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   169篇
  免费   7篇
  国内免费   20篇
安全科学   17篇
环保管理   11篇
综合类   37篇
基础理论   74篇
污染及防治   9篇
评价与监测   6篇
社会与环境   14篇
灾害及防治   28篇
  2024年   1篇
  2023年   1篇
  2022年   3篇
  2021年   4篇
  2020年   5篇
  2019年   7篇
  2018年   4篇
  2017年   5篇
  2016年   13篇
  2015年   3篇
  2014年   2篇
  2013年   21篇
  2012年   6篇
  2011年   11篇
  2010年   17篇
  2009年   11篇
  2008年   7篇
  2007年   10篇
  2006年   12篇
  2005年   5篇
  2004年   11篇
  2003年   3篇
  2002年   7篇
  2001年   5篇
  2000年   4篇
  1999年   4篇
  1998年   3篇
  1997年   2篇
  1996年   2篇
  1995年   1篇
  1994年   3篇
  1993年   1篇
  1988年   1篇
  1982年   1篇
排序方式: 共有196条查询结果,搜索用时 62 毫秒
81.
Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) is a serious pest of corn in several American countries. It is mainly controlled with synthetic insecticides. The objectives of this study were to evaluate the effects of the natural products, neem oil and pyroligneous extract, and the synthetic insecticide, lufenuron, at 2.50mL water (0.25 %) on the mortality of 2-, 4- and 6-day-old caterpillars of S. frugiperda, and their selectivities against fourth instar larvae of Eriopis connnexa Germar (Coleoptera: Coccinellidae). Four- and 6-day-old S. frugiperda caterpillars showed higher mortality after exposure to neem oil (83.33 ± 0.83 and 89.58 ± 0.90 %, respectively) and lufenuron (95.83 ± 0.96 and 85.41 ± 0.83 %), compared to pyroligneous extract (68.75 ± 0.69 and 31.25 ± 0.31 %). The deleterious effect of pyroligneous extract was higher in 2- (83.33 ± 0.83 % mortality) and 4-day-old (68.75 ± 0.69 %) S. frugiperda caterpillars than in 6-day-old caterpillars (31.25 ± 0.31 %). Larval mortality of the predator E. connexa was lower with neem oil and pyroligneous extract (25.00 ± 0.33 %) than with lufenuron (91.66 ± 1.22 %). Neem oil is thus recommended for control of S. frugiperda because of its high toxicity, combined with its relatively low toxicity to larvae of the natural enemy E. connexa.  相似文献   
82.
Globally, policies aiming for conservation of species, free-flowing rivers, and promotion of hydroelectricity as renewable energy and as a means to decarbonize energy systems generate trade-offs between protecting freshwater fauna and development of hydropower. Hydroelectric turbines put fish at risk of severe injury during passage. Therefore, comprehensive, reliable analyses of turbine-induced fish mortality are pivotal to support an informed debate on the sustainability of hydropower (i.e., how much a society is willing to pay in terms of costs incurred on rivers and their biota). We compiled and examined a comprehensive, global data set of turbine fish-mortality assessments involving >275,000 individual fish of 75 species to estimate mortality across turbine types and fish species. Average fish mortality from hydroelectric turbines was 22.3% (95% CI 17.5–26.7%) when accounting for common uncertainties related to empirical estimates (e.g., handling- or catch-related effects). Mortality estimates were highly variable among and within different turbine types, study methods, and taxa. Technical configurations of hydroelectric turbines that successfully reduce fish mortality and fish-protective hydropower operation as a global standard could balance the need for renewable energy with protection of fish biodiversity.  相似文献   
83.
In a previous paper, we reported that juvenile barn swallows (Hirundo rustica) trapped during the autumn migratory season and tested in modified Emlen funnels under overcast conditions can use magnetic information for compass orientation, although they did not orient toward the expected migratory direction. To further investigate this behaviour, in the present paper, we report the results of two series of displacement experiments performed on juvenile barn swallows belonging to two different roost sites [Massaciuccoli Lake (ML) and Terzo Cavone (TC)] and tested using the same protocol as that previously adopted. On the whole, the outcome of the ML and TC experiments was quite different with respect to (a) the degree of bird activity within the funnel (substantially lower for TC) and (b) the effect of the experimental displacement on the directional preferences of the tested subjects (not detectable in TC, while evident in ML swallows). Taken together, these results suggest that migrating swallows could react differently to the experimental tests depending on the roost site where they were caught. Indeed, TC swallows, trapped in southern Italy, close to the seacoast, and characterized by fairly large amounts of fat stores, mainly broke off their migratory activity or reoriented their directional preferences toward inland sites, possibly in search of more profitable habitats. On the other hand, ML swallows, trapped about 660 km to the north and characterized by lower amounts of fat stores, apparently tried to compensate for the experimental displacement.
N. Emilio BaldacciniEmail:
  相似文献   
84.
The interactions between cod (Gadus morhua), herring (Clupea harengus) and sprat (Sprattus sprattus) in the Central Baltic Sea were examined with a simple dynamic model, an alternative to more complicated and data-demanding multispecies and ecosystem models. The main aims of the study were to compare the effect of alternative structures on the model output and examine the control relationships in the fish assemblage under different environmental conditions. The effect of environmental conditions was modelled using a stock-recruitment equation for cod incorporating an environmental index. The model output was especially sensitive to the functional response in predation by cod on herring and sprat. The type II functional response led to a collapse of the clupeid stocks when cod was abundant, while the type III response produced more realistic stock dynamics. According to the simulations, an abundant cod stock was able to keep the sprat stock at a low level, while the herring stock was less affected and benefited from the decreased density of sprat. Simulation of different fishing scenarios indicated that reducing fishing mortality to the level currently advised by ICES would allow the recovery of the cod stock even in unfavourable environmental conditions.  相似文献   
85.
