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   1120篇
  免费   46篇
耳鼻咽喉   7篇
儿科学   25篇
妇产科学   15篇
基础医学   127篇
口腔科学   7篇
临床医学   77篇
内科学   239篇
皮肤病学   101篇
神经病学   116篇
特种医学   43篇
外科学   164篇
综合类   2篇
一般理论   1篇
预防医学   76篇
眼科学   1篇
药学   114篇
中国医学   2篇
肿瘤学   49篇
  2022年   12篇
  2021年   23篇
  2020年   18篇
  2019年   16篇
  2018年   20篇
  2017年   14篇
  2016年   17篇
  2015年   16篇
  2014年   27篇
  2013年   36篇
  2012年   63篇
  2011年   76篇
  2010年   44篇
  2009年   25篇
  2008年   67篇
  2007年   58篇
  2006年   41篇
  2005年   50篇
  2004年   58篇
  2003年   40篇
  2002年   44篇
  2001年   32篇
  2000年   45篇
  1999年   45篇
  1998年   10篇
  1997年   12篇
  1996年   15篇
  1995年   7篇
  1994年   7篇
  1993年   7篇
  1992年   21篇
  1991年   12篇
  1990年   21篇
  1989年   17篇
  1988年   15篇
  1987年   16篇
  1986年   18篇
  1985年   15篇
  1984年   8篇
  1983年   9篇
  1982年   3篇
  1981年   4篇
  1979年   9篇
  1978年   9篇
  1977年   8篇
  1976年   5篇
  1974年   5篇
  1973年   5篇
  1968年   3篇
  1966年   3篇
排序方式: 共有1166条查询结果,搜索用时 15 毫秒
21.
22.
This study aimed at differentiating between memory‐ and task‐related processes and their correlates on the electrodermal and electrocortical level during information concealment. Variations of the Guilty Knowledge Test were implemented in two experiments while we measured skin conductance responses (SCRs) and event‐related brain potentials. P300 amplitudes were specifically enhanced for items requiring a deviant behavioral response but they were not sensitive to concealed knowledge. In contrast, N200 amplitudes differed between memorized and irrelevant items in both experiments. SCR measures reflected a combined influence of task relevance and probe recognition, and they provided incremental validity above N200 amplitudes. These results suggest that the P300 mainly reflects task relevance in the given experimental setting whereas the N200 amplitude is sensitive to previously encoded information and potentially linked to response monitoring processes.  相似文献   
23.
We analyzed mutations in the 5' non-coding region of the BCL-6 gene in 46 cases of primary cutaneous B-cell lymphomas (PCBCL), using a polymerase chain reaction single strand conformation polymorphism (PCR-SSCP) method. The results indicate that PCBCL display a low frequency of mutations and support a marginal zone B-cell origin for most of these neoplasms.  相似文献   
24.
25.
In untreated patients with uncomplicated essential hypertension, exercise induces an abnormal increase in blood pressure; the influences of this increase on exercise were evaluated by a cardiopulmonary exercise test (CPX) performed in control conditions (step 1) and during acute blood pressure reduction (step 2). Patients were classified as (1) normotensive (resting diastolic blood pressure [BPd] less than 90 mm Hg; n = 14), (2) mildly hypertensive (BPd of 90 to 104 mm Hg; n = 9), and (3) moderately to severely hypertensive (BPd greater than or equal to 105 mm Hg; n = 16). For the three groups, peak mean blood pressure during exercise was 125 +/- 5 mm Hg (mean +/- SEM), 144 +/- 3 mm Hg (p less than 0.01 vs normotensive), and 161 +/- 4 mm Hg (p less than 0.01 vs normotensive and p less than 0.01 vs mild hypertension), respectively. Oxygen consumption (VO2) at peak exercise and at ventilatory anaerobic threshold was 26.1 +/- 1.1 and 17.2 +/- 0.5 ml/min/kg, 25.4 +/- 1.1 and 16.9 +/- 0.8 ml/min/kg, and 26.4 +/- 1.3 and 17.5 +/- 1.2 ml/min/kg in normotensive subjects, those with mild hypertension, and those with moderate to severe hypertension, respectively. Fourteen normotensive subjects, six with mild hypertension, and nine with moderate to severe hypertension participated to step 2 (nifedipine vs placebo, double-blind crossover). Nifedipine reduced blood pressure at rest and at peak exercise in those with hypertension. Peak exercise VO2 was unaffected by nifedipine in both normotensive subjects and those with hypertension. With nifedipine, ventilatory anaerobic threshold occurred earlier and at a lower VO2 in mild and in moderate to severe hypertension (delta VO2 = -1.9 and -2.4 ml/min/kg, respectively). These findings might be due to nifedipine-induced redistribution of blood flow during exercise and might be the reason for the complaint of weakness after blood pressure reduction in hypertensive subjects.  相似文献   
26.
