全文获取类型
收费全文 | 487篇 |
免费 | 31篇 |
出版年
2023年 | 1篇 |
2022年 | 6篇 |
2021年 | 7篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 16篇 |
2017年 | 7篇 |
2016年 | 21篇 |
2015年 | 30篇 |
2014年 | 32篇 |
2013年 | 42篇 |
2012年 | 62篇 |
2011年 | 40篇 |
2010年 | 28篇 |
2009年 | 25篇 |
2008年 | 38篇 |
2007年 | 30篇 |
2006年 | 26篇 |
2005年 | 27篇 |
2004年 | 12篇 |
2003年 | 21篇 |
2002年 | 12篇 |
2001年 | 2篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1994年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
排序方式: 共有518条查询结果,搜索用时 62 毫秒
11.
ángela María Sánchez-López Abdellatif Bahaji Nuria De Diego Marouane Baslam Jun Li Francisco José Mu?oz Goizeder Almagro Pablo García-Gómez Kinia Ameztoy Adriana Ricarte-Bermejo Ond?ej Novák Jan F. Humplík Luká? Spíchal Karel Dole?al Sergio Ciordia María Carmen Mena Rosana Navajas Edurne Baroja-Fernández Javier Pozueta-Romero 《Plant physiology》2016,172(3):1989-2001
12.
Rosana S Lopes Marcelo M Cardoso Arthur O Sampaio Mario Santos BarbosaJr Celice C Souza Michelle C da Silva Elane Magno N Ferreira Marco Aurelio M Freire Rafael Rodrigues Lima Walace Gomes-Leal 《Journal of biosciences》2016,41(3):381-394
Neuroblasts from the subventricular zone (SVZ) migrate to striatum following stroke, but most of them die in the ischaemic milieu and this can be related to exacerbated microglial activation. Here, we explored the effects of the non-steroidal anti-inflammatory indomethacin on microglial activation, neuronal preservation and neuroblast migration following experimental striatal stroke in adult rats. Animals were submitted to endothelin-1 (ET-1)-induced focal striatal ischaemia and were treated with indomethacin or sterile saline (i.p.) for 7 days, being perfused after 8 or 14 days. Immunohistochemistry was performed to assess neuronal loss (anti-NeuN), microglial activation (anti-Iba1, ED1) and migrating neuroblasts (anti-DCX) by counting NeuN, ED1 and DCX-positive cells in the ischaemic striatum or SVZ. Indomethacin treatment reduced microglia activation and the number of ED1+ cells in both 8 and 14 days post injury as compared with controls. There was an increase in the number of DCX+ cells in both SVZ and striatum at the same survival times. Moreover, there was a decrease in the number of NeuN+ cells in indomethacin-treated animals as compared with the control group at 8 days but not after 14 days post injury. Our results suggest that indomethacin treatment modulates microglia activation, contributing to increased neuroblast proliferation in the SVZ and migration to the ischaemic striatum following stroke. 相似文献
13.
14.
Jafelice RM de Barros LC Bassanezi RC Gomide F 《Bulletin of mathematical biology》2004,66(6):1597-1620
This paper introduces a model for the evolution of positive HIV population and manifestation of AIDS (acquired immunideficiency
syndrome). The focus is on the nature of the transference rate of HIV to AIDS. Expert knowledge indicates that the transference
rate is uncertain and depends strongly on the viral load and the CD4+ level of the infected individuals. Here, we suggest to view the transference rate as a fuzzy set of the viral load and
CD4+ level values. In this case the dynamic model results in a fuzzy model that preserves the biological meaning and nature
of the transference rate λ. Its behavior fits the natural history of HIV infection reported in the medical science domain. The paper also includes a
comparison between the fuzzy model and a classic Anderson’s model using data reported in the literature. 相似文献
15.
Krepsky N Rocha Ferreira RB Ferreira Nunes AP Casado Lins UG Costa e Silva Filho F de Mattos-Guaraldi AL Netto-dosSantos KR 《Current microbiology》2003,46(4):280-286
The cell surface hydrophobicity of 60 isolates and three reference strains of Staphylococcus epidermidis was assayed by means of bacterial aggregation in liquid broth, phosphate-buffered saline, and in ammonium sulfate, as well as by affinity of the bacteria to n-hexadecane and polystyrene surfaces. In order to better characterize the isolates, the influence of bacterial growth time and enzyme treatment on cell hydrophobicity and the analysis of the slime production were also investigated. The strains presented the following profiles when assayed by the ammonium sulfate aggregation test (SAT): SAT < 1M, SAT 1M - <2M, SAT 2M - <4M, and SAT >or=4M. When SAT < 1M, the strains showed positive results for most of the cell surface hydrophobicity tests. None of the strains belonging to the groups with SAT >or= 1M showed spontaneous aggregation (SA), auto-aggregation (AA), or glass adherence, albeit 32 (62.7%) strains were polystyrene adherent and 42 (82.3%) presented weak adherence to n-hexadecane (>20%). The best correlation of the results was found among the AA and glass adherence tests (100%), followed by SA/ glass adherence (98%) and SA/ AA test (98%). The polystyrene adherence test and microbial adherence to n-hexadecane test (MATH) showed 78% correlation. Proteinase K treatment reduced bacterial adherence to polystyrene, but did not influence the SAT values. Three distinct groups of strains were distinguished by the polystyrene micromethod and glass tube adherence assay: 0.0-0.4 O.D. group, including non-glass adherent isolates; 0.5-0.7 O.D. group, including strains with variable profiles (adherent or non-adherent); and 0.8-1.3 O.D. group, composed of glass-adherent strains. Evaluation by a single method seemed not to reliably determine the surface hydrophobicity characteristics of S. epidermidis clinical isolates. Auto-aggregation properties of the strains that adhered to glass seemed related to slime expression, rather than cell surface hydrophobicity. Data also suggested involvement of protein components in adherence to polystyrene, but not in auto-aggregation properties assayed by SAT. 相似文献
16.
