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   212篇
  免费   22篇
  国内免费   61篇
安全科学   55篇
废物处理   3篇
环保管理   35篇
综合类   116篇
基础理论   37篇
污染及防治   25篇
评价与监测   2篇
社会与环境   12篇
灾害及防治   10篇
  2023年   1篇
  2022年   9篇
  2021年   17篇
  2020年   9篇
  2019年   6篇
  2018年   6篇
  2017年   15篇
  2016年   13篇
  2015年   8篇
  2014年   11篇
  2013年   27篇
  2012年   27篇
  2011年   14篇
  2010年   17篇
  2009年   10篇
  2008年   7篇
  2007年   22篇
  2006年   8篇
  2005年   10篇
  2004年   6篇
  2003年   3篇
  2002年   9篇
  2001年   9篇
  2000年   6篇
  1999年   6篇
  1998年   6篇
  1997年   2篇
  1996年   5篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1992年   1篇
  1991年   1篇
  1990年   1篇
排序方式: 共有295条查询结果,搜索用时 93 毫秒
241.
In consideration of the need to maintain planting-breeding balance, this article examines the capacity of the soil in Putian City, Fujian Province to absorb livestock and poultry excreta, and computes the environmental carrying capacity for livestock and poultry farming (ECCLPF) in each district of the city in terms of the fertility characteristics of the soil in the city, as well as its mix of crops cultivated and farming methods. On the basis of the computations, this work proceeds to classify the alarm grades of the city’s environmental carrying capacity for livestock and poultry framing, and assess the environmental impact of the livestock and poultry farming industry. The results of our study indicate that, the city’s ECCLPF ranges from 8.27 to 23.23 heads per ha when computed on the basis of nitrogen, and from 5.79 to 24.53 heads per ha when computed on the basis of phosphorus. A comparison between our research findings and the existing farming scale in Putian reveals that, in certain parts of the city, ECCLPF is overburdened to varying degrees. Specifically, Chengxiang District is severely overburdened, Hanjiang District and Meizhou Island have a level of overburdening between virtual overburdening and significant overburdening, Licheng District is virtually overburdened, and Xiuyu, Xianyou, and Bei’an Districts have not exceeded their environmental carrying capacity and therefore have varying levels of potential for growth.  相似文献   
242.
两种缓蚀剂对10CrSiNiCu钢的缓蚀效果研究   总被引:4,自引:0,他引:4       下载免费PDF全文
采用极化曲线等电化学研究方法研究单独添加不同类型缓蚀剂葡萄糖酸钠、钼酸钠以及二者复配后在3%(质量分数)NaCl溶液中对10CrSiNiCu低合金钢的缓蚀效果。研究结果表明,葡萄糖酸钠为阴极型缓蚀剂,而钼酸钠为阳极型缓蚀剂,而二者复配后则缓蚀效果降低,产生拮抗作用。  相似文献   
243.
从网络营销4P组合因素——产品(product)、价格(price)、渠道(place)及促销(promotion)的具体特点出发,比较了网络营销4P组合策略与传统营销组合策略的不同,并对网络营销4P组合策略进行了具体分析。  相似文献   
244.
火电厂清洁生产与环境管理一体化实施初探   总被引:1,自引:0,他引:1  
火电厂清洁生产的推行,需运用系统的观点,运用清洁生产审核这一重要的技术手段,提出方案并实施.火电厂清洁生产的持续性特点,需要建立火电厂环境管理体系来支持.文章从技术手段和管理手段的角度,提出火电厂清洁生产与环境管理体系一体化实施的观点.  相似文献   
245.
光催化氧化与生物氧化组合技术对染料化合物降解研究   总被引:31,自引:1,他引:31  
将多相光催化氧化法与生物氧化法相结合,探讨两种组合技术对染料化合物的降解。实验选用100ppm的甲基橙和典型实验溶液,适当配以一定浓度范围的生活污水,以保证生物菌种的生存条件。实验结果证明先生物氧化、后光催化氧化是一种比较好的组合方式,24h生物氧化,溶液COD去除达69.68%,色度去除达22.39%,随后光催化氧化1h,COD去除达84.65%,色度去除达91.31%。由此说明,这种组合方式可以体现出两种反应的互补性,尤其对生化处理后的残留色度有明显的改善。  相似文献   
246.
介绍了几种不同组合的防护装饰性镀层经16年大气曝露试验后的情况。结果表明:具有约40μm厚度的多层镍 微孔铬或微裂纹铬组合镀层可以有效地保护钢铁基体在亚热带气候条件下免遭腐蚀:而厚度达60μm的普通铜 镍 铬、镍 铬组合镀层对钢铁基体不能提供可靠的腐蚀保护。  相似文献   
247.
刘颖  覃仁辉 《地球与环境》2005,33(Z1):459-462
结合现有的基坑土钉支护设计规范,通过合理分析计算,介绍了贵阳某综合楼基坑支护中预应力锚索锚杆联合支护方案。实践证明,在岩体破碎和地下水资源较丰富的条件下,该类型支护方案能取得较好的效果。  相似文献   
248.
The influence of antimicrobial agents approved as veterinary drugs in Japan on the growth of green algae, Selenastrum capricornutum and Chlorella vulgaris, was studied in accordance with the OECD guidelines for testing chemicals. Among the agents tested, growth inhibitory activity was very varied, i.e. erythromycin showed the strongest activity (EC50, 50% effective concentration, =0.037 mg/l), sulfa drugs had activity to some extent (EC50s of sulfamethoxazole, sulfadiazine, and sulfadimethoxine were 1.5, 2.2, and 2.3 mg/l, respectively), but ampicillin and cefazolin did not inhibit growth (EC50s > 1000 mg/l). We also investigated synergistic effect of combining sulfa drugs with trimethoprim or pyrimethamine, which are commonly used as a combined drug. By adding trimethoprim, the growth inhibitory activity of sulfamethoxazole and sulfadiazine was significantly enhanced. Growth inhibition by sulfa drugs was reduced by the addition of folic acid, indicating that they inhibit folate synthesis in green algae.  相似文献   
249.
通过田间试验研究了不同肥料组合处理对生菜硝酸盐和重金属累积的影响。结果表明,加施复合剂的3个处理对生菜硝酸盐的降低效果较好,其中施用双氰胺的组合处理在3个生长时期的降低幅度分别为24%、20.1%、65.4%,降低作用均为最大;施用植物材料处理的生菜Hg质量分数最大,高磷组合处理生菜的Cr、Cd、As和Pb质量分数最大,过磷酸钙增加了Cr、Cd、As和Pb的有效性,氯化钾对重金属影响不明显;仅加施微量元素和施用双氰胺组合处理的卫生品质最好,高磷组合处理卫生品质最差。  相似文献   
250.
Objective: It is well known that alcohol and drugs influence driving behavior by affecting the central nervous system, awareness, vision, and perception/reaction times, but the resulting effect on driver injuries in car crashes is not fully understood. The purpose of this study was to identify factors affecting the injury severities of unimpaired, alcohol-impaired, and drug-impaired drivers.

