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   59010篇
  免费   5599篇
  国内免费   1987篇
耳鼻咽喉   189篇
儿科学   2474篇
妇产科学   342篇
基础医学   4593篇
口腔科学   447篇
临床医学   6959篇
内科学   18952篇
皮肤病学   332篇
神经病学   810篇
特种医学   2391篇
外国民族医学   7篇
外科学   4991篇
综合类   11067篇
现状与发展   7篇
预防医学   2614篇
眼科学   502篇
药学   5603篇
  48篇
中国医学   3182篇
肿瘤学   1086篇
  2024年   79篇
  2023年   1062篇
  2022年   1450篇
  2021年   2517篇
  2020年   2770篇
  2019年   2452篇
  2018年   2494篇
  2017年   2598篇
  2016年   2517篇
  2015年   2567篇
  2014年   4162篇
  2013年   4716篇
  2012年   3751篇
  2011年   3900篇
  2010年   3208篇
  2009年   2944篇
  2008年   2848篇
  2007年   2871篇
  2006年   2559篇
  2005年   2247篇
  2004年   1767篇
  2003年   1480篇
  2002年   1272篇
  2001年   1108篇
  2000年   874篇
  1999年   754篇
  1998年   603篇
  1997年   522篇
  1996年   525篇
  1995年   508篇
  1994年   473篇
  1993年   357篇
  1992年   340篇
  1991年   273篇
  1990年   273篇
  1989年   204篇
  1988年   194篇
  1987年   189篇
  1986年   170篇
  1985年   196篇
  1984年   167篇
  1983年   85篇
  1982年   118篇
  1981年   98篇
  1980年   79篇
  1979年   56篇
  1978年   48篇
  1977年   39篇
  1976年   40篇
  1975年   24篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
51.
52.
53.
54.
In 2017, the Canadian Association of Radiologists issued a clinical practice guideline (CPG) regarding the use of gadolinium-based contrast agents (GBCAs) in patients with acute kidney injury (AKI), chronic kidney disease (CKD), or on dialysis due to mounting evidence indicating that nephrogenic systemic fibrosis (NSF) occurs with extreme rarity or not at all when using Group II GBCAs or the Group III GBCA gadoxetic acid (compared to first generation Group I linear GBCAs). One of the goals of the work group was to re-evaluate the CPG after 24 months to determine the effect of more liberal use of GBCA on reported cases of NSF in patients with AKI, CKD Stage 4 or 5 (estimated glomerular filtration rate [eGFR] < 30 mL/min/1.73 m2), or those that are dialysis-dependent. A comprehensive review of the literature was conducted by a subcommittee of the initial CPG panel between the dates of January 1, 2017-December 31, 2018 to identify new unconfounded cases of NSF linked to Group II or Group III GBCAs and an updated CPG developed. To our knowledge, when using a Group II or Group III GBCA between 2017-2018, only a single unconfounded case report of a fibrosing dermopathy has been reported in a patient who received gadobenate dimeglumine with Stage 2 CKD. No other unconfounded cases of NSF have been reported with Group II or III agents in during this timeframe. The subcommittee concluded that the main recommendations from the 2017 CPG should remain unaltered, but agreed that screening for renal disease in the outpatient setting is no longer justifiable, cost-effective or recommended. Patients on hemodialysis (HD) should, however, be identified prior to GBCA administration to arrange timely HD to optimize gadolinium clearance, although there remains no evidence that HD reduces the risk of NSF. When administering Group II or III GBCAs to patients with AKI, on dialysis or with severe CKD, informed consent relating to NSF is also no longer explicitly recommended.  相似文献   
55.
56.

Background

A pulmonary hypertensive crisis (PHC) can be a life-threatening condition. We established a PHC model by exposing rats with monocrotaline (MCT)-induced pulmonary hypertension to acute hypoxia, and investigated the effects of vasopressin, phenylephrine, and norepinephrine on the PHC.

Methods

Four weeks after MCT 60 mg kg?1 administration i.v., right ventricular systolic pressure (RVSP), systolic BP (SBP), mean BP (MBP), cardiac index (CI), and pulmonary vascular resistance index (PVRI) were measured. PHC defined as an RVSP exceeding or equal to SBP was induced by changing the fraction of inspiratory oxygen to 0.1. Rats were subsequently treated by vasopressin, phenylephrine, or norepinephrine, followed by assessment of systemic haemodynamics, isometric tension of femoral and pulmonary arteries, cardiac function, blood gas composition, and survival.

