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   3788篇
  免费   215篇
  国内免费   91篇
耳鼻咽喉   13篇
儿科学   103篇
妇产科学   60篇
基础医学   475篇
口腔科学   124篇
临床医学   312篇
内科学   849篇
皮肤病学   35篇
神经病学   216篇
特种医学   68篇
外科学   550篇
综合类   305篇
一般理论   5篇
预防医学   373篇
眼科学   52篇
药学   214篇
  4篇
中国医学   90篇
肿瘤学   246篇
  2023年   21篇
  2022年   56篇
  2021年   69篇
  2020年   68篇
  2019年   56篇
  2018年   64篇
  2017年   60篇
  2016年   54篇
  2015年   90篇
  2014年   115篇
  2013年   170篇
  2012年   240篇
  2011年   245篇
  2010年   171篇
  2009年   204篇
  2008年   216篇
  2007年   237篇
  2006年   179篇
  2005年   153篇
  2004年   162篇
  2003年   141篇
  2002年   131篇
  2001年   78篇
  2000年   75篇
  1999年   90篇
  1998年   35篇
  1997年   45篇
  1996年   46篇
  1995年   31篇
  1994年   40篇
  1993年   40篇
  1992年   65篇
  1991年   53篇
  1990年   50篇
  1989年   39篇
  1988年   42篇
  1987年   33篇
  1986年   24篇
  1985年   26篇
  1984年   27篇
  1983年   29篇
  1982年   19篇
  1980年   19篇
  1979年   29篇
  1978年   30篇
  1977年   24篇
  1976年   25篇
  1975年   20篇
  1974年   24篇
  1971年   19篇
排序方式: 共有4094条查询结果,搜索用时 15 毫秒
41.

Background and purpose

We performed a randomized study to determine the migration patterns of the Spectron EF femoral stem and to compare them with those of the Charnley stem, which is regarded by many as the gold standard for comparison of implants due to its extensive documentation.

Patients and methods

150 patients with a mean age of 70 years were randomized, single-blinded, to receive either a cemented Charnley flanged 40 monoblock, stainless steel, vaquasheen surface femoral stem with a 22.2-mm head (n = 30) or a cemented Spectron EF modular, matte, straight, collared, cobalt-chrome femoral stem with a 28-mm femoral head and a roughened proximal third of the stem (n = 120). The patients were followed with repeated radiostereometric analysis for 2 years to assess migration.

Results

At 2 years, stem retroversion was 2.3° and 0.7° (p < 0.001) and posterior translation was 0.44 mm and 0.17 mm (p = 0.002) for the Charnley group (n = 26) and the Spectron EF group (n = 74), respectively. Subsidence was 0.26 mm for the Charnley and 0.20 mm for the Spectron EF (p = 0.5).

