全文获取类型
收费全文 | 178篇 |
免费 | 18篇 |
专业分类
196篇 |
出版年
2021年 | 2篇 |
2016年 | 2篇 |
2015年 | 2篇 |
2014年 | 5篇 |
2013年 | 2篇 |
2012年 | 5篇 |
2011年 | 12篇 |
2010年 | 2篇 |
2009年 | 3篇 |
2008年 | 12篇 |
2007年 | 14篇 |
2006年 | 4篇 |
2005年 | 8篇 |
2004年 | 5篇 |
2003年 | 7篇 |
2002年 | 7篇 |
2001年 | 6篇 |
2000年 | 11篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有196条查询结果,搜索用时 78 毫秒
31.
32.
Background
We aimed to evaluate the incidence of type 1 diabetes mellitus in children <15 years of age (yr) in the Auckland region (New Zealand) over 20 years (1990–2009).Methods
We performed a retrospective review of all patients <15 yr diagnosed with type 1 diabetes, from an unselected complete regional cohort.Results
There were 884 new cases of type 1 diabetes, and age at diagnosis rose from 7.6 yr in 1990/1 to 8.9 yr in 2008/9 (r2 = 0.31, p = 0.009). There was a progressive increase in type 1 diabetes incidence among children <15 yr (p<0.0001), reaching 22.5 per 100,000 in 2009. However, the rise in incidence did not occur evenly among age groups, being 2.5-fold higher in older children (10–14 yr) than in the youngest group (0–4 yr). The incidence of new cases of type 1 diabetes was highest in New Zealand Europeans throughout the study period in all age groups (p<0.0001), but the rate of increase was similar in New Zealand Europeans and Non-Europeans. Type 1 diabetes incidence and average annual increase were similar in both sexes. There was no change in BMI SDS shortly after diagnosis, and no association between BMI SDS and age at diagnosis.Conclusions
There has been a steady increase in type 1 diabetes incidence among children <15 yr in Auckland over 20 years. Contrary to other studies, age at diagnosis has increased and the greatest rise in incidence occurred in children 10–14 yr. There was little change in BMI SDS in this population, providing no support for the ‘accelerator hypothesis’. 相似文献33.
Alimonti J Zhang QJ Gabathuler R Reid G Chen SS Jefferies WA 《Nature biotechnology》2000,18(5):515-520
A major class of tumors lack expression of the transporters associated with antigen processing (TAP). These proteins are essential for delivery of antigenic peptides into the lumen of the endoplasmic reticulum (ER) and subsequent assembly with nascent major histocompatibility complex (MHC) class I, which results in cell surface presentation of the trimeric complex to cytolytic T lymphocytes. Cytolytic T lymphocytes are major effector cells in immunosurveillance against tumors. Here we have tested the hypothesis that TAP downregulation in tumors allows immunosubversion of this effector mechanism, by establishing a model system to examine the role of TAP in vivo in restoring antigen presentation, immune recognition, and effects on malignancy of the TAP-deficient small-cell lung carcinoma, CMT.64. To test the potential of providing exogenous TAP in cancer therapies, we constructed a vaccinia virus (VV) containing the TAP1 gene and examined whether VV-TAP1 could reduce tumors in mice. The results demonstrate that TAP should be considered for inclusion in cancer therapies, as it is likely to provide a general method for increasing immune responses against tumors regardless of the antigenic complement of the tumor or the MHC haplotypes of the host. 相似文献
34.
35.
This paper describes a global investigation of the components of Fasciola hepatica excretory-secretory (ES) products by a proteomic approach. Despite the absence of a F. hepatica genome sequencing project we have shown that it was possible to identify 29 of the 60 prominent proteins found using two-dimensional gel electrophoresis. As well as cathepsin L proteases, a number of enzymes implicated in parasite protection from the host immune system were also found to be present in relatively large abundance. These included superoxide dismutase, thioredoxin peroxidase, glutathione S-transferases and fatty acid binding proteins, all of which may play a part in the detoxification of reactive oxygen intermediates. Interestingly, ovine superoxide dismutase was the only protein from the host identified on the gel. We suggest that the relative abundance and protective nature of the components of the ES products of this organism play an important role in its survival within the host. The precise identification, to individual NCBI database entries, of a number of glutathione S-transferases and cathepsin Ls from F. hepatica, by peptide mass fingerprinting, was hampered by multi-database submissions of the two protein superfamilies from this organism. 相似文献
36.
