| 词汇 | bell-jar |
| 释义 | bell jar noun[ C ] uk /ˈbel ˌdʒɑːr/ us /ˈbel ˌdʒɑːr/ a large glass cover shaped like a bell used to cover chemical equipment, especially to prevent any gas from escaping钟形罩 AlexLMX/iStock/Getty Images Plus/GettyImages Laboratory equipment aspirator bubble chamber Buchner funnel Bunsen burner calorimeter condenser flask litmus microscope particle accelerator Petri dish photometer pipette retort stand scope siphon synchrotron syphon test tube transducer Air under a bell jar may be kept dry by means of a basin of sulphuric acid, and gases bubbled through it are freed from water-vapour. By keeping some of this covered with a bell jar for a week or two, so as to retain the moisture, at the end of this time a large crop of the fungus will probably have made its appearance. The whole electrolysis vessel is then placed under a glass bell jar containing dry air, and kept in a refrigerator until again required for use. Examples of bell jarbell jar Bell jars are generally used for classroom demonstrations or by hobbyists, when only a relatively low-quality vacuum is required. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. Although internationally connected, each country's elite lives in a belljar in the sense of being out of touch with its own populace. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. By pumping the air out of the belljar, vacuum is formed. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. She describes her depression as a feeling of being trapped under a belljar, struggling for breath. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. As the family laugh together, it is revealed that they are models inside a belljar on the street stall seen earlier. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. He portrayed the device as a belljar with an opening for the air to enter from below. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. For this reason, a belljar can not be used to contain pressures "above" atmospheric, only below. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. A belljar demonstrates the reason for using a rocket instead of a propeller in the vacuum of space. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. An example of a classroom science experiment involving a belljar is to place a ringing alarm clock under the belljar. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. A belljar is placed on a base which is vented to a hose fitting that can be connected via a hose to a vacuum pump. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. As the air is pumped out of the sealed belljar, the noise of the alarm clock fades, thus demonstrating that the propagation of sound is mediated by the air. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. They also were expensive compared with traditional gardeners' bell jars and cloches. More often, a cloche, or belljar, refers to a covering made of glass or plastic, placed over individual plants to provide similar protection as row cover. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. The table is covered with scarlet velvet, many papers, a casket, an inkwell with two more feather pens, a barometer, a gasometer, a water still and a glass belljar. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. His name apparently refers to bell jars. From Wikipedia This example is from Wikipedia and may be reused under a CC BY-SA license. These examples are from corpora and from sources on the web. Any opinions in the examples do not represent the opinion of the Cambridge Dictionary editors or of Cambridge University Press or its licensors. |
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