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   363篇
  免费   42篇
  国内免费   1篇
耳鼻咽喉   2篇
儿科学   9篇
妇产科学   20篇
基础医学   66篇
口腔科学   9篇
临床医学   29篇
内科学   97篇
皮肤病学   14篇
神经病学   9篇
特种医学   57篇
外科学   18篇
综合类   11篇
预防医学   17篇
眼科学   15篇
药学   15篇
中国医学   3篇
肿瘤学   15篇
  2019年   6篇
  2016年   7篇
  2015年   7篇
  2014年   5篇
  2013年   10篇
  2012年   9篇
  2011年   5篇
  2010年   9篇
  2009年   5篇
  2008年   5篇
  2007年   7篇
  2006年   7篇
  2005年   5篇
  2004年   5篇
  2003年   6篇
  2001年   8篇
  1999年   6篇
  1998年   21篇
  1997年   17篇
  1996年   20篇
  1995年   18篇
  1994年   10篇
  1993年   17篇
  1992年   4篇
  1991年   6篇
  1990年   7篇
  1989年   12篇
  1988年   13篇
  1987年   8篇
  1986年   6篇
  1985年   6篇
  1984年   7篇
  1982年   6篇
  1981年   5篇
  1980年   8篇
  1979年   6篇
  1978年   5篇
  1977年   5篇
  1976年   6篇
  1975年   7篇
  1974年   5篇
  1973年   3篇
  1970年   5篇
  1969年   3篇
  1968年   3篇
  1965年   3篇
  1957年   6篇
  1956年   4篇
  1955年   4篇
  1954年   5篇
排序方式: 共有406条查询结果,搜索用时 31 毫秒
21.
Kidney transplant donors are not currently implicated in predicting BK polyomavirus (BKPyV) infection in kidney transplant recipients. It has been postulated, however, that BKPyV infection originates from the kidney allograft. Because BKPyV seroreactivity correlates with BKPyV replication and thus might mirror the infectious load, we investigated whether BKPyV seroreactivity of the donor predicts viremia and BKPyV‐associated nephropathy (BKPyVAN) in the recipient. In a retrospective cohort of 407 living kidney donor–recipient pairs, pretransplantation donor and recipient sera were tested for BKPyV IgG levels and correlated with the occurrence of recipient BKPyV viremia and BKPyVAN within 1 year after transplantation. Donor BKPyV IgG level was strongly associated with BKPyV viremia and BKPyVAN (p < 0.001), whereas recipient BKPyV seroreactivity showed a nonsignificant inverse trend. Pairing of high–BKPyV‐seroreactive donors with low‐seroreactive recipients resulted in a 10‐fold increased risk of BKPyV viremia (hazard ratio 10.1, 95% CI 3.5–29.0, p < 0.001). In multivariate analysis, donor BKPyV seroreactivity was the strongest pretransplantation factor associated with viremia (p < 0.001) and BKPyVAN (p = 0.007). The proportional relationship between donor BKPyV seroreactivity and recipient infection suggests that donor BKPyV seroreactivity reflects the infectious load of the kidney allograft and calls for the use of pretransplantation BKPyV serological testing of (potential) donors and recipients.  相似文献   
22.
