全文获取类型
收费全文 | 290篇 |
免费 | 32篇 |
国内免费 | 65篇 |
专业分类
安全科学 | 30篇 |
废物处理 | 8篇 |
环保管理 | 22篇 |
综合类 | 190篇 |
基础理论 | 62篇 |
环境理论 | 1篇 |
污染及防治 | 30篇 |
评价与监测 | 14篇 |
社会与环境 | 22篇 |
灾害及防治 | 8篇 |
出版年
2023年 | 8篇 |
2022年 | 15篇 |
2021年 | 8篇 |
2020年 | 26篇 |
2019年 | 11篇 |
2018年 | 19篇 |
2017年 | 13篇 |
2016年 | 12篇 |
2015年 | 18篇 |
2014年 | 17篇 |
2013年 | 23篇 |
2012年 | 29篇 |
2011年 | 26篇 |
2010年 | 19篇 |
2009年 | 21篇 |
2008年 | 21篇 |
2007年 | 24篇 |
2006年 | 17篇 |
2005年 | 12篇 |
2004年 | 15篇 |
2003年 | 6篇 |
2002年 | 8篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1998年 | 5篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1927年 | 3篇 |
排序方式: 共有387条查询结果,搜索用时 15 毫秒
31.
32.
The pH on the frustule of individual cells of the marine centric diatoms Coscinodiscus granii and Coscinodiscus wailesii (Bacillariophyceae) was measured with pH microsensors in culture media with increasing pH values of 8.04, 8.14, and 8.22,
respectively. In 85–96% of the C.
granii cells the pH on the frustule was up to 0.4 units higher than that of the medium, reaching a maximum pH 8.95. Only in 2–3%
the surface pH exceeded that of the medium by up to 0.7 pH units. These results strongly suggest that diatoms in batch cultures
differ, at least temporarily, in their individual photosynthetic activities. Infection experiments with the parasitoid nanoflagellate
Pirsonia diadema (Stramenopile) showed that flagellates failed to infect when the culture pH was 8.8 and above. pH measurements on freshly
infected C. granii showed that the prevalence of infection was higher in tendency on diatoms with low surface pH. Application of these results
to parasitoid-diatom interactions in natural waters suggests that within phytoplankton populations a strong photosynthetic
activity might prevent diatom cells temporarily from infection by pH-sensitive parasitoids. 相似文献
33.
高校图书馆消防安全疏散数值分析 总被引:2,自引:1,他引:1
以国内某高校图书馆为实例,利用FDS和Pathfinder对该图书馆进行火灾及人员疏散全尺寸模拟。研究图书馆发生火灾时烟气扩散、温度分布及能见度对人员逃生的影响。主要方法为通过火灾模拟软件FDS模拟分析发生火灾时的可用安全疏散时间(ASET),并使用疏散模拟软件PathFinder计算所需安全疏散时间(RSET),进而判断图书馆目前管理状况是否满足火灾时的人员安全疏散需要。结论表明:该图书馆目前管理状况不能满足火灾条件下人员逃生的需要,而影响人员安全疏散的主要因素为烟气的扩散。在研究结果的基础上提出改进建议,为图书馆日后的管理及灭火救援提供理论依据。 相似文献
34.
对从土壤中分离出的321株菌株进行了筛选,得到1株高产胞外黑色素的菌株,比较了其在不同培养基上产黑色素的能力.初步确定该菌株为链霉菌属.该菌黑色素产量高,约为0.70g/L,在产黑色素的微生物中,链霉菌可以作为一类新的菌种资源.图2表1参15 相似文献
35.
36.
浙江天台山茶树光合日变化及光响应 总被引:18,自引:1,他引:18
自然条件下使用LCA-4型便携式光合测定系统研究了栽培天天台山主峰华顶山的茶树连体叶片的光合日变化及光响应。结果表明:在初夏晴天,上年越冬叶片(下称二年生叶)的光合速率,表观量子效率,羧化效率和饱和光强比展叶红16d的一年生叶高,CO2补偿点和光补偿点比一年生叶低,两者的净光合速率日进程曲线均为“双峰”型,午间胞间CO2浓度上升表明,此时净光合速率下降主要受非气孔限制因素的影响。一年生叶蒸腾速率高于二年生叶,它们日进程曲线为单峰河,午间最高,而气孔阻力进间最低。不同时段作光响应和CO2响应试验表明,上午茶树的表观量子效率,饱和光强和羧化效率较高,光补偿点和CO2补偿点较低。图3表4参26 相似文献
37.
