全文获取类型
收费全文 | 1806篇 |
免费 | 146篇 |
国内免费 | 1篇 |
出版年
2023年 | 10篇 |
2022年 | 12篇 |
2021年 | 44篇 |
2020年 | 28篇 |
2019年 | 40篇 |
2018年 | 55篇 |
2017年 | 33篇 |
2016年 | 46篇 |
2015年 | 89篇 |
2014年 | 84篇 |
2013年 | 119篇 |
2012年 | 109篇 |
2011年 | 143篇 |
2010年 | 92篇 |
2009年 | 73篇 |
2008年 | 96篇 |
2007年 | 125篇 |
2006年 | 101篇 |
2005年 | 90篇 |
2004年 | 94篇 |
2003年 | 75篇 |
2002年 | 72篇 |
2001年 | 18篇 |
2000年 | 19篇 |
1999年 | 26篇 |
1998年 | 20篇 |
1997年 | 14篇 |
1996年 | 12篇 |
1995年 | 6篇 |
1994年 | 10篇 |
1993年 | 7篇 |
1992年 | 9篇 |
1991年 | 13篇 |
1990年 | 9篇 |
1989年 | 17篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1985年 | 11篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 10篇 |
1980年 | 4篇 |
1979年 | 14篇 |
1978年 | 6篇 |
1977年 | 11篇 |
1976年 | 8篇 |
1974年 | 5篇 |
1973年 | 5篇 |
1966年 | 8篇 |
1965年 | 9篇 |
排序方式: 共有1953条查询结果,搜索用时 15 毫秒
61.
Stefania Parlato Roberto Bruni Paola Fragapane Debora Salerno Cinzia Marcantonio Paola Borghi Paola Tataseo Anna Rita Ciccaglione Carlo Presutti Giulia Romagnoli Irene Bozzoni Filippo Belardelli Lucia Gabriele 《PloS one》2013,8(8)
Type I interferon (IFN-I) have emerged as crucial mediators of cellular signals controlling DC differentiation and function. Human DC differentiated from monocytes in the presence of IFN-α (IFN-α DC) show a partially mature phenotype and a special capability of stimulating CD4+ T cell and cross-priming CD8+ T cells. Likewise, plasmacytoid DC (pDC) are blood DC highly specialized in the production of IFN-α in response to viruses and other danger signals, whose functional features may be shaped by IFN-I. Here, we investigated the molecular mechanisms stimulated by IFN-α in driving human monocyte-derived DC differentiation and performed parallel studies on peripheral unstimulated and IFN-α-treated pDC. A specific miRNA signature was induced in IFN-α DC and selected miRNAs, among which miR-23a and miR-125b, proved to be negatively associated with up-modulation of Blimp-1 occurring during IFN-α-driven DC differentiation. Of note, monocyte-derived IFN-α DC and in vitro IFN-α-treated pDC shared a restricted pattern of miRNAs regulating Blimp-1 expression as well as some similar phenotypic, molecular and functional hallmarks, supporting the existence of a potential relationship between these DC populations. On the whole, these data uncover a new role of Blimp-1 in human DC differentiation driven by IFN-α and identify Blimp-1 as an IFN-α-mediated key regulator potentially accounting for shared functional features between IFN-α DC and pDC. 相似文献
62.
Mayra Cuéllar-Cruz Gerardo Gutiérrez-Sánchez Everardo López-Romero Estela Ruiz-Baca Julio C. Villagómez-Castro Lucio Rodríguez-Sifuentes 《Central European Journal of Biology》2013,8(4):337-345
In the past two decades, Candida species have become the second leading cause of invasive mycosis in immunocompromised patients. In order to colonize their hosts, these microorganisms express adhesins and cell wall proteins that allow them to adhere and neutralize the reactive oxygen species produced by phagocytic cells during the respiratory burst. However, the precise mechanism by which Candida cell wall proteins change their expression in response to oxidative stress has not been described. In an attempt to understand this change in response to oxidative stress, in this study, three Candida species, namely, C. albicans, C. glabrata and C. krusei, were exposed to increasing concentrations of H2O2 and induced cell wall proteins were identified by two-dimensional gel electrophoresis and peptide mass fingerprinting. Sequence analysis of differential proteins led to the identification of two heat-shock proteins in C. albicans, two enolases in C. glabrata and one enolase in C. krusei. Enolases may be involved in the protection of pathogenic cells against oxidative stress as suggested by the decrease in their expression when they were exposed to high concentrations of H2O2. To our knowledge, this is the first demonstration that expression of these proteins changes in response to oxidative stress in different Candida species. This knowledge can eventually facilitate both an early diagnosis and a more efficient treatment of this mycosis. 相似文献
63.
