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71.
Azevedo C São Clemente SC Casal G Matos P Alves  Al-Quraishy S Matos E 《Systematic parasitology》2012,82(3):241-247
Myxobolus myleus n. sp. is described from the gall-bladder of the freshwater fish Myleus rubripinnis collected near the city of Oriximiná in the Amazon System, Brazil. The spores obtained from the bile contained two equal symmetrical and smooth valves, each forming the spore wall. The spores were large, with a cone-like form, a semi spherical basal contour and measured (in μm) 19.3 ± 0.5 (n = 25) × 8.3 ± 0.5 (n = 25) × 4.0 ± 0.3 (n = 15). The apical end of the spores contained two elongate, equal and pointed conical polar capsules measuring 13.2 ± 0.4 μm (n = 25) in length and 3.0 ± 0.3 μm (n = 15) in width, each having a slightly tapering polar filament with 19 to 21 turns. The polar capsules were extended below at about 4/5 of the total length of the spores. The sporoplasm was binucleate and contained some sporoplasmosomes. All infected fish presented hypertrophy of the gall-bladder due to presence of the brownish parasite floating in the bile. In this paper we describe this new species of myxosporean based on light and ultrastructural observations, together with its associated pathology. 相似文献
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The range of a species is the result of the relative contribution of spatial tracking of environmental requirements and adaptation to ecological conditions outside the ancestral niche. The appearance of novel habitats caused by climatic oscillation can promote range expansion and accompanying demographic growth. The demographic dynamics of populations leave a signal in \ patterns. We modeled three competing scenarios pertaining to the circumstance of a range expansion by the Karoo Scrub‐Robin into newly available habitat resulting from the increasing aridification of southern Africa. Genetic variation was contrasted with the theoretical expectations of a spatial range expansion, and compared with data of a putative adaptive trait. We infer that this bird likely colonized the arid zone, as a consequence of adaptive evolution in a small peripheral population, followed by an expansion with recurrent exchange of migrants with the ancestral populations. 相似文献
75.
The Amazon harbours one of the richest ecosystems on Earth. Such diversity is likely to be promoted by plant specialization, associated with the occurrence of a mosaic of landscape units. Here, we integrate ecological and phylogenetic data at different spatial scales to assess the importance of habitat specialization in driving compositional and phylogenetic variation across the Amazonian forest. To do so, we evaluated patterns of floristic dissimilarity and phylogenetic turnover, habitat association and phylogenetic structure in three different landscape units occurring in terra firme (Hilly and Terrace) and flooded forests (Igapó). We established two 1-ha tree plots in each of these landscape units at the Caparú Biological Station, SW Colombia, and measured edaphic, topographic and light variables. At large spatial scales, terra firme forests exhibited higher levels of species diversity and phylodiversity than flooded forests. These two types of forests showed conspicuous differences in species and phylogenetic composition, suggesting that environmental sorting due to flood is important, and can go beyond the species level. At a local level, landscape units showed floristic divergence, driven both by geographical distance and by edaphic specialization. In terms of phylogenetic structure, Igapó forests showed phylogenetic clustering, whereas Hilly and Terrace forests showed phylogenetic evenness. Within plots, however, local communities did not show any particular trend. Overall, our findings suggest that flooded forests, characterized by stressful environments, impose limits to species occurrence, whereas terra firme forests, more environmentally heterogeneous, are likely to provide a wider range of ecological conditions and therefore to bear higher diversity. Thus, Amazonia should be considered as a mosaic of landscape units, where the strength of habitat association depends upon their environmental properties. 相似文献
76.
