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排序方式: 共有769条查询结果,搜索用时 15 毫秒
221.
Eugenio Bortolini Luca Pagani Gregorio Oxilia Cosimo Posth Federica Fontana Federica Badino Tina Saupe Francesco Montinaro Davide Margaritora Matteo Romandini Federico Lugli Andrea Papini Marco Boggioni Nicola Perrini Antonio Oxilia Riccardo Aiese Cigliano Rosa Barcelona Davide Visentin Stefano Benazzi 《Current biology : CB》2021,31(11):2484-2493.e7
222.
Yuliya Krasylenko Jakub Těšitel Gregorio Ceccantini Mariana Oliveira-da-Silva Václav Dvořák Daniel Steele Yevhen Sosnovsky Renata Piwowarczyk David M. Watson Luiza Teixeira-Costa 《American journal of botany》2021,108(1):8-21
All organisms engage in parasitic relations, as either parasites or hosts. Some species may even play both roles simultaneously. Among flowering plants, the most widespread form of parasitism is characterized by the development of an intrusive organ called the haustorium, which absorbs water and nutrients from the host. Despite this functionally unifying feature of parasitic plants, haustoria are not homologous structures; they have evolved 12 times independently. These plants represent ca. 1% of all extant flowering species and show a wide diversity of life histories. A great variety of plants may also serve as hosts, including other parasitic plants. This phenomenon of parasitic exploitation of another parasite, broadly known as hyper- or epiparasitism, is well described among bacteria, fungi, and animals, but remains poorly understood among plants. Here, we review empirical evidence of plant hyperparasitism, including variations of self-parasitism, discuss the diversity and ecological importance of these interactions, and suggest possible evolutionary mechanisms. Hyperparasitism may provide benefits in terms of improved nutrition and enhanced host–parasite compatibility if partners are related. Different forms of self-parasitism may facilitate nutrient sharing among and within parasitic plant individuals, while also offering potential for the evolution of hyperparasitism. Cases of hyperparasitic interactions between parasitic plants may affect the ecology of individual species and modulate their ecosystem impacts. Parasitic plant phenology and disperser feeding behavior are considered to play a major role in the occurrence of hyperparasitism, especially among mistletoes. There is also potential for hyperparasites to act as biological control agents of invasive primary parasitic host species. 相似文献
223.
Perez-Cordon G Nie W Schmidt D Tzipori S Feng H 《Microbes and infection / Institut Pasteur》2011,13(1):103-107
Cryptosporidium parvum induces the formation of an actin-dense plaque which is essential for the successful invasion of epithelial cells. Host molecules that are involved in the regulation of this cytoskeleton reorganization are unknown. Here we identified that calcium-dependent thiol protease calpain is critical for regulating parasite-induced actin polymerization. C. parvum invasion induced activation of calpain. Inhibition of calpain activity by overexpression of the endogenous inhibitor calpastatin diminished the formation of the actin-dense plaque and decreased the initial invasion of parasites. Our data indicates a key role of calpain activity of host cell in C. parvum infection via regulating cytoskeleton reorganization. 相似文献
224.
Encarna Casas-Díaz Ignasi Marco Jorge R. López-Olvera Gregorio Mentaberre Santiago Lavín 《European Journal of Wildlife Research》2011,57(4):887-893
A comparison was made between two anaesthetic combinations in 35 free-ranging adult Iberian ibexes (Capra pyrenaica), from May to December 2005. Sixteen ibexes (10 males, 6 females) were captured using xylazine–ketamine (3.0 ± 0.4 + 3.0 ± 0.4 mg/kg)
and 19 ibexes (12 males, 7 females) with medetomidine–ketamine (0.10 ± 0.02 + 2.1 ± 0.3 mg/kg). Anaesthetic times were evaluated,
as well as clinical variables (respiratory and heart rates, rectal temperature, haemoglobin oxygen saturation), haematological
and biochemical variables, at the time of induction and after 1 h. The heart rate of ibex immobilized with medetomidine–ketamine
was higher than those immobilized with xylazine–ketamine. Stabilization of the heart rate of ibex immobilized with medetomidine–ketamine
came earlier than those immobilized with xylazine–ketamine. Rectal temperature decreased and stabilized in both groups, but
earlier in the xylazine–ketamine group, and hypoxemia was observed in both groups. The white blood cell count of ibex immobilized
with medetomidine–ketamine was lower than those immobilized with xylazine–ketamine throughout anaesthesia, while sodium concentration
was higher only after 1 h of anaesthesia. In ibex immobilized with xylazine–ketamine, the neutrophil count, serum creatinine
kinase activity and aspartate aminotransferase activity increased after 1 h of immobilization, while triglycerides decreased.
Changes found in haematological and biochemical variables suggest no major differences in the different drug combinations
used, but clinical findings of this study, as well as hypoxemia, hypothermia and bradycardia, were important records that
should be taken into account when performing a safe operation. 相似文献
225.
