首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
Rapid population growth in China during the 1950s and ''60s led to the "late, long, few" policy of the 1970s and a dramatic reduction in the total fertility rate. However, population growth remained too high for the economic targets of Deng Xiao Ping''s reforms, so the one child family policy was introduced in 1979 and has remained in force ever since. The strategy is different in urban and rural areas, and implementation varies from place to place depending on local conditions. The policy has been beneficial in terms of curbing population growth, aiding economic growth, and improving the health and welfare of women and children. On the negative side there are concerns about demographic and sex imbalance and the psychological effects for a generation of only children in the cities. The atrocities often associated with the policy, such as female infanticide, occur rarely now. China may relax the policy in the near future, probably allowing two children for everyone.  相似文献   

7.
The Future of the Past: Archeologists, Native Americans, and Repatriation. Tamara L. Bray. New York: Garland Publishing. 2001. 252 pp.  相似文献   

8.
9.
10.
11.
12.
13.
The alphaviruses: gene expression, replication, and evolution.   总被引:41,自引:0,他引:41       下载免费PDF全文
The alphaviruses are a genus of 26 enveloped viruses that cause disease in humans and domestic animals. Mosquitoes or other hematophagous arthropods serve as vectors for these viruses. The complete sequences of the +/- 11.7-kb plus-strand RNA genomes of eight alphaviruses have been determined, and partial sequences are known for several others; this has made possible evolutionary comparisons between different alphaviruses as well as comparisons of this group of viruses with other animal and plant viruses. Full-length cDNA clones from which infectious RNA can be recovered have been constructed for four alphaviruses; these clones have facilitated many molecular genetic studies as well as the development of these viruses as expression vectors. From these and studies involving biochemical approaches, many details of the replication cycle of the alphaviruses are known. The interactions of the viruses with host cells and host organisms have been exclusively studied, and the molecular basis of virulence and recovery from viral infection have been addressed in a large number of recent papers. The structure of the viruses has been determined to about 2.5 nm, making them the best-characterized enveloped virus to date. Because of the wealth of data that has appeared, these viruses represent a well-characterized system that tell us much about the evolution of RNA viruses, their replication, and their interactions with their hosts. This review summarizes our current knowledge of this group of viruses.  相似文献   

14.
15.
The Interactive Fly: gene networks, development and the Internet.   总被引:6,自引:0,他引:6  
  相似文献   

16.
The enormous growth of the Internet and the World Wide Web has made these two technologies an important potential adjunct to cost-effective health care research and delivery. This article surveys some recent developments in telecommunications, networking and artificial intelligence that are likely to have a significant impact on improving the efficiency and quality of future health care. Issues discussed include: clinical record keeping on the Internet, Internet-assisted medical diagnosis, privacy and security matters, financial transactions, digital money, bandwidth concerns, multimedia (music, audio and video) information delivery via the Internet, intellectual property, and the concept of Information Philanthropy.  相似文献   

17.
The fungal vacuole: composition, function, and biogenesis.   总被引:86,自引:4,他引:82  
The fungal vacuole is an extremely complex organelle that is involved in a wide variety of functions. The vacuole not only carries out degradative processes, the role most often ascribed to it, but also is the primary storage site for certain small molecules and biosynthetic precursors such as basic amino acids and polyphosphate, plays a role in osmoregulation, and is involved in the precise homeostatic regulation of cytosolic ion and basic amino acid concentration and intracellular pH. These many functions necessitate an intricate interaction between the vacuole and the rest of the cell; the vacuole is part of both the secretory and endocytic pathways and is also directly accessible from the cytosol. Because of the various roles and properties of the vacuole, it has been possible to isolate mutants which are defective in various vacuolar functions including the storage and uptake of metabolites, regulation of pH, sorting and processing of vacuolar proteins, and vacuole biogenesis. These mutants show a remarkable degree of genetic overlap, suggesting that these functions are not individual, discrete properties of the vacuole but, rather, are closely interrelated.  相似文献   

18.
19.
20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号