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   4623篇
  免费   449篇
  国内免费   126篇
耳鼻咽喉   54篇
儿科学   62篇
妇产科学   92篇
基础医学   526篇
口腔科学   131篇
临床医学   529篇
内科学   747篇
皮肤病学   52篇
神经病学   174篇
特种医学   229篇
外科学   495篇
综合类   608篇
预防医学   333篇
眼科学   141篇
药学   613篇
  2篇
中国医学   229篇
肿瘤学   181篇
  2024年   9篇
  2023年   100篇
  2022年   140篇
  2021年   316篇
  2020年   241篇
  2019年   199篇
  2018年   206篇
  2017年   214篇
  2016年   173篇
  2015年   188篇
  2014年   343篇
  2013年   316篇
  2012年   240篇
  2011年   254篇
  2010年   199篇
  2009年   191篇
  2008年   196篇
  2007年   199篇
  2006年   186篇
  2005年   138篇
  2004年   92篇
  2003年   100篇
  2002年   98篇
  2001年   63篇
  2000年   72篇
  1999年   70篇
  1998年   63篇
  1997年   50篇
  1996年   53篇
  1995年   50篇
  1994年   49篇
  1993年   38篇
  1992年   39篇
  1991年   23篇
  1990年   25篇
  1989年   26篇
  1988年   26篇
  1987年   25篇
  1986年   28篇
  1985年   27篇
  1984年   22篇
  1983年   8篇
  1982年   19篇
  1981年   24篇
  1980年   11篇
  1979年   17篇
  1978年   7篇
  1976年   5篇
  1975年   4篇
  1974年   6篇
排序方式: 共有5198条查询结果,搜索用时 31 毫秒
1.
目的:探讨2型糖尿病(T2DM)患者不同脂质参数与糖尿病肾病(DKD)发生的相关性。方法:检测226例T2DM患者血清TC、TG、LDL-C、HDL-C水平及相关生化指标,计算血浆致动脉硬化指数(AIP)以及脂质三角相关指标(TC/HDL-C、TG/HDL-C、LDL-C/HDL-C)。根据DKD临床诊断标准和Mogensen分期标准分为:Ⅰ~Ⅱ期组136例,Ⅲ期组55例,Ⅳ~Ⅴ期组35例。应用多因素logistic回归分析不同脂质参数与DKD发生的关系。结果:与Ⅰ~Ⅱ期组相比,随着DKD分期加重,TC、TG、LDL-C、LDL-C/HDL-C、AIP水平明显增高(P<0.01)。LDL-C/HDL-C和AIP与24 h尿蛋白水平呈正相关(r=0.724;r=0.769,均P<0.05)。LDL-C/HDL-C和AIP是T2DM合并DKD患者的独立预测因子(P=0.002;P=0.004)。结论:LDL-C/HDL-C和AIP对T2DM合并DKD病情进展有较高的预测价值,可为临床诊治提供参考。  相似文献   
2.
