维普中文科技期刊数据库

Apabi数字资源平台

万方数据知识服务平台

超星数字图书馆

侵蚀性葡萄胎可发生在流产后

绒毛膜癌可发生在葡萄胎之后

绒毛膜癌最早出现的是脑转移

绒毛膜癌最常见的死因是肺转移

前次妊娠为异位妊娠，不发生绒毛膜癌

订阅号

服务号

企业号

超星数字图书馆

万方数据知识服务平台

CNKI中国知网

Apabi数字资源平台

沿着光纤的中轴线直线传播

沿着光纤的外壁多次折射传播

沿着光纤的内壁多次反射传播

沿着光纤螺旋式的曲线传播

微博打破了传统媒体的“专业主义壁垒”，对中国社会的影响越来越大

微博的兴起，可让任何人都能从新闻信息的受众变为信息的传播者

微博对于突发事件的报道比传统媒体更快捷，更易抢得报道先机

微博作为信息传播的终端开创了一个更为便捷的话语平台

CNKI中国知网

Apabi数字资源平台

万方数据知识服务平台

超星数字图书馆

Dialects A dialect is a variety of a language spoken by an identifiable subgroup of people. Traditionally, linguists have applied the term dialect to geographically distinct language varieties, but in current usage the term can include speech varieties characteristic of other socially definable groups. Determining whether two speech varieties are dialects of the same language, or whether they have changed enough to be considered distinct languages, has often proved a difficult and controversial decision. Linguists usually cite mutual intelligibility as the major criterion in making this decision. If two speech varieties are not mutually intelligible, then the speech varieties are different languages if they are mutually intelligible but differ systematically from one another, then they are dialects of the same language. There are problems with this definition, however, because many levels of mutual intelligibility exist, and linguists must decide at what level speech varieties should no longer be considered mutually intelligible. This is difficult to establish in practice. Intelligibility(可理解性) has a large psychological component: If a speaker of one speech variety wants to understand a speaker of another speech variety, understanding is more likely than if this were not the case. In addition, chains of speech varieties exist in which adjacent speech varieties are mutually intelligible, but speech varieties farther apart in the chain are not. Furthermore, sociopolitical factors almost inevitably intervene in the process of distinguishing between dialects and languages. Such factors, for example, led to the traditional characterization of Chinese as a single language with a number of mutually unintelligible dialects. Dialects develop primarily as a result of limited communication between different parts of a community that share one language. Under such circumstances, changes that take place in the language of one part of the community do not spread elsewhere. As a result, the speech varieties become more distinct from one another. If contact continues to be limited for a long enough period, sufficient changes will accumulate to make the speech varieties mutually unintelligible. When this occurs, and especially if it is accompanied by the sociopolitical separation of a group of speakers from the larger community, it usually leads to the recognition of separate languages. The different changes that took place in spoken Latin in different parts of the Roman Empire, for example, eventually gave rise to the distinct modem Romance languages, including French, Spanish, Portuguese, Italian, and Romanian. In ordinary usage, the term dialect can also signify a variety of a language that is distinct from what is considered the standard form. of that language. Linguists, however, consider the standard language to be simply one dialect of a language. For example, the dialect of French spoken in Paris became the standard language of France not because of any linguistic features of this dialect but because Paris was the political and cultural centre of the country.

Social Varieties of Language Sociolects(社会方言) are dialects determined by social factors rather than by geography. Socioleets often develop due to social divisions within a society, such as those of socioeconomic class and religion. In New York City, for example, the probability that someone will pronounce the letter when it occurs at the end of a syllable, as in the word fourth, varies with socioeconomic class. The pronunciation of a final in general is associated with members of higher socioeconomic classes. The same is true in England of the pronunciation of h, as in hat. Members of certain social groups often adopt a particular pronunciation as a way of distinguishin A．Y B．N C．NG

Lingua Franca

Pidgin

Creole

Bilingualism

正确

错误