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   69285篇
  免费   6287篇
  国内免费   2403篇
耳鼻咽喉   3695篇
儿科学   1293篇
妇产科学   340篇
基础医学   7418篇
口腔科学   17482篇
临床医学   5745篇
内科学   6073篇
皮肤病学   301篇
神经病学   2133篇
特种医学   2866篇
外国民族医学   20篇
外科学   11452篇
综合类   8797篇
现状与发展   6篇
预防医学   2366篇
眼科学   759篇
药学   2874篇
  41篇
中国医学   1520篇
肿瘤学   2794篇
  2024年   164篇
  2023年   1190篇
  2022年   2035篇
  2021年   2766篇
  2020年   2739篇
  2019年   2794篇
  2018年   2632篇
  2017年   2615篇
  2016年   2607篇
  2015年   2776篇
  2014年   4496篇
  2013年   5800篇
  2012年   3696篇
  2011年   4181篇
  2010年   3517篇
  2009年   3308篇
  2008年   3153篇
  2007年   3245篇
  2006年   2911篇
  2005年   2683篇
  2004年   2358篇
  2003年   2082篇
  2002年   1740篇
  2001年   1531篇
  2000年   1320篇
  1999年   1146篇
  1998年   988篇
  1997年   916篇
  1996年   828篇
  1995年   609篇
  1994年   622篇
  1993年   460篇
  1992年   469篇
  1991年   365篇
  1990年   314篇
  1989年   315篇
  1988年   252篇
  1987年   217篇
  1986年   213篇
  1985年   301篇
  1984年   232篇
  1983年   214篇
  1982年   244篇
  1981年   171篇
  1980年   156篇
  1979年   129篇
  1978年   136篇
  1977年   104篇
  1976年   99篇
  1975年   62篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
122.
BACKGROUND: Graft-vs.-host disease (GVHD) is the major cause of morbidity and mortality in patients undergoing allogeneic Bone Marrow Transplantation (BMT). The aim of our study was to identify the most relevant histological features for diagnosis of chronic Graft-vs.-Host Disease (cGVHD) in oral mucosa and minor salivary glands of 25 patients, as well as to evaluate the immunophenotype of the inflammatory cells. METHODS: Sixteen patients that were submitted to allogeneic BMT but did not present cGVHD were selected as a control group. The sections were studied on H & E and CD68, CD45, CD4, CD8, CD20 staining. RESULTS: The most frequent histologic findings in oral mucosa at the day of diagnosis of cGVHD were: hydropic degeneration of the basal layer of the epithelium, apoptotic bodies, lymphocytic infiltration, and focal or total cleavage between the epithelial and connective tissue. In the labial salivary glands (LSG), lymphocytic infiltration, acinar loss and fibrosis were the main alterations. Cytotoxic CD8-T cells and macrophages were predominant both in the epithelium and connective tissue, as well as in minor salivary glands. CONCLUSIONS: Histological features were useful in the diagnosis of oral cGVHD. It is suggested that CD8-T cells and macrophages play important role in the pathogenesis of the disease.  相似文献   
123.
Cleft closure for the treatment of unhealed perineal sinus   总被引:2,自引:0,他引:2  
OBJECTIVE: Despite improvements in surgical practice, persistent perineal wound sinus is still a common complication after proctectomy. This study presents the success of a modified cleft closure technique in dealing with this problem. METHODS: From May 1997 patients with a persistent perineal sinus after surgery underwent a cleft closure - similar to that performed for patients with pilonidal sinus disease. RESULTS: Eight patients (6 male, 2 female) with an average age of 52 years underwent a cleft closure for a persistent perineal sinus after surgery. Four patients had undergone a proctocolectomy (ulcerative colitis), 2 an abdominoperineal excision of the rectum (adenocarcinoma) and 2 a proctectomy (1 Crohn's disease, 1 complication of diverticular disease). Symptoms had been present for an average of 41 months (range 5-152 months) and 3 patients had undergone other procedures attempted previously to deal with the problem. The first three patients had the procedure as an inpatient with an average stay of 4.7 days. The next 5 patients had the procedure as a day case (2 local anaesthetic, 3 general anaesthetic). Two patients developed a postoperative wound infection and all but one wound had healed completely by 8 weeks. In this patient the procedure was repeated to achieve healing. There was no other associated morbidity and no postoperative deaths. There have been no recurrences to date. CONCLUSION: Modified cleft closure for persistent perineal sinus is a simple procedure with low morbidity that can be performed under local anaesthetic in the day surgery unit.  相似文献   
124.
