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   16552篇
  免费   1144篇
  国内免费   565篇
耳鼻咽喉   59篇
儿科学   276篇
妇产科学   130篇
基础医学   1147篇
口腔科学   84篇
临床医学   2581篇
内科学   3321篇
皮肤病学   58篇
神经病学   441篇
特种医学   1278篇
外国民族医学   4篇
外科学   3064篇
综合类   2584篇
现状与发展   1篇
预防医学   366篇
眼科学   1033篇
药学   1015篇
  9篇
中国医学   377篇
肿瘤学   433篇
  2024年   16篇
  2023年   278篇
  2022年   362篇
  2021年   587篇
  2020年   604篇
  2019年   534篇
  2018年   493篇
  2017年   544篇
  2016年   533篇
  2015年   565篇
  2014年   1015篇
  2013年   1071篇
  2012年   988篇
  2011年   1062篇
  2010年   904篇
  2009年   879篇
  2008年   927篇
  2007年   921篇
  2006年   855篇
  2005年   752篇
  2004年   630篇
  2003年   514篇
  2002年   436篇
  2001年   350篇
  2000年   287篇
  1999年   240篇
  1998年   235篇
  1997年   239篇
  1996年   140篇
  1995年   163篇
  1994年   158篇
  1993年   117篇
  1992年   113篇
  1991年   97篇
  1990年   66篇
  1989年   61篇
  1988年   72篇
  1987年   53篇
  1986年   58篇
  1985年   57篇
  1984年   42篇
  1983年   27篇
  1982年   42篇
  1981年   42篇
  1980年   30篇
  1979年   32篇
  1978年   21篇
  1977年   17篇
  1976年   12篇
  1975年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
PurposeTo evaluate the effectiveness and safety of fluoroscopy-guided percutaneous high ligation (FPHL) combined with fluoroscopy-guided foam sclerotherapy (FGFS) to treat varicose veins of the great saphenous veins (GSVs).Materials and MethodsThis was a retrospective study of 113 patients (mean age, 62.1 ± 10.8 years; 60 men) with varicose veins of the GSVs (133 limbs) that were treated with FPHL combined with FGFS between April 1 and October 31, 2019. Demographic and clinical data were collected from these patients before the FPHL procedure, after which FGFS was performed. The preterminal GSV was ligated percutaneously by a percutaneously-positioned polypropylene ligature under fluoroscopic guidance. The outcome of ligation was confirmed by venography. Then, foam sclerotherapy was performed under fluoroscopy. At 1-year follow-up, GSV occlusion was evaluated by ultrasound. The venous clinical severity scores (VCSSs) were compared between the preoperative and 1-year follow-up periods.ResultsThe technical success rate was 100% (133 limbs). Complete 12-month follow-up was available for 112 limbs (84.2%) and 103 of these limbs (92.0%) remained occluded during this period. The VCSS improved from 4.71 ± 2.15 to 0.74 ± 0.60 (V = 6328, P < .001). During follow-up, there were 16 limbs with thrombophlebitis and 38 limbs with saphenous junction pain; these events were alleviated within 2 weeks of the procedure. There was no deep venous thrombosis or other severe adverse events.ConclusionsFPHL combined with FGFS to treat varicose veins in the GSVs achieved an occlusion rate of 92% and improved the clinical symptoms within 1 year; this minimally-invasive procedure was safe and effective.  相似文献   
3.
4.
PurposeTo evaluate temporal trends, practice variation, and associated outcomes with the use of intravascular ultrasound (US) during deep venous stent placement among Medicare beneficiaries.Materials and MethodsAll lower extremity deep venous stent placement procedures performed between January 1, 2017, and December 31, 2019 among Medicare beneficiaries were included. Temporal trends in intravascular US use were stratified by procedural setting and physician specialty. The primary outcome was a composite of 12-month all-cause mortality, all-cause hospitalization, or repeat target vessel intervention. The secondary outcome was a composite of 12-month stent thrombosis, embolization, or restenosis.ResultsAmong the 20,984 deep venous interventions performed during the study period, 15,184 (72.4%) utilized intravascular US. Moderate growth in intravascular US use was observed during the study period in all clinical settings. There was a variation in the use of intravascular US among all operators (median, 77.3% of cases; interquartile range, 20.0%–99.2%). In weighted analyses, intravascular US use during deep venous stent placement was associated with a lower risk of both the primary (adjusted hazard ratio, 0.72; 95% confidence interval [CI], 0.69–0.76; P < .001) and secondary (adjusted hazard ratio, 0.32; 95% CI, 0.27–0.39; P < .001) composite end points.ConclusionsIntravascular US is frequently used during deep venous stent placement among Medicare beneficiaries, with further increase in use from 2017 to 2019. The utilization of intravascular US as part of a procedural strategy was associated with a lower cumulative incidence of adverse outcomes after the procedure, including venous stent thrombosis and embolization.  相似文献   
5.
