全文获取类型
收费全文 | 25960篇 |
免费 | 1590篇 |
国内免费 | 459篇 |
专业分类
耳鼻咽喉 | 127篇 |
儿科学 | 85篇 |
妇产科学 | 43篇 |
基础医学 | 1610篇 |
口腔科学 | 1657篇 |
临床医学 | 2274篇 |
内科学 | 1087篇 |
皮肤病学 | 25篇 |
神经病学 | 338篇 |
特种医学 | 1503篇 |
外国民族医学 | 2篇 |
外科学 | 10296篇 |
综合类 | 4947篇 |
现状与发展 | 1篇 |
预防医学 | 879篇 |
眼科学 | 156篇 |
药学 | 1635篇 |
55篇 | |
中国医学 | 1152篇 |
肿瘤学 | 137篇 |
出版年
2024年 | 264篇 |
2023年 | 523篇 |
2022年 | 990篇 |
2021年 | 1234篇 |
2020年 | 1221篇 |
2019年 | 882篇 |
2018年 | 743篇 |
2017年 | 870篇 |
2016年 | 978篇 |
2015年 | 903篇 |
2014年 | 1882篇 |
2013年 | 1880篇 |
2012年 | 1727篇 |
2011年 | 1872篇 |
2010年 | 1551篇 |
2009年 | 1477篇 |
2008年 | 1256篇 |
2007年 | 1255篇 |
2006年 | 1115篇 |
2005年 | 1055篇 |
2004年 | 858篇 |
2003年 | 636篇 |
2002年 | 474篇 |
2001年 | 438篇 |
2000年 | 317篇 |
1999年 | 306篇 |
1998年 | 214篇 |
1997年 | 203篇 |
1996年 | 148篇 |
1995年 | 133篇 |
1994年 | 93篇 |
1993年 | 82篇 |
1992年 | 63篇 |
1991年 | 44篇 |
1990年 | 33篇 |
1989年 | 24篇 |
1988年 | 26篇 |
1987年 | 26篇 |
1986年 | 23篇 |
1985年 | 19篇 |
1984年 | 17篇 |
1983年 | 24篇 |
1982年 | 30篇 |
1981年 | 25篇 |
1980年 | 14篇 |
1979年 | 13篇 |
1978年 | 14篇 |
1977年 | 7篇 |
1976年 | 9篇 |
1975年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
2.
3.
《Neuro-Chirurgie》2021,67(4):350-357
IntroductionAnterior odontoid screw fixation is a valid surgical option for unstable odontoid fractures, as type II Anderson D’Alonzo fractures. Grauer further divided type II fractures in subtypes according to the fracture line, providing recommendations for implementation of screw fixation techniques.ObjectivePrimary endpoint of our study is to evaluate the postoperative results of minimally invasive odontoid screw insertion in terms of outcome, fusion rate and stability of cranio-cervical junction. Secondary endpoint was to investigate the influence of age or fractures’ features on outcome and fusion rate.Materials and methodsWe report the clinical and radiological features of 32 patients harbouring unstable type II fractures operated by a minimally invasive odontoid screw insertion technique. All patients underwent a high resolution multiplanar CT in order to assess fracture features according to Grauer's classification; the integrity of ligaments was investigated by MRI. In addition, a preoperative neurological performance (modified Rankin Scale, mRS) was evaluated for patients either directly or interviewing their families. Follow-up at one, three and six months and 1 year have been performed (averaging 13.5 months) by cervical CT (fusion rate and stability) and mRS update. In order to investigate the influence of age on postoperative neurological performance, two groups (≤ 50 yrs, 9 pts/ > 50 yrs, 23 pts) were separately considered and analysed. Overall, we observed no surgery related complications. We also analysed the fusion rate and its correlation with patient age and Grauer's subtype of fracture.ResultsAt last available clinical follow-up, the preoperative performance was preserved (mRS 0/1: 24, 75%; mRS 2–4: 9, 15%) although with slight reduction of intact patients (mRS 0: 22 vs. 19; 71.8 vs. 59.3%). Younger patients (≤ 50 yrs) fared significantly better than older ones, achieving a good clinical outcome (mRS 0/1) in 100% vs. 69.5% (9/9 vs. 16/23 pts). Statistical analysis showed a fair correlation between age and outcome. Other factors such as sex and Grauer's type did not influence significantly the clinical outcome. Nine patients did not complete a full radiological follow-up and were therefore excluded from analysis of radiological outcome. Among the remaining 23 patients, only 25% of those who were followed three months or less showed fusion; conversely, all patients who have been examined from 6 to 48 months fused. Among the non-union patients, two underwent a second surgery by posterior approach.ConclusionsIn our recent experience, the minimally invasive AOSF proved safe and effective in treating odontoid peg fractures. Selection based on Grauer's type is mandatory to achieve best results. While in the elderly, an anterior approach is well accepted as the first choice treatment, we recommend that this option should be offered as a suitable alternative to Halo or orthosis also in younger patients since it provides prompt, excellent clinical outcome and high fusion rate especially in this age group. 相似文献
4.
