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   572篇
  免费   8篇
  国内免费   1篇
  2021年   6篇
  2020年   10篇
  2019年   7篇
  2018年   10篇
  2017年   12篇
  2016年   13篇
  2015年   9篇
  2014年   17篇
  2013年   22篇
  2012年   24篇
  2011年   24篇
  2010年   19篇
  2009年   16篇
  2008年   23篇
  2007年   28篇
  2006年   17篇
  2005年   11篇
  2004年   9篇
  2003年   17篇
  2002年   12篇
  2001年   11篇
  2000年   22篇
  1999年   17篇
  1993年   5篇
  1992年   10篇
  1991年   14篇
  1990年   11篇
  1989年   8篇
  1988年   10篇
  1987年   9篇
  1986年   6篇
  1985年   5篇
  1984年   4篇
  1983年   16篇
  1982年   4篇
  1980年   4篇
  1979年   15篇
  1978年   7篇
  1976年   5篇
  1975年   6篇
  1974年   10篇
  1973年   9篇
  1972年   5篇
  1971年   10篇
  1970年   7篇
  1969年   11篇
  1968年   6篇
  1967年   4篇
  1966年   4篇
  1965年   5篇
排序方式: 共有581条查询结果,搜索用时 576 毫秒
71.

Introduction

HLA-B*51 and HLA-B*52 are two close human leukocyte antigen (HLA) allele groups with minor amino acid differences. However, they are associated with two different vasculitides (HLA-B*51 in Behçet's disease and HLA-B*52 in Takayasu's arteritis (TAK)) and with major clinical and immunological differences. In this study, we aimed to screen a large cohort of TAK patients from Turkey for the presence of HLA-B*51 and HLA-B*52 as susceptibility and severity factors.

Methods

TAK patients (n = 330) followed at a total of 15 centers were included in the study. The mean age of the patients was 37.8 years, and 86% were women. DNA samples from the patients and healthy controls (HC; n = 210) were isolated, and the presence of HLA-B*51 or HLA-B*52 was screened for by using PCR with sequence-specific primers.

Results

We found a significant association of HLA-B*52 with TAK (20.9% vs HC = 6.7%, P = 0.000, OR = 3.7, 95% CI = 2.02 to 6.77). The distribution of HLA-B*51 did not differ between TAK patients and HCs (22.7% vs 24.8%, OR = 0.9, 95% CI = 0.60 to 1.34). The presence of HLA-B*52 decreased in late-onset patients (> 40 years of age; 12.0%, P = 0.024, OR = 0.43, 95% CI = 0.20 to 0.91). Patients with angiographic type I disease with limited aortic involvement also had a lower presence of HLA-B*52 compared to those with all other disease subtypes (13.1% vs 26%, P = 0.005, OR = 0.43, 95% CI = 0.23 to 0.78).

