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   141557篇
  免费   14214篇
  国内免费   9602篇
耳鼻咽喉   1083篇
儿科学   1982篇
妇产科学   1463篇
基础医学   13116篇
口腔科学   2669篇
临床医学   19805篇
内科学   16616篇
皮肤病学   1671篇
神经病学   4853篇
特种医学   4799篇
外国民族医学   44篇
外科学   11201篇
综合类   31463篇
现状与发展   42篇
一般理论   8篇
预防医学   13782篇
眼科学   3728篇
药学   16379篇
  245篇
中国医学   11348篇
肿瘤学   9076篇
  2024年   591篇
  2023年   2164篇
  2022年   5454篇
  2021年   6822篇
  2020年   5623篇
  2019年   4201篇
  2018年   4199篇
  2017年   4727篇
  2016年   3983篇
  2015年   6601篇
  2014年   8204篇
  2013年   8455篇
  2012年   12589篇
  2011年   13290篇
  2010年   10384篇
  2009年   8708篇
  2008年   9403篇
  2007年   9169篇
  2006年   8037篇
  2005年   7088篇
  2004年   4743篇
  2003年   4344篇
  2002年   3534篇
  2001年   2789篇
  2000年   2331篇
  1999年   1738篇
  1998年   995篇
  1997年   1005篇
  1996年   755篇
  1995年   641篇
  1994年   591篇
  1993年   350篇
  1992年   324篇
  1991年   308篇
  1990年   271篇
  1989年   210篇
  1988年   203篇
  1987年   182篇
  1986年   118篇
  1985年   92篇
  1984年   46篇
  1983年   43篇
  1982年   17篇
  1981年   11篇
  1980年   7篇
  1979年   14篇
  1978年   2篇
  1975年   4篇
  1974年   3篇
  1973年   5篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
目的 观察人羊膜间充质细胞(human amnion mesenchymal cells,hAMCs)体外诱导向成骨细胞分化,为骨组织工程提供种子细胞。方法 从剖宫产后废弃的人羊膜组织分离培养hAMCs,经成骨细胞诱导条件培养基诱导后,对细胞形态特征、碱性磷酸酶、骨桥素、骨钙素表达以及I型胶原分泌进行观察和检测。结果 原代培养的hAMCs形态呈长梭形或不规则形,呈均匀分布生长,传代后细胞体积略变大,约5~7d传代1次。经成骨细胞诱导培养15d后,hAMCs碱性磷酸酶、骨钙素、骨桥素的表达呈阳性,并且检测有I型胶原分泌。结论 hAMCs易于体外分离培养及扩增,体外成骨细胞定向诱导的hAMCs具有典型的成骨细胞的形态和功能性特征,是良好的骨组织工程种子细胞。  相似文献   
992.
乳腺癌是激素依赖性肿瘤,内分泌药物的选择除了根据患者的年龄、病灶部位、手术到复发的间隔时间以及受体测定等因素外,还要根据不同药物的作用机制以及副反应而定。随着对内分泌治疗药物作用机制的深入研究和大规模临床研究的证实,激素受体阳性乳腺癌的内分泌治疗疗效将不断提高。  相似文献   
993.
目的研究腘静脉肌袢代瓣术进行深静脉瓣膜重建对重度原发性下肢深静脉瓣膜功能不全(PDVI)的疗效。方法选取106例CEAP分级4级以上患者,随机分为肌袢代瓣联合浅静脉手术组和单纯浅静脉手术组,对比两组术前、术后14 d及术后2年的静脉疾病临床严重度评分(VCSS)。结果两组术后14 d VCSS总分及疼痛、静脉曲张、炎症及溃疡评分均较术前明显下降(P<0.05),但组间比较差异无统计学意义(P>0.05)。术后2年VCSS总分[(3.5±1.8)vs.(4.7±3.1),P=0.039]、静脉曲张(P=0.026)与水肿(P=0.021)评分肌袢组较单纯浅静脉组显著下降。结论对CEAP分级4级以上,且合并严重静脉水肿的PDVI患者,肌袢代瓣术联合浅静脉剥脱术远期疗效优于单纯浅静脉手术。  相似文献   
994.
