c**i
发帖数: 6973 | 1 You say, "你跟本不用查找专业文献，反渗透膜是porous 的高分子材料，有点高分子
物理知识的人都知道温度降低，高分子链的热物理性能和构型会发生改变，这样膜的孔
径就会收缩，透水率就会明显降低."
In the primary school, we learn that if we heat a metal with a hole, the
hole will be bigger. Search the Web, with the terms (metal hole heat).
What is used in reverse osmosis (RO) is not metal but polymer. Thus there is
nothing intuitive about how pore will behaves. Indeed emperically there are
two types of pores in a RO membrane.
(1) That temperature affects membrane permeability is a fact. ... 阅读全帖 |
|
N******p
发帖数: 2777 | 2 说了半天，你这还是靠一张十米靶的图直接放大缩小弄出来的阿。不够好了，我下面这
个Matlab script可以计算不同距离下的各环大小（弹径影响已经考虑进去了）。
至于气步枪靶，如果考虑到弹径影响的话，在七米远十环不是一个点，而是 -1.5mm，
这种情况下十环是打印不出来的，只有用outward scoring gauge才能看是不是打中十
环了。
% Projectile radius (mm)
r = 4.5/2;
% Full-size target score ring radii (mm)
R = [5 11.5 27.5 43.5 59.5 75.5 91.5 107.5 123.5 139.5 155.5]'/2;
% Full-zie bullseye radius
BE = 59.5/2;
% Full-size distance (m)
D = 10;
% Reduced distance (m)
Dx = 7;
% Reduced target score ring radii (mm)
Rx = (Dx/D*(r+R) - r);
% Reduced bu |
|
T**********e
发帖数: 29576 | 3
你这简直太多概念混乱.
decay指不稳定同位素衰变为稳定同位素.
TI的毒性是化学性细胞毒性,和同位素如何衰变没关系.
任何毒物都会有个体内代谢速度,但是会在头发指甲沉集,这部分不会随时间改变因而成
为法医检定的重要依据.
Part of the reason for thallium's high toxicity is that, when present in
aqueous solution as the univalent thallium(I) ion (Tl+), it exhibits some
similarities with essential alkali metal cations, particularly potassium (
due to similar atomic radii). It can thus enter the body via potassium
uptake pathways.[3] Other aspects of thallium's chemistry differ strongly
from that of the al... 阅读全帖 |
|
B******1
发帖数: 9094 | 4 大小圆与切线共直线的错误：循环论证：
就是，先假设我们能做出这个图形，那么，小圆与大圆相切，那么三点共直线。
同时，三点共直线也可以证明小圆和大圆相切。
Wrong. The key here is not the three points are on the same line, but the distance between the two centers equals the difference between the two radii.
You still did not get it. |
|
|
T**7
发帖数: 264 | 6 杂志介绍
http://www.rsc.org/publishing/journals/MB/about.asp
Impact factor: 3.859
劳驾站内信发给我：
你的名字，你的email，你的专业特长关键词（3－5个即可），你的发表文章。
为了你省事，你可以copy paste你的resume也可以
希望不同专业都来试试，“分子生物系统”杂志算是交叉学科杂志。
谢谢！
稿件摘要：
TITLE: Noninvasive measurement of respiratory activity of mouse embryoid
bodies and its correlation with undifferentiation/differentiation markers
ABSTRACT: Mouse embryoid bodies (mEBs) were evaluated in detail on the basis
of respiratory activity and high-throughput quantitative reverse
transcriptio... 阅读全帖 |
|
N******p
发帖数: 2777 | 7 Eh. Even if you can get a 2m sight radius on a pistol, the wobble of a
pistol is still going to be much greater than rifle. 50m pistol (free pistol
) event, which has no limit on the sight radius, thus allowing pistols with
very long barrels and sight radii, is considered to be the most challenging
discipline by pistol shooters. |
|
f****l
发帖数: 5514 | 8 谢谢。能翻译一下那个表里的7个项目么……
貌似我看了点视频至少知道有mogul, 没有旗门的大回转，还有没有旗门的不同大小
turn radii都用上的一个，其他的就不清楚了 |
|
p******u
发帖数: 30 | 9 发信人: YYalone (简单就是幸福), 信区: IQDoor
标 题: 100个著名初等数学问题 （41－60）
发信站: 两全其美网 (Fri May 25 15:52:56 2007), 本站(lqqm.net)
第41题 阿尔哈森弹子问题Alhazen's Billiard Problem 在一个已知圆内，作出一
个其两腰
通过圆内两个已知点的等腰三角形.
