[有机化学] 白叶藤生物碱

A hundred years ago, there are one and a half billion people on earth. Now, over six billion crowd our fragile planet. But even so, there are still places barely touched by humanity. This series will take you to the last wildernesses and show you the

发表于:2018-12-03 / 阅读(133) / 评论(0) 分类 探索与发现2012年

by Jason Marshall Would you believe its possible to send someone a secret message secured with absolutely unbreakable encryption using only a bit of simple arithmetic? Well, it isthe solution is surprisingly simple and was used by British, German, an

发表于:2018-12-07 / 阅读(117) / 评论(0) 分类 数学英语

The penguins stay when all other creatures have fled because each guards a treasurea single egg rested on the top of its feet and kept warm beneath the downy bulge of its stomach. There is no food and no water for them. And they will not see the sun

发表于:2018-12-27 / 阅读(137) / 评论(0) 分类 探索与发现2012年

SCIENCE REPORT – February 20, 2002: Pine Island Glacier By Jerilyn Watson This is the VOA Special English Science Report. Scientists have expressed much interest in the development of a huge new ice

发表于:2019-01-02 / 阅读(170) / 评论(0) 分类 科技之光

Anchor: Dan Brown's best-selling novel The Da Vinci Code is second only to the Harry Potter series as the best-selling novel of all time. And it has inspired a whole slew of books on Biblical puzzles, Opus Dei, and the life of Mary Magdalene, as wel

发表于:2019-01-08 / 阅读(283) / 评论(0) 分类 2006年NPR美国国家公共电台

1. President Bush is asking Congress for money for another troop surge. He wants to send more than 8,000 more troops to Iraq and Afghanistan. The request comes as Congress is trying to figure out ways to get the U.S. out of Iraq. 2. Meanwhile, repre

发表于:2019-01-08 / 阅读(185) / 评论(0) 分类 美联社新闻一分钟2007

They are constantly on the move. New-born calves have to be up and running the day they are born. But the vast herds do not travel alone. Wolves. Packs of them, eight to ten strong, shadow the migration. And they are hungry. Its the newly born calves

发表于:2019-01-23 / 阅读(157) / 评论(0) 分类 探索与发现2012年

But they are hungry and eager to reach their mother whos delayed feeding them on this special day. Now she lures them with the promise of milk, the only food the cubs have known since they were born, deaf and blind beneath the snow some two months ag

发表于:2019-01-23 / 阅读(155) / 评论(0) 分类 探索与发现2012年

Day 10. And the mother has let her cubs a mile from the den. Its time to put them to the test. Theyve grown enormously in confidence, but they dont have their mothers sense of urgency. At last it seems that they are ready for their journey. And they

发表于:2019-01-23 / 阅读(139) / 评论(0) 分类 探索与发现2012年

Midsummer on the tundra and the sun does not set. At these altitudes, the suns rays are glancing and not enough of their energy reaches the ground to enable trees to grow. Youll need to travel five hundred miles south from here before that is possibl

发表于:2019-01-23 / 阅读(135) / 评论(0) 分类 探索与发现2012年

As we travel south, so the suns influence grows stronger. And at 50 degrees of latitude, a radical transformation begins. Summers here are long enough for broadleaf trees to replace conifers. Broadleaves are easier to eat and digest, so now animals c

发表于:2019-01-23 / 阅读(154) / 评论(0) 分类 探索与发现2012年

The advance of the seasons brings constant change. As the suns influence diminishes in the north, so the deciduous forests of America begin to shut down, losing their leaves in preparation for the dark, cold months ahead. One season hands over to ano

发表于:2019-01-23 / 阅读(141) / 评论(0) 分类 探索与发现2012年

The character of the forest changes as we descend, becoming ever darker and damper, favoring different kinds of animals and plants. Less than two percent of the sunlight reaches the floor. But even here there is extraordinary variety. In the Great Is

