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1.
生态浮床对河口水质的净化效果研究   总被引:12,自引:1,他引:11  
通过分析浮床建成前后、浮床撤除前后以及浮床边和开阔水道之间水质的差异,考察了浮床对河口水质的净化效果,并对净化机理进行了分析.结果表明,生态浮床具有很强的净化能力,经过浮床段后TN、TP和NH 4-N浓度均得到明显降低;浮床边的水质较好,浮床对TP、TN、NH4 -N的净去除率分别为10.4%、8.1%、18.1%;由于氮循环过程的复杂性,经过浮床段后NO-3-N和NO-2-N浓度反而显著升高;工程段水质的改善是湖水稀释、河流自净和浮床净化等综合作用的结果;撤除浮床后,对水体的净化效果大大降低,对TP、TN、NH4 -N的去除率仅分别为18.2%、9.2%、27.8%.  相似文献
2.
To assess the fate of the large amounts of nitrogen (N) brought into the agricultural environment by human activities in the Changjiang River basin, we used [China's county level agricultural database of 1980 and 1990. National Resources and Environmental Data Center, China] and published conversion data to set up a complete N budget for the Changjiang River basin. Sources considered include imported N such as atmospheric deposition, inorganic fertilizer, biological fixation and manure. Dominant losses considered include crop harvests, denitrification of soil nitrate and NH3 volatilization, and the budget was estimated from the difference between all inputs and all outputs. Therefore, the geographic distribution of excess N, considered as lost, by N storage in farmland and N transported to water bodies in Changjiang River basin was analyzed. In the Changjiang River basin, the anthropogenic reactive N has far exceeded the terrestrial bio-fixed N in nature, and human activities have significantly altered the N cycle in this region. The total inputs of N in 1980 and 1990 were 8.0 and 12.9 Tg N, respectively. The total N outputs are 4.41 Tg N in 1980 and 6.85 Tg N in 1990. Thus, the excess N that was stored in farmland was 1.51 Tg N at 1980 and 2.67 Tg N at 1990, respectively, and losses through transportation to water bodies in 1980 was 2.08 and 3.38 Tg N in 1990, respectively. Our research shows that from 1980 to 1990, cultivated land increased 5.9%, grain production increased 30% and N fertilizer-use increased 106%, but the N fertilizer-use efficiency decreased 36%, and the variations in the distribution of N fertilizer-use efficiency, N budgets and N transport to water bodies tended to coincide with each other geographically.  相似文献
3.
天津津塔工程超大深基坑施工技术   总被引:8,自引:6,他引:2  
天津津塔工程建筑高度336.9m,是目前华北地区最高建筑.其基坑面积19 764m2,基坑开挖深度达-32.1m.工程整体采用顺作法.周边围护结构采用两墙合一的地下连续墙和双圆环钢筋混凝土内支撑体系,支撑立柱采用钻孔灌注桩内插角钢格构柱形式.止水帷幕和基底加固采用高压旋喷桩,解决了基坑抗渗和土体加固问题;大小环岛式土方开挖技术配合旋转坡道,解决了土层软且基坑开挖深度深问题;支撑结构"闷拆"保证了主体结构正常向上施工;信息化手段可保证及时调整施工方案,保证超大、超深基坑安全稳定施工.  相似文献
4.
Zhang Y  Guo CS  Xu J  Tian YZ  Shi GL  Feng YC 《Water research》2012,46(9):3065-3073
In this work, three receptor models (Principal Component Analysis-Multiple Linear Regression (PCA-MLR) model, Unmix model and Positive Matrix Factorization (PMF) model) were employed to investigate potential source apportionment of PAHs in sediments from Taihu Lake, China. A total of 15 priority PAHs in 29 sediments from Taihu Lake were measured, with ∑PAHs (sum of 15 PAHs) concentrations ranging from 209 to 1003 ng g−1 dw. Source apportionment results derived from three different models were similar, indicating that the highest contribution to ∑PAHs was from vehicular emission (53.6-54.3%), followed by coal combustion (23.8-28.8%) and wood combustion (11.9-16.0%). The contribution of mixed wood and coal combustion source identified by PCA-MLR was 41.3%. For the first time the risk assessment for each identified source category was quantitatively calculated by combining the BaP equivalents (BaPE) values with estimated source contributions. The results showed that vehicular emission posed the highest toxic risk, with BaPE values of 26.9-31.5 ng g−1 dw, and the BaPE values for coal combustion and wood combustion were 6.56-15.6 ng g−1 dw and 2.94-6.11 ng g−1 dw, respectively. The distributions of contribution and BaPE for each identified source category were studied as well, and showed similar trends among the sampling sites, for each source category.  相似文献
5.
