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   97篇
  免费   12篇
  国内免费   1篇
  2022年   2篇
  2021年   1篇
  2020年   1篇
  2019年   1篇
  2018年   2篇
  2017年   1篇
  2016年   2篇
  2015年   2篇
  2014年   4篇
  2013年   2篇
  2012年   10篇
  2011年   3篇
  2010年   6篇
  2009年   3篇
  2008年   7篇
  2007年   11篇
  2006年   2篇
  2005年   3篇
  2004年   6篇
  2003年   2篇
  2002年   1篇
  2001年   2篇
  2000年   1篇
  1999年   2篇
  1998年   3篇
  1993年   1篇
  1992年   1篇
  1991年   2篇
  1990年   1篇
  1989年   1篇
  1987年   2篇
  1986年   2篇
  1985年   2篇
  1984年   1篇
  1983年   2篇
  1982年   1篇
  1981年   3篇
  1980年   2篇
  1978年   1篇
  1977年   1篇
  1975年   1篇
  1974年   1篇
  1973年   2篇
  1970年   1篇
  1969年   1篇
  1967年   1篇
排序方式: 共有110条查询结果,搜索用时 15 毫秒
51.
This article documents the addition of 96 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Clarias batrachus, Marmota himalayana, Schizothorax richardsonii, Sitophilus zeamais and Syagrus romanzoffiana. These loci were cross‐tested on the following species: Clarias dussumeri, Clarias gariepinus, Heteropneustus fossilis, Sitophilus granarius and Sitophilus oryzae.  相似文献   
52.
This article documents the addition of 299 microsatellite marker loci and nine pairs of single-nucleotide polymorphism (SNP) EPIC primers to the Molecular Ecology Resources (MER) Database. Loci were developed for the following species: Alosa pseudoharengus, Alosa aestivalis, Aphis spiraecola, Argopecten purpuratus, Coreoleuciscus splendidus, Garra gotyla, Hippodamia convergens, Linnaea borealis, Menippe mercenaria, Menippe adina, Parus major, Pinus densiflora, Portunus trituberculatus, Procontarinia mangiferae, Rhynchophorus ferrugineus, Schizothorax richardsonii, Scophthalmus rhombus, Tetraponera aethiops, Thaumetopoea pityocampa, Tuta absoluta and Ugni molinae. These loci were cross-tested on the following species: Barilius bendelisis, Chiromantes haematocheir, Eriocheir sinensis, Eucalyptus camaldulensis, Eucalyptus cladocalix, Eucalyptus globulus, Garra litaninsis vishwanath, Garra para lissorhynchus, Guindilla trinervis, Hemigrapsus sanguineus, Luma chequen. Guayaba, Myrceugenia colchagüensis, Myrceugenia correifolia, Myrceugenia exsucca, Parasesarma plicatum, Parus major, Portunus pelagicus, Psidium guayaba, Schizothorax richardsonii, Scophthalmus maximus, Tetraponera latifrons, Thaumetopoea bonjeani, Thaumetopoea ispartensis, Thaumetopoea libanotica, Thaumetopoea pinivora, Thaumetopoea pityocampa ena clade, Thaumetopoea solitaria, Thaumetopoea wilkinsoni and Tor putitora. This article also documents the addition of nine EPIC primer pairs for Euphaea decorata, Euphaea formosa, Euphaea ornata and Euphaea yayeyamana.  相似文献   
53.
As part of an ongoing study on the GABAA receptor complex in the developing chick optic tectum we describe some properties of the agonist site, as labeled by [3H]muscimol, including methodological, kinetic and pharmacological aspects. 16-day embryos and 10-day chicks have been selected as representative age points for the initial characterization of the receptor, prior to more detailed developmental studies. Our data indicate the existence, in both embryos and young birds, of a single class of statistically equivalent, high-affinity, saturable binding sites, with a dissociation constant (Kd) of 80–90 nM in freeze-thawed/washed membranes, and about 8 nM in membranes additionally extracted with low concentrations of Triton X-100. Maximal densities of binding sites are nearly identical in both membrane preparations, ranging from 2 to 3 pmol/mg for the two age points considered.

The pharmacological profiles suggest that avian receptors for [3H]muscimol are generally similar to the corresponding mammalian sites, behaving as typical bicuculline-sensitive, baclofen-insensitive type A GABA receptor sites. However, bicuculline and its derivatives are less efficient displacers of [3H]muscimol in detergent-extracted membrane preparations, being in all cases, as usually, much less effective displacers than GABA agonists.

