全文获取类型
收费全文 | 780篇 |
免费 | 47篇 |
国内免费 | 79篇 |
专业分类
906篇 |
出版年
2024年 | 5篇 |
2023年 | 10篇 |
2022年 | 18篇 |
2021年 | 38篇 |
2020年 | 18篇 |
2019年 | 24篇 |
2018年 | 29篇 |
2017年 | 21篇 |
2016年 | 28篇 |
2015年 | 60篇 |
2014年 | 63篇 |
2013年 | 51篇 |
2012年 | 72篇 |
2011年 | 58篇 |
2010年 | 41篇 |
2009年 | 39篇 |
2008年 | 46篇 |
2007年 | 44篇 |
2006年 | 37篇 |
2005年 | 18篇 |
2004年 | 34篇 |
2003年 | 21篇 |
2002年 | 22篇 |
2001年 | 16篇 |
2000年 | 8篇 |
1999年 | 15篇 |
1998年 | 3篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1990年 | 2篇 |
1987年 | 3篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1965年 | 1篇 |
1935年 | 1篇 |
排序方式: 共有906条查询结果,搜索用时 15 毫秒
41.
Fabíula Francisca Abreu Ana Carla Araújo Souza Simone Aparecida Teixeira Antônio Garcia Soares Daiane Franco Teixeira Rosilene Calazans Soares 《Free radical research》2016,50(12):1350-1360
Introduction: Acute pancreatitis (AP) may be severe and cause hospitalization or death, and the available treatment is insufficient to control pancreatic inflammation and pain. Rutin is a natural flavonoid with the potential to treat AP via anti-inflammatory, antinociceptive, and antioxidant activities.Aim: This study investigated the beneficial effects of rutin on experimental AP induced by l-arginine administration in mice.Methods: The l-arginine-induced AP model was used in Swiss mice (n?=?6–8). Mice submitted to AP induction were treated with rutin (37.5, 75, or 150?mg kg?1, p.o.) or vehicle (saline) after 24, 36, 48, and 60?h of AP induction. Abdominal hyperalgesia, serum enzymes, interleukin (IL)-6 levels, pancreatic inflammatory parameters, malondialdehyde (MDA) levels, antioxidant enzyme activities, and 3-nitrotyrosine contents were measured 72?h after induction.Results: Mice submitted to l-arginine injections developed abdominal hyperalgesia and increased serum amylase, lipase, C-reactive protein and IL-6 concentrations; and increased pancreatic myeloperoxidase activity, edema index, MDA, and 3-nitrotyrosine contents. A marked decrease in catalase activity was observed in the pancreas without alterations of superoxide dismutase (SOD) activity compared with the control group. Rutin treatment significantly impaired all the parameters that were altered by AP induction, but increased catalase and SOD activities in the pancreas compared with the vehicle-treated group.Conclusion: Rutin treatment exerted a protective effect on l-arginine-induced AP by mechanisms involving the reduction of oxidative stress, which suggests that this flavonoid has a potential for future approaches designed for the management of AP. 相似文献
42.
Scoaris Dde O Colacite J Nakamura CV Ueda-Nakamura T de Abreu Filho BA Dias Filho BP 《Antonie van Leeuwenhoek》2008,93(1-2):111-122
Aeromonas isolates from tap water, mineral water, and artesian well water were investigated for their ability to produce different
potential virulence factors or markers such as hemolysins, cytotoxins, phospholipase, DNase, hydrophobicity and their ability
to adhere to epithelial cells and to abiotic surfaces. The susceptibility to antibiotics of Aeromonas isolates was also examined. Majority of the isolates displayed hemolytic activity against sheep erythrocytes, while only
7 of the 23 Aeromonas strains displayed DNase activity and 4 of the 23 Aeromonas strains tested were regarded as positive for phospholipase production. Most of the isolates showed cytotoxic activities in
culture filtrate dilutions at titer of 1/8 or lower. No general relation between the strain isolated and the ability to interact
with epithelial cells could be established. Using the bacterial adherence to hydrocarbons method, most of the strains were
classified as highly hydrophilic. All five Aeromonas jandaei strains isolates, 9 of the 12 Aeromonas sp strains and four of the five Aeromonas hydrophila were multidrug resistant. The most active antimicrobial was ciprofloxacin (susceptible in 100% of the isolates), and the
least active antibiotic was ampicillin (resistance in 92% of the isolates). The majority of the isolates tested were not killed
by chlorine at 1.2 mg/l. Whether the high tolerance to chlorine of Aeromonas isolates can be linked to greater virulence is not know. 相似文献
43.
