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   95873篇
  免费   6895篇
  国内免费   2723篇
耳鼻咽喉   436篇
儿科学   2229篇
妇产科学   878篇
基础医学   7294篇
口腔科学   1107篇
临床医学   10462篇
内科学   18808篇
皮肤病学   613篇
神经病学   3566篇
特种医学   3145篇
外国民族医学   14篇
外科学   8973篇
综合类   18884篇
现状与发展   3篇
一般理论   4篇
预防医学   6982篇
眼科学   964篇
药学   8578篇
  156篇
中国医学   9766篇
肿瘤学   2629篇
  2024年   221篇
  2023年   1605篇
  2022年   2418篇
  2021年   4176篇
  2020年   4021篇
  2019年   3874篇
  2018年   3547篇
  2017年   3479篇
  2016年   3426篇
  2015年   3167篇
  2014年   6540篇
  2013年   6384篇
  2012年   5745篇
  2011年   6546篇
  2010年   5770篇
  2009年   4551篇
  2008年   4226篇
  2007年   4392篇
  2006年   4044篇
  2005年   3468篇
  2004年   2814篇
  2003年   2537篇
  2002年   1872篇
  2001年   1680篇
  2000年   1402篇
  1999年   1249篇
  1998年   1015篇
  1997年   992篇
  1996年   849篇
  1995年   843篇
  1994年   760篇
  1993年   595篇
  1992年   590篇
  1991年   500篇
  1990年   442篇
  1989年   395篇
  1988年   390篇
  1987年   334篇
  1986年   315篇
  1985年   578篇
  1984年   533篇
  1983年   390篇
  1982年   434篇
  1981年   421篇
  1980年   401篇
  1979年   344篇
  1978年   298篇
  1977年   268篇
  1976年   207篇
  1975年   124篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
Purpose: Small pulmonary lesions that include ground-glass attenuation have been increasingly discovered because of progressive imaging diagnostic technologies. Despite the detection of such small lesions, sometimes it is quite difficult to localize them because of their size or considerable depth from the visceral pleura. In the present study, we examined the usefulness of computed tomography-guided lipiodol marking for thoracoscopic resection of impalpable pulmonary nodules.Methods: Fifty-six patients with an undiagnosed peripheral lesion(s) of the lung who had undergone preoperative computed tomography-guided lipiodol marking followed by video-assisted thoracoscopic surgery were studied.Results: All of the nodules were successfully marked by computed tomography-guided lipiodol marking, and all except for one case were localized by means of intraoperative fluoroscopy as clear spots. With regard to complications, pneumothorax occurred in 21 patients (37.5%), and only one patient required transient drainage. Although hemorrhaging in the lung parenchyma and hemosputum occurred in nine patients (16.1%) and one patient (1.8%), respectively, no patients were in serious condition. No intra- or postoperative mortality or morbidity was observed.Conclusion: Preoperative computed tomography-guided lipiodol marking of small or impalpable pulmonary nodules is a safe and useful procedure for thoracoscopic resection of the lung.  相似文献   
52.
53.
结合验案分析,基于"祛邪为第一要义"探讨新型冠状病毒肺炎从清热化湿论治的思路与方法。认为新型冠状病毒肺炎主要是属于"湿热"性质的疫病,治疗应强调清热化湿,以"祛邪为第一要义",辅以扶正。在中医祛邪与扶正理论指导下,通过宣肺平喘、通腑泻热、芳香化湿等治法,祛邪为主,肺肠合治,可以使发热减轻或消退,使大便通畅,从而截断病情进展,避免或减少危重症的发生及死亡的风险;通过清热化湿、疏肝健脾、凉血化瘀等治法,祛邪兼以扶正,肺与肝、脾合调,可以改善肝功能损伤,减少病情加重的风险;通过补气健脾等扶正治法,可以改善患者的精神和体力,促使病毒更快转阴,缩短病程,促进患者早日康复。  相似文献   
54.
Pulmonary hypertension of the newborn (PHN) constitutes a critical condition with severe cardiovascular and neurological consequences. One of its main causes is hypoxia during gestation, and thus, it is a public health concern in populations living above 2500 m. Although some mechanisms are recognized, the pathophysiological facts that lead to PHN are not fully understood, which explains the lack of an effective treatment. Oxidative stress is one of the proposed mechanisms inducing pulmonary vascular dysfunction and PHN. Therefore, we assessed whether melatonin, a potent antioxidant, improves pulmonary vascular function. Twelve newborn sheep were gestated, born, and raised at 3600 meters. At 3 days old, lambs were catheterized and daily cardiovascular measurements were recorded. Lambs were divided into two groups, one received daily vehicle as control and another received daily melatonin (1 mg/kg/d), for 8 days. At 11 days old, lung tissue and small pulmonary arteries (SPA) were collected. Melatonin decreased pulmonary pressure and resistance for the first 3 days of treatment. Further, melatonin significantly improved the vasodilator function of SPA, enhancing the endothelial‐ and muscular‐dependent pathways. This was associated with an enhanced nitric oxide‐dependent and nitric oxide independent vasodilator components and with increased nitric oxide bioavailability in lung tissue. Further, melatonin reduced the pulmonary oxidative stress markers and increased enzymatic and nonenzymatic antioxidant capacity. Finally, these effects were associated with an increase of lumen diameter and a mild decrease in the wall of the pulmonary arteries. These outcomes support the use of melatonin as an adjuvant in the treatment for PHN.  相似文献   
55.
