost the same. As a result, both the egg and the adult fulmar muscle may lead to a significant exposure risk, if consumed by humans. BDE-153, the most abundant PBDE congener in fulmar muscle, with a geometric mean concentration of 6.5 ng/gl.w., is much lower than the individual PCB congeners and 4,4'-DDE concentrations. In the adult fulmar muscle, the relative PBDE congener pattern is different from that previously observed in biota, with BDE-153 and BDE-154 as the dominating congeners, rather than BDE-47. In contrast, BDE-47 is the most abundant congener in juvenile muscle and subcutaneous fat. The summation operatorPBDE concentrations are almost the same in egg, muscle (adult and juvenile) and subcutaneous fat (juvenile). For the polybrominated biphenyl (BB-153) the concentrations are considerably higher in the adult bird and egg than in the juvenile bird; this is also seen for the PCB and 4,4'-DDE concentrations. PCB concentrations found in fulmar egg and muscle are in the same range as seen in the pilot whale, i.e. 590-5700 ng/gl.w. for CB-153. Hence humans are also exposed to PCBs at a reasonable degree via intake of fulmar and/or fulmar egg and not only via pilot whale blubber.  相似文献   
242.
A perfluorooctane sulfonic acid (PFOS) biomonitoring survey was conducted on great tit (Parus major) and blue tit (Parus caeruleus) nestlings from Blokkersdijk, a bird reserve in the proximity of a fluorochemical plant in Antwerp (Belgium) and Fort IV, a control area. PFOS, together with 11 organochlorine pesticides, 20 polychlorinated biphenyl congeners and 7 polybrominated diphenyl ethers were measured in liver tissue. The hepatic PFOS concentrations at Blokkersdijk (86–2788 and 317–3322 ng/g wet weight (ww) for great and blue tit, respectively) were among the highest ever measured and were significantly higher than at the control area (17–206 and 69–514 ng/g ww for great and blue tit, respectively). The hepatic PFOS concentration was species- and sex-independent and correlated significantly and positively with the serum alanine aminotransferase activity and negatively with the serum cholesterol and triglyceride levels in both species but did not correlate with condition or serum protein concentration. In the great tit, a significant positive correlation was observed between the liver PFOS concentration and the relative liver weight. In the blue tit, the hepatic PFOS concentration correlated positively and significantly with hematocrite values. None of the investigated organohalogen pollutants except for PFOS were suggested to be involved in the observed biological alterations.  相似文献   
243.
Temporal airborne bacterial genetic community structure and meteorological factors were analysed above an urban area in the northwest of France from December 2003 to April 2004 with a sampling strategy considering different time intervals (from an hour to a month). Principal component analysis (PCA) of B-ARISA (Bacterial-Automated Ribosomal Intergenic Spacer Analysis) profiles revealed a hierarchy in the temporal variability of bacterial community: daily<weekly<seasonal. Co-inertia analysis between B-ARISA data and meteorological factors demonstrated the correlation between the seasonal variability in the bacterial community and climatic conditions such as temperature and relative humidity, whereas daily and weekly variability seemed likely to be managed by other factors such as anthropogenic activities.  相似文献   
244.
A perfluorooctane sulfonic acid (PFOS) assessment was conducted on gibel carp (Carassius auratus gibelio), carp (Cyprinus carpio), and eel (Anguilla anguilla) in Flanders (Belgium). The liver PFOS concentrations in fish from the Ieperlee canal (Boezinge, 250-9031 ng/g wet weight, respectively) and the Blokkersdijk pond (Antwerp, 633-1822 ng/g wet weight) were higher than at the Zuun basin (Sint-Pieters-Leeuw, 11.2-162 ng/g wet weight) and among the highest in feral fish worldwide. Eel from the Oude Maas pond (Dilsen-Stokkem) and Watersportbaan basin (Ghent) had PFOS concentrations ranging between 212 and 857 ng/g wet weight. The hepatic PFOS concentration was significantly and positively related with the serum alanine aminotransferase activity, and negatively with the serum protein content in eel and carp. The hepatic PFOS concentration in carp correlated significantly and negatively with the serum electrolyte concentrations whereas a significant positive relation was found with the hematocrit in eel. Although 13 organochlorine pesticides, 22 polychlorinated biphenyl (PCB) congeners and 7 polybrominated diphenyl ethers (PBDEs) were also measured in the liver tissue, only PCB 28, PCB 74, gamma-hexachlorocyclohexane (gamma-HCH) and hexachlorobenzene (HCB) were suggested to contribute to the observed serological alterations in eel.  相似文献   
245.