De Robertis EM Wessely O Oelgeschläger M Brizuela B Pera E Larraín J Abreu J Bachiller D 《The International journal of developmental biology》2001,45(1):189-197
We review how studies on the first Spemann-Mangold organizer marker, the homeobox gene goosecoid, led to the discovery of secreted factors that pattern the vertebrate embryo. Microinjection of goosecoid mRNA formed secondary axes and recruited neighboring cells. These non-cell autonomous effects are mediated in part by the expression of secreted factors such as chordin, cerberus and Frzb-1. Unexpectedly, many of the molecules secreted by the Spemann-Mangold organizer turned out to be antagonists that bind growth factors in the extracellular space and prevent them from binding to their receptors. The case of chordin is reviewed in detail, for this molecule has provided biochemical insights into how patterning by Spemann's organizer can be regulated by diffusion and proteolytic control. The study of the BMP-binding repeats of Chordin, which are present in many extracellular proteins, may provide a new paradigm for how cell-cell signaling is regulated in the extracellular space not only in embryos, but also in adult tissues. 相似文献
44.
45.
Sugarcane (Saccharum X officinarum): A Reference Study for the Regulation of Genetically Modified Cultivars in Brazil 总被引:1,自引:0,他引:1
Cheavegatti-Gianotto A de Abreu HM Arruda P Bespalhok Filho JC Burnquist WL Creste S di Ciero L Ferro JA de Oliveira Figueira AV de Sousa Filgueiras T Grossi-de-Sá MD Guzzo EC Hoffmann HP de Andrade Landell MG Macedo N Matsuoka S de Castro Reinach F Romano E da Silva WJ de Castro Silva Filho M César Ulian E 《Tropical plant biology》2011,4(1):62-89
Global interest in sugarcane has increased significantly in recent years due to its economic impact on sustainable energy production. Sugarcane breeding and better agronomic practices have contributed to a huge increase in sugarcane yield in the last 30?years. Additional increases in sugarcane yield are expected to result from the use of biotechnology tools in the near future. Genetically modified (GM) sugarcane that incorporates genes to increase resistance to biotic and abiotic stresses could play a major role in achieving this goal. However, to bring GM sugarcane to the market, it is necessary to follow a regulatory process that will evaluate the environmental and health impacts of this crop. The regulatory review process is usually accomplished through a comparison of the biology and composition of the GM cultivar and a non-GM counterpart. This review intends to provide information on non-GM sugarcane biology, genetics, breeding, agronomic management, processing, products and byproducts, as well as the current technologies used to develop GM sugarcane, with the aim of assisting regulators in the decision-making process regarding the commercial release of GM sugarcane cultivars. 相似文献
46.
Fabio Roselet Dries Vandamme Milene Roselet Koenraad Muylaert Paulo Cesar Abreu 《Bioenergy Research》2017,10(2):427-437
This study investigated the effects of pH, salinity, biomass concentration, and algal organic matter (AOM) on the efficiency of four commercial cationic flocculants. The tannin-based biopolymers Tanfloc SG and SL and the polyacrylamide polymers Flopam FO 4800 SH and FO 4990 SH were tested for flocculation of two microalgae models, the freshwater Chlorella vulgaris and the marine Nannochloropsis oculata. Both biomass concentration and AOM presence affected all polymers evaluated, whereas salinity and pH affected only Flopam and Tanfloc, respectively. A restabilization effect due to overdosing was only observed for Flopam polymers and increasing Tanfloc dose resulted in improved efficiency. Flopam polymers showed a significant decrease in the maximum quantum yield of photosystem II as function of polymer dose for Chlorella, which supported the need for toxicological studies to assess the potential toxicity of Flopam. In overall, Tanfloc was not affected by salinity nor presented potential toxicity therefore being recommended for the flocculation of both freshwater and marine species. 相似文献
47.
