期刊文献+
共找到440篇文章
< 1 2 22 >
每页显示 20 50 100
Genesis Types and Diagenesis Compaction Mechanisms of Sandstone Rreservoirs in Dynamic Environments in Oil/Gas Basins in China 被引量:7
1
作者 Shou Jianfeng Si Chunsong Wang Xin 《Petroleum Science》 SCIE CAS CSCD 2006年第3期23-31,共9页
The diversity of sandstone diagenesis mechanisms caused by the complex geological conditions of oil/gas basins in China could hardly be reasonably explained by the traditional concept of burial diagenesis. Three genes... The diversity of sandstone diagenesis mechanisms caused by the complex geological conditions of oil/gas basins in China could hardly be reasonably explained by the traditional concept of burial diagenesis. Three genesis types of thermal diagenesis, tectonic diagenesis and fluid diagenesis are presented on the basis of the dynamic environment of the oil/gas basins and.the controlling factors and mechanisms of sandstone diagenesis. Thermal diagenesis of sandstone reservoirs is related not only to the effect of formation temperature on diagenesis, but also to the significant changes in diagenesis caused by geothermal gradients. The concept of thermal compaction is presented. Thermal compaction becomes weaker with increasing depth and becomes stronger at a higher geothermal gradient. At the same formation temperature, the sandstone porosity in the region with a lower geothermal gradient is e^0.077+0.0042T times higher than that in the region with a higher geothermal gradient. Both sudden and gradual changes are observed in diagenetic evolution caused by structural deformation. Average sandstone compaction increased by 0.1051% for every 1.0MPa increase of lateral tectonic compressional stress, while late tectonic napping helped to preserve a higher porosity of underlying sandstone reservoir. Fluid diagenesis is a general phenomenon. The compaction caused by fluid properties is significant. The coarser the grain size, the stronger the fluid effect on compaction. The greater the burial depth, the weaker the fluid effect on compaction for the specific reservoir lithology and the greater the difference in the fluid effects on compaction between different grain sizes. 展开更多