Pupal Period Affects Calling Behavior of the Wheat Moth, Pseudaletia sequax (Lepidoptera: Noctuidae)
Ângela A. Almeida Eraldo R. Lima & Ronaldo Reis Jr 《Ethology : formerly Zeitschrift fur Tierpsychologie》2008,114(5):499-503
The effects of pupal period and age on calling behavior of virgin females of Pseudaletia sequax were determined. Calling behavior of groups of females of similar age of pupation was observed every 10 min for six calling days. Females were considered calling when they assumed a characteristic position: wings and abdomen elevated, displaying the ovipositor and presumably releasing pheromone. Calling behavior was discontinuous. Females with a shorter pupal period took more time to start calling than females with a longer pupal period and called for a longer period. On the first day of calling, females took more time to initiate calling, on average during the seventh hour of the scotophase, whereas on the second day of calling, most females initiated calling during the fifth hour of the scotophase. On subsequent days of calling, the average time to initiate calling changed to the fourth hour of the scotophase. The mean time of calling per day decreased significantly with the number of days since first calling, and the mean number of calling bouts increased with days since first calling. 相似文献
77.
The antioxidant activity of β-carotene and oxygenated carotenoids lutein, canthaxanthin, and astaxanthin was investigated
during spontaneous and peroxyl-radical-induced cholesterol oxidation. Cholesterol oxidation, measured as generation of 7-keto-cholesterol
(7-KC), was evaluated in a heterogeneous solution with cholesterol, AAPH, and carotenoids solubilized in tetrahydrofuran and
in water, and in a homogeneous solution of chlorobenzene, with AIBN as a prooxidant. The formation of 7-KC was dependent on
temperature and on cholesterol and prooxidant concentrations. All the carotenoids tested, exhibited significant antioxidant
activity by inhibiting spontaneous, AAPH- and AIBN-induced formation of 7-KC, although the overall order of efficacy of these
compounds was astaxanthin > canthaxanthin > lutein = β-carotene. The finding that carotenoids exert protective effects on
spontaneous and free radical-induced cholesterol oxidation may have important beneficial effects on human health, by limiting
the formation of atheroma and by inhibiting cholesterol oxidation in food processing or storage. 相似文献
78.
79.
Three hundred and thirty nine lactic bacteria strains isolated from food samples were screened for antimicrobial activity.
Only one strain isolated from meat pie and identified as Enterococcus faecium produced a bacteriocin-like inhibitory substance (BLIS) showing activity against Enterococcus, Leuconostoc, Lactobacillus, Listeria, Corynebacterium and Staphylococcus aureus. The BLIS produced was resistant to acid and alkali treatment and 121oC for 15 min. The addition of BLIS in BHI contaminated
with Listeria monocytogenes decreased the contamination in 4.8 log cycles in 24 h. The inhibition of listeria was also obtained in milk. Forty multiresistant
enterococci strains were inhibited in the well-diffusion test. Two vancomycin resistant strains tested in liquid with BLIS
were also inhibited. The BLIS producer showed no pathogenicity marker. 相似文献
80.
Casado A Encarnación López-Fernández M Concepción Casado M de La Torre R 《Neurochemical research》2008,33(3):450-458
It has been reported that oxidative stress may play a role in the pathogenesis of dementia of the Alzheimer type (AD) and
the cerebral ischemia which causes vascular dementia (VD). We measured malondialdehyde (MDA) levels and superoxide dismutase
(SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) activities in blood samples from patients
with AD and VD and in healthy non-demented controls (CTR) which similar ages to the patients, in order to evaluate the degree
of oxidative stress in patients with AD and VD. A sample of 150 subjects consisting of 50 patients with AD; 50 patients with
VD and 50 CTR, aged from 65 to 85 years on, was analyzed. Most of the changes observed were in SOD activity and MDA levels. Catalase activity were least affected. Significant differences were observed in SOD and GR activity between males and females in CRT and in patients with AD, but
not in VD. We have found a decrease in antioxidant enzymes activities (SOD, CAT, GPx and GR) in patients with AD and VD and
significant differences were observed between CRT and AD patients for ages from 65 to 74, 75 to 84 and from 85 years to 94 years
in SOD activity and MDA levels (P < 0.001). MDA levels increase with age in VD, AD and CTR. No significant variation with respect to sex were detected, but
significant variations in MDA levels were detected between CRT and patients with VD and AD (P < 0.001). We conclude that oxidative stress plays an important role in the brain damage for both AD and VD, being observed
higher levels of oxidative stress for AD that for VD. 相似文献