Maria Hernandez-Trejo Gerardo Garcia-Rivas Alejandro Torres-Quintanilla Estibalitz Laresgoiti-Servitje 《PloS one》2016,11(11)
IntroductionIrisin is considered to be a myokine and adipokine that may also participate in reproductive functions, as it increases significantly throughout pregnancy. However, the regulation of circulating irisin and its relationship with other cytokines has not been assessed thus far in pregnant women and their offspring.ObjectiveThe aim of this study was to evaluate differences in irisin and cytokine concentrations between women at the end of pregnancy and their offspring, as well as the relationship between maternal and newborn irisin and maternal and newborn biomarkers.MethodsTwenty-eight mother/newborn pairs were included in this study. The following biomarkers were evaluated in maternal venous and arterial umbilical cord blood samples: irisin, 27 cytokine panel, total antioxidant capacity (TAC), total plasma protein, and free fatty acid concentration.ResultsThe newborns had significantly lower irisin concentrations compared to their mothers (p = 0.03), but this difference was present only in babies born from mothers without labor prior to cesarean section delivery (p = 0.01). No significant differences in maternal and newborn irisin concentrations were found between diabetic and non-diabetic mothers or between overweight/obese and normal weight mothers. A significant positive correlation was found between TAC level and irisin concentration in newborns. Maternal and newborn interleukin (IL)-1β, IL-1RA, IL-5, IL-7, and interferon gamma-induced protein (IP)-10 levels were significantly positively correlated with irisin concentrations in both study groups. In addition, maternal IL1β, IL-5, IL-7, and IP-10 levels positively predicted maternal irisin concentrations. Furthermore, arterial cord blood TAC and IL-1β and IL1-RA levels positively predicted newborn irisin concentrations. Multiple regression analyses showed that maternal IL-13 negatively predicted offspring irisin levels (p = 0.03) and that maternal IL-1β positively predicted newborn irisin concentrations (p = 0.046).ConclusionNo evidence was found that serum irisin concentrations in mothers at pregnancy termination or those of their newborns correlated with maternal body mass index, the presence of diabetes mellitus, or free fatty acid levels. However, the results of this study indicated that cytokines might predict irisin concentration in mothers and their offspring, although interactions between irisin levels during pregnancy and the newborn have not yet been fully elucidated. 相似文献
64.
Patterns of among‐ and within‐species variation in heterospecific pollen receipt: The importance of ecological generalization 下载免费PDF全文
65.
The nutrients animals ingest are allocated to serve different functions. We used contrasting C stable isotope signatures of dominant vegetation types in a North American subtropical desert to decipher how avian consumers allocate nutrients to fuel oxidative metabolism and to construct tissues. We conducted C stable isotope analysis of breath and feathers collected from nectarivores (hummingbirds) and of breath, plasma, and red blood cell samples collected from frugivores, granivores, and insectivores. Based on varying nutrient characteristics of food sources, we expected that for frugivores and granivores, CAM‐derived food (RCCAM) would have similar importance for oxidative metabolism and for tissue building, that RCCAM in nectarivores and insectivores would be more important for fueling metabolism than for generating tissues, and that (although low) RCCAM in insectivores would be higher for sustaining metabolism than for building tissues. Our predictions held true for nectarivores and granivores, but RCCAM use in tissue building was lower than expected in frugivores and higher than expected in insectivores. Our examination at the trophic guild, population, and individual levels showed that in general, nutrients used to sustain oxidative metabolism and tissue construction had a uniform isotopic origin. This finding suggests that the avian community under investigation does not route different food groups to fulfill different needs. However, we found some exceptions, indicating that birds can use different food sources for different functions, irrespective of trophic guild. 相似文献
66.
67.
Translating niche features: Modelling differential exposure of Argentine reptiles to global climate change 下载免费PDF全文
Javier Nori Débora L. Moreno Azócar Felix B. Cruz Marcelo F. Bonino Gerardo C. Leynaud 《Austral ecology》2016,41(4):367-375
Global climate change affects the distributions of ectotherms and may be the cause of several conservation problems, such as great displacement of climatic suitable spaces for species and, consequently, important reductions of the extent of liveable places, threatening the existence of many of them. Species exposure (and hence vulnerability) to global climate change is linked to features of their climatic niches (such as the relative position of the inhabited localities of each species in the climatic space), and therefore to characteristics of their geographic ranges (such as the extent of the distributions or altitudinal range inhabited by the species). In order to analyze the pattern of response of Argentine reptiles to global climate change, we ran phylogenetic generalized least squares models using species exposure to global climate change as a response variable, and (i) niche properties (breadth and position of the species in the climate space) and (ii) general features of the distribution of species (maximum latitude, altitudinal range, maximum elevation, distributional range and proximity to the most important dispersal barrier) as predictors. Our results suggest that the best way to explain climate change exposure is by combining breadth and position of climatic niche of the species or combining geographic features that are indicators of both niche characteristics. Our best model shows that in our study area, species with the narrowest distributional ranges that also inhabit the highest elevations are the most exposed to the effects of global climate change. In this sense, reptile species from Yungas, Puna and Andes ecoregions could be especially vulnerable to the effects of climate change. We believe that these types of models may represent an interesting tool for determining species and places particularly threatened by the effects of global climate change, which should be strongly considered in conservation planning. 相似文献
68.
