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   139篇
  免费   10篇
  2022年   1篇
  2021年   3篇
  2020年   1篇
  2019年   5篇
  2018年   1篇
  2017年   2篇
  2016年   4篇
  2015年   6篇
  2014年   12篇
  2013年   8篇
  2012年   6篇
  2011年   5篇
  2010年   6篇
  2009年   6篇
  2008年   11篇
  2007年   8篇
  2006年   9篇
  2005年   8篇
  2004年   4篇
  2003年   1篇
  2002年   5篇
  2001年   5篇
  2000年   2篇
  1999年   3篇
  1998年   3篇
  1997年   3篇
  1996年   4篇
  1995年   2篇
  1994年   1篇
  1993年   1篇
  1992年   1篇
  1991年   2篇
  1988年   1篇
  1987年   1篇
  1986年   2篇
  1985年   1篇
  1977年   1篇
  1976年   3篇
  1975年   1篇
排序方式: 共有149条查询结果,搜索用时 46 毫秒
111.

Background

Insulin resistance and diabetes are associated with increased oxidative stress and impairment of cellular defence systems. Our purpose was to investigate the interaction between glucose metabolism, antioxidative capacity and heat shock protein (HSP) defence in different skeletal muscle phenotypes among middle-aged obese subjects during a long-term exercise and dietary intervention. As a sub-study of the Finnish Diabetes Prevention Study (DPS), 22 persons with impaired glucose tolerance (IGT) taking part in the intervention volunteered to give samples from the vastus lateralis muscle. Subjects were divided into two sub-groups (IGTslow and IGTfast) on the basis of their baseline myosin heavy chain profile. Glucose metabolism, oxidative stress and HSP expressions were measured before and after the 2-year intervention.

Results

Exercise training, combined with dietary counselling, increased the expression of mitochondrial chaperones HSP60 and glucose-regulated protein 75 (GRP75) in the vastus lateralis muscle in the IGTslow group and that of HSP60 in the IGTfast group. In cytoplasmic chaperones HSP72 or HSP90 no changes took place. In the IGTslow group, a significant positive correlation between the increased muscle content of HSP60 and the oxygen radical absorbing capacity values and, in the IGTfast group, between the improved VO2max value and the increased protein expression of GRP75 were found. Serum uric acid concentrations decreased in both sub-groups and serum protein carbonyl concentrations decreased in the IGTfast group.

Conclusion

The 2-year intervention up-regulated mitochondrial HSP expressions in middle-aged subjects with impaired glucose tolerance. These improvements, however, were not correlated directly with enhanced glucose tolerance.  相似文献   
112.
113.

