全文获取类型
收费全文 | 251篇 |
免费 | 9篇 |
出版年
2021年 | 3篇 |
2020年 | 4篇 |
2019年 | 1篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 5篇 |
2015年 | 8篇 |
2014年 | 6篇 |
2013年 | 12篇 |
2012年 | 16篇 |
2011年 | 13篇 |
2010年 | 9篇 |
2009年 | 12篇 |
2008年 | 7篇 |
2007年 | 11篇 |
2006年 | 9篇 |
2005年 | 7篇 |
2004年 | 7篇 |
2003年 | 7篇 |
2002年 | 10篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 8篇 |
1998年 | 1篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1994年 | 1篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 7篇 |
1988年 | 1篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 9篇 |
1978年 | 3篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1969年 | 6篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1965年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有260条查询结果,搜索用时 31 毫秒
101.
102.
José Nicolau Douglas Nesadal De Souza Alyne Simões 《Cell biochemistry and function》2009,27(3):128-134
Diabetes has been implicated in the dryness of the mouth, loss of taste sensation, sialosis, and other disorders of the oral cavity, by impairment of the salivary glands. The aim of the present study was to examine the plasma membrane, microsomal, and homogenate Ca2+‐ATPase activity in the rat submandibular and parotid salivary glands of streptozotocin‐induced diabetes. We have also examined the influence of the acidosis state on this parameter. Diabetes was induced by an intraperitoneal injection of streptozotocin and acidosis was induced by daily injection of NH4Cl. At 15 and 30 days after diabetes induction, the animals were euthanized and the submandibular and parotid salivary glands were removed and analyzed. Ca2+‐ATPase (total, independent, and dependent) was determined in the homogenate, microsomal, and plasma membranes of the salivary glands of diabetic and control rats. Calcium concentration was also determined in the glands and showed to be higher in the diabetic animals. Ca2+‐ATPase activity was found to be reduced in all cell fractions studied in the diabetic animals compared with control. Similar results were obtained for the submandibular salivary glands of acidotic animals; however in the parotid salivary glands it was found an increase in the enzyme activity. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
103.
Several studies have shown the antidiabetic properties of sodium tungstate. In this study, we evaluated some biochemical parameters
of the parotid salivary gland of streptozotocin-induced diabetic rats treated with sodium tungstate solution (2 mg/ml). The
studied groups were: untreated control (UC), treated control (TC), untreated diabetic (UD), and treated diabetic (TD). After
2 and 6 weeks of treatment, parotid gland was removed and total protein and sialic acid (free and total) concentration and
amylase and peroxidase activities were determined. Data were compared by variance analysis and Tukey test (p < 0.05). The sodium tungstate treatment modestly decreased the glycemia of streptozotocin-induced diabetic rats. At week 2
of the study, parotid gland of diabetic rats presented a reduction of total protein concentration (55%) and an increase of
amylase (120%) and peroxidase (160%) activities, free (150%) and total (170%) sialic acid concentration. No alteration in
the evaluated parameters at week 6 of the study was observed. Sodium tungstate presented no significant effect in parotid
gland. Our results suggest that diabetes causes initial modification in biochemical composition of parotid. However, this
gland showed a recovery capacity after 6 week of the experimental time. Sodium tungstate has no effect in peripheral tissues,
such as salivary glands. 相似文献
104.
Opposite effects of tryptophan intake on motor activity in ring doves (diurnal) and rats (nocturnal)
Aparicio S Garau C Nicolau MC Rial RV Esteban S 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2006,144(2):173-179
The role of l-tryptophan as precursor of serotonin and melatonin synthesis on activity-rest rhythm was studied in ring doves, Streptopelia risoria, as a representative of diurnal animals and rats, Rattus norvegicus, as a typical nocturnal one. The animals were housed in cages equipped for horizontal activity recording in a thermostatized chamber and submitted to a 12/12h light/dark photoperiod (lights on at 08:00 h). After acclimatization, the animals received vehicle (methylcellulose) and l-tryptophan (240 mg/kg) by esophagic cannula 2h before the onset of either light or dark phase. Also, oral melatonin (2.5mg/kg) was tested for comparative purposes. After nocturnal l-tryptophan administration, rats showed increased activity (149%), while the opposite occurred in ring doves (39% decrease). No significant changes were found after diurnal l-tryptophan intake in either species. Melatonin produced effects similar to those of l-tryptophan. These results suggest that the effects of l-tryptophan administration are dependent on the nocturnal/diurnal habits of the studied species and, most probably, are mediated by increased melatonin synthesis. 相似文献
105.
