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   511篇
  免费   4篇
  国内免费   11篇
安全科学   21篇
废物处理   21篇
环保管理   75篇
综合类   89篇
基础理论   72篇
污染及防治   153篇
评价与监测   50篇
社会与环境   38篇
灾害及防治   7篇
  2023年   8篇
  2022年   23篇
  2021年   26篇
  2020年   12篇
  2019年   7篇
  2018年   15篇
  2017年   15篇
  2016年   10篇
  2015年   12篇
  2014年   21篇
  2013年   52篇
  2012年   19篇
  2011年   36篇
  2010年   23篇
  2009年   26篇
  2008年   26篇
  2007年   24篇
  2006年   22篇
  2005年   18篇
  2004年   10篇
  2003年   15篇
  2002年   7篇
  2001年   5篇
  2000年   5篇
  1999年   6篇
  1998年   4篇
  1997年   4篇
  1996年   4篇
  1994年   6篇
  1993年   5篇
  1992年   5篇
  1990年   5篇
  1989年   5篇
  1987年   2篇
  1986年   4篇
  1985年   2篇
  1982年   4篇
  1973年   2篇
  1955年   2篇
  1933年   1篇
  1931年   2篇
  1926年   2篇
  1924年   2篇
  1923年   1篇
  1920年   3篇
  1919年   1篇
  1917年   2篇
  1916年   3篇
  1914年   1篇
  1913年   1篇
排序方式: 共有526条查询结果,搜索用时 15 毫秒
91.
Time of departure and landing of nocturnal migrants are of great importance for understanding migratory strategy used by birds. It allows us to estimate flying time and hence the distance that migrants cover during a single night. In this paper, I studied the temporal schedule of nocturnal departures of European robins during spring migration. The study was done on the Courish Spit on the Baltic Sea in 1998–2003 by retrapping 51 ringed birds in high mist nets during nocturnal migratory departure. Take-offs of individual birds occurred between the first and tenth hour after sunset (median 176 min after sunset). Departure time was not related to fuel stores at arrival and departure, stopover duration and progress of the season. The results suggest that one reason for temporal variation in take-off time was differential response of European robins with high and low motivation to depart to such triggers as air pressure and its trend. If these parameters reach a certain minimum threshold shortly before sunset, robins with a high migratory motivation take off in the beginning of the night. When air pressure or its trend reaches a maximum, it may trigger to take off later during the night birds with lower initial motivation for departure, including those that have low refuelling efficiency. In regulation of timing of take-offs of robins, an important role is also played by their individual endogenous circadian rhythm of activity which is related to the environment in a complex way.  相似文献   
92.
Johansson V  Ranius T  Snäll T 《Ecology》2012,93(2):235-241
The colonization-extinction dynamics of many species are affected by the dynamics of their patches. For increasing our understanding of the metapopulation dynamics of sessile species confined to dynamic patches, we fitted a Bayesian incidence function model extended for dynamic landscapes to snapshot data on five epiphytic lichens among 2083 mapped oaks (dynamic patches). We estimate the age at which trees become suitable patches for different species, which defines their niche breadth (number of suitable trees). We show that the colonization rates were generally low, but increased with increasing connectivity in accordance with metapopulation theory. The rates were related to species traits, and we show, for the first time, that they are higher for species with wide niches and small dispersal propagules than for species with narrow niches or large propagules. We also show frequent long-distance dispersal in epiphytes by quantifying the relative importance of local dispersal and background deposition of dispersal propagules. Local stochastic extinctions from intact trees were negligible in all study species, and thus, the extinction rate is set by the rate of patch destruction (tree fall). These findings mean that epiphyte metapopulations may have slow colonization-extinction dynamics that are explained by connectivity, species traits, and patch dynamics.  相似文献   
93.
Developing renewable energy is now becoming a hot topic as it is important in dealing with climate change issue and energy supply issue. With the growing demand of energy, it has become urgent to develop the effective policies and measures that would enable people to maintain the living standards. Among all the measures, price is an essential one. In order to evaluate the costs and prices of the electricity from renewable energy sources (RES-E) and their effects to the market, this paper firstly focus on the extra costs of the RES-E by breaking it into four parts, including investment, construction, connection and operation. Then, the policy choices made in some typical industrialized countries are examined to find answers to the problems RES-E can raise. Finally, the choices made in China are examined in comparison to industrialized countries so as to determine how the current situation could be improved.  相似文献   
94.
In Portugal, due to the combination of climatological and ecological factors, large wildfires are a constant threat and due to their economic impact, a big policy issue. In order to organize efficient fire fighting capacity and resource management, correct quantification of the risk of large wildfires are needed. In this paper, we quantify the regional risk of large wildfire sizes, by fitting a Generalized Pareto distribution to excesses over a suitably chosen high threshold. Spatio-temporal variations are introduced into the model through model parameters with suitably chosen link functions. The inference on these models are carried using Bayesian Hierarchical Models and Markov chain Monte Carlo methods.  相似文献   
95.