ObjectivesThis study aimed to investigate cardiac computed tomography (CT) and transesophageal echocardiography (TEE) peridevice leak (PDL) assessments, and the clinical relevance of PDL.BackgroundPDL assessment is integral during follow-up after left atrial appendage (LAA) occlusion. Comparative studies of TEE and cardiac CT are sparse, and the clinical relevance of PDL is uncertain.MethodsThis was a single-center observational study of consecutive patients undergoing LAA occlusion with Amplatzer devices (Amplatzer Cardiac Plug/Amulet) between 2010 and 2018 (N = 415). Patients with both 8-week CT and TEE were included for analysis (n = 346). Images were analyzed by blinded investigators (K.K. and A.S.). PDL on cardiac CT was classified from grade 1 to 3, based on PDL at the device disc, device lobe, and LAA contrast patency. Primary clinical outcome was a composite of ischemic stroke, transient ischemic attack, systemic embolism, or all-cause death.ResultsPDL was present in 110 patients (32%) by TEE, with 29 (8%) >3 mm. By cardiac CT, 210 patients (61%) had PDL at the disc, with contrast patency in 204 patients (59%). A grade 3 PDL (gap at disc, lobe, and LAA contrast patency) was present in 63 patients (18%). Bland-Altman analysis showed poor agreement between CT and TEE for leak sizing. CT and TEE detected PDL was not significantly associated with worse outcome, hazard ratio: 1.82 (95 % confidence interval: 0.95 to 3.50); p = 0.07 and hazard ratio: 1.43 (95% confidence interval: 0.74 to 2.76); p = 0.28, respectively.ConclusionsPDL occurrence is substantially higher with CT compared with TEE, with a large discrepancy between modalities in leak quantification. A novel CT-based classification is proposed, yet PDL was not associated with worse clinical outcome.  相似文献   
27.
28.
BackgroundHigh-risk coronary atherosclerosis features evaluated coronary CT angiography (CCTA) were suggested to have a prognostic role. The present study aimed to evaluate the association of circulating biomarkers with high-risk plaque features assessed by CCTA.MethodsA consecutive cohort of subjects who underwent CCTA because of suspected CAD was screened for inclusion in the CAPIRE study. Based on risk factors (RF) burden patients were defined as having a low clinical risk (0–1 RF with the exclusion of patients with diabetes mellitus as single RF) or an high clinical risk (≥3 RFs). In all patients, measurement of inflammatory biomarkers and CCTA analysis focused on high-risk plaque features were performed. Univariate and multivariate logistic regression analysis were used to evaluate the relationship between clinical and biological variables with CCTA advanced plaque features.Results528 patients were enrolled in CAPIRE study. Older age and male sex appeared to be predictors of qualitative high-risk plaque features and associated with the presence of elevated total, non-calcified and low-attenuation plaque volume. Among circulating biomarkers only hs-CRP was found to be associated with qualitative high-risk plaque features (OR 2.02, p = 0.004 and 2.02, p = 0.012 for LAP and RI > 1.1, respectively) with borderline association with LAP-Vol (OR 1.52, p = 0.076); HbA1c and PTX-3 resulted to be significantly associated with quantitative high-risk plaque features (OR 1.71, p = 0.003 and 1.04, p = 0.002 for LAP-Vol, respectively).ConclusionsOur results support the association between inflammatory biomarkers (hs-CRP, PTX- 3), HbA1c and high-risk atherosclerotic features detected by CCTA. Male sex and older age are significant predictors of high-risk atherosclerosis.  相似文献   
29.
Violacein (Viol) is a pigment produced by several Gram-negative bacteria with many bioactivities, such as anticancer, virucide, and antiparasitic. However, violacein is insoluble under physiological conditions preventing its potential therapeutic uses. Surface-active ionic liquids (SAILs) based on the cation 1-alkylimidazolium ([CnHim]) with n = 10 to 16 alkyl carbon side chain lengths and acetate, bromide, methanesulfonate (S) or trifluoroacetate (F) as counterions were synthesized and screened to dissolve Viol in micellar aqueous media and for toxicological studies on the human lung carcinoma A549 cell line. Screening allowed the selection of 1.5 × 10−3% (w/v) [C16Him]-S because it combines low cytotoxicity with 71.5% cell viability and good interaction with 95.2% of the violacein kept in micellar solution for at least 48 h. [Viol-([C16Him]-S)] complex was used to develop an efficient hybrid solid lipid nanoparticle (SLN) carrier based on myristyl myristate and poloxamer 188 and tailored with folate to target cancer cells. Cellular SLN uptake was evaluated with fluorescent DiOC18 on A549, HCT-116, and HeLa cell lines expressing or not the folate receptor. The results showed fivefold incorporation of Viol nanoparticles in HCT-116 and HeLa cell cultures, displaying a high level of folate receptor. Biophysical characterization of the hybrid solid lipid carrier containing Viol was performed by dynamic light scattering, Fourier transform infrared, X-ray diffraction and X-ray photoelectron spectroscopies, and by transmission electron and cryo-transmission microscopies.

Violacein (Viol) is a pigment produced by several Gram-negative bacteria with many bioactivities, such as anticancer, virucide, and antiparasitic.  相似文献   
30.
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