全文获取类型
收费全文 | 109篇 |
免费 | 6篇 |
国内免费 | 29篇 |
专业分类
测绘学 | 20篇 |
大气科学 | 4篇 |
地球物理 | 7篇 |
地质学 | 68篇 |
海洋学 | 6篇 |
综合类 | 9篇 |
自然地理 | 30篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 8篇 |
2018年 | 6篇 |
2017年 | 6篇 |
2016年 | 2篇 |
2015年 | 5篇 |
2014年 | 12篇 |
2013年 | 11篇 |
2012年 | 5篇 |
2011年 | 6篇 |
2010年 | 6篇 |
2009年 | 6篇 |
2008年 | 7篇 |
2007年 | 10篇 |
2006年 | 8篇 |
2005年 | 7篇 |
2004年 | 6篇 |
2003年 | 5篇 |
2002年 | 3篇 |
2000年 | 3篇 |
1999年 | 7篇 |
1998年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1991年 | 1篇 |
排序方式: 共有144条查询结果,搜索用时 15 毫秒
101.
ABSTRACTIn many arid and semi-arid countries, wastewater irrigation is becoming a common practice in agriculture. In this study, the effect of long-term (40 years) wastewater irrigation on selected physical and hydraulic properties of soil in different parts of a landscape was investigated. The performance of some infiltration models, including Philip (Ph), Kostiakov (Kos), Kostiakov-Lewis (Kos-L), Horton (Ho), Huggins and Monke (Hug-M), and linear and nonlinear Smith-Parlange (S-P(L) and S-P(NL)), was compared. This study was performed in the Urmia region, Iran, where flooding wastewater irrigation has been practised for at least 40 years. Five paired sites, each of which contained a measurement location at the wastewater-irrigated (WWI) and adjacent control area were studied. Accuracy of the infiltration models was evaluated using several statistical criteria, including root mean square error (RMSE) and Akaike information criterion (AIC). The models were classified into groups using cluster analysis based on level of similarity in their performance. The cumulative water infiltration into soils after 1 h (I1h) was calculated using the selected most accurate models and introduced so as to use only one term to compare the infiltration behaviour of soils. Based on RMSE and AIC, the performance of the Ph, Ho, Kos and Kos-L models was considerably better than that of Hug-M, S-P(L) and S-P(NL). The ranking of the models in terms of their AIC values was: Kos-L > Ho > Kos > Ph > S-P(L) > Hug-M > S-P(NL). The models were classified into two distinct groups. The similarity among Ph, Ho, Kos and Kos-L models was more than 80% and for Hug-M, S-P(L), and S-P(NL) models, it was more than 79%. However, the similarity between these two groups of models was less than 58%.
Editor M.C. Acreman; Associate editor not assigned 相似文献
102.
复合生物反应器处理城市污水的试验研究 总被引:3,自引:1,他引:3
为了提高城市污水的处理效率、降低运行成本,进行了复合生物反应器处理城市污水的试验研究,从曝气停留时间、有机负荷率、气水比等3个方面研究了试验运行的最佳条件和控制参数.试验结果表明,利用该工艺方法处理城市污水在有机负荷率高达2.44 kgCOD/kgMLSS*d的条件下,停留时间1.5~2 h,气水比(2.5~3)∶1,可使出水COD去除率达80%以上.该方法强化了混合液的物相传质速率. 相似文献
103.
随着社会经济的快速发展与城市化进程的加快,城市垃圾问题、环境问题日渐突出而自然资源日渐匮乏。借助Origin6.0 Professional做出广州市垃圾量与其影响因素的拟合曲线,分析得出广州市生活垃圾量将在较长时期内保持稳定状态。若能从减量化、资源化、无害化等角度来回收利用城市垃圾,不仅可减轻垃圾对环境的污染,节约资源,还符合可持续发展的要求。 相似文献
104.
