全文获取类型
收费全文 | 212篇 |
免费 | 17篇 |
专业分类
229篇 |
出版年
2022年 | 3篇 |
2021年 | 3篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 5篇 |
2016年 | 3篇 |
2015年 | 11篇 |
2014年 | 16篇 |
2013年 | 21篇 |
2012年 | 18篇 |
2011年 | 8篇 |
2010年 | 9篇 |
2009年 | 13篇 |
2008年 | 11篇 |
2007年 | 9篇 |
2006年 | 12篇 |
2005年 | 9篇 |
2004年 | 5篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 10篇 |
2000年 | 10篇 |
1999年 | 4篇 |
1998年 | 11篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1976年 | 2篇 |
1971年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有229条查询结果,搜索用时 31 毫秒
81.
Macquaridrilus mcmurtrieae n. sp. is described from Campbell Island. This resembles the only other species in the genus, Macquaridrilus bennettae Jamieson, 1968, in most aspects, but shows significant differences in the anatomy of its genitalia. In particular, the spermathecal pores are dorsal rather than lateral, the spermathecae lack diverticulae, the ejaculatory duct is more stout and muscular, the vas deferens is shorter relative to other organs and the anterior prostate is compact rather than elongate. The presence of a cuticular sperm canal appears to be an apomorphy for the genus. The new species was collected from streams and tarns across the island.http://zoobank.org/urn:lsid:zoobank.org:pub:652AF61D-CFB2-4D07-94C8-59E6FB549D5Fhttp://zoobank.org/urn:lsid:zoobank.org:act:984F2456-768D-48A1-87AD-4453768BAB8A 相似文献
82.
Background
Metabolically versatile soil bacteria Burkholderia cepacia complex (Bcc) have emerged as opportunistic pathogens, especially of cystic fibrosis (CF). Previously, we initiated the characterization of the phenylacetic acid (PA) degradation pathway in B. cenocepacia, a member of the Bcc, and demonstrated the necessity of a functional PA catabolic pathway for full virulence in Caenorhabditis elegans. In this study, we aimed to characterize regulatory elements and nutritional requirements that control the PA catabolic genes in B. cenocepacia K56-2. 相似文献83.
In a simulation study different designs for a pure line pig population were compared for efficiency of mapping QTL using the variance component method. Phenotypes affected by a Mendelian QTL, a paternally expressed QTL, a maternally expressed QTL or by a QTL without an effect were simulated. In all alternative designs 960 progeny were phenotyped. Given the limited number of animals there is an optimum between the number of families and the family size. Estimation of Mendelian and parentally expressed QTL is more efficient in a design with large family sizes. Too small a number of sires should be avoided to minimize chances of sires to be non-segregating. When a large number of families is used, the number of haplotypes increases which reduces the accuracy of estimating the QTL effect and thereby reduces the power to show a significant QTL and to correctly position the QTL. Dense maps allow for smaller family size due to exploitation of LD-information. Given the different possible modes of inheritance of the QTL using 8 to16 boars, two litters per dam was optimal with respect to determining significance and correct location of the QTL for a data set consisting of 960 progeny. The variance component method combining linkage disequilibrium and linkage analysis seems to be an appropriate choice to analyze data sets which vary in marker density and which contain complex family structures. 相似文献
84.
Hendrik-Jan Megens Richard PMA Crooijmans Magali San Cristobal Xiao Hui Ning Li Martien AM Groenen 《遗传、选种与进化》2008,40(1):103-128
Microsatellite diversity in European and Chinese pigs was assessed using a pooled sampling method on 52 European and 46 Chinese pig populations. A Neighbor Joining analysis on genetic distances revealed that European breeds were grouped together and showed little evidence for geographic structure, although a southern European and English group could tentatively be assigned. Populations from international breeds formed breed specific clusters. The Chinese breeds formed a second major group, with the Sino-European synthetic Tia Meslan in-between the two large clusters. Within Chinese breeds, in contrast to the European pigs, a large degree of geographic structure was noted, in line with previous classification schemes for Chinese pigs that were based on morphology and geography. The Northern Chinese breeds were most similar to the European breeds. Although some overlap exists, Chinese breeds showed a higher average degree of heterozygosity and genetic distance compared to European ones. Between breed diversity was even more pronounced and was the highest in the Central Chinese pigs, reflecting the geographically central position in China. Comparing correlations between genetic distance and heterozygosity revealed that China and Europe represent different domestication or breed formation processes. A likely cause is a more diverse wild boar population in Asia, but various other possible contributing factors are discussed. 相似文献
85.
Background
It is widely accepted that genetic regulatory systems are 'modular', in that the whole system is made up of smaller 'subsystems' corresponding to specific biological functions. Most attempts to identify modules in genetic regulatory systems have relied on the topology of the underlying network. However, it is the temporal activity (dynamics) of genes and proteins that corresponds to biological functions, and hence it is dynamics that we focus on here for identifying subsystems. 相似文献86.
