检索结果-南通市图书馆

生物炭和秸秆还田对咸水滴灌棉田土壤微生物群落特征及功能差异的影响

在线全文

学校读者我要写书评

暂无评论

环境科学 2024年第6期45卷 3571-3583页

作者：郭晓雯向贵琴张发朝江山闵伟石河子大学农学院石河子832003

干旱区淡水资源不足,农业用水主要依赖于含盐的浅层地下水,但长期咸水灌溉会造成土壤盐分积累,土壤环境恶化,不利于作物生长.因此,在长期淡水(0.35 d S·m^(-1),FW)和咸水(8.04 d S·m^(-1),SW)灌溉的基础上,采用等碳量设计向土壤中添... 详细信息

干旱区淡水资源不足,农业用水主要依赖于含盐的浅层地下水,但长期咸水灌溉会造成土壤盐分积累,土壤环境恶化,不利于作物生长.因此,在长期淡水(0.35 d S·m^(-1),FW)和咸水(8.04 d S·m^(-1),SW)灌溉的基础上,采用等碳量设计向土壤中添加生物炭(3.7 t·hm^(-2),BC)和秸秆(6 t·hm^(-2),ST),旨在明晰生物炭和秸秆还田对盐渍化土壤理化性质及微生物群落结构的影响.结果表明,咸水灌溉显著增加土壤含水量、电导率、速效磷和全碳的含量,但显著降低了p H值和速效钾的含量.生物炭和秸秆还田均显著增加土壤含水量、速效磷、速效钾和全碳的含量,但显著降低了咸水灌溉条件下的电导率值.各处理土壤优势菌门为变形菌门、放线菌门、酸杆菌门、绿弯菌门和芽单胞菌门.咸水灌溉显著增加芽单胞菌门和变形菌门的相对丰度,但显著降低酸杆菌门和放线菌门的相对丰度.在淡水灌溉条件下,生物炭还田显著降低绿弯菌门的相对丰度;秸秆还田显著增加变形菌门的相对丰度,但显著降低酸杆菌门、放线菌门、绿弯菌门和芽单胞菌门的相对丰度.在咸水灌溉条件下,生物炭还田显著降低绿弯菌门和芽单胞菌门的相对丰度;秸秆还田显著增加变形菌门的相对丰度,但显著降低酸杆菌门、放线菌门、绿弯菌门和芽单胞菌门的相对丰度.LEf Se分析表明,咸水灌溉降低了土壤微生物的潜在标志物和功能数量;咸水灌溉条件下,生物炭还田增加了土壤微生物的潜在标志物和功能数量;秸秆还田增加土壤微生物的潜在功能数量;秸秆还田增加土壤微生物的潜在标志物和功能数量.RDA结果显示,土壤微生物群落和功能结构与EC_(1∶5)、SWC和p H值显著相关.咸水灌溉会恶化土壤环境,不利于农业生产,其中EC_(1∶5)、SWC和p H值是驱动土壤微生物群落和功能结构变化的重要因子,采用生物炭和秸秆还田可减缓盐分对土壤和作物的危害,为提高农业生产力奠定基础.

关键词：宏基因组生物炭秸秆咸水土壤微生物

在线全文

学校读者我要写书评

暂无评论

水下可重构机器人腿部结构设计与自由度分析

凿岩机械气动工具 2024年第3期50卷 45-52页

作者：申博郭文孝山西水利职业技术学院机电工程系山西太原030032 中国煤炭科工集团太原研究院有限公司山西太原030006 山西天地煤机装备有限公司山西太原030006 煤矿采掘机械装备国家工程实验室山西太原030006

水利工程对水下机器人功能要求多样化,本文以水下可重构机器人为研究对象,研究腿部结构可重构使机器人具有多种移动模式,预期实现一机多用。本文将通过锁死UPS支链中等效球副中的一个转动,重构出3类U*PU支链,分析了各类支链的约束特点,... 详细信息

