全文获取类型
收费全文 | 939篇 |
免费 | 79篇 |
专业分类
1018篇 |
出版年
2024年 | 2篇 |
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 22篇 |
2020年 | 5篇 |
2019年 | 7篇 |
2018年 | 24篇 |
2017年 | 30篇 |
2016年 | 36篇 |
2015年 | 58篇 |
2014年 | 44篇 |
2013年 | 70篇 |
2012年 | 74篇 |
2011年 | 64篇 |
2010年 | 54篇 |
2009年 | 42篇 |
2008年 | 72篇 |
2007年 | 73篇 |
2006年 | 57篇 |
2005年 | 58篇 |
2004年 | 50篇 |
2003年 | 45篇 |
2002年 | 49篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 11篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1977年 | 1篇 |
1974年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有1018条查询结果,搜索用时 15 毫秒
1.
Cristina Cereda Emanuela Leoni Pamela Milani Orietta Pansarasa Giuliano Mazzini Stefania Guareschi Elena Alvisi Andrea Ghiroldi Luca Diamanti Stefano Bernuzzi Mauro Ceroni Emanuela Cova 《PloS one》2013,8(10)
Several lines of evidence support the hypothesis of a toxic role played by wild type SOD1 (WT-SOD1) in the pathogenesis of sporadic amyotrophic lateral sclerosis (SALS). In this study we investigated both distribution and expression profile of WT-SOD1 in leukocytes from 19 SALS patients and 17 healthy individuals. Immunofluorescence experiments by confocal microscopy showed that SOD1 accumulates in the nuclear compartment in a group of SALS subjects. These results were also confirmed by western blot carried out on soluble nuclear and cytoplasmic fractions, with increased nuclear SOD1 level (p<0.05). In addition, we observed the presence of cytoplasmic SOD1 aggregates in agreement with an increased amount of the protein recovered by the insoluble fraction. A further confirmation of the overall increased level of SOD1 has been obtained from single cells analysis using flow cytometry as cells from SALS patients showed an higher SOD1 protein content (p<0.05). These findings add further evidence to the hypothesis of an altered WT-SOD1 expression profile in peripheral blood mononuclear cells (PBMCs) from patients with ALS suggesting that WT-SOD1 species with different degrees of solubility could be involved in the pathogenesis of the disease. 相似文献
2.
Summary A female with chronic myelocytic leukemia (CML) in blastic phase (BP) showed a masked Ph chromosome that had originated by a translocation between chromosomes 8 and 22, with no obvious involvement of chromosome 9. A duplication of the masked Ph and trisomy 13 were present as additional anomalies. The karyotype on peripheral blood unstimulated cultures was 48,XX,t(8;22)(p12;q11),+13,+der(22) t(8;22)/47,XX,t(8;22)(p12;q11),+der(22)t(8;22). While the duplication of the Ph is a frequent finding in BP of CML, we did not find any other case in the literature with duplication of a masked Ph. In situ hybridization with c-abl and bcr probes showed that a 3 bcr sequence was translocated to the der(8) chromosome, while the c-abl oncogene was transposed to the masked Ph. 相似文献
3.
Binding of BiP to an assembly-defective protein in plant cells 总被引:5,自引:1,他引:4
Emanuela Pedrazzini Giovanna Giovinazzo Roberto Bollini Aldo Ceriotti Alessandro Vitale 《The Plant journal : for cell and molecular biology》1994,5(1):103-110
The binding protein (BiP) has been implicated as a mediator of protein folding and assembly in the endoplasmic reticulum of mammalian cells and has often been found in stable association with structurally defective proteins. To acquire information on the activity of BiP in plant cells, we have expressed in tobacco protoplasts the wild type form and an assembly-defective form of bean phaseolin. Phaseolin (PHSL) is a soluble, trimeric, storage glycoprotein co-translationally inserted into the lumen of the endoplasmic reticulum and then transported along the secretory pathway to the protein storage vacuoles. We have previously shown that a PHSL mutant in which the last 59 amino acids have been deleted (Δ363PHSL) is unable to form trimers and is retained in a pre-Golgi compartment when synthesized in Xenopus oocytes. When transiently expressed in tobacco leaf protoplasts, wild-type PHSL is correctly glycosylated and assembles efficiently and rapidly into trimers. Δ363PHSL is also correctly glycosylated but does not trimerize. Tobacco BiP and Δ363PHSL are co-immunoselected using either anti-PHSL or anti-BiP antibodies. Under the same conditions, co-immunoselection of BiP with wild-type PHSL is not detectable. The BiP bound to Δ363PHSL can be released by treatment of the complex with ATP, indicating that the binding is related to the proposed function of BiP in protein folding and assembly in the endoplasmic reticulum. These data indicate that BiP stably binds structurally defective proteins in plant cells. 相似文献
4.