AMÉLIE VANTAUX SHARON SCHILLEWAERT THOMAS PARMENTIER WIM VAN DEN ENDE JOHAN BILLEN TOM WENSELEERS 《Ecological Entomology》2015,40(5):511-517
1. The aphid Aphis fabae (Scopoli) is facultatively tended by Lasius niger (Linnaeus) ants. Previously, we found that A. fabae colonies can be made up of several clones, and that clones display significant differences in the composition of their honeydew sugars, especially in the amount of the ant attractant sugar melezitose that they produce. 2. These clonal differences could greatly impact the strength of the mutualistic interaction with ants as well as the aphids' fitness. 3. Hence, the aim of this study was to compare the fitness of different A. fabae clones that differed in their melezitose secretion, and whether or not they were tended by ants. 4. Individual fitness indices, colony growth, and alate production of single‐clone aphid colonies were analysed. 5. The results demonstrate that the fitness consequences of ant attendance critically depend on an interaction between levels of melezitose production. In particular, we show that high‐melezitose secreting clones produce fewer alates and hence might have a lower dispersal ability in the presence of ants. 6. Furthermore, these data confirm previous evidence that ant attendance is costly and results in the production of fewer apterae. 相似文献
87.
K van Oers A W Santure I De Cauwer N EM van Bers R PMA Crooijmans B C Sheldon M E Visser J Slate M AM Groenen 《Heredity》2014,112(3):307-316
Linking variation in quantitative traits to variation in the genome is an important, butchallenging task in the study of life-history evolution. Linkage maps provide a valuabletool for the unravelling of such trait−gene associations. Moreover, they giveinsight into recombination landscapes and between-species karyotype evolution. Here weused genotype data, generated from a 10k single-nucleotide polymorphism (SNP) chip, ofover 2000 individuals to produce high-density linkage maps of the great tit (Parusmajor), a passerine bird that serves as a model species for ecological andevolutionary questions. We created independent maps from two distinct populations: acaptive F2-cross from The Netherlands (NL) and a wild population from the United Kingdom(UK). The two maps contained 6554 SNPs in 32 linkage groups, spanning 2010 cM and1917 cM for the NL and UK populations, respectively, and were similar in size andmarker order. Subtle levels of heterochiasmy within and between chromosomes wereremarkably consistent between the populations, suggesting that the local departures fromsex-equal recombination rates have evolved. This key and surprising result would have beenimpossible to detect if only one population was mapped. A comparison with zebra finchTaeniopygia guttata, chicken Gallus gallus and the green anole lizardAnolis carolinensis genomes provided further insight into the evolution ofavian karyotypes. 相似文献
88.
A plasmid library of Acinetobacter calcoaceticus HindIII fragments was
constructed, and clones that complemented an Escherichia coli pabA mutant
were selected. Plasmids containing a 3.9-kb fragment of A. calcoaceticus
DNA that also complemented E. coli trpD and trpC-(trpF+) mutants were
obtained. We infer that complementation of E. coli pabA mutants was the
result of the expression of the amphibolic anthranilate-
synthase/p-aminobenzoate-synthase glutamine-amidotransferase gene and that
the plasmid insert carried the entire trpGDC gene cluster. In E. coli
minicells, the plasmid insert directed the synthesis of polypeptides of
44,000, 33,000, and 20,000 daltons, molecular masses that are consistent
with the reported molecular masses of phosphoribosylanthranilate
transferase, indoleglycerol-phosphate synthase, and anthranilate-synthase
component II, respectively. A 3,105- bp nucleotide sequence was determined.
Comparison of the A. calcoaceticus trpGDC sequences with other known trp
gene sequences has allowed insight into (1) the evolution of the amphibolic
trpG gene, (2) varied strategies for coordinate expression of trp genes,
and (3) mechanisms of gene fusions in the trp operon.
相似文献
89.
Bellis M; Jubier-Maurin V; Dod B; Vanlerberghe F; Laurent AM; Senglat C; Bonhomme F; Roizes G 《Molecular biology and evolution》1987,4(4):351-363
The presence of the L1 sequences, L1Md4 next to the pseudogene beta h3 and
I12 found in the twelfth intron of the albumin gene, in certain strains of
laboratory mice but not of others has led to the suggestion that these
sequences were recent insertions into the Mus mus domesticus genome. To be
sure that they are really recent insertions and not relics of an ancestral
chromosome, we investigated the presence or absence of these sequences in
populations of wild mice belonging to the semispecies M. m. domesticus and
M. m. musculus as well as in other species of the genus Mus and in related
murids. The sequence I12 in the albumin gene was found in 34% of the
chromosomes of the wild mice belonging to M. m. domesticus and to a lesser
extent (6%) in M. m. musculus. Of 114 M. m. domesticus chromosomes, L1Md4
was found in only nine, seven of which came from the same locality. Its
presence was associated with the haplotype Hbbp, which is relatively rare
in European populations of M. musculus. Since there was no evidence for the
presence of these two L1 sequences in more distantly related species, we
conclude that they are recent insertions in the M. musculus genome.
相似文献
90.
Filip AM Volckaert Bart Hellemans Costas Batargias Bruno Louro Cécile Massault Jeroen KJ Van Houdt Chris Haley Dirk-Jan de Koning Adelino VM Canario 《遗传、选种与进化》2012,44(1):15