Background  

Life Science Identifiers (LSIDs) are persistent, globally unique identifiers for biological objects. The decentralised nature of LSIDs makes them attractive for identifying distributed resources. Data of interest to biodiversity researchers (including specimen records, images, taxonomic names, and DNA sequences) are distributed over many different providers, and this community has adopted LSIDs as the identifier of choice.  相似文献   
114.
Characteristics of 13 newly isolated thermophilic, anaerobic, and cellulolytic strains were compared with previously described strains of Clostridium thermocellum: ATCC 27405 and JW20 (ATCC 31549). Colony morphology, antibiotic sensitivity, fermentation end-products, and cellulose degradation were documented. All 13 strains were sensitive to erythromycin (5 μg/ml) and chloramphenicol (25 μg/ml), and all strains but one were sensitive to kanamycin (20 μg/ml). Polymerase chain reaction (PCR) amplification using primers based on gene sequences from C. thermocellum ATCC 27405 was successful for all 13 strains in the case of the hydrogenase gene and 11 strains in the case of phosphotransacetylase/acetate kinase genes. Ten strains amplified a product of the expected size with primers developed to be specific for C. thermocellum 16SrRNA primers. Two of the 13 strains did not amplify any product with the PCR primers designed for the phosphotransacetylase/acetate kinase and 16SrRNA primers. A MboI-like GATC- recognizing restriction activity was present in all of the five strains examined. The results of this study have several positive implications with respect to future development of a transformation system for cellulolytic thermophiles. Journal of Industrial Microbiology & Biotechnology (2001) 27, 275–280. Received 12 September 2000/ Accepted in revised form 20 November 2000  相似文献   
115.
We describe relationships between the bioclimates and vegetation of the northwest of Mexico, including the Baja California peninsula and the stretch of the Pacific basin between the states of Sonora and Colima, a transition zone from the most arid deserts of North America to tropical rainforests. Links were inferred from temperature and rainfall data obtained from 453 weather stations that were used to construct climatograms, calculate several climate indices and describe main latitudinal and longitudinal trends, and from sampling the vegetation around these stations. Across this extensive area, spanning some 14° of both latitude and longitude as well as three zonobiomes and two zonoecotones, two macrobioclimates were identified, Mediterranean and Tropical, within which we were able to distinguish six bioclimates. For each of these bioclimates, we find different types of zonal and azonal vegetation, whose floristic composition and physiognomy are described here.  相似文献   
116.
FT-IR spectroscopy has being a widespread technique in the agro-industry for the quick assess of food components, including the wine. Using the region of wavenumbers 1200–800 cm−1 of the FT-IR spectra wine polysaccharides, Partial Least Squares Regression (PLS1) independent calibration models were built for mannose quantification in complex matrices from white and in red wine extracts. With PLS1 it was not possible to build a calibration model that included both white and red wine extracts. However, a predictive ability of the model for quantification of mannose from mannoproteins based on this FT-IR spectral region was achieved by the application of orthogonal signal correction (OSC)-PLS1.  相似文献   
117.
118.
Geographical information for 703 mosses and Senecios (species of the tribe Senecioneae, Asteraceae) has been analyzed to identify patterns of species richness in the Transmexican Volcanic Belt (TMVB) of Mexico. Because the TMVB holds a high proportion of these taxa (596 mosses out of 980, and 107 Senecios out of 228) in the country, it is considered a high diversity area. However, the biodiversity is not uniform, as shown by the number of species in each of seventy nine 0.5° latitude and 0.5° longitude cells covering the surface area of the mountain range. Nineteen cells were identified as hotspots and further analysis showed that 11 of such hotspots were common to both groups. The application of a heuristic iterative method and a complementarity criterion indicated that the selection of 18 cells would conserve the total diversity of mosses and Senecios found in such hotspots.  相似文献   
119.
The evolutionary consequences of individual genetic diversity are frequently studied by assessing heterozygosity–fitness correlations (HFCs). The prevalence of positive and negative HFCs and the predominance of general versus local effects in wild populations are far from understood, partly because comprehensive studies testing for both inbreeding and outbreeding depression are lacking. We studied a genetically diverse population of blue tits in southern Germany using a genome‐wide set of 87 microsatellites to investigate the relationship between proxies of reproductive success and measures of multilocus and single‐locus individual heterozygosity (MLH and SLH). We used complimentary measures of MLH and partitioned markers into functional categories according to their position in the blue tit genome. HFCs based on MLH were consistently negative for functional loci, whereas correlations were rather inconsistent for loci found in nonfunctional areas of the genome. Clutch size was the only reproductive variable showing a general effect. We found evidence for local effects for three measures of reproductive success: arrival date at the breeding site, the probability of breeding at the study site and male reproductive success. For these, we observed consistent, and relatively strong, negative effects at one functional locus. Remarkably, this marker had a similar effect in another blue tit population from Austria (~400 km to the east). We suggest that a genetic local effect on timing of arrival might be responsible for most negative HFCs detected, with carry‐over effects on other reproductive traits. This effect could reflect individual differences in the distance between overwintering areas and breeding sites.  相似文献   
120.
In the present study, the continuous application of an artificial long-day photoperiod to induce a refractory state affecting the recovery of post-partum ovulatory activity in subtropical Creole does kidding in autumn, was investigated. For this purpose, a group of does was kept under a natural photoperiod from parturition up to 158 days of lactation (control group: n = 16). The other group was subjected to an artificial long-day photoperiod (16 h light:8 h darkness; treated group: n = 16) from day 10 to 158 of lactation. For the first 96 days postpartum, all does from both the control and treatment groups did not show ovulation. However, from day 108 to 156 post-partum, the proportion of does that exhibited ovulation was greater (P < 0.01) in the treated group (11/16; 69%), than in the control group (2/16; 12.5%). In addition, the does in the treated group produced 15% more milk on average than the does in the control group at 60 and 90 days of lactation (P < 0.001). The body weight and body condition were not affected by the photoperiod treatment (P > 0.05). It could be concluded that, for subtropical lactating does that gave birth in autumn, continuous exposure to an artificial long-day photoperiod induces post-partum ovulatory activity after 150 days of exposure. This behaviour is probably attributable to the induction of a refractory state of the ovary, following continuous exposure to the artificial long days. Furthermore, this photoperiod treatment also increased the milk production level in goats at 60 and 90 days of lactation.  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