The effect of Triton X-100 on the muscimol site in the GABAA receptor, increasing the affinity for the radioligand by a factor of 10, and diminishing the efficiency of antagonists, is considered here in terms of structural changes in the receptor, induced by the action of the detergent on the membrane microenvironment.  相似文献   

54.
55.
Hypothalamo‐pituitary‐adrenal axis has been reported to influence fat mass distribution in obesity. We investigated the hypothesis that corticosteroid‐binding globulin (CBG) polymorphism could influence obesity, metabolic, or hypothalamo‐pituitary adrenal (HPA) axis activity parameters. In 44 obese pre‐menopausal women, a microsatellite located within the CBG gene was analyzed, providing three genotypes: 86/86 (n = 29), 86/90 (n = 14), and 90/90 (n = 1). No significant difference was found for obesity, metabolic, and HPA axis activity parameters between the genotypes 86/86 and 86/90. Looking for differences in correlations between HPA axis activity parameters and obesity or metabolic parameters between the two genotypes, genotype 86/90 showed a strong correlation between salivary cortisol after dexamethasone (0.25 mg) suppression test and waist‐to‐hip ratio (r = ?0.84, p = 0.0007), whereas this correlation was weaker for genotype 86/86 (r = ?0.34, p = 0.09). These data were completed with an analysis of the BclI polymorphism of the glucocorticoid receptor (GR) gene. There was an association between this GR polymorphism and both awakening salivary cortisol and postdexamethasone salivary cortisol but no association for obesity or metabolic parameters. We concluded that CBG gene polymorphisms might modulate the influence of the HPA axis on the fat mass distribution in this population.  相似文献   
56.

Background

Dendritic cells (DCs) are considered as key mediators of the early events in human immunodeficiency virus type 1 (HIV-1) infection at mucosal sites. Previous studies have shown that surface-bound virions and/or internalized viruses found in endocytic vacuoles of DCs are efficiently transferred to CD4+ T cells. Extracellular adenosine triphosphate (ATP) either secreted or released from necrotic cells induces a distorted maturation of DCs, transiently increases their endocytic capacity and affects their migratory capacity. Knowing that high extracellular ATP concentrations are present in situations of tissue injury and inflammation, we investigated the effect of ATP on HIV-1 transmission from DCs to CD4+ T lymphocytes.

Results

In this study, we show that extracellular ATP reduces HIV-1 transfer from immature monocyte-derived DCs (iDCs) to autologous CD4+ T cells. This observed decrease in viral replication was related to a lower proportion of infected CD4+ T cells following transfer, and was seen with both X4- and R5-tropic isolates of HIV-1. Extracellular ATP had no effect on direct CD4+ T cell infection as well as on productive HIV-1 infection of iDCs. These observations indicate that extracellular ATP affects HIV-1 infection of CD4+ T cells in trans with no effect on de novo virus production by iDCs. Additional experiments suggest that extracellular ATP might modulate the trafficking pathway of internalized virions within iDCs leading to an increased lysosomal degradation, which could be partly responsible for the decreased HIV-1 transmission.

