全文获取类型
收费全文 | 475篇 |
免费 | 36篇 |
出版年
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 7篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 9篇 |
2015年 | 18篇 |
2014年 | 12篇 |
2013年 | 15篇 |
2012年 | 19篇 |
2011年 | 32篇 |
2010年 | 23篇 |
2009年 | 20篇 |
2008年 | 22篇 |
2007年 | 21篇 |
2006年 | 33篇 |
2005年 | 16篇 |
2004年 | 26篇 |
2003年 | 33篇 |
2002年 | 22篇 |
2001年 | 9篇 |
2000年 | 11篇 |
1999年 | 10篇 |
1998年 | 8篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1991年 | 7篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 10篇 |
1982年 | 5篇 |
1981年 | 7篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1971年 | 3篇 |
1967年 | 2篇 |
1964年 | 3篇 |
排序方式: 共有511条查询结果,搜索用时 31 毫秒
101.
Stig Pramming Birger Thorsteinsson Bent Stigsby Christian Binder 《BMJ (Clinical research ed.)》1988,296(6623):665-667
The relation between blood glucose concentration, the symptoms and signs of hypoglycaemia, and electroencephalographic changes in diabetic patients is not known. The effect of hypoglycaemia on brain function was studied in 13 patients with insulin dependent diabetes. During a gradual fall in blood glucose concentration induced by a bolus injection of insulin followed by an intravenous infusion of insulin, during 60 minutes of biochemical hypoglycaemia, and after restoration of normoglycaemia with intravenous glucose electroencephalograms were evaluated continuously by period-amplitude analysis; blood samples were taken every 10 minutes throughout. No changes were seen in electroencephalograms when the blood glucose concentration was above 3 mmol/l. At a median blood glucose concentration of 2·0 (95% confidence interval 1·7 to 2·3) mmol/l alpha activity decreased abruptly in the electroencephalograms concomitant with an increase in theta activity, reflecting neuronal dysfunction in the cortex. When the blood glucose concentration was further lowered changes were observed in the electroencephalograms indicating that deeper brain structures were affected. A normal electroencephalogram was re-established at a blood glucose concentration of 2·0 (1·8 to 2·1) mmol/l. There was no significant correlation between the blood glucose concentration at the onset of changes in the electroencephalograms and age, duration of diabetes, insulin dose, haemoglobin A1c concentration, initial blood glucose concentration, rate of fall in blood glucose concentration, and appearance of symptoms and signs of hypoglycaemia.Changes in electroencephalograms during hypoglycaemia appear and disappear at such a narrow range of blood glucose concentrations that the term threshold blood glucose concentration for the onset of such changes seems justified. 相似文献
102.
Direct mechanics assessment of elastic symmetries and properties of trabecular bone architecture 总被引:14,自引:0,他引:14
A method is presented to find orthotropic elastic symmetries and constants directly from the elastic coefficients in the overall stiffness matrix of trabecular bone test specimens. Contrary to earlier developed techniques, this method does not require pure orthotropic behavior or additional fabric measurements. The method uses high-resolution computer reconstructions of trabecular bone specimens as input for large-scale FE-analyses to determine all the 21 elastic coefficients in the overall stiffness matrix of the specimen, using a direct mechanics approach. An optimization procedure is then used to find the coordinate transformation that yields the best orthotropic representation of this matrix. The method is illustrated here relative to two trabecular bone specimens. The techniques developed here can be used to obtain a complete characterization of the mechanical properties of trabecular architecture. With the development of in vivo reconstruction techniques, even in vivo measurements will be possible. 相似文献
103.
Bent Friis Theisen Bent Christensen Peter Arctander 《Journal of evolutionary biology》1995,8(1):71-80
Variation in PGM (phosphoglucomutase) and MDH (malate dehydrogenase) allozymes and in mitochondrial and nuclear (ribosomal) DNA gives evidence of at least three independent origins of triploid Trichoniscus pusillus pusillus. Much of the genetic variation found may reflect variation within the parental diploid population(s), but it is argued that some of the variation in PGM allozymes have accumulated within the parthenogenetic lines. Based upon the variation at this locus, 15 genetically distinct clones are distinguished. 相似文献
104.
E. van de Vosse Brunella Franco P. van der Bent Eugenio Montini Ulrike Orth Andre Hanauer N. Tijmes G.-J. B. van Ommen Andrea Ballabio J. T. den Dunnen Arthur A. B. Bergen 《Human genetics》1997,101(2):235-237
X-linked juvenile retinoschisis (RS) is a progressive vitreoretinal degeneration localised in Xp22.1-p22.2. A human homologue
of the retinal degeneration gene C (rdgC), a gene that in Drosophila melanogaster prevents light-induced retinal degeneration, was localised in the RS obligate gene region. We have tested the gene, designated
PPEF in humans, as a candidate gene in RS patients using RT-PCR and the protein truncation test on RNA and SSCP on DNA. No mutations
were identified, making it highly unlikely that PPEF is the gene implicated in RS. The data presented facilitate mutation analysis of the PPEF gene in other diseases which have been or will be localised to this region.