Interpretation

The Spectron EF femoral stem was more stable than the Charnley flanged 40 stem in our study when evaluated at 2 years. In a report from the Norwegian arthroplasty register, the Spectron EF stem had a higher revision rate due to aseptic loosening beyond 5 years than the Charnley. Initial stability is not invariably related to good long-term results. Our results emphasize the importance of prospective long-term follow-up of prosthetic implants in clinical trials and national registries and a stepwise introduction of implants.Femoral stem loosening in cemented total hip arthroplasty (THA) is a multifactorial process with different mechanisms (Gruen et al. 1979, Barrack 2000). Factors such as the material, design, and surface finish are of fundamental importance for the long-term performance of cemented femoral hip implants (Scheerlinck and Casteleyn 2006). The longevity of cemented femoral stems has been related to the quality, stability, and endurance of the bonding between stem and cement (Chang et al. 1998, Scheerlinck and Casteleyn 2006). Different femoral stem designs have been developed to obtain increased fixation at this interface, since debonding between the cement and stem is an important mechanism in the initiation of loosening (Jasty et al. 1991).The satin-finish Spectron femoral stem has been one of the best performing stems in the Swedish National Arthroplasty Register (Malchau et al. 2002). A modified, proximally roughened version of the Spectron stem, the Spectron EF (Smith and Nephew, Memphis, TN), was introduced in 1989 to enhance stem-cement bonding.The use of this implant gained increasing popularity, and in 2007 the Spectron EF stem used with the Reflection All-Poly acetabular cup (Smith and Nephew) was the most commonly used primary total hip prosthesis in Norway (Espehaug et al. 2009).The degree of migration during the first years after surgery has been shown to correlate with the long-term performance of joint prostheses (Kärrholm et al. 1994, Kobayashi et al. 1997). Radiostereometric analysis (RSA) allows the accurate measurement of implant movement and has been extensively used for measurement of the in vivo migration of implants (Kärrholm et al. 1997).An earlier prospective randomized study reported an increased revision rate of the Charnley stem compared to the satin-finished Spectron stem (Garellick et al. 1999). In the present randomized, controlled clinical trial we wanted to evaluate the early migration of the successor to this stem, the Spectron EF stem and to compare it to that of the Charnley stem using RSA. The null hypothesis was that the migration of the Spectron EF stem was equal to that of the Charnley prosthesis (DePuy International Ltd., Leeds, UK), which has the longest follow-up and the largest volume of documentation of implants used for primary total hip arthroplasty (Aamodt et al. 2004).  相似文献   
42.
高位腰椎间盘突出症   总被引:2,自引:0,他引:2  
目的:通过147例高位腰椎间盘突出症的回顾性研究,旨在提高对本症的认识,减少漏诊,误诊,方法:回顾性分析报告147例高位腰椎间盘突出,结果:治疗腰1,210例,腰2。3 32例,腰3,4 105例,其中双间隙突出34例,跳跃性突出27例,伴椎管狭窄31例。瘫痪3例,非手术治疗34例,手术113例,优47例,良8例,差92例,重点讨论了高位腰椎及椎间盘和神经根的解剖特点和临床三大特征及诊断治疗,提出对不同程度的病人用不同治疗方式以及手术中需要注意的六个问题。  相似文献   
43.
目的 探讨内镜辅助腹腔镜(双镜)手术在早期结肠癌治疗中的应用价值.方法 回顾性分析2002年3月至2007年12月间应用双镜手术治疗55例早期结肠癌患者的临床资料.结果 53例成功实施内镜定位、腹腔镜游离结肠肠段切除术,根据术中冰冻病理切片结果追加腹腔镜根治术11例;2例(3.6%)内镜定位后因小肠胀气中转开腹.平均手术时间90(55~240)min,术中平均出血量50(10~200)ml.51例(92.7%)术后2~3 d肛门排气,术后平均住院时间为5(2~15)d,无术后并发症.术后平均随访42(3~72)个月,除1例死于心肌梗死外,其余存活至今,均无肿瘤复发转移.结论 内镜辅助腹腔镜手术可充分发挥两者的优势,是早期结肠癌有效的治疗方法之一.  相似文献   
