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   40838篇
  免费   4123篇
  国内免费   1990篇
耳鼻咽喉   795篇
儿科学   1046篇
妇产科学   194篇
基础医学   5362篇
口腔科学   7113篇
临床医学   3651篇
内科学   3587篇
皮肤病学   160篇
神经病学   890篇
特种医学   2065篇
外国民族医学   20篇
外科学   8967篇
综合类   6158篇
现状与发展   6篇
预防医学   1266篇
眼科学   154篇
药学   1927篇
  22篇
中国医学   1311篇
肿瘤学   2257篇
  2024年   70篇
  2023年   619篇
  2022年   999篇
  2021年   1586篇
  2020年   1631篇
  2019年   1482篇
  2018年   1346篇
  2017年   1462篇
  2016年   1420篇
  2015年   1608篇
  2014年   2591篇
  2013年   3660篇
  2012年   2137篇
  2011年   2489篇
  2010年   2209篇
  2009年   2041篇
  2008年   1948篇
  2007年   1991篇
  2006年   1793篇
  2005年   1736篇
  2004年   1552篇
  2003年   1377篇
  2002年   1164篇
  2001年   1032篇
  2000年   848篇
  1999年   757篇
  1998年   622篇
  1997年   617篇
  1996年   579篇
  1995年   408篇
  1994年   424篇
  1993年   294篇
  1992年   310篇
  1991年   254篇
  1990年   206篇
  1989年   204篇
  1988年   163篇
  1987年   130篇
  1986年   127篇
  1985年   154篇
  1984年   111篇
  1983年   108篇
  1982年   124篇
  1981年   91篇
  1980年   86篇
  1979年   88篇
  1978年   93篇
  1977年   62篇
  1976年   60篇
  1975年   36篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
141.
Anterior lumbar fusion using a hybrid interbody graft   总被引:3,自引:0,他引:3  
Summary This is a radiographic report of 40 patients (20 men, 20 women) who underwent anterior lumbar interbody fusions (73 levels) utilizing a “hybrid” interbody graft composed of femoral cortical allograft (FCA) bone and iliac crest cancellous autograft bone. The average age at surgery was 38 years (range 17–64 years), and follow-up averaged 1.4 years (range 1.0–2.4 years). Nineteen of the patients had undergone previous lumbar surgery. Thirty-two patients (63 levels) underwent anterior fusion combined with some type of posterior fixation, and eight patients (10 levels) had no posterior fixation. Types of posterior fixation included: for 20 patients (36 levels) Steffee variable screw placement fixation, for 10 patients (23 levels) translaminar facet screws (TFS), for 1 patient (3 levels) Knodt rods and for 1 patient (1 level) facet screws. Based on the persistence of lucent lines at the graft-host interface, three patients (one level each) were felt to have non-unions at their latest follow-ups at 1.4, 1.5 and 2.0 years, respectively. Two of these patients had no posterior fixation, and the other had TFS fixation. The overall fusion rate was 96% (70 of 73 levels). The fusion rate for all levels treated with posterior fixation was 98% compared with 75% for those without fixation. Intervertebral disc heights (IVDH) were measured on all films and corrected for magnification with computer assistance. On average, the IVDH was increased postoperatively but returned to preoperative values at follow-up. IVDH loss was independent of the type of instrumentation used. No complications arose from the use of the hybrid graft. Incorporation of the allograft portion of the graft is slow and was felt to be complete in only 7 of the 73 levels at follow-up. We conclude that the hybrid interbody graft technique is a safe and reliable method for performing anterior lumbar interbody fusions and should be combined with some type of posterior fixation. Long-term follow-up will be required to assess the behaviour of the allograft until incorporation is complete.  相似文献   
142.
