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   285篇
  免费   10篇
  国内免费   18篇
耳鼻咽喉   2篇
儿科学   12篇
妇产科学   47篇
基础医学   37篇
口腔科学   3篇
临床医学   45篇
内科学   64篇
皮肤病学   1篇
神经病学   6篇
特种医学   34篇
外科学   16篇
综合类   16篇
预防医学   8篇
药学   12篇
肿瘤学   10篇
  2022年   1篇
  2021年   3篇
  2019年   2篇
  2018年   2篇
  2017年   3篇
  2016年   3篇
  2015年   4篇
  2014年   8篇
  2013年   7篇
  2012年   4篇
  2011年   5篇
  2010年   13篇
  2009年   10篇
  2008年   8篇
  2007年   26篇
  2006年   9篇
  2005年   9篇
  2004年   6篇
  2003年   9篇
  2002年   9篇
  2001年   8篇
  2000年   8篇
  1999年   6篇
  1998年   16篇
  1997年   16篇
  1996年   17篇
  1995年   10篇
  1994年   19篇
  1993年   4篇
  1992年   1篇
  1991年   4篇
  1990年   8篇
  1989年   15篇
  1988年   7篇
  1987年   4篇
  1986年   4篇
  1985年   5篇
  1984年   3篇
  1983年   3篇
  1982年   1篇
  1981年   5篇
  1980年   5篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
排序方式: 共有313条查询结果,搜索用时 296 毫秒
1.
BACKGROUND: Developments in accelerator mass spectrometry (AMS) now permit the determination of femtogram amounts of 26Al in blood and in various tissues with good precision and free of external contamination. METHODS: In the present study we used trace quantities of 26Al to investigate the intestinal absorption and compartmentalization of aluminium in rats with renal failure (Nx, 5/6 nephrectomy) and in pair- fed controls (C). Single oral doses of 20 ng 26Al were administered to six animals in each group and, subsequently, 24-h post-load 26Al was analysed in serum, urine, bone, liver, and spleen by means of AMS. RESULTS: Serum concentrations of 26Al were significantly lower in uraemic rats compared to controls, whereas urinary excretion was comparable (Nx, 7.11 +/- 5.78 pg/day vs C, 9.46 +/- 6.10 pg/day), suggesting a higher fraction of ultrafiltrable serum 26Al in uraemia. The target tissues of cellular transferrin-mediated 26Al uptake, liver and spleen, tended to show a larger degree of aluminium accumulation in controls (0.26 +/- 0.31 pg/g vs Nx, 0.14 +/- 0.10 pg/g and 0.37 +/- 0.27 pg/g vs Nx, 0.25 +/- 0.27 pg/g respectively). In contrast, in bone, a site of extracellular aluminium deposition, 26Al concentrations were more elevated in uraemia (1.22 +/- 0.59 pg/g vs C: 0.68 +/- 0.30 pg/g). Estimated total 26Al accumulation in all measured target tissues was significantly higher in uraemic rats (28.15 +/- 9.90 pg vs C: 17.03 +/- 7.03 pg) and total recovery of 26Al from tissue and urine was 26.58 +/- 6.74 pg in controls and 35.75 +/- 7.03 pg in uraemic animals, suggesting a fractional absorption of 0.133% and 0.175% respectively. CONCLUSIONS: Our data suggest that fractional absorption from a dietary level dose of 26Al is about 0.13%. Compartmentalization occurs in transferrin-dependent target tissues such as liver and spleen; however, in quantitative terms extracellular deposition in bone is more important. Uraemia has a significant effect on the intestinal absorption and compartmentalization of aluminium. It enhances fractional absorption and increases subsequent extracellular deposition of aluminium in bone. However, at the same time uraemia does not increase transferrin-dependent cellular accumulation of aluminium in liver and spleen.   相似文献   
2.
The combination of high-dose busulfan (16 mg/kg) and 200 mg/kg cyclophosphamide is gaining increasing significance as a preparative regimen prior to autologous, syngeneic, or allogeneic marrow transplantation. A new regimen of high-dose busulfan in conjunction with a reduced dose of 120 mg/kg cyclophosphamide has recently been described as a preparative regimen prior to allogeneic transplantation. To determine the drug-related nonhematologic toxic effects of this new regimen without confounding factors associated with allogeneic transplantation, we conducted a pilot study using this new regimen in 20 patients with acute myeloid leukemia (AML) in first remission prior to autologous unpurged marrow transplantation. All patients experienced transient non-life-threatening acute drug-related toxicity with skin reactions in 20 (100%), nausea and vomiting in 20 (100%), oral mucositis in 18 (90%), hepatic functional impairment in 17 (85%), hemorrhagic cystitis in three (15%), and generalized seizures in two (10%) of these patients, respectively. Two procedural, fatal complications resulted from infectious causes that were not directly related to the speed of hematopoietic reconstitution or the toxicity of the preparative regimen. The 3-year event-free survival estimate (55% +/- 11%) and probability of leukemic recurrence (38% +/- 11%) attained with this new regimen in recipients of autografts in first remission of AML are promising and challenge comparisons with preparative regimens employing combinations of cytotoxic agents or total body irradiation (TBI).  相似文献   
3.