44.
We studied the rates of revision for 53,698 primary total hip replacements (THRs) in nine different groups of disease. Factors which have previously been shown to be associated with increased risk of revision, such as male gender, young age, or certain types of uncemented prosthesis, showed important differences between the diagnostic groups. Without adjustment for these factors we observed an increased risk of revision in patients with paediatric hip diseases and in a small heterogeneous 'other' group, compared with patients with primary osteoarthritis. Most differences were reduced or disappeared when an adjustment for the prognostic factors was made. After adjustment, an increased relative risk (RR) of revision compared with primary osteoarthritis was seen in hips with complications after fracture of the femoral neck (RR = 1.3, p = 0.0005), in hips with congenital dislocation (RR = 1.3, p = 0.03), and in the heterogenous 'other' group. The analyses were also undertaken in a more homogenous subgroup of 16,217 patients which had a Charnley prosthesis implanted with high-viscosity cement. The only difference in this group was an increased risk for revision in patients who had undergone THR for complications after fracture of the femoral neck (RR = 1.5, p = 0.0005). THR for diagnoses seen mainly among young patients had a good prognosis, but they had more often received inferior uncemented implants. If a cemented Charnley prosthesis is used, the type of disease leading to THR seems in most cases to have only a minor influence on the survival of the prosthesis.  相似文献   
45.
目的 探讨以聚羟基乙酸(PGA)包裹特定形态的医用假体材料--多孔高密度聚乙烯(HDPE,商品名为MEDPOR)为支架,应用软骨细胞诱导骨髓基质干细胞(BMSCs),共培养构建特定形态的带内支撑组织工程化软骨医用假体的可能性.方法 以直径3 mm、长5 mm的圆柱形HDPE,外裹 1 mm厚PGA为支架,将体外分别培养的新生猪BMSCs和耳郭软骨细胞按7∶3混合,以10×10 7/ml细胞浓度接种于支架上,同时以相同浓度的单纯软骨细胞和单纯BMSCs分别接种,作为阳性对照组(PC组)和阴性对照组(NC组).经体外培养2周及在裸鼠皮下移植4、8周后取材 ,行大体观察、组织学、组织化学及免疫组化检测.结果 各组细胞均与材料黏附良好.实验组和阳性对照组均形成了大体形态良好的HDPE-软骨复合体,内支撑的HDPE与外层软骨结合紧密.组织学可见成熟的软骨陷窝结构,软骨渗入HDPE孔隙内部、异染基质及Ⅱ型胶原呈强阳性表达.结论 以HDPE为内支撑,外裹PGA的支架,接种混合细胞,可于皮下构建特定形态、组织学良好的HDPE-软骨复合体.  相似文献   
46.
Mediastinitis is treated with either vacuum‐assisted closure (VAC) or traditional closed drainage (TCD) with irrigation. The aim of the study was to determine the effect of the two treatments on mortality and re‐infection rate in a source population, using 21 314 consecutive patients undergoing isolated coronary artery bypass grafting (CABG) from January 1997 to October 2010. Median observation time was 2·9 years in the VAC group and 8·0 years in the TCD group. The epidemiological design was of an exposed (VAC, n = 64) versus non‐exposed (TCD, n = 66) cohort with two endpoints: (1) mortality and (2) failure of sternal wound healing or re‐infection. The crude effect of treatment technique versus endpoint was estimated by univariate analysis. Stratification analysis by the Mantel–Haenszel method was performed to quantify confounders and to pinpoint effect modifiers. Adjustment for confounders was performed using Cox regression analysis. Mediastinitis was diagnosed 6–105 (median 14) days after primary operation in the VAC group and 13 (5–29) days in the TCD group. There was no difference between groups in long‐term survival. Failure of sternal wound healing or re‐infection occurred less frequently in the VAC group (6%) than in the TCD group (21%; relative risk = 0·29, 95% CI = 0·06–0·88, P = 0·01). There are concerns for increase in right ventricle rupture in VAC compared with TCD. There was no difference in survival after VAC therapy and TCD therapy of post‐CABG mediastinitis. Failure of sternal wound healing or re‐infection was more common after TCD therapy.  相似文献   