Persistence and abundance of species is determined by habitat availability and the ability to disperse and colonize habitats at contrasting spatial scales. Favourable habitat fragments are also heterogeneous in quality, providing differing opportunities for establishment and affecting the population dynamics of a species. Based on these principles, we suggest that the presence and abundance of epiphytes may reflect their dispersal ability, which is primarily determined by the spatial structure of host trees, but also by host quality. To our knowledge there has been no explicit test of the importance of host tree spatial pattern for epiphytes in Mediterranean forests. We hypothesized that performance and host occupancy in a favourable habitat depend on the spatial pattern of host trees, because this pattern affects the dispersal ability of each epiphyte and it also determines the availability of suitable sites for establishment. We tested this hypothesis using new point pattern analysis tools and generalized linear mixed models to investigate the spatial distribution and performance of the epiphytic lichen Lobaria pulmonaria, which inhabits two types of host trees (beeches and Iberian oaks). We tested the effects on L. pulmonaria distribution of tree size, spatial configuration, and host tree identity. We built a model including tree size, stand structure, and several neighbourhood predictors to understand the effect of host tree on L. pulmonaria. We also investigated the relative importance of spatial patterning on the presence and abundance of the species, independently of the host tree configuration. L. pulmonaria distribution was highly dependent on habitat quality for successful establishment, i.e., tree species identity, tree diameter, and several forest stand structure surrogates. For beech trees, tree diameter was the main factor influencing presence and cover of the lichen, although larger lichen-colonized trees were located close to focal trees, i.e., young trees. However, oak diameter was not an important factor, suggesting that bark roughness at all diameters favoured lichen establishment. Our results indicate that L. pulmonaria dispersal is not spatially restricted, but it is dependent on habitat quality. Furthermore, new spatial analysis tools suggested that L. pulmonaria cover exhibits a distinct pattern, although the spatial pattern of tree position and size was random. 相似文献
226.
Zhang H Zhang L Myerson J Bibee K Scott M Allen J Sicard G Lanza G Wickline S 《PloS one》2011,6(10):e26385
Rationale
Acute atherothrombotic occlusion in heart attack and stroke implies disruption of the vascular endothelial barrier that exposes a highly procoagulant intimal milieu. However, the evolution, severity, and pathophysiological consequences of vascular barrier damage in atherosclerotic plaque remain unknown, in part because quantifiable methods and experimental models are lacking for its in vivo assessment.Objective
To develop quantitative nondestructive methodologies and models for detecting vascular barrier disruption in advanced plaques.Methods and Results
Sustained hypercholesterolemia in New Zealand White (NZW) rabbits for >7–14 months engendered endothelial barrier disruption that was evident from massive and rapid passive penetration and intimal trapping of perfluorocarbon-core nanoparticles (PFC-NP: ∼250 nm diameter) after in vivo circulation for as little as 1 hour. Only older plaques (>7 mo), but not younger plaques (<3 mo) demonstrated the marked enhancement of endothelial permeability to these particles. Electron microscopy revealed a complex of subintimal spongiform channels associated with endothelial apoptosis, superficial erosions, and surface-penetrating cholesterol crystals. Fluorine (19F) magnetic resonance imaging and spectroscopy (MRI/MRS) enabled absolute quantification (in nanoMolar) of the passive permeation of PFC-NP into the disrupted vascular lesions by sensing the unique spectral signatures from the fluorine core of plaque-bound PFC-NP.Conclusions
The application of semipermeant nanoparticles reveals the presence of profound barrier disruption in later stage plaques and focuses attention on the disrupted endothelium as a potential contributor to plaque vulnerability. The response to sustained high cholesterol levels yields a progressive deterioration of the vascular barrier that can be quantified with fluorine MRI/MRS of passively permeable nanostructures. The possibility of plaque classification based on the metric of endothelial permeability to nanoparticles is suggested. 相似文献227.
Gregorio Moreno-Rueda 《法国昆虫学会纪事》2013,49(3):373-377
Arthropods frequently use empty snail shells as shelter or nesting sites. This study analyses the use of shells from the arid-dwelling land snail Sphincterochila candidissima (Draparnaud 1801) by arthropods in the Sierra Elvira (south-eastern Spain). Arthropods of 11 different orders occupied 15.6% of shells. Salticidae (54.6%) and Apoidea (21.3%) comprised the majority of arthropods. Shells were used primarily when environmental temperatures were lowest, suggesting that, in the Sierra Elvira, arthropods use shells to escape from the cold. Weather explained 73% of the variation in shell occupation. However, Apoidea used shells independently of weather, occupying shells as nesting chambers. These results suggest that snail shells may be important refugia and nesting sites for arthropod fauna. 相似文献
228.
Alejandro Yam-Puc Fabiola Escalante-Erosa Karlina García-Sosa Fabiola G. Ramírez-Torres Manuel J. Chan-Bacab Wolfgang Eisenreich Claudia Huber Nihat Knispel Gregorio Godoy-Hernández Luis M. Peña-Rodríguez 《Phytochemistry letters》2013,6(4):649-652
Lupeol-3-(3′R-hydroxy)-stearate, also known as procrim b (1), was isolated from the methanolic stem extract of Pentalinon andrieuxii and initially mistaken as lupeol acetate when analyzed by GC–MS only. The correct structure of 1 was established following a careful analysis of its NMR and MS data. 相似文献
229.
230.
Philipp Mahlknecht Stefan Kiechl Bastiaan R. Bloem Johann Willeit Christoph Scherfler Arno Gasperi Gregorio Rungger Werner Poewe Klaus Seppi 《PloS one》2013,8(7)