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   2780篇
  免费   176篇
  国内免费   56篇
耳鼻咽喉   48篇
儿科学   75篇
妇产科学   98篇
基础医学   365篇
口腔科学   566篇
临床医学   187篇
内科学   295篇
皮肤病学   17篇
神经病学   154篇
特种医学   87篇
外科学   289篇
综合类   324篇
预防医学   200篇
眼科学   155篇
药学   68篇
  2篇
中国医学   26篇
肿瘤学   56篇
  2024年   1篇
  2023年   39篇
  2022年   47篇
  2021年   121篇
  2020年   110篇
  2019年   106篇
  2018年   104篇
  2017年   96篇
  2016年   95篇
  2015年   101篇
  2014年   173篇
  2013年   180篇
  2012年   142篇
  2011年   155篇
  2010年   131篇
  2009年   132篇
  2008年   149篇
  2007年   117篇
  2006年   111篇
  2005年   117篇
  2004年   99篇
  2003年   84篇
  2002年   71篇
  2001年   57篇
  2000年   51篇
  1999年   69篇
  1998年   63篇
  1997年   51篇
  1996年   33篇
  1995年   41篇
  1994年   25篇
  1993年   28篇
  1992年   22篇
  1991年   18篇
  1990年   6篇
  1989年   7篇
  1988年   4篇
  1987年   8篇
  1986年   6篇
  1985年   6篇
  1984年   9篇
  1983年   5篇
  1982年   5篇
  1981年   4篇
  1980年   5篇
  1979年   2篇
  1978年   3篇
  1977年   1篇
  1976年   1篇
  1973年   1篇
排序方式: 共有3012条查询结果,搜索用时 15 毫秒
101.
介绍了重庆西永垃圾转运站的建筑背景、工程概况及工程总体设计方案,具体阐述了转运工艺、设备配置、车间工艺布置、除臭、渗沥液处理等设计内容,并论述了该项目特点及创新性。  相似文献   
102.
Objectives. This report evaluates the use of Gianturco coils to close large patent ductus arteriosus (PDAs) (≥3.5 mm) and describes transvenous delivery of 0.052-in. (0.132-cm) Gianturco coils.

Background. Coil closure of PDAs has become increasingly popular. However, the technique has significant limitations when used to close large PDAs. This report evaluates patient characteristics, PDA anatomy, hemodynamic variables, delivery technique and coil geometry to determine predictors of success.

Methods. Between January 1995 and January 1997, 16 of 118 patients undergoing catheterization for PDA closure were found to have large PDAs. Their median age and weight were 14 months (range 3 months to 43 years) and 8.5 kg (range 3.5 to 73), respectively. The mean PDA diameter was 4.3 mm (range 3.5 to 5.9). Closure of PDAs was attempted using transcatheter delivery of 0.038-in. (0.096-cm) and 0.052-in. coils. Differences in clinical, anatomic, hemodynamic and technical variables between successes and failures were compared.

Results. Eleven (69%) of 16 patients had successful closure of their PDA. Failures occurred only in patients <8 months of age with an indexed PDA diameter >7 mm/m and a pulmonary/systemic flow ratio ≥2.8:1. Use of 0.052-in. coils tended to reduce the incidence of embolization and the number of coils needed for closure.

Conclusions. Patients >8 months of age can have successful closure of large PDAs with currently available Gianturco coils. The 0.052-in. Gianturco coils can be used safely to close large PDAs in infants as small as 6 kg. Increased experience and improved coil design may improve closure rates of large PDAs in infants.  相似文献   