BACKGROUND Degree of portal hypertension(PH) is the most important prognostic factor for the decompensation of liver cirrhosis and death, therefore adequate care for patients with liver cirrhosis requires timely detection and evaluation of the presence of clinically significant PH(CSPH) and severe PH(SPH). As the most accurate method for the assessment of PH is an invasive direct measurement of hepatic venous pressure gradient(HVPG), the search for non-invasive methods to diagnose these conditions is actively ongoing.AIM To evaluate the feasibility of parameters of endogenously induced displacements and strain of liver to assess degree of PH.METHODS Of 36 patients with liver cirrhosis and measured HVPG were included in the casecontrol study. Endogenous motion of the liver was characterized by derived parameters of region average tissue displacement signal(dantero, dretro, d RMS) and results of endogenous tissue strain imaging using specific radiofrequency signal processing algorithm. Average endogenous strain μ and standard deviation σ of strain were assessed in the regions of interest(ROI)(1 cm × 1 cm and 2 cm × 2 cm in size) and different frequency subbands of endogenous motion(0-10 Hz and 10-20 Hz).RESULTS Four parameters showed statistically significant(P 0.05) correlation with HVPG measurement. The strongest correlation was obtained for the standard deviation of strain(estimated at 0-10 Hz and 2 cm × 2 cm ROI size). Three parameters showed statistically significant differences between patient groups with CSPH, but only dretro showed significant results in SPH analysis. According to ROC analysis area under the curve(AUC) of the σROI[0…10 Hz, 2 cm × 2 cm] parameter reached 0.71(P = 0.036) for the diagnosis of CSPH; with a cut-off value of 1.28 μm/cm providing 73% sensitivity and 70% specificity. AUC for the diagnosis of CSPH for μROI[0…10 Hz, 1 cm × 1 cm] was 0.78(P = 0.0024); with a cut-off value of 3.92 μm/cm providing 73% sensitivity and 80% specificity. Dretro parameter had an AUC of 0.86(P = 0.0001) for the diagnosis of CSPH and 0.84(P = 0.0001) for the diagnosis of SPH. A cut-off value of-132.34 μm yielded 100% sensitivity for both conditions, whereas specificity was 80% and 72% for CSPH and SPH respectively.CONCLUSION The parameters of endogenously induced displacements and strain of the liver correlated with HVPG and might be used for non-invasive diagnosis of PH.  相似文献   
3.
4.
108例支气管哮喘患者舌脉象特征分析   总被引:1,自引:0,他引:1  
目的:探讨对支气管哮喘临床辨证有意义的舌脉象客观指标,以辅助临床诊断。方法:应用TP—I型中医舌脉象数字化分析仪检测108例患者舌脉象参数,分析支气管哮喘发作期与缓解期的舌脉象特征。结果:108例支气管哮喘患者的舌象中,舌色以淡红舌、淡紫舌多见,舌苔以白苔、黄苔、薄苔为多见;脉象以弦脉、滑脉、弦滑脉为多见;舌脉象参数中舌色指数、苔色指数、厚苔指数、胖瘦指数在哮喘发作期各证型中有显著性差异(P〈0.05);RPSR1、RPSR3、RPSR4、RBF、RLMS2、PLMP2、RLMS3、RLMP3在哮喘发作期与缓解期有显著性差异(P〈0.05)。结论:支气管哮喘患者的脉象参数、舌色指数、苔色指数、厚苔指数、胖瘦指数、RPSR1、RPSR3、RPSR4、RBF、RLMS2、PLMP2、RLMS3、RLMP3对其辨证分型有重要参考价值。  相似文献   
5.
Abstract Bleeding on probing (BOP) and the gingival index have been used to clinically characterize the degree of gingival inflammation. It is, however, unclear to what extent these parameters correlate to each other and to probing pocket depth (PD). The purpose of this clinical study was to evaluate the association between BOP and GI bleeding (scores of 2 and 3), as well as the relationship of these variables to PD, in a group of patients presenting with naturally-occurring gingivitis. Based on screening examinations of 125 subjects with at least 20 teeth, no more than 4 sites with PD over 6 mm, a BOP frequency of 30% or greater, and no systemic condition that would influence the inflammatory response, were selected. 2 weeks after screening they were examined at 6 sites per tooth for plaque index, GI, PD and BOP. A standardized pressure sensitive probe (Florida Probe) with 20 g probing force was used for BOP and PD measurements. In this population, means of 40.9% (S.E.= 1.36) BOP sites and 35.3% (S.E, = 1.81) GI bleeding sites per patient were found. A total of 20,008 sites ranging in PD up to 5.9 mm were evaluated; however, the majority of sites (19,723, 98.6%) presented with <4 mm PD. When sites were evaluated, BOP demonstrated a positive correlation with PD, whereas GI bleeding correlated with PH. For sites characterized by the absence of BOP as well as the absence of GI bleeding (scores 0 and 1), the highest % of agreement between the 2 indices (77.7%) was found in shallow sites (0.1–2 mm). In contrast, when sites presenting with both BOP and GI bleeding were analyzed, the highest % of agreement (85,4%) was found for sites with PD >4.0 mm. In this gingivitis population group, it appears that BOP and GI bleeding evaluate distinct inflammatory1 conditions of the gingival tissues, and the relationship between the 2 clinical parameters may vary according to PD at the individual site examined.  相似文献   
6.
