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   117266篇
  免费   11054篇
  国内免费   9171篇
耳鼻咽喉   987篇
儿科学   1101篇
妇产科学   1156篇
基础医学   13927篇
口腔科学   1942篇
临床医学   15780篇
内科学   17540篇
皮肤病学   1209篇
神经病学   6245篇
特种医学   4284篇
外国民族医学   78篇
外科学   11963篇
综合类   20746篇
现状与发展   40篇
一般理论   6篇
预防医学   7938篇
眼科学   3365篇
药学   12218篇
  95篇
中国医学   7106篇
肿瘤学   9765篇
  2024年   431篇
  2023年   1984篇
  2022年   5006篇
  2021年   6386篇
  2020年   4761篇
  2019年   4044篇
  2018年   4173篇
  2017年   3713篇
  2016年   3562篇
  2015年   5452篇
  2014年   6658篇
  2013年   5858篇
  2012年   8542篇
  2011年   9428篇
  2010年   5935篇
  2009年   4681篇
  2008年   6062篇
  2007年   5995篇
  2006年   5809篇
  2005年   5877篇
  2004年   3826篇
  2003年   3497篇
  2002年   3005篇
  2001年   2665篇
  2000年   2810篇
  1999年   3000篇
  1998年   1997篇
  1997年   2016篇
  1996年   1548篇
  1995年   1471篇
  1994年   1268篇
  1993年   791篇
  1992年   987篇
  1991年   794篇
  1990年   664篇
  1989年   625篇
  1988年   520篇
  1987年   458篇
  1986年   399篇
  1985年   298篇
  1984年   136篇
  1983年   116篇
  1982年   68篇
  1981年   72篇
  1980年   47篇
  1979年   54篇
  1974年   1篇
  1965年   1篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
护士及护生对优质护理服务的认知比较   总被引:2,自引:0,他引:2  
目的 了解护士与护生对优质护理服务认识的异同,为护理管理者针对性制定护理人员培养计划并调整护生带教内容,提高临床护理水平提供参考.方法 采用护士优质护理观点问卷对某三级甲等医院108名护士及105名实习护生进行调查.结果 护士及护生均在护士的工作态度维度上得分率最高(86.15%,83.93%);护士及护生在优质护理5...  相似文献   
992.
目的 评估女性青少年特发性脊柱侧凸(adolescent idiopathic scoliosis,AIS)患者支具治疗效果及影响因素.方法 2003年7月至2009年7月,完成支具治疗或因侧凸进展而行手术治疗的女性AIS患者142例,初诊时平均年龄为(13.1±1.5)岁,平均主弯Cobb角29.6°±5.4°,平均Risser征为(2.0±1.5)级.定义侧凸畸形进展为末次随访Cobb角大于初诊6°以上或治疗期间建议行矫形手术(Cobb 角>45°),其余为非进展.根据侧凸进展或需手术治疗的比率来评估支具治疗效果.运用卡方检验和Logistic回归分析探讨影响支具治疗效果的因素.结果 平均支具治疗时间为(2.5±1.0)年.按照侧凸进展的定义,进展组为27例(19%),非进展组115例(81%);手术组病例18例(13%),因支具治疗而避免手术病例124例(87%).卡方检验发现侧凸进展组和手术组中以初诊年龄10.0~12.9岁、月经初潮未至、Risser征0~1级、初诊Cobb角>30°以及胸弯型居多.Logistic回归分析发现月经初潮未至(P=0.000)和胸弯型(P=0.012)是支具治疗后侧凸进展的独立预测因素,而初诊Cobb角>30°(P=0.022)是支具治疗期间因侧凸进展而需手术治疗的另一独立预测因素.结论 支具治疗可有效控制多数AIS患者的侧凸进展,而生长发育状态、侧凸严重程度和侧凸类型是影响支具疗效的重要因素.
Abstract:
Objective To analyze the outcomes of bracing treatment for girls with adolescent idiopathic scoliosis (AIS), and to investigate the predictive factors of the protocol. Methods This study included 142 girls with AIS who finished standardized bracing treatment from July 2003 to July 2009. These patients had a mean age of 13.1±1.5 years, a mean main curve of 29.6°±5.4°, and a mean Risser grade of 2.0±1.5 before bracing treatment. Curve progression was defined that Cobb angle was greater than 6° compared to bracing initiation or was aggravated to more than 45° (indicative for surgery). The outcomes of bracing treatment were assessed based on the ratio of curves of progression or indicative for surgery. Chi-square and Logistic regression Analyses were performed to investigate the predictive factors of bracing treatment. Results The duration of bracing treatment averaged 2.5±1.0 years. Twenty-seven girls with curve progression (19%)and 115 girls (81%) with non-progression were found. Final curve which was greater than 45° was found in 18 girls (13%) who need a correction surgery, the remaining 124 girls (87%) had completed bracing treatment and avoided surgery. Chi-square analyses revealed that curve progression were more common in younger girls with lower Risser grade, with initial larger Cobb angle and with a main thoracic curve pattern.Logistic regression analyses found that premenarchal status and a main thoracic curve pattern were the independent risk factors of curve progression despite bracing. While initial Cobb angle which was greater than 30° was the additional independent risk factor of progression requiring surgery. Conclusion Bracing treatment could effectively prevent curve progression in most girls with AIS. The degree of growth maturity, the pattern and grade of curve are the influencing factor for bracing treatment.  相似文献   
993.
目的探讨采用经鼻蝶向鞍底两侧扩大切除侵入海绵窦的垂体腺瘤的可行性。方法经单鼻孔显露蝶窦腹侧壁,蝶窦腹侧壁充分咬除,进入蝶窦,去除蝶窦黏膜和蝶窦隔,显露鞍底,鞍底开窗,放射状切开鞍底硬膜,切除鞍内肿瘤组织后,将牵开器的中心部分指向所侵入的海绵窦方向,咬骨钳咬除或磨钻磨除海绵窦腹侧骨质,显露海绵窦腹侧硬脑膜,自鞍底硬膜切开部分向外侧切开海绵窦腹侧硬脑膜,显露并切除海绵窦内部分肿瘤。结果肿瘤全部切除18例,次全切除2例。术中出现2例脑脊液漏,应用明胶海绵鞍内及蝶窦内填塞,术后无脑脊液漏。术后出现一过性动眼神经麻痹1例,术后3个月恢复正常。术后出现一过性尿崩12例,一过性电解质紊乱6例,均在1周内恢复正常。术后出院半个月后出现2例脑脊液鼻漏,行腰穿置管引流1周治愈。18例随访3~36个月,平均20个月,肿瘤无复发。结论采用经鼻蝶向鞍底两侧扩大切除侵入海绵窦的垂体腺瘤显露满意,切除彻底,无明显手术并发症。  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.
Wang  WeiBing  Li  YuanHai  Sun  AiJiao  Yu  HongPing  Dong  JingChun  Xu  Huang 《Der Anaesthesist》2017,66(12):936-943
Background

