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   620096篇
  免费   56676篇
  国内免费   41835篇
耳鼻咽喉   5214篇
儿科学   7521篇
妇产科学   8204篇
基础医学   70759篇
口腔科学   10513篇
临床医学   86857篇
内科学   87396篇
皮肤病学   6403篇
神经病学   31812篇
特种医学   22877篇
外国民族医学   368篇
外科学   58639篇
综合类   108313篇
现状与发展   130篇
一般理论   49篇
预防医学   42691篇
眼科学   17850篇
药学   65625篇
  653篇
中国医学   37822篇
肿瘤学   48911篇
  2024年   1913篇
  2023年   8616篇
  2022年   22716篇
  2021年   28858篇
  2020年   22187篇
  2019年   18836篇
  2018年   19946篇
  2017年   18582篇
  2016年   17245篇
  2015年   26586篇
  2014年   33331篇
  2013年   30167篇
  2012年   44862篇
  2011年   50819篇
  2010年   33429篇
  2009年   26938篇
  2008年   34528篇
  2007年   34531篇
  2006年   33738篇
  2005年   32732篇
  2004年   21417篇
  2003年   20203篇
  2002年   17084篇
  2001年   15030篇
  2000年   15458篇
  1999年   16100篇
  1998年   9866篇
  1997年   9717篇
  1996年   7614篇
  1995年   7083篇
  1994年   5834篇
  1993年   3850篇
  1992年   4914篇
  1991年   4256篇
  1990年   3674篇
  1989年   3221篇
  1988年   2663篇
  1987年   2329篇
  1986年   1927篇
  1985年   1505篇
  1984年   859篇
  1983年   617篇
  1982年   364篇
  1981年   378篇
  1980年   294篇
  1979年   363篇
  1978年   153篇
  1977年   141篇
  1974年   144篇
  1973年   119篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
<正>第5章术前辅助措施在腹疝修补术中的作用通过Medline、PubMed、Cochrane Library以及相关期刊和参考文献进行了系统的文献检索,证据结论:(1)在腹壁疝修补术之前使用A型肉毒素(botulinum toxin type A,BTA)与阿片类镇痛的使用显著减少疼痛。证据级别:3级。(2)(1)应用BTA可使腹壁疝直径减小,腹壁外侧肌厚度显著减少,腹壁外侧肌显著延长。在大多数腹疝患者中,单独  相似文献   
132.
PurposeWe previously demonstrated that the functional inactivation of DAL-1 and TOB1 promotes an aggressive phenotype in gastric cancer cells, but the links between both genes and the survival of patients with gastric cancer are unknown. Here, we investigated the correlations of the expression levels of DAL-1 and TOB1 with the progression of gastric cancer.MethodsA total of 270 patients who underwent resectable gastrectomy were included. The expression of DAL-1 and TOB1 was detected by immunohistochemistry.ResultsLow expression of DAL-1 in cancer tissue was significantly associated with tumor site (p < 0.05), histological grade (p < 0.01), depth of invasion (p < 0.05), lymph node metastasis status (p < 0.05), Lauren classification (p < 0.001), and clinical stage (p < 0.01). A lower level of TOB1 was observed in gastric cancer patients with diffuse type disease compared to patients with either intestinal or mixed type disease (p < 0.001). Additionally, Spearman’s correlation analysis revealed that decreased expression of DAL-1 was positively correlated with low TOB1 expression (r=0.304, p < 0.001). The survival analysis showed that low levels of DAL-1 and TOB1 were significantly associated with poor survival of gastric cancer patients (p <0.001 and p < 0.05, respectively).ConclusionThe downregulation of DAL-1 and TOB1 expression is associated with shorter survival of gastric cancer patients. Hence, DAL-1 and TOB1 may be considered potential novel markers for predicting the outcomes of patients with gastric cancer.  相似文献   
133.
1. To investigate Genkwa Flos hepatotoxicity, a cell metabolomics strategy combined with serum pharmacology was performed on human HL-7702 liver cells in this study.

2. Firstly, cell viability and biochemical indicators were determined and the cell morphology was observed to confirm the cell injury and develop a cell hepatotoxicity model. Then, with the help of cell metabolomics based on UPLC-MS, the Genkwa Flos group samples were completely separated from the blank group samples in the score plots and seven upregulated as well as two down-regulated putative biomarkers in the loading plot were identified and confirmed. Besides, two signal molecules and four enzymes involved in biosynthesis pathway of lysophosphatidylcholine and the sphingosine kinase/sphingosine-1-phosphate pathway were determined to investigate the relationship between Genkwa Flos hepatotoxicity and these two classic pathways. Finally, the metabolic pathways related to specific biomarkers and two classic metabolic pathways were analyzed to explain the possible mechanism of Genkwa Flos hepatotoxicity.