Results

PHC was associated with increased RV dilatation and paradoxical septal motion. Vasopressin increased MBP [mean (standard error)] from 52.6 (3.8) to 125.0 (8.9) mm Hg and CI from 25.4 (2.3) to 40.6 (1.8) ml min?1 100 g?1 while decreasing PVRI. Vasopressin also improved RV dilatation, oxygenation, and survival in PHC. In contrast, phenylephrine increased MBP from 54.8 (2.3) to 96.8 (3.2) mm Hg without improving cardiac pump function. Norepinephrine did not alter MBP. Vasopressin contracted femoral but not pulmonary arteries, whereas phenylephrine contracted both arterial beds. Hence, improvements with vasopressin in PHC might be associated with decreased PVRI and selective systemic vasoconstriction.

Conclusions

In this rat model of a PHC, vasopressin, but not phenylephrine or norepinephrine, resulted in better haemodynamic and vascular recovery.  相似文献   
57.
全身型幼年特发性关节炎是儿童常见的风湿性疾病之一, 肺间质病变是指以肺间质和远端气隙重构为特征, 进而导致异常气体交换的疾病。近年来, 国内外对全身型幼年特发性关节炎合并肺间质病变的报道有增多趋势。该文总结了近年来报道中全身型幼年特发性关节炎儿童合并肺间质病变的情况, 并对儿童肺间质病变的临床表现, 影像学表现, 诊断和治疗进行综述,旨在对该类疾病有更深刻的认识, 有助于肺间质病变的早期诊治。  相似文献   
58.
《Vaccine》2022,40(19):2679-2695
Vaccinations are essential for preventing infectious diseases in children with chronic diseases as they have increased risk of infection from frequent use of biologics. Response to immunizations in this group is not well known.ObjectiveA systematic review was performed to evaluate three primary outcomes: efficacy; immunogenicity; and safety of vaccines in children with chronic conditions treated with biologics.MethodsThe protocol for our systematic review and meta-analysis was registered and published with PROSPERO. We searched electronic bibliographic databases for studies published from 2009 to 2019, focusing on vaccinations in children with chronic conditions treated with biologics.ResultsWe retrieved 532 records. Thirty-one full-text articles were selected, and 14 were included in the meta-analysis. No significant publication bias was found. Efficacy: limited data are available regarding the efficacy of vaccination, as most studies have focused on immunogenicity as surrogate outcome for efficacy. Immunogenicity: patients receiving anti-TNF-alpha therapy had a statistically significant risk of poor seroconversion (p = 0.028) and seroprotection by the serotype B influenza vaccine [inflammatory bowel disease (IBD) p = 0.013; juvenile idiopathic arthritis (JIA) p = 0.004]. We found adequate responses with H1N1 and H3N2 serotypes. Few studies existed for pneumococcal, hepatitis A virus, hepatitis B virus, varicella-zoster virus, Measles Mumps Rubella virus, and multiple vaccine administration. Safety: vaccine administration was not associated with serious side effects, but JIA patients on anti-TNF alpha therapy had a statistically significant risk of presenting with myalgia or arthralgia postinfluenza vaccine (p = 0.014).ConclusionsMore evidence concerning efficacy, immunogenicity, and safety of vaccinations is needed to guide physicians in the vaccine decision process for this pediatric population.  相似文献   
59.
代谢相关脂肪性肝病既往称为非酒精性脂肪肝,与肥胖、糖尿病、高脂血症等关系密切,还明显增加心血管死亡的风险。大黄素是大黄、何首乌中主要的活性成分,具有多种生物学功能。大黄素可通过降低肝细胞脂质沉积、抑制肝脏炎症反应、抗胰岛素抵抗、抑制肝纤维化、抗氧化应激反应等多种途径对代谢相关脂肪性肝病发挥治疗作用。总结了大黄素治疗代谢相关脂肪性肝病的作用机制,为代谢相关脂肪性肝病的治疗提供参考。  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