Small-scale geographical variation in the occurrence of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) was investigated using the eggs of a terrestrial residential songbird species, the great tit (Parus major). In addition, we investigated the influence of the type of sampling location on the presence of these pollutants. To achieve this, 10 different sampling locations in Flanders (Belgium) were classified into 3 groups based on the extent of urbanisation, industrialisation and agriculture. The higher variance among sampling locations for the levels and profiles of PCBs and OCPs, suggests that local contamination sources are more important for the PCBs and OCPs compared to the PBDEs. Levels of PCBs and PBDEs were significantly higher in the industrialised sampling locations compared to the other locations. Sum PCB and sum PBDE levels reached up to 6050 and 79 ng/g lipid weight, respectively. PCBs and PBDEs were highly positively correlated for all groups, suggesting similar exposure pathways and/or mechanisms of accumulation. Significantly higher levels of OCPs (sum OCPs up to 2683 ng/g lipid weight) were detected in the rural sampling locations situated in a residential area. This suggests that local historical usage of OCPs by inhabitants may be an important source of contamination in Flanders. Contamination profiles differed also among the sampling locations. The rural sampling locations had a higher contribution of lower brominated BDE congeners, whereas the industrialised locations had a higher contribution of higher brominated congeners. The differences in contamination profiles among the sampling locations are probably due to differences in exposure. In conclusion, our results showed that the characteristics of a sampling location influence both the levels and profiles of PCBs, OCPs and PBDEs.  相似文献   
96.
We investigated the possible sources of contamination with organic pollutants, such as polychlorinated biphenyls (PCBs), p,p'-dichlorodiphenyltrichloroethane (DDT) and metabolites, and polybrominated diphenyl ethers (PBDEs), in and onto tail feathers of a large songbird, the common magpie (Pica pica). Although feathers are potentially useful as a non-destructive biomonitor for organic pollutants, concentrations may be influenced by external contamination onto the feather surface. In a first approach, a group of magpies was captured after the completion of moult. The third tail feather was pulled out and a blood sample was taken. Most PCBs, DDTs and some PBDEs could be quantified in one single tail feather, indicating that the applicability of feathers goes beyond monitoring with predatory birds, as shown previously. Nevertheless, correlations between levels in serum and feathers were found significant in three cases only (i.e. CB 170, CB 180 and CB 187). This finding may be attributed to different factors, such as varying diet, condition, sample size or external contamination. In a second approach, cadavers of magpies were collected throughout Flanders. The preen gland was removed and the first, third and fifth tail feathers were pulled out at both sides. No significant differences were found among tail feathers within an individual. We compared three washing procedures to remove external contamination with organic pollutants from these feathers: deionised water, acetone and a surfactant/acetone solution. Right feathers were washed and left feathers were kept as control. Concentrations in the resulting washes were found highest in the acetone solutions. Furthermore, feathers washed with acetone or with a surfactant/acetone solution had significantly lower mean concentrations than the control feathers. Highest correlations with levels in preen gland were obtained for the control feathers. Consequently, the source of external contamination with organic pollutants onto feathers seems to be endogenous, originating from the preen gland. This is in great contrast to the extensive airborne pollution that has been reported for most heavy metals. In summary, the results of the current study highlight the usefulness of feathers for non-destructive biomonitoring of organic pollutants.  相似文献   
97.
ABSTRACT

Scholars and practitioners have focused in recent years on the potential for achieving cooperation in small “clubs” of countries. While solutions to global climate change will eventually require widespread cooperation, club strategies could help to catalyze that outcome. Unlike the Paris Agreement, which has achieved widespread but relatively shallow cooperation, it could be easier to tailor agreements that allow deep cooperation within smaller groups. This essay extends that logic to clubs whose geometry varies two-dimensionally across countries but also along a third dimension: within countries. Most of the key elements of international relations and international law theory that explain how clubs achieve cooperation are directly applicable to three-dimensional clubs. Most of the relevant experience for these clubs has occurred in the west; overdue is a close assessment of how key units – such as provinces and firms – within China and other emerging economies.  相似文献   
98.
In this article, we apply count-data travel-cost methods to a truncated sample of visitors to estimate the Peneda-Gerês National Park (PGNP) average consumer surplus (CS) for each day of visit. The measurement of recreation demand is highly specific because it is calculated by number of days of stay per visit. We therefore propose the application of altered truncated count-data models or truncated count-data models on grouped data to estimate a single, on-site individual recreation demand function, with the price (cost) of each recreation day per trip equal to out-of-pocket and time travel plus out-of-pocket and on-site time costs. We further check the sensitivity of coefficient estimations to alternative models and analyse the welfare measure precision by using the delta and simulation methods by Creel and Loomis. With simulated limits, CS is estimated to be €194 (range €116 to €448). This information is of use in the quest to improve government policy and PNPG management and conservation as well as promote nature-based tourism. To our knowledge, this is the first attempt to measure the average recreation net benefits of each day of stay generated by a national park by using truncated altered and truncated grouped count-data travel-cost models based on observing the individual number of days of stay.  相似文献   
99.
Environmental Science and Pollution Research - Water is considered one of the most superabundant resources on the earth that covers 75% of the entire earth’s surface, yet numerous countries...  相似文献   
100.
Environmental Science and Pollution Research - The growing demand for products with lower environmental impact and the extensive applicability of cellulose nanofibrils (CNFs) have received...  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