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   1347295篇
  免费   112805篇
  国内免费   6399篇
耳鼻咽喉   16825篇
儿科学   43136篇
妇产科学   36798篇
基础医学   185461篇
口腔科学   36435篇
临床医学   121147篇
内科学   279265篇
皮肤病学   32241篇
神经病学   111232篇
特种医学   56937篇
外国民族医学   274篇
外科学   211350篇
综合类   31569篇
现状与发展   2篇
一般理论   414篇
预防医学   107283篇
眼科学   28155篇
药学   94607篇
  5篇
中国医学   2299篇
肿瘤学   71064篇
  2018年   13537篇
  2017年   10743篇
  2016年   12948篇
  2015年   14393篇
  2014年   20135篇
  2013年   30034篇
  2012年   36850篇
  2011年   39833篇
  2010年   24773篇
  2009年   24029篇
  2008年   37014篇
  2007年   39571篇
  2006年   40683篇
  2005年   39124篇
  2004年   37281篇
  2003年   36379篇
  2002年   34318篇
  2001年   66271篇
  2000年   68203篇
  1999年   56752篇
  1998年   16769篇
  1997年   15057篇
  1996年   16033篇
  1995年   16266篇
  1994年   15116篇
  1993年   14166篇
  1992年   47113篇
  1991年   45763篇
  1990年   43987篇
  1989年   41832篇
  1988年   38778篇
  1987年   38093篇
  1986年   35872篇
  1985年   34662篇
  1984年   26373篇
  1983年   22125篇
  1982年   13865篇
  1981年   12470篇
  1980年   11741篇
  1979年   23562篇
  1978年   17097篇
  1977年   14396篇
  1976年   13196篇
  1975年   13743篇
  1974年   16109篇
  1973年   15411篇
  1972年   14182篇
  1971年   13049篇
  1970年   11887篇
  1969年   11110篇
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
91.
Malignant tumors of the bones   总被引:2,自引:0,他引:2  
  相似文献   
92.
93.
94.
The Dundee Memory Clinic was established in 1991. This paper reviews the diagnosis of the first 150 attenders and compares the findings with those of other memory clinics.  相似文献   
95.
96.
Choristomas, masses of normal tissues in aberrant locations, contain smooth muscle fibers and fibrous tissues. We describe the MR imaging features of two choristomas located in the internal auditory canals and arising from the facial and vestibulocochlear nerves. Both lesions enhanced with contrast material. In one case, enhancement was seen in the geniculate ganglion and greater superficial petrosal nerve. In the other, a medial component enhanced less than the lateral component did.  相似文献   
97.
The ability of three Porphyromonas spp., seven Prevotella spp., seven Fusobacterium spp. and two related Bacteroides spp. (B. levii and B. macacae) to degrade an extensive range of synthetic endo-, amino- and diamino peptidase substrates linked to the fluorescent leaving group 7-amido-4-methylcoumarin (NHMec) was investigated. Many more species than was previously recognized exhibited peptidase activities, albeit at lower levels than those already described for Porphyromonas gingivalis. Detection of chymotrypsin-like activity was dependent on which of three NHMec-linked substrates was used, but all species exhibited degradative activity with at least one of these substrates. Elastase-like activity was detected in all species though not all species reacted with each of the elastase substrates. Glycylprolyl peptidase activity was detected in all of the species tested with the exception of F. mortiferum, F. gonidiaformans, F. naviforme and F. necrophorum. While the detection of peptidase activities does not appear to be useful for the differentiation of species within the genera Bacteroides and Prevotella, its ability to differentiate species of the genus Porphyromonas or Fosobacterium further investigation.  相似文献   
98.
The value of ultrasound in the diagnosis of a large rapidly growing thyroid mass was assessed in a study of 42 patients with a large (> 3 cm) rapidly growing (< two months) solitary mass. Haemorrhage into a thyroid nodule was present in 31 patients and thyroid malignancy in 11. Ultrasound of haemorrhage into a thyroid nodule revealed a large cystic mass in all 31 patients containing internal debris (22), septations (three), or a combination of both (six). The malignant causes of a large rapidly growing mass were lymphoma (two), anaplastic carcinoma (four) and metastasis (five). Ultrasound of these thyroid malignancies revealed a mass with a smooth, well-defined margin and strikingly low homogeneous echogenicity in all cases. Patients with thyroid metastases had evidence of widespread metastatic disease elsewhere. Lymphoma was differentiated from anaplastic carcinoma on fine-needle aspiration cytology or surgical biopsy. Ultrasound was of value in differentiating between a benign haemorrhagic nodule and a malignant tumour. The various malignant tumours had similar appearances, however, and could not be distinguished on ultrasound.  相似文献   
99.
100.
Summary GM1- and GM2-gangliosides were isolated from brain and radio-labelled. The labelled moieties were localized by hydrolysis with lysosomal enzymes, followed by thin-layer chromatography of the products. High-resolution loading tests with labelled gangliosides were developed and found to differentiate infantile and juvenile forms of GM1- and GM2-gangliosidoses as well as the identification of B, O and AB types of GM2-gangliosidosis.  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