关键词 Oil/gas basins in China sandstone reservoir genesis types diagenesis compaction mechanism
下载PDF
密度和行距对直立株型小麦产量、群体冠层特征和抗倒伏性的影响
2
作者 赵夕冉 张玉 +6 位作者 张嘉豪 陈建省 张卫东 马玉华 孟庆福 鄢照新 汪永振 《中国农学通报》 2024年第14期13-22,共10页
为了给直立株型小麦的栽培措施调控提供理论依据,本研究以2个小麦直立株型品系‘SN1319’和‘SN1425’为试验材料,设置T1(330×104株/hm^(2)基本苗)和T2(420×104株/hm^(2)基本苗)2个高密度播量,H1、H2和H3(分别为1.10 m播幅6... 为了给直立株型小麦的栽培措施调控提供理论依据,本研究以2个小麦直立株型品系‘SN1319’和‘SN1425’为试验材料,设置T1(330×104株/hm^(2)基本苗)和T2(420×104株/hm^(2)基本苗)2个高密度播量,H1、H2和H3(分别为1.10 m播幅6行,8行和10行)3个行距组合,研究种植方式对小麦产量、冠层特征和倒伏特性的影响。结果表明,‘SN1319’和‘SN1425’分别在T2H2和T2H3处理下获得最高产量,比对照‘济麦22’增产9.83%和10.10%;高密度条件改善了小麦冠层形态特征,增加叶面积指数(LAI)和消光系数(EC),提高了小麦冠层光截获能力;但是使群体透光性(LT)下降,倒伏指数(LI)上升。品系、行距对冠层结构、光截获能力以及倒伏特性也具有显著影响。试验表明420×104株/hm^(2)基本苗、适当缩小行距可作为直立株型小麦合理的栽培措施。直立株型小麦作为一种新的类型,能够选育高产甚至超高产小麦品系,在实践中具有应用价值。 展开更多
关键词 普通小麦 紧凑株型 播量 行距 产量 冠层结构 抗倒伏性
下载PDF
云南省地级城市近20年空间格局演变
3
作者 张娇 杨勇 +2 位作者 周芹芳 马品 毛峰 《国土与自然资源研究》 2024年第1期42-47,共6页
以云南省16个地级城市为研究区域,基于2000-2017年6个时间段的遥感影像、GDP、人口等数据,通过城市面积、扩展面积、扩展速度、扩展强度、用地增长弹性系数、空间扩展类型、紧凑度等7个评价指标来揭示云南省近20年城市扩展空间演变规律... 以云南省16个地级城市为研究区域,基于2000-2017年6个时间段的遥感影像、GDP、人口等数据,通过城市面积、扩展面积、扩展速度、扩展强度、用地增长弹性系数、空间扩展类型、紧凑度等7个评价指标来揭示云南省近20年城市扩展空间演变规律。结果表明,(1)空间格局上,在这17年间城区规模呈直线攀升,且城市扩展呈现出明显阶段性和地域差异性。(2)用地效益上,城市用地增长弹性系数均大于最优值,城市土地的扩展远大于城市人口的增长,二者出现不协调。(3)扩展类型上,在2000-2010年基本为外延型扩展,2011-2017年内部填充型扩展城市增多。(4)空间形态上,城市紧凑度呈现出“西高东低”的特征,而时间进程上表现为西南部地区先降后升,东部地区逐渐提升。 展开更多
关键词 空间格局 紧凑度 凸壳原理 扩展模式 云南省
下载PDF
从Bloch-type空间到Bers-type空间的复合算子
4
作者 普昭年 《沈阳师范大学学报(自然科学版)》 CAS 2012年第2期145-148,共4页
一个线性算子把有界集映为有界集,则称它为有界的;若一个线性算子把有界集映为有紧闭包的集合,则称它是紧的。在解析函数空间中,感兴趣的是找出解析映射所诱导的有界算子或紧算子的函数理论特征。主要给出了从Bloch-type空间到Bers-typ... 一个线性算子把有界集映为有界集,则称它为有界的;若一个线性算子把有界集映为有紧闭包的集合,则称它是紧的。在解析函数空间中,感兴趣的是找出解析映射所诱导的有界算子或紧算子的函数理论特征。主要给出了从Bloch-type空间到Bers-type空间及小Bers-type空间的复合算子有界和紧的充要条件。 展开更多
关键词 Bloch-type空间 Bers-type空间 复合算子 有界性 紧性
下载PDF
鸡鸣口引水枢纽坝型比选研究
5
作者 万珍 《山东水利》 2024年第3期46-48,共3页
根据鸡鸣口引水枢纽地形地质条件等基本资料,对自密实块石混凝土拱坝、混凝土重力坝和混凝土闸坝3种坝型方案进行技术经济比较,依据比较结果,推荐鸡鸣口引水枢纽采用自密实块石混凝土拱坝坝型。
关键词 鸡鸣口水电站 坝型比选 自密实块石混凝土拱坝
下载PDF
从Zygmund空间到Bloch-type空间的加权复合算子 被引量:2
6
作者 邹堃 谭海鸥 《青岛理工大学学报》 CAS 2010年第5期105-108,共4页
令φ,u分别是复平面C上的单位开圆盘D中的解析自映射和解析函数.加权复合算子定义为(uCφ)(f)(z)=u(z)f(φ(z)),z∈D,f∈H(D).主要讨论了从Zygmund空间到Bloch-type空间的加权复合算子的有界性和紧性.
