检索结果-南通市图书馆

Controls of seed quantity and quality on seedling recruitment of smith fir along altitudinal gradient in southeastern Tibetan Plateau

引用

Journal of Mountain Science 2016年第5期13卷 811-821页

作者： WANG Jing-sheng FENG Ji-guang CHEN Bao-xiong SHI Pei-li ZHANG Jun-long FANG Jiang-ping WANG Zhi-kai YAO Shuai-chen ding Lu-bin Lhasa Plateau Ecosystem Research Station Key Laboratory of Ecosystem Network Observation and ModelingInstitute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China School of Environment and Natural Resources Renmin University of ChinaBeiing 100872China Rural Energy&Environment Agency Ministry of Agriculture of the People's Republic of ChinaBeijing 100125China National Center for Climate Change Strategy and International Cooperation Beijing 100038China TibetAgricultural andAnimal Husbandry College Tibet Linzhi 860000China

Alpine treeline ecotones are harsh environment for tree establishment due to low temperature. Tree establishment at treelines requires favorable climate, suitable microsites, and viable seeds. But most researches have been addressed treeline microclimate and its effects on tree regeneration, the knowledge of seed quantity and quality and its controls on seedling recruitment were limited. We measured seed rain, soil seed bank, seed germination rate and seedling recruitment in natural forests in combination with seed transplanting manipulation to evaluate the controls of seed quantity and quality on seedling recruitment of Abies georgei var. smithii （smith fir） along altitudinal gradient, with focus on treeline ecotone in the Sygera Mountains, southeastern Tibetan Plateau. Both seed quantity and seed quality of smith fir decreased with increasing altitude and was thereby associated with decline in seed germination rate. Seed quantity and seedling recruitment were better in north-facing slope than in south slope. The treeline ecotone above 42oo m appeared as the threshold altitude to sharply decrease seed quality and seedling recruitment. The emergence and overwintering rates of transplanting seeds from 3600-38oo m also went down remarkably above 4200 m at north-facing slope. It also underpins the fact that treeline ecotone is the bottleneck of seedling recruitment. Our results suggest that seed quantity and quality are the principal limitation of treeline upward advance. This study also provides evidence to support stable treeline position in southeastern Tibetan Plateau.

关键词： Abies georgei var. smithii Treeline Seed rain Soil seed bank Seed quality Seedling recruitment

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

用相对论平均场理论研究近滴线区原子核传统幻数的消失和新幻数的产生

引用

物理学报 2007年第12期56卷 6905-6910页

作者：丁斌刚鲁定辉张大立湖州师范学院理学院湖州313000 浙江大学近代物理中心杭州310027

提出了一种从理论上检验壳效应的方法.在考虑了由Bardeen,Cooper和Schrieffer提出的金属超导理论(BCS方法)的相对论平均场理论框架内,通过计算粒子数的涨落,发现涨落的大小和核的壳结构有紧密的关系,进而研究了滴线区一些传统幻数的消... 详细信息

提出了一种从理论上检验壳效应的方法.在考虑了由Bardeen,Cooper和Schrieffer提出的金属超导理论(BCS方法)的相对论平均场理论框架内,通过计算粒子数的涨落,发现涨落的大小和核的壳结构有紧密的关系,进而研究了滴线区一些传统幻数的消失和新幻数的产生.

关键词：相对论平均场理论粒子数涨落幻数壳效应

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Bamboo leaf extract improves spatial learning ability in a rat model with senile dementia

引用

Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2015年第7期16卷 593-601页

作者： Jian-xiang LIU Min-ying ZHU Ci-yuan FENG Hai-bin ding Ying ZHAN Zhan ZHAO Yue-min ding Department of Clinical Medicine School of Medicine Zhejiang University City College