目的探讨带线锚钉在手术治疗肘关节"恐怖三联征"中的临床效果。方法回顾性分析2010年1月至2017年6月期间本院手术治疗22例肘关节"恐怖三联征"患者的临床资料,根据桡骨头骨折Mason分型,Ⅰ型2例,Ⅱ型8例,Ⅲ型12例;根据尺骨冠状突骨折Regan-Morrey分型,Ⅰ型5例,Ⅱ型12例,Ⅲ型5例;22例患者均伴有内外侧副韧带损伤,并采用肘部外侧、前内侧联合入路进行手术治疗。15例患者手术后以长臂石膏托外固定1~2周,之后逐步进行肘关节被动、主动康复锻炼。7例使用可活动铰链式外固定架辅助固定的患者早期行肘关节康复锻炼。结果所有患者手术后随访6~18个月,平均12个月。末次随访时肘关节屈曲(110±10)°,伸直受限(10±4)°,前臂旋前(70±6)°,旋后(80±6)°,并对患者进行Mayo肘关节功能评分:优(≥90分)3例,良(75~89分)12例,可(60~74分)7例,优良率为68.2%。手术后2例出现异位骨化,1例出现一过性的正中神经症状,无感染、肘关节不稳定、骨折不愈合、脱位及肘关节僵硬等并发症。结论带线锚钉通过对肘关节内外侧副韧带、关节囊等软组织修复,既增加了肘关节的稳定性,同时也减少了相关并发症的发生,值得临床推广应用。 相似文献
5.
Kokubo Y Tsumita M Sakurai S Torizuka K Vult von Steyern P Fukushima S 《Journal of oral rehabilitation》2007,34(7):503-507
This study evaluated the fracture loads of three-unit all-ceramic bridges on implants; the core frameworks of the bridges were made of zirconium oxide. Three core framework designs were fabricated according to the design of the bars between the retainers: (i) straight, (ii) curved in the occlusal direction, or (iii) curved in the gingival direction. A static load was applied at the centre of the pontic, and the mean initial crack and final fracture loads were measured and compared. The core framework curved in the occlusal direction had the highest final fracture loads; there were significant differences (P < 0.05) in the mean final fracture load, whereas initial fracture load, which fractured of veneered porcelain, did not show significant differences among three designs. The all-ceramic bridges on the implants made with Procera zirconium core frameworks had high final fracture load. The core framework design that curved in the occlusal direction helped the framework withstand the occlusal load, which results in reliable prostheses, especially in the molar region. 相似文献
6.
Nakamura T Ohyama T Imanishi A Nakamura T Ishigaki S 《Journal of oral rehabilitation》2002,29(10):951-955
The aim of the present study was to evaluate the mechanical strength of the Empress2 system, which is based on the use of a high-strength glass--ceramic core of lithium disilicate, and the fracture resistance of fixed partial dentures fabricated with this material. To evaluate mechanical strength, four types of ceramic materials were tested for four-point flexural strength and diametral tensile strength: Empress2 core material, Empress2 layering porcelain, conventional Empress material and Dicor. Then, using Empress2, conventional Empress and Dicor, actual clinical type anterior fixed partial dentures were fabricated for fracture testing. The results showed that the Empress2 core material, at 329 MPa, has more than twice the flexural strength of conventional materials and at 271 MPa, more than four times the diametral tensile strength of conventional materials. Furthermore, fixed partial dentures fabricated with Empress2 had a fracture resistance of 1424 N. That is, they were more than twice as fracture resistant as fixed partial dentures made with conventional materials. 相似文献
7.
