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   263篇
  免费   21篇
  2023年   2篇
  2022年   2篇
  2021年   11篇
  2020年   8篇
  2019年   10篇
  2018年   8篇
  2017年   5篇
  2016年   11篇
  2015年   14篇
  2014年   20篇
  2013年   29篇
  2012年   31篇
  2011年   30篇
  2010年   14篇
  2009年   17篇
  2008年   14篇
  2007年   10篇
  2006年   10篇
  2005年   5篇
  2004年   8篇
  2003年   7篇
  2002年   2篇
  2001年   2篇
  2000年   1篇
  1998年   1篇
  1997年   1篇
  1996年   1篇
  1994年   1篇
  1991年   1篇
  1990年   1篇
  1987年   2篇
  1985年   1篇
  1984年   2篇
  1983年   1篇
  1974年   1篇
排序方式: 共有284条查询结果,搜索用时 46 毫秒
51.
Barley plants (Hordeum vulgare L.) received foliar applications of 10–4 M gibberellic acid (GA3) and Kinetin (KN) individually and in combination at one or more of three growth stages: flag leaf appearance (I), ear emergence (II), and the first stage of senescence initiation in the flag leaf (III). Both plant growth regulators (PGR) hastened onset of senescence when sprayed at Stage I and/or Stage II. Treatment at Stage III, either alone or in combination with treatments at the other stages, tended to postpone senescence. Yield components also showed stage-dependent response: Stage I treatment increased the formation of total and bearing tillers, and Stage III treatment improved grain number and weight. However, while GA3 proved more effective than KN, the two together acted antagonistically.  相似文献   
52.
Membrane fusion depends on conserved components and is responsible for organelle biogenesis and vesicular trafficking. Yeast vacuoles are dynamic structures analogous to mammalian lysosomes. We report here that yeast Env7 is a novel palmitoylated protein kinase ortholog that negatively regulates vacuolar membrane fusion. Microscopic and biochemical studies confirmed the localization of tagged Env7 at the vacuolar membrane and implicated membrane association via the palmitoylation of its N-terminal Cys13 to -15. In vitro kinase assays established Env7 as a protein kinase. Site-directed mutagenesis of the Env7 alanine-proline-glutamic acid (APE) motif Glu269 to alanine results in an unstable kinase-dead allele that is stabilized and redistributed to the detergent-resistant fraction by interruption of the proteasome system in vivo. Palmitoylation-deficient Env7C13-15S is also kinase dead and mislocalizes to the cytoplasm. Microscopy studies established that env7Δ is defective in maintaining fragmented vacuoles during hyperosmotic response and in buds. ENV7 function is not redundant with a similar role of vacuolar membrane kinase Yck3, as the two do not share a substrate, and ENV7 is not a suppressor of yck3Δ. Bayesian phylogenetic analyses strongly support ENV7 as an ortholog of the gene encoding human STK16, a Golgi apparatus protein kinase with undefined function. We propose that Env7 function in fusion/fission dynamics may be conserved within the endomembrane system.  相似文献   
53.
Following the importance of antler-type fruiting bodies of Ganoderma lucidum, in this study, the impact of main growth parameters such as ventilation and light on the development of antler-type fruiting bodies has been investigated together with the determination of physico-chemical properties of antler fruiting bodies. For this, the primordia bags of G. lucidum were kept under controlled ventilation to adjust the CO2 produced by the mushrooms owing to its respiration under light and dark conditions. The bioactive compounds such as phenolics, flavonoids, water-soluble polysaccharides and ganoderic acid showed a two-fold increase in the antler-type fruiting bodies as compared to normal kidney-shaped fruiting bodies. It is assumed from this study that the antler type fruiting bodies are developed due to restricted ventilation which causes an increase in the level of CO2 gas in the air as a result of respiration of mushroom. The shape and colour of antler fruiting bodies again dependent on the light provided in the growth chamber. This study also proves that with the manipulation of light and ventilation antler-type fruiting bodies of G. lucidum could be developed with higher quantity of bioactive compounds and with higher antioxidant potential.  相似文献   
54.

Background

We previously demonstrated improved sweating after enzyme replacement therapy (ERT) in Fabry disease using the thermo-regularity sweat and quantitative sudomotor axon reflex tests. Skin-impedance, a measure skin-moisture (sweating), has been used in the clinical evaluation of burns and pressure ulcers using the portable dynamic dermal impedance monitor (DDIM) system.

Methods

We compared skin impedance measurements in hemizygous patients with Fabry disease (22 post 3-years of bi-weekly ERT and 5 ERT naive) and 22 healthy controls. Force compensated skin-moisture values were used for statistical analysis. Outcome measures included 1) moisture reading of the 100th repetitive reading, 2) rate of change, 3) average of 60–110th reading and 4) overall average of all readings.

Results

All outcome measures showed a significant difference in skin-moisture between Fabry patients and control subjects (p < 0.0001). There was no difference between Fabry patients on ERT and patients naïve to ERT. Increased skin-impedance values for the four skin-impedance outcome measures were found in a small number of dermatome test-sites two days post-enzyme infusions.

Conclusion

The instrument portability, ease of its use, a relatively short time required for the assessment, and the fact that DDIM system was able to detect the difference in skin-moisture renders the instrument a useful clinical tool.
  相似文献   
55.
56.
A novel series of CCR5 antagonists has been identified, utilizing leads from high-throughput screening which were further modified based on insights from competitor molecules. Lead optimization was pursued by balancing opposing trends of metabolic stability and potency. Selective and potent analogs with good pharmacokinetic properties were successfully developed.  相似文献   
57.
58.
We present here a novel semi-synthetic cyclic ether fluorinated noscapine analog (CEFNA) that shows potent antiproliferative and anticancer activity in both hormone-responsive (MCF-7) and hormone non-responsive (MDA-MB-231) breast cancer cells. Interestingly, it is also effective against MCF-7/Adr, an adriamycin-resistant variant of MCF-7 cells. Immunofluorescence experiments showed numerous micronuclei, indicative of apoptotic cell death triggered by this novel analog. Mechanistically, CEFNA exerts a strong antimitotic effect as revealed by cell-cycle studies that show a dose-dependent increase in G2/M population preceding a rising sub-G1 population, suggesting apoptosis.  相似文献   
59.
Plant morphological and physiological traits affect the way plants tolerate environmental stresses and therefore play an important role in shaping species distribution patterns in relation to environmental gradients. Despite our growing knowledge on the role of functional traits in structuring plant communities, few studies have tested their importance at large scales in the wet tropics. Here, we describe the distribution patterns of the most important West African rain forest timber species along the regional rainfall gradient and relate them to their functional traits. We found that the distribution patterns of 25 out of the 31 studied species (80%) were significantly related to mean annual rainfall. Shade tolerance and drought resistance were identified as the main strategy axes of variation. Wood density and leaf deciduousness emerged as the best predictor traits of species position along the rainfall gradient, explaining respectively 32 and 15 percent of the variation. Species traits tended to show stronger relationships with estimated optimum annual rainfall for each species than to the extreme rainfall conditions where they occur. The significant role of rainfall in shaping timber species distribution and the strong relationships between species traits and rainfall indicate that changes in climate, especially declining rainfall, could have strong effects on species composition and abundance in these tropical forests.  相似文献   
60.
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