106.
107.
Concepcin Iiguez Sebasti Cap‐Bau Ülo Niinemets Heather Stoll Pere Aguil‐Nicolau Jeroni Galms 《The Plant journal : for cell and molecular biology》2020,101(4):897-918
RuBisCO‐catalyzed CO2 fixation is the main source of organic carbon in the biosphere. This enzyme is present in all domains of life in different forms (III, II, and I) and its origin goes back to 3500 Mya, when the atmosphere was anoxygenic. However, the RuBisCO active site also catalyzes oxygenation of ribulose 1,5‐bisphosphate, therefore, the development of oxygenic photosynthesis and the subsequent oxygen‐rich atmosphere promoted the appearance of CO2 concentrating mechanisms (CCMs) and/or the evolution of a more CO2‐specific RuBisCO enzyme. The wide variability in RuBisCO kinetic traits of extant organisms reveals a history of adaptation to the prevailing CO2/O2 concentrations and the thermal environment throughout evolution. Notable differences in the kinetic parameters are found among the different forms of RuBisCO, but the differences are also associated with the presence and type of CCMs within each form, indicative of co‐evolution of RuBisCO and CCMs. Trade‐offs between RuBisCO kinetic traits vary among the RuBisCO forms and also among phylogenetic groups within the same form. These results suggest that different biochemical and structural constraints have operated on each type of RuBisCO during evolution, probably reflecting different environmental selective pressures. In a similar way, variations in carbon isotopic fractionation of the enzyme point to significant differences in its relationship to the CO2 specificity among different RuBisCO forms. A deeper knowledge of the natural variability of RuBisCO catalytic traits and the chemical mechanism of RuBisCO carboxylation and oxygenation reactions raises the possibility of finding unrevealed landscapes in RuBisCO evolution. 相似文献
108.
Vinícius A.F. Lemes Ana Luísa Neves Isabel C. Guazzelli Eliana Frazzatto Christiane Nicolau Maria Lúcia Corrêa-Giannella Gilberto Velho Sandra M.F. Villares 《Gene》2013
Background
The insertion/deletion polymorphism in the gene encoding the angiotensin-converting enzyme (ACE I/D) was associated with arterial hypertension and obesity in adults, but the data in children are scarce and yielded contrasting results. We assessed the impact of the ACE I/D on blood pressure and obesity related traits in a Brazilian cohort of obese children and adolescents.Methods and results
ACE I/D was genotyped in 320 obese children and adolescents (64% of girls) aged 7–16 years, referred for a weight-loss program. We observed an association of the D-allele with blood pressure and with pre-hypertension/hypertension in boys (odds ratio 2.44, 95% C.I. 1.34–4.68, p = 0.005 for a codominant model). The D-allele, insulin resistance and body fat mass had independent and additive effects and explained 14% of the variance of pre-hypertension/hypertension. The BMI, waist circumference, and body fat mass were significantly higher in DD/ID boys than in II boys (p < 0.005). Allelic associations with obesity related traits were independent of the association with blood pressure. No genotype associations were observed in girls.Conclusions
The D-allele of the ACE I/D polymorphism was associated with arterial hypertension and with obesity related traits in boys, but not in girls, in a cohort of obese children and adolescents. These associations were independent of each other, as well as of the effects of other confounding traits such as insulin secretion, insulin sensitivity and glucose tolerance. Our results are in agreement with experimental evidences suggesting that the renin–angiotensin system plays a role in the regulation of visceral adipose tissue accumulation. 相似文献109.