Thea?Magrone Mauro?Galantino Nunzio?Di Bitonto Luisella?Borraccino Gerardo?Chiaromonte Emilio?JirilloEmail author 《Immunity & ageing : I & A》2016,13(1):18
Background
Chronic upper respiratory tract infections (cURTI) are very frequent illnesses which occur at any age of life. In elderly, cURTI are complicated by immunosenescence, with involvement of lung immune responsiveness.Results
In the present study, 51 elderly (age range: 66–86) and 51 young (age range 24–58) cURTI patients underwent a single cycle (two weeks) of inhalatory therapy with salt-bromide-iodine thermal water in the thermal station “Margherita di Savoia” (Margherita di Savoia, BAT, Italy). Peripheral blood serum cytokines and clinical assessment were performed before therapy (T0) and after six months (T1) and 12 months (T2) from inhalatory treatment. In both elderly and young patients, at baseline an increased release of T helper (h)1-related cytokines [interleukin (IL)-2 and interferon-γ] and of Th2-related cytokine (IL-4) was documented. Inhalatory treatment reduced the excessive secretion of all the above-cited cytokines. IL-10 values were above normality at all times considered in both groups of patients. In addition, an increase in IL-17 and IL-21 serum levels following therapy was observed in both groups of patients. Pro-inflammatory cytokine (IL-1β, IL-6, IL-8 and tumor necrosis factor-α) baseline values were lower than normal values at T0 in both elderly and young cURTI patients. Their levels increased following inhalatory treatment.Clinically, at T2 a dramatic reduction of frequency of upper respiratory tract infections was recorded in both groups of patients.Conclusion
Thermal water inhalation is able to modulate systemic immune response in elderly and young cURTI patients, thus reducing excessive production of Th1 and Th2-related cytokines, on the one hand. On the other hand, increased levels of IL-21 (an inducer of Th17 cells) and of IL-17 may be interpreted as a protective mechanism, which likely leads to neutrophil recruitment in cURTI patients. Also restoration of pro-inflammatory cytokine release following inhalatory therapy may result in microbe eradication. Quite importantly, the maintenance of high levels of IL-10 during the follow-up would suggest a consistent regulatory role of this cytokine in attenuating the pro-inflammatory arm of the immune response.69.
Barragán-Ocaña Alejandro Reyes-Ruiz Gerardo Olmos-Peña Samuel Gómez-Viquez Hortensia 《Transgenic research》2019,28(3-4):391-399
Transgenic Research - Transgenic crops have been the recipient of strong support as well as vigorously opposed opinions since their appearance. In any case, their growth throughout the world has... 相似文献
70.
Juan Francisco Cuellar-Sandoval Luis Daniel Ortega-Martínez Víctor Manuel Hernández-Velázquez Juan Francisco Cuellar-Zometa Gerardo Torres-García Hebert Jair Barrales-Cureño 《Biocontrol Science and Technology》2019,29(1):1-18
Isaria fumosorosea is an entomopathogenic fungus that is used as a control alternative for nymphs and adults of Bemisia tabaci. Currently there are some commercial products, however, in greenhouse or field, these do not reach the levels of control as in the laboratory because the viability of the spores decreases as a result of the conditions of application of these products in situ. The objective of this work is to implement, through agroecological data, a system of biotechnological traps based on I. fumosorosea to increase the control efficiency mainly of adults of B. tabaci in strawberry greenhouses. One way to quantify the degree of infestation of a crop is the use of yellow traps, likewise to determine the spatial distribution of adults. The Taylor method [(1984). Assessing and interpreting the spatial distributions of insect populations. Annual Reviews of Entomology, 29, 321–357) was used in five different strawberry cultivation models, finding aggregate and regular distributions. Finally, once the crop model with the highest degree of infestation was selected, the designed traps were tested and mortalities were obtained between 50% and 90% in both the laboratory and the greenhouse. The biotechnological traps based on I. fumosorosea both in the laboratory and in the greenhouse had statistically the same effect as those used under the traditional method used in the field that is aspersion; therefore, this alternative method of application can be a tool important for the biological control of this pest. 相似文献