全文获取类型
收费全文 | 428篇 |
免费 | 34篇 |
专业分类
462篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 7篇 |
2018年 | 5篇 |
2017年 | 4篇 |
2016年 | 14篇 |
2015年 | 13篇 |
2014年 | 17篇 |
2013年 | 20篇 |
2012年 | 24篇 |
2011年 | 26篇 |
2010年 | 27篇 |
2009年 | 23篇 |
2008年 | 34篇 |
2007年 | 34篇 |
2006年 | 26篇 |
2005年 | 21篇 |
2004年 | 31篇 |
2003年 | 22篇 |
2002年 | 22篇 |
2001年 | 9篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1998年 | 7篇 |
1997年 | 8篇 |
1996年 | 1篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1974年 | 5篇 |
1972年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有462条查询结果,搜索用时 15 毫秒
151.
Hovatta I de Mello VD Kananen L Lindström J Eriksson JG Ilanne-Parikka P Keinänen-Kiukaanniemi S Peltonen M Tuomilehto J Uusitupa M 《PloS one》2012,7(4):e34948
Leukocyte telomere length (TL) is considered a biomarker for biological aging. Shortened TL has been observed in many complex diseases, including type 2 diabetes (T2DM). Lifestyle intervention studies, e.g. the Diabetes Prevention Study (DPS), have shown a decrease in the incidence of T2DM by promoting healthy lifestyles in individuals with impaired glucose tolerance (IGT). Our aim was to study in the DPS the influence of the lifestyle intervention on TL. TL was measured by quantitative PCR-based method at two time points (N = 334 and 343) on average 4.5 years apart during the active intervention and post-intervention follow-up. TL inversely correlated with age. Our main finding was that TL increased in about two thirds of the individuals both in the intervention and in the control groups during follow-up; TL increased most in individuals with the shortest TL at the first measurement. TL was not associated with development of T2DM, nor did lifestyle intervention have an effect on TL. No association between insulin secretion or insulin resistance indices and TL was observed. We did not detect an association between TL and development of T2DM in the DPS participants. It could be due to all participants being overweight and having IGT at baseline, both of which have been found to be independently associated with shorter leukocyte TL in some earlier studies. TL had no substantial role in worsening of glucose tolerance in people with IGT. Our study confirms that leukocyte TL can increase with time even in obese people with impaired glucose metabolism. 相似文献
152.
Viscum album (European mistletoe), a perennial, evergreen, hemiparasitic shrub, infects a wide range of woody species. It adversely affects
the height and diameter of growth and it is associated with increased mortality of its hosts. There is no effective control
methods against it. We have found a specific hyperparasitic fungus, which can completely destroy European mistletoe by infecting
its branches, leaves and berries. Both morphological and molecular identification, based on ribosomal internal transcribed
spacer sequences (rDNA-ITS), established its identity as Phaeobotryosphaeria visci. Our analysis also revealed unexpected ITS variability, as compared to the previous studies, that needs to be considered
in identifying of this pathogen. Because of its efficient pathogenicity this fungus might be a good candidate for biological
control of mistletoe. 相似文献
153.
Lajunen HR Kaprio J Rose RJ Pulkkinen L Silventoinen K 《Obesity (Silver Spring, Md.)》2012,20(3):583-589
To investigate how parental education modifies genetic and environmental influences on variation in BMI during adolescence, self-reported BMI at 11-12, 14, and 17 years of age was collected from a population sample of 2,432 complete Finnish twin pairs born in 1983-1987. Based on parental report, twins were divided to those with high (both parents high school graduates), mixed level (one parent a graduate, the other not), and limited (neither parent a graduate) parental education. Genetic and environmental influences on variation in BMI in different education classes were modeled using twin analysis. Heritability of BMI among 11-12-year-olds with high parental education was 85-87% whereas it was 61-68% if parental education was limited or mixed level. Common environmental effect, i.e., effect of environmental factors shared by family members, was found (17-22%) if parental education was limited or mixed level but not if it was high. With increasing parental education, common environmental variance in BMI decreased at age 14 among boys (from 22 to 3%) and girls (from 17 to 10%); heritability increased among boys from 63 to 78%, but did not change among girls. The common environmental component disappeared and heritability of BMI was larger at the age of 17 in all parental education classes. To conclude, common environment did not affect variation of adolescent BMI in high-educated families but did so in families with limited parental education. This suggests that intervention and prevention campaigns could effectively target families identified by limited parental education. 相似文献
154.
155.