神经化组织工程骨构建的初步观察   总被引:16,自引:0,他引:16  
目的评估两种组织工程骨体内神经化重建方法的成骨效果,研究神经化与成骨的相互关系。方法26只新西兰大白兔,其中24只随机分成四组:组织工程骨组(A组),感觉神经束植入组(B组),运动神经束植入组(C组),血管束植入组(D组);另2只为空白对照组。每只动物均制备左侧股骨长1.5cm的段缺性骨与骨膜缺损,钢板固定后骨缺损处分别植入用四种方法制备的组织工程骨。植入的神经分别是隐神经和股神经肌支。术后4、8、12周摄股骨正位X线片,用放射影像学评分和X线阻射影分析比较骨缺损修复情况。结果在组织工程骨中植入感觉神经束后,比单纯组织工程骨和运动神经束植入的修复效果均有明显提高,而在组织工程骨中植入运动神经束与单纯组织工程骨修复骨缺损的效果相比较无明显差异,感觉神经束植入与血管束植入的成骨效果比较无明显差异,血管束植入组的成骨效果优于其它两组。结论利用感觉神经束植入的方法可以提高组织工程骨的成骨作用,而植入运动神经束却无此作用。  相似文献   
125.
同种异体骨与自体骨移植治疗青少年脊柱侧凸的比较研究   总被引:3,自引:1,他引:2  
[目的]观察同种异体骨移植与自体骨移植治疗青少年脊柱侧凸的临床效果.[方法]对1996~2006年本科收治的63例青少年脊柱侧凸患者的临床资料,采用回顾性"病例-对照"研究方法进行分析,A组(同种异体骨移植组)32例,10~15岁,平均12.2岁;Cobb's角38°~113°,平均62°;B组(自体髂骨移植组)31例,年龄9~14岁,平均12.4岁;Cobb's角41°~105°,平均54°.所有患者均选择中华长城椎弓根内固定系统经后路矫正,术后定期随访并对临床效果进行评估.[结果]出院后2个月即开始随访,随访时间18~24个月,平均26个月;亦无严重并发症发生;A组的手术时间、失血量较B组患者减少,组间具有统计学意义(P<0.01).[结论]两组患者具有相似的临床效果,在严格掌握适应证,充分术前准备、正确手术操作、及时术后处理的前提下,同种异体骨移植能够有效替代自体髂骨移植治疗青少年脊柱侧凸.  相似文献   
126.
OBJECTIVE: To evaluate the initial results of brachytherapy for prostate cancer with permanent iodine-125 implant in Japan. METHODS: The results obtained with brachytherapy in the initial 100 Japanese patients treated at Nagano Municipal Hospital were reviewed. Patients with a prostate-specific antigen (PSA) level of less than 10 ng/mL and a Gleason's scores of 5, 6, 3 + 4 were classified as having a low risk of recurrence. Patients with a PSA level of 10-20 ng/mL and/or a Gleason's score of 4 + 3 were classified as having an intermediate risk for recurrence. Seventy-eight of the low-risk patients and 19 of the intermediate-risk patients were treated by seed implants alone, or seed implants combined with preceding external radiation, respectively. A total of 53 patients received neoadjuvant hormone therapy. The efficacy and morbidity of brachytherapy were investigated using the serum PSA, International Prostate Symptom Score, quality of life score and uroflowmetry data. RESULTS: The average V100 and D90 obtained by post-implant dosimetry was 94.3 and 113.7%, respectively. Serum PSA decreased gradually after treatment, although it had still not reached a nadir after 1 year. There was little difference of the PSA level between the patients with and without neoadjuvant hormone therapy even at 1 year after seed implantation. There were no PSA biochemical failure or clinical recurrence during the follow-up period. Voiding symptoms worsened until 3 months after treatment, and then gradually improved. Acute urinary retention occurred transiently in one patient (1%). Rectal bleeding and severe diarrhea did not occur. CONCLUSION: Brachytherapy is a feasible and effective option for the treatment of prostate cancer in Japanese men. Brachytherapy may have a different effect in Japanese patients with respect to voiding symptoms. Urinary retention was rare, but voiding symptoms were persistent in Japanese patients. Neoadjuvant hormone therapy deserves investigation to determine whether it can achieve better results, especially in patients with an intermediate risk.  相似文献   
127.
