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   25404篇
  免费   1821篇
  国内免费   847篇
耳鼻咽喉   29篇
儿科学   578篇
妇产科学   181篇
基础医学   1700篇
口腔科学   40篇
临床医学   2712篇
内科学   7104篇
皮肤病学   48篇
神经病学   643篇
特种医学   2357篇
外国民族医学   13篇
外科学   3128篇
综合类   4210篇
预防医学   596篇
眼科学   81篇
药学   2273篇
  11篇
中国医学   1009篇
肿瘤学   1359篇
  2023年   417篇
  2022年   558篇
  2021年   829篇
  2020年   912篇
  2019年   866篇
  2018年   809篇
  2017年   909篇
  2016年   837篇
  2015年   928篇
  2014年   1572篇
  2013年   1754篇
  2012年   1373篇
  2011年   1507篇
  2010年   1209篇
  2009年   1359篇
  2008年   1245篇
  2007年   1382篇
  2006年   1219篇
  2005年   1028篇
  2004年   804篇
  2003年   785篇
  2002年   641篇
  2001年   577篇
  2000年   479篇
  1999年   369篇
  1998年   367篇
  1997年   329篇
  1996年   331篇
  1995年   314篇
  1994年   323篇
  1993年   232篇
  1992年   213篇
  1991年   213篇
  1990年   151篇
  1989年   148篇
  1988年   125篇
  1987年   104篇
  1986年   100篇
  1985年   128篇
  1984年   102篇
  1983年   54篇
  1982年   83篇
  1981年   67篇
  1980年   73篇
  1979年   55篇
  1978年   41篇
  1977年   44篇
  1976年   28篇
  1975年   18篇
  1974年   15篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
目的:分析无创呼吸机治疗慢性阻塞性肺疾病的临床疗效。方法:选取2019年3月~2020年12月天津市第四中心医院收治的84例慢性阻塞性肺疾病患者为研究对象,应用随机数字表法将其分为两组,组间一般资料差异无统计学意义(P>0.05)。患者入院后均给予祛痰以及解除气道痉挛等常规治疗,在此基础上对照组采用鼻导管持续低流量吸氧治疗,研究组采用无创呼吸机进行治疗。观察两组患者治疗前后肺通气功能指标和动脉血气指标,以及患者住院时间。结果:治疗前各项观察指标组间差异均无统计学意义(P>0.05)。治疗后研究组FEV1%和FEV1/FVC分别为(62.71±7.30)和(67.63±7.75)%,均显著优于对照组的(50.12±5.81)和(60.27±7.38)%(P<0.05)。治疗后研究组PaO2和PaCO2分别为(81.46±7.23)mmHg和(46.31±5.09)mmHg,均显著优于对照组的(67.70±6.44)mmHg和(58.28±6.62)mmHg(P<0.05)。同时研究组住院时间为(18.26±3.71)d,显著短于对照组的(22.65±3.84)d(P<0.05)。结论:无创呼吸机可以显著改善慢性阻塞性肺疾病患者病情。  相似文献   
2.
BackgroundSelection of the transcatheter heart valve size for a mitral valve-in-valve procedure is based on the type and manufacturer’s labelled size. However, accurate information of surgical heart valve (SHV) size may not be available in the patient’s medical record. The purpose of this study is to establish reference data for computed tomography (CT) dimensions of commonly used mitral SHV in order to determine the manufacturer’s labelled size from a cardiac CT data set.MethodsCT datasets of 105 patients with surgical mitral bioprosthesis and available manufacturer labeled datasets were included in the analysis. CT derived valve dimensions were assessed by two observers using multiplanar reformats aligned with the basal sewing ring. A circular region of interest was used in a standardized fashion to minimize influence of image acquisition and reconstruction parameters. Interobserver variability was assessed by Bland-Altman analysis.ResultsThe CT-derived dimensions were stratified by valve size and type, and SHV properties were demonstrated for 5 common valve types. Variability of measurements was small and inter-observer limits of agreement were narrow. Stratified by SHV type, no overlap was noted for CT-derived dimensions among different SHV sizes . A reference table of CT characteristics of surgical mitral bioprosthesis types was created.ConclusionThe study provides reference CT data for determining the manufacturers’ labeled SHV size across a range of commonly used mitral SHVs. The findings will be important to help identify types of surgical mitral bioprosthesis utilizing CT characteristics for patients without SHV size documentation.  相似文献   
3.
4.
