全文获取类型
收费全文 | 74477篇 |
免费 | 3302篇 |
专业分类
各国政治 | 4557篇 |
工人农民 | 3018篇 |
世界政治 | 6612篇 |
外交国际关系 | 3900篇 |
法律 | 36681篇 |
中国共产党 | 11篇 |
中国政治 | 768篇 |
政治理论 | 21276篇 |
综合类 | 956篇 |
出版年
2021年 | 422篇 |
2020年 | 1180篇 |
2019年 | 1527篇 |
2018年 | 1747篇 |
2017年 | 2061篇 |
2016年 | 2231篇 |
2015年 | 1852篇 |
2014年 | 2121篇 |
2013年 | 10646篇 |
2012年 | 1775篇 |
2011年 | 1933篇 |
2010年 | 1923篇 |
2009年 | 2136篇 |
2008年 | 1926篇 |
2007年 | 1924篇 |
2006年 | 2053篇 |
2005年 | 1945篇 |
2004年 | 1822篇 |
2003年 | 1662篇 |
2002年 | 1667篇 |
2001年 | 2058篇 |
2000年 | 1748篇 |
1999年 | 1518篇 |
1998年 | 1215篇 |
1997年 | 1061篇 |
1996年 | 1018篇 |
1995年 | 980篇 |
1994年 | 1020篇 |
1993年 | 1018篇 |
1992年 | 1141篇 |
1991年 | 1182篇 |
1990年 | 1096篇 |
1989年 | 1146篇 |
1988年 | 1107篇 |
1987年 | 1126篇 |
1986年 | 1135篇 |
1985年 | 1161篇 |
1984年 | 1046篇 |
1983年 | 1109篇 |
1982年 | 957篇 |
1981年 | 909篇 |
1980年 | 722篇 |
1979年 | 808篇 |
1978年 | 639篇 |
1977年 | 584篇 |
1976年 | 543篇 |
1975年 | 463篇 |
1974年 | 466篇 |
1973年 | 460篇 |
1972年 | 407篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
851.
The superheated debate over breast implants awakened a sleeping giant of an issue clouding "medical devices"--the government's clumsy nomenclature for any medical product that is not a drug, from breast implants and artificial hips to X-ray machines and surgical thread. Some 130 categories of high-risk devices are in use with little or no proof of safety, reliability or effectiveness. All appeared before 1976, the year that the Food and Drug Administration got the authority to regulate such products. Under activist chief David Kessler and with added clout from a 1990 law, the FDA plans to scrutinize the entire 130-item list. Five will get special attention starting early next year: saline-filled breast implants, inflatable penile implants, testicular implants, heart-bypass pumps and cranial stimulators. U.S. News has looked at all five devices, using FDA data obtained through the Freedom of Information Act. In-depth computer analysis suggested that penile implants deserve closer examination. Why is clear from the following report. 相似文献
852.
853.
854.
Weinstein J 《Studies in Comparative International Development (SCID)》1992,26(4):29-44
The numerical and qualitative aspects of the growth of the Indians urban population are discussed with the benefit of data from the last 4 censuses. Thinkers exemplified by M.K. Gandhi believe that urban growth erodes Indian culture, while opponents argue that India's traditional way of life deserves to be obliterated. The "mechanics" of erosion of Indian culture is discussed under 5 headings: its locus, speed, direction, type of population shifts, and types of cities affected by growth. The village, which is the principal locus of Indian culture, is the locus affected by urbanization. The quantitative estimate of urbanization is extremely rapid: between 1951 and 1988, the urban population grew from 62 to 217 million. In this period rural numbers grew from 295 to 618 million. Because of the hugh natural increase of the rural population, the proportion of the urban population grew only from 17.3% to 23.3%. The direction of change is described as a process or cultural accretion or "interpenetration" rather than replacement of tradition by urban culture. Populations shifts account for a large amount of urban increase, a net rise in urban sector of 15 million/decade. While the 4 largest cities received the most immigrants, growing at 3.16%, the intermediate 6 cities with populations 1 million in 1981 grew even faster, at 3.48%. It is likely that India's population after the 1991 census is complete will be 910 million, with 27% urban. 相似文献
855.
856.
857.
858.
859.
860.
J Beck 《Journal of forensic sciences》1992,37(1):349-355
This paper provides a brief biography of Luke S. May (1886-1965), whose pioneering work in forensic science in the United States has not received full recognition. May began as a private detective in Salt Lake City, Utah, shortly after the turn of the century and later established his own agency, the Revelare International Secret Service, which he moved to Seattle, Washington, in 1919. Although basically self-taught in scientific matters, May built a solid reputation among police agencies and attorneys in the Pacific Northwest and Western Canada as a serious and effective scientific investigator in the era before public crime laboratories. This reputation as "America's Sherlock Holmes" also led to his being consulted on the establishment of the first American crime laboratory at Northwestern University in Chicago, Illinois, and on a laboratory for the Royal Canadian Mounted Police at Regina, in Saskatchewan, Canada. He contributed to a landmark case of court acceptance of toolmark identification, invented specialized instruments, and founded an institute to teach scientific criminal investigation to police officers. His earliest associates were John L. Harris and J. Clark Sellers, both of whom became recognized document examiners on the West Coast and were followed by a second and a third generation of practitioners. 相似文献