目的:检测MCM5蛋白和PCNA在肺癌组织中的表达,探讨两者与肺癌各临床病理因素之间的关系及两者相互的联系,从而为评估肺癌的发生发展、预后及治疗提供理论依据。方法:运用免疫组织化学技术分别检测MCM5蛋白和PCNA在68例肺癌组织和20例正常组织中的表达情况,分析其与临床病理因素之间的关系及两者相互的联系。结果:MCM5表达的阳性信号位于细胞核,胞浆无着色。在正常肺组织中,MCM5的表达局限在上皮基底部的1/3至1/2的细胞,在肺癌组织中,MCM5的表达分布广泛,靠近上皮表面的细胞也可见大量表达。(1)正常肺组织和肺癌组织的MCM5的表达的差别有统计学意义(P<0.01)。(2)肺癌中MCM5表达与分化程度、淋巴结转移有显著相关性(P<0.05),与病人年龄、性别无显著相关性(P>0.05)。(3)PCNA的表达与肺癌的分化程度无显著相关性(P>0.05)。(4)在肺正常组织中,PCNA标记指数高于MCM5标记指数,两者具有显著差异性(P<0.05)。在肺癌组织中,PCNA与MCM5标记指数无显著差异性(P>0.05)。结论:(1)在肺组织中,微小染色体维持蛋白5(MCM5)是一种可靠的细胞增殖标志物。根据MCM5染色的组织结构差异和平均光密度能比较准确区分肺正常组织和癌组织。MCM5表达与肺癌的分化程度显著相关,因此MCM5表达可以提示肺癌的恶性程度,有助于临床判断病人的预后以及选择合适的治疗方法。MCM5与其他增殖标志PCNA相比是一种更好的细胞增殖标志物,是肺癌细胞的更好标志和分级指标。(2)PCNA在肺癌组织中过表达,提示PCNA的过表达与肺癌的发生发展关系密切。  相似文献   
23.
Systemic sclerosis (SSc) is an autoimmune systemic disease characterized by small vessel involvement that leads to tissue ischemia and fibroblast stimulation resulting in accumulation of collagen (fibrosis) in the skin and internal organs. Lipomembranous panniculitis is a peculiar type of fat necrosis and has been reported with clinical conditions, commonly with peripheral vascular diseases. We describe a case of a 43‐year‐old woman with SSc manifestations, who presented with black scaly skin plaques, associated with thickening of the subcutaneous fat tissue, on the lateral surface of her thighs, her calves, gluteal area and lower abdomen. Biopsy revealed lipomembranous panniculitis. Lipomembranous changes have been seen in connective tissue disorders such as lupus profundus, morphea, systemic sclerosis and panniculitis associated with dermatomyositis, but rarely in thighs, calves, gluteal area and lower abdomen. Almeida MSTM, Lima SCB, Carvalho LL, Almeida JVM, Santos LG, Rolim JRA, Rocha TE. Panniculitis–An unusual cutaneous manifestation of systemic sclerosis.  相似文献   
24.
加替沙星无菌检查方法的建立与标准操作探讨   总被引:4,自引:0,他引:4  
目的:建立加替沙星原料及制剂无菌检查法及标准操作方法。方法:按2005年版中国药典无菌检查法验证实验的有关要求,通过接种阳性代表菌株,对薄膜过滤、添加中和剂等去除加替沙星抗菌活性的实验方法和条件进行验证,逐步建立加替沙星原料及制剂无菌检查的标准操作方法。结果:在对加替沙星不同原料及制剂样品适当的处理基础上,采用薄膜过滤法,以0.1%蛋白胨水溶液作为冲洗液,约每滤筒300 mL 的冲洗量,每筒培养基中加入0.1 mol·L~(-1)硫酸锰溶液3 mL 可去除加替沙星对细菌的抑菌作用。结论:加替沙星具有较强的抑菌活性,通过适当的样品处理、薄膜过滤法和添加硫酸锰溶液作为重金属络合剂,去除加替沙星抑菌活性,可对解决喹诺酮类抗生素无菌检查问题起到较好的参考作用。  相似文献   
25.
保健食品微生物限度检查的方法学验证   总被引:3,自引:0,他引:3  
目的:确认对保健食品进行微生物限度检查时,昕采用的细菌、霉菌及酵母菌计数和控制菌检查方法是否适合于该保健食品的微生物限度检查。方法:按2005年版中国药典微生物限度检查法及方法学验证实验要求,对21种保健食品进行了方法学验证。结果:10个品种(血尔口服液、金舒通胶囊、事轻松胶囊、梦玉胶囊等)分别对金黄色葡萄球菌和枯草芽孢杆菌有明显的抑菌作用,阳性对照菌回收率均低于70%。结论:保健食品采用 GB/T4789-2003食品卫生微生物学检查法进行检查时,其检验结果可能不够科学,建议参照2005年版中国药典要求,通过方法验证实验建立合理的检验方法。  相似文献   
26.
