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   96篇
  免费   9篇
  国内免费   5篇
  2023年   2篇
  2021年   1篇
  2020年   2篇
  2019年   3篇
  2018年   5篇
  2017年   2篇
  2016年   6篇
  2015年   6篇
  2014年   5篇
  2013年   4篇
  2012年   6篇
  2011年   8篇
  2010年   4篇
  2008年   2篇
  2006年   1篇
  2005年   2篇
  2004年   6篇
  2003年   2篇
  2002年   4篇
  2001年   1篇
  1999年   3篇
  1992年   3篇
  1991年   1篇
  1989年   1篇
  1988年   3篇
  1987年   1篇
  1986年   8篇
  1985年   1篇
  1984年   1篇
  1983年   3篇
  1981年   2篇
  1979年   1篇
  1978年   1篇
  1977年   2篇
  1974年   1篇
  1971年   1篇
  1968年   2篇
  1965年   1篇
  1959年   1篇
  1957年   1篇
排序方式: 共有110条查询结果,搜索用时 15 毫秒
1.
PGRP-S (Tag7) is an innate immunity protein involved in the antimicrobial defense systems, both in insects and in mammals. We have previously shown that Tag7 specifically interacts with several proteins, including Hsp70 and the calcium binding protein S100A4 (Mts1), providing a number of novel cellular functions. Here we show that Tag7–Mts1 complex causes chemotactic migration of lymphocytes, with NK cells being a preferred target. Cells of either innate immunity (neutrophils and monocytes) or acquired immunity (CD4+ and CD8+ lymphocytes) can produce this complex, which confirms the close connection between components of the 2 branches of immune response.  相似文献   
2.
Conflicting results using erythrocyte aminotransferase (eAST) stimulation to assess vitamin B6 nutritional status in patients with less severe B6 deficiencies are common. It has been claimed that the presence of different B6 vitamers may modify the activation of eAST by pyridoxal-5'-phosphate (PLP) leading to stimulatory or even inhibitory effects. To investigate the possible role of this phenomenon in producing inconsistent AST stimulations, aliquots of whole blood were incubated with equivalent amounts of different B6 vitamers, and the AST stimulation was correlated with the concentrations of PLP, measured by high-performance liquid chromatography. At the end of the incubation period the erythrocytes and plasma were separately analyzed. The conversion of non-PLP B6 vitamers to PLP, by the erythrocytes, was similar (approximately 70%) for all B6 vitamers used in the incubation experiments. The newly formed PLP accumulated in the erythrocytes, but the percentage activation of AST did not change significantly from the basal levels, in spite of the presence of increased levels of PLP and other B6 vitamers used for incubation. When PLP was used in the incubation studies, all of it was retained by the plasma and was associated with a marked suppression of plasma AST stimulation. To determine the degree to which plasma and erythrocyte AST was dose-dependent, plasma and haemolysates were incubated with increasing concentrations of PLP. A very significant inverse relationship was obtained in plasma between AST stimulation and PLP even at modest PLP levels, while haemolysates required incubation with much higher PLP concentrations to demonstrate the same effect. Since plasma PLP is considered to be the most reliable indicator of B6 nutritional status in man, our findings suggest that plasma percentage AST stimulation more closely reflects the B6 nutritional status than erythrocyte AST stimulation test which may reflect B6 status only in severe, longstanding B6 deficiencies. Conflicting results using erythrocyte AST stimulations may be attributed to the insensitivity of red cell AST to changes in PLP content. It is unlikely that the presence of non-PLP B6 vitamers in haemolysate may affect the percentage stimulation of aminotransferase enzymes by PLP.  相似文献   
3.
Rotavirus-associated diarrhea in a commercial rabbitry   总被引:5,自引:0,他引:5  
An epizootic of diarrheal disease occurred in a commercial specific-pathogen-free rabbitry, and was characterized by sudden onset, rapid spread, and high morbidity and mortality among sucklings. Affected rabbits rapidly became dehydrated and most died within two days of the onset of diarrhea. Eight of these rabbits were necropsied. Five had blunted and fused small intestinal villi with attenuated villous enterocytes. A rotavirus was isolated from four rabbits, and five survivors of affected litters had strong antibody responses to rotavirus.  相似文献   
4.
