全文获取类型
收费全文 | 207篇 |
免费 | 32篇 |
国内免费 | 1篇 |
出版年
2021年 | 2篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2015年 | 7篇 |
2014年 | 6篇 |
2013年 | 11篇 |
2012年 | 12篇 |
2011年 | 8篇 |
2010年 | 11篇 |
2009年 | 14篇 |
2008年 | 5篇 |
2007年 | 7篇 |
2006年 | 7篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 10篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 10篇 |
1984年 | 5篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1969年 | 2篇 |
1947年 | 2篇 |
1924年 | 2篇 |
1922年 | 1篇 |
1919年 | 1篇 |
1916年 | 1篇 |
1914年 | 1篇 |
1913年 | 1篇 |
1909年 | 1篇 |
1897年 | 1篇 |
1892年 | 1篇 |
1889年 | 4篇 |
1887年 | 3篇 |
1875年 | 1篇 |
排序方式: 共有240条查询结果,搜索用时 15 毫秒
1.
2.
Segregation of all four major fibrillar collagen genes in the Marfan syndrome. 总被引:12,自引:4,他引:8
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)
D J Ogilvie B P Wordsworth L M Priestley R Dalgleish J Schmidtke B Zoll B C Sykes 《American journal of human genetics》1987,41(6):1071-1082
Linkage markers at or close to the genes encoding the three major fibrillar collagens were used to analyze the segregation of these loci in six pedigrees with dominantly inherited Marfan syndrome. Four pedigrees were discordant at one of the Type I collagen loci (COL1A2), and, of these, two were discordant at the other Type I locus (COL1A1). The Marfan syndrome also segregated independently of the structural loci for Type II and Type III collagen in these two families. This is evidence against the Marfan syndrome being, in general, due to mutations in the major fibrillar collagen genes. 相似文献
3.
We have isolated the delta-globin gene of the New-World spider monkey,
Ateles geoffroyi, and compared its nucleotide sequence with those of other
primate delta- and beta-globin genes. Among primate delta-globin genes, the
rate of nonsynonymous substitutions is much less than the rate of
synonymous substitutions. This suggests that primate delta- globin genes
may remain under evolutionary conservation, perhaps because hemoglobin A2
has an as yet unknown physiological importance.
相似文献
4.
J. V. Priestley M. A. Hynes V. K. M. Han M. Réthelyi E. R. Perl P. K. Lund 《Histochemistry and cell biology》1988,89(5):467-479
Summary Methodological variables for in situ hybridization using 32P labelled oligodeoxyribonucleotides (oligomers) have been examined. Four different oligomers directed against proglucagon messenger RNA (mRNA) and two different oligomers against prosomatostatin mRNA have been used. Specific hybridization was obtained in adult rat brain, stomach and pancreas and in neonatal rat ileum. Tissue was perfusion fixed with 4% paraformaldehyde 0.2% glutaraldehyde and hybridization was carried out in 50% formamide for 72 h at 42° C. Using hybridization conditions of lower stringency (33% formamide) labelling was also obtained in guinea pig tissue. Other variables which affected hybridization signal intensity were the inclusion of a prehybridization dehydration stage, the probe concentration, the inclusion of ammonium acetate in the posthybridization dehydrating ethanols and in the autoradiographic emulsion, and the exposure time. The localisation of proglucagon mRNA in rat pancreas using a 20mer was used as a model tissue for testing these methodological variables and the results were found generally also to apply to the other probes and tissues tested. The methods described provide single cell resolution and show that 32P labelled oligomers may be used to localise neuropeptide and endocrine mRNAs in different types of tissue and in different mammalian species. 相似文献
5.
S R Seidner A H Jobe M Ikegami A Pettenazzo A Priestley L Ruffini 《Biochimica et biophysica acta》1988,961(3):328-336
Tracer quantities of 3H-labeled lysoPC and 32P-labeled natural rabbit surfactant were given intratracheally via a bronchoscope and [14C]palmitate was given intravenously to 25 rabbits with labeled PC and lysoPC measured in the alveolar wash, lung homogenate, lamellar bodies and microsomes at five times from 10 min to 6 h after tracheal injection. Surprisingly, only 31% of the administered lysoPC remained in its original form in the total lungs (alveolar wash + lung homogenate) by 10 min, of which 77% was in the alveolar wash. Meanwhile, by 10 min an additional 37% was already converted to PC, of which more than 98% was in the lung homogenate. LysoPC continued to be rapidly and efficiently converted to PC, with 62% conversion measured at 3 h. The converted lysoPC initially appeared with high specific activity in microsomes, then in lamellar bodies, and finally in the alveolar wash. The intravascular palmitate labeled lung PC had similar specific activity-time profiles in the subcellular fractions, while intratracheally administered natural rabbit surfactant had a constantly low specific activity in microsomes and much higher specific activities in lamellar bodies and alveolar wash. Another 25 rabbits received intratracheal lysoPC labeled in both the choline and palmitate moieties and then were studied from 1 to 24 h after tracheal injection. The ratio of the palmitate to choline labels indicated uptake and conversion to PC primarily by direct acylation rather than transacylation and by intact reuptake and conversion rather than breakdown and resynthesis. LysoPC is an attractive 'metabolic probe' of surfactant metabolism which undergoes very rapid and efficient intracellular conversion to PC via a subcellular pathway that parallels the remodeling and de novo synthetic pathways. 相似文献
6.