Conclusion

These results suggest that extracellular ATP can act as a factor controlling HIV-1 propagation.
  相似文献   
57.
为探讨在观赏池塘中的投放浮游动物以及直接投放动物粪便对锦鲤(Cyprinus carpio L.)的生长及产量的影响,在池塘中进行了为期11周的实验.实验按如下四种管理系统进行处理:1.给幼体锦鲤投喂浮游动物饲料(LF组);2.直接投放家禽粪便(PM组);3.直接投放牛粪(CD组);4.不投放任何食物,仅进行常规管理(C组).每组实验重复三次.同时检测非自养细菌及致病微生物(如:Aeromonas sp.和Pseudomonas sp.)的生长状况,以此了解池塘的管理状况.在LF组中,其水体含氧量较高,与其它组相比具显著差异(P<0.05).而PM、CD组与LF、C组比较,在PO4-P,NH4-N,NO3-N,NO2-N的关系,导电率、碱度以及生化需氧量等较高,且差异显著(P<0.05),在池塘底部淤泥中的总氮量及有机碳百分率方面PM、CD与LF组相比,具有显著差异(P<0.05).PM与CD组与其它组相比在池塘中的非自养细菌(Aeromonas sp.和Pseudomonas sp.)的繁殖率较高,皆具显著差异P<0.05).LF组中锦鲤的体重增长率较其它组高(P<0.05).锦鲤幼体在C及LF组中的成活率分别为:67.21%和90.11%.结果提示:提高锦鲤幼体的存活率及其产量可通过对水质的管理(即保持优良水质)及提高池塘中浮游生物丰富度加以获得.值得注意的是:LF组中非自养细菌(Aeromonas sp.与Pseudomonas sp.)比率的过低将导致细菌性疾病的发生.  相似文献   
58.
UDP-galactose 4-epimerase from yeast (Kluyveromyces fragilis) is a homodimer of total molecular mass 150 kDa having possibly one mole of NAD/dimer acting as a cofactor. The molecule could be dissociated and denatured by 8 M urea at pH 7.0 and could be functionally reconstituted after dilution with buffer having extraneous NAD. The unfolded and refolded equilibrium intermediates of the enzyme between 0-8 M urea have been characterized in terms of catalytic activity, NADH like characteristic coenzyme fluorescence, interaction with extrinsic fluorescence probe 1-anilino 8-naphthelene sulphonic acid (ANS), far UV circular dichroism spectra, fluorescence emission spectra of aromatic residues and subunit dissociation. While denaturation monitored by parameters associated with active site region e.g. inactivation and coenzyme fluorescence, were found to be cooperative having delta G between -8.8 to -4.4 kcals/mole, the overall denaturation process in terms of secondary and tertiary structure was however continuous without having a transition point. At 3 M urea a stable dimeric apoenzyme was formed having 65% of native secondary structure which was dissociated to monomer at 6 M urea with 12% of the said structure. The unfolding and refolding pathways involved identical structures except near the final stage of refolding where catalytic activity reappeared.  相似文献   
59.
In the pulmonary vasculature, the mechanisms responsible for oxygen sensing and the initiation of hypoxia-induced vasoconstriction and vascular remodeling are still unclear. Nitric oxide (NO) and reactive oxygen species (ROS) are discussed as early mediators of the hypoxic response. Here, we describe a quantitative analysis of NO- and ROS-producing cells within the vascular walls of murine lung sections cultured at normoxia or hypoxia. Whereas the number of NO-producing cells was not changed by hypoxia, the number of ROS-generating cells was significantly increased. Addition of specific inhibitors revealed that mitochondria were the source of ROS. The participation of the individual mitochondrial complexes differed in normoxic and hypoxic ROS generation. Whereas normoxic ROS production required complexes I and III, hypoxic ROS generation additionally demanded complex II. Histochemically demonstrable succinate dehydrogenase activity of complex II in the arterial wall decreased during hypoxia. Inhibition of the reversed enzymatic reaction, i.e., fumarate reductase, by application of succinate, specifically abolished hypoxic, but not normoxic, ROS generation. Thus complex II plays an essential role in hypoxic ROS production. Presumably, its catalytic activity switches from succinate dehydrogenase to fumarate reductase at reduced oxygen tension, thereby modulating the directionality of the electron flow.  相似文献   
60.
Mosbah  H.  Donadille  B.  Vatier  C.  Janmaat  S.  Atlan  M.  Badens  C.  Barat  P.  B&#;liard  S.  Beltrand  J.  Ben Yaou  R.  Bismuth  E.  Boccara  F.  Cariou  B.  Chaouat  M.  Charriot  G.  Christin-Maitre  S.  De Kerdanet  M.  Delemer  B.  Disse  E.  Dubois  N.  Eymard  B.  F&#;ve  B.  Lascols  O.  Mathurin  P.  Nob&#;court  E.  Poujol-Robert  A.  Prevost  G.  Richard  P.  Sellam  J.  Tauveron  I.  Treboz  D.  Verg&#;s  B.  Vermot-Desroches  V.  Wahbi  K.  J&#;ru  I.  Vantyghem  M. C.  Vigouroux  C. 《Orphanet journal of rare diseases》2022,17(1):1-21

Phenylketonuria (PKU) is an inherited metabolic disease characterized by a defective conversion of phenylalanine (Phe) to tyrosine, potentially leading to Phe accumulation in the brain. Dietary restriction since birth has led to normal cognitive development. However, PKU patients can still develop cognitive or behavioral abnormalities and subtle neurological deficits. Despite the increasing evidence in the field, the assessment of neurocognitive, psychopathological, and neurological follow-up of PKU patients at different ages is still debated. The high interindividual variability in the cognitive outcome of PKU patients makes the specificity of the neurocognitive and behavioral assessment extremely challenging. In the present paper, a multidisciplinary panel of Italian PKU experts discussed different tools available for cognitive, psychopathological, and neurological assessment at different ages based on the existing literature and daily clinical practice. This study aims to provide evidence and a real-life-based framework for a specific clinical assessment of pediatric, adolescent, and adult patients affected by PKU.

  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