全文获取类型
收费全文 | 3248篇 |
免费 | 202篇 |
国内免费 | 2篇 |
出版年
2024年 | 4篇 |
2023年 | 30篇 |
2022年 | 20篇 |
2021年 | 36篇 |
2020年 | 43篇 |
2019年 | 42篇 |
2018年 | 99篇 |
2017年 | 92篇 |
2016年 | 108篇 |
2015年 | 205篇 |
2014年 | 189篇 |
2013年 | 259篇 |
2012年 | 329篇 |
2011年 | 345篇 |
2010年 | 185篇 |
2009年 | 135篇 |
2008年 | 218篇 |
2007年 | 198篇 |
2006年 | 182篇 |
2005年 | 161篇 |
2004年 | 136篇 |
2003年 | 121篇 |
2002年 | 122篇 |
2001年 | 23篇 |
2000年 | 21篇 |
1999年 | 12篇 |
1998年 | 18篇 |
1997年 | 16篇 |
1996年 | 8篇 |
1995年 | 16篇 |
1994年 | 5篇 |
1993年 | 11篇 |
1992年 | 4篇 |
1991年 | 8篇 |
1990年 | 6篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1975年 | 5篇 |
1973年 | 1篇 |
1969年 | 1篇 |
1952年 | 1篇 |
排序方式: 共有3452条查询结果,搜索用时 15 毫秒
991.
Covadonga Torre Jesús Agüero Cristina Gómez-Aix Miguel A. Aranda 《The Annals of applied biology》2020,176(3):158-169
The importance of seeds as virus vehicles for long-distance dissemination makes essential the availability of adequate methods of analysis to guarantee the quality of seed lots. To improve the repertoire of sensitive methods for seed diagnosis, we have developed quantitative real-time RT-PCR assays (RT-qPCR) based on the TaqMan technology to detect three viruses which are seed transmitted in cucurbits, namely, cucumber green mottle mosaic virus (CGMMV), squash mosaic virus (SqMV) and melon necrotic spot virus (MNSV), and compared these assays with DAS-ELISA, the main method used for virus detection in seeds. The estimated RT-qPCR limits of detection were 96, 97 and 740 RNA target molecules for CGMMV, SqMV and MNSV, respectively. The estimated RT-qPCR analytical sensitivity (highest dilution capable of generating a detectable amplification signal) ranged between 10 and 1 pg/μL for the three viruses. Using RT-qPCR, we could reliably detect a single SqMV- or CGMMV-contaminated seed among 999 uncontaminated seeds in a seed lot, and sensitivities were 1,000 and 10,000 times of those provided by DAS-ELISA for SqMV and CGMMV, respectively. Our RT-qPCR assays have proved to be highly suitable for the analysis of seed lots, and the possibility of their implementation into certification programme should be taken into consideration. 相似文献
992.
Gustavo Ortiz M. Carmen Martín Alfonso J. Carrillo-Muñoz M. Jesús Payá 《Revista iberoamericana de micología》2013,30(4):235-238
BackgroundMalassezia pachydermatis is part of the skin microbiota of dogs and cats. M. pachydermatis has been associated with external otitis and seborrhoeic dermatitis, reported more often in dogs than in cats. When the physical, chemical or immunological mechanisms of the skin are altered, M. pachydermatis could act as a pathogen. Thus, several virulence factors, such as the ability to produce esterase, lipase, lipoxygenase, protease, chondroitin sulphatase, and hyaluronidase, have been studied.AimsIn the present study, we aim to identify the phospholipase activity measured at pH 6.3, and the proteinase activity measured at pH 6.3 and pH 6.8 (pH from ears of dogs with external otitis) of M. pachydermatis strains isolated from dogs with and without external otitis.MethodsThe phospholipase activity was measured using a semi-quantitative method with egg yolk, and the proteinase activity with a semi-quantitative method using bovine serum albumin agar. The study was performed on 96 isolates of M. pachydermatis, 43 isolated from dogs without clinical symptoms of otitis, and 52 isolated from dogs with otitis.ResultsIn our study, 75.8% of the isolates showed phospholipase activity at pH 6.3, and 81 and 97.9% of them showed proteinase activity measured at pH 6.3 and 6.8, respectively. A higher phospholipase activity was detected in strains isolated from dogs with otitis. The proteinase activity was increased at a pH of 6.8 (97.9%) in comparison to a pH of 6.3 (81%).ConclusionsOur results suggest that the phospholipase activity may play an important role in the invasion of host tissues in chronic canine otitis cases. The proteinase activity results obtained in this study suggest that a reduction in the pH of the treatment may improve its efficacy in the resolution of M. pachydermatis otitis. 相似文献
993.
