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   6444篇
  免费   258篇
  国内免费   80篇
耳鼻咽喉   79篇
儿科学   118篇
妇产科学   311篇
基础医学   643篇
口腔科学   206篇
临床医学   496篇
内科学   1707篇
皮肤病学   86篇
神经病学   378篇
特种医学   324篇
外科学   1179篇
综合类   25篇
一般理论   1篇
预防医学   210篇
眼科学   340篇
药学   241篇
中国医学   4篇
肿瘤学   434篇
  2024年   6篇
  2023年   69篇
  2022年   127篇
  2021年   196篇
  2020年   116篇
  2019年   175篇
  2018年   225篇
  2017年   118篇
  2016年   167篇
  2015年   164篇
  2014年   254篇
  2013年   365篇
  2012年   498篇
  2011年   586篇
  2010年   361篇
  2009年   356篇
  2008年   488篇
  2007年   548篇
  2006年   499篇
  2005年   441篇
  2004年   339篇
  2003年   260篇
  2002年   197篇
  2001年   35篇
  2000年   18篇
  1999年   15篇
  1998年   38篇
  1997年   20篇
  1996年   22篇
  1995年   18篇
  1994年   9篇
  1993年   5篇
  1992年   9篇
  1990年   2篇
  1989年   8篇
  1988年   2篇
  1987年   3篇
  1986年   1篇
  1984年   8篇
  1983年   6篇
  1982年   2篇
  1981年   2篇
  1980年   2篇
  1978年   1篇
  1977年   1篇
排序方式: 共有6782条查询结果,搜索用时 0 毫秒
51.
Pollen grains from the plant cover of a given area participate largely in the composition of aeroflora (pollen and molds) of this area. Association of allergic respiratory disorders with concentration of allergenic particles in the atmosphere is well documented, and aerobiologic studies are of great relevance. A 10-year volumetric aerobiologic study was conducted in the city of Heraklion, located in the center of the north-shore of the island of Crete, Greece. Main allergenic families and genera encountered were, in descending order of frequency Oleaceae, Quercus, Platanaceae, Cupressaceae, Pinaceae, Populus, Moraceae, and Corylaceae. Concentrations noted for most of these aeroallergens were much lower than those reported from other European regions. In parallel, an atopic population of 576 individuals, exhibiting allergic symptoms mainly of the respiratory tract were subjected to a battery of skin-prick tests. A fair degree of agreement between total pollen counts and positive skin-prick test frequencies for the families of Oleaceae, Platanaceae, and Cupressaceae was noted. On the contrary a poor degree of concordance was noted for the rest of the families and genera.  相似文献   
52.
Intercellular biomolecule transfer (ICBT) between malignant and benign cells is a major driver of tumor growth, resistance to anticancer therapies, and therapy-triggered metastatic disease. Here we characterized cholesterol 25-hydroxylase (CH25H) as a key genetic suppressor of ICBT between malignant and endothelial cells (ECs) and of ICBT-driven angiopoietin-2–dependent activation of ECs, stimulation of intratumoral angiogenesis, and tumor growth. Human CH25H was downregulated in the ECs from patients with colorectal cancer and the low levels of stromal CH25H were associated with a poor disease outcome. Knockout of endothelial CH25H stimulated angiogenesis and tumor growth in mice. Pharmacologic inhibition of ICBT by reserpine compensated for CH25H loss, elicited angiostatic effects (alone or combined with sunitinib), augmented the therapeutic effect of radio-/chemotherapy, and prevented metastatic disease induced by these regimens. We propose inhibiting ICBT to improve the overall efficacy of anticancer therapies and limit their prometastatic side effects.  相似文献   
53.
Resistance to antiviral treatment for chronic hepatitis B virus (HBV) has been associated with mutations in the HBV polymerase region. This study aimed at developing an ultrasensitive method for quantifying viral populations with all major HBV resistance-associated mutations, combining the amplification refractory mutation system real-time PCR (ARMS RT-PCR) with a molecular beacon using a LightCycler. The discriminatory ability of this method, the ARMS RT-PCR with molecular beacon assay, was 0.01 to 0.25% for the different HBV resistance-associated mutations, as determined by laboratory-synthesized wild-type (WT) and mutant (Mut) target sequences. The assay showed 100% sensitivity for the detection of mutant variants A181V, T184A, and N236T in samples from 41 chronically HBV-infected patients under antiviral therapy who had developed resistance-associated mutations detected by direct PCR Sanger sequencing. The ratio of mutant to wild-type viral populations (the Mut/WT ratio) was >1% in 38 (63.3%) of 60 samples from chronically HBV-infected nucleos(t)ide analogue-naive patients; combinations of mutations were also detected in half of these samples. The ARMS RT-PCR with molecular beacon assay achieved high sensitivity and discriminatory ability compared to the gold standard of direct PCR Sanger sequencing in identifying resistant viral populations in chronically HBV-infected patients receiving antiviral therapy. Apart from the dominant clones, other quasispecies were also quantified. In samples from chronically HBV-infected nucleos(t)ide analogue-naive patients, the assay proved to be a useful tool in detecting minor variant populations before the initiation of the treatment. These observations need further evaluation with prospective studies before they can be implemented in daily practice.  相似文献   
54.
55.
Understanding the mode of action of pathogenic bacteria through in vitro studies can provide additional insight into their infection strategies. Here we have characterized the effect of Photorhabdus luminescens and Photorhabdus asymbiotica on two distinct insect cell lines. We report that insect cell survival and metabolism as well as bacterial proliferation differ between infection with two Photorhabdus species. These findings reinforce the notion that P. luminescens and P. asymbiotica deploy diverse tactics to infect insect cells. This knowledge might lead to better appreciation of the interaction between pathogenic bacteria and different types of insect cells.  相似文献   
56.
Clinical and Experimental Medicine - The new type of coronavirus (COVID-19), SARS-CoV-2 originated from Wuhan, China and has led to a worldwide pandemic. COVID-19 is a novel emerging infectious...  相似文献   
57.
58.
59.
Intercostal hernias are rare, and usually occur following injuries of the thoracic wall. The scope of this report is to present a case of a 53-year-old obese patient that developed a transdiaphragmatic intercostal hernia. The patient presented with a palpable, sizeable, reducible mass in the right lateral thoracic wall, with evident bowel sounds in the area, 6 months after a motor-vehicle accident. On computed tomography (CT), the hernia sac contained part of the liver and part of the ascending colon. A surgical repair of the defect was performed, using a prosthetic patch. The patient''s postoperative course was uneventful and she remains recurrence free at 12 months after surgery. Intercostal hernias should be suspected following high-impact injuries of the thoracic wall, and CT scans will facilitate the diagnosis of intercostal hernia. We consider the surgical repair of the defect, with placement of a prosthetic mesh, as the treatment of choice to ensure a favorable outcome.Key words: Hernia, Transdiaphragmatic, Intercostal, Abdominal, MeshThe herniation of abdominal contents through the thoracic wall, as a result of the disruption of diaphragmatic and/or intercostal muscles, is an uncommon clinical entity.13 This condition is usually reported to occur following penetrating or blunt injuries of the thoracic wall.4 However, there are several cases that have been described to be a consequence of a coughing–spell rib fracture, usually in patients with other predisposing factors such as chronic obstructive pulmonary disease, asthma, advanced age, or osteoporosis.1,3,4The present report describes a case of a middle-aged obese patient that developed a transdiaphragmatic intercostal hernia involving the liver and the ascending colon 6 months after a traumatic incident. The underlying mechanism, the anatomical and diagnostic considerations, as well as the treatment options are also discussed.  相似文献   
60.
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