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   104760篇
  免费   8735篇
  国内免费   6123篇
耳鼻咽喉   1113篇
儿科学   1555篇
妇产科学   2305篇
基础医学   12432篇
口腔科学   1953篇
临床医学   14033篇
内科学   16612篇
皮肤病学   895篇
神经病学   5673篇
特种医学   3539篇
外国民族医学   42篇
外科学   11243篇
综合类   14794篇
现状与发展   23篇
一般理论   20篇
预防医学   6121篇
眼科学   2866篇
药学   10703篇
  56篇
中国医学   4838篇
肿瘤学   8802篇
  2024年   280篇
  2023年   1503篇
  2022年   3802篇
  2021年   4975篇
  2020年   3522篇
  2019年   3241篇
  2018年   3543篇
  2017年   2923篇
  2016年   2843篇
  2015年   4411篇
  2014年   5617篇
  2013年   5009篇
  2012年   7524篇
  2011年   8267篇
  2010年   4986篇
  2009年   3819篇
  2008年   5271篇
  2007年   5531篇
  2006年   5411篇
  2005年   5704篇
  2004年   3836篇
  2003年   3399篇
  2002年   3007篇
  2001年   2445篇
  2000年   2650篇
  1999年   2705篇
  1998年   1590篇
  1997年   1488篇
  1996年   1312篇
  1995年   1165篇
  1994年   989篇
  1993年   641篇
  1992年   999篇
  1991年   806篇
  1990年   686篇
  1989年   603篇
  1988年   594篇
  1987年   530篇
  1986年   422篇
  1985年   330篇
  1984年   208篇
  1983年   159篇
  1982年   88篇
  1981年   101篇
  1980年   83篇
  1979年   115篇
  1978年   55篇
  1977年   56篇
  1975年   44篇
  1974年   45篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
33.
OBJECTIVE: To examine the distribution of rat facial motoneurons contributing different branches under normal situation and when nerve reinnervation occurred following facial nerve axotomy. METHODS: The normal distribution of motoneurons innervated both buccal and marginal mandibular branches and its reorganization after facial nerve reinnervation was observed using retrograde labeling with fluorescein. RESULTS: Under normal situation, the motoneurons contributing buccall and marginal mandibular branches were primarily distributed in the intermedial and lateral subnucleus in facial nucleus and almost completely overlapped. The two types labeled neurons organized closely, but there were no double-labeled neurons. Although the motoneurons contributing buccall and marginal mandibular branches were primarily overlapped 4 month post-anastomosis, the number of the labeled neurons obviously decreased and the organization got more scattered. There were 10% of buccall branches, 5% of marginal mandibular motoneurons in the dorsal subnuleus, 1% of buccall and 4% of marginal mandibular in dorsal ventral and medial subnucleus. The distribution pattern of the motoneurons 6 month post-anastomosis was similar to that of 4 month post-anastomosis, but the number of the labeled neurons increased, and there were 1%-2% double-labeled neurons. CONCLUSION: The distribution pattern of motoneurons innervated both buccal and marginal mandibular branches indicates that it should exist wide-spread communicating branches, and its reorganization after facial nerve reinnervation suggests that misdirected regeneration occurs among motoneurons innervating different branches.  相似文献   
34.
本文作者改进了辣椒中辣椒素含量的测定法。即通过增设洋品空白管以消除色素的干扰;改变 Na_2CO_3溶液的浓度以缓和其操作条件及防止在低温时产生沉淀。本改良法具有简便、快速和重现性好之优点。  相似文献   
35.
36.
37.
全营养素混合液(TNA)在肠外营养的应用   总被引:2,自引:0,他引:2  
黄德骧  吴肇汉 《营养学报》1989,11(2):97-103
脂肪乳剂、葡萄糖、氨基酸、电解质、维生素及微量元素按一定程序混合配成10种全营养素混合液。在4℃14天贮存期内,10种混合液的pH和渗透压变化不大,不同混合液在不同时期的脂粒平均直径变化为0.3135±0.1012μm~0.4813±0.1893μm,94.93%脂粒的直径<0.6μm,无直径>6μm的脂粒,细菌培养阴性。74例共输全营养素混合液1,796次,无不良临床反应和异常实验室检查结果;用1周以上者大都显示氮平衡改善,用2周以上者血清转铁蛋白和白蛋白浓度可有不同程度升高。  相似文献   
38.
39.
40.
OBJECTIVES: To examine the effect of individual patient factors (age, parity, body mass index, menstrual cycle, menopause, hormone replacement therapy, bladder neck position and urethral mobility) on the appearance of Doppler flow in urethral vessels, to investigate the association between the Doppler flow parameters and intrinsic urethral function, storage and voiding, and to explore differences in the urethral vasculature between subjects with and without urodynamic stress incontinence (USI). METHODS: Over a 4-year period we prospectively performed imaging studies in 355 women, including 244 who denied any lower urinary tract symptoms within the previous 3 months (Group A) and 111 who had had lower urinary tract symptoms (Group B). Studies included morphologic assessment and Doppler flow investigation of the lower urinary tract. Vascular flow velocity and vessel density in the urethral vasculature were measured. For women in Group B, multichannel urodynamic studies were also performed. RESULTS: The urethral vasculature has five main branches of vessels. Their appearance was not affected by the menstrual cycle or menopause except for those of the anterior vaginal vessel and anterior branch of the middle urethral vessel. Other than that of the posterior urethral vessel, in which there was a correlation with parity, the resistance index (RI) was not affected by individual patient factors. However, there was a correlation between the vascular index (VI) and individual factors such as age (r = -0.336, P = 0.002), body mass index (r = -0.287, P = 0.028), menopause (r = -0.402, P < 0.001), and hormone replacement therapy (r = 0.392, P = 0.027). Only the VI and RI of the posterior urethral vessel correlated significantly with the urethral pressure profile. In subjects with lower urinary tract symptoms, the appearance of the urethral vasculature on power Doppler imaging and the corresponding RI and VI values were not correlated with objective evidence of USI. CONCLUSION: Patient factors may affect specific Doppler flow parameters of the urethral vasculature, which are related to intrinsic resting urethral closure. There is no difference in the appearance of the urethral vasculature in subjects with or without USI.  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