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   383篇
  免费   19篇
  国内免费   46篇
安全科学   38篇
环保管理   34篇
综合类   225篇
基础理论   102篇
环境理论   1篇
污染及防治   17篇
评价与监测   10篇
社会与环境   9篇
灾害及防治   12篇
  2023年   4篇
  2022年   6篇
  2021年   13篇
  2020年   7篇
  2019年   7篇
  2018年   6篇
  2017年   6篇
  2016年   8篇
  2015年   4篇
  2014年   8篇
  2013年   17篇
  2012年   9篇
  2011年   32篇
  2010年   12篇
  2009年   14篇
  2008年   16篇
  2007年   17篇
  2006年   28篇
  2005年   20篇
  2004年   23篇
  2003年   18篇
  2002年   16篇
  2001年   13篇
  2000年   5篇
  1999年   9篇
  1998年   6篇
  1997年   4篇
  1996年   4篇
  1995年   14篇
  1994年   15篇
  1993年   6篇
  1992年   10篇
  1991年   17篇
  1990年   3篇
  1989年   14篇
  1988年   10篇
  1987年   13篇
  1986年   2篇
  1985年   1篇
  1984年   2篇
  1983年   3篇
  1982年   2篇
  1981年   4篇
排序方式: 共有448条查询结果,搜索用时 46 毫秒
251.
● This study explored the long-term association by double robust additive models. ● Individual exposure concentrations were assessed by integrating GAM, LUR and BPNN. ● PM2.5, SO2 and NO2 are positively associated with cerebrovascular disease. ● CO could reduce the risk of cerebrovascular disease with the highest robustness. ● The elderly, women and people with normal BMI are at higher risk for air pollution. The relationship between air pollution and cerebrovascular disease has become a popular topic, yet research findings are highly heterogeneous. This study aims to investigate this association based on detailed individual health data and a precise evaluation of their exposure levels. The integrated models of generalized additive model, land use regression model and back propagation neural network were used to evaluate the exposure concentrations. And doubly robust additive model was conducted to explore the association between cerebrovascular disease and air pollution after adjusted for demographic characteristics, physical examination, disease information, geographic and socioeconomic status. A total of 25097 subjects were included in the Beijing Health Management Cohort from 2013 to 2018. With a 1 μg/m3 increase in the concentrations of PM2.5, SO2 and NO2, the incidence risk of cerebrovascular disease increased by 1.02 (95% CI: 1.008–1.034), 1.06 (95% CI: 1.034–1.095) and 1.02 (95% CI: 1.010–1.029) respectively. Whereas CO exposure could decrease the risk, with an odds ratio of 0.38 (95% CI: 0.212–0.626). In the subgroup analysis, individuals under the age of 50 with normal BMI were at higher risk caused by PM2.5, and SO2 was considered more hazardous to women. Meanwhile, the protective effect of CO on women and those with normal BMI was stronger. Successful reduction of long-term exposure to PM2.5, SO2 and NO2 would lead to substantial benefits for decrease the risk of cerebrovascular disease especially for the health of the susceptible individuals.  相似文献   
252.
新型抗毒素是一类由Penicilin sp.产生的抗病毒物质,其中喷雾使用50-400mg/L,在菜豆和黄瓜上测定对黄瓜花叶病毒(Cocumber mosaic virus,CMV)的印化效果分别为52.9%-87.5%和41.8%-61.0%;在黄瓜上于接种前后分别喷施200mg/L,对病害初侵染的作用效果分别为80.3%和65.3%,试验结果表明该类新型抗毒对黄瓜花叶病具有印化病毒粒子、抑制病害初侵染和干扰过氧化酶的活性等作用。  相似文献   
253.
猪沙门氏杆菌又称猪副伤寒,是沙门氏杆菌引起的一种传染病,多发生于2-4月龄仔猪,临床上多表现为败血症和肠炎,本病一旦发生,直接影响仔猪的成活和生长发育,给养猪业造成重大的经济损失。  相似文献   
254.
Why did the identification of ash dieback (Chalara Fraxinea) in 2012 in the UK catch the national media, public, and political zeitgeist, and lead to policy changes, in a way that no other contemporary tree pest or pathogen outbreak has? The identification of ash dieback in the UK is conceptualised as a successful ‘focusing event’, and the ways in which it was socially constructed by the media, stakeholders, and the government are analysed. National newspaper coverage contributed to the way that the disease was understood and was significant in driving the political response. Ash dieback’s focal power derived from the perceived scale and nature of its impact, the initial attribution of blame on government, the war-like response from the government, and Ash’s status as a threatened native tree. The ash dieback focusing event has increased the salience of plant health issues amongst policymakers, the public, and conservation organisations in the UK.  相似文献   
255.
