全文获取类型
收费全文 | 302篇 |
免费 | 25篇 |
出版年
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 8篇 |
2018年 | 6篇 |
2017年 | 4篇 |
2016年 | 24篇 |
2015年 | 21篇 |
2014年 | 23篇 |
2013年 | 23篇 |
2012年 | 19篇 |
2011年 | 24篇 |
2010年 | 13篇 |
2009年 | 11篇 |
2008年 | 11篇 |
2007年 | 11篇 |
2006年 | 10篇 |
2005年 | 10篇 |
2004年 | 16篇 |
2003年 | 11篇 |
2002年 | 8篇 |
2001年 | 5篇 |
2000年 | 8篇 |
1999年 | 3篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1995年 | 6篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有327条查询结果,搜索用时 15 毫秒
71.
72.
Franciélli Cristiane Gruchowski-Woitowicz Cláudia Inês da Silva Mauro Ramalho 《Ecological Entomology》2020,45(4):854-866
1. Generalists are assumed to play a key role in structuring and stabilising animal–plant mutualistic networks. Until now, analyses on the effects of generalists have been based on empirical field data or simulations. The present natural field experiment manipulated the abundance of a generalist and abundant stingless bee [Melipona (Eomelipona) marginata] to determine the effects on the mutualistic network. 2. Networks were generated, and associated metrics were used for comparing replicate plots with and without the insertion of stingless bee nests. 3. Unweighted metrics and the basic qualitative structural pattern of networks (high nestedness, very low modularity and specialisation) was not affected by experimental variation in stingless bee abundance because they exert strong basal effects on the plant–pollinator community under natural conditions of abundance. Still, increased abundance caused significant variation in weighted nestedness and modularity and community-level specialisation. 4. Supporting predictions of neutral models, increased abundance of the stingless bee led to an increase in most of its specific metrics, expressing the expansion of its realised trophic niche. 5. During this process, specialist and other generalist bees were affected in different ways. More plant species became even more dependent on this stingless bee (increased asymmetry). 6. Long-term effects could not be inferred directly from instantaneous values of network metrics. Nonetheless, the increased abundance of the generalist stingless bee may both reduce the local level of ecological specialisation in the short term and affect the spatial distribution of less abundant and/or specialist bee species and plants in the long term. 相似文献
73.
Pizetta Carolina Senhorinho Ramalho Ribeiro William Rafael Ferreira Amanda Lopes da Costa Moura Matheus Bonfim Kenny Pinheiro Patrícia Valle Cabral Glaucia Barbosa Aragão Francisco José Lima 《Plant Cell, Tissue and Organ Culture》2022,148(2):281-291
Plant Cell, Tissue and Organ Culture (PCTOC) - Whitefly (Bemisia tabaci) is a polyphagous insect that causes huge damage in several horticultural crops, including tomato, by sucking nutrients from... 相似文献
74.
Gabriela de Brito Sanchez João Ramalho Ortigão-Farias Monique Gauthier Fanglin Liu Martin Giurfa 《Arthropod-Plant Interactions》2007,1(2):69-76
The advent of the genomic era has opened new doors to understand the fundamental organization of living organisms and has
therefore promoted a fertile field of comparative research that intends to identify similarities and differences between related
and unrelated species at the genomic level. One of the organisms whose genome has been recently decoded is that of the honeybee
Apis mellifera, enabling a direct comparison with another well-studied insect, the fruit fly Drosophila melanogaster. It was reported that the honeybee has only ten gustatory receptors and thus a very poor taste perception compared to Drosophila, which presents 68 gustatory receptors, and the mosquito Anopheles gambiae, which presents 76 gustatory receptors. In this forum article, we discuss the implications of these findings taking into
account previous and new discoveries on honeybee gustation based on behavioral and neurobiological studies by several authors
and us. We conclude that the world of taste of a honeybee might not be as poor as proposed and that further studies should
integrate molecular, neurobiological, behavioral and ecological approaches to better characterize taste perception in bees.
Handling editor: Lars Chittka 相似文献
75.