Two papers, one in Nature (Jones et al., 2006) and the other in the Journal of Clinical Investigation (Verma et al., 2006) show that Nck adaptor proteins connect phosphorylated nephrin with actin polymerization in podocyte foot processes, structures important for slit-diaphragm formation in the kidney. Their results further our understanding of podocyte development and repair in glomerular disease. 相似文献
156.
Nikhil Koskinen PE Visa A Kaksonen AH Puhakka JA Yli-Harja O 《Bioprocess and biosystems engineering》2008,31(6):631-640
Clustering hybrid regression (CHR) approach was developed and evaluated using data from H(2)-producing glucose-based, suspended-cell bioreactor operated for 5 months. The aim was to describe the relationship between metabolic end products and H(2)-production rate. Self-organizing maps (SOM) were used to better visualize the dataset and to detect main metabolic patterns in bioprocess data. SOM detected three distinct metabolic patterns with butyrate, acetate and ethanol as dominant metabolites, respectively. Butyrate dominated metabolism was related to high H(2) production, while acetate and ethanol dominated metabolisms resulted in low H(2) production. CHR models performed well [mean square error (MSE) 0.55 and 0.56] in modeling the H(2)-production rate. The results validate the suitability of the CHR approach in describing the bioprocess behavior and in the modeling of H(2) production rate. The developed model can help in discovering key metabolic interactions and suitable process parameters from complex datasets, and increase the understanding of the bioprocesses occurring in engineered and natural environments. 相似文献
157.
Seasonal variation in density of juvenile Atlantic salmon in fluvial shoreline habitats of a large subarctic river 总被引:1,自引:0,他引:1
The densities of Atlantic salmon fry (0+ years) and parr (1+ years and older) in shoreline habitats of the large River Teno watercourse and its tributary, the River Utsjoki generally fluctuated considerably, showing an increase from early summer towards late August and a subsequent decline towards autumn. The seasonal pattern of variation in density was more distinct for parr than for fry. In the period between late July and early September, parr density followed a sinusoidal curve, being highest in late August and lowest in early August and in September. Fry density had a weaker seasonal profile than parr, being highest in late August and in early September. Frequency distributions of the parr age groups (1+, 2+ and 3+ years) were mainly independent of the sampling month. 相似文献
158.
Kontkanen H Saloheimo M Pere J Miettinen-Oinonen A Reinikainen T 《Applied microbiology and biotechnology》2006,72(4):696-704
Melanocarpus albomyces steryl esterase STE1 is considered to be an interesting tool for several industrial applications due to its broad substrate specificity. STE1 was produced in the filamentous fungus Trichoderma reesei in a laboratory bioreactor at an estimated production level of 280 mg l−l. The properties of the purified recombinant enzyme (rSTE1), such as substrate specificity, molecular mass, pH optimum and stability and thermostability, were characterized and compared to the corresponding properties of the native enzyme. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis showed one band with a molecular weight of 60 kDa for rSTE1, whereas analytical gel filtration showed a dimeric structure with a molecular weight of 120 kDa. The rSTE1 was somewhat less stable under different conditions and had slightly lower activities on various substrates than the native STE1. The effects of rSTE1 on the properties of paper sheets and polyethylene terephthalate (PET) fabric were preliminarily evaluated. Due to the hydrolysis of triglycerides and steryl esters by the rSTE1 treatment, the tensile strength and hydrophilicity of the paper were increased. The rSTE1 treatment increased significantly the polarity of PET by hydrolysing the ester bonds in the polyester backbone. Dyeing of PET with methylene blue was also slightly improved after rSTE1 treatment. 相似文献
159.
Brinker M Brosché M Vinocur B Abo-Ogiala A Fayyaz P Janz D Ottow EA Cullmann AD Saborowski J Kangasjärvi J Altman A Polle A 《Plant physiology》2010,154(4):1697-1709
160.
Kilpinen S Autio R Ojala K Iljin K Bucher E Sara H Pisto T Saarela M Skotheim RI Björkman M Mpindi JP Haapa-Paananen S Vainio P Edgren H Wolf M Astola J Nees M Hautaniemi S Kallioniemi O 《Genome biology》2008,9(9):R139-14
Our knowledge on tissue- and disease-specific functions of human genes is rather limited and highly context-specific. Here, we have developed a method for the comparison of mRNA expression levels of most human genes across 9,783 Affymetrix gene expression array experiments representing 43 normal human tissue types, 68 cancer types, and 64 other diseases. This database of gene expression patterns in normal human tissues and pathological conditions covers 113 million datapoints and is available from the GeneSapiens website. 相似文献