We describe a patient with severe combined immunodeficiency and transplacental transfer of maternal T cells who received an unfractionated HLA-identical sibling bone marrow transplant without prior conditioning. He presented prior to transplantation with a dermatitis later diagnosed as mild graft versus host disease. He had a normal absolute lymphocyte count, but proliferative responses to mitogens were very low. Antigens of the noninherited maternal HLA haplotype were detected on his blood lymphocytes. After transplantation, he developed a severe reaction including fever, cutaneous erythema and hepatosplenomegaly. Lymphocytes carrying the noninherited maternal HLA haplotype disappeared from his circulation, and his unprimed mononuclear cells became spontaneously cytotoxic to maternal lymphoblasts. He subsequently developed a lymphocytosis of 69,000/mm3, diarrhea, elevated transaminases and a worsening rash, necessitating treatment with immunosuppressive agents. Full T-cell engraftment and evidence of B-cell function later ensued and spontaneously cytotoxic lymphocytes against maternal cells disappeared by 47 days post-transplantation. We postulate that the patient's constellation of signs and symptoms after transplantation represented a combination of severe graft versus graft and mild graft versus host reactions.  相似文献   
143.
144.
6例肺癌患者接受了大剂量卡铂并自体骨髓移植治疗 ,卡铂剂量从 5 60~ 1375 mg/ m2 ,5例加用 VP~ 1630 0 mg,1例并用 MMC6mg和 VCR2 mg;主要毒性反应为白细胞、中性粒细胞、血小板减少和脱发 ( WHO毒性反应 ~ 级 )其次是贫血、皮肤粘膜出血、呕吐和可逆性肝功能损害 ,口腔粘膜溃疡及轻度发烧各 2例 ,一过性蛋白尿、室上性心动过速和便秘各 1例 ,尿素氮和肌酐未见升高 ;全部患者骨髓均获解救 ,从自体骨髓回输到骨髓造血功能重建成功平均 2 6.67( 17~ 32 )天  相似文献   
145.
A novel gene therapy approach for treating damaged cartilage is proposed that involves placing endotoxin-free cDNA containing the gene for bone morphogenetic protein-2 (BMP-2) in type I collagen sponges and then transferring the naked plasmid DNA construct to the injury site. A full-thickness cartilaginous defect in rabbits implanted with plasmid containing a marker gene (beta-galactosidase) showed expressed protein as detected by immunostaining. At 1 week postimplantation, mesenchymal cells subjacent to the defect had incorporated the implanted naked plasmid DNA and, once transfected, served as local bioreactors, transiently producing the gene product. Plasmids containing the gene for BMP-2 implanted in collagen sponges in cartilage lesions stimulated hyalinelike articular cartilage repair at 12 weeks postimplantation, nearly equivalent in quality to that induced by collagen sponges with recombinant BMP-2 protein. Our approach circumvents the risks of inflammation and immunogenic response associated with the use of viral vectors. Naked plasmid DNA as a vehicle for transferring therapeutic genes has been shown to be effective in a therapeutic model within rabbit articular cartilage and appears to be safe and cost effective.  相似文献   
146.
带血管蒂跗骨瓣移位术修复踝及足部骨病损   总被引:6,自引:2,他引:4  
目的 为治疗踝及足部骨质病损提供系列手术方式。方法 在解剖学研究基础上,设计了带血管蒂的骰骨瓣、内侧楔骨瓣、舟骨瓣和跟骨前外侧骨瓣移位术,以修复踝及足骨质病损。临床应用55例。结果 术后经l—10年随访48例,平均为4年6个月,疗效满意。结论 上述4种跗骨瓣均具有血管蒂位置表浅、解剖容易和手术安全可靠等优点。  相似文献   
147.
Improved anchorage in osteoporotic vertebrae with new implant designs.   总被引:2,自引:0,他引:2  
The goal of our study was to evaluate two newly developed implant designs and their behavior in terms of subsidence in lumbar vertebral bodies under cyclic loading. The new implants were evaluated in two different configurations (two small prototypes vs. one large prototype with similar load-bearing area) in comparison to a conventional screw-based implant (MACS TL). A pool of 13 spines with a total of 65 vertebrae was used to establish five testing groups of similar bone mineral density (BMD) distribution with eight lumbar vertebrae each. In additional to BMD assessment via dual-energy X-ray absorptiometry, cancellous BMD and structural parameters were determined using a new generation in vivo 3D-pQCT. The specimens were loaded sinusoidally in force control at 1 Hz for 1000 cycles at three load levels (100, 200, and 400 N). A survival analysis using the number of cycles until failure (Cox regression with covariates) was applied to reveal differences between implant groups. All new prototype configurations except the large cylinder survived significantly longer than the control group. The number of cycles until failure was significantly correlated with the structural parameter Tb.Sp. and similarly with the cancellous BMD for three of five implants. In both large prototypes the cycle number until failure significantly correlated with the preoperative distance to the upper endplates. Although the direct relationship between bone structure or density and mechanical breakage behavior cannot be conclusively proven, all the prototypes adapted for poor bone structure performed better than the comparable conventional implant.  相似文献   
148.
