What is scientific sketch? So far, there is no unified definition. Many scientific sketches in Chinese textbooks can only be said to be a kind of popular science exposition, and they are scientific sketches in a broad sense. Some people say: "Scientific sketch is an expository article written in literary style with scientific and technological knowledge as the theme." In fact, scientific sketch has a deeper connotation. Cheng Min thinks: "As the offspring of popular science discourses and essays, scientific essays have their own unique pursuit from content, form and language to ideological implication and aesthetic taste of works." The famous popular science writers of the older generation all have their own opinions. Zhou Zuoren, a popular science writer, said: "The so-called scientific sketch should be a sketch with scientific content and the beauty of an article. If it is based on natural history or written with a scientific outlook on life, it seems to be just an article. " Gao Shiqi, a famous writer of scientific sketches in China, said: "Scientific sketches are a variant of scientific literature, a light cavalry in popular science works and a unique genre in China (lighting the lamp of ideals and hopes)." Starting from the pursuit of the older generation of popular science writers, after 70 years of practice and development, China's unique popular science prose has formed its own model. This model is still developing and innovating in today's advocating science. First of all, scientific papers are an important category in popular science works, and scientificity is the cornerstone of scientific papers. The so-called scientificity means not only spreading scientific knowledge in scientific sketches, but also "promoting scientific spirit, scientific thought and advocating scientific methods." Secondly, scientific sketches should be literary, tasteful and personal. Therefore, scientific sketches should make full use of various literary means to make science an interesting and easily accepted thing. Scientific sketches should fully inherit and carry forward the diverse and flexible features of essays and essays, talk about science in the form of stories, dialogues, leisurely and elegant essays, tell the contents and objects of science in a personalized and story-like way, and endow inanimate objects or animals and plants with humanity and human feelings through various anthropomorphic means, thus vividly showing the original rigid and profound scientific principles in the form of stories. Scientific sketch, like all modern narrative styles, cannot design so-called "characters" or find "roles" for all subjects. In the absence of stories and plots, dig out the materials with scientific spirit and scientific thought connotation, reveal the cause and effect of the object, and explain its internal relationship. This is also the normal form of scientific sketch. Scientific sketches can be vividly described and recorded in prose, and can also be explained and explained in expository texts, but most of them are narrative texts. The proper insertion of humorous materials, the quotation of various literary poems in the text, the interesting beginning, the meaningful ending and so on are all realized through narration. Literariness is the soul of scientific sketches. A popular science writer said that there is no boring science in the world, only boring narration. Many popular science writers are good at using folk proverbs, sayings or historical allusions, quoting them widely, making use of the topic, setting off interest, comparing pictographs and rendering literary talent. Their scientific sketches often start from a specific sensible particle and give people a dynamic concept. This vivid and ingenious wit stems from the eloquence of scientific argumentation, the extension of logical power, the accuracy of knowledge and the standardization of quoted words. The harmony between nature, society and human beings is the ideal peak of human beings, which makes scientific knowledge intimate and touchable, and can appreciate wisdom and pleasure. This is the profound significance. Finally, scientific sketches should be "small". As Liu Kun said: "Scientific sketches are the freest in subject matter. As long as they are closely related to public life, whether it is a natural phenomenon or a social phenomenon, you can choose a sketch to describe them. It's really' from flies to the universe'. But its task is to correct the mistakes of common sense, and the solemn and scientific explanation should not be distorted and covered up. At the same time, he wants to give up the language of scientists and try to use words commonly used by the public. Don't be too serious, so that ordinary people don't think this is a big truth, but talk about the familiar gossip around their lives. You should also add some humor and try to take various forms. " That is to say, in terms of content, although scientific sketches must also take scientific phenomena as the basic object, they cannot follow systematic theories and comprehensive knowledge like popular science discourses, scientific works and textbooks. It requires the dissemination of scientific knowledge to be relatively simple and easy to understand, which is full of aesthetic value, so that scientific sketches can obtain the exquisite conception of prose sketches while disseminating scientific knowledge. Scientific sketch uses image thinking mode to explain scientific truth vividly. In terms of vocabulary, scientific sketches try to replace abstract vocabulary with vivid, dynamic and sensitive vocabulary. Like literary genre, it also freely uses function words such as exclamations and modal particles, reduplication words, onomatopoeia words and Er-hua words, so as to obtain the language effect of imitating expression, emphasizing tone and strengthening feelings. It also uses word escape and synonyms to make the expression more vivid, changeable and emotional. In sentence selection, scientific sketches inherit the characteristics of prose, such as smartness and agility. Even sentences, odd sentences, long sentences, short sentences, complex sentences and simple sentences are varied and natural, which greatly enhances the vividness of the language. In addition, in rhetoric, scientific sketches can use almost all the ways that can be seen in literary genres, which will undoubtedly bring a lot of vividness and beauty to the style. Scientific sketches promote the scientific spirit and eulogize the beauty and affection of the world with exquisite articles. Although the multiple value orientations of scientific sketch demand materials, they also bring fresh and bright colors to the style. Due to the requirements of telling stories, telling plots, personifying materials and the dependence of thinking on association, imagination and fantasy, the language of scientific sketches has a very broad free space on the premise of accurately expressing scientific content. Therefore, exploring the inner and deep scientific methods and spirit of the object and weaving beautiful stories with human feelings and philosophical thoughts have become the basis of scientific sketches. Scientific sketches pursue the perfect unity of science, ideology and literariness. Popular science writers often describe the things around them, integrate rich and accurate scientific knowledge, historical knowledge and cultural knowledge, show high scientific, ideological and literary nature, express strong scientific interest and profound philosophy, and make the cognitive value and appreciation value perfectly unified. Explanatory text definition Explanatory text is a common style, and there are many Chinese textbooks in primary schools, such as the texts "Whale" and "New Glass" we learned before. So, what is expository? Simply put, it is an article that explains things. Explanatory writing is an article genre with explanation as its main expression. It objectively explains the appearance, structure, nature, characteristics, scope, category, source, reason, relationship and function of things, thus clarifying the content and form, essence and law of things and enabling people to acquire relevant knowledge.