全文获取类型
收费全文 | 707篇 |
免费 | 43篇 |
出版年
2023年 | 6篇 |
2022年 | 13篇 |
2021年 | 32篇 |
2020年 | 29篇 |
2019年 | 28篇 |
2018年 | 34篇 |
2017年 | 20篇 |
2016年 | 47篇 |
2015年 | 39篇 |
2014年 | 49篇 |
2013年 | 60篇 |
2012年 | 68篇 |
2011年 | 47篇 |
2010年 | 27篇 |
2009年 | 17篇 |
2008年 | 29篇 |
2007年 | 36篇 |
2006年 | 17篇 |
2005年 | 27篇 |
2004年 | 20篇 |
2003年 | 9篇 |
2002年 | 23篇 |
2001年 | 11篇 |
2000年 | 11篇 |
1999年 | 13篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
排序方式: 共有750条查询结果,搜索用时 15 毫秒
121.
Tasca Carla I. Cardoso Luciana F. Martini Lúcia H. Ramírez Galo Souza Diogo O. 《Neurochemical research》1998,23(2):183-188
Metabotropic glutamate receptors (mGluRs) have been shown to modulate adenylate cyclase activity via G-proteins. In the present study we report similar results to the previously observed in the literature, showing that glutamate and the metabotropic agonists, 1S,3R-ACPD or quisqualate induced cAMP accumulation in hippocampal slices of young rats. Moreover, guanine nucleotides GTP, GDP or GMP, inhibited the glutamate-induced cAMP accumulation. By measuring LDH activity in the buffer surrounding the slices, we showed that the integrity of the slices was maintained, indicating that the effect of guanine nucleotides was extracellular. GMP, GDP-S or Gpp(NH)p abolished quisqualate-induced cAMP accumulation. GDP-S or Gpp(NH)p but not GMP inhibited 1S,3R-ACPD-induced cAMP accumulation. The response evoked by glutamate was also abolished by the mGluR antagonists: L-AP3 abolished glutamate-induced cAMP accumulation in a dose-dependent manner and MCPG was effective only at the 2 mM dose. DNQX was ineffective. We are reporting here, an inhibition induced by guanine nucleotides, via an extracellular site (s), similar to the observed with classical glutamate antagonists on a cellular response evoked by mGluR agonists. 相似文献
122.
123.
Priscila da Silva Delabona Deise Juliana Lima Diogo Robl Sarita Cândida Rabelo Cristiane Sanchez Farinas José Geraldo da Cruz Pradella 《Journal of industrial microbiology & biotechnology》2016,43(5):617-626
The use of glycerol obtained as an intermediate of the biodiesel manufacturing process as carbon source for microbial growth is a potential alternative strategy for the production of enzymes and other high-value bioproducts. This work evaluates the production of cellulase enzymes using glycerol for high cell density growth of Trichoderma harzianum followed by induction with a cellulosic material. Firstly, the influence of the carbon source used in the pre-culture step was investigated in terms of total protein secretion and fungal morphology. Enzymatic productivity was then determined for cultivation strategies using different types and concentrations of carbon source, as well as different feeding procedures (batch and fed-batch). The best strategy for cellulase production was then further studied on a larger scale using a stirred tank bioreactor. The proposed strategy for cellulase production, using glycerol to achieve high cell density growth followed by induction with pretreated sugarcane bagasse, achieved enzymatic activities up to 2.27 ± 0.37 FPU/mL, 106.40 ± 8.87 IU/mL, and 9.04 ± 0.39 IU/mL of cellulase, xylanase, and β-glucosidase, respectively. These values were 2 times higher when compared to the control experiments using glucose instead of glycerol. This novel strategy proved to be a promising approach for improving cellulolytic enzymes production, and could potentially contribute to adding value to biomass within the biofuels sector. 相似文献
124.