水利工程对水下机器人功能要求多样化,本文以水下可重构机器人为研究对象,研究腿部结构可重构使机器人具有多种移动模式,预期实现一机多用。本文将通过锁死UPS支链中等效球副中的一个转动,重构出3类U*PU支链,分析了各类支链的约束特点,得出Ⅰ类U*PU支链改变自由度的性质,Ⅱ类改变自由度的方向,Ⅲ类是一种不变自由度支链。基于含Ⅲ类U*PU支链的4-U*PU并联机构,设计水下可重构机器人的腿部结构,使其腿部具有2T2R和1R2T两种运动模式。采用旋量理论研究了腿部结构各运动模式变换过程中的自由度性质,分析机器人可重构性,使其满足爬行和蠕动两种运动需求。

关键词：可重构水下机器人运动副约束螺旋运动螺旋连

高原环境对乘员健康和作业能力影响的研究进展

在线全文

学校读者我要写书评

暂无评论

环境与健康杂志 2024年第6期41卷 560-563页

作者：贺军郭书文李琳郭孝文孔巍兵器工业卫生研究所中国兵器工业集团人-机-环境重点实验室陕西西安710065

我国拥有大面积的高原地域,高原地区自然环境恶劣,具有气压低、含氧量低、气温低、昼夜温差大、紫外线强等气候特点,高原环境下疾病特征与其他地区存在较大差异。目前针对急进高原环境的人员进行了系统的研究,但对于维持高原环境下乘员... 详细信息

我国拥有大面积的高原地域,高原地区自然环境恶劣,具有气压低、含氧量低、气温低、昼夜温差大、紫外线强等气候特点,高原环境下疾病特征与其他地区存在较大差异。目前针对急进高原环境的人员进行了系统的研究,但对于维持高原环境下乘员(泛指高原装甲兵、驻训兵、汽车兵等特殊兵种)作业能力的研究还不够深入。我国高原边境线长而复杂,官兵长期驻留在高原环境下的作业能力受到重点关注。该文综述了目前国内外高原环境对乘员健康和作业能力的影响,并提出高原环境下乘员作业能力的研究方向。

关键词：高海拔乘员作业能力机体健康

Synthesis and Crystal Structure of a One-dimensional Azido-bridged Manganese (II) Compound [Mn(N_3)_2(H_2O)_3·C_6H_(12)N_4]_n

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Structural Chemistry 2006年第2期25卷 135-138页

作者： CHEN Hui WANG wen-guo ZHANG xiao-Feng CHEN Chang-Neng LIU Qiu-Tian State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter The Chinese Academy of Sciences Fuzhou Fujian 350002 China

A new one-dimensional azido-bridged manganese compound has been prepared and structurally characterized by X-ray diffraction. The complex [Mn（N3）2（H2O）3·C6H12N4]n crystallizes in space group Pnma with a = 6.5252 （5）, b = 9.3226（7）, c = 22.2070（15） ,A°, V= 1350.89（17） ,A°^3, Z = 4, Mr = 333.24, Dc = 1.639 g/cm^3, μ = 1.005 mm^-1 and F（000） = 692. The final refinement gave R = 0.0328 and wR = 0.0777 for 1085 observed reflections with I 〉 2σ（I）. The structure contains [Mn（N3）2（H2O）3]n polymeric chains and uncoordinated hexamethylenetetramine （HMTA） molecules with Mn/HMTA molar ratio of 1：1. The Mn atoms are bridged by end-to-end azido ligands to construct one-dimensional zig-zag infinite chains. Each Mn atom is six-coordinated by three N atoms of three azido ligands and three water O atoms, resulting in an octahedral geometry. Extending hydrogenbonding interactions involving water O atoms, azido and HMTA N atoms link the chains and HMTA molecules into a three-dimensional network.

