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   3988篇
  免费   270篇
  国内免费   18篇
耳鼻咽喉   54篇
儿科学   289篇
妇产科学   405篇
基础医学   397篇
口腔科学   117篇
临床医学   323篇
内科学   887篇
皮肤病学   82篇
神经病学   267篇
特种医学   115篇
外科学   581篇
综合类   85篇
一般理论   1篇
预防医学   190篇
眼科学   109篇
药学   209篇
中国医学   11篇
肿瘤学   154篇
  2023年   32篇
  2022年   50篇
  2021年   79篇
  2020年   70篇
  2019年   75篇
  2018年   113篇
  2017年   95篇
  2016年   127篇
  2015年   133篇
  2014年   135篇
  2013年   235篇
  2012年   280篇
  2011年   319篇
  2010年   176篇
  2009年   145篇
  2008年   282篇
  2007年   301篇
  2006年   256篇
  2005年   278篇
  2004年   231篇
  2003年   193篇
  2002年   163篇
  2001年   67篇
  2000年   51篇
  1999年   50篇
  1998年   17篇
  1997年   9篇
  1996年   13篇
  1995年   11篇
  1994年   14篇
  1993年   16篇
  1992年   18篇
  1991年   14篇
  1990年   13篇
  1989年   11篇
  1988年   13篇
  1987年   12篇
  1985年   11篇
  1984年   9篇
  1982年   8篇
  1980年   7篇
  1979年   9篇
  1976年   8篇
  1975年   8篇
  1974年   7篇
  1973年   8篇
  1971年   10篇
  1970年   6篇
  1969年   6篇
  1968年   9篇
排序方式: 共有4276条查询结果,搜索用时 140 毫秒
61.
62.

Pupose  

Obstructive sleep apnea (OSA) is associated with various metabolic disorders, and oxidative stress was suggested to play an important role. In the present study, we aimed to investigate serum adiponectin and oxidative stress markers, especially protein carbonyls, and to evaluate the correlation between these parameters and lipid, insulin and fasting glucose concentrations in OSA patients and controls.  相似文献   
63.
Image quality in non‐contrast‐enhanced (NCE) angiograms is often limited by scan time constraints. An effective solution is to undersample angiographic acquisitions and to recover vessel images with penalized reconstructions. However, conventional methods leverage penalty terms with uniform spatial weighting, which typically yield insufficient suppression of aliasing interference and suboptimal blood/background contrast. Here we propose a two‐stage strategy where a tractographic segmentation is employed to auto‐extract vasculature maps from undersampled data. These maps are then used to incur spatially adaptive sparsity penalties on vascular and background regions. In vivo steady‐state free precession angiograms were acquired in the hand, lower leg and foot. Compared with regular non‐adaptive compressed sensing (CS) reconstructions (CSlow), the proposed strategy improves blood/background contrast by 71.3 ± 28.9% in the hand (mean ± s.d. across acceleration factors 1–8), 30.6 ± 11.3% in the lower leg and 28.1 ± 7.0% in the foot (signed‐rank test, P < 0.05 at each acceleration). The proposed targeted reconstruction can relax trade‐offs between image contrast, resolution and scan efficiency without compromising vessel depiction. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
64.
65.
66.
Xanthelasmas of the upper gastrointestinal tract   总被引:1,自引:0,他引:1  
Background Gastric xanthelasma is a benign and uncommon lesion with a variably reported frequency, while esophageal and duodenal xanthelasmas are quite rare.Methods Seventeen patients who had the diagnosis of xanthelasma in the upper gastrointestinal tract were analyzed retrospectively with respect to their demographic, clinical, endoscopic, and histopathologic features. All lesions suspected as xanthelasma were totally removed by either hot biopsy forceps or a snare with the technique of endoscopic mucosal resection.Results The incidence of upper gastrointestinal xanthelasmas in 7320 patients who had upper gastro-intestinal endoscopy was 0.23%. There were 9 (53%) men and 8 (47%) women, with a median age of 50 years (range, 24–80 years). The most common location of xanthelasmas was the stomach (76%), followed by the esophagus (12%) and duodenum (12%). All lesions were observed as yellow-white colored plaques at endoscopy. Multiple xanthelasmas were detected in 4 patients (24%); in the duodenum in 2, esophagus in 1, and stomach in 1. One patient had xanthelasma within a gastric hyperplastic polyp. The size of the lesion was less than 5mm in diameter in 14 (82%) patients and between 5 and 10mm in diameter in 3 (18%). Thirteen (76%) patients had moderate to severe atrophic gastritis, while the remainder had normal gastric mucosa.Conclusions Xanthelasmas of the upper gastrointestinal tract were mostly located in the stomach in the present series, which includes the second and third reported cases of duodenal xanthelasma, the second case of xanthelasma developed within a hyperplastic gastric polyp, and the fourth and the fifth cases of esophageal xanthelasma.  相似文献   
67.
