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   232篇
  免费   6篇
儿科学   51篇
基础医学   12篇
口腔科学   1篇
临床医学   20篇
内科学   45篇
皮肤病学   5篇
神经病学   20篇
外科学   47篇
预防医学   3篇
眼科学   1篇
药学   20篇
肿瘤学   13篇
  2016年   4篇
  2015年   3篇
  2014年   2篇
  2013年   1篇
  2012年   1篇
  2011年   1篇
  2010年   2篇
  2008年   1篇
  2007年   5篇
  2006年   13篇
  2005年   9篇
  2004年   15篇
  2003年   9篇
  2002年   5篇
  2001年   4篇
  2000年   2篇
  1999年   13篇
  1998年   23篇
  1997年   19篇
  1996年   17篇
  1995年   18篇
  1994年   12篇
  1993年   13篇
  1992年   6篇
  1990年   5篇
  1989年   3篇
  1988年   2篇
  1986年   4篇
  1985年   3篇
  1984年   4篇
  1983年   2篇
  1981年   3篇
  1980年   1篇
  1979年   6篇
  1978年   1篇
  1977年   2篇
  1976年   1篇
  1973年   1篇
  1972年   1篇
  1971年   1篇
排序方式: 共有238条查询结果,搜索用时 15 毫秒
231.
Seasonal variations of total blood histamine were examined in twenty patients with seasonal allergic rhinitis (Japanese cedar pollinosis). In blood specimens taken in the pollen season of 1978, the symptom-free season of 1978. and the pollen season of 1979, the mean values of blood histamine were 61.6, 50.0 and 84.2 ng/ml respectively. The differences in blood histamine levels between the pollen season of 1978 and the symptom-free season of 1978 and between the symptom-free season of 1978 and the pollen season of 1979 were statistically significant. In the symptom-free season of 1978, the blood histamine levels of twenty normal subjects were also examined: the mean value was 58.2 ng/ml. The blood histamine levels of the patients in the symptom-free season were not statistically different from those of the normal subjects.  相似文献   
232.
A gradual increase in serum alpha-fetoprotein (AFP) had beenobserved in a patient with liver cirrhosis and the complicationof rectal carcinoma was disclosed 18 months later. The concentrationof serum AFP decreased rapidly after removal of the tumor andreached a normal value within a month. The level of serum AFP has remained normal and the patient hasbeen well since the operation. There has been no clinical evidenceof the existence of a liver tumor and the production of AFPby the rectal carcinoma cells was suggested.  相似文献   
233.
ABSTRACT: T-lineage cells in human decidua of early pregnancies were tested for surface markers, proliferative response, interleukin-2 (IL-2) production, and natural killer (NK) activity. T-lineage (CD2+) cells that were obtained from decidua by the use of E-rosette formation contained fewer CD3+ mature T cells and CD4+ cells than those from the peripheral blood of the same donors, while no differences were seen in the frequencies of CD8+ cells. P55 molecules of IL-2 receptor (IL-2R/p55, Tac antigen) were hardly detected on fresh decidual T-lineage cells, though approximately 20% were positive for HLA-DR. More than a half of decidual T-lineage cells expressed CD56 molecules on their surface and killed K562 cells, the prototype target of NK cells, while most of them were negative for CD16 and CD57. Upon stimulation with IL-2, decidual T-lineage cells demonstrated dose-dependent proliferative response. In addition, they were induced to produce high amounts of IL-2 by stimulation with mitogens but not with alloantigens. These results suggest that human decidua contains high numbers of CD2+3-CD16+56+ lymphocytes and that this population responds to IL-2, produces IL-2 and mediates NK activity.  相似文献   
234.
CASE REPORT: Primary hepatic lymphoma associated with chronic liver disease   总被引:7,自引:0,他引:7  
We report on a case of primary hepatic lymphoma that developed in a patient with chronic hepatitis C. Given that Japan is an area endemic for both hepatitis B and C viruses, we reviewed 51 Japanese cases of primary hepatic lymphoma, addressing the question as to whether the Japanese cases have unique characteristics and whether there is a causal relationship to the presence of chronic liver disease. Primary hepatic lymphoma most commonly affected middle-aged males. Presenting symptoms and physical findings were non-specific. Aminotransferases tended to stay in the low range compared with marked increases in lactate dehydrogenase. Sixteen patients (31%) had chronic liver disease, eight had liver cirrhosis and eight had chronic hepatitis, suggesting that there is a possible aetiological link between chronic liver disease and primary hepatic lymphoma.  相似文献   
235.