Postmortem examination of a captive-bred American kestrel (Falco sparverius) showed numerous white necrotic foci 1-2 mm in diameter throughout the liver and spleen. The results of light and spleen. The results of light and electron microscopic studies and experimental transmission to a captive American kestrel and a barred owl (Strix varia) suggests a herpesvirus similar to those dsecribed for owls and other falcons in the U.S. This is the first report of a naturally occurring case of inclusion body disease of falcons in the American kestrel.  相似文献   
5.
An amino acid, lethal to New Hampshire chickens (LD50, 150 mg/kg) was isolated from dried sclerotia of the fungus Sclerotium rolfsii (Sacc.). Purification of the rather unstable compound was effected on a cation exchange column by means of displacement chromatography and the amino acid was crystallised from 80% methanol. A structure was assigned to the compound on the basis of available chemical and physical data, namely 2(S),3(R)-2- amino-3-hydroxypent-4-ynoic acid. Confirmation of this structure was gained by direct and indirect synthetic procedures.  相似文献   
6.
7.
8.
9.
目的:探讨280例胃食管反流病(GERD)的分布特点及危险因素。方法:对临床诊断和胃镜确诊的280例GERD患者进行临床和风险因子相关性分析。结果:不论汉族还是维族,男性患者比例均明显高于女性;汉族患者高发年龄段早于维族患者(z=-2.939,P=0.003,);汉族和维族患者占反流性食管炎和Barrett食管比例分别为42.4%、81_3%及56.5%、18.8%,其中汉族患者Barrett食管比例较高(X2=14.358,P=0.000);肥胖、习惯性便秘、重体力活动者、饮食习惯不良在维族患者中的比例较高(P〈0.001)。结论:GERD与性别、年龄密切相关,男性多于女性,汉族患者发病年龄高峰旱于维族患者;汉族患者Barrett食管发生比例高于维族患者;肥胖、习惯性便秘、重体力活动、饮食习惯不良可能是GERD尤其是维族人群GERD的危险因素。  相似文献   
10.
In pregnant rock hyraxes isolated leucocytes metabolise both [3H]pregnenolone and [3H]progesterone while whole blood, erythrocytes and an erythrocyte/leucocyte mixture only metabolised [3H]progesterone. Plasma displayed no tendency to metabolically convert any one of these two steroids. In whole blood [3H]progesterone appears to be converted to 5alpha-pregnane-3,20-dione and a compound with chromatographic properties similar to that of 5alpha-pregnan-3alpha-ol-20-one. 5Alpha-pregnane-3,20-dione exhibited a high relative binding affinity for the uterine progesterone eceptor (94%), but 5alpha-pregnan-3alpha-ol-20-one displayed very little affinity for the same receptor (0.4%). 5Alpha-pregnane-3,20-dione may therefore aid in the maintenance of pregnancy. Corpora lutea metabolised progesterone to 17alpha-hydroxyprogesterone, a compound exhibiting no progestational function because of its low relative binding affinity for the uterine progesterone receptor (2%). Progesterone appears to be the main product of the corpus luteum. However, 5alpha-pregnane-3,20-dione circulated at concentrations approximately 8.5 times higher than progesterone, probably due to the metabolic conversion of progesterone to 5alpha-pregnane-3,20-dione by the blood. We conclude that in the hyrax progesterone, produced by the corpora lutea, enters the circulation, where it is reduced to 5alpha-pregnanes. 5Alpha-pregane-3,20-dione may then be transported to the uterus where it binds to the progesterone receptor to assist in the maintenance of pregnancy. This mechanism appears to be analogous to that of the African elephant which is phylogenetically related to the hyrax, except that in the elephant the 5alpha-reduced metabolites are produced by luteal tissue and not the blood.  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