Three clusters of Chryseobacterium meningosepticum infections in a tertiary health center in July 2006 and January 2007 involving 8 newborns and 5 older children were investigated. The index patient was from the neonatal intensive care unit, and the older patients were from other pediatric wards. Cultures were obtained from the environment and from health care workers' hands as part of an outbreak investigation. C meningosepticum was isolated from hand cultures obtained from a senior resident and from environmental cultures obtained from powdered infant formula, an electrical button, a computer keyboard, phone, a doorknob, and an Ambu bag. Antibiogram typing and enterobacterial repetitive intergenic consensus sequence polymerase chain reaction indicated that all of the isolates were epidemiologically related. Nine patients improved on antimicrobial treatment, and 4 premature infants died after the infection. C meningosepticum is a well-known etiologic agent for nosocomial infections involving newborns and immunocompromised patients. Wet and dry environmental surfaces and equipment may act as a source or play a role in disseminating the microorganism. Outbreaks may be controlled with strong emphasis on infection control measures.  相似文献   
68.
Increased immunoglobulin E response in acute coronary syndromes   总被引:3,自引:0,他引:3  
Erdogan O  Gul C  Altun A  Ozbay G 《Angiology》2003,54(1):73-79
The role of inflammation and mast cell activation has been implicated in atherosclerotic plaque destabilization and rupture. To investigate the role of immunoglobulin E (IgE) in acute coronary syndrome, a prospective clinical study was conducted in patients with acute myocardial infarction (AMI), unstable angina pectoris (UAP), stable angina pectoris (SAP), and healthy controls. IgE levels were serially measured and compared in consecutive patients with AMI (n = 16) and UAP (n = 14) on days 1, 3, 7, 21 after admission and 3 months later and only once in stable angina pectoris (n = 15) and healthy controls (n = 14). In addition, blood eosinophil and basophil levels on admission were measured in all groups and compared. Initial IgE levels determined at admission in patients with AMI, UAP, and SAP were significantly higher than levels in the control group (p = 0.002). Initial high IgE level in AMI on day 1 increased to a peak by day 7 (p = 0.024), then gradually decreased by day 21 and at 3 months (p = 0.052). High IgE level in UAP persisted by day 7 and gradually decreased by day 21 and 3 months (p = 0.037 and p = 0.018, respectively). Blood eosinophil count on admission was significantly higher in UAP than in the control group (p = 0.005). Basophil levels of both AMI and UAP groups on admission were found to be elevated as opposed to control group (p = 0.02 and p = 0.012, respectively). This study demonstrates that the level of IgE significantly increased during the acute phase of acute coronary syndromes and gradually decreased, supporting the role of acute inflammatory response and mast cell involvement in plaque rupture.  相似文献   
69.
OBJECTIVES: The vena contracta is the narrowest region of the regurgitant or stenotic jet just downstream the orifice and reflects the size of that orifice. This study was performed to assess the accuracy of the vena contracta width (VCW) in evaluating the severity of mitral stenosis (MS) and to compare the mitral valve area (MVA) determined by VCW with MVAs obtained by other more traditional echocardiographic methods. METHODS: We studied 59 patients (43 females, 42 +/- 14 years) with MS. VCW was measured in the apical four chamber view by Doppler color flow mapping. The largest diameter of the VCW during diastole was measured for at least three cardiac cycles and averaged. MVA was calculated from the following equation: pir(2), where r = VCW/2. MVA was also determined by planimetry, the pressure half-time method, and by the Gorlin formula. RESULTS: In this study, the width of the vena contracta ranged from 0.89 to 1.73 cm (mean 1.30 +/- 0.21). MVA, calculated based on the VCW, ranged from 0.63 to 2.35 cm(2) (mean 1.36 +/- 0.41). MVA by VCW (1.36 +/- 0.41 cm(2)) showed good correlations with three comparative techniques: (1) the cross-sectional area by planimetry (1.35 +/- 0.36 cm(2), mean difference = 0.21 +/- 0.16 cm(2), y = 0.91x + 0.14, r = 0.79, SEE = 0.26 cm(2), p < 0.001); (2) the area derived from the Doppler pressure half-time (1.27 +/- 0.32 cm(2), mean difference = 0.22 +/- 0.19 cm(2), y = 0.97x + 0.13, r = 0.76, SEE = 0.27 cm(2), p < 0.001), and (3) the area derived from the Gorlin equation in the 18 patients who underwent catheterization (1.27 +/- 0.35 cm(2), mean difference = 0.19 +/- 0.16, y = 0.98x + 0.05, r = 0.81, SEE = 0.26 cm(2), p < 0.001). CONCLUSIONS: These findings suggest that Doppler color flow imaging of the MS jet in the vena contracta can provide an accurate estimation of MVA and appears to be potentially applicable in the assessment of the severity of MS.  相似文献   
70.
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