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排序方式: 共有347条查询结果,搜索用时 15 毫秒
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Richard GH Immink Isabella AN Tonaco Stefan de Folter Anna Shchennikova Aalt DJ van Dijk Jacqueline Busscher-Lange Jan W Borst Gerco C Angenent 《Genome biology》2009,10(2):R24-16
Background
Plant MADS box proteins play important roles in a plethora of developmental processes. In order to regulate specific sets of target genes, MADS box proteins dimerize and are thought to assemble into multimeric complexes. In this study a large-scale yeast three-hybrid screen is utilized to provide insight into the higher-order complex formation capacity of the Arabidopsis MADS box family. SEPALLATA3 (SEP3) has been shown to mediate complex formation and, therefore, special attention is paid to this factor in this study. 相似文献23.
Dunn EK Shoue DA Huang X Kline RE MacKay AL Carpita NC Taylor IE Mandoli DF 《Plant & cell physiology》2007,48(1):122-133
Although the Dasycladalean alga Acetabularia acetabulum has long been known to contain mannan-rich walls, it is not known to what extent wall composition varies as a function of the elaborate cellular differentiation of this cell, nor has it been determined what other polysaccharides accompany the mannans. Cell walls were prepared from rhizoids, stalks, hairs, hair scars, apical septa, gametophores and gametangia, subjected to nuclear magnetic resonance and Fourier transform infrared spectroscopy, and analyzed for monosaccharide composition and linkage, although material limitations prevented some cell regions from being analyzed by some of the methods. In diplophase, walls contain a para-crystalline mannan, with other polysaccharides accounting for 10-20% of the wall mass; in haplophase, gametangia have a cellulosic wall, with mannans and other polymers representing about a quarter of the mass. In the walls of the diplophase, the mannan appears less crystalline than typical of cellulose. The walls of both diploid and haploid phases contain little if any xyloglucan or pectic polysaccharides, but appear to contain small amounts of a homorhamnan, galactomannans and glucogalactomannans, and branched xylans. These ancillary polysaccharides are approximately as abundant in the cellulose-rich gametangia as in the mannan-rich diplophase. In the diplophase, different regions of the cell differ modestly but reproducibly in the composition of the cell wall. These results suggest unique cell wall architecture for the mannan-rich cell walls of the Dasycladales. 相似文献
24.
The STE4 and STE18 genes of yeast encode potential beta and gamma subunits of the mating factor receptor-coupled G protein 总被引:85,自引:0,他引:85
M Whiteway L Hougan D Dignard D Y Thomas L Bell G C Saari F J Grant P O'Hara V L MacKay 《Cell》1989,56(3):467-477
The STE4 and STE18 genes are required for haploid yeast cell mating. Sequencing of the cloned genes revealed that the STE4 polypeptide shows extensive homology to the beta subunits of mammalian G proteins, while the STE18 polypeptide shows weak similarity to the gamma subunit of transducin. Null mutations in either gene can suppress the haploid-specific cell-cycle arrest caused by mutations in the SCG1 gene (previously shown to encode a protein with similarity to the alpha subunit of G proteins). We propose that the products of the STE4 and STE18 genes comprise the beta and gamma subunits of a G protein complex coupled to the mating pheromone receptors. The genetic data suggest pheromone-receptor binding leads to the dissociation of the alpha subunit from beta gamma (as shown for mammalian G proteins), and the free beta gamma element initiates the pheromone response. 相似文献
25.
Genomic selection (GS) is of interest in breeding because of its potential for
predicting the genetic value of individuals and increasing genetic gains per unit of
time. To date, very few studies have reported empirical results of GS potential in
the context of large population sizes and long breeding cycles such as for boreal
trees. In this study, we assessed the effectiveness of marker-aided selection in an
undomesticated white spruce (Picea glauca (Moench) Voss) population of large
effective size using a GS approach. A discovery population of 1694 trees
representative of 214 open-pollinated families from 43 natural populations was
phenotyped for 12 wood and growth traits and genotyped for 6385 single-nucleotide
polymorphisms (SNPs) mined in 2660 gene sequences. GS models were built to predict
estimated breeding values using all the available SNPs or SNP subsets of the largest
absolute effects, and they were validated using various cross-validation schemes. The
accuracy of genomic estimated breeding values (GEBVs) varied from 0.327 to 0.435 when
the training and the validation data sets shared half-sibs that were on average
90% of the accuracies achieved through traditionally estimated breeding
values. The trend was also the same for validation across sites. As expected, the
accuracy of GEBVs obtained after cross-validation with individuals of unknown
relatedness was lower with about half of the accuracy achieved when half-sibs were
present. We showed that with the marker densities used in the current study,
predictions with low to moderate accuracy could be obtained within a large
undomesticated population of related individuals, potentially resulting in larger
gains per unit of time with GS than with the traditional approach. 相似文献
26.