Unilateral spinal anesthesia (USpA) has been reported to potentiate spinal anaesthesia and is used in geriatric patients. The purpose of this study was to determine the median effective dose (ED50) of 0.5% hypobaric bupivacaine and 0.5% hypobaric ropivacaine USpA for geriatric patients (age ≥ 70 years) undergoing elective hip replacement surgery.

Methods

A total of 60 geriatric patients (age ≥ 70 years) undergoing elective hip replacement surgery were enrolled in this study. The patients were randomized into 2 groups to receive either intrathecal 0.5% hypobaric bupivacaine USpA (group B) or 0.5% hypobaric ropivacaine USpA (group R). Effective anesthesia was defined as a T10 sensory blockade level maintained for more than 60 min, and a Bromage score of 3 on the operation side within 10 min after injection with no additional epidural anesthetic required during surgery. The ED50 of 0.5% hypobaric bupivacaine and 0.5% hypobaric ropivacaine was calculated using the Dixon and Massey formula.

Results

No significant differences were found between the two groups in terms of demographic data. The ED50 of 0.5% hypobaric bupivacaine USpA was 4.66 mg (95% confidence interval CI 4.69–4.63 mg) mg and that of 0.5% hypobaric ropivacaine USpA was 6.43 mg (95% CI 6.47–6.39 mg) for geriatric patients undergoing hip replacement surgery.

Conclusion

We find the ED50 were lower, and the ED50 of 0.5% hypobaric bupivacaine and ropivacaine was 4.66 mg (95% CI 4.69–4.63 mg) and 6.43 mg (95% CI 6.47–6.39 mg), respectively, for USpA in geriatric patients (age ≥ 70 years) undergoing elective hip replacement surgery.

  相似文献   
996.
A major obstacle for the transplantation of neural stem cells (NSCs) into the lesioned spinal cord is their predominant astrocytic differentiation after transplantation. We took advantage of this predominant astrocytic differentiation of NSCs and expressed the paradigmatic beneficial neural cell adhesion molecule L1 in radial glial cells and reactive and nonreactive astrocytes as novel cellular vehicles to express L1 under the control of the promoter for the human glial fibrillary acidic protein (GFAP-L1 NSCs). Behavioral analysis and electrophysiological H-reflex recordings revealed that mice transplanted with GFAP-L1 NSCs showed enhanced locomotor recovery in comparison to mice injected with wild type (WT) NSCs or control mice injected with phosphate-buffered saline (PBS). This functional recovery was further accelerated in mice transplanted with L1-expressing radial glial cells that had been immunoisolated from GFAP-L1 NSCs (GFAP-L1-i cells). Morphological analysis revealed that mice grafted with GFAP-L1 NSCs exhibited increased neuronal differentiation and migration of transplanted cells, as well as increased soma size and cholinergic synaptic coverage of host motoneurons and increased numbers of endogenous catecholaminergic nerve fibers caudal to the lesion site. These findings show that L1-expressing astrocytes and radial glial cells isolated from GFAP-L1 NSC cultures represent a novel strategy for improving functional recovery after spinal cord injury, encouraging the use of the human GFAP promoter to target beneficial transgene expression in transplanted stem cells.  相似文献   
997.