关键词 加权复合算子 ZYGMUND空间 Bloch-type空间 有界性 紧性
下载PDF
COMPOSITION OPERATOR ON BERS-TYPE SPACES 被引量:6
7
作者 何维湘 姜立建 《Acta Mathematica Scientia》 SCIE CSCD 2002年第3期404-412,共9页
Necessary and sufficient conditions are established for a composition operator C(phi)f = f o phi to be bounded or compact on the Bers-type space H-alpha(infinity) and the little Bers-type space H-alpha(infinity). The ... Necessary and sufficient conditions are established for a composition operator C(phi)f = f o phi to be bounded or compact on the Bers-type space H-alpha(infinity) and the little Bers-type space H-alpha(infinity). The boundedness and compactness of the composition operator C-phi on A(infinity)(phi) are characterized, which generalize the case of C-phi on H-alpha(infinity). 展开更多
关键词 composition operator Bers-type space BOUNDEDNESS compactNESS
下载PDF
WADiana Compact全自动血型分析仪常见故障及排除 被引量:2
8
作者 郑卫东 王娟 吴颖 《医疗卫生装备》 CAS 2019年第4期103-105,共3页
介绍了WADiana Compact全自动血型分析仪的工作原理,详细分析了该仪器使用中出现的血液样本中存在凝块、试剂量不足、机械臂不能移动、压力和/或真空不足、凝胶卡无法识别、样本条码无法识别等故障并提出了具体的排除方法,最后指出了正... 介绍了WADiana Compact全自动血型分析仪的工作原理,详细分析了该仪器使用中出现的血液样本中存在凝块、试剂量不足、机械臂不能移动、压力和/或真空不足、凝胶卡无法识别、样本条码无法识别等故障并提出了具体的排除方法,最后指出了正确使用和定期保养对于延长仪器寿命的重要意义,为同行维修同类设备提供了参考。 展开更多
关键词 WADiana compact全自动血型分析仪 故障现象 故障排除 血型鉴定
下载PDF
COMPOSITION OPERATORS BETWEEN BLOCH TYPE SPACES IN THE UNIT BALL 被引量:3
9
作者 戴济能 欧阳才衡 《Acta Mathematica Scientia》 SCIE CSCD 2014年第1期73-81,共9页
In this paper, we obtain some new necessary and sufficient conditions for the boundedness and compactness of composition operators Cφ between Bloch type spaces in the unit ball Bn.
关键词 composition operator Bloch type space BOUNDEDNESS compactNESS
下载PDF
COMPOSITION TYPE OPERATORS FROM HARDY SPACES TO μ-BLOCH SPACES ON THE UNIT BALL 被引量:2
10
作者 王雄亮 刘太顺 《Acta Mathematica Scientia》 SCIE CSCD 2009年第5期1430-1438,共9页
Let φ be a holomorphic self-map of Bn and ψ ∈ H(Hn). A composition type operator is defined by Tψ,φ(f) = ψf o φ for f ∈ H(Bn), which is a generalization of the multiplication operator and the composition... Let φ be a holomorphic self-map of Bn and ψ ∈ H(Hn). A composition type operator is defined by Tψ,φ(f) = ψf o φ for f ∈ H(Bn), which is a generalization of the multiplication operator and the composition operator. In this article, the necessary and sufficient conditions are given for the composition type operator Tψ,φ to be bounded or compact from Hardy space HP(Bn) to μ-Bloch space Bμ(Bn). The conditions are some supremums concerned with ψ,φ, their derivatives and Bergman metric of Bn. At the same time, two corollaries are obtained. 展开更多
关键词 Hardy spaces μ-Bloch spaces composition type operators BOUNDEDNESS compactNESS
下载PDF
Composition-integral Type Operators from F(p, q, s) Spaces to Bloch-type Spaces 被引量:2
11
作者 LV Xiao-fen YING Shao-hong 《Chinese Quarterly Journal of Mathematics》 CSCD 2012年第3期352-356,共5页
This paper deals with the boundedness and compactness of the compositionintegral type operators T g, from F (p, q, s) spaces to(little) Bloch-type spaces in the unit ball of C n , where Tg,φf(z) =∫01fφ(tz)Rg(tz)(dt... This paper deals with the boundedness and compactness of the compositionintegral type operators T g, from F (p, q, s) spaces to(little) Bloch-type spaces in the unit ball of C n , where Tg,φf(z) =∫01fφ(tz)Rg(tz)(dt)/t , z ∈ B, g ∈ H(B) and φ∈H(B, B). 展开更多
关键词 F (p q s) space Bloch-type space BOUNDEDNESS compactNESS
下载PDF
Weighted Differentiation Composition Operators from Mixed-norm Spaces to Bloch-type Spaces 被引量:1
12
作者 LIU Guang-rong 《Chinese Quarterly Journal of Mathematics》 2015年第2期236-243,共8页
The boundedness and compactness of the weighted differentiation composition operators from mixed-norm spaces to Bloch-type spaces are discussed in this paper.