Leijiane F. Sousa Carolina A. Nicolau Pedro S. Peixoto Juliana L. Bernardoni Samella S. Oliveira José Antonio Portes-Junior Rosa Helena V. Mour?o Isa Lima-dos-Santos Ida S. Sano-Martins Hipócrates M. Chalkidis Richard H. Valente Ana M. Moura-da-Silva 《PLoS neglected tropical diseases》2013,7(9)
In Latin America, Bothrops snakes account for most snake bites in humans, and the recommended treatment is administration of multispecific Bothrops antivenom (SAB – soro antibotrópico). However, Bothrops snakes are very diverse with regard to their venom composition, which raises the issue of which venoms should be used as immunizing antigens for the production of pan-specific Bothrops antivenoms. In this study, we simultaneously compared the composition and reactivity with SAB of venoms collected from six species of snakes, distributed in pairs from three distinct phylogenetic clades: Bothrops, Bothropoides and Rhinocerophis. We also evaluated the neutralization of Bothrops atrox venom, which is the species responsible for most snake bites in the Amazon region, but not included in the immunization antigen mixture used to produce SAB. Using mass spectrometric and chromatographic approaches, we observed a lack of similarity in protein composition between the venoms from closely related snakes and a high similarity between the venoms of phylogenetically more distant snakes, suggesting little connection between taxonomic position and venom composition. P-III snake venom metalloproteinases (SVMPs) are the most antigenic toxins in the venoms of snakes from the Bothrops complex, whereas class P-I SVMPs, snake venom serine proteinases and phospholipases A2 reacted with antibodies in lower levels. Low molecular size toxins, such as disintegrins and bradykinin-potentiating peptides, were poorly antigenic. Toxins from the same protein family showed antigenic cross-reactivity among venoms from different species; SAB was efficient in neutralizing the B. atrox venom major toxins. Thus, we suggest that it is possible to obtain pan-specific effective antivenoms for Bothrops envenomations through immunization with venoms from only a few species of snakes, if these venoms contain protein classes that are representative of all species to which the antivenom is targeted. 相似文献
110.
Roger Mallol Miguel A. Rodr��guez Mercedes Heras Maria Vinaixa Nicolau Ca?ellas Jes��s Brezmes N��ria Plana Llu��s Masana Xavier Correig 《Metabolomics : Official journal of the Metabolomic Society》2011,7(4):572-582
Determining the concentration and size of lipoprotein complexes is very important due to their role in cardiovascular diseases
and metabolic disorders. However, standard methods for lipoprotein fractionation are manual and time consuming and cannot
be used as standard diagnostic tools. Because different subclasses of lipoproteins have different radii and, hence, different
diffusion velocities, we propose a fast and reliable method that uses 2D diffusion-edited 1H NMR spectroscopy to acquire a set of 2D spectra of plasma samples, followed by a surface fitting algorithm based on Lorentzian
functions to estimate the sizes and the relative proportions of different lipoprotein subclasses. We were able to demonstrate
that the derived sizes and positions related to the Lorentzian functions follow an exponential relationship for normolipidaemic
and dislipaemic samples with coefficients of determination (r
2) of 0.85 and 0.81, respectively. Moreover, we found a linear relationship between the width and size of the Lorentzian functions
for normolipidaemic samples (r
2 = 0.88) while for dislipaemic samples this relation was nonlinear (r
2 = 0.62). Dividing our samples set into four different lipoprotein profiles (normal lipid values, low HDL/LDL ratio, high
triglycerides values and both risk factors) and using principal component analysis (PCA) followed by multivariate analysis
of variance (MANOVA), our method was able to statistically discriminate between those groups, with p-values of 0.0016, 0.0006, <1e−4 and 0.0035, respectively. These parameters are characteristic and indicative of different lipoprotein profiles and can be
used to distinguish between normolipidaemic, hypercholesterolaemic, hypertriglyceridaemic and chylomicronaemic profiles. 相似文献