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   24564篇
  免费   2123篇
  国内免费   580篇
耳鼻咽喉   422篇
儿科学   534篇
妇产科学   468篇
基础医学   2441篇
口腔科学   322篇
临床医学   2409篇
内科学   3556篇
皮肤病学   562篇
神经病学   721篇
特种医学   887篇
外国民族医学   14篇
外科学   4516篇
综合类   3144篇
现状与发展   2篇
预防医学   949篇
眼科学   79篇
药学   1281篇
  16篇
中国医学   247篇
肿瘤学   4697篇
  2024年   52篇
  2023年   442篇
  2022年   800篇
  2021年   1051篇
  2020年   1028篇
  2019年   968篇
  2018年   957篇
  2017年   939篇
  2016年   958篇
  2015年   918篇
  2014年   1635篇
  2013年   1565篇
  2012年   1384篇
  2011年   1529篇
  2010年   1185篇
  2009年   1222篇
  2008年   1324篇
  2007年   1367篇
  2006年   1074篇
  2005年   963篇
  2004年   817篇
  2003年   684篇
  2002年   564篇
  2001年   470篇
  2000年   402篇
  1999年   360篇
  1998年   309篇
  1997年   236篇
  1996年   198篇
  1995年   187篇
  1994年   196篇
  1993年   148篇
  1992年   138篇
  1991年   163篇
  1990年   117篇
  1989年   100篇
  1988年   102篇
  1987年   103篇
  1986年   83篇
  1985年   89篇
  1984年   73篇
  1983年   53篇
  1982年   69篇
  1981年   47篇
  1980年   43篇
  1979年   39篇
  1978年   30篇
  1977年   37篇
  1976年   20篇
  1975年   11篇
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
1.
2.
Patients undergoing sentinel node biopsy (SLNB) for early oral squamous cell carcinoma (OSCC) who harbour occult metastases (pN+ve) may be at greater risk of mortality due to prolonged overall treatment times than those identified as pN+ve on elective neck dissection (ELND). A retrospective comparative survival analysis was therefore undertaken to test this hypothesis. Patients were identified from the South Glasgow multidisciplinary team (MDT) database. Group 1 comprised 38 patients identified as pN+ve, or who were false negative, on sentinel lymph node biopsy (SLNB). Group 2 comprised 146 patients staged pN+ve on ELND. The groups were compared with the Kaplan Meier method and Cox proportional hazards model. In addition, a matched-pair analysis was performed. A unique and specifically designed algorithm was deployed to optimise the pairings. No difference in disease-specific or overall survival was found between the groups. Patients undergoing SLNB as the initial neck staging modality in early OSCC and are identified as pN+ve do not appear to be at a survival disadvantage compared with those staged with ELND.  相似文献   
3.
目的 探讨溶质载体蛋白(SLC)及其受体趋化因子受体7(CCR7)与I期非小细胞肺癌(NSCLC)淋巴结微转移的相关性。方法 选取2019年1月~2020年3月于我院就诊的I期NSCLC患者127例为研究对象,按照淋巴结微转移情况分为对照组92例和转移组35例,所有患者入院后均通过根治术切除病灶,通过免疫组化方式检测病灶中SLC7A11及CCR7含量,并收集患者临床资料、实验室检查资料及影像学检查资料。通过Logistic回归分析评价SLC7A11及CCR7与淋巴结微转移之间的关系。最后通过建立ROC曲线分析两者及其联合检测对NSCLC患者微淋巴结转移的预测价值。结果 两组患者SLC7A11及CCR7表达水平存在显著差异(P<0.05)。转移组患者病灶直径、支气管受累及TLG显著高于对照组(P<0.05)。病灶直径(OR=49.254,95%CI=11.062~507.604)是影响NSCLC淋巴结微转移的独立危险因素(P<0.05)。SLC7A11(OR=8.622)及CCR7(OR=8.709)表达水平是影响NSCLC淋巴结微转移的独立因素(P<0.05)。SLC7A11、CCR7及联合诊断对NSCLC淋巴结微转移具有较好的检测价值(均P<0.05)。联合检测特异度显著高于 SLC7A11及CCR7单独检测(2=7.292,15.125;均P<0.01)。结论 SLC家族的中SLC7A11及其受体CCR7与NSCLC患者微淋巴结转移显著相关。  相似文献   
4.
正目前,临床上对于直肠癌常用的影像评估方法有MRI、螺旋CT、PET-CT、直肠腔内超声(ERUS)等。而MRI作为首选检查方式,对肿瘤位置、浸润深度、淋巴结转移、血管侵犯、环周切缘及周围器官侵犯等方面的评估均具有明显优势~([1-2])。通过MRI诊断淋巴结的方法通常是影像科医师逐层浏览每一幅图像,从中识别淋巴结的形状、界限及密度来判断,这种传统方式耗时较长且存在主观偏倚,导致  相似文献   
5.
BackgroundLymph node recurrences (LNR) from colorectal cancer (CRC) still represent a therapeutic challenge, as standardized recommendations have yet to be established. The aim of this study was to analyze short- and long-term oncological outcomes following resection of LNR from CRC.MethodsAll patients with previously resected CRC who underwent histopathologically confirmed LNR resection in 3 tertiary referral centers between 2010 and 2017 were reviewed. Short- and long-term outcomes were analyzed, mainly recurrence-free and overall survival. Further recurrences following LNR resection were also analyzed.ResultsOverall, 18 patients were included. Primary CRC was left-sided in 16 (89%) patients, staged T3-4 in 15 (83%), N+ in 14 (78%) and presented with synchronous metastases in 8 (43%). Median time interval between primary CRC and LNR resections was 31 months. Performed lymphadenectomies were aortocaval (n = 10), pelvic (n = 7), in hepatic pedicle (n = 3) and mesenteric (n = 1). Four patients had associated