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   2784篇
  免费   232篇
  国内免费   201篇
耳鼻咽喉   58篇
儿科学   18篇
妇产科学   92篇
基础医学   262篇
口腔科学   18篇
临床医学   437篇
内科学   322篇
皮肤病学   55篇
神经病学   157篇
特种医学   40篇
外科学   246篇
综合类   725篇
现状与发展   1篇
预防医学   150篇
眼科学   175篇
药学   173篇
  3篇
中国医学   49篇
肿瘤学   236篇
  2024年   1篇
  2023年   89篇
  2022年   209篇
  2021年   163篇
  2020年   185篇
  2019年   162篇
  2018年   134篇
  2017年   112篇
  2016年   123篇
  2015年   133篇
  2014年   175篇
  2013年   162篇
  2012年   203篇
  2011年   221篇
  2010年   192篇
  2009年   162篇
  2008年   121篇
  2007年   178篇
  2006年   162篇
  2005年   136篇
  2004年   77篇
  2003年   45篇
  2002年   22篇
  2001年   16篇
  2000年   4篇
  1999年   6篇
  1998年   9篇
  1997年   10篇
  1996年   2篇
  1995年   1篇
  1990年   1篇
  1989年   1篇
排序方式: 共有3217条查询结果,搜索用时 15 毫秒
1.
BackgroundThe American Joint Committee on Cancer (AJCC) made improvements for staging pancreatic neuroendocrine tumors (pNETs) in its 8th Edition; however, multicenter studies were not included.MethodsWe collected multicenter datasets (n = 1,086, between 2004 and 2018) to validate the value of AJCC 8 and other coexisting staging systems through univariate and multivariate analysis for well-differentiated (G1/G2) pNETs.ResultsCompared to other coexisting staging systems, AJCC 7 only included 12 (1.1%) patients with stage III tumors. Patients with European Neuroendocrine Tumor Society (ENETS) stage IIB disease had a higher risk of death than patients with stage IIIA (hazard ratio [HR]: 4.376 vs. 4.322). For the modified ENETS staging system, patients with stage IIB disease had a higher risk of death than patients with stage III (HR: 6.078 vs. 5.341). According to AJCC 8, the proportions of patients with stage I, II, III, and IV were 25.7%, 40.3%, 23.6%, and 10.4%, respectively. As the stage advanced, the median survival time decreased (NA, 144.7, 100.8, 72.0 months, respectively), and the risk of death increased (HR: II = 3.145, III = 5.925, and IV = 8.762).ConclusionThese findings suggest that AJCC 8 had a more reasonable proportional distribution and the risk of death was better correlated with disease stage.  相似文献   
2.
通过对大数据深度学习,近年人工智能技术已逐渐渗透到医学各个领域,实现一定程度应用。虽然耳鼻咽喉头颈外科专业近几年发表相关文献数量急剧增长,但大部分临床医生对于人工智能的研究还比较陌生。介绍人工智能的基本原理,列举、分析其在耳鼻喉科的主要研究情况,探讨目前人工智能技术实际应用的局限,展望未来人工智能技术在耳鼻喉科可能的应用。  相似文献   
3.
4.
Cadmium is a toxic metal that can damage the brain and other organs. This study aimed to explore the protective effects of Potentilla anserine L. polysaccharide (PAP) against CdCl2-induced neurotoxicity in N2a and SH-SY5Y cells and in the cerebral cortex of BALB/c mice. In addition, we aimed to identify the potential mechanisms underlying these protective effects. Relative to CdCl2 treatment alone, pretreatment with PAP prevented the reduction in cell viability evoked by CdCl2, decreased rates of apoptosis, promoted calcium homeostasis, decreased ROS accumulation, increased mitochondrial membrane potential, inhibited cytochrome C and AIF release, and prevented the cleavage of caspase-3 and PARP. In addition, PAP significantly decreased the CdCl2-induced phosphorylation of CaMKII, Akt, and mTOR. In conclusion, PAP represents a potential therapeutic agent for the treatment of Cd-induced neurotoxicity, functioning in part via attenuating the activation of the mitochondrial apoptosis pathway and the Ca2+-CaMKII-dependent Akt/mTOR pathway.  相似文献   
5.
6.
7.
宫颈疾病包括宫颈炎症、宫颈鳞状上皮内病变及宫颈癌,近年研究发现阴道微生物菌群产生的细胞因子及局部免疫系统与宫颈疾病的发生、发展有关。正常女性的阴道微生态环境由多种微生物构成,其中乳杆菌对维持阴道微生态平衡发挥着重要作用。宫颈癌在女性恶性肿瘤中发生率位居第一,其发生与人乳头瘤病毒(HPV)持续感染密切相关,但并非所有感染HPV者均患宫颈癌,其病因为多因素综合作用。因乳杆菌变化导致的阴道疾病与HPV感染相互作用,共同参与宫颈疾病的发生、进展,系统有效的阴道微生态环境检测对及时调节阴道微生态平衡非常重要。阴道微生物菌群与宫颈疾病之间的关系成为许多学者的研究热点,综述阴道微生态与宫颈疾病发生、发展的相关性,为宫颈疾病尤其是宫颈癌的预防、治疗及预后提供理论依据。  相似文献   
8.