Gloria Andrea Silva-Castro Imane Uad Almudena Rivadeneyra Juan Ignacio Vilchez Daniel Martin-Ramos Jesús González-López 《Geomicrobiology journal》2013,30(9):840-850
This article presents a research study on carbonate formation in solid and liquid media by Thalassospira sp., Halomonas sp., Bacillus pumilus, and Pseudomonas grimontii, four bacterial strains isolated from sediments and deep seawater. As part of this study, we analyzed carbonic anhydrase activity, pH, adsorption of calcium and magnesium ions, and total organic and inorganic carbon. The geochemical program PHREEQC was also used to calculate the mineral saturation indexes in all the cultures. The minerals formed were studied with X-ray diffraction, X-ray dispersive energy microanalysis, and scanning electron microscopy. In addition, all four bacterial strains were found to induce carbonate precipitation and to have carbonic anhydrase activity. Sterile control experiments did not precipitate carbonate. In solid M1 and B4 media, all of the strains precipitated magnesium calcite, whereas in the liquid media, they precipitated different percentages of magnesium calcite, aragonite, and monohydrocalcite. In both cases, small amounts of amorphous precipitates were also produced. This article discusses carbonate formation and the possible role played by metabolic activity, bacterial surfaces and carbonic anhydrase in this process. Finally, the results obtained lead to a hypothesis regarding the importance of carbonate precipitation for the survival of bacteria populations in certain habitats. 相似文献
994.
Alvarado Pérez Yolanda Muro Urista Claudia Maciel Cerda Alfredo Álvarez Sánchez Jesús Riera Rodríguez Francisco 《International journal of peptide research and therapeutics》2019,25(2):681-689
International Journal of Peptide Research and Therapeutics - The proteolytic action from encapsulated Bacillus subtilis cells into polymeric system based in sodium alginate-chitosan-poly (ethylene... 相似文献
995.
Multiple myeloma (MM) is a hematological malignancy characterized by frequent chromosome abnormalities. However, the molecular basis for this genome instability remains unknown. Since both impaired and hyperactive double strand break (DSB) repair pathways can result in DNA rearrangements, we investigated the functionality of DSB repair in MM cells. Repair kinetics of ionizing-radiation (IR)-induced DSBs was similar in MM and normal control lymphoblastoid cell lines, as revealed by the comet assay. However, four out of seven MM cell lines analyzed exhibited a subset of persistent DSBs, marked by γ-H2AX and Rad51 foci that elicited a prolonged G2/M DNA damage checkpoint activation and hypersensitivity to IR, especially in the presence of checkpoint inhibitors. An analysis of the proteins involved in DSB repair in MM cells revealed upregulation of DNA-PKcs, Artemis and XRCC4, that participate in non-homologous end joining (NHEJ), and Rad51, involved in homologous recombination (HR). Accordingly, activity of both NHEJ and HR were elevated in MM cells compared to controls, as determined by in vivo functional assays. Interestingly, levels of proteins involved in a highly mutagenic, translocation-promoting, alternative NHEJ subpathway (Alt-NHEJ) were also increased in all MM cell lines, with the Alt-NHEJ protein DNA ligase IIIα, also overexpressed in several plasma cell samples isolated from MM patients. Overactivation of the Alt-NHEJ pathway was revealed in MM cells by larger deletions and higher sequence microhomology at repair junctions, which were reduced by chemical inhibition of the pathway. Taken together, our results uncover a deregulated DSB repair in MM that might underlie the characteristic genome instability of the disease, and could be therapeutically exploited. 相似文献
996.
