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   21664篇
  免费   1802篇
  国内免费   645篇
耳鼻咽喉   244篇
儿科学   429篇
妇产科学   474篇
基础医学   2723篇
口腔科学   350篇
临床医学   1705篇
内科学   4729篇
皮肤病学   409篇
神经病学   1129篇
特种医学   358篇
外国民族医学   2篇
外科学   2875篇
综合类   2717篇
一般理论   1篇
预防医学   1160篇
眼科学   233篇
药学   2198篇
  4篇
中国医学   739篇
肿瘤学   1632篇
  2023年   370篇
  2022年   521篇
  2021年   1043篇
  2020年   1083篇
  2019年   1415篇
  2018年   1474篇
  2017年   935篇
  2016年   670篇
  2015年   826篇
  2014年   1397篇
  2013年   1306篇
  2012年   1165篇
  2011年   1365篇
  2010年   1116篇
  2009年   936篇
  2008年   958篇
  2007年   976篇
  2006年   803篇
  2005年   714篇
  2004年   689篇
  2003年   631篇
  2002年   422篇
  2001年   329篇
  2000年   307篇
  1999年   271篇
  1998年   358篇
  1997年   292篇
  1996年   190篇
  1995年   177篇
  1994年   139篇
  1993年   100篇
  1992年   99篇
  1991年   79篇
  1990年   52篇
  1989年   54篇
  1988年   60篇
  1987年   39篇
  1986年   42篇
  1985年   92篇
  1984年   91篇
  1983年   63篇
  1982年   76篇
  1981年   75篇
  1980年   73篇
  1979年   68篇
  1978年   52篇
  1977年   36篇
  1976年   17篇
  1975年   19篇
  1974年   17篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
目的探讨脂蛋白a[Lp(a)]联合单核细胞/高密度脂蛋白胆固醇(HDL-C)比值(MHR)在非ST段抬高型急性冠脉综合征(NSTE-ACS)患者冠状动脉(冠脉)病变严重程度及预后中的评估及其价值。方法选择2020年3月至2021年3月安徽医科大学第一附属医院符合纳入标准的NSTE-ACS患者(n=310),依据冠脉造影结果进行Gensini评分,以Gensini积分的第3四分位数(QU=38)为切点,分为高危组(QU≥38,n=74)和非高危组(QU<38,n=236),比较其一般资料,并使用Logistic回归分析Lp(a)、MHR与冠脉病变严重程度的相关性;使用ROC曲线评估Lp(a)联合MHR评估冠脉病变严重程度及预后的价值。结果高危组和非高危组患者性别、吸烟史、高血压病、糖尿病、高胆固醇血症、肾功能不全等病史、他汀药物应用发生率差异无统计学意义(P>0.05),但高危组患者年龄、血Lp(a)水平和MHR均显著高于非高危组(P<0.01)。Spearman相关分析发现,Lp(a)和MHR分别与Gensini评分呈正相关(r=0.316,P<0.05;r=0.715,P<0.05)。Logistic多因素二元回归分析示,Lp(a)、年龄和MHR是冠脉高危病变的独立危险因素(P<0.01,P<0.05)。ROC曲线分析示,Lp(a)和MHR联合检测对冠脉高危病变评估的AUC(0.854),分别大于Lp(a)和MHR单独检测的AUC(0.852、0.754);联合评估的敏感度73.0%,高于单独检测Lp(a)的55.6%,但低于MHR的82.4%;联合评估的特异度85.6%,高于Lp(a)及MHR单独检测(84.1%、61.9%)。ROC曲线分析示,Lp(a)和MHR联合对NSTE-ACS患者不良预后评估的AUC(0.800),分别大于Lp(a)和MHR单独检测的AUC(0.781、0.739);联合评估患者预后的敏感度为72.2%,高于Lp(a)及MHR单独检测(66.7%、66.7%);联合评估的特异度为81.9%,高于MHR单独检测的80.9%,但低于Lp(a)单独检测的84.8%。结论异常升高的血Lp(a)水平联合MHR对NSTE-ACS患者冠脉病变的严重程度和不良预后具有较高的判断价值。  相似文献   
2.
3.
4.
本文报道了1例食管主动脉瘘患者的诊治情况,详细记录了患者的内镜及CT表现,并对患者食管主动脉瘘病变的内镜超声特征做了详细的描述。  相似文献   
5.