3. Based on the results, lipid peroxidation and oxidative stress, phospholipase A2/lysophosphatidylcholine pathway, the disturbance of sphingosine-1-phosphate metabolic profile centered on sphingosine kinase/sphingosine-1-phosphate pathway and fatty acid metabolism might be critical participators in the progression of liver injury induced by Genkwa Flos.  相似文献   

134.
135.
Programmed death ligand 1(PD-L1) mediated immune escape play important roles in the development of cancer. The gene polymorphism of PD-L1, in particular rs4143815 C?>?G, has been associated with the cancer risks, but with conflicting results. Therefore, this meta-analysis was aimed to assess the association between rs4143815 C?>?G and cancer susceptibility. A systematic literature search was performed to select the studies and the pooled odds ratio (OR) with 95% confidence interval (CI) was used to evaluate the strength of association. Eleven eligible studies containing 3711 cases and 3704 controls were enrolled in the meta-analysis. The results suggested that there is a strong association between rs4143815 C?>?G and the cancer risks (G vs. C: OR?=?1.386, 95% CI: 1.132–1.696, p?=?0.002; GG vs. CG?+?CC: OR?=?1.843 95% CI: 1.300–2.613, p?=?0.002; GG?+?CG vs. CC: OR?=?1.280, 95% CI: 1.040–1.576, p?=?0.020). Subgroup analysis based on cancer type suggested that PD-L1 rs4143815 C?>?G might increase the susceptibility to gastric cancer (G vs. C: OR?=?1.842, 95% CI: 1.403–2.418, p?<?0.001) and bladder cancer (G vs. C: OR?=?2.015, 95% CI: 1.556–2.608, p?<?0.001), and genotype GG carriers of PD-L1 rs4143815 C?>?G might have higher risks of HCC (GG vs. CG?+?CC: OR?=?2.226 95% CI: 1.562–3.172, p?<?0.001). PD-L1 rs4143815 C?>?G might confer an increased cancer risk, indicating this SNP may contribute to the pathogenesis of cancer and might be used as a potential biomarker to predict the susceptibility to cancer.  相似文献   
136.
137.
138.
目的采用图像融合技术获得T2WI与T2WI-FS的融合图像,评估其在肛瘘及肛周结构显示中的优势。 方法2016年6月至2018年6月,前瞻性选择中山大学附属第一医院29例肛瘘患者进行肛管磁共振(MR)检查,采用图像融合技术获取T2WI与T2WI-FS的融合图像T2WI-Fusion,利用Fisher score算法计算瘘管及肛门括约肌的组织间分辨力Fisher值、脂肪与肛门括约肌间的Fisher值,评估融合图像中瘘管及肛周结构的显示情况。采用改进的双刺激连续质量量表(DSCQS)对T2WI-FS、T2WI、增强3D-VIBE和T2WI-Fusion序列图像进行主观图像质量评价。 结果29例患者均成功获得T2WI与T2WI-FS的融合图像T2WI-Fusion。T2WI-Fusion、T2WI瘘管与括约肌间Fisher均值分别为6.46、3.31,T2WI-Fusion图像对瘘管的显示优于T2WI序列图像(P<0.001)。T2WI-Fusion、T2WI-FS脂肪与括约肌间Fisher均值分别为10.61、2.45,T2WI-Fusion图像对括约肌的显示优于T2WI-FS序列图像(P<0.001)。T2WI-Fusion对瘘管与括约肌的图像质量评价总评分均高于T2WI-FS、T2WI、增强3D-VIBE序列(P<0.001)。 结论MRI图像融合技术同时具备T2WI及T2WI-FS的优势,无需增加扫描序列及扫描时间,且操作简单,花费时间短,显著提高病变及肛周解剖结构的对比度和图像质量。  相似文献   
139.
140.
First described in 1955 in New Jersey, epizootic haemorrhagic disease (EHD) causes a severe clinical disease in wild and domestic ruminants worldwide. Epizootic haemorrhagic disease outbreaks occur in deer populations each year from summer to late autumn. The etiological agent is EHD virus (EHDV) which is a double‐stranded segmented icosahedral RNA virus. EHD virus utilizes point mutations and reassortment strategies to maintain viral fitness during infection. In 2018, EHDV serotype 2 was predominantly detected in deer in Illinois. Whole genome sequencing was conducted for two 2018 EHDV2 isolates (IL41747 and IL42218) and the sequence analyses indicated that IL42218 was a reassortant between different serotypes whereas IL41747 was a genetically stable strain. Our data suggest that multiple strains contribute to outbreaks each year.  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