Isolates of Cladobotryum dendroides from Serbian mushroom farms and Agaricus bisporus F56 were tested for sensitivity to selected fungicides in vitro. Chlorothalonil was the most toxic fungicide to C. dendroides isolates (EC50 values were below 1.68 mg L? 1). Trifloxystrobin and kresoxim-methyl were not effective in growth inhibition of C. dendroides isolates (EC50 values exceeded 300 mg L? 1). Metalaxyl-M+mancozeb was the most toxic fungicide to strain F56 of A. bisporus, and iprodione the least toxic. The fungicide selectivity indexes for both C. dendroides and A. bisporus indicated that iprodione, chlorothalonil, captan and metalaxyl-M+mancozeb had satisfactory selective fungitoxicity. Iprodione had the best selectivity to both the pathogen and the host, although inferior than prochloraz manganese and carbendazim, fungicides officially recommended for mushroom cultivation in European Union (EU) countries.  相似文献   
256.
Atmospheric CO2 concentrations are predicted to double within the next century and alter climate regimes, yet the extent that these changes will affect plant diseases remains unclear. In this study conducted over five years, we assessed how elevated CO2 and interannual climatic variability affect Cercospora leaf spot diseases of two deciduous trees. Climatic data varied considerably between the five years and altered disease expression. Disease incidence and severity for both species were greater in years with above average rainfall. In years with above average temperatures, disease incidence for Liquidambar styraciflua was decreased significantly. When significant changes did occur, disease incidence and severity always increased under elevated CO2. Chlorophyll fluorescence imaging of leaves revealed that any visible increase in disease severity induced by elevated CO2 was mitigated by higher photosynthetic efficiency in the remaining undamaged leaf tissue and in a halo surrounding lesions.  相似文献   
257.
建立了凡纳滨对虾红体病病原--副溶血弧菌的间接免疫荧光抗体检测方法.确定免疫血清和荧光抗体的最适工作浓度分别为1∶ 1000和1∶ 200;交叉反应和阻断试验表明该方法具有较高的特异性.用该方法检测了10份人工感染后发病的凡纳滨对虾和10份感染后外观健康的凡纳滨对虾,阳性检出率分别为100%和60%,表明该技术不仅能够检测已发病的凡纳滨对虾,而且能够检测带菌的凡纳滨对虾,这对于水产养殖业中疾病的早期诊断有着重要意义,而且该方法具有快速、特异、简单的优点,适合于现场应用推广.  相似文献   
258.
北京城区可吸入颗粒物分布与呼吸系统疾病相关分析   总被引:5,自引:11,他引:5  
可吸入颗粒物(PM10)已成为北京市首要空气污染物,严重影响城市环境质量及居民健康.本研究采集了北京市2008~2009年非采暖期与采暖期两个不同时期不同粒径(0.3、0.5、3.0和5.0μm)的大气颗粒物浓度,利用空间分析方法研究其分布规律;同时收集同期患呼吸系统疾病的病人数据,对其进行统计分析;再在回归分析的基础上,运用灰色关联模型探讨可吸入颗粒物与呼吸系统疾病的相关性.结果表明,细颗粒的空间分布情况相异,而粗颗粒物分布规律大致相同.呼吸系统疾病与可吸入颗粒物浓度有一定的关联,采暖期是呼吸系统疾病的高发期,可吸入颗粒物在采暖期对呼吸系统疾病的发病率影响相对较高.无论在采暖期还是非采暖期,细颗粒物的浓度均高于粗颗粒物,且细颗粒物对呼吸系统疾病的影响较大.  相似文献   
259.
松花江甲基汞污染危害的环境流行病学研究   总被引:5,自引:0,他引:5       下载免费PDF全文
调查了从第二松花江饮马河口至第一松花江同江全长1271km沿江重点人群受甲基汞污染危害的情况。查出慢性中毒2人,观察对象18人,甲基汞吸收120人。受害者症状轻微,基本稳定,无明显自觉症状。发汞和甲基汞较汞污染治理前有显著下降,说明治理取得了显著的健康效益。但少数人体内仍有过量的汞和甲基汞蓄积,为防止敏感者受害,每周食松花江鱼量不应超过2kg。文中还对诊断、受害者的年龄、性别和发病江段作了讨论。  相似文献   
260.
上海地区果树根癌病发生与土壤环境的关系   总被引:1,自引:0,他引:1  
果树根癌病(致病菌为根癌土壤杆菌Agrobacterium tumefaciens)目前在上海地区大面积发生,严重危害桃(Amygdalus persicaL.)、梨(Pyrus bretschneideri Rehd.)、苹果(Malus pumila Mill.)等果树的生长。本文采用化学分析及微生物培养等方法,研究了上海地区桃树和梨树根癌病的发生与土壤因子(土壤含水量、pH值、有机质含量),土壤细菌以及与不同果树品种之间的关系。结果表明:土壤含水量、pH值、有机质含量、土壤中微生物的多样性和微生物总体数目与病害的发生没有显著的相关性,但是土壤中存在的个别菌种对病害的发生有显著的影响,初步分析显示Agrobacterium sp.和Bacillus sp.对根癌病的发生具有抑制作用,而Psuedomonas sp.对根癌病的发生可能具有一定的促进作用。同时不同果树品种的病害发生率之间有显著性的差异。  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