Luigina Cellini Nerino Allocati Domenico Angelucci Teresa Iezzi Emanuela Di Campli Leonardo Marzio Benedetto Dainelli 《Microbiology and immunology》1994,38(11):843-850
An experimental rodent model was used to demonstrate the viability of the coccoid form of Helicobacter pylori. Concentrated suspensions were prepared for the two different morphologies: at 2 days incubation for the bacillary forms and at 20 days incubation for the “dormant” forms. The strains used for incubation were two fresh isolates from humans with duodenal ulceration, and two collection strains. Five hundred microliters of culture (OD550 = 5 Mc Farland) of Helicobacter pylori with bacillary (2-5×109 CFU/ml) and coccoid (0 CFU/ml) morphology were inoculated intragastrically in BALB/c mice. The gastric mucosa of the mice was colonized by Helicobacter pylori with the administration of fresh bacillary and coccoid cultures and not with the established cultures. Helicobacter pylori was isolated at 1 week after inoculation with the administration of fresh bacillary cultures, while fresh coccoid Helicobacter pylori was recovered in mice stomachs after 2 weeks of inoculation. After colonization, histopathologic changes occurred after 1 month from inoculation; all colonized mice showed a systemic antibody response to Helicobacter pylori. These results support the thesis of the viability of coccoid Helicobacter pylori non-culturable in vitro and confirm that concentrated bacterial suspensions are able to colonize and to produce gastric alterations in this suitable animal model. 相似文献
5.
Guano F Bernardi R Negri C Donzelli M Prosperi E Ricotti GA Scovassi AI 《Cell death and differentiation》1994,1(2):101-107
Zinc ions exert an inhibitory effect on Ca(2+)Mg(2+)-dependent endonuclease which is supposed to be responsible for the fragmentation of DNA during apoptosis. In the experimental system we used, that is HeLa cells treated with VP-16, the protection from internucleosomal DNA degradation is modulated by Zn concentration and appears to be dependent on the time after treatment. This effect does not prevent cell death or occurrence of apoptotic parameters, suggesting that DNA ladder appearance is not a crucial event in apoptosis. The activation of poly(ADP-ribose)polymerase following the administration of VP-16, is not observed in cells in which DNA fragmentation has been abolished by zinc, supporting the hypothesis that this event is regulated by the appearance of small-sized DNA fragments. 相似文献
6.
Carbonera Daniela; Rovati Laura; Guano Fulvio; Balestrazzi Alma 《Journal of experimental botany》1995,46(3):347-354
Topoisomerase II was partially purified from Daucus carota cellsby a procedure including ammonium sulphate fractionation, ion-exchange,and affinity chromatography steps. The type II enzyme, identifiedfor its ability to unknot knotted P4 DNA and decatenate Trypanosomacruzi kDNA, requires ATP and Mg2+ for activity. The unknottingactivity was sensitive to an inhibitor of the mammalian typeII enzyme, the drug VP16 (IC50 32 mmol m3), whereas inhibitorsof DNA gyrase showed a limited effect on activity. The SDS-PAGEanalysis of the dsDNA cellulose fraction revealed the presenceof four polypeptides of apparent molecular masses of 72, 71,34, and 33 kDa among which only a polypeptide of about 70 kDacrossreacted with antibodies against yeast topoisomerase II.Immunoprecipitation experiments with monoclonal antibodies tothe and ß isoforms of the human enzyme confirmedthe recognition of a polypeptide of 70 kDa. The sedimentationcoefficient (S) of the topoisomerase II in the phosphocellulosefraction, calculated by analytical glycerol gradient, was 6.1corresponding to a molecular mass of about 123 kDa. Resultssuggest the presence in carrot of a protein of molecular massof 70 kDa having the typical properties of an eukaryotic topoisomeraseII and carrying epitopes recognized by MoAbs to both human and ß enzymes. The 70 kDa polypeptide might then representthe monomer of a homodimer enzyme of 123 kDa. Key words: Daucus carota, topoisomerase II, immunoprecipitation 相似文献
7.
