检索结果-南通市图书馆

Effects of temperature and age on physico-mechanical properties of cemented gravel sand backfills

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2020年第10期27卷 2999-3012页

作者： JIANG Fei-fei ZHOU Hui SHENG Jia kou yong-yuan LI Xiang-dong State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China University of Chinese Academy of Sciences Beijing 100049China National Engineering Research Center for Metal Mining Changsha Institute of Mining Research Co.Ltd.Changsha 410012China School of Resource&Environment and Safety Engineering Hunan University of Science and TechnologyXiangtan 411201China Jinchuan Group Co. Ltd.Jinchang 737104China

Cemented backfill used in deep mines would inevitably be exposed to the ambient temperature of 20−60℃in the next few *** this paper,two types of cemented gravel sand backfills,cemented rod-mill sand backfill(CRB)and cemented gobi sand backfill(CGB),were prepared and cured at various temperatures(20,40,60℃)and ages(3,7,28 d),and the effects of temperature and age on the physico-mechanical properties of CRB and CGB were investigated based on laboratory *** show that:1)the effects of temperature and age on the physico-mechanical properties of backfills mainly depend on the amount of hydration products and the refinement of cementation *** temperature has a more significant effect on thermal expansibility and ultrasonic performance at early ages.2)The facilitating effect of temperature and age on the compressive strength of CGB is higher than that on *** the increase of temperature,the compressive failure modes changed from X-conjugate shear failure to tensile failure,and the integrity of specimens was significantly improved.3)Similarly,the shear performance of CGB is generally better than that of *** temperature has a weaker effect on shear strength than age,but the shear deformation and shear plane morphology are closely related to temperature.

关键词： cemented backfill gravel sand temperature physico-mechanical properties deformation characteristics

青藏高原东部高山森林的地上固碳速率:未来森林管理方案的影响

在线全文

学校读者我要写书评

暂无评论

Journal of Plant Ecology 2023年第3期16卷 177-190页

作者： Yang Lin Jiang-Tao Xiao yong-Ping kou Jia-Xing Zu Xin-Ran Yu Yuan-Yuan Li Ministry of Education Key Laboratory of Land Resources Evaluation and Monitoring in Southwest China Sichuan Normal UniversityChengdu 610066China School of Geography and Resource Science Sichuan Normal UniversityChengdu 610101China CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization&Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province Chengdu Institute of BiologyChinese Academy of SciencesChengdu 610041China Ministry of Education Key Laboratory of Environment Change and Resources Use in Beibu Gulf Nanning Normal UniversityNanning 530001China

青藏高原东部的高山森林是长江上游的重要生态屏障。然而,由于近几十年来持续的高强度采伐,大量的人工种植,以及完全的禁伐等措施,导致树木种类与年龄结构变得相对单一,生物多样性和生态功能都有所下降。为设计有效的森林管理方案,以优... 详细信息

青藏高原东部的高山森林是长江上游的重要生态屏障。然而,由于近几十年来持续的高强度采伐,大量的人工种植,以及完全的禁伐等措施,导致树木种类与年龄结构变得相对单一,生物多样性和生态功能都有所下降。为设计有效的森林管理方案,以优化森林结构,提高森林碳汇能力,本研究以四川茂县为研究地点,利用LANDIS-II模型对6种不同强度的森林管理方案(采伐、种植)进行测试,模拟和比较了这些方案与当前管理方案在未来100年间森林地上固碳速率的差异。研究结果表明:(i)与目前的管理方案相比,不同强度的采伐和种植明显改变了森林地上固碳速率;(ii)不同群落对管理方案的反应不同,不同的管理方案对寒温带针叶林和温带针叶林的地上固碳速率有显著的影响(P<0.05),但对阔叶林影响较小;(iii)应综合物种、群落和景观3个层面全面考虑森林管理方案。这些结果说明,在研究地点实施较长的采伐和种植间隔(20年)可以最大限度地提高森林的地上固碳速率。该研究为评估森林管理方案在恢复森林生态和增加碳汇功能的能力,以及为在青藏高原东部地区选择有效的森林管理方案提供了重要参考。

