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   3092篇
  免费   91篇
  国内免费   29篇
耳鼻咽喉   107篇
儿科学   161篇
妇产科学   20篇
基础医学   241篇
口腔科学   112篇
临床医学   166篇
内科学   497篇
皮肤病学   49篇
神经病学   267篇
特种医学   112篇
外科学   251篇
综合类   148篇
预防医学   271篇
眼科学   382篇
药学   303篇
  2篇
中国医学   69篇
肿瘤学   54篇
  2024年   3篇
  2023年   130篇
  2022年   172篇
  2021年   267篇
  2020年   201篇
  2019年   243篇
  2018年   217篇
  2017年   106篇
  2016年   71篇
  2015年   52篇
  2014年   276篇
  2013年   172篇
  2012年   165篇
  2011年   226篇
  2010年   163篇
  2009年   123篇
  2008年   105篇
  2007年   86篇
  2006年   69篇
  2005年   73篇
  2004年   31篇
  2003年   31篇
  2002年   13篇
  2001年   19篇
  2000年   22篇
  1999年   26篇
  1998年   9篇
  1997年   9篇
  1996年   7篇
  1995年   7篇
  1994年   10篇
  1993年   5篇
  1992年   8篇
  1991年   6篇
  1990年   8篇
  1989年   4篇
  1988年   7篇
  1987年   4篇
  1985年   18篇
  1984年   15篇
  1983年   7篇
  1982年   3篇
  1981年   6篇
  1980年   3篇
  1979年   3篇
  1977年   3篇
  1976年   1篇
  1975年   3篇
  1973年   1篇
  1969年   1篇
排序方式: 共有3212条查询结果,搜索用时 15 毫秒
21.
目的 探讨冠心病高危人群颈动脉内中膜厚度的离散度变化及相关影响因素.方法 利用计算机自动识别技术,以每一像素为长度,自动计算出颈动脉内中膜厚度的最大值( CIMT-max)、均值( CIMTmean)、标准差(CIMTSD)并与各种高危因素进行相关分析.结果 CIMTmax、CIMTmean、CIMTSD在高危组分别为(0.810±0.101)、(0.631±0.090)、(0.091±0.070)mm,在对照组分别为(0.704±0.099)、(0.557±0.063)、(0.045±0.014) mm;CIMTmax在0.6、0.7、0.8mm 时,高危组CIMTSD分别为(0.059±0.029)、(0.100 ±0.068)、(0.073.±0.018)mm,对照组分别为(0.041±0.015)、(0.050±0.013)、(0.042±0.013)mm; CIMTmean在0.50 ~0.69 mm时,高危组CIMTSD分别为(0.069±0.021)、(0.084±0.055) mm,对照组分别为(0.045±0.011)、(0.050±0.017) mm (P<0.05);CIMTSD与血清超敏C-反应蛋白、甘油三脂、糖化血红蛋白、总胆固醇、低密度脂蛋白,收缩压、舒张压、吸烟等危险因素的相关性较CIMTmax、CIMTmean更好.结论 CIMTSD比CIMTmax、CIMTmean更能反映早期动脉粥样硬化.  相似文献   
22.

Objective

Thoracic endovascular aortic repair (TEVAR) has demonstrated encouraging results and is gaining increasing acceptance as a treatment option for aortic aneurysms and dissections. Yet, its role in managing proximal aortic pathologies is unknown—this is important because in proximal (Stanford type A) aortic dissections, 10% to 30% are not accepted for surgery and 30% to 50% are technically amenable for TEVAR. We describe our case series of type A aortic dissections treated by using TEVAR.

Methods

Between year 2009 and 2016, 12 patients with acute, subacute, or chronic type A aortic dissection with the proximal entry tear located between the coronaries and brachiocephalic artery were treated with TEVAR at 3 centers. Various stent-graft configurations were used to seal the proximal entry tear in the ascending aorta under rapid pacing.

Results

A total of 12 patients (9 male, 3 female), mean age 81 ± 7 years, EuroSCORE II 9.1 ± 4.5, underwent TEVAR for the treatment of type A aortic dissection. Procedural success was achieved in 11 of 12 patients (91.7%). There was 1 minor stroke and 1 intraprocedural death. No additional deaths were reported at 30 days. At 36 months, there were 4 further deaths (all from nonaortic causes). The mean survival of these 4 deceased was 23 months (range 15-36 months). Follow-up computed tomography demonstrated favorable aortic remodeling.

