全文获取类型
收费全文 | 463篇 |
免费 | 30篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 11篇 |
2020年 | 5篇 |
2019年 | 7篇 |
2018年 | 11篇 |
2017年 | 6篇 |
2016年 | 8篇 |
2015年 | 17篇 |
2014年 | 29篇 |
2013年 | 32篇 |
2012年 | 41篇 |
2011年 | 39篇 |
2010年 | 32篇 |
2009年 | 19篇 |
2008年 | 26篇 |
2007年 | 25篇 |
2006年 | 21篇 |
2005年 | 23篇 |
2004年 | 21篇 |
2003年 | 21篇 |
2002年 | 23篇 |
2001年 | 7篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 9篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1979年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有493条查询结果,搜索用时 15 毫秒
91.
Milan Řezáč Fulvio Gasparo Jiří Král Petr Heneberg 《Zoological Journal of the Linnean Society》2014,172(2):451-474
The spider genus Dysdera is a species‐rich clade of specialized woodlice predators, composed typically of complexes of sibling species. Here, we analyse the Dysdera ninnii complex, distinguishing three species that exhibit slight but constant differences in the morphology of their copulatory organs, and in their genetic background. We designate a neotype for D. ninnii and redescribe it. We consider Dysdera pavesii Thorell, 1873 to be a junior synonym of Dysdera ninnii Canestrini, 1868. In addition, we describe two new species ( D ysdera moravica sp. nov. and D ysdera microdonta sp. nov. ). All three species occur in the region of north‐eastern Italy, Slovenia, and north‐western Croatia. D ysdera moravica sp. nov. expanded to central Europe. The species occur allopatrically or parapatrically. All three species possess the same diploid number and X0 sex chromosome determination. In some individuals we found chromosome fusions, and such polymorphism is common in spiders with holokinetic chromosomes. The analysis of mitochondrial (cytochrome c oxidase subunit I, COI) and nuclear ribosomal (internal transcribed spacer 2, ITS2) DNA markers revealed two clades, one formed by D. ninnii and D . microdonta sp. nov. , and a second by D . moravica sp. nov. Species of the first clade are not well defined by DNA markers. We noticed only weak separation of maternally inherited COI, and even overlap of autosomally inherited ITS2 sequences. We suggest that either short speciation time, unfinished lineage sorting, or rare hybridization events caused this pattern. In one sample of D . microdonta sp. nov. we detected the coxA gene of a Rickettsia species, which is the first record of this parasitic bacteria from the spider family Dysderidae. D ysdera microdonta sp. nov. occurs at higher altitudes than D. ninnii, and their distribution ranges form a long contact zone. Remarkably, we did not record any overlap of the two distribution ranges, suggesting that the lack of a precopulatory interspecific barrier causes a loss of reproduction potential. We hypothesize that because of the unsolved interspecific barrier together with only tiny differences in morphology and COI sequences, and no differences in karyotypes and ITS2 sequences, the D. ninnii species complex is evolutionarily young. © 2014 The Linnean Society of London 相似文献
92.
93.
94.
Mazzei F Guarrera S Allione A Simonelli V Narciso L Barone F Minoprio A Ricceri F Funaro A D'Errico M Vogel U Matullo G Dogliotti E 《Mutation research》2011,718(1-2):62-67
Several lines of evidence suggest an association between oxidative DNA-damage repair capacity and cancer risk. In particular, a DNA-glycosylase assay for removal of 8-oxoguanine (8-oxoG) in peripheral blood mononuclear cells (PBMC) has been successfully applied to identify populations with increased risk for lung cancer and squamous cell carcinomas of head and neck. In order to verify whether EBV-transformed lymphoblastoid cell lines (LCL) are a suitable surrogate for PBMC in specific DNA-repair phenotypic assays, a validation trial was conducted. PBMC from 20 healthy subjects were collected and an aliquot was transformed with EBV to obtain LCL. The ability of cell-free extracts from both cell types to incise a 3'-fluorescently labelled duplex oligonucleotide containing a single 8-oxoG (OGG assay) was evaluated. Since this activity is mediated predominantly by OGG1, the OGG1 gene expression was also measured. 8-oxoG DNA-glycosylase activity and OGG1 expression were significantly higher (p<0.0001) in LCL than in PBMC. However, while this assay was shown to be robust and reproducible when used on PBMC (intra-assay CV=8%), a high intra-culture variability was observed with LCL (intra-culture CV=16.8%). Neither differences on OGG1 gene expression nor the cell-cycle distribution seemed to account for this variability. Inter-individual variability of OGG activity in PBMC and LCL was not associated with OGG1 gene expression. We have therefore established a non-radioactive cleavage assay that can be easily applied to measure OGG activity in human PBMC. The use of LCL for DNA-repair genotype-phenotype correlation studies seems to be inappropriate, at least with cell-free based functional assays. 相似文献
95.
