全文获取类型
收费全文 | 350篇 |
免费 | 21篇 |
出版年
2022年 | 2篇 |
2021年 | 7篇 |
2020年 | 5篇 |
2017年 | 5篇 |
2016年 | 9篇 |
2015年 | 18篇 |
2014年 | 24篇 |
2013年 | 27篇 |
2012年 | 26篇 |
2011年 | 35篇 |
2010年 | 14篇 |
2009年 | 10篇 |
2008年 | 19篇 |
2007年 | 15篇 |
2006年 | 15篇 |
2005年 | 20篇 |
2004年 | 18篇 |
2003年 | 12篇 |
2002年 | 9篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 10篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1988年 | 4篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 2篇 |
1968年 | 1篇 |
1965年 | 1篇 |
1963年 | 1篇 |
1961年 | 1篇 |
1956年 | 1篇 |
1955年 | 2篇 |
1951年 | 1篇 |
1950年 | 1篇 |
排序方式: 共有371条查询结果,搜索用时 78 毫秒
121.
Inngjerdingen KT Kiyohara H Matsumoto T Petersen D Michaelsen TE Diallo D Inngjerdingen M Yamada H Paulsen BS 《Phytochemistry》2007,68(7):1046-1058
An immunomodulating pectic polymer, GOA1, obtained from the aerial parts of the Malian medicinal plant Glinus oppositifolius (L.) Aug. DC. (Aizoaceae) has previously been reported to consist of arabinogalactans type I and II, probably linked to a rhamnogalacturonan backbone. To further elucidate the structure of the polymer GOA1, enzymatic degradation studies and weak acid hydrolysis were performed. Five different glycosidases were used, endo-alpha-D-(1-->4)-polygalacturonase, exo-alpha-L-arabinofuranosidase, endo-alpha-L-(1-->5)-arabinanase, endo-beta-D-(1-->4)-galactanase and exo-beta-D-galactosidase. It appears that GOA1 may contain a structural moiety consisting of a 1,3-linked galactopyranosyl (Galp) main chain with 1,6-linked Galp side chains attached to position 6 of the main chain. The 1,6-linked Galp side chain may be branched in position 3 with arabinofuranosyl (Araf) side chains. A 1,4-linked Galp backbone which might carry side chains or glycosyl units attached to position 3 is also a structural element in the polymer. We further show that GOA1 induce proliferation of B cells and the secretion of IL-1beta by macrophages, in addition to a marked increase of mRNA for IFN-gamma in NK-cells. To elucidate structure-activity relations the native polymer and the digested fractions were tested for complement fixing activity and intestinal immune stimulating activity. The partial removal of Araf residues after enzymatic degradations did not affect the bioactivities, while the acid hydrolysed fraction showed reduced complement fixing activity. A decrease in Araf units, 1,3,6-linked Galp units and a partial hydrolysed rhamnogalacturonan backbone, in addition to a reduction in molecular weight are factors that might have contributed to reduced bioactivity. 相似文献
122.
Emilie A. Rennie Berit Ebert Godfrey P. Miles Rebecca E. Cahoon Katy M. Christiansen Solomon Stonebloom Hoda Khatab David Twell Christopher J. Petzold Paul D. Adams Paul Dupree Joshua L. Heazlewood Edgar B. Cahoon Henrik Vibe Scheller 《The Plant cell》2014,26(8):3314-3325
Glycosyl inositol phosphorylceramide (GIPC) sphingolipids are a major class of lipids in fungi, protozoans, and plants. GIPCs are abundant in the plasma membrane in plants, comprising around a quarter of the total lipids in these membranes. Plant GIPCs contain unique glycan decorations that include a conserved glucuronic acid (GlcA) residue and various additional sugars; however, no proteins responsible for glycosylating GIPCs have been identified to date. Here, we show that the Arabidopsis thaliana protein INOSITOL PHOSPHORYLCERAMIDE GLUCURONOSYLTRANSFERASE1 (IPUT1) transfers GlcA from UDP-GlcA to GIPCs. To demonstrate IPUT1 activity, we introduced the IPUT1 gene together with genes for a UDP-glucose dehydrogenase from Arabidopsis and a human UDP-GlcA transporter into a yeast mutant deficient in the endogenous inositol phosphorylceramide (IPC) mannosyltransferase. In this engineered yeast strain, IPUT1 transferred GlcA to IPC. Overexpression or silencing of IPUT1 in Nicotiana benthamiana resulted in an increase or a decrease, respectively, in IPC glucuronosyltransferase activity in vitro. Plants in which IPUT1 was silenced accumulated IPC, the immediate precursor, as well as ceramides and glucosylceramides. Plants overexpressing IPUT1 showed an increased content of GIPCs. Mutations in IPUT1 are not transmitted through pollen, indicating that these sphingolipids are essential in plants. 相似文献
123.