第42题 由共轭半径作椭圆An Ellipse from Conjugate Radii 已知两个共轭半
径的大
小和位置，作椭圆.
第43题 在平行四边形内作椭圆An Ellipse in a Parallelogram, 在规定的平
行四边形
内作一内切椭圆，它与该平行四边形切于一边界点.
第44题 由四条切线作抛物线A Parabola from Four Tangents 已知抛物线的四
条切线
，作抛物线.
第45题 由四点作抛物线A Parabola from Four Points. 过四个已知点作抛物
线.
第46题 由四点作双曲线A Hyperbola from Four Points. 已知直角（等 |
|
H********g
发帖数: 43926 | 10 标题误导了（我一开始理解错了这个图，以为是从河系顶上往下看）。
这套图的原意是演示黑洞对光的弯曲效果，意思是说一个人如果正在掉进黑洞，看到的
景象是啥。河系在这里就是个背景图，还是从我们的方向侧着看的。
这个黑洞是一个假想的，十倍太阳质量黑洞，不是河系中间那个（河系中间那个估计有
410万个太阳质量），也不是从河系顶上往下看。。
这是原图的网页：
http://www.spacetimetravel.org/expeditionsl/expeditionsl.html
上面的图是在20个Schwarzschild radii处的效果。一个Schwarzschild radius （rs）
就是某个质量成为黑洞的极限最大半径。
一个太阳质量的rs是2.95千米。rs和质量成正比(rs=2Gm/C^2)，所以10个太阳质量的rs
就是29.5km。20个rs处就是大概600km。 |
|
w****p
发帖数: 6 | 11 比较两个教授的publication，大家觉得哪个好？
#######################################
教授A
Selected Publications:
1. Xin M. Liang, Weiping Ding, et al., Microfabricated thermal conductivity
sensor: a high resolution tool for quantitative thermal property measurement
of biomaterials and solutions, Biomed Microdevices, (2011)13: 923–928. (
SCI&EI, IF:3.386, JCR:2区)
2. XM Zhou, ZQ Shu, WP Ding, et al., Heat transfer analysis for the design
and application of the passive cooling rate controlled device-Box-in-box,
Int ... 阅读全帖 |
|
f***l
发帖数: 1157 | 12 这个杂志早些年还真发了些高引的论文，估计多是方法学的东西。
导致今年飙升的应该是最后这篇08年的Review，引了6,572 次
1. Title: REVISED EFFECTIVE IONIC-RADII AND SYSTEMATIC STUDIES OF INTERATOM
IC DISTANCES IN HALIDES AND CHALCOGENIDES
Author(s): SHANNON RD
Source: ACTA CRYSTALLOGRAPHICA SECTION A Volume: 32 Issue: SEP1 Pages:
751-767 Published: 1976
Times Cited: 20,480
2. Title: PHASE ANNEALING IN SHELX-90 - DIRECT METHODS FOR LARGER STRUCTUR
ES
Author(s): SHELDRICK GM
Source: ACTA CRYSTALLOGRAPHICA SECTION A Volume: 46 Pages: 467 |
|
e******g
发帖数: 29 | 13 不对
首先，这个问题跟你用不用DFT无关，即便用HF或post-HF这个问题的表现也是一样
的。
其次，siesta的具体实现里面是没有planwave的。
然后，siesta的计算精度不仅仅是由basis orbital的cutoff radii和数目确定
的，其他的参数也对精度有影响，包括realspace grid density
radius
grid 的参 |
|
s********n
发帖数: 235 | 14 1.Title: REVISED EFFECTIVE IONIC-RADII AND SYSTEMATIC STUDIES OF INTERATOMIC
DISTANCES IN HALIDES AND CHALCOGENIDES
Author(s): SHANNON, RD
Source: ACTA CRYSTALLOGRAPHICA SECTION A Volume: 32 Issue: SEP1 Pages:
751-767 DOI: 10.1107/S0567739476001551 Published: 1976
http://journals.iucr.org/a/issues/1976/05/00/a12967/a12967.pdf
2.Title: EMPIRICAL BOND-STRENGTH BOND-LENGTH CURVES FOR OXIDES
Author(s): BROWN, ID; SHANNON, RD
Source: ACTA CRYSTALLOGRAPHICA SECTION A Volume: A 29 Issue: MA... 阅读全帖 |
|
s*****g
发帖数: 352 | 15
Pick any two points on a circle, and you get a secant line.