Hdmx recruitment into the nucleus by Hdm2 is essential for its ability to regulate p53 stability and transactivation. 总被引:4,自引:0,他引:4
8.
Cell cycle arrest by human cytomegalovirus 86-kDa IE2 protein resembles premature senescence 总被引:2,自引:0,他引:2 下载免费PDF全文
Noris E Zannetti C Demurtas A Sinclair J De Andrea M Gariglio M Landolfo S 《Journal of virology》2002,76(23):12135-12148
Primary human embryo lung fibroblasts and adult diploid fibroblasts infected by the human cytomegalovirus (HCMV) display beta-galactosidase (beta-Gal) activity at neutral pH (senescence-associated beta-Gal [SA-beta-Gal] activity) and overexpression of the plasminogen activator inhibitor type 1 (PAI-1) gene, two widely recognized markers of the process designated premature cell senescence. This activity is higher when cells are serum starved for 48 h before infection, a process that speeds and facilitates HCMV infection but that is insufficient by itself to induce senescence. Fibroblasts infected by HCMV do not incorporate bromodeoxyuridine, a prerequisite for the formal definition of senescence. At the molecular level, cells infected by HCMV, beside the accumulation of large amounts of the cell cycle regulators p53 and pRb, the latter in its hyperphosphorylated form, display a strong induction of the cyclin-dependent kinase inhibitor (cdki) p16(INK4a), a direct effector of the senescence phenotype in fibroblasts, and a decrease of the cdki p21(CIP1/WAF). Finally, a replicative senescence state in the early phases of infection significantly increased the number of cells permissive to virus infection and enhanced HCMV replication. HCMV infection assays carried out in the presence of phosphonoformic acid, which inhibits the virus DNA polymerase and the expression of downstream genes, indicated that immediate-early and/or early (alpha) genes are sufficient for the induction of SA-beta-Gal activity. When baculovirus vectors expressing HCMV IE1-72 or IE2-86 proteins were inoculated into fibroblasts, the increase of p16(INK4a) (observed predominantly with IE2-86) was similar to that observed with the whole virus, as was the induction of SA-beta-Gal activity, suggesting that the viral IE2 gene leads infected cells into senescence. Altogether our results demonstrate for the first time that HCMV, after arresting the cell cycle and inhibiting apoptosis, triggers the cellular senescence program, probably through the p16(INK4a) and p53 pathways. 相似文献
9.
Abstract The presence, in the North Adriatic sea and in the Chioggia and Marano lagoons, of Pseliodinium vaubanii a rare dinoflagellate species, is reported. Our results showed that Pseliodinium vaubanii is a very frequent and abundant species in these environments. 相似文献
10.
Emanuela Ursino Alessandra M. Albertini Giulia Fiorentino Paolo Gabrieli Viola Camilla Scoffone Angelica Pellegrini Giuliano Gasperi Alessandro Di Cosimo Giulia Barbieri 《Microbial biotechnology》2020,13(6):1972-1982
Aedes albopictus transmits several arboviral infections. In the absence of vaccines, control of mosquito populations is the only strategy to prevent vector-borne diseases. As part of the search for novel, biological and environmentally friendly strategies for vector control, the isolation of new bacterial species with mosquitocidal activity represents a promising approach. However, new bacterial isolates may be difficult to grow and genetically manipulate. To overcome these limits, here we set up a system allowing the expression of mosquitocidal bacterial toxins in the well-known genetic background of Bacillus subtilis. As a proof of this concept, the ability of B. subtilis to express individual or combinations of toxins of Bacillus thuringiensis israelensis (Bti) was studied. Different expression systems in which toxin gene expression was driven by IPTG-inducible, auto-inducible or toxin gene-specific promoters were developed. The larvicidal activity of the resulting B. subtilis strains against second-instar Ae. albopictus larvae allowed studying the activity of individual toxins or the synergistic interaction among Cry and Cyt toxins. The expression systems here presented lay the foundation for a better improved system to be used in the future to characterize the larvicidal activity of toxin genes from new environmental isolates. 相似文献