Soldi M Sarto C Valsecchi C Magni F Proserpio V Ticozzi D Mocarelli P 《Proteomics》2005,5(10):2641-2647
Two-dimensional liquid chromatography separation (2-DL), based on chromatofocusing for first dimension and hydrophobicity for second, can be used as a complementary method to two-dimensional gel electrophoresis (2-DE). A platform now available, ProteomeLab PF 2D provided by Beckman Coulter, (Fullerton, CA, USA), assembles these methods in automation. This system was applied to resolve large numbers of urine proteins. Reproducibility and sensitivity in protein resolution were evaluated in this study using urines collected from male blood donors. About 1000 peaks were detected at a pH range of 4.0-8.5 by applying 1 mg of proteins. Furthermore, the same fractions showing peaks with high absorbance intensities in second dimension were collected and subjected to matrix-assisted laser desorption/ionization-time of flight/mass spectrometry analysis for identification. The results showed that the 2-DL provides high reproducibility of two-dimensional protein map, and lends fractions to subsequent mass spectrometry analysis without the further need for extraction or solubilization of samples as required for spots excised from 2-DE gels. In addition, this system also allows to separate particularly proteins with 40-9 kDa molecular weight. 相似文献
96.
97.
Fulvio Pupilli Francesco Damiani Elena Nenz Sergio Arcioni 《In vitro cellular & developmental biology. Plant》1992,28(4):167-171
Summary Nodes ofMedicago sativa, Lotus corniculatus, Lotus tenuis, andLotus pedunculatus were cultured on MS basal media with different growth regulators. InM. sativa each node produced one shoot and the apical dominance was unaffected by high levels of cytokinins, and subsequent cycles
of culture. Shoot development was stimulated by the presence ofN
6-isopentenyl-adenine in the culture medium and was dependent on the genotype of the explant. Shoot development was not affected
by the original position of the node on the plant nor by the plant age. Shoots rooted in MS medium gelled with starch and
containing 2 mg·liter−1 indol-3-acetic acid. In the threeLotus species, node culture was a more effective technique than inM. sativa. The number of shoots per node increased with the time of culture and with the presence of 0.05 mg·liter−1 of 6-benzylaminopurine. The highest number of shoots derived from one node was achieved inL. pedunculatus and inL. tenuis by culturing single nodes, whereas inL. corniculatus stem segments had to be totally covered by the medium for success. Rooting was easily achieved in MS medium with or without
auxins. 相似文献
98.
Chenglin Zhu Vanessa Faillace Fulvio Laus Marilena Bazzano Luca Laghi 《Metabolomics : Official journal of the Metabolomic Society》2018,14(8):106
Background
Metabolomics has been recognized as a powerful approach for disease screening. In order to highlight potential health issues in subjects, a key factor is the possibility to compare quantitatively the metabolome of their biofluids with reference values from healthy individuals. Such efforts towards the systematic characterization of the metabolome of biofluids in perfect health conditions, far from concluded for humans, have barely begun on horses.Objectives
The present work attempts, for the first time, to give reference quantitative values for the molecules mostly represented in the urine metabolome of horses at rest and under light training, as observable by 1H-NMR.Methods
The metabolome of ten trotter horses, four male and six female, ranging from 3 to 8 years of age, has been observed by 1H-NMR spectroscopy before and after three training sessions.Results
We could characterize and quantify 54 molecules in trotter horse urine, originated from diet, protein digestion, energy generation or gut-microbial co-metabolism.Conclusion
We were able to describe how gender, age and exercise affected their concentration, by means of a two steps protocol based on univariate and robust principal component analysis.99.
Selenium Utilization by GPX4 Is Required to Prevent Hydroperoxide-Induced Ferroptosis 总被引:1,自引:0,他引:1
Irina Ingold Carsten Berndt Sabine Schmitt Sebastian Doll Gereon Poschmann Katalin Buday Antonella Roveri Xiaoxiao Peng Florencio Porto Freitas Tobias Seibt Lisa Mehr Michaela Aichler Axel Walch Daniel Lamp Martin Jastroch Sayuri Miyamoto Wolfgang Wurst Fulvio Ursini Marcus Conrad 《Cell》2018,172(3):409-422.e21
100.
Oxidative events in neuronal and glial cell-enriched fractions of rat cerebral cortex 总被引:1,自引:0,他引:1
Carla Caf Carla Torri Laura Bertorelli Fulvio Tartara Flavio Tancioni Paolo Gaetani Riccardo Rodriguez Y Baena Fulvio Marzatico 《Free radical biology & medicine》1995,19(6):853-857
The aim of this work was to investigate how neurons and glial cells separated from rat brain cortex respond to “in vitro” oxidative stress induced by incubation of the cellular fractions in the presence of prooxidant mixtures; in addition, the endogenous enzymatic antioxidant capacity of the purified fractions was investigated. Neuronal and glial cell-enriched fractions were obtained from rat cerebral cortex following passages of the tissue through meshes and centrifugations. The following parameters were evaluated: antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSHPx), and glucose-6-phosphate dehydrogenase (G6PDH); lipid peroxidation products (TBARS) prior to (basal) and after (iron-stimulated) incubation with a mixture of iron and ascorbic acid; intracellular production of reactive oxygen species (ROS) using a fluorescent probe, dichlorofluorescin-diacetate, in basal, iron-stimulated, and menadione stimulated conditions. SOD and GSHPx activities showed no significant changes between neurons and glia, whereas CAT and G6PDH activities were found to be significantly lower in glia than in neurons. TBARS levels were significantly lower in the glial fraction than in neurons, both in basal and iron-stimulated conditions. ROS production showed no differences between neurons and glia in both basal and menadione-stimulated conditions. Iron-stimulation produced a marked increase in ROS production, limited to the neuronal fraction, with the glial values being similar to the basal ones. Our conclusion is that glia and neurons isolated from rat cerebral cortex show a similar pattern of the most important antioxidant enzymes and of their basal ROS production, whereas glia is more resistant in “oxidative stress” conditions. 相似文献