埃里卡的故事小时候,我很害羞,这令我很痛苦。我的意思是,别人跟我说话时我甚至不敢正视对方。因此,妈妈非常希望我通过某种活动来克服胆怯。就在这个时候,我们住的那条街上
Conventional methods of plant breeding and agronomic practices remained a successful tool to maintain the pace of food production for centuries but due to chang
0、前言随着科学技术的飞速发展、市场的激烈竞争、社会要求的多样化、保护人类生存的环境及充分利用自然资源的需要,建立一种理想的生产系统(生产模式)已成为世界各国非常重
<建设项目经济评价方法与参数>(简称方法与参数)发表于1987年,在我国从计划经济向市场经济过渡时期,<方法与参数>的确起了很大的作用,特别是对各级政府的立项和项目审批.但是
An efficient protocol for high frequency in vitro regeneration of Meizotropis pellita an endangered and endemic plant was developed. In vitro germination of the
混凝土自干燥收缩与其内部相对湿度的下降密切相关。低水胶比混凝土在结构形成以后的初始阶段存在较大的自干燥收缩,但通常此时混凝土内部相对湿度较高,采用传统的湿度计难以
Generally forest fires are related to human activities and need an effective fire prevention and suppression organization, based on a deep knowledge of the terr
High-mountain forests (>3500 masl) are the main supplier of environmental services to Mexico City and its metropolitan area. Taking as a study case the Nevado d
在社会分工日趋细化的时代,传统而封闭的大而全、小而全的生产模式越来越缺乏竞争力.众多的各具优势的企业为强化自身竞争能力而联合起来,相互补充,互相支持,使每个企业都能
In the Central Desert of northern Baja California, blue fan palm populations (Brahea armata) are found as isolated oases on mountaintops and along canyons with