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   264178篇
  免费   24559篇
  国内免费   20588篇
耳鼻咽喉   2019篇
儿科学   2341篇
妇产科学   3010篇
基础医学   32700篇
口腔科学   4314篇
临床医学   37933篇
内科学   38642篇
皮肤病学   2434篇
神经病学   14897篇
特种医学   9681篇
外国民族医学   199篇
外科学   25141篇
综合类   44093篇
现状与发展   74篇
一般理论   27篇
预防医学   15901篇
眼科学   8183篇
药学   28229篇
  299篇
中国医学   15603篇
肿瘤学   23605篇
  2024年   937篇
  2023年   4374篇
  2022年   11347篇
  2021年   14081篇
  2020年   10642篇
  2019年   9301篇
  2018年   9675篇
  2017年   8523篇
  2016年   8106篇
  2015年   12197篇
  2014年   14963篇
  2013年   12548篇
  2012年   18738篇
  2011年   21551篇
  2010年   13058篇
  2009年   10102篇
  2008年   13353篇
  2007年   13373篇
  2006年   13607篇
  2005年   13861篇
  2004年   8229篇
  2003年   7621篇
  2002年   6382篇
  2001年   5701篇
  2000年   6427篇
  1999年   7194篇
  1998年   4789篇
  1997年   4815篇
  1996年   3730篇
  1995年   3553篇
  1994年   2936篇
  1993年   2000篇
  1992年   2220篇
  1991年   1853篇
  1990年   1581篇
  1989年   1347篇
  1988年   1155篇
  1987年   1013篇
  1986年   769篇
  1985年   617篇
  1984年   352篇
  1983年   222篇
  1982年   133篇
  1981年   129篇
  1980年   91篇
  1979年   94篇
  1978年   4篇
  1977年   5篇
  1976年   6篇
  1968年   3篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
M J Zhang 《中华外科杂志》1989,27(6):321-2, 380
The anteversion angle of femoral neck in 40 children, aged 18 months to 14 years (4.6 years on average), with congenital dislocation of hip was measured pre-operatively on X-ray films according to the way of Dr. Hu's method, and from the proximal femur exposed during operation. The mean value of them was 64.6 degrees and 44 degrees respectively, being statistically significant (P less than 0.01). The method of direct measurement of the anteversion angle during operation was described. The factors affecting the diversity of the measured angle value with different methods were discussed. It seems that the calculation formula used in Hu's method should somehow be corrected and a revision is put forward.  相似文献   
42.
43.
44.
PURPOSE: Perineural invasion is a frequent occurrence in salivary adenoid cystic carcinoma (ACC) and may prevent complete surgical resection. Studies have indicated that nerve growth factor (NGF) and its high-affinity receptor tyrosine kinase A (TrkA) may play a role in perineural invasion in several malignancies in which perineural invasion is observed. The present study was conducted to investigate the expression of NGF and TrkA in salivary ACC and to examine the effects of NGF on adhesion, migration and invasion capacities of a salivary ACC cell line (SACC-83) in vitro. PATIENTS AND METHODS: Expression of NGF and TrkA was explored using immunohistochemistry in paraffin-embedded tissues of 32 cases of salivary ACC. The effects of NGF on in vitro adhesion, migration, and invasion capacities of the SACC-83 cell line were examined using an MTT assay and a modified Boyden chamber assay respectively. RESULTS: In ACC specimens, 31 (96.9%) and 32 (100%) tumors showed immunoreactivity for NGF and TrkA respectively. Significant correlations were found between NGF/TrkA expression levels and perineural invasion (P < .05). In cell adhesion assay, the percent adherences of SACC-83 cells co-cultured with 25 ng/ml NGF at 1.5 hours and 5, 25 ng/ml NGF at 6 hours were significantly higher than that co-cultured with 0 ng/ml NGF (P < .05). However, high concentration of NGF (500 ng/ml) resulted in a significant inhibition of invasion (P < .05). CONCLUSION: Overexpression of NGF and TrkA in human salivary ACC tissues may constitute a reason for perineural invasion in salivary ACC.  相似文献   
45.
胸部类癌   总被引:2,自引:0,他引:2  
本文报道了31例胸部类癌,其中胸腺类癌14例,支气管类癌17例,伴有异位ACTH综合征者17例。12例患者发生转移(39%),24例行原发肿瘤全部或部分切除,术后放疗或化疗或两者均有者17例,4例仅行探查并取活检,28例经手术及病理证实。  相似文献   
46.
A new axial skin flap based on the middle cutaneous branch of the medial plantar artery was evaluated in 33 fresh cadaver legs. The vascular pedicle of the skin flap is based on the middle cutaneous artery, its venae comitantes, and segments of the great saphenous vein, if necessary. The middle cutaneous artery is the largest cutaneous branch, arising from the medial plantar artery 2.5 cm distal to its origin. The diameter of its origin is 1.2 mm, and its pedicle is 2 cm long. The midline of the flap runs from the first web space to the heel tip. The upper and lower borders of the flap are 3 to 4 cm on either side of this line. The upper border is medial to the extensor hallucis tendon, and the lower border is medial to the abductor hallucis. Distally, the border begins 2 cm proximal to the metatarsalphalangeal joint; proximally, the border is at the middle of the medial malleolus. The flap diameter can be up to 8 × 12 cm. The middle cutaneous branch of the medial plantar artery was found in all cadaver specimens, except for one with a common trunk. The new flap design leaves the major blood supply to the foot and the plantar aponeurosis intact. It is easy to harvest and may be used either as an island flap or free flap. © 1995 Wiley-Liss, Inc.  相似文献   
47.
48.
49.
神经肽Y(NPY)是广泛分布于中枢神经系统和外周神经各部位的神经肽类物质。本实验观察NPY在体外对几种免疫细胞活性的直接作用。结果表明,NPY对小鼠T淋巴细胞丝裂原反应性和NK细胞的杀伤活性均无明显影响(P>0.05),对巨噬细胞分泌溶菌酶有明显抑制作用(P<0.05);而对B淋巴细胞丝裂原反应性则有明显的促进作用(P<0.05)。上述结果提示,NPY对部分免疫细胞功能的影响因细胞种类而异。  相似文献   
50.
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