全文获取类型
收费全文 | 522篇 |
免费 | 80篇 |
出版年
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 8篇 |
2015年 | 14篇 |
2014年 | 10篇 |
2013年 | 15篇 |
2012年 | 14篇 |
2011年 | 12篇 |
2010年 | 7篇 |
2009年 | 15篇 |
2008年 | 17篇 |
2007年 | 17篇 |
2006年 | 11篇 |
2005年 | 15篇 |
2004年 | 12篇 |
2003年 | 22篇 |
2002年 | 26篇 |
2001年 | 18篇 |
2000年 | 36篇 |
1999年 | 23篇 |
1998年 | 16篇 |
1997年 | 11篇 |
1996年 | 9篇 |
1995年 | 16篇 |
1994年 | 5篇 |
1993年 | 8篇 |
1992年 | 14篇 |
1991年 | 15篇 |
1990年 | 23篇 |
1989年 | 8篇 |
1988年 | 10篇 |
1987年 | 14篇 |
1986年 | 6篇 |
1985年 | 12篇 |
1984年 | 14篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1981年 | 8篇 |
1980年 | 16篇 |
1979年 | 6篇 |
1978年 | 13篇 |
1977年 | 9篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1974年 | 4篇 |
1973年 | 4篇 |
1892年 | 2篇 |
排序方式: 共有602条查询结果,搜索用时 15 毫秒
1.
M. J. Schwarz M. Super C. Wallis P. Beighton C. Newton L. E. Heptinstall C. Summers A. Markham G. Hambleton K. W. Webb D. Bilto D. Heaf M. Dalzell 《Human genetics》1990,85(4):428-430
Summary Details of haplotype and ΔF508 status from various populations represented in the cystic fibrosis (CF) DNA bank of the Royal
Manchester Children's Hospital are provided, together with information on the association of genotype and clinical status.
Clinical details and DNA analyses from native English in the North-West and South-West of England (Bath), from Lancashire
Pakistani families and from Afrikaans Namibian families are compared. A 78.5% incidence of ΔF508 has been found in English
families. Compound heterozygotes with CF and only one ΔF508 gene have an increased likelihood of having milder disease, with
lessPseudomonas isolated from sputum and relatively more showing either no regular respiratory pathogens or colonisation withStaphylococcus. There is also a relative increase in meconium ileus in these compound heterozygotes. The diagnosis of CF may be in doubt
in some subjects negative for ΔF508. Some of the Bath families have unusual haplotypes for an English population and a compound
heterozygote ΔF508/ΔI507 has been found. There is evidence from metD analysis of the founder effect in the Afrikaans Namibian
families, who have a high ΔF508 incidence. 相似文献
2.
S-Adenosylmethionine synthetase from Escherichia coli 总被引:16,自引:0,他引:16
G D Markham E W Hafner C W Tabor H Tabor 《The Journal of biological chemistry》1980,255(19):9082-9092
Adenosylmethionine (AdoMet) synthetase has been purified to homogeneity from Escherichia coli. For this purification, a strain of E. coli which was derepressed for AdoMet synthetase and which harbors a plasmid containing the structural gene for AdoMet synthetase was constructed. This strain produces 80-fold more AdoMet synthetase than a wild type E. coli. AdoMet synthetase has a molecular weight of 180,000 and is composed of four identical subunits. In addition to the synthetase reaction, the purified enzyme catalyzes a tripolyphosphatase reaction that is stimulated by AdoMet. Both enzymatic activities require a divalent metal ion and are markedly stimulated by certain monovalent cations. AdoMet synthesis also takes place if adenyl-5'yl imidodiphosphate (AMP-PNP) is substituted for ATP. The imidotriphosphate (PPNP) formed is not hydrolyzed, permitting dissociation of AdoMet formation from tripolyphosphate cleavage. An enzyme complex is formed which contains one equivalent (per subunit) of adenosylmethionine, monovalent cation, imidotriphosphate, and presumably divalent cation(s). The rate of product dissociation from this complex is 3 orders of magnitude slower than the rate of AdoMet formation from ATP. Studies with the phosphorothioate derivatives of ATP (ATP alpha S and ATP beta S) in the presence of Mg2+, Mn2+, or Co2+ indicate that a divalent ion is bound to the nucleotide during the reaction and provide information on the stereochemistry of the metal-nucleotide binding site. 相似文献
3.
The CD spectra of cUpUp, cCpCp, and cGpGp derived from DCC-catalyzed polymerization of the relevant protected ribonucleoside 3′-phosphates are described. Similar studies on Up, U > p, and cUp, as well as cUpUpUp and cUpUpUpUp, are presented. The spectral properties of the cyclic oligomers are compared with those of the corresponding linear oligomers with terminal 3′-phosphates so as to demonstrate that disruption of normal right-handed base stacking is considerable in these RNA loops. 相似文献
4.