Background: Triple negative breast cancer (TNBC) is associated with poor prognosis, aggressive phenotype(s) of tumours, partial chemotherapy response, and lack of clinically proven therapies. MicroRNAs (miRNAs) can target and modulate key genes that are involved in TNBC chemotherapy. Deregulated miRNA expression is highly involved in anti-cancer drug resistance phenotype and thus, miRNAs tend to be promising candidates for prediction of chemotherapy response and recurrence. Aim: This study aimed to investigate the expression levels of selected miRNAs (miR-21, miR-27b, miR-34a, miR-182, miR-200c and miR-451a) in cancerous and normal adjacent tissues of TNBC patients and to correlate with the clinicopathological data. Methods: Forty-one (41) FFPE tissue block of histopathologically confirmed TNBC patients was collected. Total RNA from the cancerous and adjacent non-cancerous tissues were isolated, transcribed, and pre-amplified. The relative expression level of miRNAs in tumour and normal adjacent tissues of TNBC patients was analysed using qRT-PCR. Results: Out of six miRNAs studied, the relative expression of miR-27b and miR-451a were found to be significantly lower in cancerous as compared to normal adjacent tissues of TNBC patients. In addition, a significant down regulation of miR-451a was also observed in infiltrating ductal carcinoma subtype, stages I and II, in both grade II and III, premenopausal and postmenopausal as well as in those with positive axillary lymph node metastases. Conclusion: The results suggest the possible utilization of miR-27b and miR-451a expression levels as potential predictive risk markers for TNBC patients undergoing TAC chemotherapy.  相似文献   
6.
目的 旨在探究涤痰活血舒痹汤(Ditan Huoxue Shubi Decoction,DHS)与microRNA-148a(miR-148a)的调控关系以及其在心肌缺血再灌注损伤中的分子作用机制。方法 将H9c2细胞培养后分为对照组、缺氧/复氧(hypoxia/reoxygenation,H/R)组、H/R+空白血清组、H/R+DHS含药血清组、H/R+DHS含药血清+miR-148a拮抗剂组、H/R+DHS含药血清+OE-NC组和H/R+DHS含药血清+TXNIP过表达质粒组。采用CCK-8检测H9c2细胞增殖,TUNEL染色检测H9c2细胞凋亡。运用Western blot检测H9c2细胞中凋亡和自噬相关蛋白表达。利用 qRT-PCR检测miR-148a的表达。Western blot检测靶蛋白TXNIP的表达。结果 与对照组比较,H/R组H9c2细胞活力下降[(97.75±5.58)%比(69.72±8.80)%,P < 0.01]、细胞凋亡和自噬水平上升。与H/R+空白血清组比较,H/R+DHS含药血清组miRNA-148a表达上调[(1.04±0.25)比(2.45±0.39),P < 0.01],H9c2细胞活力增加[(97.75±7.94)%比(135.98±10.45)%,P < 0.01]并且细胞凋亡和自噬显著下降(P < 0.05)。H/R+DHS含药血清+miR-148a拮抗剂组细胞内miRNA-148a表达下调[(2.18±0.25)比(0.66±0.12),P < 0.001],同时靶基因TXNIP表达上调。与H/R+DHS含药血清+OE-NC组比较,H/R+DHS含药血清+TXNIP过表达质粒组的TXNIP表达水平、细胞凋亡和自噬水平显著上升(P < 0.05)。结论 涤痰活血舒痹汤能够减轻H/R引起的心肌细胞H9c2细胞的损伤,其作用机制可能是通过升高miR-148a水平而减低TXNIP表达来降低损伤的心肌细胞自噬和凋亡水平来实现的。  相似文献   
7.
Introduction and objectivesIonizing radiation exposure in catheter ablation procedures carries health risks, especially in pediatric patients. Our aim was to compare the safety and efficacy of catheter ablation guided by a nonfluoroscopic intracardiac navigation system (NFINS) with those of an exclusively fluoroscopy-guided approach in pediatric patients.MethodsWe analyzed catheter ablation results in pediatric patients with high-risk accessory pathways or supraventricular tachycardia referred to our center during a 6-year period. We compared fluoroscopy-guided procedures (group A) with NFINS guided procedures (group B).ResultsWe analyzed 120 catheter ablation procedures in 110 pediatric patients (11 ± 3.2 years, 70% male); there were 62 procedures in group A and 58 in group B. We found no significant differences between the 2 groups in procedure success (95% group A vs 93.5% group B; P = .53), complications (1.7% vs 1.6%; P = .23), or recurrences (7.3% vs 6.9%; P = .61). However, fluoroscopy time (median 1.1 minutes vs 12 minutes; P < .0005) and ablation time (median 96.5 seconds vs 133.5 seconds; P = .03) were lower in group B. The presence of structural heart disease was independently associated with recurrence (P = .03).ConclusionsThe use of NFINS to guide catheter ablation procedures in pediatric patients reduces radiation exposure time. Its widespread use in pediatric ablations could decrease the risk of ionizing radiation.  相似文献   
8.