Conclusions

TEVAR is feasible and reveals promising early results in selected patients with type A aortic dissection who are poor candidates for surgical repair. The current iteration of stent-graft technology, however, needs to be adapted to features specific to the ascending aorta.  相似文献   
23.
PurposeHirschsprung Disease (HD) is a common congenital intestinal disorder. While aganglionosis most commonly affects the rectosigmoid colon (rectosigmoid HD), outcomes for patients in which aganglionosis extends to more proximal segments (long-segment HD) remain understudied. This study sought to compare postoperative outcomes among newborns with rectosigmoid and long-segment HD.MethodsThe Nationwide Readmission Database was queried from 2016 to 2018 for newborns with HD. Newborns were stratified into those with rectosigmoid or long-segment HD. Those who received no rectal biopsy or pull-through procedure during their newborn hospitalization were excluded. A propensity score-matched analysis (PSMA) of newborns with either type of HD was constructed utilizing 17 covariates including demographics, comorbidities, and congenital-perinatal conditions.ResultsThere were 1280 newborns identified with HD (82% rectosigmoid HD, 18% long-segment HD). Patients with rectosigmoid HD had higher rates of laparoscopic resections (35% vs. 12%) and less frequently received a concomitant ostomy (14% vs. 84%), both p < 0.001. Patients with long-segment HD were more likely to have a delayed diagnosis (12% vs. 5%) and require multiple bowel operations (19% vs. 4%), both p < 0.001. They experienced higher rates of complications, including small bowel obstructions (10% vs. 1%), infections (45% vs. 20%), and Hirschsprung-associated enterocolitis (11% vs. 5%), all p < 0.001. After PSMA, newborns with long-segment HD were found to have a longer length of stay and higher hospitalization costs.ConclusionNewborns with long-segment HD experience significant delays in diagnosis, surgery, and complications compared to those with rectosigmoid HD. This information should be utilized to improve healthcare delivery for this patient population.Type of StudyRetrospective comparative study.Level of EvidenceIII.  相似文献   
24.
25.
鼻内镜下鼻中隔成形术临床应用观察   总被引:1,自引:0,他引:1  
目的探讨鼻内镜下鼻中隔成形术的优点.方法鼻内镜下行鼻中隔成形术50例,其中高位和后段偏曲6例.结果50例均一次完成手术,偏曲的鼻中隔均获得彻底矫正.手术时间30~72 min,平均48 min,偏进的鼻中隔获得彻底矫正,随访6~9个月,平均7.1月,治愈45例(90%),好转5例(10%).无鼻中隔血肿、脓肿、穿孔、鼻腔粘连、鼻梁塌陷等并发症发生.结论鼻内镜下鼻中隔成形术,手术时间短,术中出血少,疼痛轻,术后并发症少,可同期行鼻窦手术,完全可以取代传统的鼻中隔黏膜下切除术.  相似文献   
26.
27.
PurposeTo report the computed tomography (CT) features of pancreatic acinar cell carcinoma (ACC) and identify CT features that may help discriminate between pancreatic ACC and pancreatic ductal adenocarcinoma (PDA).Materials and methodsThe CT examinations of 20 patients (13 men, 7 women; mean age, 66.5 ± 10.7 [SD] years; range: 51–88 years) with 20 histopathologically proven pancreatic ACC were reviewed. CT images were analyzed qualitatively and quantitatively and compared to those obtained in 20 patients with PDA. Comparisons were performed using univariate analysis with a conditional logistic regression model.ResultsPancreatic ACC presented as an enhancing (20/20; 100%), oval (15/20; 75%), well-delineated (14/20; 70%) and purely solid (13/20; 65%) pancreatic mass with a mean diameter of 52.6 ± 28.0 (SD) mm (range: 24–120 mm) in association with visible lymph nodes (14/20; 70%). At univariate analysis, well-defined margins (Odds ratio [OR], 7.00; P = 0.005), nondilated bile ducts (OR, 9.00; P = 0.007), visible lymph nodes (OR, 4.33; P = 0.028) and adjacent organ involvement (OR, 5.67; P = 0.02) were the most discriminating CT features to differentiate pancreatic ACC from PDA. When present, lymph nodes were larger in patients with pancreatic ACC (14 ± 4.8 [SD]; range: 7–25 mm) than in those with PDA (8.8 ± 4.1 [SD]; range: 5–15 mm) (P = 0.039).ConclusionOn CT, pancreatic ACC presents as an enhancing, predominantly oval and purely solid pancreatic mass that most frequently present with no bile duct dilatation, no visible lymph nodes, no adjacent organ involvement and larger visible lymph nodes compared to PDA.  相似文献   
28.