目的 探讨骨髓移植诱导临床心脏移植后供者特异性免疫耐受的可行性.方法 采取供心的同时采用改良"灌流法"获取供者的骨髓350 ml,经过滤及离心处理后,加入细胞冷冻保护液共80ml,分装于低温冻存袋,经程序降温,置于-80℃冰箱中保存.在常规原位心脏移植术后40 d,取冻存骨髓快速复温,穿刺受者双侧髂后上嵴,立即行骨髓腔内骨髓细胞输注(IBM-BMT),共输注单核细胞1.2×107/kg,CD34+细胞2.38×105/kg.骨髓输注前3 d行预处理,包括应用氟达拉滨、抗胸腺细胞球蛋白及全身淋巴结照射.骨髓移植后静脉应用他克莫司(Tac),维持血Tac浓度谷值在10~20μg/L;3周后改为口服Tac+吗替麦考酚酯(MMF);6周后改为环孢素A及MMF.分别于心脏移植后2、4、8和12周采集受者外周血,分别于术后4、8和12周采集受者的骨髓,应用短串联重复序列-聚合酶链反应法检测供者嵌合体.心脏移植后每周行心肌内心电图检查,每月行心肌活检1次.术后3个月,取受者及第三者外周血单核细胞,行混合淋巴细胞反应(MLR).结果心脏移植后1、2及3个月时受者的外周血及髂骨内骨髓细胞中供者来源的细胞比例分别为26.3%、19.1%、4.8%和46.3%、24.4%、7.6%.IBM-BMT后心肌内心电图监测显示心肌阻抗及R波波幅无明显变化.术后3个月行心内膜心肌活检,未见排斥反应征象.术后3个月时行超声心动图检查,提示心脏舒张、收缩功能良好.MLR提示受者对供者特异性刺激呈现低反应性,而对第三者仍保持良好的免疫活性(P<0.01).结论 采取分期骨髓移植免疫耐受诱导方案可安全、有效地建立嵌合体,成功诱导心脏移植后供者特异性免疫耐受,但远期效果有待进一步研究.
Abstract:
Objective To investigate a new strategy of bone marrow transplantation (BMT) for donor-specific tolerance induction after heart transplantation. Methods Donor bone marrow cells (BMCs)were harvested simultaneously with donor cardiac graft using modified perfusion method (PM) ,then stored in a -80 ℃ refrigerator after filtration and centrifugation. Whole BMCs (IBM-BMT) (monocytes 1.2 ×107/kg,CD34+ cells 2.38× 105/kg) in host iliac bones were injected into the bone marrow cavity 40 days after heart transplantation. Preconditoning regimens that consisted of fludarabine, antithymoctye globin and total lymphoid irradiation were performed 3 days before BMT. Tacrolimus (Tac) was administrated intravenously after BMT or orally in conjunction with mycophenolate mofetil (MMF) 3 weeks later.Cyclosporine and MMF were orally administrated 6 weeks later. Donor chimerism was detected using short tandem repeats-polymerase chain reaction in monocytes from peripheral blood at the 2nd,4th, 8th or 12th week after BMT or BMCs at the 4th, 8th or 12th week after BMT. Intramyocardium electrocardiography examination or endomyocardial biopsy was performed weekly or monthly respectively. Mixed lymphocyte reactions (MLR) were performed 3 months after BMT. Results Donor chimerism in monocytes in peripheral blood or BMCs in iliac bones measured at the 1 st,2nd and 3rd month after BMT was 26.3%, 19.1%,4.8% ,and 46.3%, 24.4%, 7.6%, respectively. After 3-month follow-up, there was no rejection confirmed by endomyocardial biopsy or intramyocardium electrocardiography. Echocardiography revealed that the diastolic and systolic function of the cardiac graft was maintained well 3 months after BMT. MLR revealed donor-specific hyporesponsiveness while immunocompetence was preserved to third-party antigens. Conclusion These findings indicate that the two-stage BMT strategy is a safe and feasible method for the induction of donor-specific tolerance via stable mixed chimerism and needs to be further confirmed after a long-term observation.  相似文献   
995.
