全文获取类型
收费全文 | 58323篇 |
免费 | 6079篇 |
国内免费 | 1264篇 |
专业分类
耳鼻咽喉 | 240篇 |
儿科学 | 832篇 |
妇产科学 | 653篇 |
基础医学 | 6267篇 |
口腔科学 | 1001篇 |
临床医学 | 5845篇 |
内科学 | 4265篇 |
皮肤病学 | 336篇 |
神经病学 | 1459篇 |
特种医学 | 3100篇 |
外国民族医学 | 75篇 |
外科学 | 7202篇 |
综合类 | 7039篇 |
现状与发展 | 6篇 |
一般理论 | 1篇 |
预防医学 | 2344篇 |
眼科学 | 513篇 |
药学 | 3903篇 |
52篇 | |
中国医学 | 1162篇 |
肿瘤学 | 19371篇 |
出版年
2024年 | 692篇 |
2023年 | 1140篇 |
2022年 | 1981篇 |
2021年 | 2908篇 |
2020年 | 2755篇 |
2019年 | 2484篇 |
2018年 | 2287篇 |
2017年 | 2203篇 |
2016年 | 2245篇 |
2015年 | 2637篇 |
2014年 | 3584篇 |
2013年 | 3903篇 |
2012年 | 2905篇 |
2011年 | 3244篇 |
2010年 | 2458篇 |
2009年 | 2456篇 |
2008年 | 2458篇 |
2007年 | 2595篇 |
2006年 | 2469篇 |
2005年 | 2207篇 |
2004年 | 1873篇 |
2003年 | 1735篇 |
2002年 | 1473篇 |
2001年 | 1301篇 |
2000年 | 1071篇 |
1999年 | 944篇 |
1998年 | 833篇 |
1997年 | 780篇 |
1996年 | 637篇 |
1995年 | 599篇 |
1994年 | 477篇 |
1993年 | 449篇 |
1992年 | 404篇 |
1991年 | 367篇 |
1990年 | 321篇 |
1989年 | 288篇 |
1988年 | 280篇 |
1987年 | 217篇 |
1986年 | 234篇 |
1985年 | 273篇 |
1984年 | 246篇 |
1983年 | 184篇 |
1982年 | 234篇 |
1981年 | 184篇 |
1980年 | 117篇 |
1979年 | 113篇 |
1978年 | 102篇 |
1977年 | 76篇 |
1976年 | 69篇 |
1975年 | 37篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Peet J. van der Vyver Farzana Paleker Martin Vorster Francois A. de Wet 《Journal of endodontics》2019,45(1):62-67
Introduction
The aim of this study was to evaluate the root canal shaping effect of instruments manufactured from nickel titanium, M-Wire, and Gold wire with different glide path preparation techniques.Methods
One hundred thirty-five mesiobuccal canals of extracted human maxillary molars were randomly divided into 3 equal groups (N = 45) for glide path preparation with K-files (KF) (Dentsply Sirona, Ballaigues, Switzerland), One G (OG) files (Micro-Mega, Besançon, France), and ProGlider (PG) files (Dentsply Sirona). Specimens of each glide path group were further divided equally into 3 groups for instrumentation with ProTaper Next (PTN, Dentsply Sirona), One Shape (OS, Micro-Mega), and WaveOne Gold (WOG, Dentsply Sirona) systems (n = 15). Micro–computed tomographic imaging was used to scan teeth before instrumentation and after shaping to compare centering ratio and canal transportation values at the apical, midroot, and coronal levels and the overall changes in canal volume. Data sets were statistically analyzed (analysis of variance and Kruskal-Wallis H tests).Results
The centering ratios for all groups were statistically similar at all levels. Apical canal transportation was significantly high for K/OS and K/PTN (P = .003). Midroot canal transportation was significantly high for K/PTN, K/OS, and OG/OS (P = .0003). Coronal canal transportation was significantly high for K/PTN and K/OS (P = .011). The highest change in canal volume was observed with all PTN groups and the lowest with PG/WOG (P = .06).Conclusions
WOG manufactured from Gold wire combined with PG showed better root canal shaping ability and removed less dentin from the canal walls. The nickel-titanium (OS) and M-Wire (PTN) instruments used in combination with KF significantly transported more canals. PTN removed the most dentin from the canal walls regardless of the GPP technique. 相似文献2.
