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   1728篇
  免费   104篇
  1832篇
  2023年   11篇
  2022年   32篇
  2021年   45篇
  2020年   31篇
  2019年   43篇
  2018年   64篇
  2017年   56篇
  2016年   67篇
  2015年   103篇
  2014年   105篇
  2013年   168篇
  2012年   163篇
  2011年   147篇
  2010年   87篇
  2009年   78篇
  2008年   96篇
  2007年   77篇
  2006年   83篇
  2005年   48篇
  2004年   47篇
  2003年   71篇
  2002年   46篇
  2001年   10篇
  2000年   10篇
  1999年   12篇
  1998年   9篇
  1997年   11篇
  1996年   7篇
  1995年   13篇
  1994年   5篇
  1993年   7篇
  1992年   10篇
  1991年   9篇
  1990年   7篇
  1989年   6篇
  1988年   5篇
  1987年   10篇
  1986年   2篇
  1985年   4篇
  1984年   3篇
  1983年   4篇
  1982年   2篇
  1981年   2篇
  1979年   2篇
  1978年   2篇
  1977年   2篇
  1974年   2篇
  1967年   1篇
  1965年   1篇
  1907年   1篇
排序方式: 共有1832条查询结果,搜索用时 0 毫秒
1.
A range of debilitating human diseases is known to be associated with the formation of stable highly organized protein aggregates known as amyloid fibrils. The early prefibrillar aggregates behave as cytotoxic agents and their toxicity appears to result from an intrinsic ability to impair fundamental cellular processes by interacting with cellular membranes, causing oxidative stress and increase in free Ca2+ that lead to apoptotic or necrotic cell death. However, specific signaling pathways that underlie amyloid pathogenicity remain still unclear. This work aimed to clarify cell impairment induced by amyloid aggregated. To this end, we used a combined proteomic and one‐dimensional 1H‐NMR approach on NIH‐3T3 cells exposed to prefibrillar aggregates from the amyloidogenic apomyoglobin mutant W7FW14F. The results indicated that cell exposure to prefibrillar aggregates induces changes of the expression level of proteins and metabolites involved in stress response. The majority of the proteins and metabolites detected are reported to be related to oxidative stress, perturbation of calcium homeostasis, apoptotic and survival pathways, and membrane damage. In conclusion, the combined proteomic and 1H‐NMR metabonomic approach, described in this study, contributes to unveil novel proteins and metabolites that could take part to the general framework of the toxicity induced by amyloid aggregates. These findings offer new insights in therapeutic and diagnostic opportunities. J. Cell. Physiol. 228: 1359–1367, 2013. © 2012 Wiley Periodicals, Inc.  相似文献   
2.
Root structure parameters, root biomass and allometric relationships between above- and belowground biomass were investigated in young Norway spruce (Picea abies [L.] Karst.) trees cultivated inside the glass domes with ambient (AC, 375 μmol(CO2) mol?1) and elevated (EC, A + 375 μmol(CO2) mol?1) atmospheric CO2 concentrations ([CO2]). After 8 years of fumigation, a mean EC tree in comparison with AC one exhibited about 37 % higher belowground biomass. The growth of primary root structure was unaffected by elevated [CO2]; however, the biomass of secondary roots growing on the primary root structure and the biomass of secondary roots growing in the zone between the soil surface and the first primary root ramification were significantly higher in EC comparing with AC treatment about 58 and 70 %, respectively. The finest root’s (diameter up to 1 mm) biomass as well as length and surface area of both primary and secondary root structures showed the highest difference between the treatments; advancing EC to AC by 43 % on average. Therefore, Norway spruce trees cultivated under well-watered and rather nitrogen-poor soil conditions responded to the air elevated [CO2] environment by the enhancement of the secondary root structure increment, by enlargement of root length and root absorbing area, and also by alternation of root to aboveground organ biomass proportion. Higher root to leaf and root to stem basal area ratios could be beneficial for Norway spruce trees to survive periods with limited soil water availability.  相似文献   
3.
Beneficial effects of whole grains of cereals and pseudocereals and their fractions to human physiology are well known and broadly published. Especially secondary metabolites, dominantly from the category of phenolics (or polyphenols), beneficially influence the health physiology and/or prevent disease progress. Within the frame of this study, ten genotypes of four cereals or pseudocereals, respectively, were chosen for their antioxidant activity, determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and β-carotene-linoleic acid bleaching model (BCLM) mechanisms. Tested genotypes were selected from primary collection based on their antioxidant activity values, as well as higher level of flavonoids or phenolic acids. The stability of antioxidant properties after thermic, acidic, and basic treatments was evaluated. The oat cultivar Sirene and buckwheat cultivar Bogatyr expressed high level of the antioxidant activity, but they lost it due to all types of treatment. Oppositely, treatments increased antioxidant activities in some samples, especially in oat cultivar Maris Oberon, wheat cultivar Ines and Karolinum, or partially in barley cultivars Kompakt (after basic treatment) and Jubilant (acidic and basic treatments). The lack of the antioxidant activity could be observed due to destruction of the key compounds responsible for the antioxidant effect, whereas the increasing activity could be seen due to release of the aglycons from glycosidic forms after treatment. The stability of antioxidant properties could be a valuable parameter of the raw material for manufacturing special foods with functional properties.  相似文献   
4.
5.
Ecosystems - The origin of resources supporting metazoan biomass in rivers has long been a subject of debate. The river wave concept (RWC) postulates that the energetic basis of food webs varies...  相似文献   
6.
An adult male raccoon dog (Nyctereutes procyonoides Gray, 1834) run over by a car was found on September 6, 2002, in the central part of the Former Yugoslav Republic of Macedonia (UTM: EM 54). This is the first record of this species on the territory of the FYRM, and the southernmost point of its European range so far. This finding indicates a range extension of the raccoon dog on the Balkan Peninsula.  相似文献   
7.
8.
9.
10.
Journal of Plant Growth Regulation - Over the last years, cytokinin deficiency has been studied in a variety of plant species, using transgenic expression of cytokinin oxidase/dehydrogenase genes...  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