彩色多普勒在心脏起搏器综合征诊断中的应用价值   总被引:1,自引:1,他引:0  
目的 :探讨运用彩色多普勒血流显像 (CDFI)并结合心电图 (ECG)诊断起搏器综合征 (PMS)的临床价值。方法 :对具有详实临床及ECG资料的心室按需 (VVI)起搏器安置患者 6 0例及对照组 4 8例进行CDEI检查 ,观察起搏组与对照组的三尖瓣返流 (TR)的发生率、返流程度 ,并分析二者之间的相关性。结果 :起搏组出现逆传P波 (即PMS阳性 )者 15例 ,CDFI检测出现TR者 2 0例 ,明显高于对照组 ,且PMS阳性者TR发生率明显高于PMS阴性者 ,表明安置VVI起搏器后出现逆传P波与TR的发生相关性良好。结论 :CDFI对PMS的诊断具有重要意义 ,尤其将ECG与CDFI结合应用有助于诊断率的提高。  相似文献   
7.
大肠癌中mdm2表达与临床相关性的研究   总被引:3,自引:1,他引:2  
目的:探讨mdm2在大肠癌中表达与临床相关性的关系。方法:采用免疫组织化学方法研究93例大肠癌组织中MDM2蛋白表达水平及其与P21蛋白表达的临床相关性。结果:我们观察到MDM2表达在临床分期中有显著差异(P〈0.05)。MDM2蛋白表达与远处转移显著相关(X^2=15.977,P=-0.000)。MDM2表达与P21表达成正相关(P=0.023。r=0.210)。单因素的统计学分析结果表明临床分期、远处转移、MDM2蛋白表达、P21蛋白表达、治疗等单项均可以作为影响患者生存时间的危险因子。多因素Cox回归生存分析结果表明临床分期、远处转移、MDM2蛋白表达、治疗4项对结直肠癌患者的生存时间有影响。结论:mdm2基因的表达与癌症的恶性演进呈正相关;mdm2基因的表达与P21表达成正相关。  相似文献   
8.
目的 通过对仿真与真实表面肌电信号(sEMG)的波形匹配以及肌疲劳现象的分析,研究sEMG信号的模型参数辨识问题. 方法 在运动单位仿真的基础上,引入神经激励对运动单位的募集和发放控制特性,建立了一个较为完善的sEMG信号生理学模型.利用调整模型相关生理参数使仿真与真实sEMG信号的运动单位动作电位(MUAP)波形相匹配的方法,实现对模型参数进行估计,通过调节肌纤维传导速度(MFCV)使仿真与真实sEMG信号的平均频率(MNF)及中值频率(MDF)拟合直线趋势相似的方法,研究肌肉的疲劳现象及其机理. 结果 适当调节sEMG信号模型参数可使仿真信号波形逼近真实sEMG信号波形,各个肌纤维的MFCV在模拟恒力持续收缩过程中减小时,仿真信号的MNF和MDF拟合直线呈下降趋势. 结论 采用模型方法能够实现仿真与真实sEMG信号波形的良好匹配,并能够有效地表达肌肉的疲劳过程,可应用于肌电信号相关领域的研究.  相似文献   
9.