Background
Previous studies have demonstrated an association between preterm delivery and increased risk of special educational need (SEN). The aim of our study was to examine the risk of SEN across the full range of gestation.Methods and Findings
We conducted a population-based, retrospective study by linking school census data on the 407,503 eligible school-aged children resident in 19 Scottish Local Authority areas (total population 3.8 million) to their routine birth data. SEN was recorded in 17,784 (4.9%) children; 1,565 (8.4%) of those born preterm and 16,219 (4.7%) of those born at term. The risk of SEN increased across the whole range of gestation from 40 to 24 wk: 37–39 wk adjusted odds ratio (OR) 1.16, 95% confidence interval (CI) 1.12–1.20; 33–36 wk adjusted OR 1.53, 95% CI 1.43–1.63; 28–32 wk adjusted OR 2.66, 95% CI 2.38–2.97; 24–27 wk adjusted OR 6.92, 95% CI 5.58–8.58. There was no interaction between elective versus spontaneous delivery. Overall, gestation at delivery accounted for 10% of the adjusted population attributable fraction of SEN. Because of their high frequency, early term deliveries (37–39 wk) accounted for 5.5% of cases of SEN compared with preterm deliveries (<37 wk), which accounted for only 3.6% of cases.Conclusions
Gestation at delivery had a strong, dose-dependent relationship with SEN that was apparent across the whole range of gestation. Because early term delivery is more common than preterm delivery, the former accounts for a higher percentage of SEN cases. Our findings have important implications for clinical practice in relation to the timing of elective delivery. Please see later in the article for the Editors'' Summary 相似文献27.
D Dudley Williams Sarah E MacKay Ralf C M Verdonschot Pierre J P Tacchino 《Journal of vector ecology》2007,32(2):328-335
Ochlerotatus triseriatus, the eastern treehole mosquito, reaches its northernmost range limit in the extreme southeast of Canada. As a known vector of West Nile and La Crosse encephalitis viruses and a potential vector of eastern equine encephalitis, its population biology is of interest. In southern Ontario, high larval densities occur in urban woodlots within sugar maple and American beech treehole communities comprising rotifers, nematode worms, mites, other dipterans, and scirtid beetles. Treehole water was characterized by low dissolved oxygen levels and seasonally variable pH and temperature, with the latter being most influential on local populations. Densities were significantly higher (up to 503 larvae 100 ml(-1)) in tree holes close to the forest floor (<1 m) and in experimental tree holes seeded with autumn-shed maple leaves as opposed to leaves of black oak and beech. In this locality, weekly sampling showed Oc. triseriatus to be multivoltine, with mass egg hatching beginning under coldwater (<10 degrees C) conditions in March/April, and thereafter producing three successful generations with a possible, less successful fourth in late summer. Some 1st instar larvae were present in water as cold as 0.7 degree C. Compared with larval psychodids living in the same tree hole, population losses of Oc. triseriatus due to washout during major rainfall events were negligible despite high flowthrough of water derived from stemflow. 相似文献
28.
P. Catry M. C. Silva S. MacKay A. Campos J. Masello P. Quillfeldt I. J. Strange 《Polar Biology》2007,30(3):391-394
Small burrowing petrels nesting on islands rarely survive introductions of mammalian predators. On New Island, a population
of around two million pairs of thin-billed prions nests despite the presence of introduced ship rats, house mice and feral
cats. Understanding the mechanisms of such coexistence is important, as it is important to establish a baseline for future
monitoring. To do this, prion breeding success was determined for 7 years and in several habitats. Breeding success was high,
except for the small fraction of the population that nests in tussock Poa flabellata stands, where several lines of evidence suggest significant predation by rats. Such high breeding success possibly resulted
from predator swamping in this highly seasonal environment. This study suggests that introduced mammals do not currently depress
thin-billed prion breeding success on New Island. However, cats and rodents might have future harmful effects if external
factors depressed the prion population or allow a significant population growth of predators on New Island. 相似文献
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