Received: 20 May 1997 / Accepted: 30 July 1997 相似文献
105.
Two iridoid glycosides have been isolated from Viburnum betulifolium. Viburnalloside, the major leaf glycoside, is composed of an iridoid aglucone acylated at C-1 with isovaleric acid and with a di-O-acetyl-β-D-allopyranosyl moiety attached through a glycosidic bond to C-11. Decapetaloside (10-hydroxyiridodial glucoside) has been isolated from the bark. The structure and absolute configuration of viburnalloside have been established by spectroscopic means, and those of decapetaloside by chemical correlation with adoxoside. 相似文献
106.
107.
Tue Wenzel Kragstrup Babak Jalilian Kresten Krarup Keller Xianwei Zhang Julie Kristine Laustsen Kristian Stengaard-Pedersen Merete Lund Hetland Kim H?rslev-Petersen Peter Junker Mikkel ?stergaard Ellen-Margrethe Hauge Malene Hvid Thomas Vorup-Jensen Bent Deleuran 《PloS one》2016,11(2)
Introduction
In rheumatoid arthritis (RA) immune activation and presence of autoantibodies may precede clinical onset of disease, and joint destruction can progress despite remission. However, the underlying temporal changes of such immune system abnormalities in the inflammatory response during treat-to-target strategies remain poorly understood. We have previously reported low levels of the soluble form of CD18 (sCD18) in plasma from patients with chronic RA and spondyloarthritis. Here, we study the changes of sCD18 before and during treatment of early RA and following arthritis induction in murine models of rheumatoid arthritis.Methods
The level of sCD18 was analyzed with a time-resolved immunoflourometric assay in 1) plasma from early treatment naïve RA patients during a treat-to-target strategy (the OPERA cohort), 2) plasma from chronic RA patients, 3) serum from SKG and CIA mice following arthritis induction, and 4) supernatants from synovial fluid mononuclear cells (SFMCs) and peripheral blood mononuclear cells (PBMCs) from 6 RA patients cultured with TNFα or adalimumab.Results
Plasma levels of sCD18 were decreased in chronic RA patients compared with early RA patients and in early RA patients compared with healthy controls. After 12 months of treatment the levels in early RA patients were similar to healthy controls. This normalization of plasma sCD18 levels was more pronounced in patients with very early disease who achieved an early ACR response. Plasma sCD18 levels were associated with radiographic progression. Correspondingly, the serum level of sCD18 was decreased in SKG mice 6 weeks after arthritis induction compared with healthy littermates. The sCD18 levels in both SKG and CIA mice exhibited a biphasic course after arthritis induction with an initial increase above baseline followed by a decline. Shedding of CD18 from RA SFMC and RA PBMC cultures was increased by TNFα and decreased by adalimumab.Conclusions
The plasma sCD18 levels were altered in patients with RA, in mice with autoimmune arthritis and in cell cultures treated with TNFα and adalimumab. Decreased levels of plasma sCD18 could reflect autoimmunity in transition from early to chronic disease and normalization in response to treatment could reflect autoimmunity in remission. 相似文献108.
Bent Borg Jensen 《Archives of microbiology》1990,154(1):92-98
We have investigated the utilization of [14C]-fructose by whole filaments and isolated heterocysts of Anabaena variabilis ATCC 29413, a strain which is capable of fructose-dependent heterotrophic growth. The experimental conditions were chosen such that both transport and subsequent metabolism were studied. The apparent Km for fructose was 60 mM, close to the results of previous studies. Rates of fructose utilization were the same in light and darkness. When photosynthetic CO2 fixation was possible, almost all the label appeared as cell-carbon. In darkness or in the presence of DCMU appreciable amounts of label were released as CO2. Isolated heterocysts with high rates of endogenous metabolism were not capable of utilizing added fructose at significant rates. The effects of oxygen concentration on the metabolism of added fructose in darkness showed that uptake was saturated at low pO2 values. Increasing the pO2 values lead to an increase in the ratio between the lable released as CO2 and that recovred as cell-carbon. These results suggest that fructose is taken up only by the vegetative cells but carbon derived from added fructose can be released as CO2 as a result of respiration in the heterocysts. Fructose utilization was inhibited by uncouplers. The greatest inhibition was found when both (delta) (psi) and (delta) pH were abolished. High concentrations of erythrose inhibited fructose utilization. None of the other potential analogs tested had any effect. 相似文献
109.
110.
Jesper Larsen Henrik Lund-Andersen Bent Krogsaa 《Bulletin of mathematical biology》1983,45(5):749-758
A mathematical model of the transport of fluorescein across the blood-retina barrier in the transient state and the subsequent
diffusion of fluorescein in the vitreous body is presented. The function of the barrier is lumped in a single parameter—the
permeability. The sensitivity of this parameter due to changes in the other parameters of the model is given. This establishes
the foundation for the quantitative assessment of the barrier function through vitreous fluorophotometry. 相似文献