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相关概念视频

Southern Blot02:57

Southern Blot

Agarose gel electrophoresis is very useful in separating DNA fragments by size. Running a DNA ladder containing fragments of the known length alongside the sample helps determine the approximate length of the sample DNA fragments. However, additional steps are needed to verify the sequence identity of the sample DNA fragments.
Denatured DNA fragments must be transferred onto a carrier membrane from the gel to make it accessible to a probe - a small ssDNA fragment complementary to the target DNA...
Comparative Excretory Systems02:24

Comparative Excretory Systems

Animals have evolved different strategies for excretion, the removal of waste from the body. Most waste must be dissolved in water to be excreted, so an animal’s excretory strategy directly affects its water balance.
Hyperthermophilic Bacteria01:21

Hyperthermophilic Bacteria

Domain Bacteria includes some unique hyperthermophilic species. They exhibit remarkable adaptations that enable survival in extreme environments.Thermotoga species are rod-shaped, gram-negative, non-sporulating hyperthermophiles that form a sheath-like envelope called a toga. They ferment sugars or starch, producing lactate, acetate, CO₂, and H₂, and can also grow via anaerobic respiration using H₂ and ferric iron. Found in hot springs and hydrothermal vents, over 20% of their genes show strong...
Limits to Natural Selection01:38

Limits to Natural Selection

Organisms that are well-adapted to their environment are more likely to survive and reproduce. However, natural selection does not lead to perfectly adapted organisms. Several factors constrain natural selection.For one, natural selection can only act upon existing genetic variation. Hypothetically, redtusks may enhance elephant survival by deterring ivory-seeking poachers. However, if there are no gene variants—or alleles—for redtusks, natural selection cannot increase the prevalence of...
Non-LTR Retrotransposons03:18

Non-LTR Retrotransposons

As the name suggests, non-LTR retrotransposons lack the long terminal repeats characteristic of the LTR retrotransposons. Additionally, both LTR and non-LTR retrotransposons use distinct mechanisms of mobilization. Non-LTR retrotransposons are further divided into two classes - Long interspersed nuclear elements (LINEs) and short interspersed nuclear elements (SINEs), both of which occur abundantly in most mammals, including humans. Some of the active non-LTR retrotransposons in humans are L1...
Predator-Prey Interactions02:39

Predator-Prey Interactions

Predators consume prey for energy. Predators that acquire prey and prey that avoid predation both increase their chances of survival and reproduction (i.e., fitness). Routine predator-prey interactions elicit mutual adaptations that improve predator offenses, such as claws, teeth, and speed, as well as prey defenses, including crypsis, aposematism, and mimicry. Thus, predator-prey interactions resemble an evolutionary arms race.Although predation is commonly associated with carnivory, for...

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相关实验视频

Updated: Jun 14, 2026

Chemical Isolation, Quantification, and Separation of Skin Lipids from Reptiles
07:55

Chemical Isolation, Quantification, and Separation of Skin Lipids from Reptiles

Published on: February 7, 2019

一个南方暴君爬行动物爬行动物.

Roger B J Benson1, Paul M Barrett, Tom H Rich

  • 1Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK. rbb27@cam.ac.uk

Science (New York, N.Y.)
|March 27, 2010
PubMed
概括

来自澳大利亚的化石证据显示,类动物的祖先类动物在全球分布的时间比以前想象的要早得多. 这一发现挑战了这些顶峰捕食者在白纪早期仅限于北半球的观点.

科学领域:

  • 古生物学的古生物学
  • 脊椎动物古生物学 脊椎动物古生物学
  • 中生代生态系统 中生代生态系统

背景情况:

  • 龙类动物是白纪晚期的顶级捕食者,主宰了劳拉西亚.
  • 龙类动物的早期进化和分布不太清楚,化石主要在北半球发现.
  • 提拉诺类动物之前的1亿年的血统在很大程度上仍未被记录.

研究的目的:

  • 为了研究龙类动物的早期分布和进化.
  • 为了确定类恐龙在白纪早期是否仅限于劳拉西亚.
  • 为了了解龙体图的起源.

主要方法:

  • 来自澳大利亚维多利亚的早期白纪的化石阴茎骨的分析.
  • 澳大利亚化石的形态比较与已知的类动物和类动物标本.
  • 基于化石证据的古生物学地理评估.

主要成果:

  • 发现了澳大利亚的类恐龙标本,该标本来自早期白纪晚期.
  • 该标本表现出先进的暴龙类形态,尽管它的小尺寸.
  • 这一发现表明,龙类动物并不仅限于劳拉西亚.

结论:

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Last Updated: Jun 14, 2026

Chemical Isolation, Quantification, and Separation of Skin Lipids from Reptiles
07:55

Chemical Isolation, Quantification, and Separation of Skin Lipids from Reptiles

Published on: February 7, 2019

Using Enclosed Y-Mazes to Assess Chemosensory Behavior in Reptiles
06:15

Using Enclosed Y-Mazes to Assess Chemosensory Behavior in Reptiles

Published on: April 7, 2021

Reproductive Techniques for Ovarian Monitoring and Control in Amphibians
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Reproductive Techniques for Ovarian Monitoring and Control in Amphibians

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  • 早期白时期的类恐龙,以短臂和坚固的头骨为特征,很可能在全球分布.
  • 在巨型Tyranosaurids的兴起之前,存在着一个具有Tyranosaurid-like体型规划的小型Tyranosauroid的世界级品种.
  • 这种澳大利亚化石为这些成功的捕食者的早期古生物学地理提供了关键证据.