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   880篇
  免费   58篇
  国内免费   7篇
耳鼻咽喉   8篇
儿科学   32篇
妇产科学   4篇
基础医学   117篇
口腔科学   37篇
临床医学   76篇
内科学   190篇
皮肤病学   9篇
神经病学   39篇
特种医学   31篇
外科学   186篇
综合类   16篇
一般理论   1篇
预防医学   47篇
眼科学   16篇
药学   77篇
中国医学   5篇
肿瘤学   54篇
  2025年   5篇
  2024年   3篇
  2023年   11篇
  2022年   20篇
  2021年   40篇
  2020年   18篇
  2019年   29篇
  2018年   50篇
  2017年   23篇
  2016年   31篇
  2015年   31篇
  2014年   48篇
  2013年   43篇
  2012年   72篇
  2011年   93篇
  2010年   45篇
  2009年   41篇
  2008年   61篇
  2007年   49篇
  2006年   41篇
  2005年   27篇
  2004年   33篇
  2003年   25篇
  2002年   26篇
  2001年   6篇
  2000年   10篇
  1999年   8篇
  1998年   10篇
  1997年   6篇
  1996年   2篇
  1995年   3篇
  1994年   5篇
  1993年   3篇
  1992年   3篇
  1991年   8篇
  1990年   2篇
  1989年   4篇
  1988年   2篇
  1987年   2篇
  1985年   1篇
  1982年   1篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1975年   1篇
排序方式: 共有945条查询结果,搜索用时 15 毫秒
91.
Purpose  Desmoplastic infantile gangliogliomas (DIG) are rare benign intracranial neoplasms of early childhood with involvement of superficial cerebral cortex and leptomeninges. The purpose of the study was to determine the alterations in metabolite ratios occurring in the neoplasm and combine with magnetic resonance (MR) imaging features to narrow down the diagnosis. Methods  MR imaging sequences include T1- and T2-weighted sequences, fluid-attenuated inversion recovery sequences, and post-gadolinium-contrast T1-weighted imaging. Single-voxel short TE 1H MR spectroscopy was used to study the changes in metabolite ratios in the tumor. Results  Comparison of metabolite ratios between normal brain tissue and tumor-affected region showed lower N-acetyl aspartate to creatine (Cr; 1.58 vs.1.28), higher choline to Cr (0.82 vs.2.03), and no significant change in myo-inositol to Cr (0.42 vs.0.39). Conclusion  MR spectroscopy and imaging provide valuable information in the diagnosis of DIG.  相似文献   
92.
93.
Editorial     
Fibrous histiocytoma is a tumor composed of a mixture of fibroblastic and histiocytic cells. These lesions most often arise on the skin, but may rarely occur in soft deep tissues. The diagnosis of FH may be clinically difficult when the lesion is located in the deep tissues, and is frequently confirmed after local excision. The most important diagnostic necessity is the separation of this tumor from aggressive forms of fibrohistiocytic neoplasms. We present a unique case of malignant fibrous histiocytoma developing in left buccal mucosa very near to the surgical margin from which a benign fibrous histiocytoma of the mandible was excised 3 years earlier in a 31 year old female. Clinical and histopathological evidence were not sufficient to establish link between these two processes. This article aims to describe the case and discuss the findings.  相似文献   
94.
Ameloblastoma is a locally aggressive benign epithelial odontogenic tumor, while unicystic ameloblastoma is a relatively less aggressive variant. Although rare in unicystic or cystic ameloblastoma, granular cell change in ameloblastoma is a recognized phenomenon. The purpose of the present article is to report a case of cystic granular cell ameloblastoma in 34-year old female.  相似文献   
95.
Purpose  To demonstrate that polyanhydride copolymer chemistry affects the uptake and intracellular compartmentalization of nanospheres by THP-1 human monocytic cells. Methods  Polyanhydride nanospheres were prepared by an anti-solvent nanoprecipitation technique. Morphology and particle diameter were confirmed via scanning election microscopy and quasi-elastic light scattering, respectively. The effects of varying polymer chemistry on nanosphere and fluorescently labeled protein uptake by THP-1 cells were monitored by laser scanning confocal microscopy. Results  Polyanhydride nanoparticles composed of poly(sebacic anhydride) (SA), and 20:80 and 50:50 copolymers of 1,6-bis-(p-carboxyphenoxy)hexane (CPH) anhydride and SA were fabricated with similar spherical morphology and particle diameter (200 to 800 nm). Exposure of the nanospheres to THP-1 monocytes showed that poly(SA) and 20:80 CPH:SA nanospheres were readily internalized whereas 50:50 CPH:SA nanospheres had limited uptake. The chemistries also differentially enhanced the uptake of a red fluorescent protein-labeled antigen. Conclusions  Nanosphere and antigen uptake by monocytes can be directly correlated to the chemistry of the nanosphere. These results demonstrate the importance of choosing polyanhydride chemistries that facilitate enhanced interactions with antigen presenting cells that are necessary in the initiation of efficacious immune responses.  相似文献   
96.
97.
98.
Because of the spatial and temporal heterogeneities of cancers, technologies to investigate cancer cells and the consequences of their interactions with abnormal physiological environments, such as hypoxia and acidic extracellular pH, with stromal cells, and with the extracellular matrix, under controlled conditions, are valuable to gain insights into the functioning of cancers. These insights can lead to an understanding of why cancers invade and metastasize, and identify effective treatment strategies. Here we have provided an overview of the applications of MRI/MRS/MRSI to investigate intact perfused cancer cells, their metabolism and invasion, and their interactions with stromal cells and the extracellular matrix.  相似文献   
99.
100.
We describe a 5-year-old boy with Fontan physiology and a ventricular pacemaker who developed severe plastic bronchitis. Evaluation by cardiac catheterization revealed profoundly altered hemodynamics, which improved with atrial pacing. Following implantation of an atrial pacemaker, which restored atrioventricular (A-V) synchrony, the patients hemodynamics greatly improved and his plastic bronchitis resolved.  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