双语有声读物

Chlorofluorocarbons are also not very abundantthey constitute only about one part per billion of the atmosphere as a wholebut they are extravagantly destructive. One pound of CFCs can capture and annihilate seventy thousand pounds of atmospheric ozon

发表于:2019-02-17 / 阅读(115) / 评论(0) 分类 万物简史

Up to this time, the oldest reliable dates went back no further than the First Dynasty in Egypt from about 3000B.C. No one could confidently say, for instance, when the last ice sheets had retreated or at what time in the past the Cro-Magnon people h

发表于:2019-02-17 / 阅读(118) / 评论(0) 分类 万物简史

Rather than restate every one, scientists decided to keep the inaccurate constant. Thus, Tim Flannery notes, every raw radiocarbon date you read today is given as too young by around 3 percent. The problems didn't quite stop there. It was also quickl

发表于:2019-02-17 / 阅读(141) / 评论(0) 分类 万物简史

Finally, and perhaps a little unexpectedly, readings can be thrown out by seemingly unrelated external factorssuch as the diets of those whose bones are being tested. One recent case involved the long-running debate over whether syphilis originated i

发表于:2019-02-17 / 阅读(144) / 评论(0) 分类 万物简史

Holmes was heroic as much for the obstacles he overcame as for the results he achieved. By the 1920s, when Holmes was in the prime of his career, geology had slipped out of fashionphysics was the new excitement of the ageand had become severely under

发表于:2019-02-17 / 阅读(132) / 评论(0) 分类 万物简史

For seven years, first at the University of Chicago and then at the California Institute of Technology (where he moved in 1952), he worked in a sterile lab, making very precise measurements of the lead/uranium ratios in carefully selected samples of

发表于:2019-02-17 / 阅读(117) / 评论(0) 分类 万物简史

As always, however, nothing was quite as straightforward as such a breezy description makes it sound. Meteorites are not abundant and meteoritic samples not especially easy to get hold of. Moreover, Brown's measurement technique proved finicky in the

发表于:2019-02-17 / 阅读(139) / 评论(0) 分类 万物简史

His main work done, Patterson now turned his attention to the nagging question of all that lead in the atmosphere. He was astounded to find that what little was known about the effects of lead on humans was almost invariably wrong or misleadingand no

发表于:2019-02-17 / 阅读(128) / 评论(0) 分类 万物简史

By counting back through these layers and measuring the amount of lead in each, he could work out global lead concentrations at any time for hundreds, or even thousands, of years. The notion became the foundation of ice core studies, on which much mo

发表于:2019-02-17 / 阅读(173) / 评论(0) 分类 万物简史

Absurdly, he was excluded from a 1971 National Research Council panel appointed to investigate the dangers of atmospheric lead poisoning even though he was by now unquestionably the leading expert on atmospheric lead. 荒唐的是,一个美国研究委

发表于:2019-02-17 / 阅读(141) / 评论(0) 分类 万物简史

On its website, a history of the company makes no mention of leador indeed of Thomas Midgleybut simply refers to the original product as containing a certain combination of chemicals. 在它的网站上,公司的历史没有提及铅──也没有提

发表于:2019-02-17 / 阅读(162) / 评论(0) 分类 万物简史

So who is making it? We arethat is to say, many of our large corporations are still making it at their plants overseas. It will not be banned in Third World countries until 2010. 那么,是谁在生产含氯氟烃?是我们──那就是说,许多

发表于:2019-02-17 / 阅读(149) / 评论(0) 分类 万物简史

It is all, as you can see, just a little unwieldy, but it is the simplest model that can explain all that happens in the world of particles. Most particle physicists feel, as Leon Lederman remarked in a 1985 PBS documentary, that the Standard Model l

发表于:2019-02-17 / 阅读(129) / 评论(0) 分类 万物简史

In an attempt to draw everything together, physicists have come up with something called superstring theory. This postulates that all those little things like quarks and leptons that we had previously thought of as particles are actually stringsvibra

发表于:2019-02-17 / 阅读(117) / 评论(0) 分类 万物简史

String theory has further spawned something called M theory, which incorporates surfaces known as membranesor simply branes to the hipper souls of the world of physics. I'm afraid this is the stop on the knowledge highway where most of us must get of

发表于:2019-02-17 / 阅读(145) / 评论(0) 分类 万物简史

Almost at once the Bogdanov paper excited debate among physicists as to whether it was twaddle, a work of genius, or a hoax. Scientifically, it's clearly more or less complete nonsense, Columbia University physicist Peter Woit told the New York Times

发表于:2019-02-17 / 阅读(127) / 评论(0) 分类 万物简史

Hubble realized that this could be expressed with a simple equation, Ho = v/d (where Ho is the constant, v is the recessional velocity of a flying galaxy, andd its distance away from us). Ho has been known ever since as the Hubble constant and the wh

发表于:2019-02-17 / 阅读(116) / 评论(0) 分类 万物简史

This would mean that the universe was only half the size and age that Sandage believedten billion years. Matters took a further lurch into uncertainty when in 1994 a team from the Carnegie Observatories in California, using measures from the Hubble s

发表于:2019-02-17 / 阅读(102) / 评论(0) 分类 万物简史

The difficulty in making final determinations is that there are often acres of room for interpretation. Imagine standing in a field at night and trying to decide how far away two distant electric lights are. Using fairly straightforward tools of astr

发表于:2019-02-17 / 阅读(109) / 评论(0) 分类 万物简史

The charged pion and antipion decay respectively into a muon plus antineutrino and an antimuon plus neutrino with an average lifetime of 2.603 x 10-8 seconds, the neutral pion decays into two photons with an average lifetime of about 0.8 x 10-16 seco

发表于:2019-02-17 / 阅读(162) / 评论(0) 分类 万物简史
学英语单词
a-whiles
acanthomatous ameloblastoma
adjusting resistance
agrocin
anomaly of specific volume
anvil with an arm
attacing
baggywrinkle
banker's deposits
bottom pinch roll
broidered
bulkheaded
chain lock
checking fixture
cladocarpous
clean lines
colour sth in
control distribution system
countervallations
criticize
cryostase
cyclinder gas
cyclopyrrolones
davita
deiondra
double crop rice
enzymatic tenderizing method
Ericson cycle
ex-official
Exody
flaccid leaf
frame foundation
gallivant around
greyish-bluest
halaelurus burgeri
Halimede
harness races
have a jag on
Helleborus niger
hutmacher
indirect liability
ingenerably
input-output limited system
intervane burner
ion interchange unit
iso code
jaxta-articular adiposis
liped
logical output device
Lonicera japonica Thunb.
low temperatrue brittleness
Malpica
manifold absolute pressure
maximal unipotent subgroup
maximum and minimum tariff
medlocke
meson telescope
mold stripping
monogrammic
napocor
NITD
nontransuranic
orbimage
panormus
penuriously
Petrobia vachushtii
Phytoptus pini
Plactidil
play heck with
podes
praseodymium(iii) selenide
raphe penis
recessus ileocaecalis inferior
reversible magnetizing
rocketpack
rural supply-marketing centre
rushingly
S. B.
saccule (sacculus)
sand roll
secondary trunk road
self-service analytics
semiconductivity
semipallium vexillum
serd
shave sth off sth
signature table
Starling's heart-lung preparation
start-stop button
sterling bond
subacute septicemia
substitute species
sulci hypothalamicus
surface drift
tape laying
threshold extension demodulation
ulectomy
unsaturated fatty oil
violet flower concrete
workolad
yo ho
zubu