全文获取类型
收费全文 | 4436篇 |
免费 | 368篇 |
出版年
2023年 | 32篇 |
2022年 | 72篇 |
2021年 | 129篇 |
2020年 | 81篇 |
2019年 | 103篇 |
2018年 | 146篇 |
2017年 | 111篇 |
2016年 | 186篇 |
2015年 | 273篇 |
2014年 | 242篇 |
2013年 | 340篇 |
2012年 | 390篇 |
2011年 | 384篇 |
2010年 | 192篇 |
2009年 | 176篇 |
2008年 | 242篇 |
2007年 | 236篇 |
2006年 | 210篇 |
2005年 | 177篇 |
2004年 | 165篇 |
2003年 | 155篇 |
2002年 | 157篇 |
2001年 | 62篇 |
2000年 | 35篇 |
1999年 | 48篇 |
1998年 | 40篇 |
1997年 | 35篇 |
1996年 | 30篇 |
1995年 | 20篇 |
1994年 | 17篇 |
1993年 | 13篇 |
1992年 | 17篇 |
1991年 | 22篇 |
1990年 | 24篇 |
1989年 | 9篇 |
1988年 | 11篇 |
1987年 | 16篇 |
1986年 | 10篇 |
1985年 | 18篇 |
1984年 | 17篇 |
1983年 | 17篇 |
1982年 | 13篇 |
1981年 | 13篇 |
1979年 | 12篇 |
1975年 | 9篇 |
1974年 | 13篇 |
1973年 | 11篇 |
1971年 | 7篇 |
1968年 | 9篇 |
1966年 | 7篇 |
排序方式: 共有4804条查询结果,搜索用时 31 毫秒
121.
122.
Sara Chiarella Antonella De Cola Giovanni Luca Scaglione Erminia Carletti Vincenzo Graziano Daniela Barcaroli Carlo Lo Sterzo Adele Di Matteo Carmine Di Ilio Brunangelo Falini Alessandro Arcovito Vincenzo De Laurenzi Luca Federici 《Nucleic acids research》2013,41(5):3228-3239
Nucleophosmin (NPM1) is an abundant nucleolar protein implicated in ribosome maturation and export, centrosome duplication and response to stress stimuli. NPM1 is the most frequently mutated gene in acute myeloid leukemia. Mutations at the C-terminal domain led to variant proteins that aberrantly and stably translocate to the cytoplasm. We have previously shown that NPM1 C-terminal domain binds with high affinity G-quadruplex DNA. Here, we investigate the structural determinants of NPM1 nucleolar localization. We show that NPM1 interacts with several G-quadruplex regions found in ribosomal DNA, both in vitro and in vivo. Furthermore, the most common leukemic NPM1 variant completely loses this activity. This is the consequence of G-quadruplex–binding domain destabilization, as mutations aimed at refolding the leukemic variant also result in rescuing the G-quadruplex–binding activity and nucleolar localization. Finally, we show that treatment of cells with a G-quadruplex selective ligand results in wild-type NPM1 dislocation from nucleoli into nucleoplasm. In conclusion, this work establishes a direct correlation between NPM1 G-quadruplex binding at rDNA and its nucleolar localization, which is impaired in the acute myeloid leukemia-associated protein variants. 相似文献
123.
Marilena Carbone Theodora Zlateva Luca Quaroni 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
The pH of a biological system is a crucial determinant of the structures and reactivity of its components and cellular homeostasis of H+ is critical for cell viability. Control and monitoring of cellular acidity are highly desirable for the purpose of studying biochemical processes in vivo.Methods
The effect of photolysis of a caged strong acid, the ester 1-(2-nitrophenyl)-ethylhexadecyl sulfonate (HDNS) is used to cause a controlled drop in pH in single cells. An isolated cell is selected under the IR microscope, irradiated with near-UV light and monitored by FTIR.Results
We demonstrate the use of FTIR spectromicroscopy to monitor light-induced acidification of the cellular medium by measuring the increased concentration of CO2 and corresponding decrease of HCO3− in the cell and in the surrounding medium.Conclusions
We have demonstrated a method to control and accurately monitor the changes in pH of a cellular system by coupling a caged proton-releasing agent with FTIR spectromicroscopy detection. The overall implementation of photolysis and spectroscopic detection in a microscope optical configuration ensures single cell selectivity in both acidification and monitoring. We show the viability of monitoring of pH changes by FTIR spectromicroscopy with sensitivity comparable to that of glass electrodes, better than the existing methods for determining cell pH.General significance
Reporting the effect of small variations of cellular acidity provides a major improvement in the understanding of the interplay between molecular properties as assessed in vitro and cell physiology. 相似文献124.
