571 résultats pour "presence"
- Livre du professeur 4eme hatier
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Parkinson Disease.
III SYMPTOMS Parkinson disease most notably affects motor control (muscle activity). The disease progresses differently for each individual—symptoms develop swiftly in some peopleand slowly in others. Some Parkinson patients may develop problems that affect their intellect or ability to reason, or they may suffer from depression or anxiety. A Motor Control Problems Doctors look for the presence of four principal symptoms in patients they suspect may have Parkinson disease. Tremor (the involun...
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Radioactivity
I
INTRODUCTION
Marie Curie
Working with her husband, Pierre Curie, French physicist Marie Curie discovered the radioactive elements polonium and
radium in 1898.
Rutherford when he allowed an alpha-emitting substance to decay near an evacuated thin-glass vessel. The alpha particles were able to penetrate the glass and werethen trapped in the vessel, and within a few days the presence of elemental helium was demonstrated by use of a spectroscope. Beta particles were subsequentlyshown to be electrons, and gamma rays to consist of electromagnetic radiation of the same nature as X rays but of considerably greater energy. A The Nuclear Hypothesis Rutherford...
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Air Pollution.
Several pollutants attack the ozone layer. Chief among them is the class of chemicals known as chlorofluorocarbons (CFCs), formerly used as refrigerants (notably in airconditioners), as agents in several manufacturing processes, and as propellants in spray cans. CFC molecules are virtually indestructible until they reach thestratosphere. Here, intense ultraviolet radiation breaks the CFC molecules apart, releasing the chlorine atoms they contain. These chlorine atoms begin reacting withozone, br...
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Soil.
I
INTRODUCTION
Soil, the loose material that covers the land surfaces of
an exchange between plants and the atmosphere, as oxygen diffuses into the soil and is used by roots for respiration. In turn, the resulting carbon dioxide diffusesthrough pore spaces and returns to the atmosphere. This exchange is most efficient in soils with a high degree of porosity. For farmers, gardeners, landscapers, andothers with a professional interest in soil health, the process of aeration—making holes in the soil surface to permit the exchange of air—is a crucial activity. Theburrowi...
- L'odyssée d'homère
- Insanity planning
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Chemical Reaction - chemistry.
Many groups of elements occur so often as ions that they are given names: nitrate, NO 3-; sulfate, SO 42-; and phosphate, PO 43-. The suffix -ate usually indicates the presence of oxygen. The positive ion, NH 4+, is called ammonium, as in NH 4Cl, ammonium chloride, or (NH 4)3PO4, ammonium phosphate. Rules for naming more complicated compounds exist, but many compounds have been given trivial names—for example, Na 2B4O7·10 H 2O, borax—or proprietary names—F(CF 2)nF, Teflon. These nonsystemat...
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- victor hugo napoléon le petit
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Radar.
gathers the weak returning radar signals and converts them into an electric current. Because a radar antenna may both transmit and receive signals, the duplexerdetermines whether the antenna is connected to the receiver or the transmitter. The receiver determines whether the signal should be reported and often does furtheranalysis before sending the results to the display. The display conveys the results to the human operator through a visual display or an audible signal. B1 The Antenna The rec...
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Judaism.
is learned or memorized”), the earliest document of rabbinic literature, edited in Palestine at the turn of the 3rd century. Subsequent rabbinic study of the Mishnah inPalestine and Babylonia generated two Talmuds (“that which is studied”; also called Gemera, an Aramaic term with the same meaning; see Talmud), wide-ranging commentaries on the Mishnah. The Babylonian Talmud, edited about the 6th century, became the foundation document of rabbinic Judaism. Early rabbinic writings also include exe...
- la division du travail
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Ottoman Empire .
fleets at Suez, Egypt; though the Portuguese were not expelled, Selim did manage to prevent the establishment of a total Portuguese monopoly over the spice trade. Selim I died in 1520 after having spent most of his short reign on matters pertaining to the east. His son and successor Süleyman I (reigned 1520-1566) again turnedthe attention of the Ottomans to the west. In August 1521 Süleyman, later known as Süleyman the Magnificent, opened the road to Hungary by capturing Belgrade, aHungarian str...
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Ottoman Empire - History.
fleets at Suez, Egypt; though the Portuguese were not expelled, Selim did manage to prevent the establishment of a total Portuguese monopoly over the spice trade. Selim I died in 1520 after having spent most of his short reign on matters pertaining to the east. His son and successor Süleyman I (reigned 1520-1566) again turnedthe attention of the Ottomans to the west. In August 1521 Süleyman, later known as Süleyman the Magnificent, opened the road to Hungary by capturing Belgrade, aHungarian str...
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planétologie - astronomie.
été la première indication de l’existence d’un champ magnétique très intense sur une planète autre que la Terre (le champ magnétique de Jupiter est 17 000 fois supérieur àcelui de la Terre). Le rayonnement radio décimétrique (de fréquence comprise entre 1 000 MHz et 3 000 MHz) émis par Jupiter est interprété comme l’émission synchrotronde particules chargées relativistes, piégées dans le champ magnétique jovien interne. Ainsi, les ceintures de radiations joviennes ont-elles été découvertes deux...
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Roman Empire .
A Government Augustus did not derive his power from any single office, but from the authority of his name and his victory. In fact, he carefully pieced together a patchwork of powersthat allowed him to be an absolute ruler and yet avoid the hatred Caesar aroused as dictator. In Latin, the name Augustus implies both political authority and religiousrespect. The Romans had for some time called Octavian imperator , a title once awarded to victorious generals that soon became associated with the r...
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Roman Empire - History.
A Government Augustus did not derive his power from any single office, but from the authority of his name and his victory. In fact, he carefully pieced together a patchwork of powersthat allowed him to be an absolute ruler and yet avoid the hatred Caesar aroused as dictator. In Latin, the name Augustus implies both political authority and religiousrespect. The Romans had for some time called Octavian imperator , a title once awarded to victorious generals that soon became associated with the r...
- Pierre et Jean
- Devoir
- 861 SUJETS-TEXTES DE L’ÉPREUVE DE PHILOSOPHIE AU BACCALAURÉAT
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Histoire de la littérature française - cours
JEAN-JACQUES ROUSSEAU (1712-1778) Les œuvres principales de Rousseau se groupent naturellement en trois catégories, qui correspondent à trois moments de sa pensée: 1. Œuvres de critique négative : Les Discours sur le rétablissement des sciences et des arts, Le Discours sur l’origine et le fondement de l’inégalité parmi les hommes, La Lettre a Dalembert sur les spectacles 2. Œuvres constructives : La Nouvelle Héloïse, Le Contrat social, L’Emile 3. Œuvres autobiographiques dont...