全文获取类型
收费全文 | 671篇 |
免费 | 59篇 |
出版年
2023年 | 4篇 |
2022年 | 8篇 |
2021年 | 14篇 |
2020年 | 9篇 |
2019年 | 11篇 |
2018年 | 15篇 |
2017年 | 18篇 |
2016年 | 19篇 |
2015年 | 38篇 |
2014年 | 48篇 |
2013年 | 37篇 |
2012年 | 41篇 |
2011年 | 47篇 |
2010年 | 36篇 |
2009年 | 25篇 |
2008年 | 33篇 |
2007年 | 26篇 |
2006年 | 26篇 |
2005年 | 18篇 |
2004年 | 19篇 |
2003年 | 20篇 |
2002年 | 23篇 |
2001年 | 19篇 |
2000年 | 20篇 |
1999年 | 17篇 |
1998年 | 8篇 |
1997年 | 9篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1993年 | 6篇 |
1992年 | 8篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1978年 | 3篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1968年 | 5篇 |
1967年 | 2篇 |
1966年 | 4篇 |
1965年 | 2篇 |
排序方式: 共有730条查询结果,搜索用时 31 毫秒
171.
Correlation between CAG Repeat Length and Clinical Features in Machado-Joseph Disease 总被引:19,自引:3,他引:16
下载免费PDF全文
![点击此处可从《American journal of human genetics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Patrícia Maciel Claudia Gaspar Anita L. DeStefano Isabel Silveira Paula Coutinho Joo Radvany David M. Dawson Lewis Sudarsky Joo Guimares Jose E. L. Loureiro Marjan M. Nezarati Lee I. Corwin Iscia Lopes-Cendes Karen Rooke Roger Rosenberg Patrick MacLeod Lindsay A. Farrer Jorge Sequeiros Guy A. Rouleau 《American journal of human genetics》1995,57(1):54-61
Machado-Joseph disease (MJD) is associated with the expansion of a CAG trinucleotide repeat in a novel gene on 14q32.1. We confirmed the presence of this expansion in 156 MJD patients from 33 families of different geographic origins: 15 Portuguese Azorean, 2 Brazilian, and 16 North American of Portuguese Azorean descent. Normal chromosomes contain between 12 and 37 CAG repeats in the MJD gene, whereas MJD gene carriers have alleles within the expanded range of 62–84 CAG units. The distribution of expanded alleles and the gap between normal and expanded allele sizes is either inconsistent with a premutation hypothesis or most (if not all) of the alleles we studied descend from a common ancestor. There is a strong correlation between the expanded repeat size and the age at onset of the disease as well as the clinical presentation. There is mild instability of the CAG tract length with transmission of the expanded alleles; both increase and decrease in size between parents and progeny occur, with larger variations in male than in female transmissions. Together, these effects can partly explain the variability of age at onset and of phenotypic features in MJD; however, other modifying factors must exist. 相似文献
172.
Self-association of the polyene antibiotic nystatin in dipalmitoylphosphatidylcholine vesicles: a time-resolved fluorescence study.
下载免费PDF全文
![点击此处可从《Biophysical journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The interaction between Nystatin and small unilamellar vesicles of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, both in gel (T = 21 degrees C) and in liquid-crystalline (T = 45 degrees C) phases, was studied by steady-state and time-resolved fluorescence measurements by taking advantage of the intrinsic tetraene fluorophore present in this antibiotic. It was shown that Nystatin aggregates in aqueous solution with a critical concentration of 3 microM. The enhancement in the fluorescence intensity of the antibiotic was applied to study the membrane binding of Nystatin, and it was shown that the antibiotic had an almost fivefold higher partition coefficient for the vesicles in a gel (P = (1.4 +/- 0.1) x 10(3)) than in a liquid-crystalline phase (P = (2.9 +/- 0.1) x 10(2)). Moreover, a time-resolved fluorescence study was used to examine Nystatin aggregation in the membrane. The emission decay kinetics of Nystatin was described by three and two exponentials in the lipid membrane at 21 degrees C and 45 degrees C, respectively. Nystatin mean fluorescence lifetime is concentration-dependent in gel phase lipids, increasing steeply from 11 to 33 ns at an antibiotic concentration of 5-6 microM, but the fluorescence decay parameters of Nystatin were unvarying with the antibiotic concentration in fluid lipids. These results provide evidence for the formation of strongly fluorescent antibiotic aggregates in gel-phase membrane, an interpretation that is at variance with a previous study. However, no antibiotic self-association was detected in a liquid-crystalline lipid bilayer within the antibiotic concentration range studied (0-14 microM). 相似文献
173.