Conclusions

In this study, the previously reported association of TAK with HLA-B*52 in other populations was confirmed in patients from Turkey. The functional relevance of HLA-B*52 in TAK pathogenesis needs to be explored further.  相似文献   
72.
Following the initial acute stage of spinal cord injury, a cascade of cellular and inflammatory responses will lead to progressive secondary damage of the nerve tissue surrounding the primary injury site. The degeneration is manifested by loss of neurons and glial cells, demyelination and cyst formation. Injury to the mammalian spinal cord results in nearly complete failure of the severed axons to regenerate. We have previously demonstrated that the antioxidants N-acetyl-cysteine (NAC) and acetyl-L-carnitine (ALC) can attenuate retrograde neuronal degeneration after peripheral nerve and ventral root injury. The present study evaluates the effects of NAC and ALC on neuronal survival, axonal sprouting and glial cell reactions after spinal cord injury in adult rats. Tibial motoneurons in the spinal cord were pre-labeled with fluorescent tracer Fast Blue one week before lumbar L5 hemisection. Continuous intrathecal infusion of NAC (2.4 mg/day) or ALC (0.9 mg/day) was initiated immediately after spinal injury using Alzet 2002 osmotic minipumps. Neuroprotective effects of treatment were assessed by counting surviving motoneurons and by using quantitative immunohistochemistry and Western blotting for neuronal and glial cell markers 4 weeks after hemisection. Spinal cord injury induced significant loss of tibial motoneurons in L4-L6 segments. Neuronal degeneration was associated with decreased immunostaining for microtubular-associated protein-2 (MAP2) in dendritic branches, synaptophysin in presynaptic boutons and neurofilaments in nerve fibers. Immunostaining for the astroglial marker GFAP and microglial marker OX42 was increased. Treatment with NAC and ALC rescued approximately half of the motoneurons destined to die. In addition, antioxidants restored MAP2 and synaptophysin immunoreactivity. However, the perineuronal synaptophysin labeling was not recovered. Although both treatments promoted axonal sprouting, there was no effect on reactive astrocytes. In contrast, the microglial reaction was significantly attenuated. The results indicate a therapeutic potential for NAC and ALC in the early treatment of traumatic spinal cord injury.  相似文献   
73.
In plants, Rab proteins represent the largest family of monomeric GTP-binding proteins (mG-proteins). As distinct from animal cells comprising 40 subfamilies of Rab proteins, which are the key regulators of intracellular vesicular transport, numerous Rab proteins in Arabidopsis and other plant species could be grouped in only eight subfamilies on the basis of their functional properties. The available data concerning the involvement of these mG-proteins in the control of vesicle trafficking agree generally with the paradigms accepted for other eukaryotes. On the other hand, these proteins play an important role in plant responses to abiotic and biotic factors, indicating specific for plants functions of Rab proteins.  相似文献   
74.
Retrotransposons are the major component of plant genomes. Chromodomain-containing Gypsy long terminal repeat (LTR) retrotransposons are widely distributed in eukaryotes. Four distinct clades of chromodomain-containing Gypsy retroelements are known from the vascular plants: Reina, CRM, Galadriel and Tekay. At the same time, almost nothing is known about the repertoire of LTR retrotransposons in bryophyte genomes. We have combined a search of chromodomain-containing Gypsy retroelements in Physcomitrella genomic sequences and an experimental investigation of diverse moss species. The computer-based mining of the chromodomain-containing LTR retrotransposons allowed us to describe four different elements from Physcomitrella. Four novel clades were identified that are evolutionarily distinct from the chromodomain-containing Gypsy LTR retrotransposons of other plants.  相似文献   
75.
It was demonstrated that the fungus Penicillium expansum 2-7, a resident strain of the orbital complex Mir, which became dominant at the end of a long-term space flight, formed biologically active secondary metabolites (antibiotics). Using physicochemical methods these metabolites were identified as xanthocyllin X and questiomycin A. The time courses of their biosyntheses during the growth and development of the producer culture were studied. The addition of zinc to the culture medium affected both the growth of the culture and the biosyntheses of the antibiotics. The concentrations of zinc in the medium, optimum for xanthocyllin X and questiomycin A production, were 0.3 and 3.0 mg/l, respectively.  相似文献   
76.
77.
78.
Prolonged helium-oxygen hyperbaric (pressure 3,6 MPa) increased diene conjugate and Schiff's base level in plasma and erythrocyte membranes of mice. In those conditions SOD and glucose 6-phosphate dehydrogenase activities were inhibited in erythrocytes. Lipid bilayer microviscosity and cholesterol content of erythrocyte membranes were increased.  相似文献   
79.
O-Linked oligosaccharides from N,O-glycoproteins were selectively split off by treatment with alkaline sodium borohydride in the presence of cadmium salt. The side reaction of reductive cleavage of N-glycosylamide and peptide bonds, observed under standard conditions of splitting of O-linked chains (M NaBH4 and 50mM NaOH, 16 h, 50 degrees), was inhibited by addition of 50-10 mM cadium acetate and 5-10mM EDTA.Na4, as shown by treatment of model compounds and several glycoproteins (ovomucoid, group-specific glycoproteins H and B, fetuin, and asialofetuin). This treatment, in combination with the previously developed procedure for the release of the N-linked oligosaccharide chains by lithium borohydride, allows a sequential, selective cleavage of O-, and then N-linked oligosaccharides from N,O-glycoproteins by chemical methods.  相似文献   
80.
The protective properties of the species-specific pore-forming polypeptide of Y. pseudotuberculosis outer membrane (porin) were studied. The study showed that 80-90% of mice immunized with porin survived after challenge with 10-30 LD50 of Y. pseudotuberculosis, serovars 1 and 3. The LD50 of the preparation exceeded its ED50 more than 100-fold. Immunization made in two injections was more effective than immunization in one injection. The immunization of the animals with porin led to an increase in the activity of peritoneal exudate macrophages with respect to Y. pseudotuberculosis, serovars 1 and 3.  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