Lopes VS Ramalho JS Owen DM Karl MO Strauss O Futter CE Seabra MC 《Traffic (Copenhagen, Denmark)》2007,8(5):486-499
The retinal pigment epithelium (RPE) contains melanosomes similar to those found in the skin melanocytes, which undergo dramatic light-dependent movements in fish and amphibians. In mammals, those movements are more subtle and appear to be regulated by the Rab27a GTPase and the unconventional myosin, Myosin VIIa (MyoVIIa). Here we address the hypothesis that a recently identified Rab27a- and MyoVIIa-interacting protein, Myrip, promotes the formation of a functional tripartite complex. In heterologous cultured cells, all three proteins co-immunoprecipitated following overexpression. Rab27a and Myrip localize to the peripheral membrane of RPE melanosomes as observed by immunofluorescence and immunoelectron microscopy. Melanosome dynamics were studied using live-cell imaging of mouse RPE primary cultures. Wild-type RPE melanosomes exhibited either stationary or slow movement interrupted by bursts of fast movement, with a peripheral directionality trend. Nocodazole treatment led to melanosome paralysis, suggesting that movement requires microtubule motors. Significant and similar alterations in melanosome dynamics were observed when any one of the three components of the complex was missing, as studied in ashen- (Rab27a defective) and shaker-1 (MyoVIIa mutant)-derived RPE cells, and in wild-type RPE cells transduced with adenovirus carrying specific sequences to knockdown Myrip expression. We observed a significant increase in the number of motile melanosomes, exhibiting more frequent and prolonged bursts of fast movement, and inversion of directionality. Similar alterations were observed upon cytochalasin D treatment, suggesting that the Rab27a-Myrip-MyoVIIa complex regulates tethering of melanosomes onto actin filaments, a process that ensures melanosome movement towards the cell periphery. 相似文献
76.
Comparison of resistance to drought of three bean cultivars 总被引:4,自引:0,他引:4
The aim of the present work was to evaluate oxidative stress and plant antioxidant system of three contrasting bean (Phaseolus vulgaris L.) genotypes in the response to drought. Drought was imposed 14 d after emergence, by withholding water, until leaf relative
water content reached 65 %. Water stress increased lipid peroxidation (LPO), membrane injury index, H2O2 and OH⋅ production in leaves of stressed plants. Activities of the antioxidative enzymes superoxide dismutase (SOD) and ascorbate
peroxidase (APOX) increased significantly under water stress in all the studied cultivars, while catalase (CAT) increased
in cvs. Plovdiv 10 and Prelom, but decreased in cv. Dobrudjanski ran. Furthermore cv. Plovdiv 10 which had the highest APOX
and CAT activities also showed the lowest increase in H2O2 and OH⋅ production and LPO while cv. Dobrudjanski ran showed the lowest increases (and often the lowest values) in the antioxidant
enzyme activities and the highest increases of H2O2 and OH⋅ production, and LPO. On the basis of the data obtained we could specify cv. Plovdiv 10 and cv. Prelom as drought tolerant
and cv. Dobrudjanski ran as a drought sensitive. 相似文献
77.
Tayyab A. Mansoor Rita M. Ramalho Silva Mulhovo Cecília M.P. Rodrigues Maria José U. Ferreira 《Bioorganic & medicinal chemistry letters》2009,19(15):4255-4258
Three known (1–3) and a novel (4) monoterpene indole alkaloids have been isolated from the methanol extract of leaves of Tabernaemontana elegans and their structures were elucidated by a series of spectroscopic experiments, involving NMR, MS, UV, and IR techniques. The isolated monoterpene indole alkaloids along with previously described β-carbolines (5–7) from the same specimen were studied for their apoptosis induction activity in human hepatoma HuH-7 cells. Methodology for apoptosis induction studies included cell viability assays, nuclear morphology assessments, and general caspase-3-like activity assays. The monoterpene indole alkaloids, tabernaemontanine (1) and vobasine (3) showed the most promising apoptosis induction profile in HuH-7 cells. 相似文献
78.