Aim: The aim of this study was to evaluate the prognosis of subluxated, luxated and root fractured teeth in children treated by removable splints, designed to stabilize mobile anterior teeth and eliminate occlusal trauma due to malocclusion. Material and methods: A total of 227 traumatized anterior teeth (91 subluxated, 105 luxated and 31 root fractured teeth) treated with a removable splint were observed for 3 years. The traumatized teeth were from 79 children aged between 6–12 years (mean 8 years 5 months). If a traumatized tooth was extremely mobile, a fixed splint was first made before the impression was taken for the removable splint. Two weeks after completion of the removable splint treatment, an impression was taken again to evaluate the occlusal relationship of pre‐ versus post‐treatment of removable splint. Results: The treatment period with a removable splint averaged 3 weeks in subluxated teeth, 3–5 weeks in luxated teeth, 4–6 weeks in apical third root fracture injuries, and more than 5 weeks in middle third root fracture injuries. All the subluxated teeth and 74.1% of the luxated teeth maintained their pulp vitality during the 3‐year follow‐up period. Two of 21 (9.5%) apical third root fracture teeth and three of five (60%) middle third root fracture teeth had pulp necrosis in the coronal fragments. Internal resorption was not found in any of the traumatized teeth. External replacement resorption was not found in subluxated and luxated teeth. All the root fractured teeth displayed transient external resorption around the fracture lines. The surface resorption appeared to be self‐limiting and not to threaten the retention of the tooth. Inflammatory resorption was observed in teeth with pulp necrosis, but in all cases this was reversed with endodontic treatment. Eight of 23 (39%) apical third root fractured teeth displayed replacement resorption in their apical fragments, but the resorption was not serious enough to extract the tooth. No obvious alteration in the occlusal relationship was found comparing pre‐ and post‐treatment casts. The removable splints appeared to positively affect healing after traumatic injuries, as evidenced by the low number of complications at the 3‐year follow‐up period. 相似文献
8.
Introduction
The aim of this in vitro study was to evaluate the fracture type and test the effects of 2 different fibers on fracture strength of roots with reattached fragments. The null hypothesis was that adding suitable fibers to the content of dual-cure adhesive resin cement increases the fracture resistance of reattached fragments under vertical forces.Methods
Root canals of 45 teeth were prepared, and the teeth were intentionally fractured into 2 separate fragments. Control groups (n = 7 each) consisted of unfractured teeth with instrumented and obturated or only instrumented root canals. The fractured teeth were divided into 3 groups (n = 15 each), and separated fragments were reattached by using (1) dual-cured resin cement (Clearfil SA), (2) dual-cured resin cement + polyethylene fiber (Construct), or (3) dual-cured resin cement + glass fiber (Stick-Net). Force was applied at a constant speed of 0.5 mm/min to the root until fracture. Mean load was recorded and analyzed statistically by using Kruskal-Wallis and Dunn tests (P = .05). Fracture types were analyzed by using χ2 analysis with Yates correction.Results
Stick-Net demonstrated the lowest fracture resistance (P < .05), whereas Construct and Clearfil SA had similar fracture strengths (P > .05). The roots in the control group showed the highest fracture resistance. However, there was no statistically significant difference between the Construct, Clearfil SA, and control groups (P > .05).Conclusions
Separated fragments of vertically fractured teeth can be reattached by using a dual-cured resin or by adding polyethylene fiber (Construct). 相似文献9.
Fracture characteristics of carbon fibre, ceramic and non-palladium endodontic post systems at monotonously increasing loads 总被引:8,自引:0,他引:8
A carbon fibre post system, three non-palladium and one palladium metal post systems, two ceramic post systems, and a metal post system with a ceramic core were studied in vitro. The control group consisted of root-filled test teeth without posts. The test teeth were identical artificial roots of an upper central incisor made from a posterior composite whose module of elasticity was similar to that of natural dentine. All posts were cemented in the roots using Panavia 21 TC. Subsequently, standardized full crowns were cemented onto all roots. On a universal testing machine, the test teeth were loaded palatally at monotonously increasing loads until root fracture. The highest mean fracture loads were found for the carbon fibre post system (312.5 +/- 58.8 N). The fracture load of non-palladium metal posts (242.3-300.4 N) did not differ significantly from that of the Perma-dor post (265.9 N), which does contain palladium. Values of 300.3 +/- 89.3 N (aluminium oxide ceramics) and 193.5 +/-57.0 N (zirconia ceramics) were found for the ceramic posts. The control group exhibited a fracture load of 228.8 +/- 35.7 N. The mean distance between the vestibular end of the fracture gap and the point of force application was between 10.1 +/- 2.3 and 14.7 +/- 1.2 mm. 相似文献
10.
AIMS: This study investigated the effect of stainless steel bands on cuspal flexure and fracture resistance of extracted maxillary premolars. METHODOLOGY: Twenty extracted maxillary premolars (10 matched pairs) with mesio-occluso-distal (MOD) cavities and endodontic access were subjected to occlusal loading tests (100 N) using a servo-hydraulic testing machine. Cuspal deflections were measured by an extensometer, with and without the band present. Ten teeth (one of each pair) then had the band removed, and all teeth were subjected to loading until fracture. RESULTS: Mean cuspal flexure of teeth with bands was one-half of flexure without bands (P < 0.001). Teeth with bands fractured at higher load than their matched pairs with the band removed (P < 0.001), with mean loads at fracture of 1282 N and 729 N, respectively. CONCLUSIONS: The study showed that stainless steel bands used in endodontics reduce the cuspal flexure of maxillary premolars and increase their fracture resistance. 相似文献