超声引导心脏靶点起搏和精确消融的初步实验研究   总被引:2,自引:1,他引:1  
目的 初步建立超声引导监控下的心脏传导系统的靶点起搏和精确消融方法。方法 12只杂种犬急性开胸模型,经颈静脉插入超声导管分别进入上腔静脉,右心房,室或经心脏表面进行心脏扫描,获取并确认心脏传导系统超声解剖结构标志及其心肌激动顺序,确定靶组织空间益关系,引导经股静脉插入的心脏起搏或消融导管和经心脏表面插入的穿刺针到达靶组织并确认心内膜面接触,进行靶点起搏,精确射频及化学消融,超声实时监控全过程,对心脏离体标本进行病检和切片,确认靶点起搏位置,观察消融和起搏对心脏传导系统和组织细胞的损害。结果 超声能够在观察到心脏传导系统重要靶点部位,解剖结构的同时评价其结构内心肌激动的起始和传导顺序,能引导介入导管准确到达靶点组织,监控电极与心内膜央的接触,监控穿刺针在靶点组织内的准确空间位置,避免损伤冠状动脉及传导组织,及时评价起搏和消融损伤效果。确定终止治疗时机并监控并发症的发生,病解和切片表明超声引导心脏射频和化学消融定位准确,效果肯定。结论 超声能够引导心脏介入导管和穿刺针进行心脏靶点起搏和精确消融,定点消融心肌,使起搏和消融治疗更为精确,该方法将为临床心脏电生理疾病的治疗提供一种全新的简便,准确技术方法和手段。  相似文献   
10.
The data concerning the value of duplex sonography in diagnosingparenchymatous renal allograft dysfunction are controversial.Most early studies did not take into consideration the manyfactors influencing resistance parameters. We therefore performeda prospective, biopsy-controlled study with exclusion of allknown sources of error regarding resistance parameters. Furthermorewe investigated the value of a new resistance parameter, thesystolic deceleration percentage. Forty-seven duplex sonographicstudies were performed on 43 patients (30 male, 13 female, medianage 47 years, range 7–70). Fourteen studies were doneon normally functioning grafts (control group) an average of33 days after transplantation. Thirty-three studies were performedon dysfunctional grafts immediately prior to biopsy. Graftswhich had been transplanted more than a year previously or withvascular findings or any other clinical or sonographic pathologyprobably explaining function deterioration were excluded. Inall patients, the resistive index (RI), pulsatility index (PI)and systolic deceleration percentage (DP) were calculated inthe main renal artery and in the interlobar artery. Of the 33grafts with dysfunction, nine had vascular rejection (VR), 11interstitial rejection (IR), 11 cyclosporin A toxicity (CAT)and two other histologies (OR). The mean RI in normal grafts(NO) was 0.71±0.06 in the main artery and 0.68±0.06in the interlobar artery, in VR 0.86±0.12 and 0.80±0.18,in IR 0.72±0.05 and 0.70±0.07, in CAT 0.67±0.06and 0.65±0.07 and in OR 0.64±0.07 and 0.60±0.01.For PI, the values were 1.45±0.23 and 1.41±0.28(NO), 3.5±2.13 and 2.92±2.16 (VR), 1.55±0.26and 1.46±0.33 (IR), 1.32±0.25 and 1.27±0.26(CAT) and 1.30±0.34 and 1.13±0.04 (OR). For DPwe calculated 28±5% and 29±6% (NO), 43±14%and 36±6% (VR), 29±9% and 27±9% (IR), 31±8%and 32±7% (CAT ) and 32±4% and 28±3% (OR).The sensitivity/specificity for VR with a cutoff mean+2 SD was0.44/1 for RI, 0.55/0.97 for PI and 0.33/0.89 for DP. It wasconcluded that:(1) despite the high selection of our patientgroup, diagnostic accuracy of duplex sonography for diagnosingparenchymatous function disorder in renal allograft remainsinsufficient; (2) in vascular rejection only, the resistanceparameters differ significantly from the values of normal allografts;(3) the higher the cutoff of resistance parameters, the betterthe specificity and the worse the sensitivity for diagnosingvascular rejection; (4) of all investigated resistance parameters,the RI is the most practical due to a simple measurement technique.  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