4.
牛津膝置换是使用最广泛的膝关节单髁置换(UKR)。牛津膝在37年前开始应用,拥有一个全匹配的活动衬垫,因而磨损率非常低。牛津膝最主要的使用指征是膝关节前内侧骨关节炎,这种病人至少占所有需要行膝关节置换术患者的50%。由于这一系统的设计特点,传统UKR的反指征,如年龄、活动量、肥胖、髌股关节损害和软骨钙质沉着症等对于牛津膝均不是反指征。与全膝关节置换(TKR)相比,牛津膝提供更快的康复、更好的功能、更大的活动度和更好的术后满意度,发生并发症更少、程度更轻,病残率和死亡率更低。一个持续超过30年的研究显示在90%的病例中,牛津膝为患者终生提供了优或良的临床结果,且不需要翻修。在最近15年,牛津膝通过微创手术入路植入,涉及6000多例使用该入路牛津膝置换的9个研究报道显示,10年生存率约95%。在许多这样的研究中,医生们在拟行膝关节置换的患者中约50%使用了牛津单髁膝置换。  相似文献   
5.
目的:制备大鼠在体缺血再灌注模型,观察缺血预处理程序中心肌环磷酸腺苷含量及环磷酸腺苷依赖蛋白激酶活性的变化。方法:实验于2005-03/2006-10在解放军沈阳军区总医院医学实验动物中心和全军心血管研究所实验室完成。实验分组:选用健康雌性SD大鼠36只,根据预适应程序分为第1,2,3次缺血,第1,2,3次再灌注,每一时间点6只大鼠。实验过程:用手术套管法造成左冠状动脉主干缺血及再灌注。所有实验动物在实验程序结束后,取出心脏迅速置液氮保存备用。实验评估:用放射免疫法测环磷酸腺苷水平,生化法测环磷酸腺苷依赖蛋白激酶活性变化。结果:36只大鼠均进入结果分析。①环磷酸腺苷含量:第1次再灌注组低于第1次缺血组[(0.325±0.015),(0.395±0.024)pmol/g,t=6.06,P<0.001],第2次再灌注组低于第2次缺血组[(0.523±0.017),(0.708±0.067)pmol/g,t=6.56,P<0.001],第3次再灌注组低于第3次缺血组[(0.567±0.031),(0.712±0.038)pmol/g,t=7.24,P<0.001]。②环磷酸腺苷依赖蛋白激酶活性:第1次再灌注组低于第1次缺血组[(10.115±1.000),(16.351±0.849)pkat/g,t=11.12,P<0.001],第2次再灌注组低于第2次缺血组[(11.877±2.213),(14.869±0.619)pkat/g,t=3.31,P<0.01],第3次再灌注组低于第3次缺血组[(11.745±0.987),(14.766±0.329)pkat/g,t=7.09,P<0.001]。③缺血预处理程序中心肌环磷酸腺苷含量及环磷酸腺苷依赖蛋白激酶活性随缺血及再灌注呈周期性波动。在5min缺血预处理时表现为明显增高,而在间隔的再灌注程序中恰呈相反改变,有明显下降的趋势。结论:环磷酸腺苷及环磷酸腺苷依赖蛋白激酶的周期性波动变化可能是激发心肌缺血预处理的机制之一,环磷酸腺苷可能在预处理保护作用中起一些作用。  相似文献   
6.
7.
A prototype ultrafast cine computed tomographic (CT) scanner, designed specifically for cardiac imaging, was used to evaluate a preliminary series of patients with prior myocardial infarction (n = 21) and a control group without coronary artery disease (n = 5). Multilevel 50-msec CT scan exposures were obtained during peripheral intravenous bolus injections of contrast medium. A comparison was made between cine-CT scans and standard left ventriculographic images in assessing segmental left ventricular motion. Results indicate that cine CT, performed at sufficiently rapid speeds (20 scans per second) to allow useful analysis of regional ventricular wall motion, can provide adequate image quality. Analysis of 110 segments revealed a good correlation (90.9%) between the two techniques in characterizing normal from abnormal regional wall motion. Cine CT, based on this initial study, demonstrates considerable potential for evaluating not only cardiac chamber dimensions but also segmental wall dynamics.  相似文献   
8.