The association of bone with the metabolic syndrome and its features, visceral fat accumulation or insulin resistance, remains unclear. We determined visceral and subcutaneous fat areas (V and S) by computed tomography on 187 men (28–83 years) and 125 postmenopausal women (46–82 years) with type 2 diabetes. Men whose V was 100 cm2 or more had significantly lower urinary N-terminal cross-linked telopeptide of type-I collagen (p = 0.005), higher femoral neck bone mineral density (FN-BMD) (p = 0.004), and lower prevalence of vertebral fractures (VFs) (p = 0.04) than controls. Fat mass, V, S, and lean body mass positively correlated with FN-BMD in men and with lumbar (L) and FN-BMD in women. When adjusted for weight, these correlations became negative. Urinary C-peptide positively correlated with FN-BMD in both genders. Multivariate logistic regression analysis adjusted for age, height, weight, L-BMD, duration of diabetes, and diabetes therapies identified V in men and urinary C-peptide in women as factors inversely associated with the presence of VFs [odds ratio (OR) = 0.61 per SD increase, p = 0.04, and OR = 0.32, p = 0.01, respectively]. These findings suggest that, of the components of the metabolic syndrome, body fat in gravity and hyperinsulinemia could increase FN-BMD in diabetic subjects. Visceral fat in men and hyperinsulinemia in women may protect against VFs independent of weight, L-BMD, diabetes duration, or therapies.  相似文献   
9.
目的 探讨血管紧张素Ⅱ(AngⅡ)1型受体拮抗剂(ARB)洛沙坦对代谢综合征(MS)肾组织环氧化酶2(COX-2)表达的影响及其机制。 方法 把7周大的MS模型肥胖Zucker大鼠随机分成洛沙坦处理组和未处理组,以瘦Zucker大鼠为对照组,连续给药4个月后观察肾组织内COX-2的表达。另外,用AngⅡ刺激6 h的系膜细胞和用从微型渗透泵灌注AngⅡ 5 d的C57BL/6小鼠肾脏提取的肾皮质,观察COX-2的表达。采用RT-PCR和Western印迹法分别检测COX-2 mRNA和蛋白的表达。 结果 洛沙坦可阻止肥胖Zucker大鼠肾组织内COX-2表达增加。AngⅡ直接刺激可以诱导系膜细胞和肾组织内COX-2表达增加。 结论 AngⅡ可以调控MS肾组织内COX-2表达增加。ARB可以通过抑制COX-2的表达保护MS肾脏,这对应用非COX-2抑制剂来保护MS肾脏具有重要的意义。  相似文献   
10.
OBJECTIVES: We investigated whether the Na+-H+ exchange inhibitor, HOE642 (Hoe), and/or the Na channel blocker, mexiletine (Mex), enhance a cardioprotective effect on St. Thomas' Hospital cardioplegic solution (STS) to clarify the mechanism by which intracellular Na+ is accumulated after cardioplegic arrest. MATERIALS AND METHODS: Isolated working rat hearts were perfused with Krebs-Henseleit bicarbonate buffer (KHBB). The hearts were then arrested with STS and subjected to normothermic global ischemia (30 min). This was followed by Langendorff reperfusion (15 min) and then a working reperfusion (20 min). In study A, we added Hoe (5, 10, and 20 microM), Mex (70 microM), or a combination of Hoe (20 microM) and Mex (70 microM), to STS. In study B, we added Hoe (20 microM), Mex (70 microM), or a combination of Hoe (20 microM) and Mex (70 microM) to KHBB during the first 3 min of Langendorff reperfusion. RESULTS: In study A, the addition of Hoe (10 and 20 microM) to STS showed a significantly greater postischemic recovery of cardiac output compared to the control group [63.1+/-5.7% (10 microM), 62.7+/-4.7% (20 microM), and 55.5+/-4.6% (control), respectively]. The postischemic recovery of cardiac output was significantly greater in the group of the combined addition (Hoe and Mex) to STS than that in the control, 20 microM Hoe, 70 microM Mex groups [70.3+/-3.7 (Hoe and Mex), 55.5+/-4.6% (control), 62.7+/-4.7% (Hoe 20 microM), and 60.2+/-4.7% (Mex 70 microM), respectively]. The myocardial water content in the postischemic period was 565.1+/-29.1, 525.8+/-2.9, 509.4+/-19.6, and 532.2+/-20.1; it was 497.3+/-9.1 mL/100 g dry weight in the control; and 10 microM Hoe, 20 microM Hoe, and 70 microM Mex in the combined use groups. In study B, there was no significant difference in the postischemic recovery of cardiac output in all experimental groups. CONCLUSION: The combined use of the Na+-H+ exchange inhibitor and Na+ channel blocker during cardioplegia may achieve a superior cardioprotective effect on myocardial damage because of ischemia and reperfusion.  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