造纸污泥生物炭对四环素的吸附特性及机理   总被引:2,自引:0,他引:2  
以造纸污泥为原料,在限氧条件下,通过控制热解温度(300,500和700℃),制备生物炭(SBC300、SBC500和SBC700),比较了3种生物炭的基本理化性质;以四环素(TC)为目标污染物,研究了造纸污泥生物炭(SBC)对TC的吸附特性及机理.结果表明,SBC对TC的吸附以化学吸附为主,吸附平衡时,SBC300对TC的去除率最低,为38.8%,SBC700的去除率最高,为54.1%;同时Langmuir模型能更好地描述此吸附过程,且最大吸附量依次为SBC700(63.8mg/g) > SBC500(50.6mg/g) > SBC300(40.0mg/g).热力学分析表明,SBC对TC的吸附为自发且吸热的过程.pH值影响TC的存在形态及SBC的表面带电情况,对吸附过程有较大影响.通过吸附等温线分解法定量描述了表面吸附作用及分配作用的贡献率,结合FTIR分析,表明SBC对TC的吸附可能是分配作用、静电作用、氢键作用、π-π EDA作用及离子交换作用等共同作用的结果.  相似文献   
246.
M. E. Huber 《Marine Biology》1987,93(4):509-515
Colonies of Pocillopora spp. containing the crab Trapezia digitalis were collected from Hawaii in summer of 1979 and of 1980. Individuals of T. digitalis in Hawaii vary extensively in coloration of the carapace: crabs were separated into phenotypic classes by their degree of carapace reticulation. When presented with two females of different phenotype, males preferentially paired with the female which was similar to them in reticulation. The genetic population structure of T. digitalis was unusual by comparison with other species of Trapezia. Previously reported homozygote excesses at esterase-4, hexokinase-1, phosphoglucoseisomerase, and general protein-2 cannot be explained by the single-locus Wahlund effect, since there was not significant genetic differentiation among phenotypic classes, as measured by Wright's F ST statistic. There was significant variation among classes in allele frequencies at a fifth locus, hexokinase-2. Two pairs of loci were in significant gametic disequilibrium. Gametic disequilibrium was not detected in seven other species of Trapezia. It is suggested that multi-locus genetic analysis and an increased geographic sampling range are needed to determine the genetic population structure of T. digitalis in relation to observed variation in coloration.  相似文献   
247.
The levels and distribution of PBDEs in zebra mussels and several freshwater fish species (eel, carp and gibel carp) were investigated for different sites in Flanders, Belgium. In parallel, other organohalogenated contaminants, such as polychlorinated biphenyls (PCBs), p,p[prime or minute]-DDE and hexachlorobenzene (HCB) were also measured and their relationship with PBDEs was investigated. At most sites, individual PBDE congeners were present at detectable levels in mussel tissue, with the mean [summation operator]PBDE concentration ranging from 0.15 to 1.8 ng g(-1) wet weight (ww). The PCB concentrations in mussels ranged from 6.2 to 102 ng g(-1) ww. HCB and p,p[prime or minute]-DDE could be measured in mussels from most sites, mean values ranging from below the limit of quantification (LOQ) to 0.58 ng g(-1) ww and from 0.66 to 6.5 ng g(-1) ww, respectively. Except for one site (Blokkersdijk, Antwerp) where PBDEs were below the LOQ in carp muscle, all fish samples from other sites contained detectable PBDE levels, with the highest concentrations (14 +/- 14 ng g(-1) ww) being measured in eel liver from Watersportbaan (Ghent). The sampled sites covered a broad concentration range of organohalogenated pollutants with the highest values being consistently measured in eel liver. With few exceptions, all correlations between PBDEs and organochlorine pollutants for each species were low (r < 0.50) and most were statistically not significant (p > 0.05). This suggests that the exposure to contaminants arises from local sources possessing different signatures of PBDEs and organochlorine pollutants.  相似文献   
248.
