全文获取类型
收费全文 | 1582篇 |
免费 | 123篇 |
出版年
2024年 | 3篇 |
2023年 | 13篇 |
2022年 | 35篇 |
2021年 | 71篇 |
2020年 | 33篇 |
2019年 | 44篇 |
2018年 | 61篇 |
2017年 | 48篇 |
2016年 | 69篇 |
2015年 | 98篇 |
2014年 | 93篇 |
2013年 | 102篇 |
2012年 | 157篇 |
2011年 | 140篇 |
2010年 | 75篇 |
2009年 | 74篇 |
2008年 | 81篇 |
2007年 | 86篇 |
2006年 | 73篇 |
2005年 | 69篇 |
2004年 | 68篇 |
2003年 | 35篇 |
2002年 | 40篇 |
2001年 | 18篇 |
2000年 | 11篇 |
1999年 | 12篇 |
1998年 | 7篇 |
1997年 | 7篇 |
1996年 | 8篇 |
1995年 | 4篇 |
1994年 | 10篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 5篇 |
1976年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有1705条查询结果,搜索用时 15 毫秒
141.
142.
143.
144.
145.
146.
A phylogeographical perspective on the ex situ conservation of Aylacostoma (Thiaridae,Gastropoda) from the High Paraná River (Argentina–Paraguay)
下载免费PDF全文
![点击此处可从《Zoological Journal of the Linnean Society》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Roberto E. Vogler Ariel A. Beltramino Ellen E. Strong Juana G. Peso Alejandra Rumi 《Zoological Journal of the Linnean Society》2015,174(3):487-499
Aylacostoma Spix, 1827, contains species that are the subject of focused conservation efforts under the auspices of the ‘Aylacostoma Project’, the only ex situ conservation programme for freshwater gastropods in South America. Two species from the High Paraná River (Argentina–Paraguay) are included in this programme (Aylacostoma chloroticum Hylton Scott, 1954 and Aylacostoma brunneum Vogler & Peso, 2014), as their habitats have disappeared as a consequence of the filling of the Yacyretá Reservoir in the 1990s. At present, A. chloroticum is restricted to only one known wild population in a small and fragile habitat, and wild populations of A. brunneum are presumed to have gone extinct. We used partial sequences of the cytochrome oxidase subunit I gene to provide the first phylogeographical perspective on these species from a limited dataset containing representatives of several wild populations that are successfully being bred in captivity. We found low genetic diversity and two haplotypes in A. chloroticum, and absence of variation with one haplotype in A. brunneum. The reservoir's entry zone was identified to be of great interest for conservation, and is where we suggest re‐introductions and translocations should be targeted, to preserve the future evolutionary potential of the extant diversity. © 2015 The Linnean Society of London 相似文献
147.
Cristina Lemini Ruth Jaimez Alejandra Figueroa Lucía Martinez-Mota María Estela Avila Martha Medina 《Experimental Animals》2015,64(1):81-89
Rodent ovariectomy is an experimental method to eliminate the main source of sexual
steroids. This work explored for the first time the ovariectomy temporal changes induced
in the hemostatic coagulation markers: prothrombin time (PT), activated partial
thromboplastin time (aPTT), thrombin time (TT), and fibrinogen concentration (FIB) along
with uterine weight on adult female CD1 mice and Wistar rats. Uterine weight (Uw) was
assessed before ovariectomy (control), and 1, 3, 5, 7, 9, 16, and 21 days after surgery.
PT, aPTT, TT and FIB were estimated the same days, using reported standard techniques.
Ovariectomy decreased Uw, since day 1; and from day 10 to 21 reached the lowest values for
both species. After day 1, mice hemostatic parameters changed (PT +10%,
P<0.05; aPTT +53%, P<0.05; TT −24%,
P<0.05; FIB +67%, P<0.05). Rats showed
significant changes only in TT and FIB (TT −13%, P<0.001; FIB +65%,
P<0.001). Neither mice PT, aPTT and TT, recovered control values
after 21 days. In the rats from day 5 to 16 aPTT diminished (18–23%,
P<0.05) recovering to control values on day 21, TT after 9 days and PT
on day 16. In both species, FIB returned to its control values after 9 days. Ovariectomy
differentially altered the PT hemostatic parameter of mice and rats indicating a
non-equivalence among both species behaviour for experimental studies of blood
coagulation. 相似文献
148.
