全文获取类型
收费全文 | 559篇 |
免费 | 71篇 |
出版年
2021年 | 4篇 |
2020年 | 9篇 |
2019年 | 9篇 |
2018年 | 5篇 |
2017年 | 7篇 |
2016年 | 16篇 |
2015年 | 21篇 |
2014年 | 31篇 |
2013年 | 30篇 |
2012年 | 22篇 |
2011年 | 33篇 |
2010年 | 25篇 |
2009年 | 23篇 |
2008年 | 23篇 |
2007年 | 25篇 |
2006年 | 22篇 |
2005年 | 19篇 |
2004年 | 14篇 |
2003年 | 22篇 |
2002年 | 24篇 |
2001年 | 15篇 |
2000年 | 18篇 |
1999年 | 17篇 |
1998年 | 14篇 |
1997年 | 14篇 |
1996年 | 8篇 |
1995年 | 4篇 |
1994年 | 8篇 |
1992年 | 15篇 |
1991年 | 15篇 |
1990年 | 6篇 |
1989年 | 12篇 |
1988年 | 6篇 |
1987年 | 11篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1982年 | 7篇 |
1981年 | 7篇 |
1979年 | 5篇 |
1975年 | 3篇 |
1974年 | 7篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 6篇 |
1969年 | 3篇 |
1968年 | 2篇 |
1966年 | 3篇 |
1964年 | 2篇 |
1959年 | 2篇 |
排序方式: 共有630条查询结果,搜索用时 546 毫秒
571.
Debra L Fulton Yvonne Y Li Matthew R Laird Benjamin GS Horsman Fiona M Roche Fiona SL Brinkman 《BMC bioinformatics》2006,7(1):270-16
Background
Orthologs (genes that have diverged after a speciation event) tend to have similar function, and so their prediction has become an important component of comparative genomics and genome annotation. The gold standard phylogenetic analysis approach of comparing available organismal phylogeny to gene phylogeny is not easily automated for genome-wide analysis; therefore, ortholog prediction for large genome-scale datasets is typically performed using a reciprocal-best-BLAST-hits (RBH) approach. One problem with RBH is that it will incorrectly predict a paralog as an ortholog when incomplete genome sequences or gene loss is involved. In addition, there is an increasing interest in identifying orthologs most likely to have retained similar function. 相似文献572.
Rachid MA Camargos ER Barcellos L Marques CA Chiari E Huang H Tanowitz HB Teixeira MM Machado CR 《Microbes and infection / Institut Pasteur》2006,8(8):2113-2119
Endothelin has been implicated in the pathogenesis of experimental and human Chagas' disease (American trypanosomiasis). In the present study, we tested the effect of bosentan, an antagonist of both ET(A) and ET(B) endothelin receptors, on parasitemia, histopathology (heart and diaphragm), heart levels of tumor necrosis factor (TNF)-alpha, interleukin (IL)-10, interferon (IFN)-gamma, CCL2, CCL3 and CCL5, and the serum levels of nitrate/nitrite (NOx). Bosentan treatment was accompanied by a significant increase in parasitemia and tissue parasitism or inflammation. In vehicle-treated rats, Trypanosoma cruzi infection increased the cardiac levels of TNF-alpha, IFN-gamma and IL-10, at day 9 post inoculation, and the TNF-alpha remained elevated until day 13. The infection also caused a significant increase in the cardiac levels of the chemokines CCL2 (9, 13 and 18 days) and CCL3 (13 and 18 days). Bosentan-treatment had no significant effect on the infection-associated increase in IFN-gamma and chemokine concentrations. There was a lower increase in IL-10 at day 9 and this was mirrored by a greater increase of TNF-alpha at day 13, in comparison with vehicle-treated rats. These latter findings correlated well with the enhanced inflammatory process in hearts of bosentan-treated infected rats. Bosentan treatment reduced the infection-associated increase in NOx serum concentration. Altogether, our data suggest that ET action on ET(A) and ET(B) receptors may play a role in the initial control of T. cruzi infection in rats probably by interfering in NO production. 相似文献
573.