Carla I. Tasca Luciana F. Cardoso Deusa Vendite Diogo O. Souza 《Neurochemical research》1999,24(8):1067-1074
Binding properties of the subtypes of adenosine A2 receptors in membrane preparations and the effects of adenosine receptor ligands on cAMP accumulation in slices from the optic tectum of neonatal chicks have been investigated. [3H]2-[4-(2-p-carboxyethyl)phenylamino]-5'-N-ethylcarboxaminoadenosine (CGS 21680), a selective ligand for adenosine A2a receptors, did not bind to optic tectal membranes, as observed with rat striatal membranes. CGS 21680 also did not induce cyclic AMP accumulation in optic tectum slices. However, 5'-N-ethylcarboxamidoadenosine (NECA), 2-chloro-adenosine or adenosine induced a 2.5- to 3-fold increase on cyclic AMP accumulation in this preparation. [3H]NECA binds to fresh non-washed-membranes obtained from optic tectum of chicks, displaying one population of binding sites, which can be displaced by NECA, 8-phenyltheophylline, 2-chloro-adenosine, but is not affected by CGS 21680. The estimated KD value was 400.90 ± 80.50 nM and the Bmax was estimated to be 2.51 ± 0.54 pmol/mg protein. Guanine nucleotides, which modulate G-proteins activity intracellularly, are also involved in the inhibition of glutamate responses by acting extracellularly. Moreover, we have previously reported that guanine nucleotides potentiate, while glutamate inhibits, adenosine-induced cyclic AMP accumulation in slices from optic tectum of chicks. However, the guanine nucleotides, GMP or GppNHp and the metabotropic glutamate receptors agonist, 1S,3R-ACPD did not alter the [3H]NECA binding observed in fresh non-washed-membranes. Therefore, the adenosine A2 receptor found in the optic tectum must be the adenosine A2b receptor which is available only in fresh membrane preparations, and its not modulated by guanine nucleotides or glutamate analogs. 相似文献
125.
Adriana Fernanda K. Vizuete Matheus Mittmann Hennemann Carlos Alberto Gonçalves Diogo Losch de Oliveira 《Neurochemical research》2017,42(10):2730-2742
Epilepsy prevalence is high in infancy and in the elderly population. Lithium–pilocarpine is widely used to induce experimental animal models of epilepsy, leading to similar neurochemical and morphological alterations to those observed in temporal lobe epilepsy. As astrocytes have been implicated in epileptic disorders, we hypothesized that specific astroglial changes accompany and contribute to epileptogenesis. Herein, we evaluated time-dependent astroglial alterations in the hippocampus of young (27-day-old) rats at 1, 14 and 56 days after Li–pilocarpine-induced status epilepticus (SE), corresponding to different phases in this model of epilepsy. We determined specific markers of astroglial activation: GFAP, S100B, glutamine synthetase (GS), glutathione (GSH) content, aquaporin-4 (AQP-4) and potassium channel Kir 4.1; as well as epileptic behavioral, inflammatory and neurodegenerative changes. Phase-dependent signs of hippocampal astrogliosis were observed, as demonstrated by increments in GFAP, S100B and GS. Astrocyte dysfunction in the hippocampus was characterized, based on the decrease in GSH content, AQP-4 and Kir 4.1 channels. Degenerating neurons were identified by Fluoro-Jade C staining. We found a clear, early (at SE1) and persistent (at SE56) increase in cerebrospinal fluid (CSF) S100B levels. Additionally, serum S100B was found to decrease soon after SE induction, implicating a rapid-onset increase in the CSF/serum S100B ratio. However, serum S100B increased at SE14, possibly reflecting astroglial activation and/or long-term increase in cerebrovascular permeability. Moreover, we suggest that peripheral S100B levels may represent a useful marker for SE in young rats and for follow up during the chronic phases of this model of epilepsy. Together, results reinforce and extend the idea of astroglial involvement in epileptic disorders. 相似文献
126.
Júnia Rafael Mendonça Figueiredo Patrícia Duarte de Oliveira Paiva Michele Valquíria dos Reis Fernanda Carlota Nery Samantha de Menezes Campos Diogo Pedrosa Corrêa da Silva Renato Paiva 《Acta Physiologiae Plantarum》2017,39(7):147
Soil salinity is mainly caused by excessive use of fertilizers and the use of poor quality water, and adversely affected crop growth especially when grown in protected environments. Soil salinity causes salt stress in plants, which inhibits plant growth, leading to morphological, metabolic and physiological changes. Though it is a major problem occurs more frequently, there is less information on the behavior of calla lily (Zantedeschia aethiopica) under these conditions, and most studies are conducted with other species of the genus Zantesdeschia. Therefore, this study aimed to evaluate ecophysiological, biochemical and anatomical growth responses of calla lily plants to salt stress. Rhizomes were grown in trays containing coconut fiber as a substrate and treated with 0, 25, 50, 75 and 100 mM NaCl to induce stress. A decrease in plant height was observed, as well as in the number of tillers and leaves, main root length, fresh and dry matter of the shoot and root system. A reduction in photosynthetic rate, stomatal conductance and transpiration rate was observed at 60 days. However, after 90 days, the photosynthetic rate was unchanged, with increased stomatal conductance and transpiration rate for plants exposed to 75 mM NaCl. Salt stress caused a higher accumulation of carbohydrates in shoots and roots. Thus, high concentrations of NaCl affect the development of calla lily, indicating that this species is susceptible to salt stress. 相似文献
127.