124.
Trine P Ludvigsen Niels Wiinberg Christina J Jensen Annemette T Callesen Regitze W Andersen Anne Sofie H J?rgensen Berit ? Christoffersen Henrik D Pedersen Sophia G Moesgaard Lisbeth H Olsen 《Comparative medicine》2014,64(6):471-477
Few methods for noninvasive assessment of arterial stiffness and endothelial dysfunction in porcine models are available. The aim of this study was to evaluate methods for assessment of arterial stiffness and endothelial dysfunction in anesthetized Göttingen minipigs. Pulse-wave velocity (PWV) was assessed in male Göttingen minipigs (n = 8; age approximately 60 wk) by using applanation tonometry of the carotid and femoral arteries. In addition, flow-mediated vasodilation (FMD) was assessed by using vascular ultrasonography of the brachial artery to evaluate endothelial dysfunction. To evaluate the reproducibility of the methods, minipigs were anesthetized by intravenous infusion of ketamine and midazolam and examined every other day for a total of 3 trials. Neither examination day nor systolic, diastolic, or mean arterial blood pressure statistically influenced PWV or FMD. The median interexamination coefficient of variation was 17% for PWV and 59% for FMD. Measured values of PWV corresponded largely to those in clinically healthy humans, but FMD values were lower than expected for lean, young animals. Although the ketamine–midazolam anesthesia we used has been associated with minor hemodynamic effects in vivo, in vitro studies suggest that both drugs are vasodilatory. Therefore anesthesia might have influenced the endothelial response, contributing to the modest FMD response and the concurrent high coefficients of variation that we noted. We conclude that PWV—but not FMD—showed acceptable interexamination variation for its potential application in porcine models.Abbreviations: FMD, flow-mediated vasodilation; FVI, integrated flow velocity; GTN, glyceryl trinitrate; PWV, pulse-wave velocity; T, transit timeCardiovascular disease has become a global challenge in public health,42 and the development and characterization of comparative animal models are of increasing importance. Several animal models of atherosclerosis, including porcine, have been described.11,12,34 Due to similarities to humans in the anatomy of the cardiovascular system and metabolic physiology, pigs represent a generally useful model in regard to preclinical evaluation and pharmacology.36 Assessment of changes related to atherosclerosis in vivo would be valuable in for example longitudinal assessment of drug effect, but few noninvasive methods for evaluating structural and functional changes in the arteries of pigs are available. In humans, increased arterial stiffness, which occurs with advanced age, also is caused by the pathophysiologic changes associated with atherosclerosis,26 and noninvasive methods for assessing arterial stiffness have been established. The evaluation of pulse-wave velocity (PWV) by using pressure transducers, such as applanation tonometry, is a method recognized as an independent predictor for cardiovascular events in epidemiologic studies.21 The method evaluates the velocity with which the pulse wave is propagated through the arterial tree, with arterial stiffness causing increased velocity.1,22,29,37,39 Flow-mediated vasodilation (FMD), assessed by vascular ultrasonography, represents a noninvasive evaluation of endothelial-dependent vasodilation. A decrease in vasodilation as a response to increased shear stress has been recognized as a marker of endothelial dysfunction, which precedes the development of atherosclerosis.5,7 Recent studies have shown that the FMD method is applicable in large animals (that is, dogs and horses) and that a decreased FMD response occurs in dogs with valvular heart disease.10,15,23,28The aim of this study was to evaluate the reproducibility of methods for assessing arterial stiffness (PWV) and endothelial function (FMD response) in anesthetized Göttingen minipigs, including the influences of arterial blood pressure, heart rate, and room and body temperatures on these methods. 相似文献
125.