574.
575.
Sarah J. Adamowicz Adam Petrusek John K. Colbourne Paul D.N. Hebert Jonathan D.S. Witt 《Molecular phylogenetics and evolution》2009,50(3):423-436
Molecular studies have enlightened our understanding of freshwater zooplankton biogeography, yet questions remain regarding the scale and commonality of geographic speciation. Here, we present a mtDNA-based phylogenetic hypothesis for 92 Daphnia species from all seven continents, with a focus on North and South America, Europe, and Australia, and use it to explore the frequency, scale, and geographical orientation of allopatric divergence events. Allopatric speciation can conservatively account for at least 42% of cladogenetic events among the species included in our study; most of these involve intercontinental splits. Closely related species pairs are concentrated in the circumarctic region and between northern and southern continents, aligned with bird migration routes, suggesting recent dispersal. By contrast, deeper phylogenetic patterns are consistent with vicariance scenarios linked to continental fragmentation. The possible reasons for the puzzling persistence of these ancient patterns in light of the eroding force of dispersal are considered. Our results demonstrate the high frequency and complex pattern of allopatric speciation in this ancient, passively dispersed genus. 相似文献
576.
Coilin is a nuclear protein that plays a role in Cajal body formation. The function of nucleoplasmic coilin is unknown. Here we report that coilin interacts with Ku70 and Ku80, which are major players in the DNA repair process. Ku proteins compete with SMN and SmB′ proteins for coilin interaction sites. The binding domain on coilin for Ku proteins cannot be localized to one discrete region, and only full-length coilin is capable of inhibiting in vitro non-homologous DNA end joining (NHEJ). Since Ku proteins do not accumulate in CBs, these findings suggest that nucleoplasmic coilin participates in the regulation of DNA repair.
Structured summary
MINT-8052983:coilin (uniprotkb:P38432) physically interacts (MI:0915) with SmB′ (uniprotkb:P14678) by pull down (MI:0096)MINT-8052941:coilin (uniprotkb:P38432) physically interacts (MI:0915) with Ku70 (uniprotkb:P12956) by competition binding (MI:0405)MINT-8052765:coilin (uniprotkb:P38432) physically interacts (MI:0915) with Ku80 (uniprotkb:P13010) by pull down (MI:0096)MINT-8052971:coilin (uniprotkb:P38432) physically interacts (MI:0915) with SMN (uniprotkb:Q16637) by pull down (MI:0096)MINT-8052957:coilin (uniprotkb:P38432) physically interacts (MI:0915) with Ku80 (uniprotkb:P13010) by competition binding (MI:0405)MINT-8052894, MINT-8052908:coilin (uniprotkb:P38432) binds (MI:0407) to Ku80 (uniprotkb:P13010) by pull down (MI:0096)MINT-8052804:coilin (uniprotkb:P38432) physically interacts (MI:0915) with Ku80 (uniprotkb:P13010) by anti bait coimmunoprecipitation (MI:0006)MINT-8052925:coilin (uniprotkb:P38432) binds (MI:0407) to Ku70 (uniprotkb:P12956) by pull down (MI:0096)MINT-8052786:Ku80 (uniprotkb:P13010) physically interacts (MI:0914) with coilin (uniprotkb:P38432) and Ku70 (uniprotkb:P12956) by anti bait coimmunoprecipitation (MI:0006)MINT-8052776:coilin (uniprotkb:P38432) physically interacts (MI:0915) with Ku70 (uniprotkb:P12956) by pull down (MI:0096) 相似文献577.
Among the Kerguelen Islands' demersal fish, larvae of Lepidonotothen squamifrons are dominant during the summer over the island shelf and surrounding seamounts. Distribution of larval stages from different
scientific surveys confirmed the position of the two known spawning grounds (south of the Kerguelen shelf and at the Kerguelen-Heard
bank) and may indicate other spawnings on the Skiff bank and in bays and fjords. Different larval cohorts were observed for
the shelf and the coastal zone whereas a unique one was observed for Skiff and Kerguelen-Heard seamounts. Larvae from the
spawning ground south of the Kerguelen shelf appear in early summer and show a northwards dispersal to the northeastern nearshore
zone, the Baleiniers Gulf, following the scheme of fish migration shown by Harden-Jones. Later on, larvae from the northern
inshore spawning zone occur in the same area, which presumably then avoid intraspecific competition with the previous larvae.