Structure_threader: An improved method for automation and parallelization of programs structure,fastStructure and MavericK on multicore CPU systems
下载免费PDF全文
![点击此处可从《Molecular ecology resources》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Francisco Pina‐Martins Diogo N. Silva Joana Fino Octávio S. Paulo 《Molecular ecology resources》2017,17(6):e268-e274
Structure_threader is a program to parallelize multiple runs of genetic clustering software that does not make use of multithreading technology (structure , fastStructure and MavericK) on multicore computers. Our approach was benchmarked across multiple systems and displayed great speed improvements relative to the single‐threaded implementation, scaling very close to linearly with the number of physical cores used. Structure_threader was compared to previous software written for the same task—ParallelStructure and StrAuto and was proven to be the faster (up to 25% faster) wrapper under all tested scenarios. Furthermore, Structure_threader can perform several automatic and convenient operations, assisting the user in assessing the most biologically likely value of ‘K’ via implementations such as the “Evanno,” or “Thermodynamic Integration” tests and automatically draw the “meanQ” plots (static or interactive) for each value of K (or even combined plots). Structure_threader is written in python 3 and licensed under the GPLv3. It can be downloaded free of charge at https://github.com/StuntsPT/Structure_threader . 相似文献
128.
José Carlos Gonçalves Graça Diogo Maria Teresa Coelho Nieves Vidal Sara Amâncio 《In vitro cellular & developmental biology. Plant》2008,44(5):412-418
Endogenous levels of indole-3-acetic acid (IAA), indole-3-acetylaspartic acid (IAAsp) and indole-3-butyric acid (IBA) were
measured during the first 8 d of in vitro rooting of rootstock from the chestnut ‘M3’ hybrid by high performance liquid chromatography (HPLC). Rooting was induced
either by dipping the basal ends of the shoots into a 4.92-mM IBA solution for 1 min or by sub-culturing the shoots on solid
rooting medium supplemented with 14.8-μM IBA for 5 d. For root development, the induced shoots were transferred to auxin-free
solid medium. Auxins were measured in the apical and basal parts of the shoots by means of HPLC. Endogenous levels of IAA
and IAAsp were found to be greater in IBA-treated shoots than in control shoots. In extracts of the basal parts of the shoots,
the concentration of free IAA showed a significant peak 2 d after either root inductive method and a subsequent gradual decrease
for the remainder of the time course. The concentration of IAAsp peaked at day 6 in extracts of the basal parts of shoots
induced with 14.8-μM IBA for 5 d, whereas shoots induced by dipping showed an initial increase until day 2 and then remained
stable. In extracts from basal shoot portions induced by dipping, IBA concentration showed a transient peak at day 1 and a
plateau between day 2 and 4, in contrast to the profile of shoots induced on auxin-containing medium, which showed a significant
reduction between 4 and 6 d after transferred to auxin-free medium. All quantified auxins remained at a relatively low level,
virtually constant, in extracts from apical shoot portions, as well as in extracts from control non-rooting shoots. In conclusion,
the natural auxin IAA is the signal responsible for root induction, although it is driven by exogenous IBA independently of
the adding conditions. 相似文献
129.
Li JJ Wang H Li J Qu F Swartz SG Hernández AS Biller SA Robl JA Tino JA Slusarchyk D Seethala R Sleph P Yan M Grover G Flynn N Murphy BJ Gordon D 《Bioorganic & medicinal chemistry letters》2008,18(8):2536-2539
A novel series of N1 substituted tetrazole amides were prepared and showed to be potent growth hormone (GH) secretagogues. Among them, hydroxyl containing analog 31 displayed excellent in vivo activity by increasing plasma GH 10-fold in an anesthetized IV rat model. 相似文献
130.
Kerly Wollmeister Hofmann Artur Francisco Schumacher Schuh Jonas Saute Raquel Townsend Daniele Fricke Renata Leke Diogo O. Souza Luis Valmor Portela Márcia Lorena Fagundes Chaves Carlos R. M. Rieder 《Neurochemical research》2009,34(8):1401-1404
Several lines of evidence suggest that neuroimmune mechanisms may be involved in the neurodegenerative process of Parkinson’s
disease (PD). Interleukin-6 (IL-6) is increased in the nigrostriatal region and in the cerebrospinal fluid of patients with
PD. IL-6 serum level was evaluated in PD patients. The effects of levodopa treatment and disease severity on IL-6 were also
studied. The IL-6 levels were similar between PD patients (treated and not treated) and controls. However, there was a negative
correlation of IL-6 levels and the activities of daily living scale (P < 0.05), indicating that patients with more severe disease have higher levels of this cytokine. No correlation involving
levodopa treatment and IL-6 serum level was found. The results suggest that only marginal effects of IL-6 occur on the peripheral
immune system, and that the role of IL-6 and others neuroimmune factors needs to be well elucidated on PD. 相似文献