17.
Bacteria communicate at high cell density through quorum sensing, however, there are no reports about this mechanism in archaea. The archaeon Natronococcus occultus produces an extracellular protease at the end of growth. Early production of protease activity was observed when a low density culture was incubated with late exponential conditioned medium suggesting the presence of factor(s) inducing this activity. Conditioned medium and ethyl acetate extracts corresponding to the transition from exponential to stationary phase showed a positive signal in Agrobacterium biosensor. We report the detection of potential autoinducer molecules of the acylated homoserine lactone type in the archaeon N. occultus. These molecules may be responsible for the production/activation of extracellular protease. 相似文献
18.
Feitosa Ldos S Cisalpino PS dos Santos MR Mortara RA Barros TF Morais FV Puccia R da Silveira JF de Camargo ZP 《Fungal genetics and biology : FG & B》2003,39(1):60-69
Pulsed field gel electrophoresis (PFGE) and DNA hybridization were used to establish and compare the electrophoretic karyotypes of 12 clinical and environmental Paracoccidioides brasiliensis isolates from different geographic areas. Gene mapping allowed the identification of synteny groups and the use of isolated whole chromosomal bands to probe chromoblots indicated the existence of repetitive sequences, contributing to a better understanding of the structure and organization of the fungus genome. This represents the first comparative mapping study among different isolates. The results are indicative of the existence of genetic differences among natural isolates. DNA content of DAPI-stained nuclei of each isolate was estimated by confocal microscopy. Comparison of the genome sizes estimated by PFGE with those calculated by microfluorometry indicated the possible existence of haploid and diploid (or aneuploid) isolates of the fungus. 相似文献
19.
In this study, passive Ca2+ binding was determined in ventricular homogenates (VH) from neonatal (4–6 days) and adult rats, as well as in digitonin-permeabilized adult ventricular myocytes. Ca2+ binding sites, both endogenous and exogenous (Indo-1 and BAPTA) were titrated. Sarcoplasmic reticulum and mitochondrial Ca2+ uptake were blocked by thapsigargin and Ru360, respectively. Free [Ca2+] ([Ca2+]F was measured with Indo-1 and bound Ca2+ ([Ca2+]B) was the difference between [Ca2+]F and total Ca2+. Apparent Ca2+ dissociation constants (Kd) for BAPTA and Indo-1 were increased by 10–20 mg VH protein/ml (from 0.35 to 0.92 μM for Indo-1 and from 0.20 to 0.76 μM for BAPTA) and also by ruthenium red in the case of Indo-1. Titration with successive CaCl2 additions (2.5–10 nmoles) yielded δ[Ca2+]B/δ[Ca2+]F for the sum of [Ca2+]B at all three classes of binding sites. From this function, the apparent number of endogenous sites (Ben) and their Kd (Ken) were determined. Similar Ken values were obtained in neonatal and adult VH, as well as in adult myocytes (0.68 ± 0.14 μM, 0.69 ± 0.13 μM and 0.53 ± 0.10 μM, respectively). However, Ben was significantly higher in adult myocytes than in adult VH (1.73 ± 0.35 versus 0.70 ± 0.12 nmol/mg protein, P < 0.01), which correspond to ∼300 and 213 μmol/l cytosol. This indicates that binding sites are more concentrated in myocytes than in other ventricular components and that Ben determined in VH underestimates cellular Ben by 29%. Although Ben values in nmol/mg protein were similar in adult and neonatal VH (0.69 ± 0.12), protein content was much higher in adult ventricle (125 ± 7 versus 80 ± 1 mg protein/g wet weight, P < 0.01). Expressing Ben per unit cell volume (accounting for fractional mitochondrial volume, and 29% dilution in homogenate), the passive Ca2+ binding capacity at high-affinity sites is ∼300 and 176 mmol/I cytosol in adult and neonatal rat ventricular myocytes, respectively. Additional estimates suggest that passive Ca2+ buffering capacity in rat ventricle increases markedly during the first two weeks of life and that adult levels are attained by the end of the first month. 相似文献
20.