全文获取类型
收费全文 | 1421篇 |
免费 | 81篇 |
国内免费 | 2篇 |
专业分类
1504篇 |
出版年
2024年 | 4篇 |
2023年 | 11篇 |
2022年 | 33篇 |
2021年 | 80篇 |
2020年 | 38篇 |
2019年 | 37篇 |
2018年 | 44篇 |
2017年 | 37篇 |
2016年 | 58篇 |
2015年 | 95篇 |
2014年 | 90篇 |
2013年 | 111篇 |
2012年 | 122篇 |
2011年 | 117篇 |
2010年 | 65篇 |
2009年 | 54篇 |
2008年 | 59篇 |
2007年 | 69篇 |
2006年 | 45篇 |
2005年 | 49篇 |
2004年 | 47篇 |
2003年 | 52篇 |
2002年 | 35篇 |
2001年 | 18篇 |
2000年 | 12篇 |
1999年 | 9篇 |
1998年 | 16篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1975年 | 3篇 |
1973年 | 2篇 |
1971年 | 4篇 |
1970年 | 5篇 |
1969年 | 2篇 |
排序方式: 共有1504条查询结果,搜索用时 15 毫秒
51.
Transgenic cotton expressing Cry10Aa toxin confers high resistance to the cotton boll weevil 下载免费PDF全文
Thuanne Pires Ribeiro Fabricio Barbosa Monteiro Arraes Isabela Tristan Lourenço‐Tessutti Marilia Santos Silva Maria Eugênia Lisei‐de‐Sá Wagner Alexandre Lucena Leonardo Lima Pepino Macedo Janaina Nascimento Lima Regina Maria Santos Amorim Sinara Artico Márcio Alves‐Ferreira Maria Cristina Mattar Silva Maria Fatima Grossi‐de‐Sa 《Plant biotechnology journal》2017,15(8):997-1009
52.
53.
Diego V. Beckmann Fabiano B. Carvalho Cinthia M. Mazzanti Rosmarini P. dos Santos Amanda O. Andrades Graciane Aiello Angel Rippilinger Dominguita L. Graça Fátima H. Abdalla Lizielle S. Oliveira Jessié M. Gutierres Maria Rosa C. Schetinger Alexandre Mazzanti 《Life sciences》2014
Aim
The purpose of this study was to investigate whether the flavonoid quercetin can prevent alterations in the behavioral tests and of cholinergic neurotransmission in rats submitted to the ethidium bromide (EB) experimental demyelination model during events of demyelination and remyelination.Main methods
Wistar rats were randomly distributed into four groups (20 animals per group): Control (pontine saline injection and treatment with ethanol), Querc (pontine saline injection and treatment with quercetin), EB (pontine 0.1% EB injection and treatment with ethanol), and EB + Querc (pontine 0.1% EB injection and treatment with quercetin). The groups Querc and Querc + EB were treated once daily with quercetin (50 mg/kg) diluted in 25% ethanol solution (1 ml/kg) and the animals of the control and EB groups were treated once daily with 25% ethanol solution (1 ml/kg). Two stages were observed: phase of demyelination (peak on day 7) and phase of remyelination (peak on day 21 post-injection). Behavioral tests (beam walking, foot fault and inclined plane test), acetylcholinesterase (AChE) activity and lipid peroxidation in pons, cerebellum, hippocampus, hypothalamus, striatum and cerebral cortex were measured.Key findings
The quercetin promoted earlier locomotor recovery, suggesting that there was demyelination prevention or further remyelination velocity as well as it was able to prevent the inhibition of AChE activity and the increase of lipidic peroxidation, suggesting that this compound can protect cholinergic neurotransmission.Significance
These results may contribute to a better understanding of the neuroprotective role of quercetin and the importance of an antioxidant diet in humans to provide benefits in neurodegenerative diseases such as MS. 相似文献54.
Sergey Malchenko Jianping Xie Maria de Fatima Bonaldo Elio F. Vanin Bula J. Bhattacharyya Abdelhak Belmadani Guifa Xi Vasily Galat William Goossens Richard E.B. Seftor Tadanori Tomita John Crispino Richard J. Miller Martha C. Bohn Mary J.C. Hendrix Marcelo B. Soares 《Gene》2014
In vitro neural differentiation of human embryonic stem cells (hESCs) is an advantageous system for studying early neural development. The process of early neural differentiation in hESCs begins by initiation of primitive neuroectoderm, which is manifested by rosette formation, with consecutive differentiation into neural progenitors and early glial-like cells. In this study, we examined the involvement of early neural markers – OTX2, PAX6, Sox1, Nestin, NR2F1, NR2F2, and IRX2 – in the onset of rosette formation, during spontaneous neural differentiation of hESC and human induced pluripotent stem cell (hiPSC) colonies. This is in contrast to the conventional way of studying rosette formation, which involves induction of neuronal differentiation and the utilization of embryoid bodies. Here we show that OTX2 is highly expressed at the onset of rosette formation, when rosettes comprise no more than 3–5 cells, and that its expression precedes that of established markers of early neuronal differentiation. Importantly, the rise of OTX2 expression in these cells coincides with the down-regulation of the pluripotency marker OCT4. Lastly, we show that cells derived from rosettes that emerge during spontaneous differentiation of hESCs or hiPSCs are capable of differentiating into dopaminergic neurons in vitro, and into mature-appearing pyramidal and serotonergic neurons weeks after being injected into the motor cortex of NOD-SCID mice. 相似文献
55.