Olga De Castro Antonietta Di Maio José Armando Lozada García Danilo Piacenti Mario Vázquez-Torres Paolo De Luca 《Annals of botany》2013,112(3):589-602
Background and Aims
Recent research on the history of Platanus reveals that hybridization phenomena occurred in the central American species. This study has two goals: to help resolve the evolutive puzzle of central American Platanus, and to test the potential of real-time polymerase chain reaction (PCR) for detecting ancient hybridization.Methods
Sequencing of a uniparental plastid DNA marker [psbA-trnH(GUG) intergenic spacer] and qualitative and quantitative single nucleotide polymorphism (SNP) genotyping of biparental nuclear ribosomal DNA (nrDNA) markers [LEAFY intron 2 (LFY-i2) and internal transcribed spacer 2 (ITS2)] were used.Key Results
Based on the SNP genotyping results, several Platanus accessions show the presence of hybridization/introgression, including some accessions of P. rzedowskii and of P. mexicana var. interior and one of P. mexicana var. mexicana from Oaxaca (= P. oaxacana). Based on haplotype analyses of the psbA-trnH spacer, five haplotypes were detected. The most common of these is present in taxa belonging to P. orientalis, P. racemosa sensu lato, some accessions of P. occidentalis sensu stricto (s.s.) from Texas, P. occidentalis var. palmeri, P. mexicana s.s. and P. rzedowskii. This is highly relevant to genetic relationships with the haplotypes present in P. occidentalis s.s. and P. mexicana var. interior.Conclusions
Hybridization and introgression events between lineages ancestral to modern central and eastern North American Platanus species occurred. Plastid haplotypes and qualitative and quantitative SNP genotyping provide information critical for understanding the complex history of Mexican Platanus. Compared with the usual molecular techniques of sub-cloning, sequencing and genotyping, real-time PCR assay is a quick and sensitive technique for analysing complex evolutionary patterns. 相似文献125.
Paolo Bianco Roger Barker Oliver Brüstle Elena Cattaneo Hans Clevers George Q Daley Michele De Luca Lawrence Goldstein Olle Lindvall Christine Mummery Clara Sattler de Sousa e Brito Austin Smith 《The EMBO journal》2013,32(11):1489-1495
At the time of writing, the Italian Parliament is debating a new law that would make it legal to practice an unproven stem cell treatment in public hospitals. The treatment, offered by a private non‐medical organization, may not be safe, lacks a rationale, and violates current national laws and European regulations. This case raises multiple concerns, most prominently the urgent need to protect patients who are severely ill, exposed to significant risks, and vulnerable to exploitation. The scientific community must consider the context—social, financial, medical, legal—in which stem cell science is currently situated and the need for stringent regulation. Additional concerns are emerging. These emanate from the novel climate, created within science itself, and stem cell science in particular, by the currently prevailing model of ‘translational medicine’. Only rigorous science and rigorous regulation can ensure translation of science into effective therapies rather than into ineffective market products, and mark, at the same time, the sharp distinction between the striving for new therapies and the deceit of patients. 相似文献
126.
Irene Pérez López Luca Cariolato Darko Maric Ludovic Gillet Hugues Abriel Dario Diviani 《Molecular and cellular biology》2013,33(15):2903-2917
In response to stress, the heart undergoes a remodeling process associated with cardiac hypertrophy that eventually leads to heart failure. A-kinase anchoring proteins (AKAPs) have been shown to coordinate numerous prohypertrophic signaling pathways in cultured cardiomyocytes. However, it remains to be established whether AKAP-based signaling complexes control cardiac hypertrophy and remodeling in vivo. In the current study, we show that AKAP-Lbc assembles a signaling complex composed of the kinases PKN, MLTK, MKK3, and p38α that mediates the activation of p38 in cardiomyocytes in response to stress signals. To address the role of this complex in cardiac remodeling, we generated transgenic mice displaying cardiomyocyte-specific overexpression of a molecular inhibitor of the interaction between AKAP-Lbc and the p38-activating module. Our results indicate that disruption of the AKAP-Lbc/p38 signaling complex inhibits compensatory cardiomyocyte hypertrophy in response to aortic banding-induced pressure overload and promotes early cardiac dysfunction associated with increased myocardial apoptosis, stress gene activation, and ventricular dilation. Attenuation of hypertrophy results from a reduced protein synthesis capacity, as indicated by decreased phosphorylation of 4E-binding protein 1 and ribosomal protein S6. These results indicate that AKAP-Lbc enhances p38-mediated hypertrophic signaling in the heart in response to abrupt increases in the afterload. 相似文献
127.
