(电子管用)铈钍吸气剂(商品名)

But most significant of all, the jaguar has a tell-tale trademark. Instead of going for the neck or snout like most cats do, it kills with a crushing bite through the skull into the brain. This makes the jaguar prime suspect in this case. Even the gl

发表于:2018-12-03 / 阅读(167) / 评论(0) 分类 探索与发现2012年

These holes are the unmistakable hallmark of a violent death. Their shape suggest they were made by the teeth of a big cat, but which one? Today theres only one large cat in the region, the Florida panther. Though similar to the cougar at the western

发表于:2018-12-03 / 阅读(186) / 评论(0) 分类 探索与发现2012年

But how did one man and a spear produce the huge force behind this blow? The answer lies with small bits of ivory like this. They were once part of an atlatl, or spear thrower. An atlatl acts as a sort of catapult, magnifying the strength of a hunter

发表于:2018-12-03 / 阅读(181) / 评论(0) 分类 探索与发现2012年

At first sight, manatees might look like seals or dolphins. But in fact, some of their closest relatives live on land. These toenails are the giveaway, remarkably similar to those of elephants. 13,000 years ago, two other members of the elephant fami

发表于:2018-12-03 / 阅读(211) / 评论(0) 分类 探索与发现2012年

By piecing together the evidence these creatures left behind, we can build a picture of this sub-tropical corner of the continent as it was 13,000 years ago. While most of North America was still in the grip of the Big Freeze, Florida was an ice age

发表于:2018-12-03 / 阅读(191) / 评论(0) 分类 探索与发现2012年

This is Florida, a taste of the tropical, one of the world's most popular holiday destinations. Here mankind's unquenchable desire to explore and colonise reaches astronomical proportions. Eight, seven, six, five, four, three, two, one. Ignition. Lif

发表于:2018-12-03 / 阅读(199) / 评论(0) 分类 探索与发现2012年

This creates steam in oasis and a profusion of life. Today, these warm springs are a refuge for one of Florida's most tropical inhabitants. The West Indian Manatee wasn't present during the last ice age, but returned here as the waters warmed up. Eve

发表于:2018-12-03 / 阅读(175) / 评论(0) 分类 探索与发现2012年

But the glyptodont wasn't a reptile. So what was it? There is a relative of the glyptodont thats still alive today. It's the armadillo and it's a mammal, the only mammal with this kind of armor in the whole of North America. It may give us some idea

发表于:2018-12-03 / 阅读(193) / 评论(0) 分类 探索与发现2012年

Online Classes May Force Changes at Universities This is pretty amazing, said the University of Virginia's David Evans, teaching an online introduction to Computer Science. Online classes are now taught by many top universities and offer everything f

发表于:2018-12-16 / 阅读(193) / 评论(0) 分类 VOA标准英语2013年(六月)

This triggered other dramatic changes. As sea levels dropped, so did the inland water tables. Florida's fresh water drained away through the porous limestone rock. Pools dried up and springs diminished. Florida was on the brink of drought. And animal

发表于:2018-12-27 / 阅读(243) / 评论(0) 分类 探索与发现2013年

Could it be that drastic water shortage was the reason for the mastodons' epic migrations? Another big piece of this puzzle lies far out to sea. This is the ocean floor. But this isn't rock sprouting out at the bottom. It's wood. It's the remains of

发表于:2018-12-27 / 阅读(153) / 评论(0) 分类 探索与发现2013年

But despite their name, the mighty Everglades did not exist during the ice age. So what did pre-historic Florida look like? There is one place in northern Florida that has revealed more ice age secrets than almost anywhere else, the dark slow-moving

发表于:2018-12-27 / 阅读(146) / 评论(0) 分类 探索与发现2013年

The cold climate conifer forests of the north displaced broadleaved woodlands. Plants and animals were gradually pushed south to find a warmer climate. Florida became a refuge from the cold. Down here is where the Ice Age north met the subtropical so

