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In 1798, at the age of 19, a self-taught British chemist named Humphry Davy got a job testing newly discovered gases to see if any of them could cure diseases. Fearlessly testing gases on himself, he found that one — nitrous oxide — made people laugh. This discovery brought Davy to the attention of the world, made "laughing gas” a party favorite — and led to a new job at the Royal Institution in London. There, Davy dazzled audiences with his popular lectures and turned the newly discovered battery into a powerful tool in the search for new elements. But with his attention diverted by electricity, elements and lecturing, Davy failed to follow up on one of his own observations, thereby condemning thousands around the world to decades of needless surgical pain.
    Просмотров: 37 | Дата: 03.08.2021

At the age of 25, Antoine Lavoisier bought a share in a consortium that collected taxes for the king of France. His work as a tax administrator not only made him a wealthy man but also influenced his approach to science. Like a bookkeeper, he paid obsessive attention to the weights of his chemical ingredients before and after each reaction — an approach that became a model for all future chemists. Before and after work each day, Lavoisier spent hours in a private laboratory equipped with the finest instruments money could buy. One day a week he welcomed others into his lab to take part in his ambitious experiments, but his most important collaborator was his wife, Marie Anne, who brought her own extraordinary talents to their partnership.
    Просмотров: 16 | Дата: 03.08.2021

Though best known today for his discovery of the gas oxygen, Joseph Priestley was a man of wide interests and boundless curiosity. Born in Yorkshire, about 200 miles north of London, he was raised outside England’s state religion and would eventually become one of the founders of the Unitarian Church. While holding a variety of jobs as a minister, teacher, lecturer and tutor, he wrote prolifically on subjects ranging from education and theology to politics and science. But it was Priestley’s idea for a book about electricity that led to his warm friendship with Benjamin Franklin — and inspired him to become a scientist in his own right.
    Просмотров: 17 | Дата: 03.08.2021

    Просмотров: 27 | Дата: 27.07.2021

Описание: Скорее всего пользователь ввел неверный пароль максимальное количество раз, которое указано в профиле пользователя.

Параметр FAILED_LOGIN_ATTEMPTS или пользователь был заблокирован DBA.
Решение: Ждем PASSWORD_LOCK_TIME или начинаем действовать, если конечно у вас есть права DBA. 
  1. Запускаем командную строку и пишем: sqlplus \sys as sysdba;
  2. Вводим пароль (по умолчанию для логина sys пароль sys)
  3. alter user [USER NAME] account unlock; где  [USER NAME] - Имя заблокированного пользователя.
  4. Пробуем подключится.
    Просмотров: 37 | Дата: 20.07.2021

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