997.
Alba Gómez-Hierro Eva Lambea David Giménez-Zaragoza Sandra López-Avilés Tula Yance-Chávez Marta Montserrat M. Jesús Pujol Oriol Bachs Rosa Aligue 《PloS one》2015,10(11)
Background
Calcium/calmodulin-dependent protein kinase kinase (CaMKK) is required for diverse cellular functions. Mammalian CaMKK activates CaMKs and also the evolutionarily-conserved AMP-activated protein kinase (AMPK). The fission yeast Schizosaccharomyces pombe CaMKK, Ssp1, is required for tolerance to limited glucose through the AMPK, Ssp2, and for the integration of cell growth and division through the SAD kinase Cdr2.Results
Here we report that Ssp1 controls the G2/M transition by regulating the activity of the CaMK Srk1. We show that inhibition of Cdc25 by Srk1 is regulated by Ssp1; and also that restoring growth polarity and actin localization of ssp1-deleted cells by removing the actin-monomer-binding protein, twinfilin, is sufficient to suppress the ssp1 phenotype.Conclusions
These findings demonstrate that entry into mitosis is mediated by a network of proteins, including the Ssp1 and Srk1 kinases. Ssp1 connects the network of components that ensures proper polarity and cell size with the network of proteins that regulates Cdk1-cyclin B activity, in which Srk1 plays an inhibitory role. 相似文献998.
999.
Romina P. Salinas Rodolfo M. Ortiz Flores Jesús S. Distel Milton O. Aguilera María I. Colombo Walter Berón 《PloS one》2015,10(12)
The GTPases belonging to the Rho family control the actin cytoskeleton rearrangements needed for particle internalization during phagocytosis. ROCK and mDia1 are downstream effectors of RhoA, a GTPase involved in that process. Coxiella burnetii, the etiologic agent of Q fever, is internalized by the host´s cells in an actin-dependent manner. Nevertheless, the molecular mechanism involved in this process has been poorly characterized. This work analyzes the role of different GTPases of the Rho family and some downstream effectors in the internalization of C. burnetii by phagocytic and non-phagocytic cells. The internalization of C. burnetii into HeLa and RAW cells was significantly inhibited when the cells were treated with Clostridium difficile Toxin B which irreversibly inactivates members of the Rho family. In addition, the internalization was reduced in HeLa cells that overexpressed the dominant negative mutants of RhoA, Rac1 or Cdc42 or that were knocked down for the Rho GTPases. The pharmacological inhibition or the knocking down of ROCK diminished bacterium internalization. Moreover, C. burnetii was less efficiently internalized in HeLa cells overexpressing mDia1-N1, a dominant negative mutant of mDia1, while the overexpression of the constitutively active mutant mDia1-ΔN3 increased bacteria uptake. Interestingly, when HeLa and RAW cells were infected, RhoA, Rac1 and mDia1 were recruited to membrane cell fractions. Our results suggest that the GTPases of the Rho family play an important role in C. burnetii phagocytosis in both HeLa and RAW cells. Additionally, we present evidence that ROCK and mDia1, which are downstream effectors of RhoA, are involved in that process. 相似文献
1000.
Mario A. Rodríguez-Pérez Nadia A. Fernández-Santos María E. Orozco-Algarra José A. Rodríguez-Atanacio Alfredo Domínguez-Vázquez Kristel B. Rodríguez-Morales Olga Real-Najarro Francisco G. Prado-Velasco Eddie W. Cupp Frank O. Richards Jr. Hassan K. Hassan Jesús F. González-Roldán Pablo A. Kuri-Morales Thomas R. Unnasch 《PLoS neglected tropical diseases》2015,9(7)