关键词：地上固碳速率物种与群落森林管理生态过程森林景观模型高山森林青藏高原

用科学发展观破解郑州大学发展进程中的“三大课题”

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

郑州大学学报（哲学社会科学版） 2006年第3期39卷 5-8页

作者：郑永扣郑州大学马克思主义哲学研究中心河南郑州450001

在对外开放和社会主义市场经济条件下,如何办好社会主义新型大学;在经济相对落后的内陆地区和资源比较匮乏的条件下,如何创建全国一流大学;在三校合并、多校区运行且又缺乏现成经验的复杂局面下,如何领导和管理好巨型大学。这三大课题... 详细信息

在对外开放和社会主义市场经济条件下,如何办好社会主义新型大学;在经济相对落后的内陆地区和资源比较匮乏的条件下,如何创建全国一流大学;在三校合并、多校区运行且又缺乏现成经验的复杂局面下,如何领导和管理好巨型大学。这三大课题与学校的整体发展和未来走向密切相关,关系到学校大政方针的制定,牵涉到学校教学、科研、管理的方方面面。在深入调研、科学论证的基础上,创造性地做好“三大课题”的研究工作,破解学校建设和发展中的重大矛盾和问题,这不仅对郑州大学创建全国一流大学具有重大现实意义和深远的战略意义,而且对我国高等教育的发展也将会有积极的借鉴意义。

关键词：科学发展观高等教育郑州大学

在线全文

学校读者我要写书评

暂无评论

基于元胞自动机的民航运输产业竞争演化模拟

系统工程理论与实践 2011年第9期31卷 1680-1686页

作者：寇勇刚吴桐水柳青南京航空航天大学民航学院南京210016 中国民航大学经管学院天津300300

为研究民航运输产业的竞争演化,考虑航空公司的资源竞争力、职能竞争力、核心竞争力及动态核心能力四层次竞争力等因素,建立了元胞自动机模型.以中美两国民航运输产业的竞争演化为例,对主导元胞(航空公司)和支持元胞(机场)的协同发展及... 详细信息

为研究民航运输产业的竞争演化,考虑航空公司的资源竞争力、职能竞争力、核心竞争力及动态核心能力四层次竞争力等因素,建立了元胞自动机模型.以中美两国民航运输产业的竞争演化为例,对主导元胞(航空公司)和支持元胞(机场)的协同发展及其盈利状况进行了模拟研究.研究结果表明,美国民航业放松航空管制后因航空公司动态核心能力不强,行业整体盈利状况不佳;我国民航业半放松管制后,盈利状况也不容乐观.然而,提高航空公司的动态核心能力既可以避免美国民航业发展中经营惨淡的局面,同时又能促进我国民航业的快速发展.

关键词：元胞自动机民航运输产业航空公司核心竞争力动态核心能力演化

Biomimetic Phosphohydrolase Nanozyme Based on Defect-Engineered Metal-Organic Framework

在线全文

学校读者我要写书评

暂无评论

CCS Chemistry 2024年第7期6卷 1821-1835页

作者： Xiaoxue kou Yuhong Lin yong Shen Linjing Tong Rui Gao Suya Liu Siming Huang Fang Zhu Guosheng Chen Gangfeng Ouyang MOE Key Laboratory of Bioinorganic and Synthetic Chemistry School of ChemistrySun Yat-sen UniversityGuangzhou 510006 Shanghai NanoPort Thermo Fisher ScientificPudong DistrictShanghai 200120 Guangzhou Municipal and Guangdong Provincial Key Laboratory of Molecular Target and Clinical Pharmacology The NMPA and State Key Laboratory of Respiratory DiseaseSchool of Pharmaceutical Sciences and The Fifth Affiliated HospitalGuangzhou Medical UniversityGuangzhou 511436