103.
ObjectivesTo compare neuromuscular control and hop performance between youth and adult male and female football players.DesignCross-sectional study.Participants119 youth players (13–16 years; 68 males) and 88 adult players (17–26 years; 44 males).Main outcome measuresNeuromuscular control assessed with drop vertical jump (DVJ) and tuck jump assessment (TJA). Hop performance assessed with single-leg hop for distance and side hop.ResultsAdult females had smaller normalized knee separation distances (NKSD) during DVJ at initial contact (77.9 ± 18.5 vs. 86.1 ± 11.0, p = 0.010) and at maximum knee flexion (59.7 ± 23.4 vs.74.1 ± 18.1, p = 0.001) compared to youth females. TJA revealed more technique errors in youths compared to adults (males 10 (8–11) vs. 8 (7–10); females 11 (9–12) vs. 9 (8–11), p < 0.05). Youths demonstrated inferior hop performance (males single-leg hop 142 ± 18 vs. 163 ± 17, side hop 41 ± 12 vs. 52 ± 12, p < 0.001; females side hop 32 ± 10 vs. 38 ± 14, p < 0.05).ConclusionsYouth players demonstrated reduced neuromuscular control during TJA and inferior hop performance compared to adult players. Adult female players demonstrated greater knee valgus during DVJ compared to youth female players.  相似文献   
104.
BACKGROUND: Due to the absence of differential guidelines for heart failure with tachyarrhythmia, it is difficult to diagnose tachycardia-induced cardiomyopathy (TIC) at the initial visit. Furthermore, clinical outcomes of rate versus rhythm control in TIC are unclear. HYPOTHESIS: Because the etiology of TIC is different from dynamic cardiomyoplasty (DCMP), differential parameters may be present. METHODS: We assessed 21 patients with TIC (15 men; mean age, 50+/-14 years) and 21 control patients with idiopathic DCMP. We assessed clinical courses, echocardiographic parameters, as well as outcomes by treatment. RESULTS: In the TIC group, the related tachyarrhythmias were atrial fibrillation (n=12), atrial flutter (n=5), atrial tachycardia (n=3) and paroxysmal supraventricular tachycardia (n=1). After treatment, all patients became asymptomatic and the ejection fraction (EF) improvement (DeltaEF>or=15%) was observed in all patients (left ventricular ejection fraction [LVEF], 30+/-11%initial versus 58+/-6%last). In the idiopathic DCMP group, no patient showed EF improvement (EF increase相似文献   
105.
The aim of the study was to investigate the possible association between polymorphisms of HPA axis genes-CRHR1 (corticotrophin-releasing hormone receptor), NR3C1 (glucocorticoid receptor) and AVPR1B (arginine vasopressin receptor) and dimensions of bipolar disorder assessed by OPCRIT.  相似文献   
106.

Background

We examined the association of cognitive vulnerability to depression with changes in homogeneous measures of depressive symptoms.

Methods

Baseline and 1-year follow-up data were obtained from 2981 participants of the Netherlands study of depression and anxiety. Multivariate regression analyses were carried out on cognitive reactivity, locus of control and implicit and explicit self-depressive associations in combination with negative life events. The purpose of this analysis was to predict changes on the mood/cognition and anxiety/arousal subscales of the inventory of depressive symptomatology - self report.

Results

Cognitive reactivity, locus of control and explicit self-depressive associations were independently associated with changes in depressive symptoms after adjustment for covariates and baseline severity (all p<0.01). Negative life-events interacted with cognitive vulnerability to depression to predict depressive symptoms. Locus of control (b1=0.16, SE=0.02, η2=0.01; b2=0.10, SE=0.02, η2=0.004, F=8.69, p<0.01) and explicit self-depressive associations (b1=0.10, SE=0.03, η2=0.02; b2=0.02, SE=0.04, F=7.50, p<0.01) were more strongly associated with the cognitive (b1) than the somatic (b2) symptom dimension of depression.

Limitations

The study sample is over-inclusive of depressed patients. Therefore it might be problematic generalizing the findings to the general population.

