全文获取类型
收费全文 | 437篇 |
免费 | 33篇 |
专业分类
470篇 |
出版年
2022年 | 6篇 |
2021年 | 15篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2017年 | 9篇 |
2016年 | 8篇 |
2015年 | 18篇 |
2014年 | 28篇 |
2013年 | 19篇 |
2012年 | 34篇 |
2011年 | 33篇 |
2010年 | 23篇 |
2009年 | 24篇 |
2008年 | 34篇 |
2007年 | 35篇 |
2006年 | 24篇 |
2005年 | 21篇 |
2004年 | 28篇 |
2003年 | 14篇 |
2002年 | 16篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1992年 | 1篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 5篇 |
1972年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有470条查询结果,搜索用时 0 毫秒
11.
Background
The ChickRH6 whole chicken genome radiation hybrid (RH) panel recently produced has already been used to build radiation hybrid maps for several chromosomes, generating comparative maps with the human and mouse genomes and suggesting improvements to the chicken draft sequence assembly. Here we present the construction of a RH map of chicken chromosome 2. Markers from the genetic map were used for alignment to the existing GGA2 (Gallus gallus chromosome 2) linkage group and EST were used to provide valuable comparative mapping information. Finally, all markers from the RH map were localised on the chicken draft sequence assembly to check for eventual discordances.Results
Eighty eight microsatellite markers, 10 genes and 219 EST were selected from the genetic map or on the basis of available comparative mapping information. Out of these 317 markers, 270 gave reliable amplifications on the radiation hybrid panel and 198 were effectively assigned to GGA2. The final RH map is 2794 cR6000 long and is composed of 86 framework markers distributed in 5 groups. Conservation of synteny was found between GGA2 and eight human chromosomes, with segments of conserved gene order of varying lengths.Conclusion
We obtained a radiation hybrid map of chicken chromosome 2. Comparison to the human genome indicated that most of the 8 groups of conserved synteny studied underwent internal rearrangements. The alignment of our RH map to the first draft of the chicken genome sequence assembly revealed a good agreement between both sets of data, indicative of a low error rate. 相似文献12.
Identification and Localization of a Rickettsia sp. in Bemisia tabaci (Homoptera: Aleyrodidae) 总被引:1,自引:0,他引:1 下载免费PDF全文
Yuval Gottlieb Murad Ghanim Elad Chiel Dan Gerling Vitaly Portnoy Shimon Steinberg Galil Tzuri A. Rami Horowitz Eduard Belausov Neta Mozes-Daube Svetlana Kontsedalov Moshe Gershon Shunit Gal Nurit Katzir Einat Zchori-Fein 《Applied microbiology》2006,72(5):3646-3652
Whiteflies (Homoptera: Aleyrodidae) are sap-sucking insects that harbor “Candidatus Portiera aleyrodidarum,” an obligatory symbiotic bacterium which is housed in a special organ called the bacteriome. These insects are also home for a diverse facultative microbial community which may include Hamiltonella, Arsenophonus, Fritchea, Wolbachia, and Cardinium spp. In this study, the bacteria associated with a B biotype of the sweet potato whitefly Bemisia tabaci were characterized using molecular fingerprinting techniques, and a Rickettsia sp. was detected for the first time in this insect family. Rickettsia sp. distribution, transmission and localization were studied using PCR and fluorescence in situ hybridizations (FISH). Rickettsia was found in all 20 Israeli B. tabaci populations screened but not in all individuals within each population. A FISH analysis of B. tabaci eggs, nymphs, and adults revealed a unique concentration of Rickettsia around the gut and follicle cells, as well as a random distribution in the hemolymph. We postulate that the Rickettsia enters the oocyte together with the bacteriocytes, leaves these symbiont-housing cells when the egg is laid, multiplies and spreads throughout the egg during embryogenesis and, subsequently, disperses throughout the body of the hatching nymph, excluding the bacteriomes. Although the role Rickettsia plays in the biology of the whitefly is currently unknown, the vertical transmission on the one hand and the partial within-population infection on the other suggest a phenotype that is advantageous under certain conditions but may be deleterious enough to prevent fixation under others. 相似文献
13.
14.
The geography of snake reproductive mode: a global analysis of the evolution of snake viviparity 下载免费PDF全文
15.
16.
Meiotic programmed DNA double-strand break (DSB) repair is essential for crossing-over and viable gamete formation and requires removal of Spo11-oligonucleotide complexes from 5′ ends (clipping) and their resection to generate invasive 3′-end single-stranded DNA (resection). Ctp1 (Com1, Sae2, CtIP homolog) acting with the Mre11-Rad50-Nbs1 (MRN) complex is required in both steps. We isolated multiple S. pombe ctp1 mutants deficient in clipping but proficient in resection during meiosis. Remarkably, all of the mutations clustered in or near the conserved CxxC or RHR motif in the C-terminal portion. The mutants tested, like ctp1Δ, were clipping-deficient by both genetic and physical assays. But, unlike ctp1Δ, these mutants were recombination-proficient for Rec12 (Spo11 homolog)-independent break-repair and resection-proficient by physical assay. We conclude that the intracellular Ctp1 C-terminal portion is essential for clipping, while the N-terminal portion is sufficient for DSB end-resection. This conclusion agrees with purified human CtIP resection and endonuclease activities being independent. Our mutants provide intracellular evidence for separable functions of Ctp1. Some mutations truncate Ctp1 in the same region as one of the CtIP mutations linked to the Seckel and Jawad severe developmental syndromes, suggesting that these syndromes are caused by a lack of clipping at DSB ends that require repair. 相似文献
17.