Larval distribution and migration strategy seemed to be in accordance with the island mass or seamount effect under a regular
current.
Accepted: 2 December 1999 相似文献
578.
Biological identifications through DNA barcodes 总被引:82,自引:0,他引:82
Hebert PD Cywinska A Ball SL deWaard JR 《Proceedings. Biological sciences / The Royal Society》2003,270(1512):313-321
Although much biological research depends upon species diagnoses, taxonomic expertise is collapsing. We are convinced that the sole prospect for a sustainable identification capability lies in the construction of systems that employ DNA sequences as taxon 'barcodes'. We establish that the mitochondrial gene cytochrome c oxidase I (COI) can serve as the core of a global bioidentification system for animals. First, we demonstrate that COI profiles, derived from the low-density sampling of higher taxonomic categories, ordinarily assign newly analysed taxa to the appropriate phylum or order. Second, we demonstrate that species-level assignments can be obtained by creating comprehensive COI profiles. A model COI profile, based upon the analysis of a single individual from each of 200 closely allied species of lepidopterans, was 100% successful in correctly identifying subsequent specimens. When fully developed, a COI identification system will provide a reliable, cost-effective and accessible solution to the current problem of species identification. Its assembly will also generate important new insights into the diversification of life and the rules of molecular evolution. 相似文献
579.
Hans Hebert ers Olofsson Monica Thelestam Elisabeth Skriver 《FEMS microbiology letters》1992,105(1-3):5-12
Abstract The 12S oligomeric form of Staphylococcus aureus α-toxin has been studied with electron microscopy after incubation of the toxin with membrane preparations or liposomes. The target material originated from human platelet. Different electron microscopic preparation techniques were used including negative staining, freeze-fracture and vitrification in liquid ethane. Analysis of micrographs with image processing methods revealed two groups of ring-like structures corresponding to α-toxin oligomers. One form measured 75 Å in diameter and had a high stain density in the central protein deficient part while the other was larger with a diameter of 100 Å and less stain accumulation in the center. The conditions under which the latter were formed suggest that this corresponds to an inactive loosely-bound form of the toxin. The high stain density in the smaller particle is consistent with the presence of a penetrating pore in this structure. 相似文献
580.
Teresa L. Dzieweczynski Kalyn R. Sullivan Lindsay M. Forrette Olivia L. Hebert 《Ethology : formerly Zeitschrift fur Tierpsychologie》2012,118(4):351-359
Consistent individual differences in behavior suggest that individuals respond in a predictable and repeatable manner in a specific situation while differing from other individuals. Male Siamese fighting fish exhibit consistent individual differences in decision‐making strategies when they encounter a receptive female and a rival male simultaneously. However, whether these differences are altered by recent experience is unknown. We examined the influence of repeated aggressive encounters on behavioral consistency and decision‐making. Males were presented with paired female–male dummies prior to any aggressive experiences to obtain a baseline measure. Next, males either won or lost three consecutive contests against rivals and then received the paired female–male dummies after each of these encounters. Overall levels of highly aggressive behaviors were affected by contest outcome, while levels of female‐directed were not. Not surprisingly, winning a fight led to an increase in male‐directed bites, an overtly aggressive behavior that only occurs after fights have escalated. Fighting a male before encountering the dummies caused males to perform more tail beats to the dummy male, perhaps as a result of increased motivation. Males exhibited similar levels of repeatability and used the same strategies when faced with conflicting stimuli regardless of fighting experience. Thus, while winning or losing a fight impacts overall aggression, it does not influence behavioral consistency. This study demonstrates that consistent individual differences and decision‐making strategies may be resistant to recent aggressive experiences, even over a period of days. 相似文献