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   89715篇
  免费   8555篇
  国内免费   2235篇
耳鼻咽喉   1125篇
儿科学   1286篇
妇产科学   667篇
基础医学   5851篇
口腔科学   1188篇
临床医学   16717篇
内科学   11558篇
皮肤病学   538篇
神经病学   9639篇
特种医学   23012篇
外国民族医学   20篇
外科学   7237篇
综合类   9249篇
现状与发展   1篇
预防医学   2376篇
眼科学   1356篇
药学   3274篇
  71篇
中国医学   741篇
肿瘤学   4599篇
  2024年   261篇
  2023年   1559篇
  2022年   3107篇
  2021年   4195篇
  2020年   3868篇
  2019年   3670篇
  2018年   3518篇
  2017年   3780篇
  2016年   4049篇
  2015年   3915篇
  2014年   6626篇
  2013年   5938篇
  2012年   5464篇
  2011年   5922篇
  2010年   4810篇
  2009年   4981篇
  2008年   4890篇
  2007年   4621篇
  2006年   4068篇
  2005年   3516篇
  2004年   2932篇
  2003年   2257篇
  2002年   1818篇
  2001年   1706篇
  2000年   1404篇
  1999年   1091篇
  1998年   1111篇
  1997年   1006篇
  1996年   831篇
  1995年   742篇
  1994年   598篇
  1993年   489篇
  1992年   393篇
  1991年   306篇
  1990年   242篇
  1989年   168篇
  1988年   148篇
  1987年   136篇
  1986年   77篇
  1985年   71篇
  1984年   53篇
  1983年   38篇
  1982年   32篇
  1981年   32篇
  1980年   22篇
  1979年   13篇
  1978年   7篇
  1977年   9篇
  1976年   5篇
  1973年   3篇
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
41.
42.
43.
44.
Preeclampsia is a disease with a significant incidence worldwide that is directly associated with 15% of maternal deaths. This is usually characterized by the presence of hypertension and proteinuria, which manifests itself from the middle of pregnancy. MicroRNAs are single-stranded RNA molecules that act primarily by degrading transcribed messenger RNA or inhibiting microRNA translation. Placental microRNAs play a role in the growth and function of the placenta, their potential use as diagnostic biomarkers is considered feasible due to the ability to enter the maternal circulation and be detectable in maternal plasma.  相似文献   
45.
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   
46.
Zygomatic implant treatment is widely applied for severe maxillary atrophy to help rehabilitate the maxillary dentition. This retrospective study was performed to evaluate the actual radiographic bone–implant contact (rBIC) lengths of zygomatic implants. The records of 28 patients who underwent zygomatic implant surgery and subsequent follow-up examinations between August 2013 and September 2018 in the Department of Oral and Maxillofacial Surgery, Taipei Tzu Chi Hospital were reviewed. The surgeries were performed by a single surgeon using the same treatment protocol. All patients had a computed tomography scan at 1 year after the surgery. Using three-dimensional imaging software, an investigator measured the rBIC lengths of 66 implants and documented their clinical status. The implant survival rate was 100%. The mean rBIC length was significantly longer in male patients than in female patients (20.80 ± 5.88 mm versus 17.79 ± 6.34 mm; P = 0.028). The mean rBIC length of double zygomatic implants was significantly longer when compared to that of single implants (21.11 ± 6.23 mm versus 17.75 ± 5.85 mm; P = 0.027). This article is novel in reporting the exact rBIC lengths of zygomatic implants in a clinical setting. The results showed that zygomatic implants are a viable treatment modality for full-mouth rehabilitation.  相似文献   
47.
48.
49.
50.
《Journal of thoracic oncology》2021,16(10):1694-1704
IntroductionIn patients with NSCLC, the prognostic significance of the tumor microenvironment (TME) immune composition has been revealed using single- or dual-marker staining on sequential tissue sections. Although these studies reveal that relative abundance and localization of immune cells are important parameters, deeper analyses of the NSCLC TME are necessary to refine the potential application of these findings to clinical care. Currently, the complex spatial relationships between cells of the NSCLC TME and potential drivers contributing to its immunologic composition remain unknown.MethodsWe used multispectral quantitative imaging on the lung adenocarcinoma TME in 153 patients with resected tumors. On a single slide per patient, we evaluated the TME with markers for CD3, CD8, CD14, CD19, major histocompatibility complex II (MHCII), cytokeratin, and 4′,6-diamidino-2-phenylindole (DAPI). Image analysis, including tissue segmentation, phenotyping, and spatial localization, was performed.ResultsSpecimens wherein greater than or equal to 5% of lung cancer cells expressed MHCII (MHCIIhi TME) had increased levels of CD4+ and CD8+ T cells and CD14+ cell infiltration. In the MHCIIhi TME, the immune infiltrate was closer to cancer cells and expressed an activated phenotype. Morphologic image analysis revealed cancer cells in the MHCIIhi TME more frequently interfaced with CD4+ and CD8+ T cells. Patients with an MHCIIhi TME experienced improved overall survival (p = 0.046).ConclusionsLung cancer cell-specific expression of MHCII associates with levels of immune cell infiltration, spatial localization, and activation status within the TME. This suggests that cancer cell-specific expression of MHCII may represent a biomarker for the immune system’s recognition and activation against the tumor.  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