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   163篇
  免费   5篇
  国内免费   3篇
安全科学   8篇
废物处理   10篇
环保管理   18篇
综合类   25篇
基础理论   34篇
污染及防治   56篇
评价与监测   7篇
社会与环境   10篇
灾害及防治   3篇
  2022年   2篇
  2021年   10篇
  2020年   4篇
  2019年   4篇
  2018年   2篇
  2017年   6篇
  2016年   5篇
  2015年   2篇
  2014年   4篇
  2013年   20篇
  2012年   3篇
  2011年   12篇
  2010年   5篇
  2009年   7篇
  2008年   8篇
  2007年   11篇
  2006年   10篇
  2005年   5篇
  2004年   1篇
  2002年   6篇
  2001年   9篇
  2000年   1篇
  1999年   3篇
  1998年   1篇
  1997年   1篇
  1996年   1篇
  1995年   4篇
  1994年   1篇
  1993年   1篇
  1992年   4篇
  1991年   1篇
  1990年   2篇
  1989年   2篇
  1988年   1篇
  1987年   1篇
  1982年   1篇
  1980年   1篇
  1979年   1篇
  1978年   2篇
  1976年   1篇
  1974年   1篇
  1966年   2篇
  1963年   1篇
  1960年   1篇
排序方式: 共有171条查询结果,搜索用时 15 毫秒
141.
Environment, Development and Sustainability - The variation in the atmospheric conditions of urban areas to the fringe areas is termed as urban heat island and is attributed predominantly to the...  相似文献   
142.
Natural steroid estrogens (e.g., 17 β-estradiol, E2), synthetic steroid estrogens (e.g., 17 α-ethinylestradiol, EE2) and pharmaceutical antibiotics (e.g., ciprofloxacin) are chemicals detected in biosolids and sewage sludges because they partition into the solids fraction during the wastewater treatment process. This research utilized a three-way factorial design (six media × two estrogens × three antibiotic treatments) to quantify cumulative E2 and EE2 mineralization over 133 d (MAX) in a range of sewage sludge and biosolid samples in the presence (4 and 40 mg kg?1) and absence of ciprofloxacin. The same three-way factorial design was utilized to quantify the impact of the six media, E2 or EE2, and ciprofloxacin on cumulative soil respiration over 133 d (RESP). Minimal ciprofloxacin mineralization was observed (<0.05% over 133 d), but despite its persistence, ciprofloxacin had no significant effect on MAX of E2 or EE2, and, in general, no significant effect on RESP. MAX ranged from 38.38% to 48.44% for E2 but from only 0.72% to 24.27% for EE2 although RESP was relatively similar, ranging from 101.00 to 866.54 mg CO2 in the presence of E2 and from 69.55 to 893.95 mg CO2 in the presence of EE2. The sorption-limited bioavailability of EE2, which is inherently resistant to biodegradation due to chemical structure, as MAX and Freundlich sorption coefficients (Kf) were negatively correlated. As such, the Kf values of EE2 were largest in composted biosolids in which EE2 was particularly resistant to microbial degradation as the MAX of EE2 was <3%. In contrast, the MAX of E2 showed a positive association with the Kf values of E2 because some steps in the E2 transformation process have been found to occur in the sorbed phase. The MAX of E2 was significantly greater in the biosolid and composted biosolid media than in any other media, whereas the MAX of E2 decreased in the following order: secondary sewage sludge > primary sewage sludge > biosolid = composted biosolid. This suggests that sewage sludges in municipal lagoons and pre-treatment holding lagoons are a more favorable media for mineralization of EE2, whereas biosolids in post-treatment storage lagoons are a more favorable media for the mineralization of E2. The presence of ciprofloxacin will have no impact on the potential E2 or EE2 mineralization rates in these cases.  相似文献   
143.
144.
145.
146.
Sediment cores taken from the deep basin of Loch Coire nan Arr in north-west Scotland were dated using 210Pb calibrated spheroidal carbonaceous particle (SCP) profiles and analysed for trace metals, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). These data show that the site is one of the least contaminated by atmospheric pollution in the UK. Peak concentrations of PAHs were found to be equivalent to background values at sites in the English Lake District. The date of concentration maxima for SCP, PCB and some metals were in agreement with previously published polychlorinated dibenzo-p-dioxin/polychlorinated dibenzofuran (PCDD/F) data suggesting long-range industrial sources. The date of individual PAH concentration maxima were earlier, but concomitant with each other, possibly suggesting the influence of a local source. Comparison with remote European mountain lakes shows Loch Coire nan Arr to be one of the least contaminated sites in Europe with respect to PCBs, but more contaminated with respect to PAHs.  相似文献   
147.
Conservation practitioners must contend with an increasing array of threats that affect biodiversity. Citizen scientists can provide timely and expansive information for addressing these threats across large scales, but their data may contain sampling biases. We used randomization procedures to account for possible sampling biases in opportunistically reported citizen science data to identify species’ sensitivities to human land use. We analyzed 21,044 records of 143 native reptile and amphibian species reported to the Carolina Herp Atlas from North Carolina and South Carolina between 1 January 1990 and 12 July 2014. Sensitive species significantly associated with natural landscapes were 3.4 times more likely to be legally protected or treated as of conservation concern by state resource agencies than less sensitive species significantly associated with human‐dominated landscapes. Many of the species significantly associated with natural landscapes occurred primarily in habitats that had been nearly eradicated or otherwise altered in the Carolinas, including isolated wetlands, longleaf pine savannas, and Appalachian forests. Rare species with few reports were more likely to be associated with natural landscapes and 3.2 times more likely to be legally protected or treated as of conservation concern than species with at least 20 reported occurrences. Our results suggest that opportunistically reported citizen science data can be used to identify sensitive species and that species currently restricted primarily to natural landscapes are likely at greatest risk of decline from future losses of natural habitat. Our approach demonstrates the usefulness of citizen science data in prioritizing conservation and in helping practitioners address species declines and extinctions at large extents.  相似文献   
148.
Both a cross-sectional and a longitudinal study were performed to investigate whether or not the collection time should be taken into consideration when generating a patient's risk for fetal Down syndrome with multiple marker screening. Diurnal variations of third-trimester alpha-fetoprotein (AFP) levels and first-trimester human chorionic gonadotropin (hCG) levels have been previously reported. In addition, large episodic fluctuations of conjugated and unconjugated oestriol (uE3) as well as a diurnal variation have also been reported in the third trimester. If the levels of these analytes routinely fluctuate during the day, they could affect a patient's risk calculation for fetal Down syndrome. The longitudinal study evaluated ten non-diabetic women who underwent sequential sampling for AFP, hCG, and uE3. The cross-sectional study evaluated 1953 patients for these three markers whose time of sampling was recorded between 8·00 a.m. and 5·59 p.m. Using either study design, no significant effect was seen in the median MOM levels of the screening analytes as a function of the time of day.  相似文献   
149.
This paper formulates an input-output method for determining the distributional consequences of energy development projects. The method is oriented to the conditions appearing in many contemporary development settings where large resident populations and other factors are likely to inhibit boomtown scenarios. An analysis of geothermal energy development in Imperial County, California, is presented. The results indicate that personal income inequality is likely to increase by several percentage points as measured by the Gini coefficient. The sensitivity of the results is examined with respect to important factors such as labor supply elasticities, preferential employment of local residents, and the concentration of land holdings.  相似文献   
150.
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