关键词： manganese crystal structure azide coordination polymer

Drying Shrinkage of Cement-Based Materials Under Conditions of Constant Temperature and Varying Humidity

在线全文

学校读者我要写书评

暂无评论

Journal of China University of Mining and Technology 2007年第3期17卷 428-431页

作者： MA Bao-guo wen xiao-dong WANG Ming-yuan YAN Jia-jia Gao xiao-jian Key Laboratory for Silicate Materials Science and Engineering of Ministry of Education Wuhan University of Technology Wuhan Hubei 430070 China

Currently,deformations along the central axis of specimens were usually measured under fixed environmental conditions. Seldom were the effects of environmental factors on the drying-shrinkage deformation of cement-based ma-terial considered. For this paper,the drying-shrinkage deformation at different w/b ratios and different additions to mor-tars was investigated under different environments at a temperature of 20 ℃ and humidity ranging from 100% to 50%. The specimens were cured in water for 28 days before measurement. The results illustrate that mortar shows much less shrinkage under various drying conditions when a lower w/b ratio is adopted. With a decrease in relative humidity the speed of drying-shrinkage becomes gradually lower. The addition of silica fume reduces the drying-shrinkage of mortar under higher relative humidity,because the pore structure of mortar with silica fume becomes more refined. The addi-tion of fly ash increases the total porosity and the volume of coarse pores in the mortar. The drying-shrinkage of mortar under different conditions increases with the addition of more of fly ash.

关键词： humidity variation volume deformation pore structure

The centrosymmetric to non-centrosymmetric transformation induced by alkaline-earth cations producing infrared nonlinear optical AeMn_(6)Ga_(6)S_(16)(Ae=Ca,Sr)

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第9期67卷 2941-2948页

作者： Yang-Ping Zhang Shao-Min Pei wen-Fa Chen Bin-wen Liu xiao-Ming Jiang guo-Cong guo State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China Fuzhou 350108China School of Physical Science and Technology Shanghai Tech UniversityShanghai 201210China

Non-centrosymmetric(NCS)structure is an indispensable prerequisite for second-order nonlinear optical(NLO)***,the mainstream approach for designing new NCS structures still relies on chemical substitution,necessitating an urgent infusion of fresh *** this work,two isomorphic sulfides AeMn_(6)Ga_(6)S_(16)(Ae=Ca,1;Sr,2)are afforded by modifying the skeleton of centrosymmetric(CS)Mn_(2)Ga_(2)S_(5) via introducing strong electropositive alkaline-earth ***,the incorporation of Ca^(2+)/Sr^(2+)cations allows the elementary[MnGaS_(9)]_(∞)chains to reconfigure into bumpy[MnS_(6)]-[GaS_(4)]layers in a new engagement manner,thus enabling the conversion from CS to NCS *** modifications cause not only strong second-harmonic generation(SHG)responses(~1.5×benchmark AgGaS_(2)@1,700 nm),but also significantly feasible bandgaps(2.60-2.64 e V)compared to the sulfide Mn_(2)Ga_(2)S_(5)(1.36 e V),which ultimately facilitate ultrahigh laser-induced damage thresholds(4.4-6.6×AgGaS_(2)@1,064 nm for compounds 1 and 2).The present study offers an ingenious approach for the transformation of CS to NCS structure.

关键词： second-harmonic generation non-centrosymmetrical structure NLO functional motif solid-state method

Object use in insects

在线全文

学校读者我要写书评

暂无评论

Insect Science 2024年第4期31卷 1001-1014页

作者： Chao wen Cai Wang xiaoli guo Hongyu Li Haijun xiao Junbao wen Shikui Dong School of Grassland Science Beijing Forestry UniversityBeijingChina College of Forestry and Landscape Architecture South China Agricultural UniversityGuangzhouChina Beijing Key Laboratory for Forest Pest Control Beijing Forestry UniversityBeijingChina

Insects are the most diverse group of organisms in the animal kingdom,and some species exhibit complex social *** research on insect object use is still in its early stages,insects have already been shown to display rich object-use *** review focuses on patterns and behavioral flexibility in insect object-use behavior,and the role of cultural evolution in the development of object-use *** use in insects is not widespread but has been documented in a diverse set of *** insects can use objects flexibly and display various object-use *** mammals and birds,insects use objects in diverse activities,including foraging,predator defense,courtship,and ***,pre-existing manipulative behaviors,and anatomical structure affect innovations in object *** addition,learning and imitation are the main mechanisms underlying the spread of object-use behaviors within *** that insects are one of the major animal groups engaging in object use,studies of insect object use could provide general insights into object use in the animal kingdom.

