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   41070篇
  免费   4145篇
  国内免费   1335篇
耳鼻咽喉   291篇
儿科学   1511篇
妇产科学   480篇
基础医学   4430篇
口腔科学   770篇
临床医学   3947篇
内科学   6033篇
皮肤病学   738篇
神经病学   2222篇
特种医学   1254篇
外国民族医学   8篇
外科学   4585篇
综合类   5042篇
现状与发展   9篇
一般理论   6篇
预防医学   3385篇
眼科学   1663篇
药学   4753篇
  37篇
中国医学   2220篇
肿瘤学   3166篇
  2024年   166篇
  2023年   643篇
  2022年   1560篇
  2021年   2016篇
  2020年   1619篇
  2019年   1309篇
  2018年   1367篇
  2017年   1338篇
  2016年   1186篇
  2015年   1616篇
  2014年   1927篇
  2013年   2181篇
  2012年   2945篇
  2011年   2917篇
  2010年   2060篇
  2009年   1633篇
  2008年   2104篇
  2007年   1929篇
  2006年   1702篇
  2005年   1514篇
  2004年   1208篇
  2003年   1154篇
  2002年   1070篇
  2001年   916篇
  2000年   847篇
  1999年   710篇
  1998年   294篇
  1997年   260篇
  1996年   231篇
  1995年   219篇
  1994年   165篇
  1993年   175篇
  1992年   416篇
  1991年   415篇
  1990年   380篇
  1989年   417篇
  1988年   314篇
  1987年   323篇
  1986年   266篇
  1985年   289篇
  1984年   255篇
  1983年   226篇
  1982年   139篇
  1979年   198篇
  1978年   132篇
  1975年   146篇
  1974年   155篇
  1973年   145篇
  1972年   137篇
  1971年   150篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.

Purpose  

The aim of this study was to determine whether estrogen receptor (ER)/progesterone receptor (PR) and human epidermal growth factor receptor type 2 (HER2) statuses between primary tumors and paired liver metastatic localizations of breast carcinoma were modified by treatment or during the natural metastatic process.  相似文献   
972.
Extraosseous Ewing's sarcoma/primitive neuroectodermal tumor (ES/PNET) is an uncommon, aggressive, and malignant tumor with a poor patient outcome. Its occurrence in the lesser sac is a rare event and to the best of our knowledge, has not been previously described. The present case was clinically and radiologically misdiagnosed as a pancreatic tumor/gastrointestinal stromal tumor. Histopathology revealed a tumor with "small round cells" that were positive for CD99, confirming the diagnosis of ES/PNET. This report highlights the importance of considering Ewing's sarcoma in the differential diagnosis of intraabdominal, extraintestinal masses.  相似文献   
973.
974.
颅内原发性恶性黑色素瘤是中枢神经系统罕见肿瘤,而颅内继发性恶性黑色素瘤则是临床常见的居第3位的颅内转移瘤,恶性程度高,患者预后不良,其诊断和治疗一直是神经外科领域的难点。本文回顾分析经显微外科手术治疗的2例颅内恶性黑色素瘤患者的临床特点、影像学表现、病理学特征及预后等情况,并结合文献对其诊断和治疗策略进行阐述。  相似文献   
975.
Knowledge of the plasticity of language pathways in patients with low-grade glioma is important for neurosurgeons to achieve maximum resection while preserving neurological function. The current study sought to investigate changes in the ventral language pathways in patients with low-grade glioma located in regions likely to affect the dorsal language pathways. The results revealed no significant difference in fractional anisotropy values in the arcuate fasciculus between groups or between hemispheres. However, fractional anisotropy and lateralization index values in the left inferior longitudinal fasciculus and lateralization index values in the left inferior fronto-occpital fasciculus were higher in patients than in healthy subjects. These results indicate plasticity of language pathways in patients with low-grade glioma. The ventral language pathways may perform more functions in patients than in healthy subjects. As such, it is important to protect the ventral language pathways intraoperatively.  相似文献   
976.
Neurotrophin-3 (NT-3) can promote the repair of central nervous system and retinal damage. In previous reports, NT-3 has been expressed by viral vectors. However, plasmid vectors have a safer profile compared with viral vectors in clinical studies. This study recombined amplified human retinal NT-3 with a eukaryotic expression plasmid containing green fluorescent protein (GFP) to construct an NT-3 expression plasmid, pEGFP-N1-NT-3. The transfection efficiency 48 hours after pEGFP-N1-NT-3 transfection to 293T cells was 50.06 ± 2.78%. Abundant NT-3-GFP was expressed in 293T cells as observed by fluorescence microscopy, suggesting the construct pEGFP-N1-NT-3 effectively expressed and secreted NT-3-GFP. Secretory vesicles containing NT-3-GFP were observed in a constant location in cells by laser scan confocal microscopy, indicating the expression and secretion processes of NT-3 in eukaryotic cells were in accordance with the physical synthesis processes of secreted proteins. Western blot assay showed that pro-NT-3-GFP had a molecular weight of 56 kDa, further confirming NT-3-GFP expression. At 48 hours after transfection, the concentration of NT-3 in culture medium was 22.3 ng/mL, suggesting NT-3 produced by pEGFP-N1-NT-3 was efficiently secreted. This study constructed a human retinal-derived NT-3 eukaryotic expression plasmid that efficiently expressed and secreted NT-3.  相似文献   
977.
C677T polymorphism in the methylenetetrahydrofolate reductase (MTHFR) gene is a risk factor for stroke, suggesting that widespread detection could help to prevent stroke. DNA from 70 stroke pa- tients and 70 healthy controls was extracted from saliva using a magnetic nanoparticles-based method and from blood using conventional methods. Real-time PCR results revealed that the C677T polymorphism was genotyped by PCR using DNA extracted from both saliva and blood samples. The genotype results were confirmed by gene sequencing, and results for saliva and blood samples were consistent. The mutation TT genotype frequency was significantly higher in the stroke group than in controls. Homocysteine levels were significantly higher than controls in both TT genotype groups. Therefore, this noninvasive magnetic nanoparticles-based method using saliva samples could be used to screen for the MTHFR C677T polymorphism in target populations.  相似文献   
978.
979.
980.
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