Tamar Erez † Jutta M. Schneider‡ & Yael Lubin 《Ethology : formerly Zeitschrift fur Tierpsychologie》2005,111(7):693-704
Reproductive interests of females and males can vary over a number of issues, including the number of matings and the occurrence and duration of mate guarding and cohabitation. The mating system of the spider Stegodyphus lineatus (Eresidae) is characterized by an exceptional sexual conflict where males induce females to remate by committing infanticide. Females experience high costs because of this male strategy, while males benefit. During the mating season, males tend to stay with females for several days. We examined whether this male strategy of cohabitation is also disadvantageous for females of S. lineatus. A field experiment revealed that male presence in a female's nest negatively affected her body condition, whereas cohabiting males gained weight because they fed on prey caught in webs of females. As a response, females did not renew their webs when males were present. Thus, females with a cohabiting male experienced the combined cost of prey loss and loss of time available for foraging. These costs are expected to increase with every additional cohabiting male. Mated females behaved more aggressively toward males than did virgin females. This behavior may be interpreted as an adaptive response to reduce mating costs. 相似文献
18.
Neta Degani Yoav Lubelsky Rotem Ben-Tov Perry Elena Ainbinder Igor Ulitsky 《PLoS genetics》2021,17(7)
Long noncoding RNAs (lncRNAs) have been shown to play important roles in gene regulatory networks acting in early development. There has been rapid turnover of lncRNA loci during vertebrate evolution, with few human lncRNAs conserved beyond mammals. The sequences of these rare deeply conserved lncRNAs are typically not similar to each other. Here, we characterize HOXA-AS3 and HOXB-AS3, lncRNAs produced from the central regions of the HOXA and HOXB clusters. Sequence-similar orthologs of both lncRNAs are found in multiple vertebrate species and there is evident sequence similarity between their promoters, suggesting that the production of these lncRNAs predates the duplication of the HOX clusters at the root of the vertebrate lineage. This conservation extends to similar expression patterns of the two lncRNAs, in particular in cells transiently arising during early development or in the adult colon. Functionally, the RNA products of HOXA-AS3 and HOXB-AS3 regulate the expression of their overlapping HOX5–7 genes both in HT-29 cells and during differentiation of human embryonic stem cells. Beyond production of paralogous protein-coding and microRNA genes, the regulatory program in the HOX clusters therefore also relies on paralogous lncRNAs acting in restricted spatial and temporal windows of embryonic development and cell differentiation. 相似文献
19.
Matthew H. Van Dam Analyn Anzano Cabras James B. Henderson Andrew J. Rominger Cynthia Prez Estrada Arina D. Omer Olga Dudchenko Erez Lieberman Aiden Athena W. Lam 《PLoS genetics》2021,17(8)
Patterns of genomic architecture across insects remain largely undocumented or decoupled from a broader phylogenetic context. For instance, it is unknown whether translocation rates differ between insect orders. We address broad scale patterns of genome architecture across Insecta by examining synteny in a phylogenetic framework from open-source insect genomes. To accomplish this, we add a chromosome level genome to a crucial lineage, Coleoptera. Our assembly of the Pachyrhynchus sulphureomaculatus genome is the first chromosome scale genome for the hyperdiverse Phytophaga lineage and currently the largest insect genome assembled to this scale. The genome is significantly larger than those of other weevils, and this increase in size is caused by repetitive elements. Our results also indicate that, among beetles, there are instances of long-lasting (>200 Ma) localization of genes to a particular chromosome with few translocation events. While some chromosomes have a paucity of translocations, intra-chromosomal synteny was almost absent, with gene order thoroughly shuffled along a chromosome. This large amount of reshuffling within chromosomes with few inter-chromosomal events contrasts with patterns seen in mammals in which the chromosomes tend to exchange larger blocks of material more readily. To place our findings in an evolutionary context, we compared syntenic patterns across Insecta in a phylogenetic framework. For the first time, we find that synteny decays at an exponential rate relative to phylogenetic distance. Additionally, there are significant differences in decay rates between insect orders, this pattern was not driven by Lepidoptera alone which has a substantially different rate. 相似文献
20.
Nataly Mancette Rijensky Netta R. Blondheim Shraga Eilon Barnea Nir Peled Eli Rosenbaum Aron Popovtzer Solomon M. Stemmer Alejandro Livoff Mark Shlapobersky Neta Moskovits Dafna Perry Eitan Rubin Itzhak Haviv Arie Admon 《Molecular & cellular proteomics : MCP》2020,19(8):1360-1374
Highlights
- •Sufficient tumor tissues are often unavailable large HLA peptidome discovery.
- •Using patient derived xenograft (PDX) tumors can overcome this limitation.
- •The large PDX HLA peptidomes expand significantly those of the original biopsies.
- •The HLA peptidomes of the PDX tumors included many tumor antigens.