Senile dementia（SD） is a syndrome characterized by progressive neurological deterioration. Treatment for the disease is still under investigation. Bamboo leaf extract（B-extract） has been known for its biological efficacy in anti-oxidant and anti-cancer activities. However, study on B-extract for its protection against dementia is very limited. The effect of B-extract on a rat model with SD was examined. B-extract improved spatial learning ability of the dementia rats. The hippocampus of dementia model rats showed reduced levels of acetylcholine（ACh）, epinephrine（E）, norepinephrine（NE）, and dopamine（DA）, and increased activities of acetylcholine esterase（ACh E） and monoamine oxidase（MAO）. Treatment with B-extract 20 mg/（kg·d） for 7 weeks significantly inhibited the enzyme activity compared with untreated dementia rats, and raised the levels of ACh, E, and DA in the hippocampus. In addition, treatment with B-extract elevated the level of γ-aminobutyric acid（GABA）, but reduced the level of glutamate（Glu） in the brain. These data suggest that B-extract might be a potential drug in treating impairment of spatial memory in dementia rats by regulating the central neurotransmitter function.

关键词： Bamboo leaf extract Dementia Alzheimer's disease Neurotransmitter

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Mechanism of expanding swept volume by nano-sized oil-displacement agent

引用

Petroleum Exploration and Development 2019年第5期46卷 991-997页

作者： LEI Qun LUO Jianhui PENG Baoliang WANG Xiaocong XIAO Peiwen WANG Pingmei HE Lipeng ding bin GENG Xiangfei Research Institute of Petroleum Exploration&Development PetroChinaBeijing 100083China Key Laboratory of Nano Chemistry(KLNC) CNPCBeijing 100083China

The effect of expanding swept volume by iNanoW1.0 nanoparticles in ultra-low permeability core was studied by low-field nuclear magnetic resonance(LF-NMR)technology,and the mechanism of expanding swept volume was explained by oxygen spectrum nuclear magnetic resonance(17O-NMR)experiments and capillarity *** results of the LF-NMR experiment show that the nano-sized oil-displacement agent iNanoW1.0 could increase the swept volume by 10%-20%on the basis of conventional water flooding,making water molecules get into the low permeable region with small pores that conventional water flooding could not reach.17O-NMR technique and capillary analysis proved that iNanoW1.0 nanoparticles could weaken the association of hydrogen bonds between water molecules,effectively change the structure of water molecular clusters,and thus increasing the swept volume in the low permeable *** ability of weakening association of hydrogen bonds between water molecules of iNanoW1.0 nanoparticles increases with its mass fraction and tends to be stable after the mass fraction of 0.1%.

关键词： nanoparticles nano-sized oil-displacement agent water flooding swept volume water molecular hydrogen bonding capillary action

来源：

维普期刊数据库

同方期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Green Tea Polyphenols Attenuate High-Fat Diet-Induced Renal Oxidative Stress through SIRT3-Dependent Deacetylation

引用

Biomedical and Environmental Sciences 2015年第6期28卷 455-459页

作者： YANG Hui ZUO Xue Zhi TIAN Chong HE Dong Liang YI Wei Jie CHEN Zhuo ZHANG Pi Wei ding Shi bin YING Chen Jiang Department of Nutrition and Food Hygiene School of Public HealthTongji Medical CollegeHuazhong University of Science and Technology Tongji Hospital Tongji Medical CollegeHuazhong University of Science and Technology School of Nursing Tongji Medical CollegeHuazhong University of Science and Technology Department of Nutrition and Food Hygiene School of Public HealthXinxiang Medical College

Fifty male Wistar rats were fed a standard chow diet or a high-fat （HF） diet, and different concentrations of green tea polyphenols （GTPs）（0.8, 1.6, and 3.2 g/L） were administered in the drinking water. We found that the malondialdehyde （MDA） level in the HF diet group was significantly higher than that in the control （CON） group （P〈0.05）. Decreased peroxisome proliferato r-activated receptor （PPAR）-α and sirtuin 3 （SlRT3） expression, and increased manganese superoxide dismutase （MnSOD） acetylation levels were also detected in the HF diet group （P〈0.05）. GTP treatment upregulated SlRT3 and PPARa expression, increased the ppora mRNA level, reduced the MnSOD acetylation level, and decreased MDA production in rats fed a HF diet （P〈0.05）. No significant differences in total renal MnSOD and PPAR-y coactivator-1α （PGCI-α） expression were detected. The reduced oxidative stress detected in kidney tissues after GTP treatment was partly due to the higher SIRT3 expression, which was likely mediated by PPARα.

