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   3084339篇
  免费   220918篇
  国内免费   4442篇
耳鼻咽喉   43232篇
儿科学   100213篇
妇产科学   83188篇
基础医学   450610篇
口腔科学   85756篇
临床医学   278476篇
内科学   590733篇
皮肤病学   68690篇
神经病学   240837篇
特种医学   117483篇
外国民族医学   677篇
外科学   464772篇
综合类   63220篇
现状与发展   13篇
一般理论   1061篇
预防医学   235583篇
眼科学   72179篇
药学   235536篇
  17篇
中国医学   6539篇
肿瘤学   170884篇
  2019年   24429篇
  2018年   34049篇
  2017年   25937篇
  2016年   29201篇
  2015年   32803篇
  2014年   46039篇
  2013年   68966篇
  2012年   94690篇
  2011年   100798篇
  2010年   59885篇
  2009年   56330篇
  2008年   94388篇
  2007年   100799篇
  2006年   101711篇
  2005年   98399篇
  2004年   94259篇
  2003年   90849篇
  2002年   87981篇
  2001年   146009篇
  2000年   150183篇
  1999年   126011篇
  1998年   35475篇
  1997年   31186篇
  1996年   31488篇
  1995年   29611篇
  1994年   27241篇
  1993年   25689篇
  1992年   97049篇
  1991年   94380篇
  1990年   92513篇
  1989年   88999篇
  1988年   81599篇
  1987年   80017篇
  1986年   75151篇
  1985年   71611篇
  1984年   53003篇
  1983年   45025篇
  1982年   26287篇
  1979年   48486篇
  1978年   34108篇
  1977年   29003篇
  1976年   27029篇
  1975年   29561篇
  1974年   35068篇
  1973年   33572篇
  1972年   31730篇
  1971年   29986篇
  1970年   27632篇
  1969年   26467篇
  1968年   24019篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
891.
We applied a forearm flap combined with a gracilis muscle flap for total reconstruction of the lower lip. The motor nerve of the gracilis muscle was repaired to the buccal branch in the cheek. The patient obtained good sphincter function for eating and speaking, and he could inflate a balloon without air leakage.  相似文献   
892.
Clinicopathological and electron microscopical findings of eight cases of enzootic nasal adenocarcinoma of sheep, diagnosed solely in one big flock in Slovenia between years 2001 and 2003 are described. All affected sheep were female, their mean age was 4.5 ± 1.5 years and they either belonged to the Istrian pramenka breed (five sheep) or were crossbreeds (three sheep). Tumours that arose from the ethmoid area of the nasal cavity were unilateral in six cases (75%) and bilateral in two cases (25%). All tumours were classified as adenocarcinomas by histopathological examination and they displayed either a combination of tubular and papillary growth or less often solely tubular proliferation. No metastases were detected in regional lymph nodes, brain or other organs. Electron microscopical studies performed on the reprocessed paraffin‐embedded tissues revealed the presence of the virus‐like particles with an average diameter between 70 and 90 nm.  相似文献   
893.
BACKGROUND: A low level of response to alcohol has been associated with both the genetic constitution of the regulatory region (SLC6A4) of the human serotonin (5-hydroxytryptamine, 5-HT) transporter (5-HTT) and with future alcohol intake and an increased risk for alcoholism. To date, all studies of relevant polymorphisms have been carried out in populations in the United States. METHODS: Data were extracted from a subset (n = 243) of a cohort of children who have been observed since birth through evaluation of the family history of alcoholism and psychosocial risk influences. At age 16 years, the response to alcohol was assessed with the Self-Rating of the Effects of Alcohol (SRE) questionnaire, and the average amount of alcohol intake per month was assessed during the prior 6 months. Additional variables that were measured included the 5-HTT genotype, externalizing behavior, and sociodemographic variables, such as gender and age. RESULTS: The level of response to alcohol was significantly lower among carriers of two long alleles of the 5-HTT regulatory region compared with carriers of one or two short alleles (Mann-Whitney U = 5225.0, p = .005). In a multiple regression analysis, the level of response to alcohol and externalizing behavior but not psychosocial factors significantly predicted the average amount of alcohol intake per month. CONCLUSIONS: This study demonstrates that, independent of the assessed psychosocial variables, the 5-HTT genotype correlated with the level of response to alcohol and predicted alcohol intake among 16-year-old adolescents.  相似文献   
894.
895.
896.
897.
898.
899.
Perforator flaps are perfused through a long vessel whose calibre decreases from its origin to the skin, because all branches have been sealed, resulting in a conduit with resistances in series, rather than a tree with resistances in parallel, as in the normal systemic circulation. This study was planned to assess whether the differences between perforator flap and normal systemic vasculature have an impact on haemodynamic parameters in perforator flaps and on their clinical significance. The study was performed on 10 patients. Echo-colour-Doppler measurement of diameters, velocity of flow and calculations of flow rate were made at the level of flap pedicle artery and skin perforator artery, pre- and post-operatively in each patient. Statistical analysis used the Wilcoxon matched pairs signed sum rank test. Our data show that in the donor area pre-operatively, blood velocity in skin artery perforator is lower that in the corresponding pedicle artery, whereas post-operatively, in perforator flaps, blood velocity in the perforator is higher than in the pedicle. The difference was statistically significant (P<0.01). There is an inversion of the gradient of blood velocity between pedicle artery and perforator artery compared to normal circulation. Furthermore, in normal circulation flow through the perforator was found smaller than that at the pedicle, whereas in perforator flaps, flow through the perforator is smaller but is a greater proportion of the flow through the pedicle and the difference is statistically significant (P<0.01). Therefore, the velocity of blood and the rate of flow reaching the skin are higher in perforator flaps than in normal circulation.  相似文献   
900.
Priori  A.  Cogiamanian  F.  Mrakic-Sposta  S. 《Neurological sciences》2006,27(4):s307-s309
Neurological Sciences - Spasticity arises from lesions involving the corticoreticulospinal system in the brain, brainstem or spinal cord. Abnormal suprasegmental influences lead to increased spinal...  相似文献   
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