47.
用Gallie术式治疗寰枢关节不稳定的临床问题研究   总被引:1,自引:0,他引:1  
Chen XS  Jia LS  Yuan W  Ye XJ  Chen DY  Zhou XH  Song DW  Qian L  Tan J 《中华外科杂志》2004,42(21):1312-1315
目的研究寰枢椎后路内固定融合术治疗寰枢关节不稳或脱位的相关临床问题。方法回顾138例由创伤或畸形所致的寰枢关节不稳或脱位的外科治疗,其中齿突发育畸形伴寰枢椎脱位62例,齿突骨折或横韧带断裂伴寰枢关节不稳或脱位54例,寰枢椎半脱位伴旋转畸形22例,全部采用Gallie技术,6例合并使用侧块经关节螺钉固定,此6例患者术后采用简易颌胸围领固定,其余患者均采用头颈胸石膏或颌胸石膏固定。随访1~12年,平均3年5个月。结果根据Sumi评价标准:优70例(50.7%),良40例(29.0%),中15例(10.9%),差13例(9.4%)。9例植骨延迟愈合,经加强外固定治愈,2例植骨不愈合者行翻修手术,1例出现脊髓损伤并发症。结论Gallie融合术是治疗寰枢椎不稳或脱位的有效术式,术前的牵引复位及术后可靠的外固定是治疗成功的必要的辅助手段。精细的穿钢丝或钛缆技术、寰椎后弓去皮质、寰枢椎后弓间植骨块维持生理高度是手术成功的关键。寰枢椎后路融合失败者必须在明确适应证和目的的情况下采取翻修手术。  相似文献   
48.
27 patients (aged 15-55 years) with relapsed acute myelogenous (AML) and lymphoblastic leukaemia (ALL), and with lymphoblastic non Hodgkin's lymphoma (NHL) have been treated with intermediate dose cytosine arabinoside (AraC, 1 g/m2 q 12 h X 12) and 3 d of m-AMSA (20 patients), 90-115 mg/m2 daily, or daunorubicin (7 patients). 18 of them attained a complete remission (AML 10/14, ALL 3/5, NHL 5/8). 7 patients received consolidation treatment with 1-2 courses comprising 4 d of AraC (3 g/m2 q 12 h X 8) and m-AMSA (90-115 mg/m2) on d 5 of each course. 2 patients underwent allogeneic bone marrow transplantation and 9 received no further treatment after remission induction. In addition to vomiting, fever and conjunctivitis, toxicity in 6 patients included a combination of severe diarrhoea, fever and signs of paralytic ileus. 3 of them died during the pancytopenic phase. The pancytopenic period ranged from 16-25 d (median 21 d) after the remission induction and 14-21 d (median 19 d) after the consolidation course. Median remission duration was 5 months for those patients who received no treatment after remission induction and greater than 9 months (4+ - 16+ months) for the patients who received consolidation courses. Increased dosages of AraC are active in relapsed leukaemia and lymphoma, although optimal dose and schedule are still undetermined.  相似文献   
49.
关节镜辅助下微创经皮螺钉内固定治疗胫骨平台骨折   总被引:5,自引:0,他引:5  
目的:探讨关节镜辅助下微创经皮螺钉内固定治疗胫骨平台骨折的可行性及疗效。方法:自2001年1月-2005年1月,应用膝关节镜检查及监测下经皮螺钉内固定治疗胫骨平台骨折27例,按照Schatzker分类法:Ⅰ型9例,Ⅱ型8例,Ⅲ型5例,Ⅳ型5例。所有病例均行经皮骨折有限显露复位,适当植骨,应用1~3枚松质骨拉力螺钉内固定,术后配合CPM功能锻炼。结果:本组随访6~24个月,平均15个月。骨折临床愈合时间3~4个月,平均3·5个月。无畸形愈合、感染、螺钉断裂。按Sanders膝关节功能评分法评定结果:优12例,良11例,中3例,差1例,优良率85·2%。结论:关节镜辅助经皮螺钉内固定是治疗胫骨平台骨折的有效方法之一,其对膝关节创伤小,可达解剖复位,固定可靠,患肢功能恢复好,并发症少。  相似文献   
50.
目的探讨枢椎椎板螺钉固定术应用于上颈椎后路融合内固定术中的可行性。方法回顾性分析本院2012年1月—2014年12月在上颈椎后路融合固定术中采用枢椎椎板螺钉固定的19例患者资料,术中根据枢椎椎弓根是否存在缺如、细小等情况,选择置入双侧枢椎椎板螺钉或单侧枢椎椎板螺钉并对侧椎弓根螺钉,联合枕骨板螺钉和/或寰椎侧块螺钉。15例上颈椎畸形患者均有不同程度脊髓功能损害表现,日本骨科学会(JOA)评分为5~15分,平均11.5分。4例外伤性寰枢椎骨折患者有后颈部疼痛及活动障碍,疼痛视觉模拟量表(VAS)评分为2~7分,平均4.5分。术后复查患者影像学资料,观察内固定位置及植骨融合情况。结果所有手术顺利完成,未发生椎动脉、脊髓等损伤。术后复查CT,显示所有枢椎椎板螺钉位置良好,均未突破内侧皮质骨。随访时X线、CT示螺钉位置良好,无松动及断钉。所有患者术后12个月植骨均融合,上颈椎畸形患者神经功能均有不同程度改善,JOA评分为13~17分,平均15.3分。外伤性寰枢椎骨折患者颈部疼痛及活动障碍明显改善,VAS评分为0~2分,平均1.0分。结论枢椎椎板螺钉固定在上颈椎后路固定手术中方法简单安全、效果良好,对于无法行枢椎椎弓根螺钉固定的患者,枢椎椎板螺钉固定是一种安全有效的替代方法。  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