全文获取类型
收费全文 | 2637篇 |
免费 | 178篇 |
国内免费 | 1篇 |
专业分类
2816篇 |
出版年
2024年 | 3篇 |
2023年 | 31篇 |
2022年 | 54篇 |
2021年 | 118篇 |
2020年 | 76篇 |
2019年 | 98篇 |
2018年 | 106篇 |
2017年 | 111篇 |
2016年 | 134篇 |
2015年 | 178篇 |
2014年 | 199篇 |
2013年 | 237篇 |
2012年 | 261篇 |
2011年 | 210篇 |
2010年 | 130篇 |
2009年 | 100篇 |
2008年 | 141篇 |
2007年 | 131篇 |
2006年 | 121篇 |
2005年 | 83篇 |
2004年 | 82篇 |
2003年 | 69篇 |
2002年 | 52篇 |
2001年 | 12篇 |
2000年 | 6篇 |
1999年 | 9篇 |
1998年 | 10篇 |
1997年 | 6篇 |
1996年 | 8篇 |
1995年 | 3篇 |
1994年 | 8篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1977年 | 1篇 |
1975年 | 2篇 |
1970年 | 1篇 |
1968年 | 2篇 |
排序方式: 共有2816条查询结果,搜索用时 0 毫秒
1.
Rafael Ricci-Azevedo Aline Ferreira Oliveira Marina C. A. V. Conrado Fernanda Caroline Carvalho Maria Cristina Roque-Barreira 《PLoS neglected tropical diseases》2016,10(4)
ArtinM, a D-mannose binding lectin from Artocarpus heterophyllus, has immunomodulatory activities through its interaction with N-glycans of immune cells, culminating with the establishment of T helper type 1 (Th1) immunity. This interaction protects mice against intracellular pathogens, including Leishmania major and Leishmania amazonensis. ArtinM induces neutrophils activation, which is known to account for both resistance to pathogens and host tissue injury. Although exacerbated inflammation was not observed in ArtinM-treated animals, assessment of neutrophil responses to ArtinM is required to envisage its possible application to design a novel immunomodulatory agent based on carbohydrate recognition. Herein, we focus on the mechanisms through which neutrophils contribute to ArtinM-induced protection against Leishmania, without exacerbating inflammation. For this purpose, human neutrophils treated with ArtinM and infected with Leishmania major were analyzed together with untreated and uninfected controls, based on their ability to eliminate the parasite, release cytokines, degranulate, produce reactive oxygen species (ROS), form neutrophil extracellular traps (NETs) and change life span. We demonstrate that ArtinM-stimulated neutrophils enhanced L. major clearance and at least duplicated tumor necrosis factor (TNF) and interleukin-1beta (IL-1β) release; otherwise, transforming growth factor-beta (TGF-β) production was reduced by half. Furthermore, ROS production and cell degranulation were augmented. The life span of ArtinM-stimulated neutrophils decreased and they did not form NETs when infected with L. major. We postulate that the enhanced leishmanicidal ability of ArtinM-stimulated neutrophils is due to augmented release of inflammatory cytokines, ROS production, and cell degranulation, whereas host tissue integrity is favored by their shortened life span and the absence of NET formation. Our results reinforce the idea that ArtinM may be considered an appropriate molecular template for the construction of an efficient anti-infective agent. 相似文献
2.
R Casanueva G V Hillyer V Ramajo A Oleaga E Y Espinoza A Muro 《The Journal of parasitology》2001,87(3):697-700
Previous studies of ours have demonstrated that a recombinant protein (Fh15) related to fatty acid-binding proteins did not induce significant protection in rabbits challenged 2 or 4 wk postimmunization over nonimmunized controls. In the current study, rabbits were immunized with Fh15 and challenged with Fasciola hepatica metacercariae 12 and 20 wk later. In the current study in which longer lag periods for challenge infection after the second immunization were used, worm burden reductions compared to adjuvant controls were a significant 43% and 76%, respectively. Importantly, rabbits immunized with Fh15 had significant numbers of immature flukes, 66% in the 12-wk period and 84% in the 20-wk lag period as compared to controls. In addition, liver lesions were clearly diminished in the vaccinated rabbits. Enzyme-linked immunosorbent assay absorbance values showed that immunized rabbits developed high antibody levels to Fh15 from 8 wk after the first immunization and did not increase after challenge. These results suggest that a recombinant F. hepatica molecule related to fatty acid-binding proteins induces protective (worm burden reductions), anti-fecundity (immature flukes), and anti-pathology (less liver lesions) effects in rabbits and may serve as a model for the immunoprophylaxis of fascioliasis. 相似文献
3.
