全文获取类型
收费全文 | 60856篇 |
免费 | 3615篇 |
国内免费 | 274篇 |
专业分类
耳鼻咽喉 | 825篇 |
儿科学 | 1467篇 |
妇产科学 | 934篇 |
基础医学 | 7195篇 |
口腔科学 | 1283篇 |
临床医学 | 6304篇 |
内科学 | 12773篇 |
皮肤病学 | 1052篇 |
神经病学 | 6123篇 |
特种医学 | 1886篇 |
外科学 | 10160篇 |
综合类 | 641篇 |
一般理论 | 70篇 |
预防医学 | 4460篇 |
眼科学 | 1275篇 |
药学 | 3667篇 |
3篇 | |
中国医学 | 59篇 |
肿瘤学 | 4568篇 |
出版年
2023年 | 295篇 |
2022年 | 492篇 |
2021年 | 1168篇 |
2020年 | 686篇 |
2019年 | 1188篇 |
2018年 | 1419篇 |
2017年 | 1087篇 |
2016年 | 1227篇 |
2015年 | 1373篇 |
2014年 | 1973篇 |
2013年 | 2759篇 |
2012年 | 4353篇 |
2011年 | 4782篇 |
2010年 | 2585篇 |
2009年 | 2411篇 |
2008年 | 4204篇 |
2007年 | 4374篇 |
2006年 | 4307篇 |
2005年 | 4318篇 |
2004年 | 4071篇 |
2003年 | 3873篇 |
2002年 | 3609篇 |
2001年 | 433篇 |
2000年 | 380篇 |
1999年 | 535篇 |
1998年 | 724篇 |
1997年 | 593篇 |
1996年 | 532篇 |
1995年 | 517篇 |
1994年 | 424篇 |
1993年 | 361篇 |
1992年 | 291篇 |
1991年 | 229篇 |
1990年 | 218篇 |
1989年 | 165篇 |
1988年 | 216篇 |
1987年 | 175篇 |
1986年 | 181篇 |
1985年 | 189篇 |
1984年 | 216篇 |
1983年 | 236篇 |
1982年 | 323篇 |
1981年 | 293篇 |
1980年 | 227篇 |
1979年 | 97篇 |
1978年 | 129篇 |
1977年 | 114篇 |
1976年 | 69篇 |
1974年 | 54篇 |
1973年 | 52篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
Conall T. Morgan Brigitte Mueller Varsha Thakur Vitor Guerra Callaghan Jull Luc Mertens Mark Friedberg Fraser Golding Mike Seed Steven E.S. Miner Edgar T. Jaeggi Cedric Manlhiot Lynne E. Nield 《The Canadian journal of cardiology》2019,35(4):453-461
Background
The purpose of the study was to evaluate the association between fetal echocardiographic measurements and the need for intervention (primary coarctation repair, staged coarctation repair, or catheter intervention) in prenatally diagnosed coarctation of the aorta.Methods
A single-centre retrospective cohort study (2005-2015) of 107 fetuses diagnosed with suspected coarctation of the aorta in the setting of an apex-forming left ventricle and antegrade flow across the mitral and aortic valves.Results
Median gestational age at diagnosis was 32 weeks (interquartile range, 23-35 weeks). Fifty-six (52%) did not require any neonatal intervention, 51 patients (48%) underwent a biventricular repair. In univariable analysis, an increase in ascending aorta (AAo) peak Doppler flow velocity (odds ratio [OR], 1.40 [95% confidence interval [CI], 1.05-1.91] per 20 cm/s; P = 0.03) was associated with intervention. No intervention was associated with larger isthmus size (OR, 0.23; P < 0.001), transverse arch diameter (OR, 0.23; P < 0.001), and aortic (OR, 0.72; P = 0.02), mitral (OR, 0.58; P = 0.001), and AAo (OR, 0.53; P < 0.001) z-scores. In multivariable analysis, higher peak AAo Doppler (OR, 2.51 [95% CI, 1.54-4.58] per 20 cm/s; P = 0.001) and younger gestational age at diagnosis (OR, 0.81 [95% CI, 0.70-0.93] per week; P = 0.005) were associated with intervention, whereas a higher AAo z-score (OR, 0.65 [95% CI, 0.43-0.94] per z; P = 0.029) and transverse arch dimension (OR, 0.44 [95% CI, 0.18-0.97]; P = 0.05) decreased the risk of intervention.Conclusions
In prenatally suspected coarctation, the variables associated with intervention comprised smaller AAo and transverse arch size, earlier gestational age at diagnosis, and the additional finding of a higher peak AAo Doppler. 相似文献3.