Abdol-Mohammad Kajbafzadeh Reza Khorramirouz Seyedeh Maryam Kameli Kiarad Fendereski Seyedeh Sima Daryabari Seyed Mohammad Tavangar Bahram Azizi Garajegayeh 《The Journal of thoracic and cardiovascular surgery》2019,157(4):1494-1502
Background
Various investigations have reported that the internal mammary artery (IMA) is an efficient and functional choice of conduit for vascular graft surgeries, especially for coronary artery bypass grafts; however, the quest to find an ideal vascular substitute remains. We hypothesized that acellular IMA could be an appropriate graft for small-diameter vascular bypasses that could be used in various surgeries including coronary artery bypass grafting.Methods
We decellularized human IMAs and performed histologic evaluations and scanning electron microscopy to confirm the decellularization process and the preservation of the extracellular matrix. Subsequently, we grafted the scaffolds into the superficial femoral arteries of 8 New Zealand rabbits with an end-to-end anastomosis. Computed tomography angiograms were provided at 3, 12, and 36 months postoperatively. Subsequently, the animals were killed, and biopsies were taken for histologic and immunohistochemical assessments.Results
Evaluation of the acellular tissue confirmed the efficacy of the decellularization protocol and the preservation of the extracellular matrix. All 8 animals survived the entire follow-up period. Doppler ultrasonography and computed tomography angiographies verified the conduit's patency. Histologic assessments depicted the recellularization of all 3 layers of the scaffold. Smooth muscle cells were detected in tunica media. Immunohistochemical assessments confirmed these findings.Conclusions
In conclusion, we demonstrated that acellular human IMA could be used as an efficient small-diameter vascular substitute with high patency. These findings could pave the path for future investigations on the clinical application of acellular IMA as a novel vascular graft for small-diameter bypass surgeries. 相似文献3.
《Injury》2023,54(2):318-328
PurposeThis study intended to determine the properties of induced membranes after various periods of polymethyl methacrylate (PMMA) retention and the effect of different retention intervals on subsequent defect repair.MethodsModel of a critical bone defect in rabbits was prepared to obtain the induced membrane. For varying intervals of spacer insertion (2, 4, 6, 8, 12, 16, and 20 weeks postoperatively), angiogenesis, osteogenesis, and MSC-related properties were analyzed by immunohistochemistry and western-blot. Furthermore, 2, 4, 6, and 8 weeks after PMMA insertion, bone grafting was performed. Characteristics of defect repair were analyzed by X-ray and micro-CT analysis.ResultsThe induced membrane displayed angiogenesis, osteogenesis, and MSC-related properties from the 2- to 20-week intervals. Quantitation of protein expression (RUNX2, ALP, VEGF, TGF-beta, OCT4, and STRO1) revealed that selected proteins gradually rose to a high level at 4–8 weeks postoperatively and then decreased to a low level over a long time period. Following bone grafting, the most new bone formation was in the group when grafting was performed at 4 weeks, followed by the groups at 2 and 6 weeks, with the least in the group at 8 weeks.ConclusionThe induced membrane displays angiogenesis, osteogenesis, and MSC-related properties from the 2- to 20-week intervals. These were increased to a peak level at 4–8 weeks postoperatively and then gradually decreased. The optimal timing for bone grafting at the second stage in the presented model was 4 weeks after PMMA insertion. 相似文献
4.
