全文获取类型
收费全文 | 1262篇 |
免费 | 93篇 |
出版年
2022年 | 6篇 |
2021年 | 11篇 |
2020年 | 9篇 |
2019年 | 13篇 |
2018年 | 28篇 |
2017年 | 14篇 |
2016年 | 26篇 |
2015年 | 38篇 |
2014年 | 39篇 |
2013年 | 68篇 |
2012年 | 74篇 |
2011年 | 80篇 |
2010年 | 58篇 |
2009年 | 52篇 |
2008年 | 62篇 |
2007年 | 58篇 |
2006年 | 50篇 |
2005年 | 53篇 |
2004年 | 44篇 |
2003年 | 41篇 |
2002年 | 50篇 |
2001年 | 30篇 |
2000年 | 21篇 |
1999年 | 19篇 |
1998年 | 22篇 |
1997年 | 18篇 |
1996年 | 19篇 |
1995年 | 10篇 |
1994年 | 16篇 |
1993年 | 12篇 |
1992年 | 23篇 |
1991年 | 10篇 |
1990年 | 15篇 |
1989年 | 11篇 |
1988年 | 12篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 9篇 |
1984年 | 12篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1981年 | 18篇 |
1980年 | 10篇 |
1976年 | 9篇 |
1975年 | 7篇 |
1969年 | 6篇 |
1964年 | 8篇 |
1949年 | 6篇 |
1948年 | 7篇 |
1927年 | 5篇 |
排序方式: 共有1355条查询结果,搜索用时 15 毫秒
71.
Jorge Orós Natalia Montesdeoca María Camacho Alberto Arencibia Pascual Calabuig 《PloS one》2016,11(2)
Aims
The aims of this study were to analyze the causes of stranding of 1,860 loggerhead turtles (Caretta caretta) admitted at the Tafira Wildlife Rehabilitation Center in Gran Canaria Island, Spain, from 1998 to 2014, and to analyze the outcomes of the rehabilitation process to allow meaningful auditing of its quality.Methods
Primary causes of morbidity were classified into seven categories: entanglement in fishing gear and/or plastics, ingestion of hooks and monofilament lines, trauma, infectious disease, crude oil, other causes, and unknown/undetermined. Final dispositions were calculated as euthanasia (Er), unassisted mortality (Mr), and release (Rr) rates. Time to death (Td) for euthanized and dead turtles, and length of stay for released (Tr) turtles were evaluated.Results
The most frequent causes of morbidity were entanglement in fishing gear and/or plastics (50.81%), unknown/undetermined (20.37%), and ingestion of hooks (11.88%). The final disposition of the 1,634 loggerhead turtles admitted alive were: Er = 3.37%, Mr = 10.34%, and Rr = 86.29%. Er was significantly higher in the trauma category (18.67%) compared to the other causes of admission. The highest Mr was observed for turtles admitted due to trauma (30.67%). The highest Rr was observed in the crude oil (93.87%) and entanglement (92.38%) categories. The median Tr ranged from 12 days (unknown) to 70 days (trauma).Conclusions
This survey is the first large-scale epidemiological study on causes of stranding and mortality of Eastern Atlantic loggerheads and demonstrates that at least 71.72% of turtles stranded due to anthropogenic causes. The high Rr (86.29%) emphasizes the importance of marine rehabilitation centers for conservation purposes. The stratified analysis by causes of admission of the three final disposition rates, and the parameters Td and Tr should be included in the outcome research of the rehabilitation process of sea turtles in order to allow comparative studies between marine rehabilitation centers around the world. 相似文献72.
Ákos Szekrényes SungAe Suhr Park Marcia Santos Clarence Lew Aled Jones Ted Haxo 《MABS-AUSTIN》2016,8(1):56-64
An international team that included 20 independent laboratories from biopharmaceutical companies, universities, analytical contract laboratories and national authorities in the United States, Europe and Asia was formed to evaluate the reproducibility of sample preparation and analysis of N-glycans using capillary electrophoresis of 8-aminopyrene-1,3,6-trisulfonic acid (APTS)-labeled glycans with laser induced fluorescence (CE-LIF) detection (16 sites) and ultra high-performance liquid chromatography (UHPLC, 12 sites; results to be reported in a subsequent publication). All participants used the same lot of chemicals, samples, reagents, and columns/capillaries to run their assays. Migration time, peak area and peak area percent values were determined for all peaks with >0.1% peak area. Our results demonstrated low variability and high reproducibility, both, within any given site as well across all sites, which indicates that a standard N-glycan analysis platform appropriate for general use (clone selection, process development, lot release, etc.) within the industry can be established. 相似文献
73.