Phosphodiester bonds are the backbone linkages of all the nucleic acids which store and transfer biological *** hydrolysis of phosphodiester bonds is of great importance to the replication,recombination,and damage repair of DNA as well as the maturation and processing of ***,the spontaneous scission of individual phosphodiester linkages is kinetically challenging under physiological conditions,with an estimated half-life of 30 million ***,we discover a defect-engineered Zr-metal-organic framework(Zr-MOF)nanozyme containing cluster-missing reo defects,named UiO-66 REO,that possesses intrinsic phosphodiesterase-like activity that allows for the cleavage of the phosphodiester bond in physiological condition(pH=7.4 and 37℃),outperforming the activityrecording *** atomic-level structure of the UiO-66 REO nanozyme has been directly identified by the synchrotron radiation absorption spectrum and integrated differential phase contrast-scanning transmission electron *** find that both the defective boundary regions and unusual Zr6-clusters formed in the reo phase of the UiO-66 REO nanozyme contribute to the improvement in efficiency of phosphodiesterase-like hydrolysis,which realizes the cleavage of DNA in mild *** work offers a new insight into biomimetic enzymology using crystal and defect engineering and opens up new possibilities for the development of low-cost,structurally stable and sustainable phosphodiesterase nanozymes for different biological applications.

关键词： nanozyme metal-organic framework biomimetic catalysis hydrolase-like activity defective engineering

Effect of polypropylene fiber and coarse aggregate on the ductility and fluidity of cemented tailings backfill

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Central South University 2022年第2期29卷 515-527页

作者： YAN Rong-fu LIU Jia-ming YIN Sheng-hua ZOU Long kou yong-yuan ZHANG Peng-qiang Key Laboratory of Ministry of Education of Efficient Mining and Safety of Metal Mines University of Science and Technology BeijingBeijing 100083China School of Earth Sciences East China University of TechnologyNanchang 330013China School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China National Key Laboratory of Nickel and Cobalt Resources Comprehensive Utilization Gansu Jinchuan Group Co.Ltd.Jinchang 737100China Jinchuan Nickel Cobalt Research and Design Institute Co. Ltd.Jinchang 737100China

Adding polypropylene(PP)fibers and coarse aggregates has become a popular way to enhance the strength and stability of the cemented tailings backfilling(CTB)*** is essential to explore the influence of tailings-aggregate ratio and fiber content on the mechanical properties of CTB *** comprehensive tests of the unconfined compressive strength(UCS),slump and microstructure were designed,and the regression models were established to characterize the effect of the strength,ductility and *** results indicate that the tailings-aggregate ratio of 5:5 and PP fiber content of 0.5 kg/m^(3) are the optimum point considering the UCS,cracking strain,peak strain and post-peak *** tailings-aggregate ratio is consistent with the unary quadratic to the UCS and a linear model with a negative slope to the *** analysis indicates that PP fiber tends to bridge the cracks and rod-mill sand to serve as the skeleton of the paste matrix,which can enhance the compactness and improve the ductility of the *** results presented here are of great significance to the understanding and application of coarse aggregates and fibers to improve the mechanical properties of CTB.

关键词： cemented tailings backfill polypropylene fiber coarse aggregate unconfined compressive strength postpeak ductility fluidity

泾河支流地表水地下水的水化学特征及其控制因素

在线全文

学校读者我要写书评

暂无评论

环境科学 2018年第7期39卷 3142-3149页

作者：寇永朝华琨李洲李志西北农林科技大学资源环境学院杨凌712100

为研究泾河支流(黑河流域)的水化学特征及其控制因素,2014~2015年先后采集枯水期及汛期地表水和地下水的水样242个,综合运用Piper三线图、相关性分析和Gibbs图等方法,分析了黑河流域水化学特征,并探讨了黑河流域的水化学演化规律.结果表... 详细信息