4.
Although hepatitis E virus (HEV) is the primary cause of enterically transmitted acute hepatitis and jaundice in developing countries, locally acquired HEV infections are increasing in nonendemic countries. As such, HEV is emerging as an underdiagnosed cause of infection. This report describes three clinically variable cases of HEV infection with unusual clinical presentations. These cases highlight the fact that HEV should be considered in the differential diagnosis of patients with unexplained hepatitis (acute or chronic) with or without extrahepatic manifestations. HEV should also be considered in patients with persistently elevated liver enzymes who have not travelled to known HEV-endemic regions. Lack of knowledge among physicians and an absence of standardized diagnostic tests may result in increased morbidity and mortality from HEV infection. 相似文献
5.
Jennifer Wang Jonathan G. Stine Scott L. Cornella Curtis K. Argo Steven M. Cohn 《临床与转化肝病杂志(英文版)》2015,3(4):254-259
Background and Aims: Gastric antral vascular ectasia (GAVE) is commonly found in patients with cirrhosis, but it is also associated with other diseases in the absence of cirrhosis. Whether GAVE confers a different severity of gastrointestinal (GI) bleeding between patients with and without cirrhosis remains unknown. We aim to examine whether there is a difference in clinically significant GI bleeding due to GAVE in patients with or without cirrhosis. Methods: This is a retrospective case-control study of patients who were diagnosed with GAVE between January 2000 and June 2014. Patients were categorized into cirrhosis and noncirrhosis groups, and those with an additional GI bleeding source were excluded. Univariate comparisons and multivariable models were constructed using logistic regression. Results: In total, 110 patients diagnosed with GAVE on esophagogastroduodenoscopy (EGD) were included in our analysis; 84 patients had cirrhosis (76.4%) and 26 (23.6%) did not. Active GI bleeding was more prevalent in patients without cirrhosis (63.4% vs. 32.1%, p=0.003) despite similar indications for EGD, and endoscopic treatment with argon plasma coagulation (APC) was required more often in this group, approaching statistical significance (27% vs. 10.7%, p=0.056). There was no difference in bleeding severity, as evidenced by similar re-bleeding rates, surgery, or death attributed to uncontrolled bleeding. The strongest independent risk factor for GI bleeding was the absence of cirrhosis (odds ratio (OR): 5.151 (95% confidence interval (CI): 1.08-24.48, p=0.039). Conclusions: Patients with GAVE in the absence of cirrhosis are at higher risk for active GI bleeding and require more frequent endoscopic treatment than similar patients with cirrhosis. It may be worthwhile to treat GAVE in this population even in the absence of active bleeding. 相似文献
6.
Nishard Abdeen Albert Cross Gregory Cron Steven White Thomas Rand David Miller Giles Santyr 《Magnetic resonance in medicine》2006,56(2):255-264
We used the dual capability of hyperpolarized 129Xe for spectroscopy and imaging to develop new measures of xenon diffusing capacity in the rat lung that (analogously to the diffusing capacity of carbon monoxide or DLCO) are calculated as a product of total lung volume and gas transfer rate constants divided by the pressure gradient. Under conditions of known constant pressure breath-hold, the volume is measured by hyperpolarized 129Xe MRI, and the transfer rate is measured by dynamic spectroscopy. The new quantities (xenon diffusing capacity in lung parenchyma (DLXeLP)), xenon diffusing capacity in RBCs (DLXeRBC), and total lung xenon diffusing capacity (DLXe)) were measured in six normal rats and six rats with lung inflammation induced by instillation of fungal spores of Stachybotrys chartarum. DLXeLP, DLXeRBC, and DLXe were 56 +/- 10 ml/min/mmHg, 64 +/- 35 ml/min/mmHg, and 29 +/- 9 ml/min/mmHg, respectively, for normal rats, and 27 +/- 9 ml/min/mmHg, 42 +/- 27 ml/min/mmHg, and 16 +/- 7 ml/min/mmHg, respectively, for diseased rats. Lung volumes and gas transfer times for LP (TtrLP) were 16 +/- 2 ml and 22 +/- 3 ms, respectively, for normal rats and 12 +/- 2 ml and 35 +/- 8 ms, respectively, for diseased rats. Xenon diffusing capacities may be useful for measuring changes in gas exchange associated with inflammation and other lung diseases. 相似文献
7.