关键词： polyphenols drinking PPAR Figure mitochondria metabolism superoxide peroxisome oxidative homeostasis

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

基于合作博弈的预付条件下应急物资库存策略

引用

运筹与管理 2011年第3期20卷 60-65页

作者：丁斌桂斌中国科学技术大学管理学院安徽合肥230026

应急物资储备是应急管理的主要工作之一。以往政府自己组织物资储备,不仅耗费大量人力、物力,且由于应急物资具有有效期等缘故,报废损失较大。本文考虑政府与供应商合作进行应急物资的实物储备,讨论在政府提前支付部分货款、供应商储备... 详细信息

应急物资储备是应急管理的主要工作之一。以往政府自己组织物资储备,不仅耗费大量人力、物力,且由于应急物资具有有效期等缘故,报废损失较大。本文考虑政府与供应商合作进行应急物资的实物储备,讨论在政府提前支付部分货款、供应商储备应急物资的库存策略,并从合作博弈的角度,确立了联盟的合作期限与政府提前支付货款比例,实现了在减少政府支出的前提下,动态存储定量应急物资,大幅度延长有效期的目标。最后使用算例验证了该策略的有效性。

关键词：管理科学库存策略合作博弈提前支付应急物资

来源：

维普期刊数据库

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

空中交通管制人员风险评价的证据理论模型

引用

系统仿真学报 2007年第15期19卷 3368-3371页

作者：丁松滨石荣中国民航大学无人机研究所天津300300 中国民航飞行学院飞行技术学院四川广汉618307

针对空中交通管制人员风险评价中的不确定性问题,基于证据理论建立了空中交通管制人员风险评价指标体系和空中交通管制人员的风险评价模型,并提出了具体的算法,通过仿真实例计算,验证了该方法能较好地解决评价过程中所遇到的不确定性问题。

关键词：空中交通管制风险评价不确定性证据理论

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

基于双目视觉的激光位移传感器标定方法

引用

浙江大学学报（工学版） 2021年第9期55卷 1634-1642页

作者：马浩然丁雅斌天津大学机械工程学院天津300350

为了提高激光位移传感器在工业机器人末端坐标系下的标定精度,提出基于双目视觉的激光位移传感器标定方法.该方法通过双目视觉技术重建激光光束投影在平面上的光斑位置,利用手眼标定参数将光斑位置转换至机器人末端坐标系,同时利用最小... 详细信息

为了提高激光位移传感器在工业机器人末端坐标系下的标定精度,提出基于双目视觉的激光位移传感器标定方法.该方法通过双目视觉技术重建激光光束投影在平面上的光斑位置,利用手眼标定参数将光斑位置转换至机器人末端坐标系,同时利用最小二乘方法将光斑拟合成光束直线,获得机器人末端坐标系下的传感器光束方向及零点位置以完成标定.该方法可同时标定机器人末端上的多个激光位移传感器,无须采用有精度要求的辅助工件标定,具备精度高,鲁棒性强优势.基于标准球的精度评价实验结果显示,在3倍标准差范围内该方法标定后的激光位移传感器测量精度范围为0.0386±0.0258 mm,满足机器人加工要求.