Background
Type 1 diabetes mellitus (T1DM) may lead to severe long-term health consequences. In a longitudinal study, we aimed to identify factors present at diagnosis and 6 months later that were associated with glycosylated haemoglobin (HbA1c) levels at 24 months after T1DM diagnosis, so that diabetic children at risk of poor glycaemic control may be identified.Methods
229 children <15 years of age diagnosed with T1DM in the Auckland region were studied. Data collected at diagnosis were: age, sex, weight, height, ethnicity, family living arrangement, socio-economic status (SES), T1DM antibody titre, venous pH and bicarbonate. At 6 and 24 months after diagnosis we collected data on weight, height, HbA1c level, and insulin dose.Results
Factors at diagnosis that were associated with higher HbA1c levels at 6 months: female sex (p<0.05), lower SES (p<0.01), non-European ethnicity (p<0.01) and younger age (p<0.05). At 24 months, higher HbA1c was associated with lower SES (p<0.001), Pacific Island ethnicity (p<0.001), not living with both biological parents (p<0.05), and greater BMI SDS (p<0.05). A regression equation to predict HbA1c at 24 months was consequently developed.Conclusions
Deterioration in glycaemic control shortly after diagnosis in diabetic children is particularly marked in Pacific Island children and in those not living with both biological parents. Clinicians need to be aware of factors associated with poor glycaemic control beyond the remission phase, so that more effective measures can be implemented shortly after diagnosis to prevent deterioration in diabetes control. 相似文献37.
Abstract Left–right asymmetry in Dexiothetica (= echinoderms + chordates) results mainly from dexiothetism—an episode in their ancestry when an animal resembling the Recent pterobranch Cephalodiscus lay right-side-downwards on the sea floor. Castericystis sprinklei belongs to the dexiothete stem group. The history of the echinoderm stem group is reconstructed. Chordate bilateral symmetry evolved by six successive steps. Tail–head overlap occurred independently in craniates and acraniates. The neural crest would have existed in the latest common ancestor of extant chordates, or even earlier. Gross asymmetries occur in extant chordates in organs derived from the calcichordate head, but not in those derived from the calcichordate tail. The anterior boundary of hox gene expression in vertebrates corresponds to the anterior end of the calcichordate tail. Left–right organ pairing (an important step in the origin of chordate bilateral symmetry) may have involved the interaction of a symmetrizing morphogen, produced from the anterior end of the tail, with a lateral morphogen (Wilhelmi's morphogen), produced in ontogeny at first from the left and later from the right. This mechanism may still act in the metamorphosis of amphioxus and in mirror-imaging in vertebrate twins. Wilhelmi's morphogen may be related to one or more members of the dorsal cascade of Drosophila. 相似文献
38.
39.
The conversion of ent-kaur-16-enes to gibberellic acid in Gibberella fujikuroi is blocked by A-ring modifications. Thus ent-3β-hydroxykaur-16-en-19-yl succinate gives good conversion (46%) to the 7β-hydroxy derivative.* Under the same conditions the 3β-epimer gives 7β- or 6α-hydroxylation and the former occurs for the 3-oxo analogue. The succinoyloxy function acts as a less efficient block and ent-kaur-16-en-19-yl succinate is converted to 7β-hydroxy and 6β,7β-dihydroxy derivatives along with gibberellic acid. Hydrolysis of the succinate block of the metabolities provides the 7β, 19-diol and 6β,7β, 19-triol. Of this pair only the former was effectively metabolized to gibberellic acid in G. fujikuroi. 相似文献
40.
The amino acid sequence of cytochrome c from Helix aspersa Müller (garden snail) 总被引:3,自引:3,他引:0 下载免费PDF全文
R. H. Brown M. Richardson D. Boulter J. A. M. Ramshaw R. P. S. Jefferies 《The Biochemical journal》1972,128(4):971-974
The amino acid sequence of a snail cytochrome c has been determined. The molecule consists of a single polypeptide chain of 104 residues, and is homologous with other mitochondrial cytochromes c. Unlike the cytochromes c from vertebrates, there is no acetyl blocking group at the N-terminus. A change in an otherwise invariant position has been observed in position 87. Comparison with amino acid sequences of cytochromes c from other sources indicates that the point of divergence of the molluscs and the vertebrates in evolutionary time was 720 million years ago. Experimental details are given in a supplementary paper that has been deposited as Supplementary Publication SUP 50009 at the National Lending Library for Science and Technology, Boston Spa, Yorks. LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1972), 126, 5. 相似文献