Objective: New Zealand soils are deficient in the essential micronutrient, selenium. New Zealand infants have low selenium levels at birth and experience a further decline if fed cows milk based formula. This study examined the selenium status of infants fed with a new commercially available selenium supplemented formula.
Methodology Forty-four newborn infants, whose mothers wished to formula feed, were randomized in an open controlled trial to be fed a commercially available selenium supplemented cows milk formula (containing 17 μg Se/L) or an unsupplemented formula (containing 4.6 μg Se/L). Cord, 1 and 3 month blood samples were obtained for selenium status (plasma and red cell selenium and glutathione peroxidase) and thyroid function.
Results Mean plasma selenium and glutathione peroxidase values were significantly higher in supplemented than unsupplemented infants at 1 month (unpaired t -tests; P <0.0001 and P = 0.001 respectively) and 3 months ( P <0.0001 and P = 0.0005). Analysis within treatment groups between time points (paired t -tests) showed that selenium supplementation prevented the fall in plasma selenium from birth to 1 month seen in unsupplemented infants and was associated with a rise in levels between 1 and 3 months ( P = 0.002).
Conclusions Supplementing cows milk formula with selenium to replicate the levels found in breast milk is nutritionally sound. Feeding from a few days of age with a formula containing 17 μg Se/L in infants with low selenium status at birth is sufficient to cause a rise to 80% of adult levels at 3 months of age.  相似文献   
27.
Hecht  SS; Spratt  TE; Trushin  N 《Carcinogenesis》1997,18(9):1851-1854
4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) is an important metabolite of the tobacco-specific nitrosamine 4-(methylnitrosamino)-1- (3-pyridyl)-1-butanone (NNK). Using the chiral derivatizing agent, (R)- (+)-alpha-methylbenzyl isocyanate [(R)-(+)-MBIC], previous work has shown that the enantiomeric ratio of metabolically formed NNAL and its glucuronide derivative may be species dependent. However, the absolute configuration of such NNAL has not been previously reported. Synthetically prepared racemic NNAL was converted to diastereomeric esters by reaction with (R)-(+)- and (S)-(-)-alpha-methoxy-alpha- (trifluoromethyl)phenylacetic acid (MTPA) chloride (Mosher's reagent) and the products were characterized by 1H-NMR. Based on chemical shift data, the absolute configuration of NNAL in each diastereomeric ester was assigned. Hydrolysis of (R)-NNAL-(R)-MTPA gave (R)-NNAL. This was converted to the corresponding carbamate by reaction with (R)-(+)-alpha- MBIC and the absolute configurations of the diastereomeric carbamates formed by reaction of (R)- and (S)-NNAL with (R)-(+)-MBIC were thereby assigned. Conversion of metabolically produced NNAL to the same carbamates allowed us to assign the NNAL formed from NNK by rat liver microsomes as (R)-NNAL. The major and minor NNAL-glucuronide diastereomers found in the urine of patas monkeys and humans exposed to NNK were similarly assigned; they were formed from (R)-NNAL and (S)- NNAL, respectively.   相似文献   
28.
Fifty seven children with thoracic empyema (37 boys and 20 girls) aged less than 12 years were seen at the University of Port Harcourt Teaching Hospital between January 1989 and December 1991. Staphylococcus aureus was the most common organism isolated from the pus of these patients (36 (63%) patients). Pseudomonas aeruginosa, the next most common organism, was isolated in 10 (18%) patients. The most common symptoms at presentation were acute illness with fever and cough (51 (89%) patients). All the patients were treated with closed intercostal tube drainage and appropriate antibiotics. Decortication was resorted to in only one patient. There were two deaths and the overall survival rate was 97%.  相似文献   
29.
30.
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