为研究泾河支流(黑河流域)的水化学特征及其控制因素,2014~2015年先后采集枯水期及汛期地表水和地下水的水样242个,综合运用Piper三线图、相关性分析和Gibbs图等方法,分析了黑河流域水化学特征,并探讨了黑河流域的水化学演化规律.结果表明,研究区水体均呈弱碱性,2014年枯水期地表水和地下水阳离子以Na+为主,分别约占阳离子总量的56%和58%;阴离子以SO_4^(2-)为主,分别约占地表水和地下水阴离子总量的33%和39%;其它3个时期主要地表水和地下水组成阴阳离子均以HCO_3^-和Na^+为主,约占阴离子和阳离子总量的44%~46%和42%~56%.枯水期地表水TDS在上中游波动较大,汛期地表水和地下水的TDS由上游到下游沿河道逐渐增加.由枯水期到汛期,地表水的水化学类型由Na-Mg-Cl-SO4型转变为Ca-Mg-HCO3型,地下水由Mg-Cl-SO_4型转变为Ca-Na-HCO_3型.水化学样品点大部分分布在Gibbs图左中上部,说明流域水化学离子形成主要受岩石风化和蒸发-浓缩作用的影响,而人类活动对水化学的影响在枯水期较汛期更显著.

关键词：水化学离子来源相关性分析地表水地下水

First Passage Probability of Structures under Non-Gaussian Stochastic Behavior

在线全文

学校读者我要写书评

暂无评论

Journal of Shanghai Jiaotong university(Science) 2008年第4期13卷 400-403页

作者：何军周拥军寇新建 Department of Civil Engineering School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiaotong University

An analytical moment-based method was proposed for calculating first passage probability of structures under non-Gaussian stochastic behaviour. In the method, the third-moment standardization that con- stants can be obtained from first three-order response moments was used to map a non-Gaussian structural response into a standard Gaussian process; then the mean up-crossing rates, the mean clump size and the initial passage probability of some critical barrier level by the original structural response were estimated. Finally, the formula for calculating first passage probability was established on the assumption that the corrected up-crossing rates are independent. By a nonlinear single-degree-of-freedom system excited by a stationary Gaussian load, it is demonstrated how the procedure can be used for the type of structures considered. Further, comparisons between the results from the present procedure and those from Monte-Carlo simulation are performed.

关键词： first passage probability stochastic process non-Gaussian structures third-moment standardization

在线全文

学校读者我要写书评

暂无评论

四川黄龙沟少花鹤顶兰繁殖成功特征

生态学报 2012年第21期32卷 6795-6802页

作者：黄宝强寇勇安德军南昌工程学院南昌330099 四川省黄龙国家级风景名胜区管理局黄龙624000

少花鹤顶兰(Phaiu delavayi)是多年生、多次结实的具有克隆能力的地生兰科植物,是中国特有种。目前少花鹤顶兰开花物候、花寿命、繁殖成功等生物学特征尚不清楚,而这些资料是开展少花鹤顶兰进化和保护生物学研究的基础。利用2005—2007... 详细信息

少花鹤顶兰(Phaiu delavayi)是多年生、多次结实的具有克隆能力的地生兰科植物,是中国特有种。目前少花鹤顶兰开花物候、花寿命、繁殖成功等生物学特征尚不清楚,而这些资料是开展少花鹤顶兰进化和保护生物学研究的基础。利用2005—2007年四川黄龙沟少花鹤顶兰的调查数据,对少花鹤顶兰繁殖成功特征进行了研究。结果表明黄龙沟少花鹤顶兰每个花序的平均花朵数为3(1—7)朵。叶和花的形态指标在年季间无显著变异。2005—2007年3年间的开花物候没有明显的差异,花期始于6月中旬,于7月底至8月初结束,持续约6—7周,80%—90%的花在7月初的开花高峰期开放,属花集中开放模式。花寿命与是否授粉密切相关,成功授粉的花寿命比没有授粉的花寿命短。少花鹤顶兰是自交亲和的,但其结实完全依赖于两种熊蜂的传粉,不存在自动自花授粉和无融合生殖现象。柱头可授性和花粉活力可维持15 d左右。繁殖成功率年季间的变化很大,并表现出逐年下降的趋势,花粉移走率为18%—51%,自然结实率为10%—36%。繁殖成功下降的趋势可能与黄龙沟喷洒农药有关。

关键词：少花鹤顶兰开花物候花粉移走率结实率繁育系统保护