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   355篇
  免费   40篇
  395篇
  2021年   3篇
  2019年   3篇
  2018年   3篇
  2017年   4篇
  2016年   3篇
  2015年   11篇
  2014年   5篇
  2013年   18篇
  2012年   16篇
  2011年   18篇
  2010年   10篇
  2009年   4篇
  2008年   12篇
  2007年   14篇
  2006年   13篇
  2005年   14篇
  2004年   10篇
  2003年   13篇
  2002年   14篇
  2001年   12篇
  2000年   10篇
  1999年   16篇
  1998年   8篇
  1997年   5篇
  1996年   4篇
  1994年   4篇
  1993年   4篇
  1992年   6篇
  1991年   8篇
  1990年   7篇
  1989年   8篇
  1988年   7篇
  1987年   3篇
  1986年   3篇
  1985年   10篇
  1984年   5篇
  1983年   4篇
  1982年   5篇
  1981年   4篇
  1978年   4篇
  1977年   3篇
  1976年   4篇
  1975年   3篇
  1972年   7篇
  1970年   3篇
  1968年   3篇
  1967年   6篇
  1966年   3篇
  1957年   3篇
  1909年   4篇
排序方式: 共有395条查询结果,搜索用时 15 毫秒
1.
2.
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   
3.
4.
Because it is relatively insoluble, the oxidant gas O3 may penetrate to small peripheral airways when it is inhaled. Increased responsiveness in large airways after O3 breathing has been associated with the presence of inflammatory cells. To determine whether O3 produces prolonged hyperresponsiveness of small airways associated with the presence of inflammatory cells, we exposed the peripheral lungs of anesthetized dogs to 1.0 ppm O3 for 2 h using a wedged bronchoscope technique. A contralateral sublobar segment was simultaneously exposed to air as a control. In the O3-exposed segments, collateral resistance (Rcs) was increased within 15 min and remained elevated approximately 150% throughout the 2-h exposure period. Fifteen hours later, the base-line Rcs of the O3-exposed sublobar segments was significantly elevated, and these segments demonstrated increased responsiveness to aerosolized acetylcholine (100 and 500 micrograms/ml). There were no differences in neutrophils, mononuclear cells, or mast cells (numbers or degree of mast cell degranulation) between O3 and air-exposed airways at 15 h. The small airways of the lung periphery thus are capable of remaining hyperresponsive hours after cessation of localized exposure to O3, but this does not appear to be dependent on the presence of inflammatory cells in the small airway wall.  相似文献   
5.
6.
Hepatic iodothyronine 5''-deiodinase. The role of selenium.   总被引:6,自引:0,他引:6       下载免费PDF全文
Selenium (Se) deficiency decreased by 8-fold the activity of type 1 iodothyronine 5'-deiodinase (ID-I) in hepatic microsomal fractions from rats. Solubilized hepatic microsomes from rats injected with 75Se-labelled Na2SeO3 4 days before killing were found by chromatography on agarose gels to contain a 75Se-containing fraction with ID-I activity. PAGE of this fraction under reducing conditions, followed by autoradiography, revealed a single 75Se-containing protein (Mr 27,400 +/- 300). This protein could also be labelled with 125I-bromoacetyl reverse tri-iodothyronine, an affinity label for ID-I. The results suggest that hepatic ID-I is a selenoprotein or has an Se-containing subunit essential for activity.  相似文献   
7.
The effect of the seaweed concentrate Kelpak on the yield of the tepary bean (Phaseolus acutifolius L.) grown under conditions of varying nutrient supply was investigated. Kelpak significantly increased the yield of plants growing at all concentrations of nutrient supply by increasing bean weight rather than bean number. Kelpak also tended to increase the N concentration of the beans. The results suggest that Kelpak did not act simply as a fertilizer, but as some kind of biostimulant.  相似文献   
8.
9.
The activity of the type II iodothyronine 5'-deiodinase enzyme in brown adipose tissue has been examined in rats-fed a selenium-deficient diet. Iodothyronine 5'-deiodinase activity was threefold lower in brown adipose tissue of deficient rats than in control animals. The activity of glutathione peroxidase, a biochemical index of selenium deficiency, was also greatly decreased in deficient animals. Cytochrome oxidase activity in brown fat was, however, unaltered by selenium deficiency. Acute exposure to cold (4 degrees C for 18 h) resulted in a substantial increase in iodothyronine 5'-deiodinase activity in brown adipose tissue of control rats, but the stimulatory effect of cold was attenuated in selenium-deficient animals. These results support the concept that the iodothyronine 5'-deiodinases are selenium-dependent enzymes, and indicate that the thermogenic response to cold may be impaired in selenium deficiency.  相似文献   
10.
Molecular Biology Reports - Treatment options for pancreatic cancer (PC) are severely limited due to late diagnosis, early metastasis and the inadequacy of chemotherapy and radiotherapy to combat...  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