We apply the Blue Moon constrained Molecular Dynamics technique to study a particular case of molecular recognition, one of the main issues of modern molecular biology. We investigate the effects of mutation of interface residues on the binding strength of the dimeric protein superoxide dismutase from Photobacterium leiognathi. With our technique we produce a specific path describing the separation of the dimers and we calculate the effective mean force involved in the process. We apply the method to two mutants and compare the results with those obtained in an earlier calculation on the native enzyme. The method is sensitive to the mutations and allows us to establish a semi-quantitative hierarchy for the association strengths of the three enzymes. 相似文献
128.
Luca Madaro Fabrizio Antonangeli Annarita Favia Bianca Esposito Filippo Biamonte Marina Bouché Elio Ziparo Gigliola Sica Antonio Filippini Alessio D'Alessio 《Journal of cellular biochemistry》2013,114(8):1843-1851
Caveolin‐1 (CAV1) is the principal structural component of caveolae which functions as scaffolding protein for the integration of a variety of signaling pathways. In this study, we investigated the involvement of CAV1 in endothelial cell (EC) functions and show that siRNA‐induced CAV1 silencing in the human EC line EA.hy926 induces distinctive morphological changes, such as a marked increase in cell size and formation of stress fibers. Design‐based stereology was employed in this work to make unbiased quantification of morphometric properties such as volume, length, and surface of CAV1 silenced versus control cells. In addition, we showed that downregulation of CAV1 affects cell cycle progression at G1/S phase transition most likely by perturbation of AKT signaling. With the aim to assess the contribution of CAV1 to typical biological processes of EC, we report here that CAV1 targeting affects cell migration and matrix metalloproteinases (MMPs) activity, and reduces angiogenesis in response to VEGF, in vitro. Taken together our data suggest that the proper expression of CAV1 is important not only for maintaining the appropriate morphology and size of ECs but it might represent a prospective molecular target for studying key biological mechanisms such as senescence and tumorigenesis. J. Cell. Biochem. 114: 1843–1851, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
129.
Lorenzo Rossi Luca Sebastiani Roberto Tognetti Riccardo d’Andria Giovanni Morelli Paolo Cherubini 《Plant and Soil》2013,372(1-2):567-579
Background and Aims
Olive tree (Olea europaea L.) is a drought-tolerant tree species cultivated in Mediterranean-type environments. Although it is tolerant to drought, dry conditions decrease its productivity. A thorough analysis of the hydraulic architecture and wood anatomical plasticity, as well as of their physiological significance, is needed to understand how olive trees will adapt to the predicted increase in frequency and severity of drought in the Mediterranean region.Methods
Dendrochronological, stable isotopic (δ13C, δ18O) and wood anatomical analyses were applied to understand how different water availability can affect wood stem structure and function, in rainfed and irrigated at 100 % of crop evapotranspiration (ETc) olive trees in an experimental orchard close to Benevento (Italy) from 1992 to 2009.Results
Dendrochronological data indicate that cross-dating and synchronization of ring-width time series in olive tree is possible. After the start of irrigation, significantly more negative δ13C and lower δ18O values were recorded in irrigated trees indicating higher stomatal conductance and transpiration rates. Increased water balance induced the formation of a higher number of vessels with higher diameter.Conclusions
Water balance variations affected wood anatomy and isotopic composition. Anatomical analyses detected structural and functional adjustments in rainfed trees that produced more vessels with lower diameter to prevent cavitation. Isotopic analyses confirmed that irrigated trees continuously showed enhanced transpiration rates. 相似文献130.
Sébastien Besseau Franziska Kellner Arnaud Lanoue Antje M.K. Thamm Vonny Salim Bernd Schneider Fernando Geu-Flores René H?fer Grégory Guirimand Anthony Guihur Audrey Oudin Ga?lle Glevarec Emilien Foureau Nicolas Papon Marc Clastre Nathalie Giglioli-Guivarc’h Benoit St-Pierre Danièle Werck-Reichhart Vincent Burlat Vincenzo De Luca Sarah E. O’Connor Vincent Courdavault 《Plant physiology》2013,163(4):1792-1803