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   168篇
  免费   16篇
  2022年   1篇
  2020年   1篇
  2019年   1篇
  2018年   1篇
  2017年   3篇
  2015年   10篇
  2014年   7篇
  2013年   10篇
  2012年   9篇
  2011年   8篇
  2010年   13篇
  2009年   6篇
  2008年   6篇
  2007年   6篇
  2006年   3篇
  2005年   8篇
  2004年   2篇
  2003年   7篇
  2002年   3篇
  2001年   5篇
  2000年   5篇
  1999年   7篇
  1998年   7篇
  1997年   3篇
  1995年   2篇
  1994年   2篇
  1993年   8篇
  1992年   9篇
  1991年   2篇
  1990年   3篇
  1989年   1篇
  1988年   2篇
  1987年   3篇
  1986年   2篇
  1985年   3篇
  1982年   1篇
  1980年   1篇
  1979年   3篇
  1977年   2篇
  1975年   1篇
  1972年   1篇
  1961年   1篇
  1958年   1篇
  1936年   1篇
  1913年   1篇
  1911年   2篇
排序方式: 共有184条查询结果,搜索用时 328 毫秒
171.
In an effort to manage the existing population of the endangered Florida manatee (Trichechus manatus latirostris), as many individuals as possible are rehabilitated from illness or injury and released back into the waters of the state of Florida. It is not uncommon, however, for manatees recaptured for health assessment following release from rehabilitation to have elevated concentrations of serum creatinine. Although such elevated levels would be indicative of kidney failure in most other mammals, problems associated with renal function have not been evident in these recaptured manatees. To determine the possible cause(s) of the serum creatinine increase, two captive Florida manatees were manipulated to simulate many of the environmental and physical changes that occur during and shortly after release. Routine chemical analyses of serum and urine, complete blood counts, serum cortisol concentrations, and lymphocyte proliferation responses were measured. Serum creatinine concentrations increased significantly in response to decreased food intake and changes in food type. The increases differed depending on the salinity of the water in which the animals were maintained. It was found that significant changes in urinary creatinine and serum creatine kinase occurred as well, but serum cortisol concentrations were elevated only during simulated transport. Lymphocyte proliferation assays indicated that immune function was potentially impaired by extreme levels of dietary restriction and by changes in salinity. These results suggest that serum creatinine elevations and subsequent effects on the immune system might be minimized by adapting manatees undergoing rehabilitation to the diet and salinity they would encounter following release. Zoo Biol 22:103–120, 2003. © 2003 Wiley‐Liss, Inc.  相似文献   
172.

Key message

This work reports the effects of the genetic makeup, the environment and the genotype by environment interactions for node addition rate in an RIL population of common bean. This information was used to build a predictive model for node addition rate.