Draw a straight line perpendicular to this secant line, and
it goes through the center of the circle. Now pick two other
points and repeat the above two steps. Where the two perpendicular
lines cross is the center of the circle. From that you'll know
the radius, etc etc.
Another way is to assume a center (x,y,z) and pick 5 or 6 points
on the curve, hence you get 5 or 6 radii. And your goal, for curve
fitting, is to minimize the differe |
|
h*****y
发帖数: 366 | 16 我想问下回旋半径,radius of gyration是指的是什么.
我在wiki上面查了下,In polymer physics, the radius of gyration is used to
describe the dimensions of a polymer chain.
然后有一个公式,其中有个Rk,还有个Rmean.我想象不出它们具体指得是什么.
我看的一本书上说,polymers are most extensively solvated in solvents of the
same delta value,resulting in stiffer chains with greater radii of gyration.
究竟是怎么一回事呢?
溶剂化以后为什么会变硬,直?回旋半径为何会变大?
我不是学高分子得,但是修得一门课涉及到了这个概念.很让我苦恼.
谢谢解答.小女子将不胜感激. |
|
c****e
发帖数: 2097 | 17 you need the local radii of curvature in terms of z. |
|
a****e
发帖数: 1247 | 18 In geometry, Euler's theorem, named after Leonhard Euler, states that the
distance d between the circumcentre and incentre of a triangle can be
expressed as
d^2=R(R-2r)
where R and r denote the circumradius and inradius respectively (the radii
of the above two circles).
From the theorem follows the Euler inequality:
http://en.wikipedia.org/wiki/Euler's_theorem_in_geometry |
|
p*****k
发帖数: 318 | 19 not sure what exactly DuGu had in mind, but im guessing that
he wants the radii of these circles nonzero and bounded.
otherwise, e.g., the infinite str8 line R could be considered
as a circle with infinite radius:
(x-R)^2+y^2=R^2 with R->infty |
|
J**********g
发帖数: 213 | 20 This part is straightforward too, but the black circles in the following
link actually intersect at more than two points with orange cirles (or
sphere) with certain radii. This is true because the radius of sphere has to
be taken in a continous way to cover "most part" of R^3, so actually they
are not disjoint at all....
http://www.cut-the-knot.org/proofs/tessellation.shtml#solution
are |
|
D**u
发帖数: 204 | 21 Each orange sphere (centered at the origin) intersects with exactly 2 points
from all the black circles. So I don't know why you claim that "but the
black circles in the following link actually intersect at more than two
points with orange sphere with certain radii."
Also, "disjoint" simply means "no intersection", and does not mean "not
continuous". Is this part of the ambiguity that caused the confusion?
to |
|
D**u
发帖数: 204 | 22 Sorry that the link I gave might bring more confusions than it clears up for
you. The picture might be confusing in the sense that they draw it in black
and orange circles, but indeed they are
black circles (not sphere) and orange spheres (not circles, with all radii 0
Also the black circles are NOT drawn after picking some points on the orange
spheres. The black ones and oranges are drawn independently.
though
is
,
something |
|
w******h
发帖数: 115 | 23 【 以下文字转载自 Joke 讨论区 】
发信人: windsigh (本少爷), 信区: Joke
标 题: 做题了做题了
发信站: BBS 未名空间站 (Tue Sep 18 11:21:40 2007), 转信
求水分子的体积？
info: van de walls radii for O 1.29A, for H 1.16A, H bond length 2.76A
只给了这些条件，最后给的答案是13.81A^3，空间利用率~45%
水分子的结构 O...H
/
H
假设全部都形成氢键 O--H...O
请给出计算公式。 |
|
S********f
发帖数: 36 | 24 Spherical surface samples are measured for their radii (R) and imaged by a
camera. The image is not a numerical value, but m different quantities (Q1,
Q2,..., Qm) are derived from it using different models. Now if I want to
analyze the correlation between R and each Qi (i = 1,..., m), should
Bonferroni correction be applied to adjust the significance level? Thanks! |
|