The advent of the polymerase chain reaction has stimulated the development of a number of rapid methods for characterizing human genes. In addition, the unprecedented level of sensitivity offered by some of these methods may prove to be of great value in the detection of minority cell populations. Over the past year, technical developments have been made in this area. 相似文献
5.
L M Moynihan S E Bundey D Heath E L Jones D P McHale R F Mueller A F Markham N J Lench 《American journal of human genetics》1998,62(5):1123-1128
We describe a highly consanguineous family, originating from Pakistan, displaying histiocytosis, joint contractures, and sensorineural deafness. The form of histiocytosis exhibited by this family does not fit readily into any of the recognized classes of this disease. It appears to represent a novel form of familial histiocytosis demonstrating autosomal recessive inheritance. Using autozygosity mapping, we have identified a homozygous region of approximately 1 cM at chromosome 11q25, in affected individuals. A maximum two-point LOD score of 3.42 (recombination fraction straight theta = .00) was obtained with marker D11S968. This is the first genetic locus to be described that is involved in the molecular pathogenesis of histiocytosis. 相似文献
6.
A wide variety of novel flavone 5-O-glucosides has been isolated from Lycopodium scariosum. The predominance of tricin derivatives in this species is not in accord with earlier proposed chemotaxonomic definitions of the sub-groups within the classical genus Lycopodium L. cernuum is the first lycopod found to contain flavone C-glycosides and its suggested taxonomic separation from other members of the group is thus substantiated. Flavonoid glycosides appear to offer more definitive chemotaxonomic characters than do the previously used aglycones and modification of the chemical definitions of the sub-groups in these terms is necessary. 相似文献
7.
P.S. Cocks I.S. Fraser R. Markham M. Robinson R.P. Shearman 《Prostaglandins & other lipid mediators》1980,20(3):493-502
Peripheral plasma concentrations of 13, 14-dihydro-15-keto prostaglandin F2α (PGFM) were measured in seven women having elective cervical encerclage in an otherwise normal pregnancy. Three of seven patients had a statistically significant elevation of PGFM levels at 60 minutes after commencement of surgery. On the basis that the majority of patients had no significant rise and that there was no objective evidence of uterine contractions post-operatively, the routine administration of prostaglandin inhibitory agents to patients having cervical encerclage cannot be recommended. 相似文献
8.
Factors Associated with Slow Disease Progression in Macaques Immunized with an Adenovirus-Simian Immunodeficiency Virus (SIV) Envelope Priming-gp120 Boosting Regimen and Challenged Vaginally with SIVmac251 下载免费PDF全文
9.
R B Markham A White A L Goldstein 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1975,148(1):190-193
A steroid, 6-chloro-17-hydroxypregna-1,4,6-triene-3,20-doine (CHP) that exhibits selective activity in several models of cellular immunity including an apparent inhibitory action on the elicitation of delayed hypersensitivity, was examined in a new, simple experimental model for assessing aspects of host-cell-mediated immunological competence. This model is based upon the capacity of the adult mouse to prevent the progressive growth of tumors induced by the Moloney sarcoma virus. Two steroids reported to have immunosuppressive activity in other assay systems, namely, cortisol and progesterone, were also studied. Control mice and those injected with CHP maintained their capacity to reject the tumor. In contrast, significant numbers of mice receiving a single large injection of cortisol or progesterone succumbed to progressive tumor growth under the experimental conditions used. The data indicate that CHP, while influencing selected parameters of cellular immunity, e.g., the elicitation of delayed hypersensitivity, does not decrease the capacity of the host to mount a defense against the progressive growth of the Moloney virus-induced sarcoma. The results indicate that CHP may be useful in modulating specific aspects of cellular immunity without altering others. In addition, the experimental model described provides a simple method of assessing the possible immunosuppressive effects of naturally occurring and synthetic agents on viral-induced tumor growth. 相似文献
10.
The human aldose reductase gene maps to chromosome region 7q35 总被引:1,自引:0,他引:1
Alexander Graham Paul Heath John E. N. Morten Alexander F. Markham 《Human genetics》1991,86(5):509-514
Summary The human aldose reductase (AR) gene has been mapped to chromosome 7 using the polymerase chain reaction to specifically amplify the human AR sequence in hamster/human hybrid DNA and also in mouse/ human monochromosome hybrids. The assignment to chromosome 7 was confirmed by in situ hybridisation to human metaphase chromosomes using a novel, rapid hybridisation, method giving a regional localisation at 7q35. 相似文献