PurposeTo create a nonsurgical animal model of osteoarthritis (OA) to evaluate the effects of embolotherapy during geniculate artery embolization (GAE).Materials and MethodsFluoroscopy-guided injections of 700 mg of sodium monoiodoacetate were performed into the left stifle in 6 rams. Kinematic data were collected before and after induction. At 10 weeks after induction, Subjects 1 and 4–6 underwent magnetic resonance (MR) imaging with dynamic contrast enhancement (DCE) and Subjects 1, 3, and 4–6 underwent angiography with angiographic scoring to identify regions with greatest disease severity for superselective embolization (75–250-μm microspheres). Target vessel size was measured. At 24 weeks after angiography, DCE-MR imaging, angiography, and euthanasia were performed, and bilateral stifles were harvested. Medial/lateral tibial and femoral condylar, patellar, and synovial samples were cut, preserved, decalcified, and scored using the Osteoarthritis Research Society International criteria. The stifle and synovium Whole-Organ Magnetic Resonance Imaging Score and Multicenter Osteoarthritis Study score were determined. The volume transfer constant (Ktrans) and extracellular volume fraction (ve) were calculated from DCE-MR imaging along the lateral synovial regions of interest.ResultsThe mean gross and microscopic pathological scores were elevated at 38 and 61, respectively. Mean synovitis score was elevated at 9.2. Mean pre-embolization and postembolization angiographic scores were 5 and 3.8, respectively. Mean superior, transverse, and inferior geniculate artery diameters were 3.1 mm ± 1.21, 2.0 mm ± 0.50, and 1.6 mm ± 0.41 mm, respectively. Mean pre-embolization and postembolization cartilage and synovitis scores were elevated at 35.13 and 73.3 and 5.5 and 9.2, respectively. The Ktrans/ve values of Subjects 4, 5, and 6 were elevated at 0.049/0.38, 0.074/0.53, and 0.065/0.51, respectively. Altered gait of the hind limb was observed in all subjects after induction, with reduced joint mobility. No skin necrosis or osteonecrosis was observed.ConclusionsA nonsurgical ovine animal knee OA model was created, which allowed the collection of angiographic, histopathological, MR imaging, and kinematic data to study the effects of GAE.  相似文献   
5.
6.
PurposeTo assess the safety and tolerability of a vandetanib-eluting radiopaque embolic (BTG-002814) for transarterial chemoembolization (TACE) in patients with resectable liver malignancies.Materials and MethodsThe VEROnA clinical trial was a first-in-human, phase 0, single-arm, window-of-opportunity study. Eligible patients were aged ≥18 years and had resectable hepatocellular carcinoma (HCC) (Child-Pugh A) or metastatic colorectal cancer (mCRC). Patients received 1 mL of BTG-002814 transarterially (containing 100 mg of vandetanib) 7–21 days prior to surgery. The primary objectives were to establish the safety and tolerability of BTG-002814 and determine the concentrations of vandetanib and the N-desmethyl vandetanib metabolite in the plasma and resected liver after treatment. Biomarker studies included circulating proangiogenic factors, perfusion computed tomography, and dynamic contrast-enhanced magnetic resonance imaging.ResultsEight patients were enrolled: 2 with HCC and 6 with mCRC. There was 1 grade 3 adverse event (AE) before surgery and 18 after surgery; 6 AEs were deemed to be related to BTG-002814. Surgical resection was not delayed. Vandetanib was present in the plasma of all patients 12 days after treatment, with a mean maximum concentration of 24.3 ng/mL (standard deviation ± 13.94 ng/mL), and in resected liver tissue up to 32 days after treatment (441–404,000 ng/g). The median percentage of tumor necrosis was 92.5% (range, 5%–100%). There were no significant changes in perfusion imaging parameters after TACE.ConclusionsBTG-002814 has an acceptable safety profile in patients before surgery. The presence of vandetanib in the tumor specimens up to 32 days after treatment suggests sustained anticancer activity, while the low vandetanib levels in the plasma suggest minimal release into the systemic circulation. Further evaluation of this TACE combination is warranted in dose-finding and efficacy studies.  相似文献   
7.
8.
9.
目的探讨主动脉瓣重度狭窄患者接受经导管主动脉瓣置换术(TAVR)治疗的有效性和安全性。方法回顾性选取2017年9月至2019年12月接受TAVR的主动脉瓣重度狭窄患者36例。收集患者的人口学、实验室检查、影像辅助检查等全部临床资料,对手术过程、成功率、并发症以及手术前后超声心动图结果等进行分析。结果患者平均年龄(72.42±6.14)岁,瓣膜置入成功率100%。与术前相比,术后第1天的脑钠肽、主动脉瓣最大跨瓣压差、主动脉瓣跨瓣流速差异均有统计学意义(均P<0.01),术后6个月随访左心室射血分数、左心室舒张末期内径及左心室收缩末期内径都有显著改善(均P<0.01)。并发症方面,住院期间1例(2.8%)患者因三度房室传导阻滞行永久性起搏器植入;术后1周有2例(5.6%)患者存在轻度瓣周漏(<2 mm),术后6个月随访时只有1例(2.8%)患者存在轻度瓣周漏;术后6个月随访时1例(2.8%)患者缺血性卒中。结论主动脉瓣重度狭窄患者行TAVR治疗有较好的安全性和有效性,可有效改善左心室重塑。  相似文献   
10.
Introduction and objectivesSpontaneous portosystemic shunts (SPSS) are a common cause of recurrent hepatic encephalopathy (HE). Shunt occlusion is an effective and safe procedure when performed in patients with cirrhosis and preserved liver function. We aimed to describe our experience with SPSS embolization after liver transplantation (LT).PatientsWe identified five patients who underwent SPSS embolization after LT. Clinical, biochemical and technical procedure data were collected.ResultsAt presentation, all patients had developed graft cirrhosis and HE after LT. Median Model for End-stage Liver Disease (MELD) at embolization was 9 (range 7-12), median Child-Pugh was 8 (range 7-9). Splenorenal and mesocaval shunt were the most frequent types of SPSS found. Three patients have been completely free of HE. Of the two patients who had HE recurrence after embolization, one patient had two episodes of HE which was controlled well with medications. The other patient required three embolizations because of recurrent HE. Median follow-up was 4.4 years (range 1.0-5.0) and MELD score at last follow up was 13 (range 10-18) and median Child-Pugh score B, 7 points (range 5-12).ConclusionsSPSS can be considered as a cause of HE after LT. SPSS embolization is feasible and safe in LT recipients.  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