The tachykinins are a family of gastrointestinal peptides comprising eight members: substance P, neurokinin A, neurokinin
B, eledoisin, physalemin, uperolein, kassinin and phyllomedusin. Consensus dynamics was carried out on an
ensemble
of seven tachykinins to determine the binding conformation of the common C-terminal fragment: Phe-X-Gly-Leu-Met-NH
2
,the ’message sequence’ of tachykinins. Three binding modes for the C-terminal pentapeptide were determined. The first binding
conformation is folded due to an intramolecular H-bond between the NH of the variable residue (X) and CO of Met. Other features
include γ-bends at both the variable amino acid (X) and at Gly. The global minimum of the simulation has this conformation
for the C-terminal pentapeptide. The other two binding modes have slightly higher energies. The second is chiefly characterized
by a β-turn around the segment X-Gly-Leu-Met, with additional β-bends at the variable amino acid (X) and Met. The final binding
conformation is composed of β-bends around the variable amino acid (X) and Leu, and a ’pseudo’ γ-bend at the terminal Met.
This paper was presented at the MBU Silver Jubilee Symposium on Structural Biology and 24th Annual Meeting of the Indian Biophysical
Society held at Indian Institute of Science, Bangalore, Dec. 9–12, 1996. 相似文献
174.
Eucalyptus spp. are being propagated extensively as exotics in plantations in South Africa, and many other parts of the world. In South Africa, a number of diseases result in serious losses to this resource. This paper describes a new and very damaging stem canker disease, which has recently appeared on plantation-grown eucalyptus in South Africa. The disease, first noted in an isolated location in Zululand is now common in other parts of the country, and is typified by discrete necrotic lesions on stems. These lesions coalesce to form large, gum-impregnated cankers and malformed stems. The causal agent of the disease, as inferred from pathogenicity tests, is a new species of Coniothyrium described here as C. zuluense. This fungus is a serious impediment to eucalypt propagation in South Africa, and is most likely a threat to similar forest industries elsewhere in the world. 相似文献
175.
Comparisons of the molecular evolutionary process at rbcL and ndhF in the grass family (Poaceae) 总被引:2,自引:1,他引:1
We examine rate heterogeneity among evolutionary lineages of the grass
family at two plasmid loci, ndhF and rbcL, and we introduce a method to
determine whether patterns of rate heterogeneity are correlated between
loci. We show both that rates of synonymous evolution are heterogeneous
among grass lineages and that are heterogeneity is correlated between loci
at synonymous sites. At nonsynonymous sites, the pattern of rate
heterogeneity is not correlated between loci, primarily due to an aberrant
pattern of rate heterogeneity at nonsynonymous sites of rbcL. We compare
patterns of synonymous rate heterogeneity to predictors based on the
generation time effect and the speciation rate hypotheses. Although there
is some evidence for generation time effects, neither generation time
effects nor speciation rates appear to be sufficient to explain patterns of
rate heterogeneity in the grass plastid sequences.
相似文献
176.
177.
The diurnal variability of photosynthesis vs. irradiance (P-I) curves was evaluated for the six most dominant species of macroalgae that occur annually in North Inlet Estuary, South Carolina. Three existing models best simulated the observed data: (1) the Hyperbolic Tangent Model of Jassby and Platt (1976), which was applied to data that showed no photoinhibition; (2) the Exponential Inhibition Model of Parker (1974); and (3) the Photoinhibition Model of Platt et al. (1980), which were employed when photo-inhibition was measured. Photoinhibition was observed in about 75% of the experiments, and in some cases at irradiance levels as low as 500 μE.m?2. s?1. Most of the resulting P-I curves did not differ significantly when measured at various times of the day. As a consequence of these results, we question conclusions expressed by others that it is not possible to accurately determine diurnal photosynthesis of macroalgae from light saturation curves that are measured over short time periods. 相似文献
178.
179.
180.
Suppression of polyclonal antibody production in Trypanosoma cruzi-infected mice by treatment with anti-L3T4 antibodies 总被引:7,自引:0,他引:7
P Minoprio H Eisen M Joskowicz P Pereira A Coutinho 《Journal of immunology (Baltimore, Md. : 1950)》1987,139(2):545-550
Acute Trypanosoma cruzi infection of mice results in a very marked polyclonal activation of B and T lymphocytes, accompanied by high numbers of Ig-secreting PFC and lectin-dependent effector CTL. Treatment of mice with monoclonal anti-L3T4 antibodies from the time of infection (days 0, 4, and 8) completely suppresses the polyclonal PFC response and CTL generation. Treatment of nude mice with antibody does not alter the lipopolysaccharide-induced polyclonal PFC response, and it only modulates the isotypic profile of the PFC response to T. cruzi infection, without reducing its magnitude. Furthermore, antibody-treated, T. cruzi-infected euthymic mice do not develop the typical B cell blastogenic response, but show high numbers of activated Lyt-2+ lymphoblasts in the spleen. These results indicate that effector cell generation in T. cruzi-infected mice is predominantly helper T cell-dependent. 相似文献