全文获取类型
收费全文 | 4074篇 |
免费 | 238篇 |
国内免费 | 2篇 |
出版年
2024年 | 1篇 |
2023年 | 34篇 |
2022年 | 54篇 |
2021年 | 117篇 |
2020年 | 99篇 |
2019年 | 107篇 |
2018年 | 102篇 |
2017年 | 112篇 |
2016年 | 202篇 |
2015年 | 234篇 |
2014年 | 231篇 |
2013年 | 314篇 |
2012年 | 363篇 |
2011年 | 335篇 |
2010年 | 239篇 |
2009年 | 174篇 |
2008年 | 254篇 |
2007年 | 256篇 |
2006年 | 216篇 |
2005年 | 192篇 |
2004年 | 147篇 |
2003年 | 154篇 |
2002年 | 132篇 |
2001年 | 23篇 |
2000年 | 28篇 |
1999年 | 25篇 |
1998年 | 34篇 |
1997年 | 21篇 |
1996年 | 20篇 |
1995年 | 15篇 |
1994年 | 13篇 |
1993年 | 9篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 11篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1975年 | 1篇 |
排序方式: 共有4314条查询结果,搜索用时 406 毫秒
131.
132.
Rosana S Lopes Marcelo M Cardoso Arthur O Sampaio Mario Santos BarbosaJr Celice C Souza Michelle C da Silva Elane Magno N Ferreira Marco Aurelio M Freire Rafael Rodrigues Lima Walace Gomes-Leal 《Journal of biosciences》2016,41(3):381-394
Neuroblasts from the subventricular zone (SVZ) migrate to striatum following stroke, but most of them die in the ischaemic milieu and this can be related to exacerbated microglial activation. Here, we explored the effects of the non-steroidal anti-inflammatory indomethacin on microglial activation, neuronal preservation and neuroblast migration following experimental striatal stroke in adult rats. Animals were submitted to endothelin-1 (ET-1)-induced focal striatal ischaemia and were treated with indomethacin or sterile saline (i.p.) for 7 days, being perfused after 8 or 14 days. Immunohistochemistry was performed to assess neuronal loss (anti-NeuN), microglial activation (anti-Iba1, ED1) and migrating neuroblasts (anti-DCX) by counting NeuN, ED1 and DCX-positive cells in the ischaemic striatum or SVZ. Indomethacin treatment reduced microglia activation and the number of ED1+ cells in both 8 and 14 days post injury as compared with controls. There was an increase in the number of DCX+ cells in both SVZ and striatum at the same survival times. Moreover, there was a decrease in the number of NeuN+ cells in indomethacin-treated animals as compared with the control group at 8 days but not after 14 days post injury. Our results suggest that indomethacin treatment modulates microglia activation, contributing to increased neuroblast proliferation in the SVZ and migration to the ischaemic striatum following stroke. 相似文献
133.
134.
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
135.
136.
Oxygen consumption and ammonia excretion of juvenile pink shrimp (Farfantepenaeus paulensis) in culture: temperature effects 总被引:1,自引:0,他引:1
Edison Barbieri Aline Maria Zigiotto de Medeiros Marcelo Barbosa Henriques 《Marine and Freshwater Behaviour and Physiology》2016,49(1):19-25
We evaluated oxygen consumption and ammonia excretion by juveniles of the pink shrimp Farfantepenaeus paulensis at three different temperatures (15, 20 and 25 °C). The shrimp were collected in the coastal region of Cananéia, São Paulo State, Brazil. The selected temperatures are the limits recorded in aquaculture tanks in the coastal region of Cananéia. We measured oxygen consumption and ammonia excretion as proxies for metabolic activity. Oxygen consumption and ammonia excretion increased with increasing temperature, but no change was observed at 15 and 20 °C. It is possible that within this temperature range, there is thermal independence in juvenile F. paulensis do not need to allocate additional energy to compensate for temperature changes because they are physiologically adapted for this range. 相似文献
137.