Conclusion

Cognitive etiological factors may play a role in a “cognitive” subtype of depression. The findings strengthen the notion that homogeneous measures of depressive symptoms enable a greater degree of discrimination between subtypes than a multidimensional conception of depression.  相似文献   
107.
目的 探讨慢性HBV感染孕妇所生新生儿脐带血与静脉血HBV标志物状况的一致性和相关性,以及与孕妇HBV感染标志物的相关性.方法 以HBsAg、HBeAg双阳性且HBV DNA>1 ×105拷贝/ml孕妇及新生儿为研究对象,孕妇分娩前采集静脉血,新生儿于注射乙肝免疫球蛋白、乙肝疫苗前采集静脉血.在清洁和去除脐带表面污染血液,并用酒精消毒后,用注射器采集脐带血.HBsAg、抗HBs、HBeAg、抗HBe采用雅培微粒子化学发光法(美国雅培公司试剂,Abbott Architac i2000)检测,HBV DNA含量经COBAS TagMan HBV DNA定量检测仪检测.结果 共入组孕妇383例及所生新生儿,静脉血和脐带血HBsAg的阳性检出率分别为61.2%和63.9%,HBeAg阳性检出率分别为83.2%和83.5%,HBV DNA阳性检出率分别为56.0%和59.4%,静脉血和脐带血之间均有一致性.静脉血和脐带血间HBsAg、HBeAg和HBV DNA含量的相关性具有统计学意义(r=0.766、0.857、0.692,P<0.000).新生儿静脉血和脐带血的HBeAg含量与孕妇的HBeAg含量具有相关性(r=0.362,P=0.000;r=0.352,P=0.000),而静脉血和脐带血的HBsAg含量与孕妇血清的HBsAg含量无相关性(r=0.023,P=0.785;r=0.04,P=0.604).结论 慢性HBV感染孕妇所生新生儿脐带血和静脉血HBV标志物状态有良好的一致性,可以以脐带血的HBV标志物反映新生儿静脉血HBV标志物.  相似文献   
108.
IntroductionVertical root fractures (VRFs) are among the most frequent causes of tooth loss, mainly of endodontically treated teeth. However, very few data is available about the occurrence of VRFs following apical surgery.MethodsPatient charts from 864 patients with 1058 teeth treated with apical surgery (September 1999 to December 2018) were retrospectively evaluated, if a VRF had occurred after surgery. The following, possibly influencing factors were analyzed: sex and age, type of treated tooth, primary versus resurgery, technique of root-end preparation, and timepoint of VRF diagnosis. Endpoints were either tooth extraction or the last follow-up.ResultsThe study cohort (55% women, 45% men) had a mean age of 52.00 ± 13.97 years (range 9–93 years). The overall rate of VRFs after apical surgery was 4% (42 of 1058 teeth). Among these 42 teeth, 33.3% were mandibular first molars and 26.2% were maxillary second premolars. The most frequently affected root was the mesial root of mandibular first molars (28.6%). With regard to the study parameters, significant differences of VRF rates were observed only for the type of tooth treated.ConclusionsA low VRF rate of 4% was observed in this study. VRFs commonly occurred in maxillary premolars and mandibular molars, with the mesial root of mandibular first molars affected most frequently. This is in line with previous reports about VRFs in endodontically treated teeth without additional apical surgery.  相似文献   
109.
《Journal of endodontics》2021,47(8):1198-1214
IntroductionThe purpose of this review was to determine the diagnostic accuracy of cone-beam computed tomographic (CBCT) imaging in detecting vertical root fractures (VRFs) in root-filled teeth compared with a reference standard (direct visualization).MethodsElectronic searches were performed in Medline, Scopus, Cochrane, and gray literature for English language articles until June 2020. Prospective and retrospective clinical studies using CBCT imaging to diagnose VRFs in root-filled teeth were included. Case reports and in vitro studies were excluded. The Quality Assessment of Diagnostic Accuracy Studies 2 tool was used to assess the risk of bias and applicability concerns. Meta-analysis was performed using Stata 16.1 software (StataCorp, College Station, TX) via the MIDAS v.3.0 package and METANDI module. Publication bias was evaluated using Deeks’ funnel plot analysis. Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) was performed to evaluate the certainty of evidence. This systematic review was registered in the Open Science Framework (10.17605/OSF.IO/7JKE2).ResultsEight articles were included in this systematic review and meta-analysis. Risk of bias assessment showed that 5 articles in the patient selection domain had low risk of bias with low applicability concern. In the index test and reference standard domains, 7 articles had moderate risk of bias with moderate applicability concern. Three articles had high RB in the flow and timing domain. There was no publication bias. CBCT imaging had a pooled sensitivity and specificity of 0.78 (95% confidence interval [CI], 0.64–0.88) and 0.80 (95% CI, 0.63–0.91), respectively, and an accuracy of 0.86 (95% CI, 0.83–0.89). CBCT imaging also had pooled positive and negative likelihood ratios of 4 and 0.2, respectively. In GRADE analysis, the quality of evidence was low for sensitivity and moderate for specificity when CBCT imaging was used for the diagnosis of VRF.ConclusionsThe overall quality assessment of the included articles showed that in the patient selection domain, the risk of bias was low, and it was moderate in the index test and reference standard domains. Evidence from this systematic review and meta-analysis indicates that CBCT imaging is still not a good tool for diagnosing VRFs in root-filled teeth compared with direct visualization.  相似文献   
110.
熊倩  吴珺华 《口腔医学》2021,41(7):608-613
目的 分析Ⅰ、Ⅱ、Ⅲ类颌骨关系患者面部软、硬组织标志点的差异,为咬合重建或无牙颌患者修复治疗提供参考。方法 收集2019年1月—2020年9月至同济大学附属口腔医院就诊拍摄头颅定位侧位片的患者,共计329例。根据ANB大小分为Ⅰ类(2°~5°)、Ⅱ类(>5°)和Ⅲ类患者(<2°);根据下颌平面角(FH MP)大小分为高角型(>32°)、均角型(22°~32°)和低角型(<22°)。对其进行面部软、硬组织高度、角度及比例的头影测量分析。结果 ①总人群中Ⅰ、Ⅱ、Ⅲ类患者共有22个测量值显示出统计学差异(P<0.05),其中前下面高(ANS Me)满足Ⅲ类患者>Ⅰ类患者>Ⅱ类患者。②在高角型、均角型和低角型中,Ⅰ、Ⅱ、Ⅲ类患者仍有11个测量值具有统计学差异(P<0.05)。③相关性分析显示ANS Me与其余测量值均具有相关性,其中患者关节点到髁顶点的距离(Ar Gn)与ANS Me的相关系数|r|Ⅰ=0.839,|r|Ⅱ=0.732,|r|Ⅲ=0.806,均具有高度相关性。结论 Ⅰ、Ⅱ、Ⅲ类颌骨关系患者的面部测量值具有差异性,修复治疗时应该把颌骨关系作为考量之一。  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