Method: The current article applies a random parameters logit model to study the differences in injury severities among unimpaired, alcohol-impaired, and drug-impaired drivers. Using data from single-vehicle crashes in Cook County, Illinois, over a 9-year period from January 1, 2004, to December 31, 2012, separate models for unimpaired, alcohol-impaired, and drug-impaired drivers were estimated. A wide range of variables potentially affecting driver injury severity was considered, including roadway and environmental conditions, driver attributes, time and location of the crash, and crash-specific factors.

Results: The estimation results show significant differences in the determinants of driver injury severities across groups of unimpaired, alcohol-impaired, and drug-impaired drivers. The findings also show that unimpaired drivers are understandably more responsive to variations in lighting, adverse weather, and road conditions, but these drivers also tend to have much more heterogeneity in their behavioral responses to these conditions, relative to impaired drivers. In addition, age and gender were found to be important determinants of injury severity, but the effects varied significantly across all drivers, particularly among alcohol-impaired drivers.

Conclusions: The model estimation results show that statistically significant differences exist in driver injury severities among the unimpaired, alcohol-impaired, and drug-impaired driver groups considered. Specifically, we find that unimpaired drivers tend to have more heterogeneity in their injury outcomes in the presence potentially adverse weather and road surface conditions. This makes sense because one would expect unimpaired drivers to apply their full knowledge/judgment range to deal with these conditions, and the variability of this range across the driver population (with different driving experiences, etc.) should be great. In contrast, we find, for the most part, that alcohol-impaired and drug-impaired drivers have far less heterogeneity in the factors that affect injury severity, suggesting an equalizing effect resulting from the decision-impairing substance.  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