关键词 mixed-norm spaces Bloch-type spaces BOUNDEDNESS compactNESS
下载PDF
Identification of compact germplasm resources suitable for high density cultivation in Brassica napus L. 被引量:1
13
作者 Wenxiang Wang Qiong Hu +5 位作者 Desheng Mei Jun Wang Hongtao Cheng Hui Wang Li Fu Jia Liu 《Oil Crop Science》 2018年第1期33-41,共9页
Branch angle is an important plant architecture trait and is considerably important for the ideal plant architecture of high density cultivation of rapeseed. In this study,12 representative rapeseed lines were first m... Branch angle is an important plant architecture trait and is considerably important for the ideal plant architecture of high density cultivation of rapeseed. In this study,12 representative rapeseed lines were first measured for whole-plant branch angles using image processing technology. Top branch angle (TBA) and basal branch angle (BBA) were significantly different in each line in which TBA was greater than BBA. Then, 156 rapeseed germplasm lines were evaluated for TBA and BBA in main cultivated regions of the Yangtze River Basin (Zunyi; Wuhan; Lu'an). In these three environments, the TBA and BBA of the rapeseed germplasm sources varied, in which ranges of 33.44°-73.17°and 18.73°-59.11°, 29.66°-61.91°and 22.32°-60.16°, and 28.47°-76.32°and 22.98°-72.68°, respectively. ANOVA showed that TBA and BBA were susceptible to environmental and had broadsense heritability (H2) values of 89.09%and 87.40%, respectively. Interactions of genotype by environment were also significant. There was diversity in branch angle among rapeseed genotypes. GGE biplot analysis showed that compact accession lines (Nilla, Purler and AV-SAPPHI) were the most desirable compact genotypes in all environments. Stability analysis showed that the genotype with the most minimum branch angle was stable for compact plant architecture. 展开更多
关键词 RAPESEED branch angle GERMPLASM diversity compact plant type GGE BIPLOT
下载PDF
北赵灌区皇甫渡槽选型优化设计
14
作者 张娜 王汉明 《水利水电工程设计》 2024年第2期18-22,共5页
皇甫渡槽位于山西省北赵灌区黄土台塬上,地形切割强烈,且为强湿陷性黄土,边坡极易垮塌,常规渡槽设计极易因边坡垮塌造成主体结构损坏,因此需要对渡槽结构进行优化设计。通过静动力仿真分析多次调算,确定为下承式钢管混凝土拱式渡槽。主... 皇甫渡槽位于山西省北赵灌区黄土台塬上,地形切割强烈,且为强湿陷性黄土,边坡极易垮塌,常规渡槽设计极易因边坡垮塌造成主体结构损坏,因此需要对渡槽结构进行优化设计。通过静动力仿真分析多次调算,确定为下承式钢管混凝土拱式渡槽。主拱肋采用预制变截面矩形钢管,通过纵向连梁和风撑组成空间结构体系,主拱肋矩形钢管内灌注自密实微膨胀混凝土;主拱肋拱圈下部等截面钢箱连梁结构;钢箱连梁与拱圈之间采用预应力钢绞线联系;过水钢管桥面系采用工字钢+槽钢横联的连续组合结构;拱圈与纵向钢箱刚结,拱圈在拱座处刚结;两岸采用拱座基础+摩擦型灌注桩型式。该设计方法结合了常规渡槽和管桥方式,降低了结构自重,规避了滑坡损坏结构的风险。本设计成果为水利行业类似不良地质条件大跨径拱式渡槽的设计与施工提供参考,进一步推动大跨径拱槽(桥)的发展。 展开更多
关键词 黄河高阶地 湿陷性黄土 下承式 钢管混凝土拱桥 自密实微膨胀混凝土
下载PDF
550kV GIS盆式绝缘子小型化设计(三)——缩比结构验证 被引量:3
15
作者 王超 李文栋 +3 位作者 陈俊鸿 李金殊 宫瑞磊 张冠军 《电工技术学报》 EI CSCD 北大核心 2023年第7期1970-1981,共12页