The purpose of this study was to design a toolkit that interacts with the Monaco (Elekta AB, Stockholm, Sweden) treatment planning system (TPS) for optimization of intensity-modulated radiation therapy and volumetric-modulated arc therapy without the need for a dedicated application programming interface. Successful inverse planning of radiotherapeutic treatment depends on the tweaking of many parameters; a tool was thus needed to explore these parameters more exhaustively without significantly increasing planning time. The software that we used was based on an open-source library that mimics human interaction with Microsoft Windows applications. We developed a simple Autoflow software routine that analyzes and optimizes calculated plans by considering the relative impact of different cost functions and modifying constraints accordingly. It was also designed to change segmentation parameters to fit more complex treatments. The toolkit is publicly available for download at https://bitbucket.org/hgugmradiofisica/pymonaco/src/master/. A study of prostate cancer cases was conducted to compare automatically created plans with previously treated cases. The toolkit fully automated the radiotherapy planning procedure, allowing the TPS to calculate or optimize plans during nonworking hours. In the prostate study, the use of this tool reduced the dose to organs at risk with a negligible decrease in target coverage. This tool enables the efficient use of the TPS, allowing research and clinical applications to coexist without conflict. It provides consistency and efficiency throughout the treatment planning process, which may be of great value to clinics with few resources. The impact of this tool on clinical workflow is important, as it not only provides better efficiency, but also increases treatment quality. 相似文献
5.
IntroductionThis report evaluates whether health related quality of life (HRQoL) and patient-reported arm morbidity one year after axillary surgery are affected by the omission of axillary lymph node dissection (ALND).MethodsThe ongoing international non-inferiority SENOMAC trial randomizes clinically node-negative breast cancer patients (T1-T3) with 1–2 sentinel lymph node (SLN) macrometastases to completion ALND or no further axillary surgery. For this analysis, the first 1181 patients enrolled in Sweden and Denmark between March 2015, and June 2019, were eligible. Data extraction from the trial database was on November 2020. This report covers the secondary outcomes of the SENOMAC trial: HRQoL and patient-reported arm morbidity. The EORTC QLQ-C30, EORTC QLQ-BR23 and Lymph-ICF questionnaires were completed in the early postoperative phase and at one-year follow-up. Adjusted one-year mean scores and mean differences between the groups are presented corrected for multiple testing.ResultsOverall, 976 questionnaires (501 in the SLN biopsy only group and 475 in the completion ALND group) were analysed, corresponding to a response rate of 82.6%. No significant group differences in overall HRQoL were identified. Participants receiving SLN biopsy only, reported significantly lower symptom scores on the EORTC subscales of pain, arm symptoms and breast symptoms. The Lymph-ICF domain scores of physical function, mental function and mobility activities were significantly in favour of the SLN biopsy only group.ConclusionOne year after surgery, arm morbidity is significantly worse affected by ALND than by SLN biopsy only. The results underline the importance of ongoing attempts to safely de-escalate axillary surgery.Trial registrationThe trial was registered at clinicaltrials.gov prior to initiation (https://clinicaltrials.gov/ct2/show/NCT 02240472). 相似文献
6.
7.
8.
9.
10.
《Respiratory investigation》2021,59(6):837-844
BackgroundUnilateral upper-lung field pulmonary fibrosis (upper-PF), which is radiologically consistent with pleuroparenchymal fibroelastosis, develops after thoracic surgery. In most patients with unilateral upper-PF, aberrant intra-/extra thoracic air commonly emerges and an autopsy shows chronic pleuritis, which indicates that pleural involvement is associated with upper-PF development. If so, there may be patients with unilateral upper-PF who have a history of pleural involvement, including tuberculous pleurisy (TP) or asbestos exposure (AE). This study aimed to examine this supposition.MethodsWe examined the radiological reports of all consecutive patients from 2012 to 2018 to investigate whether there were patients having unilateral upper-PF and a history of TP or AE.ResultsEight patients were included in the study. Five patients had a history of TP, and the remaining three had that of AE. All patients were men and had respiratory symptoms, and seven patients presented with restrictive ventilatory impairment. The interval between TP or last AE and upper-PF development was long, with a median of over 20 years. The upper-PF lesion was commonly located in the right lung, and aberrant intrathoracic air was observed in five patients during their clinical course. Additionally, the upper-PF lesion transformed into a cystic lesion in six patients, which resulted in Aspergillus infection in two patients. The prognosis was poor, with a median overall survival of 38 months.ConclusionsUnilateral upper-PF developed even in patients with a history of pleural involvement. Our results indicate that pleural involvement plays an important role in the development of unilateral upper-PF. 相似文献