精囊镜检诊治顽固性血精   总被引:1,自引:0,他引:1  
目的探讨经尿道精囊镜检诊治顽固性血精的临床应用价值。方法回顾性分析我院自2008年9月以来开展经尿道精囊镜检诊治8例顽固性血精患者的临床资料,结合文献复习顽固性血精的治疗方法。年龄26~55岁,平均42岁,血精病程6~48个月,平均12个月,药物和物理治疗无效。采用7F输尿管硬镜行经尿道精囊镜检。结果 8例精囊镜检手术均成功,手术时间分别为20~75min,平均35min。精囊镜检示慢性炎症5例,精囊结石2例,射精管梗阻扩张1例。无尿道和精囊损伤等并发症。术后随访时间3~24个月,7例患者血精症状消失,1例术后9个月再发血精。结论经尿道精囊镜检操作简单,创伤小,可作为顽固性血精的有效诊治方法之一。  相似文献   
996.
目的 探讨手掌压砸伤术后"尺偏手"畸形的形成原因和治疗方法.方法 对40具手标本通过测量各指指背腱膜相对于指骨的位置、手内在肌的重量及生理横切面积,为明确临床"尺偏手"畸形的病因提供解剖学研究基础.2007年3月至2010年2月,对6例严重手压砸伤造成术后"尺偏手"畸形的患者进行手内在肌功能重建术.结果 解剖学研究发现指背腱膜及伸肌腱有将掌指关节拉向尺侧的作用力,而手内在肌则与之对抗,形成向桡侧的作用力.在正常手中,这两种作用力是平衡的;而在压砸伤术后手内在肌缺损的情况下,就失去了向桡侧的作用力,导致了临床中常见的"尺偏手"畸形.6例"尺偏手"畸形手内在肌功能重建术后随访时间平均8.5个月,尺偏得到较好的纠正,拇对指功能得到明显改善.结论 严重手掌压砸伤术后因手内在肌缺损导致肌力失衡引起"尺偏手"畸形,应在急诊手术中尽量保留手内在肌的连续性并修复断裂的手内在肌;对已经形成的"尺偏手"畸形,需行手内在肌重建术.
Abstract:
Objective To investigate the cause and management of ulnar club-hand secondary to crush injury of the palm. Methods Forty eadaver hands were dissected to measure the relative position between extensor aponeurosis and phalanges, the weight and cross-sectional area of intrinsic muscles to provide anatomical basis of the causes of ulnar club-hand. From March 2007 to February 2010, six patients with ulnar club-hand secondary to severe crush injury underwent intrinsic muscle reconstruction. The causes of ulnar club-hand were investigated in these cases. Results Anatomical dissection revealed that the extensor aponeurosis and extensor tendon of the finger tend to deviate the metacarpophalangeal joint ulnarly, while the intrinsic muscles work antagonistically to pull the joint radially. In the normal hand, these two kinds of acting forces are balanced. In the absence of intrinsic muscles after severe crush injury of the hand, this balance is broken, and the hand tends to deviate ulnarly. Intrinsic muscle reconstruction in six patients with ulnar club-hand secondary to palm crush injury restored the balance and corrected the ulnar deviation deformity after 8.5 months follow-up. Thumb opposition was also improved. Conclusion The absence of hand intrinsic muscles was the main cause of ulnar club-hand in severe crush injury. In the emergency operation, ruptured intrinsic muscles should be repaired whenever possible to prevent ulnar club-hand. For established ulnar club-hand, intrinsic muscle reconstruction should be done to correct the deformity.  相似文献   
997.
目的呼吸道非结核分枝杆菌定植是HIV感染者发生播散性非结核分枝杆菌感染的危险因素,并可能对肺结核的诊断造成干扰。我国HIV感染者中非结核分枝杆菌呼吸道定植情况和临床特点目前尚无较大样本的研究报道。本文分析HIV感染者痰培养中非结核分枝杆菌的阳性率和相关因素,从而总结其临床特点。方法 2006年8月至2008年7月,对广西省4个诊疗机构中CD4〈350的HIV感染者进行临床症状、胸片、痰涂片,痰分枝杆菌培养和血液分枝杆菌培养在内的结核筛查。结果 1073例HIV感染者在结核筛查时进行了痰分枝杆菌培养,检出非结核分枝杆菌87例(8.1%),129例(12.0%)为结核分枝杆菌。在痰培养阳性的标本中,43%为非结核分枝杆菌。非结核分枝杆菌在呼吸道的定植率随着患者CD4水平降低而逐渐升高,在CD4计数〉200/μl、100~200/μl、50~100/μl和〈50/μl的患者组中分别为2.8%、6.4%、7.1%和9.8%。痰涂片抗酸杆菌阳性的患者中12.0%为非结核分枝杆菌,非结核分枝杆菌呼吸道定植的患者中8.5%痰涂片结果为抗酸杆菌阳性。与痰培养阴性的患者相比,有呼吸道非结核分枝杆菌定植的患者CD4水平较低,除体重下降更多见外,其他临床症状如发热、咳嗽、盗汗、乏力等,以及胸片异常表现均未增加。结论我国HIV感染者中痰培养非结核分枝杆菌的阳性率较高,尤其是在CD4〈200的患者中,需要加强临床观察。在未有进行细菌培养的情况下,非结核分枝杆菌在呼吸道的定植可能造成结核的误诊,应给予重视。  相似文献   
998.