关键词： cognition evolution insects learning object use

P-and SV-wave dispersion and attenuation in saturated microcracked porous rock with aligned penny-shaped fractures

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

Petroleum Science 2024年第1期21卷 143-161页

作者： Sheng-Qing Li wen-Hao Wang Yuan-Da Su Jun-Xin guo xiao-Ming Tang School of Geosciences China University of Petroleum(East China)Qingdao 266580ShandongChina Laoshan National Laboratory Qingdao 266071ShangdongChina Guangdong Provincial Key Laboratory of Geophysical High-resolution Imaging Technology Southern University of Science and TechnologyShenzhen 518055GuangdongChina Department of Earth and Space Sciences Southern University of Science and TechnologyShenzhen 518055GuangdongChina

P-and SV-wave dispersion and attenuation have been extensively investigated in saturated poroelastic media with aligned ***,there are few existing models that incorporate the multiple wave attenuation mechanisms from the microscopic scale to the macroscopic ***,in this work,we developed a unified model to incorporate the wave attenuation mechanisms at different scales,which includes the microscopic squirt flow between the microcracks and pores,the mesoscopic wave-induced fluid flow between fractures and background(FB-WIFF),and the macroscopic Biot's global flow and elastic scattering(ES)from the *** Tang's modified Biot's theory and the mixed-boundary conditions,we derived the exact frequency-dependent solutions of the scattering problem for a single penny-shaped fracture with oblique incident P-and *** then developed theoretical models for a set of aligned fractures and randomly oriented fractures using the Foldy *** results indicated that microcrack squirt flow considerably influences the dispersion and attenuation of P-and SV-wave *** coupling effects of microcrack squirt flow with the FB-WIFF and ES of fractures cause much higher velocity dispersion and attenuation for P waves than for SV *** oriented fractures substantially reduce the attenuation caused by the FB-WIFF and ES,particularly for the ES attenuation of SV *** a comparison with existing models in the limiting cases and previous experimental measurements,we validated our model.

关键词： Aligned fractures P-and SV-wave Dispersion and attenuation Microcracked porous background FB-WIFF Elastic scattering Squirt flow

Construction of shRNA of Fulminant Hepatitis Related Gene mfgl2 and Investigation of Its Biological Effects in vitro

在线全文

学校读者我要写书评

暂无评论

中国病毒学 2007年第5期22卷 366-373页

作者： Dong XI Zhi-Mo WANG Sui GAO Chuan-Long ZHU Jian-wen guo xiao-Ping LUO Qin Ning Laboratory of Infectious Immunology Tongji Hospital of Tongji Medical College Huazhong University of Science and Technology Wuhan 430030 China

This study was designed to explore the RNA interference technique in inhibition of the expression of the mouse fibrinogen like protein 2(mfgl2),which has been reported to be involved in the development a variety of diseases including fulminant viral hepatitis.A plasmid named p-mfgl2shRNA,complementary to the sequence of mfgl2 was constructed,while another short hairpin RNA(shRNA) which was a mutated form of the mfgl2shRNA sequences was used as a control.A plasmid named pEGFP-mfgl2 expressing the mfgl2-EGFP fusion protein was also constructed for the screening of the effect of p-mfgl2shRNA on mfgl2 *** cotransfection of p-mfgl2shRNA and pEGFP-mfgl2 or pcDNA3.1-mfgl2 expression construct into CHO cells or HeLa cells,the inhibition of mfgl2 expression by mfgl2shRNA was analyzed by direct observation through fluorescent microscopy,FACS,RT-PCR and immunohistochemistry *** experiments showed the significant inhibitory effect of p-mfgl2shRNA on mfgl2 expression at 48h post-transfection in both CHO and Hela cell lines with the inhibitory efficiency as high as 80.1%.The study demonstrated that the construct of p-mfgl2shRNA successfully interfered with the mfgl2 expression in vitro.

关键词：爆发性肝炎 mfgl2基因 shRNA RNA干涉