Mikkel Z. Ankarfeldt Sofus C. Larsen Lars ?ngquist Lise Lotte N. Husemoen Nina Roswall Kim Overvad Marianne Uhre Jakobsen Jytte Halkj?r Anne Tj?nneland Allan Linneberg Ulla Toft Torben Hansen Oluf Pedersen Berit L. Heitmann Arne Astrup Thorkild I. A. S?rensen 《PloS one》2014,9(10)
Background
Genetic predisposition to adiposity may interact with dietary protein in relation to changes of anthropometry.Objective
To investigate the interaction between genetic predisposition to higher body mass index (BMI), waist circumference (WC) or waist-hip ratio adjusted for BMI (WHRBMI) and dietary protein in relation to subsequent change in body weight (ΔBW) or change in WC (ΔWC).Design
Three different Danish cohorts were used. In total 7,054 individuals constituted the study population with information on diet, 50 single-nucleotide polymorphisms (SNPs) associated with BMI, WC or WHRBMI, as well as potential confounders. Mean follow-up time was ∼5 years. Four genetic predisposition-scores were based on the SNPs; a complete-score including all selected adiposity- associated SNPs, and three scores including BMI, WC or WHRBMI associated polymorphisms, respectively. The association between protein intake and ΔBW or ΔWC were examined and interactions between SNP-score and protein were investigated. Analyses were based on linear regressions using macronutrient substitution models and meta-analyses.Results
When protein replaced carbohydrate, meta-analyses showed no associations with ΔBW (41.0 gram/y/5 energy% protein, [95% CI: −32.3; 114.3]) or ΔWC (<−0.1 mm/y/5 energy % protein, [−1.1; 1.1]). Similarly, there were no interactions for any SNP-scores and protein for either ΔBW (complete SNP-score: 1.8 gram/y/5 energy% protein/risk allele, [−7.0; 10.6]) or ΔWC (complete SNP-score: <0.1 mm/y/5 energy% protein/risk allele, [−0.1; 0.1]). Similar results were seen when protein replaced fat.Conclusion
This study indicates that the genetic predisposition to general and abdominal adiposity, assessed by gene-scores, does not seem to modulate the influence of dietary protein on ΔBW or ΔWC. 相似文献126.
Jeanett Friis Rohde Marie Vik Hessner J?rgen Lous Pia Müller Ulla H?lund Berit Lilienthal Heitmann 《PloS one》2014,9(4)
Background
Several studies suggest that men and women are treated differently for similar disease including diabetes and cardiovascular disease. Differences in attitudes and treatment practices towards men and women with obesity are not well recognized.Objective
To investigate the attitudes and treatment practices among Danish general practitioners (GPs), in relation to treatment of overweight, while taking gender of both the patients and practitioners into account.Design
Questionnaire inventory covertly examining attitudes and practices among Danish general practitioners towards treatment of overweight. All 3.637 general practitioners from the Danish Medical Association register were invited to participate in the survey. In total 1.136 participated.Results
The GPs found weight loss to be more important for overweight male than overweight female patients. They also treated complications to overweight more rigorously among male than female patients, and recommended lipid lowering medicine more often to male than female overweight patients. In addition, the younger female GPs and older male GPs more often said that they would treat an overweight patient with lipid lowering medicine.Conclusion
Among general practitioners in Denmark, treatment for weight loss is more often practiced for overweight male than overweight female patients presenting with same symptoms. In addition, hyperlipidemia among overweight males is also more often treated with lipid lowering medicine than hyperlipidemia among overweight females. 相似文献127.
The amount of ultraviolet (UV) radiation reaching the earth's surface has increased due to depletion of the ozone layer. Several studies have reported that UV radiation reduces survival of fish larvae. However, indirect and sub-lethal impacts of UV radiation on fish behavior have been given little consideration. We observed the escape performance of larval cod (24 dph, SL: 7.6±0.2 mm; 29 dph, SL: 8.2±0.3 mm) that had been exposed to sub-lethal levels of UV radiation vs. unexposed controls. Two predators were used (in separate experiments): two-spotted goby (Gobiusculus flavescens; a suction predator) and lion's mane jellyfish (Cyanea capillata; a "passive" ambush predator). Ten cod larvae were observed in the presence of a predator for 20 minutes using a digital video camera. Trials were replicated 4 times for goby and 5 times for jellyfish. Escape rate (total number of escapes/total number of attacks ×100), escape distance and the number of larvae remaining at the end of the experiment were measured. In the experiment with gobies, in the UV-treated larvae, both escape rate and escape distance (36%, 38±7.5 mm respectively) were significantly lower than those of control larvae (75%, 69±4.7 mm respectively). There was a significant difference in survival as well (UV: 35%, Control: 63%). No apparent escape response was observed, and survival rate was not significantly different, between treatments (UV: 66%, Control: 74%) in the experiment with jellyfish. We conclude that the effect and impact of exposure to sub-lethal levels of UV radiation on the escape performance of cod larvae depends on the type of predator. Our results also suggest that prediction of UV impacts on fish larvae based only on direct effects are underestimations. 相似文献
128.
