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   24152篇
  免费   1296篇
  国内免费   112篇
耳鼻咽喉   393篇
儿科学   462篇
妇产科学   473篇
基础医学   3198篇
口腔科学   2554篇
临床医学   1579篇
内科学   5420篇
皮肤病学   442篇
神经病学   1945篇
特种医学   525篇
外科学   3143篇
综合类   92篇
一般理论   8篇
预防医学   2233篇
眼科学   501篇
药学   1414篇
中国医学   204篇
肿瘤学   974篇
  2023年   189篇
  2022年   529篇
  2021年   903篇
  2020年   573篇
  2019年   703篇
  2018年   858篇
  2017年   523篇
  2016年   611篇
  2015年   838篇
  2014年   1170篇
  2013年   1310篇
  2012年   1922篇
  2011年   2280篇
  2010年   1137篇
  2009年   958篇
  2008年   1686篇
  2007年   1658篇
  2006年   1486篇
  2005年   1307篇
  2004年   1113篇
  2003年   953篇
  2002年   819篇
  2001年   257篇
  2000年   229篇
  1999年   185篇
  1998年   111篇
  1997年   90篇
  1996年   74篇
  1995年   56篇
  1994年   47篇
  1993年   45篇
  1992年   85篇
  1991年   97篇
  1990年   70篇
  1989年   63篇
  1988年   45篇
  1987年   56篇
  1986年   48篇
  1985年   52篇
  1984年   44篇
  1983年   45篇
  1982年   26篇
  1981年   21篇
  1980年   25篇
  1979年   25篇
  1978年   19篇
  1977年   18篇
  1973年   18篇
  1970年   18篇
  1966年   18篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Granulomatous slack skin is an indolent T-cell lymphoma, considered to be a variant of mycosis fungoides. Clinically it is characterized by areas of redundant skin, wrinkled, inelastic, with variable erythema and infiltration besides a poikilodermic surface. A differential diagnosis unknown to most dermatologists is the giant cell tumor of soft tissue, which is an extremely rare low-grade sarcoma. The authors report a patient who had undergone extensive surgery because of a primary diagnosis of giant cell tumor of soft tissue, but which proved to be granulomatous slack skin after a second interventional procedure with confirmatory histopathology.  相似文献   
12.
Purpose:This study assessed the regeneration potential of mesenchymal stem cells (MSC) from adipose tissue associated with platelet-rich plasma (PRP) in bone regeneration.Methods:Thirty Wistar rats (Rattus norvegicus albinos) were divided into five groups (according to the grafting material and time to euthanasia): (1) autograft - 14 days (control), (2) autograft - 28 days (control), (3) MSC + PRP - 14 days, (4) MSC + PRP + papaverine - 14 days and (5) MSC + PRP + papaverine - 28 days. After euthanasia, the graft was removed and histological slides were prepared. They were assessed by a blinded pathologist using a previously published histological scale as parameter.Results:There was some degree of neoformed bone trabeculae (NBT) in 93.3% of the samples, as well as osteoblastic activity (OA). The autograft groups (14 and 28 days) had higher levels in the formation of bone trabeculae. Nonparametric data were analyzed using the Wilcoxon-Mann-Whitney test and proved not to be statistically significant at p < 0.05.Conclusions:Experimental parietal bone reconstruction, combining MSC, PRP and papaverine presented regeneration in all groups with no significant difference among them.Key words: Bone Regeneration, Platelet-Rich Plasma, Tissue Engineering, Rats  相似文献   
13.
14.
15.
16.
Diffusely adhering Escherichia coli (E. coli) strains (DAEC) represent a potential cause of diarrhoea in infants, and the detection of type three secretion system (TTSS) genes in DAEC would substantiate their pathogenic nature. In this work, four isolates of DAEC, recovered from stools of diarrhoeic children, were analysed by PCR, in order to detect the presence of TTSS genes. Primers targeted to the escC, escJ, escN and escV, some of the most conserved TTSS genes in enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC and EHEC), were used in order to verify the occurrence of homologous genes in our DAEC isolates. By this approach, we were able to characterise DNA fragments corresponding to putative escJ and escN genes in all DAEC isolates. Furthermore, DNA fragments homologous to the escC and escV genes were also amplified from all isolates. Besides the similarity found among the DAEC esc homologues with EPEC and EHEC esc genes, the nucleotide sequence analysis of the flanking regions of the amplified DNA fragments suggests that the putative DAEC esc genes are organised in the same manner as observed in EPEC and in EHEC strains. The results described here provide strong evidence for the presence of a TTSS in the DAEC strains analysed, implicating a pathogenic nature of these isolates.  相似文献   
17.
Juvenile Parkinsonism: clinical and metabolic characteristics.   总被引:1,自引:1,他引:0       下载免费PDF全文
Twenty one patients with idiopathic Parkinsonism beginning before the age of 40 years were investigated. The mean duration of the disease was 19 years. There was a good and sustained response to levodopa. Only four patients reached stages IV and V (Hoehn and Yahr). Intolerance to levodopa was observed in the more advanced stages of the disease. In the series the familial incidence of Parkinsonism (2 cases) and essential tremor (3 cases) was very low. Thyroid disorder, diabetes mellitus or macrocytic anaemia was not found in any of the cases.  相似文献   
18.
19.
Age-related bone loss has been associated with high levels of marrow adipogenesis. Estrogens (E2) are known to regulate the differentiation of marrow precursors into osteoblasts, however, their role in bone marrow adipogenesis remain unknown. E2 regulate adipocyte differentiation in subcutaneous and visceral fat through interaction with other nuclear receptors. This interaction has not been assessed in bone marrow adipocytes in vivo. In this study, we compared two groups of animals, young and old, after either oophorectomy (OVX) or oophorectomy plus E2 (OVX + E2) replacement. We found that absence of E2 was associated with higher levels of PPARγ and lower levels of Sirt1 most significantly in the old group. In addition, old mice responded better to E2 replacement in terms of reducing adipogenesis and PPARγ expression as well as increasing levels of Sirt1 expression. Our findings represent a new understanding of the role of E2 in age-related bone loss, which could be mediated through the regulation of Sirt1 expression within the bone marrow. In addition, this evidence suggests that old individuals may show a better response to E2 administration in terms of reverting the high levels of marrow fat seen in age-related bone loss.  相似文献   
20.
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