Applications of IDA in, for example, immobilized metal ion affinity chromatography for purification of His-tagged proteins are well recognized. The use of IDA as an efficient chelating adsorbent for environmental separations, that is, for the capture of heavy metals, is not studied. Adsorbents based on supermacroporous gels (cryogels) bearing metal chelating functionalities (IDA residues and ligand derived from derivatization of epoxy-cryogel with tris(2-aminoethyl)amine followed by the treatment with bromoacetic acid (defined as TBA ligand)) have been prepared and evaluated on capture of heavy metal ions. The cryogels were prepared in plastic carriers, resulting in desired mechanical stability and named as macroporous gel particles (MGPs). Sorption and desorption experiments for different metals (Cu2+, Zn2+, Cd2+, and Ni2+ with IDA adsorbent and Cu2+ and Zn2+ with TBA adsorbent) were carried out in batch and monolithic modes, respectively. Obtained capacities with Cu2+ were 74 μmol/mL (TBA) and 19 μmol/mL gel (IDA). The metal removal was higher for pH values between pH 3 and 5. Both adsorbents showed improved sorption at lower temperatures (10°C) than at higher (40°C) and the adsorption significantly dropped for the TBA adsorbent and Zn2+ at 40°C. Desorption of Cu2+ by using 1 M HCl and 0.1 M EDTA was successful for the IDA adsorbent whereas the desorption with the TBA adsorbent needs further attention. The result of this work has demonstrated that MGPs are potential treatment alternatives within the field of environmental separations and the removal of heavy metals from water effluents. 相似文献
56.
Calvete JJ Sanz L Pérez A Borges A Vargas AM Lomonte B Angulo Y Gutiérrez JM Chalkidis HM Mourão RH Furtado MF Moura-Da-Silva AM 《Journal of Proteomics》2011,74(4):510-527
We describe two geographically differentiated venom phenotypes across the wide distribution range of Bothrops atrox, from the Colombian Magdalena Medio Valley through Puerto Ayacucho and El Paují, in the Venezuelan States of Amazonas and Orinoquia, respectively, and S?o Bento in the Brazilian State of Maranh?o. Colombian and Venezuelan venoms show an ontogenetic toxin profile phenotype whereas Brazilian venoms exhibit paedomorphic phenotypes. Venoms from each of the 16 localities sampled contain both population-specific toxins and proteins shared by neighboring B. atrox populations. Mapping the molecular similarity between conspecific populations onto a physical map of B. atrox range provides clues for tracing dispersal routes that account for the current biogeographic distribution of the species. The proteomic pattern is consistent with a model of southeast and southwest dispersal and allopatric fragmentation northern of the Amazon Basin, and trans-Amazonian expansion through the Andean Corridor and across the Amazon river between Monte Alegre and Santarém. An antivenomic approach applied to assess the efficacy towards B. atrox venoms of two antivenoms raised in Costa Rica and Brazil using Bothrops venoms different than B. atrox in the immunization mixtures showed that both antivenoms immunodepleted very efficiently the major toxins (PIII-SVMPs, serine proteinases, CRISP, LAO) of paedomorphic venoms from Puerto Ayacucho (Venezuelan Amazonia) through S?o Bento, but had impaired reactivity towards PLA(2) and P-I SVMP molecules abundantly present in ontogenetic venoms. The degree of immunodepletion achieved suggests that each of these antivenoms may be effective against envenomations by paedomorphic, and some ontogenetic, B. atrox venoms. 相似文献
57.
58.
59.
60.
Sherihan El-sayed Kamel Metwally Abdalla A. El-Shanawani Lobna M. Abdel-Aziz Ahmed A. El-Rashedy Mahmoud E.S. Soliman Luca Quattrini Vito Coviello Concettina la Motta 《Bioorganic & medicinal chemistry letters》2017,27(20):4760-4764
A series of quinazolinone-based rhodanine-3-acetic acids was synthesized and tested for in vitro aldose reductase inhibitory activity. All the target compounds displayed nanomolar activity against the target enzyme. Compounds 3a, 3b, and 3e exhibited almost 3-fold higher activity as compared to the only marketed reference drug epalrestat. Structure-activity relationship studies indicated that bulky substituents at the 3-phenyl ring of the quinazolinone moiety are generally not tolerated in the active site of the enzyme. Insertion of a methoxy group on the central benzylidene ring was found to have a variable effect on ALR-2 activity depending on the nature of peripheral quinazolinone ring substituents. Removal of the acetic acid moiety led to inactive or weakly active target compounds. Docking and molecular dynamic simulations of the most active rhodanine-3-acetic acid derivatives were also carried out, to provide the basis for further structure-guided design of novel inhibitors. 相似文献