目的:分析竹叶石膏汤合清气化痰丸加减治疗急性加重期慢性阻塞性肺疾病(Acute Exacerbations of Chronic Obstructive Pulmonary Disease,AECOPD)疗效。方法:以2017年1月-2019年1月收治的AECOPD患者80例,随机分为两组,各40例。对照组采用常规西药治疗,观察组在对照组基础上采用竹叶石膏汤合清气化痰丸加减治疗。比较两组治疗前后肺功能指标[第1秒用力呼气容积占预计值百分比(Forced Expiratory Volume,FEV1%)、第一秒用力呼气肺容积(Forced Expiratory Volume,FEV1)]、改良版英国医学研究委员会呼吸问卷(mMRC)、慢阻肺患者自我评估测试问卷(CAT)等评分变化以及疗效。结果:在FEV1%、FEV1等肺功能指标上,两组治疗前对比无统计学差异(P>0.05);而观察组治疗后均高于对照组,二者差异存在统计学意义(P<0.05)。在mMRC、CAT等评分上,两组治疗前差异对比无统计学意义(P>0.05);而观察组治疗后均低于对照组,二者差异存在统计学意义(P<0.05)。在治疗有效率上,对照组总体为82.5%(33/40),观察组总体为95.0%(38/40),二者差异对比存在统计学意义(P<0.05)。结论:竹叶石膏汤合清气化痰丸加减治疗AECOPD的疗效确切,即可有效改善患者肺功能和临床症状,且利于其预后康复,因此值得应用推广。  相似文献   
56.
Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital condition. It responds well to early diagnosis and treatment, but otherwise the prognosis is poor. We present our case series of 12 patients (mean age, 2 ± 2.58 yr; age range, 2 mo–8 yr), emphasizing the diagnostic process and discussing our surgical results. The diagnosis of ALCAPA should be suspected in infants who have dilated cardiomyopathy with electrocardiographic changes that suggest ischemia, and in older children who have isolated mitral regurgitation. When clinical suspicion is high, the results of 2-dimensional echocardiography combined with color-flow Doppler studies in expert hands can establish the diagnosis, thus avoiding angiography in critically ill infants. The treatment of choice in our patients was transfer and reimplantation of the left coronary artery onto the ascending aorta. There were 2 deaths: both were infants in extremis who underwent emergency surgery. An older child with severe ventricular dysfunction was given mechanical ventricular assistance and then heart transplantation. As of this report, all 10 survivors remained well and asymptomatic.  相似文献   
57.
58.
ObjectiveThe objective of this study was to investigate the association between morphological variation and postsurgical pulmonary vein (PV) stenosis (PPVS) in patients with cardiac total anomalous pulmonary venous connection (TAPVC).MethodsThis single-center, retrospective study included 168 pediatric patients who underwent surgical repair of cardiac TAPVC from 2013 to 2019 (connection to the coronary sinus [CS], n = 136; connection directly to the right atrium [RA], n = 32). Three-dimensional computed tomography modeling and geometric analysis were performed to investigate the morphological features; their relevance to the PPVS was examined.ResultsThe connection type had no association with PPVS (CS type: 18% vs right atrial type: 19%; P = .89) but there was a higher incidence of PPVS in patients with a single PV orifice than > 1 orifice (P < .001). Confluence-to-total PV area ratio (hazard ratio, 4.78, 95% CI, 1.86-12.32; P = .001) and length of drainage route (hazard ratio, 1.22; 95% CI, 1.14-1.31; P < .001) had a 4- and 1-fold increase in the risk for PPVS in the CS type after adjustment for age and preoperative pulmonary venous obstruction. In the right atrial type, those with anomalous PV return to the RA roof were more likely to develop PPVS than to the posterior wall of the RA (P < .001).ConclusionsThe number of inter-junction PV orifice correlated with PPVS development in cardiac TAPVC. The confluence-to-total PV ratio, length of drainage route, and anomalous PV return to the RA roof are important predictors for PPVS. Morphological subcategorization in this clinical setting can potentially assist in surgical decision-making.  相似文献   
59.
60.
1. To investigate Genkwa Flos hepatotoxicity, a cell metabolomics strategy combined with serum pharmacology was performed on human HL-7702 liver cells in this study.

2. Firstly, cell viability and biochemical indicators were determined and the cell morphology was observed to confirm the cell injury and develop a cell hepatotoxicity model. Then, with the help of cell metabolomics based on UPLC-MS, the Genkwa Flos group samples were completely separated from the blank group samples in the score plots and seven upregulated as well as two down-regulated putative biomarkers in the loading plot were identified and confirmed. Besides, two signal molecules and four enzymes involved in biosynthesis pathway of lysophosphatidylcholine and the sphingosine kinase/sphingosine-1-phosphate pathway were determined to investigate the relationship between Genkwa Flos hepatotoxicity and these two classic pathways. Finally, the metabolic pathways related to specific biomarkers and two classic metabolic pathways were analyzed to explain the possible mechanism of Genkwa Flos hepatotoxicity.

3. Based on the results, lipid peroxidation and oxidative stress, phospholipase A2/lysophosphatidylcholine pathway, the disturbance of sphingosine-1-phosphate metabolic profile centered on sphingosine kinase/sphingosine-1-phosphate pathway and fatty acid metabolism might be critical participators in the progression of liver injury induced by Genkwa Flos.  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