Caroline Monat Cecilia Quiroga Felix Laroche-Johnston Benoit Cousineau 《RNA (New York, N.Y.)》2015,21(7):1286-1293
Group II introns are large ribozymes that require the assistance of intron-encoded or free-standing maturases to splice from their pre-mRNAs in vivo. They mainly splice through the classical branching pathway, being released as RNA lariats. However, group II introns can also splice through secondary pathways like hydrolysis and circularization leading to the release of linear and circular introns, respectively. Here, we assessed in vivo splicing of various constructs of the Ll.LtrB group II intron from the Gram-positive bacterium Lactococcus lactis. The study of excised intron junctions revealed, in addition to branched intron lariats, the presence of perfect end-to-end intron circles and alternatively circularized introns. Removal of the branch point A residue prevented Ll.LtrB excision through the branching pathway but did not hinder intron circle formation. Complete intron RNA circles were found associated with the intron-encoded protein LtrA forming nevertheless inactive RNPs. Traces of double-stranded head-to-tail intron DNA junctions were also detected in L. lactis RNA and nucleic acid extracts. Some intron circles and alternatively circularized introns harbored variable number of non-encoded nucleotides at their splice junction. The presence of mRNA fragments at the splice junction of some intron RNA circles provides insights into the group II intron circularization pathway in bacteria. 相似文献
149.
Sigmer Y. Quiroga E. Carolina Bonilla D. Marcela Bola?os Fernando Carbayo Marian K. Litvaitis Federico D. Brown 《Genetics and molecular biology》2015,38(3):233-248
The nervous systems of flatworms have diversified extensively as a consequence of the broad range of adaptations in the group. Here we examined the central nervous system (CNS) of 12 species of polyclad flatworms belonging to 11 different families by morphological and histological studies. These comparisons revealed that the overall organization and architecture of polyclad central nervous systems can be classified into three categories (I, II, and III) based on the presence of globuli cell masses -ganglion cells of granular appearance-, the cross-sectional shape of the main nerve cords, and the tissue type surrounding the nerve cords. In addition, four different cell types were identified in polyclad brains based on location and size. We also characterize the serotonergic and FMRFamidergic nervous systems in the cotylean Boninia divae by immunocytochemistry. Although both neurotransmitters were broadly expressed, expression of serotonin was particularly strong in the sucker, whereas FMRFamide was particularly strong in the pharynx. Finally, we test some of the major hypothesized trends during the evolution of the CNS in the phylum by a character state reconstruction based on current understanding of the nervous system across different species of Platyhelminthes and on up-to-date molecular phylogenies. 相似文献
150.
Fernández-Miranda G Trakala M Martín J Escobar B González A Ghyselinck NB Ortega S Cañamero M Pérez de Castro I Malumbres M 《Development (Cambridge, England)》2011,138(13):2661-2672
Mitosis is controlled by multiple kinases that drive cell cycle progression and prevent chromosome mis-segregation. Aurora kinase B interacts with survivin, borealin and incenp to form the chromosomal passenger complex (CPC), which is involved in the regulation of microtubule-kinetochore attachments and cytokinesis. Whereas genetic ablation of survivin, borealin or incenp results in early lethality at the morula stage, we show here that aurora B is dispensable for CPC function during early cell divisions and aurora B-null embryos are normally implanted. This is due to a crucial function of aurora C during these early embryonic cycles. Expression of aurora C decreases during late blastocyst stages resulting in post-implantation defects in aurora B-null embryos. These defects correlate with abundant prometaphase figures and apoptotic cell death of the aurora B-deficient inner cell mass. Conditional deletion of aurora B in somatic cells that do not express aurora C results in chromosomal misalignment and lack of chromosome segregation. Re-expression of wild-type, but not kinase-dead, aurora C rescues this defect, suggesting functional overlap between these two kinases. Finally, aurora B-null cells partially arrest in the presence of nocodazole, suggesting that this kinase is not essential for the spindle assembly checkpoint. 相似文献