地下水脆弱性评价研究综述   总被引:5,自引:0,他引:5  
地下水脆弱性评价是地下水资源保护的重要依据。本文对地下水脆弱性评价的概念、脆弱性评价方法进行了论述,提出了目前地下水脆弱性研究中存在的问题,并对今后的发展方向进行了展望。  相似文献
6.
污泥减量化水处理技术的研究进展   总被引:5,自引:0,他引:5  
针对污泥处理处置过程中的环境问题和经济问题,从基于微生物隐性生长、代谢解偶联、微型动物捕食和维持代谢等方面阐述了污泥减量化水处理技术的的研究进展,介绍了相关工艺的原理和特点,并指出了其研究的发展方向和应用前景.  相似文献
7.
Twenty-five kinds of seven categories of foods were sampled in December 2008 and the concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) were determined. The highest level of total PAHs was detected in pork (195.30 ng/g) whereas the lowest concentration was found in milk (8.73 ng/g). The median values of B[a]P equivalent (B[a]Peq) daily exposure doses for children, adolescents, adults and seniors of male were estimated to be 392.42, 511.01, 571.56 and 532.56 ng/d, respectively, whereas those for the above population groups of female were found to be 355.16, 440.51, 487.64 and 444.85 ng/d, respectively. The incremental lifetime cancer risk (ILCR) values at the 22.1th, 26.1th, 12.7th, 24.9th, 22.7th, 27.0th, 12.9th, and 25.5th percentiles for male children, male adolescents, male adults, male seniors, female children, female adolescents, female adults and female seniors, respectively, were larger than 10− 6, indicating high potential carcinogenic risk, and were larger than 10− 4 at the 74.5th, 78.7th, 60.6th, 77.4th, 75.3th, 79.5th, 60.8th and 77.9th percentiles for the above groups, respectively, which implied significant cancer risk. Sensitivity analysis found that the two variables of oral cancer slope factor of benzo(a) pyrene (SF) and the daily dietary PAH exposure level (ED) had the greater impact than that of body weight (BW) on the ILCR.  相似文献
8.
日本净化槽技术管理体系经验及启示   总被引:5,自引:1,他引:4  
对于净化槽,日本已经形成了一套比较完善的技术管理体系,并支撑和规范着净化槽技术的推广和使用.介绍了净化槽技术在日本的发展历史及现状,并从政策法规、技术标准、认证体系、性能评价制度、技术服务体系等方面介绍了净化槽技术管理体系在日本的成功运行经验.完善的技术管理体系是净化槽技术能够在日本推广并健康运行的根本保障.中国在环境保护技术管理体系的建设过程中应积极借鉴国外的成功经验,提高体系建设的科学性、实效性.  相似文献
9.
基尼系数法在水污染物总量分配中的应用   总被引:4,自引:0,他引:4  
将应用在经济领域的基尼系数引入环境领域,应用环境基尼系数这一新概念建立了一套新的流域内各区域间水污染物总量分配方法。通过研究确定了该方法中的控制指标、运算规则及具体的计算方法,并将该方法用于海河流域天津市COD的总量分配中。结果表明,应用该方法能够根据各区域的实际情况较公平地将排污指标进行分配,效果良好。  相似文献
10.
腈纶生产废水的处理特点及研究进展   总被引:4,自引:0,他引:4  
由于腈纶生产废水成分复杂,存在着生物抑制性成分,难以生物降解,目前还没有解决该问题的关键技术。基于我国腈纶生产废水处理工艺和方法的复杂化,且处理效果很不理想的现状,比较了腈纶两种生产工艺的废水水质特征,总结了近年来腈纶生产废水的主要处理研究现状及发展方向,并结合两年来腈纶生产废水处理研究的体会,提出了一些看法和建议,可为同类研究提供一定的参考。  相似文献
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