In order to meet the high temperature environment requirement of deep and superdeep well exploitation, a technology of large length-to-diameter ratio metal stat
国际、国内市场双向需求结构下的近代中国农业商品化呈现出有所发展,但又很不发达的基本状况。其中最主要的因素是国际市场需求在推动近代中国农业商品化畸形发展,因而成为其
信阳市平桥区是农业大区，耕地面积8.8万hm2，其中水稻面积3.73万hm2，小麦面积3.67万hm2，油菜面积1.07万hm2，玉米面积0.8万hm2，花生面积2万hm2，蔬菜面积0.8万hm2，连续多年被农业部确定
In order to promote the tolerance and controllability of the multi-degree-of-freedom(M-DOF) ultrasonic motor, a novel two-degree-of-freedom(2-DOF) spherical ult
春光区块近年来逐渐发现了一系列绝对电阻率低值油藏,其电阻率一般为1~3Ω·m。研究认为其受沉积背景、构造成藏等宏观上的控制,结合成岩作用下储层自身的微观岩石物理机
To realize numerical simulation of rolling and obtain the hot forming process parameters for X70 HD steel, the flow stress behaviors of X70 HD steel were invest
辽河滩海西部凹陷沙一、二段对应一个完整的三级层序，可划分为3个体系域5个准层序组，各准层序组全区地震可识别追踪，砂体展布规律受基准面旋回控制，低位期砂体沉积具有“填平补齐
Li Fe PO4/C was prepared via solid state reaction and characterized with X-ray powder diffraction and charge–discharge test. As-prepared Li Fe PO4/C has a trip
In order to consider the influence of steel pole on the measurement of wind speed sensors and determinate the installation position of wind speed sensors, the f
土壤板结是指土壤表层缺乏有机质,结构不良,在灌水或降雨等外因作用下土壤结构破坏、土料分散,土壤干燥后受内聚力作用使土壤变硬。一、形成土壤板结的原因(一)农田土壤质地太黏,耕作层浅黏土中的黏粒含量较多,加之耕作层平均不到500px,土壤中毛细管空隙较少,通气、透水、增温性较差,下雨或灌水以后,容易堵塞空隙,造成土壤表层结皮。(二)有机肥严重不足,秸秆还田量减少土壤中有机物质补充不足,就会使土壤有机质