为制造经小型化设计的550 kV盆式绝缘子并验证其电气性能,采用3D打印结合环氧树脂浇注工艺制备了1:10缩比绝缘子。首先,将氧化铝填料与光敏树脂复合作为低相对介电常数(3.98~4.20)3D打印浆料,根据光固化与流变特性确定填料含量及打印参... 为制造经小型化设计的550 kV盆式绝缘子并验证其电气性能,采用3D打印结合环氧树脂浇注工艺制备了1:10缩比绝缘子。首先,将氧化铝填料与光敏树脂复合作为低相对介电常数(3.98~4.20)3D打印浆料,根据光固化与流变特性确定填料含量及打印参数后,利用立体光固化3D打印机制备低介电常数的绝缘子主体。随后,将二氧化钛填料与环氧树脂复合作为高相对介电常数(11.32~14.58)真空浇注浆料,浇注至3D打印绝缘子预留的高介电常数区域内,加热固化完成缩比绝缘子的制造。0.2 MPa下SF6氛围中的工频耐压实验结果表明,优化后的绝缘结构具有更优的绝缘强度。相同绝缘距离下,几何形状优化绝缘子闪络电压较常规绝缘子提高13.6%,几何形状/介电分布联合优化的绝缘子提高13.8%;绝缘距离减少15%后,联合优化绝缘子耐电强度与常规绝缘子相当;当法兰侧“楔形”气隙内存在金属丝时,相同绝缘距离下,仅进行形状优化的绝缘子耐电强度提升幅度降低至6.7%,而联合优化绝缘子由于在法兰侧形成低电场区域,闪络电压仍可提高13.1%。结果表明,几何形状/介电分布联合优化绝缘子具有显著的绝缘优势。 展开更多
关键词 气体绝缘金属封闭开关设备(GIS) 盆式绝缘子 小型化 3D打印 沿面闪络
下载PDF
Composition Operator from Logarithmic Bloch-Type Space to Bergman Space on Unit Polydisc
16
作者 张利 曾红刚 《Transactions of Tianjin University》 EI CAS 2011年第6期450-453,共4页
In order to investigate the boundedness or compactness of composition operator from the logarithmic Bloch-type space to the Bergman space on the unit polydisc, the classic Bergman norm is firstly changed into another ... In order to investigate the boundedness or compactness of composition operator from the logarithmic Bloch-type space to the Bergman space on the unit polydisc, the classic Bergman norm is firstly changed into another equivalent norm. Then according to some common inequalities, the properties of logarithmic Bloch-type space and the absolute continuity of the general integral, the conditions which the symbol map must meet when the composition operator is bounded or compact are obtained after a series of calculations, and the boundedness and compactness are proved to be equivalent. 展开更多
关键词 BERGMAN空间 复合算子 多圆柱 单位 对数 绝对连续性 有界性 紧凑性
下载PDF
EXISTENCE OF GLOBAL L~∞ SOLUTIONS TO A GENERALIZED n × n HYPERBOLIC SYSTEM OF LEROUX TYPE
17
作者 刘树君 陈芳启 王泽军 《Acta Mathematica Scientia》 SCIE CSCD 2018年第3期889-897,共9页
In this article, we give the existence of global L∞bounded entropy solutions to the Cauchy problem of a generalized n × n hyperbolic system of Le Roux type. The main difficulty lies in establishing some compactn... In this article, we give the existence of global L∞bounded entropy solutions to the Cauchy problem of a generalized n × n hyperbolic system of Le Roux type. The main difficulty lies in establishing some compactness estimates of the viscosity solutions because the system has been generalized from 2×2 to n×n and more linearly degenerate characteristic fields emerged, and the emergence of singularity in the region {v1= 0} is another difficulty.We obtain the existence of the global weak solutions using the compensated compactness method coupled with the construction of entropy-entropy flux and BV estimates on viscous solutions. 展开更多