liver metastases resection. Three (17%) presented with postoperative complications, of which one Clavien-Dindo 3. Fourteen (78%) patients presented with further recurrences after a mean delay of 9 months, with 36% of patients presenting with early (<6 months) recurrence. Five (36%) patients could undergo secondary recurrence resection and 3 (21%) patients radiotherapy. Median overall survival following LNR resection reached 44 months.ConclusionsCurrent results suggest that LNR resection is feasible and associated with improved survival, in selected patients. Longer time interval between primary CRC resection and LNR occurrence appeared to be a favorable prognostic factor whereas multisite recurrence appeared to be associated with impaired long-term survival.  相似文献   
6.
《Clinical neurophysiology》2020,131(1):259-264
ObjectivesFasciculation potentials (FP) are an important consideration in the electrophysiological diagnosis of ALS. Muscle ultrasonography (MUS) has a higher sensitivity in detecting fasciculations than electromyography (EMG), while in some cases, it is unable to detect EMG-detected fasciculations. We aimed to investigate the differences of FP between the muscles with and without MUS-detected fasciculations (MUS-fas).MethodsThirty-one consecutive patients with sporadic ALS were prospectively recruited and in those, both needle EMG and MUS were performed. Analyses of the amplitude, duration, and number of phases of EMG-detected FPs were performed for seven muscles per patient, and results were compared between the muscles with and without MUS-fas in the total cohort.ResultsThe mean amplitude and phase number of FP were significantly lower in patients with EMG-detected FP alone (0.39 ± 0.25 mV and 3.21 ± 0.88, respectively) than in those with both FP and MUS-fas (1.22 ± 0.92 mV and 3.74 ± 1.39, respectively; p < 0.0001 and p = 0.017, Welch’s t-test).ConclusionSmall FP may be undetectable with MUS. MUS cannot replace EMG in the diagnostic approach for ALS.SignificanceClinicians should use a combination of EMG and MUS for the detection and quantitative analysis of fasciculation in ALS.  相似文献   
7.
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   
8.
9.
目的:比较经鼻导管高流量吸氧(HFNC)与经鼻气道正压通气(nCPAP)在重症毛细支气管炎呼吸支持中的应用价值,为临床治疗方案的选择提供参考。方法:选取2016年12月至2018年12月我院儿科收治的重症毛细支气管炎患儿90例,采用随机数字表法分为观察组和对照组各45例。两组患儿入院后均给予常规综合治疗以保证呼吸道通畅,在此基础上观察组采用HFNC治疗,对照组采用nCPAP治疗,比较两组患儿治疗前和治疗24 h后呼吸频率、经皮血氧饱和度(TcSO2)、呼吸窘迫评分体系(CSS)评分、动脉血氧分压(PaO2)等呼吸相关指标及治疗前后临床症状体征改善情况。结果:两组患儿治疗24 h后呼吸频率、CSS评分均降低,且观察组降低程度更大,TcSO2、PaO2于治疗24 h后升高,观察组升高幅度较对照组明显;治疗后两组患儿咳嗽及肺部湿啰音、肺部炎症情况均改善,观察组症状体征消失时间早于对照组,差异均有统计学意义(P<0.05)。结论:重症毛细支气管炎患儿采用HFNC治疗可明显改善通气功能和临床症状,治疗效果优于nCPAP治疗,可扩大样本量进一步观察。  相似文献   
10.
Objective: Keyes’ two continua model is a useful concept in which mental health and mental illness exist on two separate axes. Based on this model, this study examined the prevalence and correlates of three mental health categories among older adults in China.

Methods: Cross-sectional data were derived from Wave 1 of the Study on Global AGEing and Adult Health. Participants were categorized into complete mental health (CMH), complete mental illness (CMI), and moderate mental health (MMH) groups. Multinomial logistic regressions were used.

Results: The prevalence of CMH, CMI, and MMH in China was 18%, 16%, and 66%, respectively. Being female, unmarried, younger, and feeling unhealthy were more likely to result in placement in the CMI category. Employment, education, and cognitive function were identified as important protective factors of CMH. Age, income, urban or rural residence, and physical function difficulty were associated with all three categories.

Discussion: We demonstrated the utility of the two continua model in identifying mental health needs in Chinese contexts. The findings suggest that future policy reforms and clinical interventions should establish a more comprehensive mental health category as a screening tool nationwide. The promotion of social engagement could play an important role in treating mental illness and improving positive mental health.  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