目的探讨鼻内镜下经鼻腔直接入路行蝶窦及中颅窝手术的方法. 方法鼻内镜下经较宽大一侧鼻腔将中鼻甲向外推移,鼻腔扩张器扩大视野,直达并开放蝶窦前壁, 鼻内镜与显微镜联合切除病变. 结果 10例孤立性蝶窦炎术后症状消失.6例蝶窦囊肿、脑膜瘤均一次手术切除.32例垂体腺瘤17例全切除,12例次全切除,3例大部分切除,术后补充X刀治疗.48例术后随访6个月~3.5年,平均2.5年,蝶窦囊肿、蝶窦炎、脑膜瘤无复发,3例垂体腺瘤复发,无颅内感染并发症,无鼻腔粘连、鼻出血等鼻腔并发症. 结论鼻内镜联合显微镜经鼻腔蝶窦及中颅窝手术损伤小、出血少、手术时间短、效果好.  相似文献   
128.
双节段人工腰椎间盘置换术的疗效与探讨   总被引:1,自引:0,他引:1  
[目的]观察采用以双段SB Charite Ⅲ人工椎间盘置换术治疗退变性腰椎间盘疾病的l临床结果并探讨其可行性。[方法]自2000年10月至2006年8月,对22例L4-S1退变的病例采用双节段人工腰椎间盘置换术,男16例,女6例;年龄43~54岁,平均48岁;均获得随访,随访时间10—61个月(平均37.4个月),分别于手术前后对患者的情况进行JOA评分和影像学对比。[结果]术后病例JOA评分较术前显著提高(P〈0.05)。按FRANKLE标准,JOA评分改善率1年后优12例,良7例,可3例;3年后共获得随访18例,其中优10例,良5例,可3例。术后X线片显示人工椎间盘位置正确,椎间隙高度恢复正常,椎间活动度得到维持。15例患者返回原工作,2例变换工作,1例退休。所有病例无假体功能并发症发生,无假体松动、半脱位、下沉。[结论]在严格适应证的前提下,双节段人工椎间盘置换术是可以获得满意临床疗效的,可在有条件的医院积极开展。  相似文献   
129.
Measurement of ultrasonographic parameters provides information concerning not only bone density but also bone architecture. We investigated the usefulness of ultrasonographic parameters and bone mineral density (BMD) to evaluate the probability of Colles' fracture. Two-hundred eighty-nine postmenopausal women (62.3 +/- 8.7 yr) with (n = 76) and without (n = 213) Colles' fracture were studied. BMD of lumbar spine and proximal femur was evaluated in all women by dual-energy X-ray absorptiometry (DXA) and speed of sound (SOS), broadband ultrasound attenuation (BUA), and stiffness in the calcaneus were measured by a Sahara ultrasonometer (Hologic). Patients suffering from Colles' fracture had lower values of BMD adjusted by height at the lumbar spine, L2-L4 (0.797 g/cm2 vs 0.860 g/cm2), femoral neck (0.685 g/cm2 vs 0.712 g/cm2 ), SOS (1518 m/sg vs 1525 m/sg), and stiffness (74.6 vs 77.7) (p < 0.05). Nevertheless, BUA values were similar in both groups. After stepwise logistic regression analysis, the area found under receiver operating characteristic (ROC) curves was 0.60 for L2L4 and 0.63 for a formula combining L2L4 and height. Our data suggest that patients suffering from Colles' fracture have lower values of BMD by DXA, SOS, and stiffness. However, the ability of these techniques to discriminate is low because the values for the area under ROC curve are 0.60 for L2-L4 and 0.63 for a formula derived of the combination of L2-L4 and height.  相似文献   
130.
We tested the hypothesis that bone mineral density (BMD) and bone mineral content (BMC) in proximal human femur specimens in the upper neck region of interest (ROI) and femoral neck axis length (FNAL) provide a significantly better prediction of femoral bone strength than standard ROIs in vitro. BMD and BMC were measured in 110 proximal femur specimens using a standard dual-energy X-ray absorptiometry (DXA) scanner. The analysis included a new ROI in the upper neck as well as the standard ROIs. FNAL was obtained from the scan images. The specimens' failure-load was measured in a mechanical loading device, simulating a fall on the greater trochanter. For the standard ROIs, correlations between failure-load and BMD ranged from R2 = 0.64 (shaft ROI) to R2 = 0.70, p < 0.001 (femoral neck). Prediction of strength by BMD did not significantly differ from those of BMC (R2 ranging from 0.65 to 0.75, p < 0.001). In the upper neck ROI, for both BMD and BMC correlations with failure-load were higher (R2 = 0.76 and 0.81, respectively; p < 0.001). A lower, yet still significant, correlation was found between FNAL and bone strength (R2 = 0.23, p < 0.001). Normalization of failure-load with respect to FNAL did not significantly increase the correlations with densitometric measures. This study provides in vitro evidence indicating that among the ROIs of the proximal femur the newly defined upper neck ROI provides the best prediction of bone strength. Only a weak association was observed between failure load and FNAL.  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