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   310423篇
  免费   25583篇
  国内免费   9727篇
耳鼻咽喉   1750篇
儿科学   10301篇
妇产科学   2259篇
基础医学   26864篇
口腔科学   4561篇
临床医学   35788篇
内科学   82743篇
皮肤病学   3455篇
神经病学   28528篇
特种医学   9462篇
外国民族医学   12篇
外科学   24551篇
综合类   45919篇
现状与发展   41篇
一般理论   14篇
预防医学   21726篇
眼科学   2802篇
药学   23495篇
  239篇
中国医学   15506篇
肿瘤学   5717篇
  2024年   758篇
  2023年   5799篇
  2022年   9776篇
  2021年   15110篇
  2020年   14684篇
  2019年   11725篇
  2018年   11402篇
  2017年   11466篇
  2016年   11878篇
  2015年   11595篇
  2014年   21254篇
  2013年   23508篇
  2012年   17857篇
  2011年   19345篇
  2010年   15415篇
  2009年   14781篇
  2008年   14579篇
  2007年   14561篇
  2006年   12896篇
  2005年   11068篇
  2004年   9340篇
  2003年   8205篇
  2002年   7008篇
  2001年   6195篇
  2000年   5084篇
  1999年   4472篇
  1998年   4048篇
  1997年   3733篇
  1996年   3350篇
  1995年   2987篇
  1994年   2775篇
  1993年   2303篇
  1992年   2186篇
  1991年   1914篇
  1990年   1545篇
  1989年   1386篇
  1988年   1251篇
  1987年   1118篇
  1986年   999篇
  1985年   1211篇
  1984年   1022篇
  1983年   608篇
  1982年   720篇
  1981年   636篇
  1980年   499篇
  1979年   398篇
  1978年   328篇
  1977年   283篇
  1976年   248篇
  1975年   117篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
142.
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   
143.
目的 通过阿霉素(Dox)复制大鼠慢性心力衰竭(CHF)模型,观察Liguzinediol对CHF大鼠心功能的影响。方法 通过血流动力学观察Liguzinediol对Dox(腹腔注射,2 mg/kg)诱导的CHF大鼠左心室内压最大上升/下降速率(±dp/dtmax)、左心室内压(LVSP)、动脉收缩压(ASP)、动脉舒张压(ADP)和心率(HR)的变化;观察Liguzinediol对血清一氧化氮(NO)、一氧化氮合成酶(NOS)、超氧化物歧化酶(SOD)、肿瘤坏死因子-α(TNF-α)和白细胞介素-6(IL-6)以及血浆中丙二醛(MDA)的影响。结果 Liguzinediol能增加LVSP、+dp/dtmax、ASP、ADP、AP、HR,降低-dp/dtmax(P<0.05~0.01);降低NO、iNOS以及MDA的浓度,同时增强了SOD的活性(P<0.05~0.01);抑制IL-6和TNF-α的生成(P<0.05~0.01)。结论 Liguzinediol可明显改善Dox诱导的CHF大鼠血流动力学指标,减少模型大鼠炎症因子的释放以及抑制氧自由基的生成。   相似文献   
144.
145.
146.
慢性肾脏病是一种以肾脏功能的损伤为主要表现,并可累及全身多脏器的慢性进展性疾病。中医辨证治疗本病在延缓病情、改善预后等方面具有显著的优势。通过中医理论研究及临床经验总结,笔者提出从“肾毒”论治慢性肾脏病,认为其不仅是本病的致病因素,更是重要的病理产物,是本病发生发展、迁延难愈的关键。在治疗上提出以“益肾元、解肾毒”为大法,并根据不同兼夹辨证施治,采用药对,长治缓图。以“肾毒”立论拟定的经验方苏茵解毒方,在临床治疗和实验研究上均显示出明显的效果,并已制备成院内制剂临床使用,在疗效及经济效益方面均具有显著的优势。  相似文献   
147.
BackgroundParkinson’s disease (PD) is a chronic and progressive neurodegenerative disease with no cure, presenting a challenging diagnosis and management. However, despite a significant number of criteria and guidelines have been proposed to improve the diagnosis of PD and to determine the PD stage, the gold standard for diagnosis and symptoms monitoring of PD is still mainly based on clinical evaluation, which includes several subjective factors. The use of machine learning (ML) algorithms in spatial-temporal gait parameters is an interesting advance with easy interpretation and objective factors that may assist in PD diagnostic and follow up.Research questionThis article studies ML algorithms for: i) distinguish people with PD vs. matched-healthy individuals; and ii) to discriminate PD stages, based on selected spatial-temporal parameters, including variability and asymmetry.MethodsGait data acquired from 63 people with PD with different levels of PD motor symptoms severity, and 63 matched-control group individuals, during self-selected walking speed, was study in the experiments.ResultsIn the PD diagnosis, a classification accuracy of 84.6 %, with a precision of 0.923 and a recall of 0.800, was achieved by the Naïve Bayes algorithm. We found four significant gait features in PD diagnosis: step length, velocity and width, and step width variability. As to the PD stage identification, the Random Forest outperformed the other studied ML algorithms, by reaching an Area Under the ROC curve of 0.786. We found two relevant gait features in identifying the PD stage: stride width variability and step double support time variability.SignificanceThe results showed that the studied ML algorithms have potential both to PD diagnosis and stage identification by analysing gait parameters.  相似文献   
148.