Background
B cells and humoral immune responses play an important role in the pathogenesis and diagnosis of multiple sclerosis (MS). A characteristic finding in patients with MS is a polyspecific intrathecal B cell response against neurotropic viruses, specifically against measles virus, rubella virus, and varicella zoster virus, also known as an MRZ reaction (MRZR). Here, we correlated from the routine clinical diagnostics individual IgG antibody indices (AIs) of MRZR with magnetic resonance imaging (MRI) findings in patients with first MS diagnosis.Methods/Results
MRZR was determined in 68 patients with a clinically isolated syndrome (CIS) or early relapsing-remitting MS (RRMS). Absolute AI values for measles virus, rubella virus, and varicella zoster virus were correlated with T2 lesion load and gadolinium enhancing lesions on cerebral MRI (cMRI) and cMRI combined with spinal MRI (sMRI). Measles virus AI correlated significantly with T2 lesion load on cMRI (p = 0.0312, Mann-Whitney U test) and the sum of lesions on cMRI and sMRI (p = 0.0413). Varicella zoster virus AI also showed a correlation with T2 lesion load on cMRI but did not reach statistical significance (p = 0.2893).Conclusion
The results confirm MRZR as part of the polyspecific immune reaction in MS with possible prognostic impact on MRI and clinical parameters.Furthermore, the data indicate that intrathecal measles virus IgG production correlates with disease activity on cMRI and sMRI in patients with early MS. 相似文献129.
Berit M Sverdrup Henrik Källberg Lars Klareskog Lars Alfredsson 《Arthritis research & therapy》2012,14(1):R41-7
Introduction
The aim of this study was to investigate the association between exposure to cosmetics, often containing mineral oil, and the risk of developing rheumatoid arthritis (RA). The study was performed against the background that occupational exposure to mineral oil has recently been shown to be associated with an increased risk for RA in man, and that injection of or percutaneous exposure to mineral-oil-containing cosmetics can induce arthritis in certain rat strains.Methods
A population-based case-control study of incident cases of RA was performed among the population aged 18 to 70 years in a defined area of Sweden during May 1996 to December 2003. A case was defined as an individual from the study base, who received for the first time a diagnosis of RA according to the 1987 American College of Rheumatology criteria. Controls were randomly selected from the study base with consideration taken for age, gender and residential area. Cases (n = 1,419) and controls (n = 1,674) answered an extensive questionnaire regarding environmental and lifestyle factors including habits of cosmetic usage. The relative risk of developing RA was calculated for subjects with different cosmetic usage compared with subjects with low or no usage. Analysis was also performed stratifying the cases for presence/absence of rheumatoid factor and antibodies to citrulline-containing peptides.Results
The relative risks of developing RA associated with use of cosmetics were all close to one, both for women and men, for different exposure categories, and in relation to different subgroups of RA.Conclusion
This study does not support the hypothesis that ordinary usage of common cosmetics as body lotions, skin creams, and ointments, often containing mineral oil, increase the risk for RA in the population in general. We cannot exclude, however, that these cosmetics can contribute to arthritis in individuals carrying certain genotypes or simultaneously being exposed to other arthritis-inducing environmental agents. 相似文献130.
The study was conducted in Atlantic salmon to establish the initial and basic scientific documentation for an alternative batch potency test for salmon furuculosis vaccines. We assessed the antibody response development for Aeromonas salmonicida vaccines at different immunisation temperatures (3, 12 and 18 °C), by an enzyme-linked-immunosorbent assay (ELISA) 3, 6, 9 and 12 weeks post vaccination, and the correlation between antibody response and protection in cohabitation challenge experiments performed 6 and 12 weeks post vaccination. Fish immunised with a vaccine containing full antigen dose had a significant increase in antibody response after 252 day degrees and the measured values correlated well with protection after 500 day degrees. Fish vaccinated with a reduced antigen dose showed a significant lower antibody response than fish vaccinated with the full dose vaccine at all samplings, and showed a similar low relative percent survival (RPS) in the challenges. The results from this study indicate that an antibody ELISA can discriminate between vaccines of different antigen content and the method may replace challenge tests in batch potency testing of furunculosis vaccines in Atlantic salmon. An immunisation temperature of 12 °C and sampling after 6-9 weeks, seemed to be the most appropriate time for using antibody responses to confirm batch potency. 相似文献