Background and aimsAlthough antithrombotic treatments are established for coronary artery disease (CAD), they increase the bleeding risk, especially in malnourished patients. The total thrombus-formation analysis system (T-TAS) is useful for the assessment of thrombogenicity in CAD patients. Here, we examined the relationships among malnutrition, thrombogenicity and 1-year bleeding events in patients undergoing percutaneous coronary intervention (PCI).Methods and resultsThis was a retrospective analysis of 300 consecutive CAD patients undergoing PCI. Blood samples obtained on the day of PCI were used in the T-TAS to compute the thrombus formation area under the curve. We assigned patients to two groups based on the geriatric nutritional risk index (GNRI): 102 patients to the lower GNRI group (≤98), 198 patients to the higher GNRI group (98<). The primary endpoint was the incidence of 1-year bleeding events defined by Bleeding Academic Research Consortium criteria types 2, 3, or 5. The T-TAS levels were lower in the lower GNRI group than in the higher GNRI group. Kaplan-Meier analysis showed worse 1-year bleeding event-free survival in the lower GNRI group compared with the higher GNRI group. The combined model of the GNRI and the Academic Research Consortium for High Bleeding Risk (ARC-HBR) had good calibration and discrimination for bleeding risk prediction. In addition, having a lower GNRI and ARC-HBR positivity was associated with 1-year bleeding events.ConclusionA lower GNRI could reflect low thrombogenicity evaluated by the T-TAS and determine bleeding risk in combination with ARC-HBR positivity.  相似文献   
9.
目的观察病毒性心肌炎(VMC)病儿血浆外泌体微小RNA(miR)-148a的水平并分析其意义。方法选择2017年9月至2019年6月郑州大学附属儿童医院收治的VMC病儿112例纳入研究组,另选取同期门诊健康体检正常儿童112例为对照组,实时荧光定量PCR(RT-qPCR)检测血浆外泌体miR-148a水平,酶联免疫吸附测定(ELISA)检测血浆外泌体心肌肌钙蛋白I(cTnI),采用自动化生化仪检测血浆外泌体肌酸激酶同工酶(CK-MB)水平、超敏C反应蛋白(hs-CRP)水平。采用Pearson相关性分析检验VMC病儿血浆外泌体miR-148a与cTnI、CK-MB、hs-CRP水平的相关性。绘制受试者工作特征曲线(ROC)分析血浆外泌体miR-148a对VMC的诊断价值。结果血浆外泌体在透射电镜下呈大小不等、直径约100 nm典型圆形或椭圆形囊泡结构。与对照组比较,研究组血浆外泌体miR-148a水平[(1.01±0.12)比(5.34±1.06)]、血浆cTnI、CK-MB、hs-CRP水平均增加(均P<0.001)。VMC病儿血浆外泌体miR-148a与血浆cTnI、CK-MB、hs-CRP水平均呈正相关(r=0.62、0.64、0.49,均P<0.001)。血浆外泌体miR-148a及血浆cTnI、CK-MB、hs-CRP诊断早期VMC的曲线下面积(AUC)分别为0.94、0.94、0.83、0.86,截断值分别为1.87、0.19 μg/L、56.45 U/L、2.06 mg/L,灵敏度分别为94.60%、92.90%、84.80%、83.90%,特异度分别为92.90%、94.60%、83.90%、83.90%。血浆外泌体miR-148a与血浆cTnI诊断早期VMC的效能一致,均优于血浆CK-MB、hs-CRP。结论VMC病儿血浆外泌体miR-148a水平上调,可能对VMC有一定诊断价值。  相似文献   
10.
In this fifth phase of development, the contents of the Spanish Asthma Management Guidelines (GEMA), which include versions 5.0 and 5.1, have undergone a thorough review. The aim here is to set the main changes in context. These could be summarized as follows: DIAGNOSIS: new FENO cut-off and severity classification based on treatment needed to maintain control; INTERMITTENT ASTHMA: a more restrictive concept and treatment extended to include a glucocorticoid/adrenergic combination as needed; MILD ASTHMA: glucocorticoid/adrenergic therapy as needed as an alternative in case of low therapeutic adherence to conventional fixed-dose steroids; SEVERE ASTHMA: readjustment of phenotypes, incorporation of triple therapy in a single inhaler, and criteria for selection of a biologic in severe uncontrolled asthma; OTHERS: specific scoring in childhood asthma, incorporation of certain organizational aspects (care circuits, asthma units, telemedicine), new sections on COVID-19 and nasal polyposis.  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