构造二重积分解决定积分问题

定积分不等式的证明方法多种多样。一般常规的方法有：研究被积函数在给定区间上的单调性、凸性、最值等。本将给出一种方法，即利用变量替换手段将定积分转化为二重积分，再去证明。     

Mechanisms of acute intestine injury by γ-ray irradiaton and its therapy

BALB/c mice and human intestinal epithelial cells were irradiated to different doses by ^60Co γ-rays. They were sampled for chromosome pattern analysis, intestinal morphology, and a number of other biomedical tests to investigate mechanisms of acute intestine injury by γ-ray irradiation and its effective treatment methods. The resuits indicated that:     

IBM M Pro 6225工作站·VS·普通PC

引子 随着普通PC的性能越来越高,成本越来越低,部分专业用户在考虑用普通的高端PC替换原有的工作站产品,运行专业的图形图像程序(CAD/CAM,DCC),以使降低购买成本.本刊评测室进行了一次普通PC和IBM MPro 6225中档工作站的评测,以验证这种做法是否具有足够的合理性.     

顽固文件 请你出局

“删除文件或文件夹时出错:无法删除××:访问被拒绝。请确定磁盘未满或未被写保护,而且文件未被使用。”在删除某一文件(夹)时面对这样的信息,不管是对于老鸟还是菜鸟都是一件头痛的事,可偏偏这种事还时有发生。不过自从有了CopyLock——     

Reg Organizer史上最强之注册表工具

因为Windows自带的注册表编辑功能太弱．因此第三方的注册表编辑器工具非常多。在这些工具中，功能最强大的当数Reg Organizer．它不仅具备强大的注册表编辑修改功能，而且还具备ini文件编辑、注册表清理以及强大的注册表数据搜索替换功能，是注册表“玩”家必备的超级工具。     

图标，我用自己的

有文件就有图标。图标好比人的一件外衣，体现了穿着者的个性。衣服的来源有两种一种是购买成品．另一种是定制。电脑圈标也是一样。一种是从网上直接下载图标文件．将原有图标替换掉。另一种是利用特定的图标编辑软件自己制作．彻底DIY．彻底个性化。本期．我们将为大家介绍如何DIY个性图标．让美丽的图标在装扮屏幕的同时也装扮出你的好心情!     

3·15探寻网页清洁市场

本文可以学到1网页文字水印、干扰码的由来2如何清除水印及干扰码本文相关小知识网页干扰码的由来由于目前我国对于知识产投的保护尚不健全,尤其在网络媒体这一块,很多辛苦写出来的原创文章都轻易地被人窃取。所以,厚创者们就想到了在网页中加上文字水印,干扰码的方法来防止自己的文章     

Preparation and Characterization of Fe3O4 Magnetic Nano-particles by 60Co γ-ray Irradiation

By using a new method, 60C0 γ-ray irradiation, Fe3O4 magnetic nano-particles were successfully synthesized at room temperature under ambient pressure. The structure, morphology and magnetic properties of these nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM), respectively. The radiation formation mechanism was also discussed. The results show that the absorbed dose can greatly influence the structure, morphology and magnetic properties of the products. XRD and TEM studies show that the product prepared by γ-ray irradiation (10 kGy) is pure FesO4 phase and the mean diameter of these nano-particles is about 21 nm. The Fe3O4 nano-particles synthesized by γ-ray irradiation (10 kGy) are mainly in small cubic shape and the size uniformity of these particles is good.     

Co掺杂对Nb95W5二元固溶体合金结构和氢渗透性能的影响

合金化是克服第五副族金属(Nb,V,Ta)氢脆问题的有效方法.以Nb-5W为基础成分,探索第三组元(Co)掺杂(X=1,2,3,5)对Nb95-xW5Cox合金结构和氢渗透性能的影响规律.研究证实:制备的Nb95-x-W5Cox样品为Nb-bcc固溶体合金,随着Co掺杂量增加,其晶胞畸变收缩明显,形成贫Co基体区和以N...