全文获取类型
收费全文 | 235篇 |
免费 | 12篇 |
专业分类
247篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 9篇 |
2020年 | 3篇 |
2019年 | 11篇 |
2018年 | 9篇 |
2017年 | 8篇 |
2016年 | 11篇 |
2015年 | 11篇 |
2014年 | 17篇 |
2013年 | 14篇 |
2012年 | 20篇 |
2011年 | 21篇 |
2010年 | 8篇 |
2009年 | 6篇 |
2008年 | 13篇 |
2007年 | 11篇 |
2006年 | 8篇 |
2005年 | 9篇 |
2004年 | 1篇 |
2003年 | 10篇 |
2002年 | 9篇 |
2001年 | 7篇 |
2000年 | 5篇 |
1999年 | 8篇 |
1998年 | 2篇 |
1996年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1985年 | 1篇 |
1978年 | 1篇 |
1971年 | 2篇 |
1968年 | 1篇 |
排序方式: 共有247条查询结果,搜索用时 0 毫秒
51.
Tamia Souto Jessica L. Deichmann Cecilia Núñez Alfonso Alonso 《Biodiversity and Conservation》2014,23(5):1331-1337
Community-based conservation (CBC) projects represent one approach to biodiversity conservation when working with indigenous and local people. This method aims to achieve conservation and development goals simultaneously, however whether both types of goals can be met or whether competition between the two precludes success is an issue of much discussion. Conservation targets are one of the most important elements upon which a conservation project is built. We propose that one way to link biodiversity conservation with human development goals is to consider people’s needs and interests in the selection of the conservation target. Here, we present three categories of conservation targets that vary according to the origin of motivation that drives indigenous and local people to conserve the target. According to the type of target selected, the level of participation, integration of traditional ecological knowledge, level of external intervention and long-term sustainability will vary. We encourage conservation practitioners to understand the motivations that lead indigenous and local people to participate in conservation projects, and to develop and design CBC projects from these incentives. 相似文献
52.
Andréa Simone Siqueira de Queirós Simone Cristina Soares Brand?o Ana Lúcia Coutinho Domingues Liana Gon?alves Macedo Maira Souto Ourem Edmundo Pessoa Almeida Lopes 《PLoS neglected tropical diseases》2014,8(6)
Background
Portal hypertension is responsible for various complications in patients with schistosomiasis, among them intrapulmonary vascular dilations (IPVD). In cirrhotic patients the presence of IPVD is a sign of poor prognosis, but in patients with hepatosplenic schistosomiasis (HSS) there are no studies assessing the significance of this change. The aim of this study was to evaluate the occurrence of IPVD through 99mTc-MAA scintigraphy in patients with HSS and its relationship with clinical, laboratory, endoscopic and ultrasound parameters.Methods
Cross-sectional study evaluating 51 patients with HSS. Patients were diagnosed with IPVD when the brain uptake of 99mTc-MAA was higher than 6%. Subsequently, they were divided according to presence (G1) or absence (G2) of IPVD and variables were compared between groups.Results
Overall, 51 patients with mean age of 56±12 years were assessed. IPVD was observed in 31 patients (60%). There was no statistically significant differences between groups when clinical, laboratory and endoscopic parameters were compared. Regarding ultrasound parameters, the splenic vein diameter was smaller in G1 (0.9±0.3 cm) compared to G2 (1.2±0.4 cm), p = 0.029.Conclusion
In patients with HSS, the occurrence of IPVD by 99mTc-MAA scintigraphy was high and was associated with lower splenic vein diameter, which can be a mechanism of vascular protection against portal hypertension. However, more studies are needed to determine the clinical significance of the early diagnosis and natural evolution of IPVD in this population. 相似文献53.
54.
Ramos JM Costa e Silva ÁM Martins RM Souto FJ 《Memórias do Instituto Oswaldo Cruz》2011,106(5):632-634
Leprosy and hepatitis B virus (HBV) are highly endemic in some regions of the state of Mato Grosso, in central Brazil. The association of leprosy with HBV and hepatitis C virus (HCV) was assessed using a seroprevalence study and 191 leprosy outpatients were included. Demographic data and the clinical classification of leprosy were recorded. Evidence of previous HBV infection was present in 53 patients (27.7%, 95% confidence interval: 21.9-34.5) and two (1%) were HBsAg positive. Five (2.6%) had antibodies to HCV. The prevalence of previous exposure to HBV was higher than expected for an adult population in central Brazil. In contrast, the prevalence of anti-HCV antibodies was not much higher regarding the age range of participants. HBV markers were associated with a higher number of sex partners and the use of injections without proper sterilisation of the syringes. The number of HBV carriers was small, suggesting that there was no increased likelihood of chronification among these patients. 相似文献
55.
