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具有下列化学结构的是哪一个药物
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下列哪项叙述与氯霉素不符
Africas When many people hear the word "Africa", inevitably they picture steaming jungles and gorillas and other wild animals. Hollywood films have shrunk the public image of this immense, varied continent into a small segment of its actual diversity. To have a more accurate picture of the whole continent, however, one should remember that the continent can be roughly divided into three Africas: the northern desert areas, the southeastern grasslands, and the tropical jungles to the southwest, each with its distinct climate and terrain and with a style of life suited to the environment. The northern regions have the environment and living patterns of the desert. Egypt, Libya, Algeria, and Morocco have hot, dry climates with very little land suited to farming. Green fields cannot be easily seen. Therefore, the population tends to be clustered into cities along rivers or the seacoast or into smaller settlements near oases. For thousands of years, people have lived in this vast region, relying partly on what the land could offer such as crops and animals they could raise and partly on trade with Europe. The southeastern grasslands provide a better environment for animal life and for some kinds of crops. Many wild animals inhabit the plains in this region—elephants, giraffes, rhinoceros, antelopes, zebras, and lions. The people in this area have long been expert cattle raisers and experienced hunters. Tea, coffee, cotton, cashew nuts, and tobacco are some of the main products grown in this region. Fishing also provides some food and income for people along the coast. The population here is less concentrated in cities and towns than in the north, but tends to be denser in areas where adequate rainfall and fertile soil make farming possible. West Africa is the region closest to the Hollywood image of mysterious jungles. As in the other two regions, the way people make a living depends upon their environment. This does not mean that most of the people live in grass huts in the jungle. In fact, such nations as Nigeria have become highly modernized by income from oil, timber, and minerals. Most of the western countries have some farming that provides food and income; sugar cane, coffee, and tobacco are the important cash crops, while bananas, rice, and corn are raised for food. Fishing in the rivers and along the coast also accounts for food and income, and precious stones, especially diamonds, enhance the economy of countries like Angola and the Ivory Coast. Even a superficial look at the major regions of Africa shows that it is a continent with varied environments. Although most of the continent is tropical in its range of temperature, the climate ranges from deserts to rain forests. Similarly, human lifestyles vary from the simplest rural villages to industrial cities, both new and ancient. Contrary to the myth, however, jungle life makes up only a very small portion of the whole of Africa.
青霉素钠在酸性溶液加热条件下生成
克拉霉素与下列哪个药物作用相类似
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