Steven V Koenen Anjoke J M Huisjes Jules Dings Yolanda van der Graaf Gerard H A Visser Hein W Bruinse 《The journal of maternal-fetal & neonatal medicine》2006,19(2):93-99
OBJECTIVE: To determine if there is a diurnal pattern in the clinical symptoms of HELLP (Hemolysis, Elevated Liver enzymes, Low Platelets) syndrome. STUDY DESIGN: A retrospective study was performed in 134 pregnancies complicated by HELLP syndrome. The medical records were reviewed to describe each HELLP episode. Time of day was divided into three periods, day, evening, and night. The following parameters were categorized according to the time of day: onset of symptoms, consultation by the doctor, initial blood sampling, diagnosis and decrease of symptoms. Biochemical parameters at clinical presentation and consecutive changes within 24 h were recorded. RESULTS: In 65 pregnancies 77 HELLP episodes were well documented. Times of onset of symptoms and consultation by the doctor were significantly higher during the evening and night (p < 0.001), whereas times of diagnosis and decrease of symptoms occurred significantly more during the day (p < 0.001). In only 49.3% of the cases were diagnostic laboratory criteria met at clinical presentation. This was mainly due to platelet values in excess of 100 x 10(9)/l. Several hours later (median 8 h, range 2-23) the decrease in platelets occurred. CONCLUSIONS: A diurnal pattern exists in the clinical symptoms of HELLP syndrome that is characterized by an exacerbation during the night and recovery during the day. There is a considerable delay between the onset of symptoms and the fulfillment of diagnostic laboratory criteria. 相似文献
8.
9.
Patricia A Wilkosz Sachiko Miyahara Oscar L Lopez Steven T Dekosky Robert A Sweet 《The American journal of geriatric psychiatry》2006,14(4):352-360
BACKGROUND: Psychotic symptoms in Alzheimer disease (AD+P) identify a heritable phenotype associated with more rapid cognitive decline. The authors have proposed that AD+P is itself a composite of a misidentification and a paranoid subtype with increased cognitive impairment restricted to the misidentification type. Most prior studies of the clinical correlates of AD+P have been limited, however, by the inclusion of prevalent cases. METHODS: Subjects with possible or probable AD or mild cognitive impairment (MCI) without psychosis at study entry were assessed at the time of initial presentation and then annually. Psychotic symptoms were assessed using the CERAD Behavioral Rating Scale. Survival analyses used Cox proportional hazard models with time-dependent covariates to examine the predictors of psychosis onset. RESULTS: A total of 288 subjects completed at least one follow-up examination. Mean duration of follow-up was 22.1 months. The incidence of psychosis was 0.19 per person-year. Cognitive impairment was associated with onset of psychosis, largely as a result of its association with onset of the misidentification, but not the paranoid, subtype. Including psychotropic medication use in the model revealed an association of antidepressant use with the onset of psychosis. This latter association appeared to arise from an underlying association between depression and the risk of psychosis onset rather than from antidepressant treatment. CONCLUSION: These findings are consistent with the hypothesis that the misidentification and the paranoid subtypes each define a more biologically homogeneous group than AD+P as a whole. Further exploration of the relationship between depressive symptoms and psychosis in patients with AD is warranted. 相似文献
10.