目的探讨RNA干扰靶向抑制磷脂酰肌醇3-激酶(P13K)P85α蛋白表达对结直肠癌细胞周期与细胞凋亡的影响。方法设计4条shRNA干扰载体及1条阴性对照载体.分别稳定转染结直肠癌SW480细胞。采用Western blot筛选出对P13K P85α蛋白抑制效率最高的shRNA干扰片段.然后通过PI标记法和Annexin V—FITC标记法分别检测干扰后SW480细胞周期和细胞凋亡情况。结果转染shRNA/324后.SW480细胞P13K P85α蛋白降低最为显著.抑制率为90%。选择该干扰片段进行后续实验。干扰组与对照组SW480细胞的G1期细胞数量分别占(62.4±2.7)%和(51.2±3.5)%;S期细胞数量占(23.9±1.7)%和(34.1±3.4)%;氟尿嘧啶所诱导的细胞凋亡率为(11.1±3.7)%和(1.4±0.6)%;上述差异均有统计学意义(P〈0.05)。结论P13K P85α蛋白表达下降可引起结直肠癌SW480细胞周期阻滞,细胞凋亡增加:PI3K P85α可能成为结直肠癌基因治疗的新靶点。  相似文献   
999.
Primary adenocarcinoma of the renal pelvis is rarely reported in the literature. Here we present a case of primary mucinous adenocarcinoma of the renal pelvis with elevated serum carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) levels. A 56-year-old woman was referred to our center with intermittent fever and left-sided back pain for 1 month. Computed tomography showed bilateral nephrolithiasis, mild right hydronephrosis and left pyonephrosis accompanied with ambiguous soft tissues. A radionucleorenogram showed that the glomerular filtration rate of the left and right kidney was 0 and 79 ml/min, respectively. Left nephrectomy was performed without lymph node dissection. Histopathology revealed mucinous adenocarcinoma and elevated serum CEA and CA19-9 levels were found. She died of multiorgan metastasis after 5 months. A review of the literature is also reported.  相似文献   
1000.
Seroma has long been listed as a complication of MammoSite brachytherapy. Palpable abnormalities are clinically apparent months after treatment and a vast majority of patients demonstrate seroma formation in radiologic studies. We embarked on this study to evaluate the actual sonographic incidence and eventual sonographic resolution, possible contributing factors, cosmesis, pain, and local control associated with seroma formation after MammoSite partial breast irradiation (PBI). We investigated 160 patients who underwent MammoSite PBI from 2002 to 2006 of whom 100 patients had serial sonographic information. Clinical and tumor variables, infection, pain, and cosmesis were investigated. Dosimetric data including volume of balloon, dose at balloon surface, and at skin were analyzed. After a median follow-up of 36 months, the incidence of sonographically confirmed post-radiation seroma was 78% within the first 1 year following radiation and steadily decreased with time. The average size of a seroma cavity was 2.3 cm (range 0.6-6 cm) with a decline to an average of 1.4 cm after 1 year, with complete resolution in 65% of patients at 2 years. No statistically significant correlation was found between patient characteristics, tumor variables, and volumetric or dosimetric data for seroma formation. Excellent/good cosmetic scores were achieved in 94% of women with and 92% without seroma. Local control was equivalent between patients with and without seroma. Consecutive sonographic imaging reveals a high rate of seroma formation after MammoSite PBI, with resolution in 65% of patients by 2 years without intervention. Seroma formation does not prevent an excellent cosmetic result or alter local control.  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