发表于:2018-12-27 / 阅读(163) / 评论(0) 分类 探索与发现2013年

By Dan Robinson Capitol Hill 18 May 2006 U.S. officials say implementing the Darfur peace agreement requires sustained international attention to Sudan in coming months. A congressional hearing examin

发表于:2019-01-07 / 阅读(250) / 评论(0) 分类 2006年VOA标准英语(五月)

By Alan Silverman Hollywood 02 April 2006 It's back to prehistoric times for a sequel to the 2002 computer-animated family film that featured a grumpy mammoth and his traveling companions: a quick-wit

发表于:2019-01-08 / 阅读(232) / 评论(0) 分类 2006年VOA标准英语(四月)

Ocean Floor Reveals Past Climate Changes Time capsule Lamont research professor Maureen Raymo, the director of the Core Repository, slides open a long, narrow drawer from the cabinet. Like thousands of others here, the drawer contains a long, thin cy

发表于:2019-01-13 / 阅读(215) / 评论(0) 分类 VOA标准英语2012年(一月)

Supernatural Romance, Action Attract All Ages In the Houston suburb of Tomball, these women get together frequently to socialize and chat about the books they are reading. Cathy Clark says many of those books - targeted at teens - also attract adult

发表于:2019-01-13 / 阅读(199) / 评论(0) 分类 VOA标准英语2012年(三月)

The Science of Climate Change Climate negotiators are meeting in Durban, South Africa beginning from November 28-December 9 to discuss the planet's changing climate. The first decade of this century was the hottest on record. Polar ice is melting. Gl

发表于:2019-01-13 / 阅读(180) / 评论(0) 分类 VOA标准英语2011年(十一月)

Though very powerful, shes not a sprinter and she needs to get close to her prey before she strikes. This time shes run too soon and its a fruitless chase. Then her attention is diverted to a slower-moving target, slow but not defenseless. She backs

发表于:2019-01-23 / 阅读(191) / 评论(0) 分类 探索与发现2013年

SCIENCE IN THE NEWS - November 12, 2002: Oldest Evidence of Jesus? / Mapping Genes that Cause Disease / 2002 World Health Report VOICE ONE: This is Steve Ember. VOICE TWO: And this is Bob Doughty with

发表于:2019-01-30 / 阅读(258) / 评论(0) 分类 科技之光
学英语单词
AACPR
actual price
address compare control
Allium korolkowii
Annaba, G.d'
anthelmintic treatment
bag-and-baggage policy
Baghwana
blade-lattice
Bol'shaya Sarovka
bosque
caenozoic
californium ion
cancellous
cardiomyopathy
cast a horoscope
cenesthesia
clearspans
clypofrons
coal-drop
commercial radio
conditionally exempt
containerful
crispy critters
cristate
cross-path current
cylindrical open-ended crucible
de palma
delexicalizes
direct current resistor
dissipation energy
document composition system
double-reheat stream tubrine
econnoisseur
electric power station near coal mines
enframement
ethertalks
get into
henology
high frequency conditioning
Hjortφ
Ilyocyprimorpha
impressionabilities
incarnification
intellectual power
inter-lineation
Japanese fir
Japanese law
Justicia hainanensis
light flux
linear voltage displacement transducer
manhole collar
market-out clause
marsas
material requisition unit
membrane method of water proofing
mission-oriented audit
monetary and credit crisis
muffle oneself up well
multiple cropping
normalized floating control
oil unloading pump house
optical homogeneity
pakila
pantopororate
parabolic group delay
partial ossicular replacement prosthesis
periventricular fiber
phenamine
PINGUIPEDIDAE
plumed tussocks
preliminary merchandise
puerperal metritis
pulling something off
random material
scented fern
shaded pole motor
shake-out grid
shaker conveyor
ship lock
social marketing
solution scouring
spectralist
spotting ore
steinlen
stigmatocythere flora
stomatological
subfamily Emberizidae
superfusions
tea-cloths
TF1
thymic veins
tour rep
transmission loss of leaky coaxial cable
Trzcianka
ultrasonic vibration dyeing
unattended time
Valthjófsstadhur
water level regulator
work at low pressure
yapa