PurposeTo determine inter-reader agreement in categorizing hepatocellular carcinoma (HCC) treated with locoregional therapy using the Liver Imaging Reporting and Data System (LI-RADS) treatment response (LR-TR) algorithm.Materials and methodsA total of 93 patients with a total of 112 HCC nodules that were treated using thermal ablation or transarterial chemoembolization were prospectively included. There were 79 men and 14 women with a mean age of 55 ± 2.6 (SD) years (range: 48–63 years). All patients underwent magnetic resonance imaging (MRI) examination of the liver and MR images were analyzed by two independent observers. Treated HCC nodules were categorized into four groups according to LR-TR scoring system including: (i) LR-TR non-evaluable (treated, response not evaluable); (ii) LR-TR nonviable (treated, probably or definitively not viable); (iii) LR-TR equivocal (treated, equivocally viable) and (iv) LR-TR viable (treated, probably or definitively viable). The inter-observer agreement in LR-TR categorization was assessed using the kappa statistics.ResultsThere was excellent inter-observer agreement between the two reviewers for overall treated HCC according to LR-TR algorithm (kappa = 0.938; 95% CI: 0.89–1.00; P = 0.001) with 97.31% agreement. The LR-TR categories by both reviewers were non-viable (77/112; 69.6% and 76/112; 67.9%), viable (30/112; 26.8% and 32/112; 27.7%) and equivocal (5/112; 4.4% and 4/112; 3.6%). There was excellent inter-observer agreement for LR-TR nonviable (kappa = 0.938; 95% CI: 0.87–1.0; P = 0.001) with 97.3% agreement, LR-TR viable (kappa = 0.955; 95% CI: 0.89–1.00; P = 0.001) with 98.2% agreement and good inter-observer agreement for LR-TR equivocal (kappa = 0.700; 95% CI: 0.28–1.0; P = 0.001) with 97.3% agreement.ConclusionLR-TR algorithm conveys high degrees of inter-observer agreement for the evaluation of treatment response of HCC after thermal ablation and transarterial chemoembolization.  相似文献   
29.
PurposeTo compare morphological imaging features and CT texture histogram parameters between grade 3 pancreatic neuroendocrine tumors (G3-NET) and neuroendocrine carcinomas (NEC).Materials and methodsPatients with pathologically proven G3-NET and NEC, according to the 2017 World Health Organization classification who had CT and MRI examinations between 2006-2017 were retrospectively included. CT and MRI examinations were reviewed by two radiologists in consensus and analyzed with respect to tumor size, enhancement patterns, hemorrhagic content, liver metastases and lymphadenopathies. Texture histogram analysis of tumors was performed on arterial and portal phase CT images. images. Morphological imaging features and CT texture histogram parameters of G3-NETs and NECs were compared.ResultsThirty-seven patients (21 men, 16 women; mean age, 56 ± 13 [SD] years [range: 28-82 years]) with 37 tumors (mean diameter, 60 ± 46 [SD] mm) were included (CT available for all, MRI for 16/37, 43%). Twenty-three patients (23/37; 62%) had NEC and 14 patients (14/37; 38%) had G3-NET. NECs were larger than G3-NETs (mean, 70 ± 51 [SD] mm [range: 18 - 196 mm] vs. 42 ± 24 [SD] mm [range: 8 - 94 mm], respectively; P = 0.039), with more tumor necrosis (75% vs. 33%, respectively; P = 0.030) and lower attenuation on precontrast (30 ± 4 [SD] HU [range: 25-39 HU] vs. 37 ± 6 [SD] [range: 25-45 HU], respectively; P = 0.002) and on portal venous phase CT images (75 ± 18 [SD] HU [range: 43 - 108 HU] vs. 92 ± 19 [SD] HU [range: 46 - 117 HU], respectively; P = 0.014). Hemorrhagic content on MRI was only observed in NEC (P = 0.007). The mean ADC value was lower in NEC ([1.1 ± 0.1 (SD)] × 10−3 mm2/s [range: (0.91 - 1.3) × 10−3 mm2/s] vs. [1.4 ± 0.2 (SD)] × 10−3 mm2/s [range: (1.1 - 1.6) × 10−3 mm2/s]; P = 0.005). CT histogram analysis showed that NEC were more heterogeneous on portal venous phase images (Entropy-0: 4.7 ± 0.2 [SD] [range: 4.2-5.1] vs. 4.5 ± 0.4 [SD] [range: 3.7-4.9]; P = 0.023).ConclusionPancreatic NECs are larger, more frequently hypoattenuating and more heterogeneous with hemorrhagic content than G3-NET on CT and MRI.  相似文献   
30.
著名语言学家穆卡洛夫斯基认为,诗歌语言的精髓在于对常规语言的违反,这种违反使得诗歌语言成为可能,没有变异,就没有诗歌。变异可分为语音变异,词汇变异,语法变异,语义变异,书写变异等,其中书写变异形式多样,有特殊的表现力。书写变异的巧妙运用,使诗歌达到前景化,能增强诗歌的美学效果,不仅吸引读者产生强烈的阅读兴趣,而且留下深刻的印象和记忆。  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