全文获取类型
收费全文 | 106篇 |
免费 | 9篇 |
国内免费 | 2篇 |
专业分类
117篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 9篇 |
2014年 | 6篇 |
2013年 | 1篇 |
2012年 | 2篇 |
2011年 | 1篇 |
2010年 | 5篇 |
2009年 | 5篇 |
2008年 | 2篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2005年 | 4篇 |
2004年 | 6篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1969年 | 2篇 |
1962年 | 2篇 |
1945年 | 1篇 |
1939年 | 1篇 |
排序方式: 共有117条查询结果,搜索用时 15 毫秒
61.
L. Y. Mackey B. Winnepenninckx R. De Wachter T. Backeljau P. Emschermann J. R. Garey 《Journal of molecular evolution》1996,42(5):552-559
The Ento- and Ectoprocta are sometimes placed together in the Bryozoa, which have variously been regarded as proto- or deuterostomes.
However, Entoprocta have also been allied to the pseudocoelomates, while Ectoprocta are often united with the Brachiopoda
and Phoronida in the (super)phylum Lophophorata. Hence, the phylogenetic relationships of these taxa are still much debated.
We determined complete 18S rRNA sequences of two entoprocts, an ectoproct, an inarticulate brachiopod, a phoronid, two annelids,
and a platyhelminth. Phylogenetic analyses of these data show that (1) entoprocts and lophophorates have spiralian, protostomous
affinities, (2) Ento- and Ectoprocta are not sister taxa, (3) phoronids and brachiopods form a monophyletic clade, and (4)
neither Ectoprocta or Annelida appear to be monophyletic. Both deuterostomous and pseudocoelomate features may have arisen
at least two times in evolutionary history. These results advocate a Spiralia-Radialia-based classification rather than one
based on the Protostomia-Deuterostomia concept.
Correspondence to: J.R. Garey 相似文献
62.
Circulatory adjustment in pearl divers 总被引:2,自引:0,他引:2
63.
Luís Felipe Toledo Michel V. Garey Thais R. N. Costa Ricardo Louren?o-de-Moraes Marília T. Hartmann Célio F. B. Haddad 《Journal of Ethology》2012,30(2):331-336
Diversity in reproductive modes is well known in amphibians, mainly among anurans, which are characterized by a diversity
in breeding biology that exceeds that of any other tetrapod. Currently, 39 reproductive modes are recognized among anurans
and some species display more than one mode. The breeding biology of some Brazilian Atlantic forest anurans was investigated
for this study. We observed unreported reproductive modes for six species, variability in the reproductive modes of individuals
of the same species (whereby some individuals of a given population displayed unusual reproductive modes when the physical
conditions of the breeding site were suboptimal), and variations within the modes. These observations suggest possible evolutionary
steps for the reproductive modes. Anuran breeding biology seems to be more diverse than previously reported, and a character
matrix could be constructed to describe the total range of variation of the anuran reproductive modes. 相似文献
64.
65.
The hypothesis that molting protostomes such as nematodes and arthropods form a monophyletic group known as Ecdysozoa is directly opposed to Articulata, in which some segmented protostomes such as annelids and arthropods form a monophyletic taxon. Ultrastructural and cladistic studies have led to the widely accepted hypothesis that nematodes belong among the protostomes. While early molecular studies suggested that nematodes were basal triploblasts, more recent molecular evidence suggests that this was an artifact of ‘long branch attraction’ and 18S rRNA gene, total evidence and hox gene studies all support the placement of nematodes within Ecdysozoa. The branching pattern within Ecdysozoa has been difficult to elucidate, but it now appears that priapulids and kinorhynchs form the earliest branching clade, followed by nematodes + nematomorphs, and finally the panarthropods. This suggests that Cycloneuralia is paraphyletic and that arthropods are the most derived of the ecdysozoans. 相似文献
66.
Garey JR 《Integrative and comparative biology》2002,42(3):611-618
Most biologists are familiar only with a few of the approximately40 extant animal phyla. The purpose of this symposium was torenew interest in the lesser-known invertebrate taxa, encouragetheir use in research and teaching and to promote the relevanceof high-level systematic studies. This paper reviews the twomajor views of metazoan evolutionary relationships with particularattention to the lesser-known taxa and to some of the new and/orconflicting terminology used in current animal phylogeneticstudy. The current use of lesser-known taxa in research is brieflydescribed, and the discussion that followed the symposium issummarized. The paper concludes with a brief history of thesymposium and a tribute to Robert P. Higgins, who organizedthree "Symposia on the Lesser-Known Invertebrates" over thepast 25 yr. 相似文献
67.
Using a comparative genomics approach we demonstrate a negative correlation between the number of codon reassignments undergone
by 222 mitochondrial genomes and the mitochondrial genome size, the number of mitochondrial ORFs, and the sizes of the large
and small subunit mitochondrial rRNAs. In addition, we show that the TGA-to-tryptophan codon reassignment, which has occurred
11 times in mitochondrial genomes, is found in mitochondrial genomes smaller than those which have not undergone the reassignment.
We therefore propose that mitochondrial codon reassignments occur in a wide range of phyla, particularly in Metazoa, due to
a reduced “proteomic constraint” on the mitochondrial genetic code, compared to the nuclear genetic code. The reduced proteomic
constraint reflects the small size of the mitochondrial-encoded proteome and allows codon reassignments to occur with less
likelihood of lethality. In addition, we demonstrate a striking link between nonsense codon reassignments and the decoding
properties of naturally occurring nonsense suppressor tRNAs. This suggests that natural preexisting nonsense suppression facilitated
nonsense codon reassignments and constitutes a novel mechanism of genetic code change. These findings explain for the first
time the identity of the stop codons and amino acids reassigned in mitochondrial and nuclear genomes. Nonsense suppressor
tRNAs provided the raw material for nonsense codon reassignments, implying that the properties of the tRNA anticodon have
dictated the identity of nonsense codon reassignments.
Electronic Supplementary Material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
[Reviewing Editor: Dr. Laura Landweber] 相似文献
68.
Inferences for a semiparametric model with panel data 总被引:1,自引:0,他引:1
69.
Lu Tian Hua Jin Hajime Uno Ying Lu Bo Huang Keaven M. Anderson LJ Wei 《Biometrics》2020,76(4):1157-1166
The t-year mean survival or restricted mean survival time (RMST) has been used as an appealing summary of the survival distribution within a time window [0, t]. RMST is the patient's life expectancy until time t and can be estimated nonparametrically by the area under the Kaplan-Meier curve up to t. In a comparative study, the difference or ratio of two RMSTs has been utilized to quantify the between-group-difference as a clinically interpretable alternative summary to the hazard ratio. The choice of the time window [0, t] may be prespecified at the design stage of the study based on clinical considerations. On the other hand, after the survival data have been collected, the choice of time point t could be data-dependent. The standard inferential procedures for the corresponding RMST, which is also data-dependent, ignore this subtle yet important issue. In this paper, we clarify how to make inference about a random “parameter.” Moreover, we demonstrate that under a rather mild condition on the censoring distribution, one can make inference about the RMST up to t, where t is less than or even equal to the largest follow-up time (either observed or censored) in the study. This finding reduces the subjectivity of the choice of t empirically. The proposal is illustrated with the survival data from a primary biliary cirrhosis study, and its finite sample properties are investigated via an extensive simulation study. 相似文献
70.