发表于:2019-01-23 / 阅读(128) / 评论(0) 分类 探索与发现2012年

The sun beating down on tropical waters powers the weather systems of the globe. Moisture evaporates from the warming ocean and rises to create great storms. The winds generated out at sea sweep inland across the continents. As they travel across the

发表于:2019-01-23 / 阅读(145) / 评论(0) 分类 探索与发现2012年

Deer are frequent casulties of the harsh winter. And these leopards are not above scavenging from a corpse. African leopards could never survive here. But the Russian cats have thick fur to shied them from the cold. There are only 40 Amur leopards le

发表于:2019-01-23 / 阅读(167) / 评论(0) 分类 探索与发现2012年

Their secret is teamwork. Impala are their favourite prey. They start to hunt and the pack splits up. An aerial viewpoint gives a new insight into their strategy. As the dogs approach their prey, they peel off to take up separate positions around the

发表于:2019-01-23 / 阅读(140) / 评论(0) 分类 探索与发现2012年

The dogs know their prey must come out or drown. Now its a waiting game. The rest of the pack are calling. Theyve made a kill in the forest and this is an invitation to join in the meal. The impala is in luck. A pack this size kills once a day and ev

发表于:2019-01-23 / 阅读(148) / 评论(0) 分类 探索与发现2012年

All across southern Africa, all animals are journeying for the same reason. Buffalo join the great track. Nowhere else on Earth are so many animals on the move for the same urgent purpose. They are all heading for the swamps of the Okavango, a vast i

发表于:2019-01-23 / 阅读(158) / 评论(0) 分类 探索与发现2012年

At the peak of the dry season in the Kalahari, water arrives in the Okavango. It fell as rain a thousand miles away in the highlands of Angola and has taken nearly five months to reach here. The water drives out insects from the parched ground which

发表于:2019-01-23 / 阅读(131) / 评论(0) 分类 探索与发现2012年

By Jill Moss THIS IS AMERICA – April 15, 2002: Visiting the Capitol VOICE ONE: Historians have described the United States Capitol building as “the most recognized sign of democratic government in

发表于:2019-01-30 / 阅读(234) / 评论(0) 分类 This is America
学英语单词
acetylspermine
ambiguity of the main facts
amycil
anaiss
antiphlogosis
basicaryoplastin
benzalkonium
birdfeeders
black and white infrared image
blackened (wire) gauge
blisteringly
bridgefoot
bubble gage
cantilever conveyer
caulking set
cayton
change-managements
cockcroft-walton's apparatus
Collins Park
commander
common emitter amplifier
coolant make up
corequisites
cylindrocarpine
deceitful
desert zone
developmental epoch
digital projector
digs in
Dubh Sgeir
edge of rim
empyema of gall-bladder
equalizing compartment
esber
eunuch(s)
Euonymus ficoides
everr
fee-tail
flash labeling
forgettest
foryears
fuel pump case
governor drive pinion
grub hook
Guemar
hereaways
hybridizers
hydraulic mining operation
ill-judging
in-service education of teachers (inset)
interceptive orthodontics
inventory decisions
ionization pulse
isopropyl hydrocupreine
Issaouane
kasavin
labichorea
LDMI
lift a weight off someone's mind
lilyturf
longwall mining to the dip or to the rise
minute particulars
miscellaneous cases
model cam
modulus at a definite elongation
mucohemorrhagic
nesslerization
Nihau
nonhyperlinked
nonprice predaction
oceanity
octaxon
operational parameters
overall brightness transfer charac-teristic
Pambrun
partnership characteristics
party loyalty
pickled with grains
possible rate
prozzies
quileute
rapid sintering
rearward overturning
Retinaculum musculorum extensorum inferius
savanah
sensitized cathode
setting stake
sigma amplifier
single policy
slapdash
snoopier
Station WRC is off the air now
structural breakdown
subproteomics
subseguently
Syklandol
synpsylla wendlandiae
terrorized
tissue repair
virus encephalomyelitis of swine
whighen
yorkstones