【摘 要】
：
近年来,世界农业机械化事业由于农业問題受到人們的重视,比第二次世界大战以前有很大发展。拖拉机的結构和性能显著改善,各种耕作栽培机具的技术經济指标大大提高,农业生产
论文部分内容阅读
近年来,世界农业机械化事业由于农业問題受到人們的重视,比第二次世界大战以前有很大发展。拖拉机的結构和性能显著改善,各种耕作栽培机具的技术經济指标大大提高,农业生产机械化工艺过程的研究开展起来,农业机械基本理論的研究更加系統
In recent years, the cause of world agricultural mechanization has been given due attention to by agriculture and has greatly developed before World War II. The structure and performance of the tractor significantly improved, the technical and economic indicators of various farming and cultivating equipment greatly improved, the mechanization of agricultural production process research carried out, the basic theory of agricultural machinery more systematic
其他文献
请下载后查看，本文暂不支持在线获取查看简介。
Please download to view, this article does not support online access to view profile.
曾经的国内前三大视频网站之一的我乐网关停,已经砸入我乐网的3000万美元要想“解套”是何其之难。视频牌照的政策暗礁浮出了水面,也使资本陷入了未知风险的死循环。
Once t
请下载后查看，本文暂不支持在线获取查看简介。
Please download to view, this article does not support online access to view profile.
FRAMIG 2000 is a population-based survey of medical and therapeutic managemen t of migraine in France. A total of 312 migraine sufferers were first identified f
今天一大早,哈维就拉着家里的大山羊出去吃草。在他家附近,有一块边长8米的正方形地,里面长满了绿油油的青草。他刚到草地,托尼也拉着他家的大绵羊过来了。两人一商量,分别把
2月16日晴从前,文具盒里面住着一群好伙伴。一天,它们在讨论,谁的功劳大。铅笔说:“小主人天天用我来画精美的图案,我的功劳大。”尺子说:“小主人划线时要用我才能画出直直
In a recent, hospital-based report, we described a small series of 5 patients with unilateral, more or less chronic, severe forehead pain, that could be tran si
请下载后查看，本文暂不支持在线获取查看简介。
Please download to view, this article does not support online access to view profile.
植物的种子有大有小,形状也各式各样。小的一粒种子只由几十个细胞组成,长度只有几百微米,每粒种子仅重二百万分之一克(象某些兰科植物的种子)。大的,每粒种子竟重达30多斤,
陕北童山濯濯,气候亢旱。土壤为风积黄土,土质为砂质壤土。农民耕地百分之九十系山陵高坡,倾斜由10——60度不等,因之土壤冲刷现象极为严重。加以土地利用之不合理,致土壤结