Statistical modeling of seasonal and environmental influences on the population dynamics of an estuarine fish community 总被引:1,自引:0,他引:1
A statistical modeling study was performed on the population fluctuations of the 15 commonest fish species frequenting the tidal Scheldt estuary in Belgium. These included marine juvenile and seasonal visitors, estuarine residents and diadromous fish species that were recorded on the filter screens of a power plant cooling-water intake between September 1991 and April 2001. The species population abundance was regressed against a candidate set of 6 environmental variables and 13 instrumental variables, accounting for seasonality and long-term trends present in the data. Population abundances of the different species were, in general, best described by seasonal variables. Seasonal components contributed, on average, up to 63.8% of the variance explained by the models. Ten species were found to show a slightly negative, though significant, trend over the period of the survey. Most models also included at least one environmental variable, and 25.4% of the explained variance could be attributed to environmental fluctuations. Of all physico-chemical variables, dissolved oxygen was the most important predictor of fish abundance, suggesting that the estuary suffered from poor water quality during the survey. Temperature, salinity, freshwater flow, suspended solids and chlorophyll a concentrations were minor determinants of fish abundance.Communicated by O. Kinne, Oldendorf/Luhe 相似文献
38.
Melina Campero Stefanie Slos Frans Ollevier Robby Stoks 《Ecological applications》2007,17(7):2111-2122
Despite their relevance for risk assessment, the interactive effects of pesticide and predation cues are poorly understood because the underlying behavioral and physiological mechanisms are largely unknown. To explore these mechanisms, we reared larvae of the damselfly Coenagrion puella at three different predation risk levels and a range of environmentally realistic concentrations of three pesticides used worldwide (atrazine, carbaryl, and endosulfan). We compared key development responses (growth rate, developmental time, and final size) against food ingestion, assimilation, and conversion efficiency, and acetylcholinesterase (AChE) activity. Predation risk impaired all endpoints, including AChE activity, while the effects of pesticide stress were smaller for atrazine and endosulfan and absent for carbaryl. The effects of both stressors and their interaction on life history were mostly indirect through resource acquisition and energy allocation. Compensatory physiological mechanisms to pesticide stress (atrazine and endosulfan) were present in larvae reared in the absence of predation stress but were offset under predation stress. As a result, smaller size (atrazine and endosulfan) and lower growth rate (endosulfan) from pesticide stress were only found in the highest predation risk treatment. Our results provide insight as to the conditions under which interactions between stressors are likely to occur: damselfly populations at high density and living in fish ponds will be more affected by pesticides than populations at low densities in fishless ponds. By identifying variables that may shape the interaction between predation stress and other stressors such as pesticides, our mechanistic approach may help to bridge the gap between laboratory and field studies. 相似文献
39.
40.
以中国福建省福州市晋安区解放溪流域高密度居民住宅区为例,针对不同降雨重现期、降雨历时和雨峰系数的降雨情景,利用PCSWMM模型模拟该地区的雨洪情况,并运用模型的低影响开发(LID)模块,研究7种不同LID用地布局情景对研究区内涝节点的雨洪控制效果.情景模拟结果表明:在不同降雨情景下,各LID用地布局情景会使节点的洪峰流量减小、积水时间减少、积水深度变小;植被浅沟措施和植被浅沟&绿色屋顶组合措施会使节点SS峰值浓度高于现状用地,其余布设情景下,SS峰值浓度均减小.LID措施对节点流量和水质的控制效果在低降雨重现期和长降雨历时的降雨情景下较为有效.在单个LID布设情景中,渗透铺装措施控制最佳,而组合LID布设情景中,渗透铺装&植被浅沟&绿色屋顶是最佳的组合控制措施.研究结果可为南方城市居民区实施海绵城市建设提供技术支持,并为地方制定相关规范和标准提供参考和借鉴. 相似文献