Aim

To evaluate the prognostic efficacy of the 7th edition tumor–node–metastasis (TNM) classification compared with the 6th edition in gastric cancer patients.

Methods

A total of 1,503 gastric cancer patients undergoing surgical resection were staged using the 6th and 7th edition staging systems. Homogeneity, discriminatory ability, and monotonicity of gradients of the two systems were compared using linear trend χ2, likelihood ratio χ2 statistics, and Akaike information criterion (AIC) calculations.

Results

Significant differences in 5-year survival rates were observed for the T, N, and M subgroups using the 7th edition system, except for stage N2 and N3 patients in the 6th edition system. There were no significant differences in survival between IB and IIA in the 7th edition system. Patients with stage IV disease due to T4/N3 in the 6th edition system who were downstaged to stage III in the 7th edition system had significantly better survival than those who remained at stage IV. The 7th edition system had higher linear trend and likelihood ratio χ2 scores, and smaller AIC values compared with those for the 6th edition, which represented the optimum prognostic stratification.

Conclusions

Our study suggests that the 7th edition system performs better than the 6th edition in several aspects.  相似文献   
998.
目的 探讨高渗氯化钠对单肺通气患者呼吸力学参数的影响.方法 选择拟单肺通气剖胸手术患者60例,随机均分为高渗氯化钠治疗组(H组)和对照组(C组).在单肺通气30 min后经中心静脉导管输注7.5%氯化钠溶液(H组)或生理盐水(C组)2 ml/kg.观察单肺通气前(T1)、单肺通气后30 min(T2)、输注后30 min(T3)、60 min(T4)、单肺通气结束时(T5)的动态肺顺应性(Cdyn)、气道峰压(Ppeak)、气道平均压(Pmean)、动脉血氧分压(PaO2)、血清Na+浓度.结果 与T1时比较,两组患者T2时的Cdyn、PaO2明显降低,Ppeak、Pmean明显升高(P<0.05).与T2时比较,T3~Ts时H组Cdyn、PaO2逐渐升高,Ppeak、Pmean逐渐下降(P<0.05),且Cdyn、PaO2明显高于C组,Ppeak明显低于C组(P<0.05).T4、T5时H组Pmean明显低于C组(P<0.05).结论 7.5%氯化钠溶液对单肺通气患者的各呼吸力学参数有改善作用,对肺通气功能具有保护作用.  相似文献   
999.
The ability of the skeleton to adapt to mechanical stimuli diminishes with age in diaphyseal cortical bone, making bone formation difficult for adults. However, the effect of aging on adaptation in cancellous bone, tissue which is preferentially lost with age, is not well characterized. To develop a model for early post-menopausal women and determine the effect of aging on cancellous bone adaptation in the adult mouse skeleton, in vivo tibial compression was applied to adult (26 week old) osteopenic female mice using loading parameters, peak applied load and peak diaphyseal strain magnitude, that were previously found to be osteogenic in young, growing (10 week old) mice. A Load-Matched group received the same peak applied loads (corresponding to +2100 με at the medial diaphysis of the tibia) and a Strain-Matched group received the same peak diaphyseal strains (+1200 με, requiring half the load) as the young mice. The effects of mechanical loading on bone mass and architecture in adult mice were assessed using micro-computed tomography and in vivo structural stiffness measures. Adaptation occurred only in the Load-Matched group in both the metaphyseal and diaphyseal compartments. Cancellous bone mass increased 54% through trabecular thickening, and cortical area increased 41% through medullary contraction and periosteal expansion. Adult mice were able to respond to an anabolic stimulus and recover bone mass to levels seen in growing mice; however, the adaptive response was reduced relative to that in 10 week old female mice for the same applied load. Using this osteogenic loading protocol, other factors affecting pathological bone loss can be addressed using an adult osteopenic mouse model.  相似文献   
1000.
肝素标记SPIO增强MRI诊断大鼠肝癌病灶   总被引:1,自引:0,他引:1  
目的:探讨肝素标记超顺磁氧化铁粒子(HepSPIO) 对大鼠肝癌灶的增强作用。材料和方法:应用Gouys 法测定磁化率;应用二乙基亚硝胺建立大鼠化学诱导性肝癌模型;观察静注Hepspio 前后大鼠肝癌的显示情况,并与病理检查对照分析。结果:HepSPIO 的磁化率为201-5 ×10 - 3/g(25 ℃) ;4 只大鼠肝癌模型共有27 个瘤结,平均直径2-4 ±1-3m m 。增强后质子加权像癌灶检出率由平扫的33-3 % (9/27) 提高到74-1 % (20/27) ,病灶对比度/ 噪声比(CNR) 由0-7±1-9 提高至4-2 ±4-0 ;T2 加权像癌灶检出率由平扫的59-3 % (18/27) 提高到77-8 % (22/27) ,CNR 由2-8 ±2-1 上升至3-9 ±3-3 。结论:HEPSPIO 是一种新型磁共振肝网状内皮系统显影剂,对提高肝脏微小病灶的检出率有重要帮助。  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