山西城市生态环境质量评价 总被引:2,自引:0,他引:2
本文以城市生态位理论为依据,对山西省辖市以及行署所在城市的生产位、生活位、环境位三个评价体系参数进行选择和评价。 相似文献
105.
106.
青岛城市地质与可持续发展 总被引:5,自引:1,他引:5
青岛是黄海环胶州湾的一颗璀灿明珠,是一座闻名于世、风景秀丽的滨海城市,也是我国北方海岸带上重要的港口、旅游城市。海岸带是海/陆相互作用的一个特殊地带,是人类频繁活动、生产建设与经济发展最活跃的地域,同时也是一个生态环境比较脆弱的地区。了解青岛城市及其海岸带的地质环境特征与演化规律,合理规划开发、利用、保护和综合治理,以便有效地抵卸人类生存环境的不断恶化,走可持续发展的道路。从青岛城市的地质构造、矿产资源和地质环境的实际状况和自然属性出发,探讨了海洋地质在由海洋科学城向海洋产业城转变过程中的作用以及城市地质与可持续发展之路。 相似文献
107.
膜生物反应器技术与市场的发展 总被引:1,自引:0,他引:1
膜生物反应器(MBR)作为一项新型的水处理技术,具有处理效率高、出水水质好、运行管理简单等特点,在水处理领域包括自来水供给保障和污水处理回用中得到了迅速发展。文中从技术发展和市场开发两方面对MBR的现状作了扼要评论,通过历史进展的回顾,着重分析了影响MBR发展的一些关键因数,展望了MBR在市政污水和工业废水处理回用中的发展前景。 相似文献
108.
通过对青岛市目前经济发展水平和技术条件的讨论,提出了青岛市城市垃圾的处置对策。卫生填埋应为主要处置方式,少量焚烧可用于处理医院及公共场所垃圾,堆肥法由于垃圾成分、成本、销路等因素的制约,近期内不能大规模发展。 相似文献
109.
110.
Zhonggen LI Xinbin FENG Ping LI Shunlin TANG Shaofeng WANG Xuewu FU Wei ZHENG Lihai SHANG 《中国地球化学学报》2006,25(B08):238-238
Mercury (Hg) in atmosphere can indicate the air quality and the intensity of the Hg emission sources, and the potential impact of the emission source on the local, regional, and global environments. Landfill is a place where municipal solid waste is transported, dumped, spread, and buried, during these disposal processes, some Hg contained in the wastes will be released into atmosphere. This paper presents different Hg species in the atmosphere over the near surface at 5 landfills, i.e., 3 landfills in Guiyang and 2 landfills in Wuhan. Besides one operational sanitary landfill, Gaoyan, the other four landfills just present the total gaseous mercury (TGM) over 0.1 m above the ground; in the Gaoyan landfill, TGM was measured at two altitudes, 0.1 m and 2 m, and other Hg species, reactive gaseous mercury (R.GM), total particulate mercury (TPM), monomethyl mercury (MMHg) and dimethyl mercury (DMHg) were also monitored at 2 m above the ground. TGM was measured by Tekran 2537A mercury analyzer, RGM was collected by KCl coated denuders, TPM by quartz filters, MMHg absorbed by dilute HCl solution, DMHg absorbed by CarbotrapTM and analyzed by GC-CVAFS. The results showed that the TGM over the closed landfills has an obvious diurnal pattern, with maximum at daytime and minimum during nighttime, which reflects the Hg emission process over the landfill cover surface, the typical average TGM was about 10-30 ng/m^3 at 2 closed landfills, which was several times higher than the global background; at the soil covered part of the active landfills, TGM concentration range and variation are similar to those at the closed landfills; when the weather is clear, the highest TGM appeared at the working face and downwind of the wording face, TGM can reach up to 500 ng/m^3 at these places, but at raining days, there is no distinct discrepancy between TGM measured at the upwind and downwind of the working face. 相似文献