M. C. Matos P. S. Campos J. A. Passarinho J. N. Semedo N. M. Marques J. C. Ramalho C. P. Ricardo 《Photosynthetica》2010,48(2):303-312
Drought was induced in chickpea (Cicer arietinum L.) genotypes (ChK 3226 and ILC 3279) differing in yield capacity. Water stress (S1, RWC around 55–50%; S2, RWC ≤ 40%) drastically
reduced stomatal conductance (g
s) and net photosynthetic rate (P
N) in both genotypes. ILC 3279 showed greater photosynthetic capacity (A
max) decreases. Maximum PSII photochemical efficiency (Fv/Fm), photochemical quenching (qP), total chlorophylls (Chls) and carotenoids (Cars) content showed stability in both genotypes under stress, but in S2 ILC
3279 presented an increase in basal fluorescence (F0) and a greater reduction in estimation of quantum yield of linear electron transport (Φe) than ChK 3226. Membrane damage evaluated by electrolyte leakage occurred earlier and was greater in ILC 3279. It also presented
a decrease of total fatty acids (TFA) along drought, while in ChK 3226 greater amounts of TFA were observed in S1. In rehydration,
P
N of S1 plants completely recovered (ILC 3279) or remained slightly below control (ChK 3226). As regards S2 plants, ILC 3279
showed stronger P
N and g
s reductions than ChK 3226, despite both genotypes totally recovered A
max and chlorophyll (Chl) a fluorescence. ChK 3226 recovered more efficiently from membrane damage. Under control conditions, greater amounts of most
of the studied soluble metabolites occurred in ChK 3226 plants. Malate and citrate decreased with water stress (S2) in both
genotypes. Sucrose and pinitol (that had a higher concentration than sucrose in both genotypes) increased in ILC 3279 (S1
and S2), and decreased in ChK 3226 (S2). In ILC 3279 proline and asparagine followed similar patterns. Genotypes showed a
similar shoot dry mass (DM) in control plants, but root DM was higher in ChK 3226. Drought reduced root and shoot DM in ChK
3226 already under S1, while in ILC 3279 root DM was unaffected by drought and shoot biomass decreased only in S2. Root/shoot
ratio was always higher in ChK 3226 but tended to decrease under stress, while the opposite was observed in ILC 3279. No pods
were obtained from control plants of both genotypes, or droughted ILC 3279 plants. ChK 3226 produced pods under S1 (higher
yield) and S2. Under stress conditions, ChK 3226 was less affected in photosynthetic activity and membrane integrity, showing
a better tolerance to drought. This agrees with the better yield of this genotype under water stress. Distinct strategies
seem to underlie the different physiological responses of the two genotypes to water deficit. In spite of its significant
solutes accumulation, ILC 3279 was more affected in photosynthetic activity and membrane integrity during water stress than
ChK 3226, which showed better yield under drought. A relation could not be established between solutes accumulation of ILC
3279 and yield. 相似文献
79.
Background
Pathway-targeted or low-density arrays are used more and more frequently in biomedical research, particularly those arrays that are based on quantitative real-time PCR. Typical QPCR arrays contain 96-1024 primer pairs or probes, and they bring with it the promise of being able to reliably measure differences in target levels without the need to establish absolute standard curves for each and every target. To achieve reliable quantification all primer pairs or array probes must perform with the same efficiency. 相似文献80.
Araújo CP Gurgel CA Ramos EA Freitas VS Barbosa Ade A Ramalho LM dos Santos JN 《Journal of molecular histology》2010,41(6):357-365
LCs and MCs are known to be directly influenced by UV radiation. This study investigated the presence of Langerhans cells
(LCs) and mast cells (MCs) in actinic cheilitis (AC) exhibiting epithelial dysplasia (ED). Using immunohistochemistry for
CD1a and mast cell tryptase, LCs and MCs density was assessed in 35 cases of AC with different degrees of ED. LCs were found
in 32 cases of AC whereas MCs were found in all cases. There was an increase in LCs density irrespective of degree of ED when
the cases were compared to normal lip mucosa (P = 0.04343). No statistical difference in LCs density was observed regarding the different degrees of dysplasia (P > 0.05). Significant difference in MCs density between mild and moderate dysplasia and normal lip mucosa was found (P < 0.05). No significant correlation between LCs and MCs was seen (P = 0.1258). Although no correlation could be established between LCs and MCs and the different degrees of ED; it is possible
that the accumulation of LCs plays an immunostimulatory and protective role in the defense against progression of dysplasia.
Further studies are necessary to determine the role of MCs in the development of AC. 相似文献