首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   122799篇
  免费   8288篇
  国内免费   535篇
耳鼻咽喉   1312篇
儿科学   3630篇
妇产科学   2059篇
基础医学   16372篇
口腔科学   2199篇
临床医学   12153篇
内科学   26015篇
皮肤病学   1479篇
神经病学   11940篇
特种医学   3814篇
外国民族医学   1篇
外科学   17682篇
综合类   1655篇
现状与发展   1篇
一般理论   156篇
预防医学   10702篇
眼科学   3308篇
药学   8720篇
  1篇
中国医学   278篇
肿瘤学   8145篇
  2023年   562篇
  2022年   884篇
  2021年   2368篇
  2020年   1410篇
  2019年   2401篇
  2018年   2802篇
  2017年   2039篇
  2016年   2379篇
  2015年   2743篇
  2014年   3958篇
  2013年   5557篇
  2012年   8470篇
  2011年   9095篇
  2010年   4966篇
  2009年   4631篇
  2008年   8024篇
  2007年   8514篇
  2006年   8070篇
  2005年   8121篇
  2004年   7666篇
  2003年   7067篇
  2002年   6816篇
  2001年   1192篇
  2000年   890篇
  1999年   1228篇
  1998年   1452篇
  1997年   1224篇
  1996年   949篇
  1995年   945篇
  1994年   799篇
  1993年   786篇
  1992年   664篇
  1991年   607篇
  1990年   540篇
  1989年   501篇
  1988年   502篇
  1987年   484篇
  1986年   419篇
  1985年   497篇
  1984年   562篇
  1983年   522篇
  1982年   697篇
  1981年   610篇
  1980年   534篇
  1979年   368篇
  1978年   347篇
  1977年   348篇
  1976年   291篇
  1975年   272篇
  1974年   279篇
排序方式: 共有10000条查询结果,搜索用时 173 毫秒
131.
BACKGROUND CONTEXT: Diastematomyelia is a split-cord malformation often accompanied by other cord or column anomalies. PURPOSE: To report on an adult patient with diastematomyelia and discuss the embryological basis and related developmental sequelae of this split-cord malformation. STUDY DESIGN: Case report. METHODS: A summary of the management of a 54-year-old woman with recent clinical symptomatology related to an undiagnosed split-cord malformation is presented with accompanying literature review. RESULTS: A rare adult presentation of diastematomyelia with accompanying intradural extramedullary epidermoid tumor was repaired with resection of the soft-tissue mass and excision of the fibro-osseous septum. CONCLUSION: Initial presentation of diastematomyelia is rarely seen in adults; accompanying pathology includes scoliosis, tethered cord, and intradural tumors. Effective treatment involves identification of the primary pathology.  相似文献   
132.
133.
134.
135.
136.
137.
The recent global resurgence of mumps has drawn attention to the continued need for robust mumps immunization programs. Unfortunately, some vaccines derived from inadequately attenuated vaccine strains of mumps virus have caused meningitis in vaccinees, leading to withdrawal of certain vaccine strains from the market, public resistance to vaccination, or in some cases, cessation of national mumps vaccination programs. The most widely implicated mumps vaccine in cases of postvaccination meningitis is derived from the Urabe AM9 strain, which remains in use in some countries. The Urabe AM9 vaccine virus has been shown to exhibit a considerable degree of nucleotide and amino acid heterogeneity. Some studies have specifically implicated variants containing a lysine residue at amino acid position 335 in the hemagglutinin-neuraminidase (HN) protein with neurotoxicity, whereas a glutamic acid residue at this position was associated with attenuation. To test this hypothesis we generated two modified Urabe AM9 cDNA clones coding either for a lysine or a glutamic acid at position 335 in the HN gene. The two viruses were rescued by reverse genetics and characterized in vitro and in vivo. Both viruses exhibited similar growth kinetics in neuronal and non-neuronal cell lines and were of similar neurotoxicity when tested in rats, suggesting that amino acid 335 is not a crucial determinant of Urabe AM9 growth or neurovirulence.  相似文献   
138.
139.
Mutations in PAX6/Pax6 lead to a variety of ocular anomalies in humans and mice. The aim of the study was to characterise the ocular abnormalities caused by the missense Pax6Leca4 mutation and compare them to published observations on Pax6 alleles that are functionally equivalent to Pax6 null alleles (such as Pax6Sey and Pax6Sey-Neu) and human inherited eye diseases. Ocular features of homozygous Pax6Leca4/Leca4 and heterozygous Pax6Leca4/+ embryos at E12.5-E18.5, heterozygous Pax6Leca4/+ young mice at P18 and heterozygous Pax6Leca4/+ adults at 12 weeks were analysed histologically with their wild-type Pax6+/+ littermates. Homozygous Pax6Leca4/Leca4 fetuses died perinatally with no eyes although an optic cup rudiment with pigmented cells developed. Pax6Leca4/+ mice were microphthalmic and a range of other severe ocular phenotypes affected both the anterior and the posterior segments. In contrast to Pax6+/−, the Pax6Leca4/+ eyes had no goblet cells in the corneal epithelium, the iris was not hypoplastic and there was no lens-corneal epithelial plug. However, microphthalmia was more severe, corneal vascularisation occurred earlier (during fetal stages), pigmented cells were present in the vitreous and corneal stroma and the ciliary body was malformed or abnormal. These results show that, although Pax6Leca4/+ lacked some eye abnormalities commonly seen in Pax6Sey/+ and Pax6Sey-Neu/+ eyes, in most respects their eyes were more severely affected. These differences probably reflect both differences between the Pax6Leca4 and the Pax6Sey-Neu mutations and differences in modifier gene expression in different genetic backgrounds. The presence of pigmented cells in the cornea is a novel observation. Some Pax6Leca4/+ ocular abnormalities were similar to those present in human Peters' anomaly and persistent hyperplastic primary vitreous (PHPV) so Pax6Leca4/+ mice provide a useful model for some inherited eye diseases.  相似文献   
140.
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