Certain heat shock proteins are regulated by steroid hormones and are associated with oestrogen receptor function in reproductive tissues, indicating that these proteins have a role during implantation, decidualization and placentation. In the present study, the expression of hsp25, hsp70 and oestrogen receptor alpha were examined by immunohistochemistry in oviducts from rats during neonatal development, the oestrous cycle and during early pregnancy. Oestrogen receptor alpha was the first protein observed in the neonatal oviduct, and its expression preceded that of hsp70 and hsp25. Although these heat shock proteins have been associated with the oestrogen receptor, this study showed that during early development of the oviduct, the receptor protein was not associated with the concomitant expression of hsp25 and hsp70. However, these heat shock proteins were expressed when oviductal cells became differentiated. In the adult oviduct, hsp70 was more abundant than hsp25, moreover, there were no significant modifications in expression of hsp25 during the oestrous cycle. In contrast, the expression of hsp70 was significantly higher in epithelial cells during dioestrus, when the maximum amount of oestrogen receptor alpha was also observed. Therefore, the present study shows that hsp70, but not hsp25, is an oviductal protein modulated by the oestrous cycle and that it is a protein marker for specific phases of the oestrous cycle. In addition, hsp70 was more responsive to the hormonal changes in the infundibulum and ampullar regions of the oviduct. During early pregnancy, hsp25 expression was downregulated (unlike in the endometrium), whereas hsp70 was relatively abundant in the oviduct. hsp70 was observed in all functional segments of the oviduct during pregnancy, indicating that in the oviduct, this protein is modulated by oestrogens and progesterone and possibly by other pregnancy-related hormones. 相似文献
56.
57.
Insulin recruits GLUT4 from an intracellular location to the plasma membrane in rat adipocytes. The process involves multiple intracellular compartments and multiple protein functions, details of which are largely unknown partly due to our inability to separate individual GLUT4 compartments. Here, by hypotonic lysis, differential centrifugation, and glycerol density gradient sedimentation, we separated intracellular GLUT4 compartments in rat adipocytes into three fractions: plasma membrane-containing fraction T and plasma membrane-free fractions H and L. The GLUT4 contents in fractions T, H, and L were approximately 25, 56, and 18% of total GLUT4, respectively, in basal adipocytes and 55, 42, and 3-4% in insulin-stimulated adipocytes. The plasma membrane GLUT4 contents estimated separately further revealed that intracellular GLUT4 in fraction T amounts to approximately 20% in both basal and insulin-stimulated adipocytes. Organelle-specific marker and membrane traffic-related protein distribution data suggested that intracellular GLUT4 in fraction T represents sorting endosomes, whereas GLUT4 in fractions H and L represents storage endosomes and exocytic vesicles, respectively. The subcellular fractionation without homogenization described here should be useful in identifying the role of the individual GLUT4 compartments and the associated proteins in insulin-induced GLUT4 recruitment in rat adipocytes. 相似文献
58.
Lucas Roberto Pereira Gomes Márcia Souto Couri Claudio José Barros de Carvalho 《Revista Brasileira de Entomologia》2018,62(1):51-56
Drepanocnemis Stein (Diptera, Muscidae) is a small genus of flies that occur in high altitudes in the Colombian Andes, Ecuador, Peru and Bolivia. Herein we describe Drepanocnemis aurifronssp. nov. from Cuzco, Peru, which is found from high (2904 m) to lower altitudes (707 m). An updated phylogeny, key to species and map of species’ distributions are provided, together with images and illustrations of the male and the female terminalia. 相似文献
59.
Pedro H. D. M. Prazeres Viviani M. Almeida Luiza Lousado Julia P. Andreotti Ana E. Paiva Gabryella S. P. Santos Patrick O. Azevedo Luanny Souto Gregório G. Almeida Renato Filev Akiva Mintz Ricardo Gonçalves Alexander Birbrair 《Cellular and molecular neurobiology》2018,38(4):777-782
Pericytes are defined by their anatomical location encircling blood vessels' walls with their long projections. The exact embryonic sources of cerebral pericytes remain poorly understood, especially because of their recently revealed diversity. Yamamoto et al. (Sci Rep 7(1):3855, 2017) using state-of-the-art techniques, including several transgenic mice models, reveal that a subpopulation of brain pericytes are derived from phagocytic macrophages during vascular development. This work highlights a new possible ancestor of brain pericytes. The emerging knowledge from this research may provide new approaches for the treatment of several neurodevelopmental disorders in the future. 相似文献
60.
Caio de Oliveira Gorgulho Silva José Antonio de Aquino Ribeiro Augusto Lopes Souto Patrícia Verardi Abdelnur Luís Roberto Batista Kelly Assis Rodrigues Nádia Skorupa Parachin Edivaldo Ximenes Ferreira Filho 《Bioenergy Research》2018,11(2):316-329
The aim of this study was to valorize the hemicellulose-rich liquid fraction (liquor) arising from hydrothermal pretreatment of sugarcane bagasse (SCB) through its utilization as an unconventional, soluble carbon source for the production of hemicellulases, namely xylanases and α-L-arabinofuranosidases (ABFases), by Aspergillus niger DCFS11. Through the use of factorial design, pretreatment conditions producing liquors optimized for either early- or late-phase enzyme production were identified. Subsequent deep characterization of liquor components using liquid chromatography and mass spectrometry was performed to identify compounds likely responsible for hemicellulase induction. SCB liquors arising from various pretreatment configurations induced up to 2- and 8.6-fold higher xylanase and ABFase production, respectively, by A. niger DCFS11 than raw SCB substrate owing to the strong inducing potential of arabinosylated xylooligosaccharides and free arabinose solubilized during pretreatment. Notably, unlike the severe pretreatment conditions required for maximum cellulose saccharification and ethanol yields during biomass conversion, low severity and low biomass loading are required if enzyme production from liquor is desired at early-phase growth with no additional detoxification steps. This suggests that for effective application in biorefineries, separate or multi-step processes would be required to optimize both hemicellulase production by A. niger DCFS11 and cellulose digestion. This work demonstrates the potential of hydrothermal pretreatment of lignocellulosic substrates as a tool to increase the production of enzymes by filamentous fungi. 相似文献