目的:探讨骨巨细胞瘤术后复发的手术方法及疗效。方法:1994年6月-2003年10月,收治四肢长骨复发性骨巨细胞瘤18例,男12例,女6例;年龄18~44岁,平均26岁。股骨下端5例,胫骨上端8例,股骨上端1例,桡骨远端4例。Enneking分期:Ⅰa期14例,Ⅰb期4例。放射影像学Cam-panicci分级:Ⅰ级7例,Ⅱ级7例,Ⅲ级4例。病理学Jaffe分级:Ⅰ级8例,Ⅱ级7例,Ⅲ级3例。采用肿瘤扩大切除,吻合血管的自体腓骨、髂骨联合移植术治疗9例;瘤段切除,吻合血管的腓骨头移植重建术4例;瘤段切除,人工假体置换术5例。结果:随访时间11~110个月,平均66个月。所有移植骨术后均愈合,一侧关节间隙轻度狭窄2例,术后再复发1例。术后功能评价:优13例,良3例,可1例,差1例。结论:肿瘤扩大切除,吻合血管的自体腓骨、髂骨联合移植术既能彻底切除病变,又能保持和重建关节功能,是一种较理想的方法,Campanicci分级Ⅲ级、病理学Jaffe分级Ⅱ~Ⅲ级的复发性骨巨细胞瘤原则上应施行更为广泛的瘤段切除术,桡骨远端复发性骨巨细胞瘤因其部位的特殊性,应用自体腓骨移植重建效果良好。  相似文献   
149.
目的研究生物衍生骨与骨髓基质干细胞(marrow stromal stem cells, MSCs)复合修复山羊胫骨缺损的血管化过程,了解其修复长段管状负重骨缺损的血管化情况. 方法制备生物衍生骨作为支架材料,培养、诱导MSCs作为种子细胞,二者在体外复合构建组织工程骨.20只山羊双侧胫骨中段制备成20 mm长的骨-骨膜缺损模型,采取自身左右侧对照,实验侧(右侧)缺损处植入组织工程骨,对照侧(左侧)植入单纯支架材料,采用钢板内固定.术后2、4、6及8周用墨汁灌注透明标本及血管面积图像分析方法观察血管化过程,组织学观察血管形成及成骨情况. 结果术后2、4周,实验侧血管形成较对照侧少(P<0.05);术后8周,两侧均完全血管化,差异无统计学意义(P>0.05).实验侧于术后6、8周新骨形成逐渐增加,材料降解吸收较对照组快;对照侧术后8周材料孔隙内仍无明显新骨形成. 结论生物衍生骨作为骨组织工程的支架材料,能够较快发生血管化;组织工程骨成骨能力较单纯支架材料强.  相似文献   
150.
股骨远端复杂骨折的手术治疗   总被引:13,自引:4,他引:9  
目的探讨股骨远端严重粉碎骨折有效治疗方法. 方法在动物实验基础上,我们于2001年3月~2002年8月,应用AO髁支持钢板及自行设计翼状解剖型钢板内固定与同种异体骨移植治疗股骨远端复杂骨折26例,均为AO/ASIF分类中33C3.3.采用AO技术,术中平均植骨46 g. 结果术后24例伤口Ⅰ期愈合,2例伤口感染经换药愈合.24例4~11个月达到骨性愈合,2例过早负重致固定失败而再次手术.随访7~25个月,平均14个月,根据Shelbourne and Brueckmann膝关节功能评定标准,优5例,良18例,可1例,差2例,优良率为88.5%. 结论翼状解剖型钢板远端螺钉孔为长椭圆形且有连续钉孔,适合于严重粉碎骨折;翼状解剖型钢板及髁支持钢板内固定与充分植骨是治疗股骨远端复杂骨折较理想的方法,同种异体骨可以取代自体髂骨植骨.  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