A plasma pool from 12 asymptomatic carriers seropositive for antibody against hepatitis B e antigen (anti-HBe) contained hepatitis B virus (HBV) with chimpanzee infectious doses of 1-100/mL, and another pool from 12 carriers positive for hepatitis B e antigen (HBeAg) contained 10(8)/mL doses or more. The HBeAg-positive pool contained 10(6)-fold more HBV DNA than the anti-HBe-positive pool, reflecting the difference in infectivity in chimpanzees. The precore region sequences of HBV DNA in the two plasma pools were amplified by polymerase chain reaction, and separate HBV DNA clones were propagated for determining the nucleotide sequence. Of 114 clones from the anti-HBe-positive pool, 113 displayed a point mutation from guanine to adenine at nucleotide 83 in the precore region, which converted codon 28 for tryptophan (TGG) to a stop codon (TAG), and the remaining clone had a point mutation from adenine to cytosine at the first letter of codon 1 (CTG) to inhibit the translation initiation of the precore region. Precore region defects, in contrast, were observed in only 10 (8%) of 119 clones from the HBeAg-positive pool. These results indicate the infectious capacity of HBV mutants, defective in the precore region and incapable of directing the synthesis and secretion of HBeAg, which prevail in the circulation of hosts after they seroconvert from HBeAg to anti-HBe.  相似文献   
236.
INTRODUCTION: It is known that high-strength shock disrupts the lipid matrix of the myocardial cell membrane and forms reversible aqueous pores across the membrane. This process is known as "electroporation." However, it remains unclear whether electroporation contributes to the mechanism of ventricular defibrillation. The aim of this computer simulation study was to examine the possible role of electroporation in the success of defibrillation shock. METHODS AND RESULTS: Using a modified Luo-Rudy-1 model, we simulated two-dimensional myocardial tissue with a homogeneous bidomain nature and unequal anisotropy ratios. Spiral waves were induced by the S1-S2 method. Next, monophasic defibrillation shocks were delivered externally via two line electrodes. For nonelectroporating tissue, termination of ongoing fibrillation succeeded; however, new spiral waves were initiated, even with high-strength shock (24 V/cm). For electroporating tissue, high-strength shock (24 V/cm) was sufficient to extinguish ongoing fibrillation and did not initiate any new spiral waves. Weak shock (16 to 20 V/cm) also extinguished ongoing fibrillation; however, in contrast to the high-strength shock, new spiral waves were initiated. Success in defibrillation depended on the occurrence of electroporation-mediated anodal-break excitation from the physical anode and the virtual anode. Some excitation wavefronts following electrical shock used a deexcited area with recovered excitability as a pass-through point; therefore, electroporation-mediated anodal-break excitation is necessary to block out the pass-through point, resulting in successful defibrillation. CONCLUSION: The electroporation-mediated anodal-break excitation mechanism may play an important role in electrical defibrillation.  相似文献   
237.
This article describes the case of a 71 -year-old woman in whom a permanent pacemaker implantation was performed through an iliac vein because of superior vena cava obstruction after aortic valve reoperation. During a 6-month follow-up, the patient did well and the pacemaker performance was satisfactory.  相似文献   
238.
BACKGROUND: Central catecholamines, particularly dopaminergic and noradrenergic systems, have affected the appetitive behavior in patients with anorexia nervosa (AN). The purpose of this study is to distinguish the characteristics of contingent negative variation (CNV) and postimperative negative variation (PINV), which may reflect the level of catecholamine in children with AN. METHODS: Eight children with AN aged 10 to 15 years and 23 age-matched healthy children were recruited. Contingent negative variation was recorded from the frontal midline (Fz), central midline (Cz) and parietal midline (Pz) referenced to linked earlobes during 30 trials consisting of a warning stimulus and an imperative stimulus with an interstimulus interval of 2 s and an intertrial interval of 10 s. The imperative stimulus of each trial required a button press. RESULTS: Children with AN had a diminished amplitude of the CNV. They had a significantly more attenuated early CNV and late CNV amplitude at Cz than normal children. No significant differences were observed between AN children and normal children in the amplitude of PINV at all three electrode sites. No difference could be found between the two groups in the frequencies of normal and abnormal duration of PINV. CONCLUSION: These findings suggest that early CNV may be diminished by norepinephrine deficiency and late CNV may be attenuated by dopaminergic deficiency in children with AN. Reduced CNV may represent impaired cognitive processes which reflect impaired appetitive behavior in AN children.  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