V. Pascual L. M. Medrano N. López-Palacios A. Bodas B. Dema M. Fernández-Arquero B. González-Pérez I. Salazar C. Nú?ez 《PloS one》2016,11(2)
Celiac disease (CD) is developed after gluten ingestion in genetically susceptible individuals. It can appear at any time in life, but some differences are commonly observed between individuals with onset early in life or in adulthood. We aimed to investigate the molecular basis underlying those differences. We collected 19 duodenal biopsies of children and adults with CD and compared the expression of 38 selected genes between each other and with the observed in 13 non-CD controls matched by age. A Bayesian methodology was used to analyze the differences of gene expression between groups. We found seven genes with a similarly altered expression in children and adults with CD when compared to controls (C2orf74, CCR6, FASLG, JAK2, IL23A, TAGAP and UBE2L3). Differences were observed in 13 genes: six genes being altered only in adults (IL1RL1, CD28, STAT3, TMEM187, VAMP3 and ZFP36L1) and two only in children (TNFSF18 and ICOSLG); and four genes showing a significantly higher alteration in adults (CCR4, IL6, IL18RAP and PLEK) and one in children (C1orf106). This is the first extensive study comparing gene expression in children and adults with CD. Differences in the expression level of several genes were found between groups, being notorious the higher alteration observed in adults. Further research is needed to evaluate the possible genetic influence underlying these changes and the specific functional consequences of the reported differences. 相似文献
74.
Description of a new epibiotic relationship (Suctorian–Copepoda) in NE Atlantic waters: from morphological to phylogenetic analyses
下载免费PDF全文
![点击此处可从《Acta zoologica》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Maria Gregori Gregorio Fernández‐Leborans Álvaro Roura Ángel F. González Santiago Pascual 《Acta zoologica》2016,97(2):165-176
Paraeuchaeta hebes is one of the most important carnivorous copepods in the coastal upwelling system off Galician waters (Ría de Vigo, NE Atlantic). A suctorian epibiont of the genus Pelagacineta was found attached to the surface of these copepods. The abundance and distribution on the copepod surface were analysed, taking into account the sex of the crustacean, revealing some preference for females and also a different attachment point in both sexes. The morphological study allowed us to identify a new species of this Suctoria epibiont as Pelagacineta hebensis. Moreover, the 18S rRNA gene was partially sequenced to inspect the phylogenetic position of Pelagacineta hebensis within the subclass Phyllopharyngea. The maximum‐likelihood (ML) tree obtained was consistent with the morphological and with previous molecular studies and showed that P. hebensis belongs to the order Endogenina, as a sister clade of the few taxa sequenced within this order. Including new genetic data to the Endogenina will allow building new hypothesis about the evolution of the most derived clade of suctorians. 相似文献
75.
76.
77.
78.
Hedges JF Buckner DL Rask KM Kerns HM Jackiw LO Trunkle TC Pascual DW Jutila MA 《Cellular immunology》2007,246(1):8-16
To better understand the roles of gammadelta T cells in mucosal infection, we utilized Salmonella enterica serovar Typhimurium (Salmonella serovar Typhimurium) infection in cattle as it closely approximates Salmonella serovar Typhimurium-induced enterocolitis in humans. Protein and gene expression in alphabeta and gammadelta T cells derived from lymphatic ducts draining the gut mucosa in Salmonella serovar Typhimurium-infected calves were analyzed. In calves with enterocolitis, general gene expression trends in gammadelta T cells suggested subtle activation and innate response, whereas alphabeta T cells were relatively quiescent following Salmonella serovar Typhimurium infection. An increase in IL-2R alpha expression on gammadelta T cells from infected calves and results from in vitro assays suggested that gammadelta T cells were primed by Salmonella serovar Typhimurium LPS to better respond to IL-2 and IL-15. Together with gene expression trends in vivo, these data support early priming activation of target tissue gammadelta T cells during Salmonella serovar Typhimurium infection. 相似文献
79.
The 13C NMR spectra of the bejarols isolated from Santolina oblongifolia suggest they are nerolidol derivatives with a 2,6-dialkyldihydropyranose structure. 相似文献
80.
Neuronal synchrony mediated by astrocytic glutamate through activation of extrasynaptic NMDA receptors 总被引:31,自引:0,他引:31
Fast excitatory neurotransmission is mediated by activation of synaptic ionotropic glutamate receptors. In hippocampal slices, we report that stimulation of Schaffer collaterals evokes in CA1 neurons delayed inward currents with slow kinetics, in addition to fast excitatory postsynaptic currents. Similar slow events also occur spontaneously, can still be observed when neuronal activity and synaptic glutamate release are blocked, and are found to be mediated by glutamate released from astrocytes acting preferentially on extrasynaptic NMDA receptors. The slow currents can be triggered by stimuli that evoke Ca2+ oscillations in astrocytes, including photolysis of caged Ca2+ in single astrocytes. As revealed by paired recording and Ca2+ imaging, a striking feature of this NMDA receptor response is that it occurs synchronously in multiple CA1 neurons. Our results reveal a distinct mechanism for neuronal excitation and synchrony and highlight a functional link between astrocytic glutamate and extrasynaptic NMDA receptors. 相似文献