Lidar measurements of temperature for the upper troposphere and lower stratosphere are commonly derived by the Raman technique. Lidar signals derived from vibrational Raman processes have been subjected to numerous simulation tests to examine their sensitivity to the presence of aerosols and ozone in the atmosphere. The influence of aerosols characteristics (wavelength dependence of aerosol extinction and particle phase function) and of ozone concentration on Raman temperature profiles is estimated. Simulations indicate large temperature deviations for post-volcanic conditions. For a Raman backscatter at 607 nm, bias is below 1 K for a total optical depth less than 9 x 10(-3) in the case of a stratospheric contamination and less than 6 x 10(-3) for a tropospheric contamination. The effect of aerosols depends on phase function and a few parameters such as altitude, optical depth and the shape of the high-altitude cloud. The wavelength dependence of aerosol extinction has some influence only for severe post-volcanic conditions (Scattering Ratio, SR >2). For a Raman backscatter at 387 nm, bias is larger and can be significant even in background aerosol conditions. Changes in the ozone density profile lead to significant Raman temperature deviations only for some specific conditions. Results suggest that both aerosol and ozone corrections are necessary to obtain an accuracy better than the 1 K requested for most atmospheric applications.  相似文献   
249.
The United States is making the transition from the 1979 1 hr maximum ozone standard to the newly adopted 8 hr ozone standard (3 yr average of the 4th highest maximum 8 hr ozone concentration). Consequently, we analyzed and compared ozone concentrations under both standards from a variety of monitoring sites throughout the central Appalachian region of Kentucky (KY), West Virginia (WV), and Virginia (VA). Data from 1988-1999 were used to determine how ozone exposure between the two metrics compared for remote sites. Most sites exceeded the 1 hr standard in 1988-1990 due to the 3 yr averaging and multiple high ozone concentrations that occurred over the region in 1988. All sites were in compliance with the 1 hr standard every year after 1991. It was much more common for the ozone exposure to exceed the 8 hr standard, particularly from 1997-1999. Many sites showed exceedences beginning in 1995; Big Meadows (VA) exceeded the 8 hr standard all years except 1994 and 1996. Response of vegetation to ozone in these areas was determined using the combination of W126 values (sigmoidally weighted exposure index), the number of hours that average concentrations > or = 0.10 ppm (N100), and the presence of moderate or more extreme droughts. In general, W126 and N100 values suggested that negative vegetation growth responses over most of the 12 yr would have been minimal for most sites, even for those exceeding ozone standards. Drought-induced stomatal closures would have overridden more extreme negative growth responses at all but the Big Meadows site in 1988.  相似文献   
250.
Urban lakes provide many ecosystem services, e.g., flood control, nature protection, coolness island, recreation. Hydrodynamic models will increasingly be used to enhance these benefits. We present the first validation of a three-dimensional (3D) hydrodynamic model on a small shallow lake with high resolution and high frequency measurements. Lake Créteil, France (area 0.4 km2, mean depth 4.5 m, and catchment area 1 km2) is a former gravel pit and now part of a regional park. The model Delft3D-FLOW was calibrated on a one-month period, with continuous measurements of temperature at five depths at the center of the lake and at three depths at two other stations, and with current speed profiles at the centre of the lake. The model was then verified on 18 1-month periods with similar temperature measurements. The model reproduced very well the temperature dynamics, including the alternation between mixing and stratification periods and internal wave patterns. The mean absolute errors over the five depths at the central point remained below 0.55°C in spring and summer, the most favorable seasons for phytoplankton growth. Horizontal temperature differences, which rose up to 3°C at the beginning of stratification periods, were also well reproduced, as well as current speeds. These results are very promising for assessing nutrient and pollutant diffusion, settling and resuspension, as well as for understanding how phytoplankton blooms start in small shallow lakes.  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