关键词：双目视觉系统激光位移传感器测量系统传感器标定工业机器人

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Association of VCAM-1 overexpression with oncogenesis,tumor angiogenesis and metastasis of gastric carcinoma

引用

World Journal of Gastroenterology 2003年第7期9卷 1409-1414页

作者： Yong-bin ding Guo-Yu Chen Jian-Guo Xia Xi-Wei Zang Hong-Yu Yang Li Yang Department of General Surgery,the First Affiliated Hospital of Nanjing Medical University,Nanjing 210029,Jiangsu Province,China Department of General Surgery the First Affiliated Hospital of Nanjing Medical University Nanjing 210029 Jiangsu Province China. njdyb@***

AIM: To investigate the relationship between the expression of vascular cell adhesion molecule-1 (VCAM-1) and oncogenesis,tumor angiogenesis and metastasis in gastric carcinoma,and to evaluate the clinical significance of serum VCAM-1levels in gastric ***: Specimens from 41 patients with gastric cancer, 8 patients with benign gastric ulcer, and 10 healthy subjects were detected for the expression of VCAM-1 by immunohistochemistry. Microvessel density (MVD) was measured by counting the endothelial cells immunostained with the monoclonal antibody CD34 at x200 *** VCAM-1 concentrations were measured by an enzyme linked immunosorbent assay in the 41 gastric cancer patients before surgery, and at 7 days after surgery as well as in 25 healthy controls. The association between preoperative serum VCAM-1 levels and clinicopathological features, and their changes following surgery was evaluated. Tn addition, serum carcinoembryonic antigen (CEA) was also ***: Of the 41 gastric cancer tissues, 31 (75.6 %)were VCAM-1 positive. The VCAM-1 positive gastric cancers were more invasive and classified in the more advanced stage than the VCAM-1 negative ones. The VCAM-1 positive cancers were associated with more lymph node metastases than VCAM-1-negative ones (P＜0.05). The expression of VCAM-1 was detected in tissues of two of the eight patients with gastric ulcer and two of the 10 healthy controls. The expression of VCAM-1 in gastric cancer patients was significantly more frequent than that in the healthy controls and ulcer group (both P＜0.05). MVD in VCAM-1 expressing tissues was higher than that in VCAM-1 negative tissues (t=2.13,P＜0.05). Serum VCAM-1 levels in gastric cancer patients were significantly higher than those in controls (t=3.4, P＜0.05). There was a significant association between serum VCAM-1 levels and disease stage, as well as invasion depth of the tumor and the presence of distant *** concentrations of serum CEA in g

关键词：血管细胞粘附分子-1 肿瘤形成血管生成肿瘤转移胃癌

来源：

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

PREPARATION OF Fe_3O_4/PSt MAGNETIC PARTICLES IN THE PRESENCE OF MAGNETIC FLUID IN ETHANOL/WATER MIXTURE

引用

Chinese Journal of Polymer Science 1999年第2期17卷 129-134页

作者： Xiao-bin ding Zong-hua Sun Guo-xiang Wan Ying-yan Jiang Chengdu Institute of Organic Chemistry, Chinesc Academy of Sciences, Chengdu 610041, China Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China Chengdu Institute of Organic Chemistry Chinese Academy of Sciences Chengdu 610041 China Institute of Chemistry Chinese Academy of Sciences Beijing 100080 China

Fe_3O_4/Polystyrene(PSt) magnetic particles with core/shell structure have been prepared in thepresence of Fe_3O_4 magnetic fluid in ethanol/water medium by dispersion polymeriation of styrene. A Fe_3O_4particle formation mechanism was proposed. According to this mechanism, the size of particle nuclei isdetermined by the extent of aggregation of Fe_3O_4 /oligomer. Magnetic particles with diameter ranging from 5to 200 μm were prepared under different reaction conditions. Some polymerization parameters such as theconcentration of monomer, stabilizer, initiator, and ethanol which affect particle size and size distribution arediscussed and their effect on particle formation are explained by the proposed mechanism.

关键词： Fe_3O_4 magnetic fluid Magnetic particle Polystyrene Polymerization Mechanism

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：