Rifamycins (rifampin, rifabutin, and rifapentine) play an essential role in the treatment of mycobacterial and some nonmycobacterial infections. They also induce the activity of various drug transporting and metabolizing enzymes, which can impact the concentrations and efficacy of substrates. Many anticoagulant and antiplatelet (AC/AP) agents are substrates of these enzymes and have narrow therapeutic indices, leading to risks of thrombosis or bleeding when coadministered with rifamycins. The objective of this systematic review was to evaluate the effects on AC/AP pharmacokinetics, laboratory markers, and clinical safety and efficacy of combined use with rifamycins. A systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidance was performed. The PubMed, Embase, and Web of Science databases were queried for English-language reports on combination use of rifamycins and AC/AP agents from database inception through August 2021. The 29 studies identified examined warfarin (n = 17), direct oral anticoagulants (DOACs) (n = 8), and antiplatelet agents (n = 4) combined with rifampin (n = 28) or rifabutin (n = 1). Eleven studies were case reports or small case series; 14 reported on pharmacokinetic or laboratory markers in healthy volunteers. Rifampin-warfarin combinations led to reductions in warfarin area under the curve (AUC) of 15%–74%, with variability by warfarin isomer and study. Warfarin dose increases of up to 3–5 times prerifampin doses were required to maintain coagulation parameters in the therapeutic range. DOAC AUCs were decreased by 20%–67%, with variability by individual agent and with rifampin versus rifabutin. The active metabolite of clopidogrel increased substantially with rifampin coadministration, whereas prasugrel was largely unaffected and ticagrelor saw decreases. Our review suggests most combinations of AC/AP agents and rifampin are problematic. Further studies are required to determine whether rifabutin or rifapentine could be safe alternatives for coadministration with AC/AP drugs.  相似文献   
149.
Chronic pain in the UK affects up to 43% of the population. The consequences include physical and psychological distress, loss of function, employment, family and social strain and increased utilization of healthcare services. Modern pain management services operate across primary, secondary and tertiary care and incorporate general practitioners, psychologists, physiotherapists, pharmacists, specialist nurses, pain physicians and surgeons. This allows for a coordinated approach to chronic pain, engaging the patient in a structured pathway from conservative measures, through to surgery if necessary. Surgical interventions have been utilized effectively throughout the 20th century for the treatment of a variety of conditions, some of which are now effectively managed with improved pharmacological approaches or novel neuromodulation techniques. Ablative procedures that aim to permanently interrupt the pain pathway still represent the final solution for some conditions, particularly those with cancer associated pain; however, the search for less invasive, less risky measures continues. This is stimulated by an increased understanding of the neurobiology of pain transmission and the physiological changes which occur in persistent pain.  相似文献   
150.
IntroductionSunlight exposure is the main source of vitamin D. Our aim was to describe both sun exposure and sun protection behaviour in a series of patients with inflammatory bowel disease (IBD), and to study their potential association with vitamin D concentration.Patients and methodsA cross sectional, observational study. The clinical-demographic variables were obtained via clinical interviews and medical history review. The sunlight exposure assessment was carried out using the Sun Exposure Questionnaire and the concentration of 25-hydroxy vitamin D (25OHD) was measured by an electro-chemiluminescence immunoassay. Questionnaires were conducted on quality of life, physical activity, weekly vitamin D intake and sun protection behaviour.Results149 patients were included. In 69% of patients, deficient or insufficient 25OHD values were recorded. 67% showed low sun exposure. A modest significant correlation was observed between the total score of the solar exposure questionnaire and the 25OHD concentration in the complete series (r = 0.226, P = .006) and in the summer (r = 0.274, P = .01). The sun protection behaviour questionnaire score did not influence the 25OHD concentration. In the multivariate analysis, only the presence of clinical activity was associated with low sun exposure (OR = 3.23).DiscussionSun exposure according to the questionnaire used was low, was associated with the presence of clinical activity and was weakly correlated with serum 25OHD concentration. More studies are needed to explore the use of individual questionnaires for sun exposure and its relationship with vitamin D in patients with IBD.  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