86.
为了评估PM2.5排放导致女性生殖系统癌症的风险以及城乡差异,以卵巢癌为例,分析了中国东部地区2000~2011年期间PM2.5和卵巢癌发病率和死亡率的相关关系,并估算了PM2.5排放导致卵巢癌发病率和死亡率升高的风险.结果表明,城市地区卵巢癌发病率和死亡率显著高于农村,在城市地区,PM2.5与卵巢癌发病率显著相关,PM2.5年平均浓度每上升10μg/m3,城市地区卵巢癌发病率上升的相对风险为9.3%(相对于PM2.5年平均浓度为35μg/m3时),每十万人口升高0.51人.  相似文献   
87.
通过收集广州市2011~2015年6种疾病(非意外因素、心血管疾病、脑卒中、缺血性心脏病、呼吸系统疾病以及慢性阻塞性肺疾病)逐日死亡人数、逐日NO2浓度以及同期气象资料,采用广义相加模型探讨了NO2暴露对不同疾病死亡的影响(相对危险度,RR值)和累积滞后效应,并进一步采用分层分析方法解析了冷季(11月至次年4月)和暖季(5~10月) NO2死亡风险的差异.结果表明,NO2影响急促短暂,通常持续4d.当NO2浓度升高10μg/m3,在Lag0-4d时,人群非意外死亡人数将上升2.18%(RR=1.0218;95% CI:1.0167,1.0270),在冷季与暖季分别上升2.6%(RR=1.0260;95% CI:1.0191,1.0328)与0.57%(RR=1.0057;95% CI:0.9952,1.0163),两者差异有统计学意义(P=0.002).在不同疾病中,NO2对慢性阻塞性肺疾病的影响最大.因而NO2仍然为广州地区人群健康重要的危险因素,需要加强NO2排放的控制与治理,并且加强冷季健康风险预警以保护公共健康.  相似文献   
88.
Renewable energy sources, such as wind energy, are essential tools for reducing the causes of climate change, but wind turbines can pose a collision risk for bats. To date, the population-level effects of wind-related mortality have been estimated for only 1 bat species. To estimate temporal trends in bat abundance, we considered wind turbines as opportunistic sampling tools for flying bats (analogous to fishing nets), where catch per unit effort (carcass abundance per monitored turbine) is a proxy for aerial abundance of bats, after accounting for seasonal variation in activity. We used a large, standardized data set of records of bat carcasses from 594 turbines in southern Ontario, Canada, and corrected these data to account for surveyor efficiency and scavenger removal. We used Bayesian hierarchical models to estimate temporal trends in aerial abundance of bats and to explore the effect of spatial factors, including landscape features associated with bat habitat (e.g., wetlands, croplands, and forested lands), on the number of mortalities for each species. The models showed a rapid decline in the abundance of 4 species in our study area; declines in capture of carcasses over 7 years ranged from 65% (big brown bat [Eptesicus fuscus]) to 91% (silver-haired bat [Lasionycteris noctivagans]). Estimated declines were independent of the effects of mitigation (increasing wind speed at which turbines begin to generate electricity from 3.5 to 5.5 m/s), which significantly reduced but did not eliminate bat mortality. Late-summer mortality of hoary (Lasiurus cinereus), eastern red (Lasiurus borealis), and silver-haired bats was predicted by woodlot cover, and mortality of big brown bats decreased with increasing elevation. These landscape predictors of bat mortality can inform the siting of future wind energy operations. Our most important result is the apparent decline in abundance of four common species of bat in the airspace, which requires further investigation.  相似文献   
89.
Acute toxicity testing of some industrial effluents (rubber (Rr), brewery (Br), and bottling (Bt)) on Chironomus travalensis (Diptera larvae) was determined at 96-h using a static bioassay technique. Effluent quality characterization revealed acidic pH values of 4.5 for Rr, 5.64 for Br, and 4.32 for Bt effluents. Tests were carried out in replicates between 10 and 100% effluent concentrations. Mortality rate rose progressively with increasing concentrations. Bt effluent was the most toxic with 96-h LC50 of 61.5%, closely followed by Rr effluent with 96-h LC50 of 87% and the least toxic was Br effluent with 96-h LC50 of 90%.  相似文献   
90.
The current study considered, for the first time, compensatory decisions within the theory of planned behaviour (TPB) to explain why people use mobile phones while driving. The effects of age, gender, and mobile phone mode on respondents’ answering intentions and compensatory decisions were mainly examined. A series of questions were administered to 333 drivers (ages 25-59), which included (1) demographic measures, (2) scales that measured prior mobile use activities in both driving and ordinary contexts, (3) a question to measure drivers’ perceptions of the safety of hands-free phones, and (4) TPB measures, which measured answer intention and two compensatory behavioural decisions (i.e., reminding the caller that he/she is driving, limiting the length of a conversations (including perceived its limits)), along with predictive variables. Drivers reported a moderate likelihood of answering intention and a strong tendency to engage in the two compensatory behaviours. Answering intention and compensatory decisions, perceived behavioural control, perceived risk, and usage frequency were more dependent on mobile phone mode and age group than gender. The regression models explained 64% and 67% of the variance in answering intention in the handheld and hands-free scenario separately. Attitudes, subjective norms, perceived behavioural risk and control (PBRC), and prior answering behaviour emerged as common predictors. The predictive models explained 31% and 37% of the variance for perceived limits of a conversation length in handheld and hands-free scenarios, respectively. Answering intention and PBRC consistently predicted most of the variance (handheld: 28%; hands-free: 32%) for this compensatory perception limits. The theoretical and practical implications of these results are discussed.  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