PurposeTo assess the critical role of transjugular intrahepatic portosystemic shunt (TIPS) in the management of Budd-Chiari syndrome (BCS), as the data with respect to the safety and outcome of TIPS in patients with BCS are scarce because of the rarity of the disease.Materials and MethodsA comprehensive search of literature of various databases from 2000 to October 2021 was conducted for studies evaluating the outcome of TIPS in patients with BCS. The primary outcomes of the analysis were technical and clinical success, adverse events and mortality associated with TIPS, dysfunction of TIPS, need for TIPS revision, need for liver transplantation (LT), and 1-year survival.ResultsA total of 33 studies (1,395 patients) were included in this meta-analysis. The pooled rates and 95% confidence intervals of various outcomes were 98.6% (97.6–99.7) for technical success, 90.3% (86.0–94.6) for clinical success, 10.0% (6.5–13.6) for major adverse events, 0.5% (0.2–1.0) for TIPS-related mortality, 11.6% (7.8–15.4) for post-TIPS hepatic encephalopathy (HE), 40.1% (32.5–47.7) for TIPS dysfunction, 8.6% (4.9–12.4) for the need for TIPS revision, 4.5% (2.8–6.2) for the need for LT, and 94.6% (93.1–96.1) for 1-year survival. Publication bias was seen with all outcomes except for post-TIPS HE, TIPS dysfunction, and the need for LT.ConclusionsThe existing literature supports the feasibility, safety, and efficacy of TIPS in the treatment of BCS. Deciding the optimal timing of TIPS in BCS needs further studies.  相似文献   
6.
目的 分析超声及应变式弹性成像预测超声引导下置入腘静脉血管鞘治疗下肢深静脉血栓形成(DVT)成功与否的价值。方法 回顾性分析103例接受超声引导下置入患侧腘静脉血管鞘的DVT患者的术前超声资料,比较置入血管鞘失败与成功病例腘静脉超声及应变式弹性成像表现差异;绘制差异有统计学意义超声参数的受试者工作特征曲线,获得其预测血管鞘置入失败的阈值,对每个参数阈值赋值1分,得到联合超声评分,以实际置入结果为标准,评价超声单一参数及联合评分的预测效能。结果 103例中,对100例行单侧、3例行双侧腘静脉置入血管鞘,包括左侧腘静脉71支、右侧35支,共106支腘静脉;对其中95支腘静脉置入血管鞘成功(成功组),11支失败(失败组)。相比成功组,失败组腘静脉内径及腘静脉与腘动脉内径比值均较小,血栓为等或高回声,与血管壁边界模糊,腘静脉应变式弹性评分为硬。以超声单一参数及联合评分预测置入血管鞘成功与否的曲线下面积分别为0.909、0.926、0.865、0.899、0.958及0.940(P均<0.001)。结论 患侧腘静脉超声及应变式弹性成像能有效预测对下肢DVT患者行超声引导下置入腘静脉血管鞘成功与否。  相似文献   
7.
Recently, we reported that titanium dioxide (TiO2) materials activated endothelial cells via Kruppel-like factor (KLF)-mediated nitric oxide (NO) dysfunction, but the roles of physical properties of materials are not clear. In this study, we prepared nanobelts from P25 particles and compared their adverse effects to human umbilical vein endothelial cells (HUVECs). TiO2 nanobelts had belt-like morphology but comparable surface areas as P25 particles. When applied to HUVECs, P25 particles or nanobelts did not induce cytotoxicity, although nanobelts were much more effective to increase intracellular Ti element concentrations compared the same amounts of P25 particles. Only nanobelts significantly induced THP-1 adhesion onto HUVECs. Consistently, nanobelts were more significant to induce the expression of intracellular adhesion molecule-1 (ICAM1) and the release of soluble ICAM-1 (sICAM-1), indicating that nanobelts were more potent to induce endothelial activation in vitro. As the mechanisms for endothelial activation, both P25 and nanobelts reduced the generation of intracellular NO as well as the expression of NO regulators KLF2 and KLF4. Combined, the results from this study indicated that the different morphologies of P25 particles and nanobelts only changed their internalization into HUVECs but showed minimal impact on KLF-mediated NO signaling pathways.  相似文献   
8.
9.
ObjectiveThe objective of this study was to investigate the association between morphological variation and postsurgical pulmonary vein (PV) stenosis (PPVS) in patients with cardiac total anomalous pulmonary venous connection (TAPVC).MethodsThis single-center, retrospective study included 168 pediatric patients who underwent surgical repair of cardiac TAPVC from 2013 to 2019 (connection to the coronary sinus [CS], n = 136; connection directly to the right atrium [RA], n = 32). Three-dimensional computed tomography modeling and geometric analysis were performed to investigate the morphological features; their relevance to the PPVS was examined.ResultsThe connection type had no association with PPVS (CS type: 18% vs right atrial type: 19%; P = .89) but there was a higher incidence of PPVS in patients with a single PV orifice than > 1 orifice (P < .001). Confluence-to-total PV area ratio (hazard ratio, 4.78, 95% CI, 1.86-12.32; P = .001) and length of drainage route (hazard ratio, 1.22; 95% CI, 1.14-1.31; P < .001) had a 4- and 1-fold increase in the risk for PPVS in the CS type after adjustment for age and preoperative pulmonary venous obstruction. In the right atrial type, those with anomalous PV return to the RA roof were more likely to develop PPVS than to the posterior wall of the RA (P < .001).ConclusionsThe number of inter-junction PV orifice correlated with PPVS development in cardiac TAPVC. The confluence-to-total PV ratio, length of drainage route, and anomalous PV return to the RA roof are important predictors for PPVS. Morphological subcategorization in this clinical setting can potentially assist in surgical decision-making.  相似文献   
10.
An ovine iliac vein thrombosis model was devised to test a wall-contacting rotational thrombectomy device. Thrombosis was successfully induced in 9 sheep with an average clot length of 31 mm ± 12 and >60% vessel occlusion on angiography. The thrombus was subsequently removed, maintaining normal intraoperative pulmonary arterial pressure (5.9 mm Hg ± 3.6) and complete distal reperfusion after thrombectomy. Additionally, the sheep were without signs of vascular trauma or embolic complications on gross necropsy and histopathologic analysis. The findings from this study support the use of an ovine iliac deep vein thrombosis model for testing of a lower extremity thrombectomy device.  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