Disentangling the effects of drought,salinity, and sulfate on baldcypress growth in a coastal plain restored wetland 下载免费PDF全文
Because of their dominance in swamps of the southeastern United States, baldcypress (Taxodium distichum) trees are commonly used in wetland restoration. Though baldcypress are known to tolerate moderate flooding and salinity, their growth has been shown to decrease when they experience drought and high salinity. This study examined the effects of drought and elevated salinity on the growth of baldcypress seedlings and saplings. In a restored wetland in North Carolina, we examined the growth of 8‐year‐old baldcypress by measuring height and diameter at breast height (DBH) along salinity, nutrient, and flooding gradients. In a greenhouse, we placed 1‐year‐old baldcypress seedlings in either drought or saturated conditions and applied different water treatments: fresh water, sulfate, and artificial salt water (5 ppt [parts per thousand]). Over 26 weeks, we measured diameter at root collar, height, and biomass. In the field, chloride concentrations in soil solution had a negative effect on DBH and height (51 and 36% decrease, respectively); high water levels had a negative effect on height (47% decrease) and DBH (46% decrease). In the greenhouse, both drought and salinity decreased diameter growth (43 and 61% decline, respectively) and height (64 and 43% decline, respectively). Sulfate did not have a significant effect on diameter growth, but caused a 14% decrease in height. Our results suggest that both drought and salinity (even as low as 1 ppt) can lead to a 20–60% decline in baldcypress growth. Restoration practitioners should consider the negative consequences of both drought and increased salinity on baldcypress growth when planning for wetland restoration. 相似文献
138.
Soeth Marcelo Fávaro Luis Fernando Spach Henry Louis Daros Felippe Alexandre Woltrich Ana Emília Correia Alberto Teodorico 《Ichthyological Research》2019,66(1):140-154
Ichthyological Research - This is the first study to investigate the age, growth and reproductive biology of the Atlantic spadefish Chaetodipterus faber in southern Brazil. A total of 625... 相似文献
139.
Jessica Tauany Andrade Geisa Fantini de Figueiredo Luisa Ferreira Cruz Sarah Eliza de Morais Carla Daiane Ferreira Souza Flávia Carmo Horta Pinto Jaqueline Maria Siqueira Ferreira Marcelo Gonzaga de Freitas Araújo 《Revista iberoamericana de micología》2019,36(4):192-199
BackgroundCandida albicans is the main agent that causes vulvovaginal candidiasis. Resistance among isolates to azole antifungal agents has been reported.AimsDue to the well-known antifungal potential of curcumin, the purpose of this work was to evaluate the in vitro anticandidal activity of curcumin and its effect in the treatment of experimental vulvovaginal candidiasis.MethodsThe anticandidal activity of curcumin was investigated against eight Candida strains by the broth microdilution assay, and its mechanism of action was evaluated by testing the binding to ergosterol. Then, the effect of curcumin in the treatment of vulvovaginal candidiasis was evaluated in an immunosuppressed, estrogen treated rat model.ResultsCurcumin showed minimum inhibitory concentration values of 125–1000 μg/ml, and the best result was observed against Candida glabrata. The compound was shown to be able to bind to the ergosterol present in the membrane, event that may be the mechanism of action. In addition, in the in vivo model of vulvovaginal candidiasis with C. albicans, treatments reduced the vaginal fungal burden in infected rats after seven days of treatment with different doses.ConclusionsCurcumin could be considered a promising effective antifungal agent in the treatment of vulvovaginal candidiasis. 相似文献
140.
Llis A. Carlos‐Júnior Matthew Spencer Danilo Mesquita Neves Timothy Peter Moulton Dbora de Oliveira Pires Clovis Barreira e Castro Carlos Renato Rezende Ventura Carlos Eduardo Leite Ferreira Cristiana Silveira Serejo Simone Oigman‐Pszczol Fernanda Araújo Casares Marcelo Checoli Mantelatto Joel Christopher Creed 《Diversity & distributions》2019,25(5):743-757