Abstract

To select a plant genotype that will thrive in targeted environments it is critical to understand the genotype by environment interaction (GEI). In this study, multi-environment QTL analysis was used to characterize node addition rate (NAR, node day??1) on the main stem of the common bean (Phaseolus vulgaris L). This analysis was carried out with field data of 171 recombinant inbred lines that were grown at five sites (Florida, Puerto Rico, 2 sites in Colombia, and North Dakota). Four QTLs (Nar1, Nar2, Nar3 and Nar4) were identified, one of which had significant QTL by environment interactions (QEI), that is, Nar2 with temperature. Temperature was identified as the main environmental factor affecting NAR while day length and solar radiation played a minor role. Integration of sites as covariates into a QTL mixed site-effect model, and further replacing the site component with explanatory environmental covariates (i.e., temperature, day length and solar radiation) yielded a model that explained 73% of the phenotypic variation for NAR with root mean square error of 16.25% of the mean. The QTL consistency and stability was examined through a tenfold cross validation with different sets of genotypes and these four QTLs were always detected with 50–90% probability. The final model was evaluated using leave-one-site-out method to assess the influence of site on node addition rate. These analyses provided a quantitative measure of the effects on NAR of common beans exerted by the genetic makeup, the environment and their interactions.
  相似文献   
173.
174.
Regulation of type I phytochrome mRNA abundance   总被引:1,自引:0,他引:1  
  相似文献   
175.
Outer membrane TonB-dependent transducers (TBDTs) actively transport ferric siderophore complexes from the extracellular environment into Gram-negative bacteria. They also participate in a cell-surface signaling regulatory pathway that results in upregulation of the transducer itself, in response to iron-deplete conditions. The TBDT PupB transports ferric pseudobactin, and signals through its N-terminal signaling domain (NTSD), while the TBDT homolog PupA is signaling-inactive. Here, we report the NMR chemical shift assignments of the PupB-NTSD. This information will provide the basis for structural characterization of the PupB-NTSD to further explore its signaling properties.  相似文献   
176.
177.
Recent discoveries and refinements in technique in the field of biochemistry have led to renewed interest in the idea that a test can be developed for the diagnosis of schizophrenia. Studies directed toward that goal have included investigations of biological amines, carbohydrate metabolism, epinephrine metabolism, serotonin, taraxein and ceruloplasmin. No conclusive evidence of any biochemical abnormality in schizophrenia has been found. Although careful studies in adults have failed to confirm a theory that ceruloplasmin levels are abnormally high in schizophrenia, the surmise that it might be true in schizophrenic children was investigated, since constitutional factors seem to be very important in this condition. Thirty-four schizophrenic children and a control group of 13 “behavior problem” children were investigated. No difference was found between the two groups in serum content of copper, ceruloplasmin or ascorbic acid.  相似文献   
178.
In order to assess a new strategy of DNA vaccine for a more complete understanding of its action in immune response, it is important to determine the in vivo biodistribution fate and antigen expression. In previous studies, our group focused on the prophylactic and therapeutic use of a plasmid DNA encoding the Mycobacterium leprae 65-kDa heat shock protein (Hsp65) and achieved an efficient immune response induction as well as protection against virulent M. tuberculosis challenge. In the present study, we examined in vivo tissue distribution of naked DNA-Hsp65 vaccine, the Hsp65 message, genome integration and methylation status of plasmid DNA. The DNA-Hsp65 was detectable in several tissue types, indicating that DNA-Hsp65 disseminates widely throughout the body. The biodistribution was dose-dependent. In contrast, RT-PCR detected the Hsp65 message for at least 15 days in muscle or liver tissue from immunized mice. We also analyzed the methylation status and integration of the injected plasmid DNA into the host cellular genome. The bacterial methylation pattern persisted for at least 6 months, indicating that the plasmid DNA-Hsp65 does not replicate in mammalian tissue, and Southern blot analysis showed that plasmid DNA was not integrated. These results have important implications for the use of DNA-Hsp65 vaccine in a clinical setting and open new perspectives for DNA vaccines and new considerations about the inoculation site and delivery system.  相似文献   
179.
Alternative promoter usage by aldolase A during in vitro myogenesis   总被引:2,自引:0,他引:2  
Aldolase A in the mouse, as in human and rat, shows tissue-specific variability of message size. In addition, in muscle tissue the mRNA size is also developmentally regulated. In order to determine whether this muscle-specific regulatory mechanism can be reproduced in vitro, we have examined the mRNA species of aldolase A isolated from mouse C2C12 myoblasts and myotubes on Northern blots and by primer extension. We show that aldolase A mRNA increases during in vitro myogenesis; that this induction is accompanied by a change in the message population; and that this change is due to activation of a muscle-specific alternative promoter.  相似文献   
180.
A new translocation in Burkitt's tumor cells   总被引:5,自引:0,他引:5  
Summary A t(8;22)(q24;q11) translocation was found in blood, bone marrow, and ascites cells from a European Burkitt's lymphoma. Cell surface markers were identified as monoclonal IgG. The relationship between these two unusual findings is questionable in this cytologically typical Burkitt's lymphoma.  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