David A. Priestley Brenda G. Werner A. Carl Leopold Murray B. McBride 《Physiologia plantarum》1985,64(1):88-94
In view of their possible role in oxidative deterioration of seeds and pollen, organic free radicals were measured by electron spin resonance in embryonic axes and cotyledons of soybean [ Glycine max (L.) Merr], embryo and endosperm fractions of corn [ Zea mays L.] and pollen of cattail [ Typha latifolia L.]. A pronounced decline in the radical signal ensued when hydration increased above about 7% (wet weight basis) in both the seed materials and in pollen. Moderate hydration of the soybean axis followed by drying led to a small decrease in organic free radicals compared to untreated material, especially if the desiccation step was performed under nitrogen. In a comparison of soybeans of various ages under normal storage, organic free radical levels in the axis showed little or no increase with age. In marked contrast, over 5 days of accelerated aging at 40°C and near-saturating humidity, organic radical levels approximately doubled in the axis. This pronounced increase in free radical content was not associated with a decrease in the proportion of polyunsaturated fatty acids. The data suggest that hydration of seed and pollen causes a release of free radicals from the trapped state. 相似文献
7.
Biochemical pathways in prokaryotes can be traced backward through evolutionary time 总被引:10,自引:0,他引:10
For the first time, a credible prokaryotic phylogenetic tree is being
assembled by Woese and others using quantitative sequence analysis of
oligonucleotides in the highly conservative rRNA. This provides an
evolutionary scale against which the evolutionary steps that led to the
arrangement and regulation of contemporary biochemical pathways can be
measured. This paper presents an emerging evolutionary picture of aromatic
amino acid biosynthesis within a large superfamily assemblage of
prokaryotes that is sufficiently developed to illustrate a new perspective
that will be applicable to many other biochemical pathways.
相似文献
8.
Whole amyloplasts were isolated from Zea mays L. coleoptiles. Electron microscopy confirmed that their envelopes consisted of two intact membranes. Their surface charge was quantified through electrokinetic measurements employing a vertically oriented cataphoresis cell. Amyloplasts from coleoptiles of different ages (5–9 d) and degree of exposure to light (0–9 d) all had negative zeta potentials (mean of -19.4 mV). Isolated starch granules had comparable values. The net negative surface charge was confirmed ultrastructurally by the binding of cationised ferritin to both amyloplasts and starch grains. Cationised ferritin tagged with a fluorescent label (fluorescein isothiocyanate) showed binding to some amyloplasts but not to starch grains. These results are discussed in the context of a hypothesized role for statolith charge in plant graviperception. 相似文献
9.
In Drosophila pseudoobscura, the amylase (Amy) multigene family is
contained within a series of inversions, or gene arrangements, on the third
chromosome. The Standard (ST), Santa Cruz (SC), and Tree Line (TL)
inversions are central to the phylogeny of arrangements, and have clusters
of other arrangements derived from them. The gene arrangements belonging to
each of these three clusters have a characteristic number of Amy genes,
ranging from three in ST to two in SC to one in TL. This distribution
pattern can reflect a history of either duplications or deletions, although
the data available in the past did not permit a decision between these
alternatives. We provide unambiguous evidence that three Amy genes were
present before the divergence of the ST, SC, and TL arrangements. Thus, the
current status of the Amy multigene family is the result of deletions in
the TL and SC arrangements, which created three new pseudogenes: TL
Amy2-psi, TL Amy3-psi, and SC Amy3- psi. Analysis of pseudogene sequences
revealed that, in the SC and ST arrangements, pseudogene evolution has been
retarded, most likely due to the homogenization effect of gene conversion.
Finally, by determining the original copy number, we have reconstructed the
evolutionary history of the Amy multigene family and linked it with the
evolution of the central gene arrangements.
相似文献
10.
The application of sensory methodology for measuring deodorizing effect of an air conditioner equipped with electric plasma was introduced. Deodorizing effect was measured using chemical and sensory methods at different time (0, 30 and 60 min) and mode (control, blowing and cooling) of an air conditioner. Smoke from a roll of cigarette in a closed room was used as a source of odor and the concentrations of acetic acid and ammonia were measured as odorous chemical components. As one of the sensory methods triangle test was used and as a first step to obtain deodorizing effects by triangle test, the threshold of each panelist was obtained as the log dilution ratio of odor concentration at which the difference from odorless air was detected. The odor concentration at each time and mode was calculated using the threshold of the panel and the deodorizing effect was obtained on the basis of the odor concentration. In addition to a triangle test, scaling methods such as category scaling or magnitude estimation were used to measure deodorizing effect of an air conditioner. Deodorizing effects by scaling methods were calculated based on odor intensity with time at each mode. The regression analysis was done between the efficacy of deodorizing effect by sensory test and those by acetic acid and ammonia, the R2 values of the regression equations for triangle test, category scale, and magnitude estimation were 0.84, 0.72 and 0.69, respectively. Deodorizing effect by triangle test explained the decrease of acetic acid and ammonia better than those by category scaling or magnitude estimation while high cost and time consuming labor involved in triangle tests reduced the merit. The results of this study demonstrated that various sensory methods could be used to measure deodorizing effect of air conditioners and further researches on fast and reliable methods are needed to establish the official procedures. 相似文献