Arantes JM Francisco AF de Abreu Vieira PM Silva M Araújo MS de Carvalho AT Pedrosa ML Carneiro CM Tafuri WL Martins-Filho OA Elói-Santos SM 《Experimental parasitology》2011,(4):401-408
Desferrioxamine (DFO) is a potent iron chelator that is also known to modulate inflammation and act as an efficient antioxidant under normal conditions and under oxidative stress. Many in vitro and in vivo studies have shown the efficacy of DFO in the treatment of viral, bacterial and protozoan infections. DFO is known to reduce the intensity of Trypanosoma cruzi infections in mice even during a course of therapy that is not effective in maintaining anaemia or low iron levels. To further clarify these findings, we investigated the action of DFO on mouse T. cruzi infection outcomes and the direct impact of DFO on parasites.Infected animals treated with DFO (5 mg/animal/day) for 35 days, beginning 14 days prior to infection, presented lower parasitemia and lower cumulative mortality rate. No significant effect was observed on iron metabolism markers, erythrograms, leukograms or lymphocyte subsets.In the rapid method for testing in vivo T. cruzi susceptibility, DFO also induced lower parasitemia.In regard to its direct impact on parasites, DFO slightly inhibited the growth of amastigotes and trypomastigotes in fibroblast culture. Trypan blue staining showed no effects of DFO on parasite viability, and only minor apoptosis in trypomastigotes was observed. Nevertheless, a clear decrease in parasite mobility was detected.In conclusion, the beneficial actions of DFO on mice T. cruzi infection seem to be independent of host iron metabolism and free of significant haematological side effects. Through direct action on the parasite, DFO has more effective trypanostatic than trypanocidal properties. 相似文献
48.
F. P. Lima A. B. Nobile D. Freitas Souza C. A. Siqueira C. A. Lemos B. Abreu‐Santos J. A. P. Santos 《Zeitschrift fur angewandte Ichthyologie》2017,33(3):600-603
Length–weight relationships (LWRs) for 35 freshwater fish species from the SP/RJ coastal basin in Brazil are presented in this paper. Fishes were captured between 2011 and 2015 on an irregular basis using electrofishing, sieves, trawl nets, cast nets and fish‐traps. In this study new LWRs are reported for 28 species, plus the total weight and length for 34 and nine species, respectively. The study provides new information on less‐studied species and can serve as a basis for management and conservation in this area. 相似文献
49.
50.
P V S Z Capriles A P M Dias T E M M Costa M B N Oliveira M V C Faria E G Moura B A L Abreu M Bernardo-Filho 《Cellular and molecular biology, including cyto-enzymology》2002,48(7):771-776
The use of eggplant has been suggested to treat different diseases. We studied the effect of eggplant extract on the labeling of red blood cells (RBC) and plasma proteins with technetium-99m (Tc-99m) and on biodistribution of sodium pertechnetate (Tc-99m) in rats. Blood was incubated with an eggplant extract (final concentrations 3.12 to 250.00 mg/ml) for 60 min. Then, stannous chloride (SnCl2) (0.06 or 1.2 microg/ml) and Tc-99m, as sodium pertechnetate, were added. Samples of RBC and plasma (P) were separated and also precipitated and soluble (SF) and insoluble (IF) fractions were isolated. The percent of radioactivity (%ATI) in the fractions was calculated. In the biodistribution study, Wistar rats were treated with eggplant extract (300 mg/ml) for 4 weeks, in drinking water. Tc-99m was administered in the rats, after 90 min they were sacrificed and organs and blood were isolated. When 0.06 microg/ml SnCl2 was used, eggplant extract: i/ inhibited the label of RBC (97.14 +/- 2.01 to 52.21 +/- 3.97%ATI), ii/ decreased the labeling in IF-P from 38.79 +/- 11.73 to 5.49 +/- 2.65%ATI, and iii/ diminished the labeling in IF-RBC from 90.04 +/- 2.65 to 46.17 +/- 9.49%ATI. This inhibitory effect was not observed with SnCl2 1.2 microg/ml. In the biodistribution study, the %ATI: i/ increased in the liver from 2.15 +/- 0.54 to 3.11 +/- 1.29 and ii/ in the other organs the Tc-99m uptake was not modified. The uptake of Tc-99m in red blood cells protein (IF-RBC) decreased from 66.62 +/- 19.67 to 31.66 +/- 8.84%. It is possible to suggest that some components of the eggplant extract present an oxidation power able to alter the fixation of the Tc-99m on the blood elements. Moreover, as eggplant is metabolized in the liver, this fact could justify the alteration of the uptake in this organ. 相似文献