BACKGROUND: The study aim was to analyse the results of randomized controlled trials (RCTs) comparing recombinant FSH and urinary-derived FSH gonadotrophins [hMG, urinary purified FSH (FSH-P) and highly purified FSH (FSH-HP)] in an IVF/ICSI programme. METHODS: All published truly RCTs using a long protocol of GnRH agonists for down-regulation, were reviewed. Data of pregnancy rate per started cycle were extracted, and odds ratios (OR) calculated using a fixed effect model. Subgroup analysis was carried out to compare recombinant FSH (rFSH) with each product (hMG alone, FSH-P alone and FSH-HP alone). RESULTS: There was no statistically significant difference in the pregnancy rate per started cycle between rFSH and urinary-derived FSH gonadotrophins (OR 1.07; 95% CI 0.94-1.22). Subgroup analysis showed no statistically significant difference in the pregnancy rate per started cycle between rFSH versus hMG (OR 0.81; 95% CI 0.63-1.05), rFSH versus FSH-P (OR 1.24; 95% CI 0.98-1.58) and rFSH versus FSH-HP (OR 1.14; 95% CI 0.94-1.40). There was no significant heterogeneity of treatment effect across the trials. CONCLUSIONS: There is no evidence of clinical superiority in clinical pregnancy rate for rFSH over different urinary-derived FSH gonadotrophins. Additional factors should be considered when choosing a gonadotrophin regimen, including the cost, patient acceptability, safety and drug availability.  相似文献   
9.
OBJECTIVE: This study was undertaken to evaluate the outcome of in vitro fertilization (IVF) in patients with advanced pelvic endometriosis and previous surgical treatment. STUDY DESIGN: A case controlled study was performed. RESULTS: Patients with the diagnosis of stage IV endometriosis with previous surgical treatment were treated by IVF (group A = 85). An age-matched group of patients (group B = 177) with tubal factor infertility were treated with the same protocol of IVF. In group A, cycle cancellation because of poor response occurred in 29.7% compared with 1.1% in the control group (relative risk 26.03, 95% CI 6.02-112.45). There were 13 (15.3%) clinical pregnancies per stimulated cycle in group A compared with 93 (52.5%) clinical pregnancies in the control group, P <.0001 (odds ratio 0.29, 95% CI 0.15-0.55). CONCLUSION: The outcome of IVF in stage IV endometriosis with previous surgery was significantly lower compared with an age-matched group of tubal factor infertility.  相似文献   
10.
OBJECTIVE: In compare the use of purified follicle-stimulating hormone with that of a preparation containing follicle-stimulating hormone and luteinizing hormone in infertile females undergoing IVF. DESIGN: Open-labelled prospective controlled single-center study. SETTING: Nile Badrawy IVF unit. PARTICIPANTS: 153 infertile females undergoing their first cycle of IVF divided into 2 groups. Interventions: Ovarian stimulation was done with either highly purified FSH for group 1 (n = 75) or human menopausal gonadotrophin group 2 (n = 78) after pituitary desensitization commenced in the midluteal phase of the preceding cycle. Monitoring was performed by ultrasound transvaginal oocyte retrieval followed by IVF and transfer of three embryos. OUTCOMES: Number of oocytes >18 mm at day of hCG, fertilization rate, embryo transfer rate, clinical pregnancy rate and incidence of ovarian hyperstimulation syndrome. RESULTS: The response to ovarian hyperstimulation was similar in both groups. The number of follicles >18 mm achieved at day of hCG was 12.3 +/- 0.9 (mean +/- SEM) following stimulation with 38.3 +/- 0.9 ampoules of Fostimon The Menogon-treated group needed 39.1 +/- 0.8 ampoules to produce 11.6 +/- 0.7 follicles. Fertilization rate (2PN/cell) was 58.6 vs. 64.2% in the Fostimon and Menogon group, respectively (p > 0.05). The number of embryos transferred per woman was 3.1 +/- 0.1 in the Fostimon group and 3.6 +/- 0.1 in the Menogon group. The pregnancy rate per woman was 33.3 vs. 25.6% in the Fostimon- and Menogon-treated groups, respectively (p > 0.05). Miscarriage rate was 16 vs 20%, respectively. However, the incidence of multiple pregnancies was significantly higher in the Fostimon-treated group (32%) vs. 10% only in the Menogon-treated group (p < 0.01). CONCLUSION: Purified FSH yields similar clinical outcome to hMG in terms of oocytes retrieved and clinical pregnancies in a standard IVF regimen.  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