关键词 Conservation laws hyperbolic system Le Roux type viscosity method compensated compactness
下载PDF
APPROXIMATION BY COMPLEX SZSZ-DURRMEYER OPERATORS IN COMPACT DISKS 被引量:2
18
作者 Sorin G.GAL Vijay GUPTA 《Acta Mathematica Scientia》 SCIE CSCD 2014年第4期1157-1165,共9页
In the present paper, we deal with the complex Szasz-Durrmeyer operators and study Voronovskaja type results with quantitative estimates for these operators attached to analytic functions of exponential growth on comp... In the present paper, we deal with the complex Szasz-Durrmeyer operators and study Voronovskaja type results with quantitative estimates for these operators attached to analytic functions of exponential growth on compact disks. Also, the exact order of approximation is found. 展开更多
关键词 complex Szasz-Durrmeyer operators Voronovksaja type result exact order of approximation in compact disks simultaneous approximation
下载PDF
基因编辑技术改良玉米株型增加杂交种产量 被引量:2
19
作者 石佳鑫 刘凯 +3 位作者 朱金洁 祁显涛 谢传晓 刘昌林 《生物技术通报》 CAS CSCD 北大核心 2023年第8期62-69,共8页
玉米紧凑株型能够通过密植栽培实现增产。改良玉米株型的关键性状叶夹角,创制紧凑株型的玉米杂交种,能够实现该增产过程。通过基因编辑技术和DTM(desire targeted mutation)策略,突变杂交种中单88的母本CX1的叶夹角形成关键基因ZmLG1,... 玉米紧凑株型能够通过密植栽培实现增产。改良玉米株型的关键性状叶夹角,创制紧凑株型的玉米杂交种,能够实现该增产过程。通过基因编辑技术和DTM(desire targeted mutation)策略,突变杂交种中单88的母本CX1的叶夹角形成关键基因ZmLG1,获得株型紧凑的改良母本自交系CX1-lg1。以此母本与中单88的父本CX2杂交,配制获得株型紧凑的ZmLG1Zmlg1改良杂交种中单88M。对改良母本CX1-lg1的制种效率及改良杂交种中单88M在增密栽培下的产量进行评估。结果显示:(1)通过母本株型改良能够实现对杂交种株型的改良;(2)株型紧凑的改良母本CX1-lg1在5 000株/667 m2的条件下有更高的制种效率;(3)改良杂交种中单88M在不同环境和密度下均有更紧凑株型,且在较高栽培密度下实现增产。以上结果表明基因编辑技术能够通过靶向特定基因实现精确的表型调控,借助DTM策略改良亲本可以实现对杂交种特定表型的改良。 展开更多
关键词 基因编辑 紧凑株型 叶夹角 高产
下载PDF
Approximation by Complex Baskakov-Szsz-Durrmeyer Operators in Compact Disks
20
作者 Sorin G.Gal Vijay Gupta 《Analysis in Theory and Applications》 CSCD 2015年第2期207-220,共14页
In this paper, we deal with the complex Baskakov-Szasz-Durrmeyer mixed operators and study Voronovskaja type results with quantitative estimates for these operators attached to analytic functions of exponential growth... In this paper, we deal with the complex Baskakov-Szasz-Durrmeyer mixed operators and study Voronovskaja type results with quantitative estimates for these operators attached to analytic functions of exponential growth in DR = {z ∈ C; |z| 〈 R}. Also, the exact order of approximation is found. The method used allows to construct complex Szasz-type and Baskakov-type approximation operators without involving the values on [0,∞). 展开更多
关键词 Complex Baskakov-Szzsz-Durrmeyer operators Voronovskaja type result exact or-der of approximation in compact disks simultaneous approximation.
下载PDF
上一页 1 2 22 下一页 到第
使用帮助 返回顶部