Antonio Campos-Neto Fernanda W. M. Lima Arnaldo F. B. Andrade 《The Journal of eukaryotic microbiology》1985,32(1):84-88
A rapid and simple method for the purification of amastigotes of Trypanosoma cruzi from spleens of infected mice is described. A protein A-Scpharose 4B immunoadsorbent column bound with antisera to epimastigotes of T. cruzi was used to purify the tissue forms of this parasite. Host cells and debris are not retained, and parasites can be eluted in high yields and purity. Studies of surface glycoproteins and glycolipids of the purified amastigotes with 18 lectins of various specificities revealed the presence on the parasites of receptors for N-acetylglucosamine, N-acetylgalactosamine, D-galactose, and D-mannose binding lectins. 相似文献
4.
5.
C. Carey O. Dunin-Borkowski F. Leon-Velarde D. Espinoza C. Monge 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1994,163(8):649-656
Oxygen consumption, air cell gases, hematology, blood gases and pH of Puna teal (Anas versicolor puna) embryos were measured at the altitude at which the eggs were laid (4150 m) in the Peruvian Andes. In contrast to the metabolic depression described by other studies on avian embryos incubated above 3700 m, O2 consumption of Puna teal embryos was higher than even that of some lowland avian embryos at equivalent body masses. Air cell O2 tensions dropped from about 80 toor in eggs with small embryos to about 45 toor in eggs containing a 14-g embryo; simultaneously air cell CO2 tension rose from virtually negligible amounts to around 26 torr. Arterial and venous O2 tensions (32–38 and 10–12 toor, respectively, in 12- to 14-g embryos) were lower than described previously in similarly-sized lowland wild avian embryos or chicken embryos incubated in shells with restricted gas exchange. The difference between air cell and arterial O2 tensions dropped significantly during incubation to a minimum of 11 torr, the lowest value recorded in any avian egg. Blood pH (mean 7.49) did not vary significantly during incubation. Hemoglobin concentration and hematocrits rose steadily throughout incubation to 11.5 g · 100 ml-1 and 39.9%, respectively, in 14-g embryos.Abbreviations PO2
partial pressure gradient of O2
- BM
body mass
-
D
diffusion coefficient
-
G
gas conductance (cm3·s-1·torr-1)
-
conductance to water vapor
- IP
internal pipping of embryos
-
P
ACO2
partial pressure of carbon dioxide in air cell
-
P
AO2
partial pressure of oxygen in air cell
-
P
aCO2
partial pressure of carbon dioxide in arterial blood
-
P
aCO2
partial pressure of oxygen in arteries
-
P
H
barometric pressure (torr)
-
PCO2
partial pressure of carbon dioxide
-
P
IO2
partial pressure in ambiant air
-
PO2
partial pressure of oxygen
-
P
VCO2
venous carbon dioxide partial pressure
-
P
VO2
mixed venous oxygen partial pressure
- SE
standard error
-
VO
2
oxygen consumption 相似文献
6.
7.
8.
Paulino Bambi Alan M. Tonin Renan de Souza Rezende Fernando Carvalho Vieira Fernanda Gabriela Graciano Miranda Luz Boyero José F. Gonçalves Júnior 《Biotropica》2023,55(1):40-52
Riparian forests play an important role in stream ecosystems, as they support biodiversity, reduce water erosion, and provide litter that fuels aquatic biota. However, they are affected by great array of anthropogenic threats (e.g., fire, logging, and organic pollution), which alter species composition and their physical structure. Although forest recovery after disturbance such as logging can take decades, the legacy of forest clear-cut logging on key processes in tropical riparian ecosystems is mostly unknown. Here, we investigated how litter inputs (leaves, twigs, and reproductive parts) and storage, key processes for carbon and nutrient recycling and for forest and stream biota, are influenced by riparian vegetation undergoing succession (after 28 years from logging) through the comparison of reference and logged forest sites in the Cerrado biome. Litterfall was overall similar between forest types, but litterfall of twigs was twofold higher at logged than reference sites. Similarly, litter inputs from the bank to the stream (i.e., lateral inputs) and streambed storage were 50–60% higher at logged than reference sites. The higher litterfall observed in logged forests could be related to higher proportion of tree species that are characteristic of primary and secondary successional stages, including fast-growing and liana species, which often are more productive and common in anthropogenic areas. Our results showed that the legacy impact of clear-cut logging, even if residual woody vegetation is maintained in riparian buffers, can shift the type, quantity, and seasonality of litter subsidies to tropical streams. This knowledge should be considered within the context of management and conservation of communities and ecosystem processes in the forest-stream interfaces. 相似文献
9.
Coelho-Rocha Nina Dias de Jesus Luís Cláudio Lima Barroso Fernanda Alvarenga Lima da Silva Tales Fernando Ferreira Enio Gonçalves José Eduardo dos Santos Martins Flaviano de Oliveira Carvalho Rodrigo Dias Barh Debmalya Azevedo Vasco Ariston de Carvalho 《Probiotics and antimicrobial proteins》2023,15(1):160-174
Probiotics and Antimicrobial Proteins - Beneficial effects of Lactiplantibacillus plantarum strains have been widely reported. Knowing that the effects of probiotic bacteria are strain-dependent,... 相似文献
10.