全文获取类型
收费全文 | 125篇 |
免费 | 4篇 |
专业分类
129篇 |
出版年
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 14篇 |
2012年 | 12篇 |
2011年 | 9篇 |
2010年 | 9篇 |
2009年 | 4篇 |
2008年 | 8篇 |
2007年 | 12篇 |
2006年 | 6篇 |
2005年 | 5篇 |
2004年 | 6篇 |
2003年 | 3篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1977年 | 1篇 |
1895年 | 2篇 |
排序方式: 共有129条查询结果,搜索用时 15 毫秒
61.
Cera N Delli Pizzi S Di Pierro ED Gambi F Tartaro A Vicentini C Paradiso Galatioto G Romani GL Ferretti A 《PloS one》2012,7(6):e39118
Psychogenic erectile dysfunction (ED) has been defined as the persistent inability to attain and maintain an erection sufficient to permit sexual performance. It shows a high incidence and prevalence among men, with a significant impact on the quality of life. Few neuroimaging studies have investigated the cerebral basis of erectile dysfunctions observing the role played by prefrontal, cingulate, and parietal cortices during erotic stimulation. In spite of the well-known involvement of subcortical regions such as hypothalamus and caudate nucleus in male sexual response, and the key role of nucleus accumbens in pleasure and reward, poor attention was paid to their role in male sexual dysfunction. In this study, we determined the presence of grey matter (GM) atrophy patterns in subcortical structures such as amygdala, hippocampus, nucleus accumbens, caudate nucleus, putamen, pallidum, thalamus, and hypothalamus in patients with psychogenic ED and healthy men. After Rigiscan evaluation, urological, general medical, metabolic and hormonal, psychological and psychiatric assessment, 17 outpatients with psychogenic ED and 25 healthy controls were recruited for structural MRI session. Significant GM atrophy of nucleus accumbens was observed bilaterally in patients with respect to controls. Shape analysis showed that this atrophy was located in the left medial-anterior and posterior portion of accumbens. Left nucleus accumbens volumes in patients correlated with low erectile functioning as measured by IIEF-5 (International Index of Erectile Function). In addition, a GM atrophy of left hypothalamus was also observed. Our results suggest that atrophy of nucleus accumbens plays an important role in psychogenic erectile dysfunction. We believe that this change can influence the motivation-related component of sexual behavior. Our findings help to elucidate a neural basis of psychogenic erectile dysfunction. 相似文献
62.
N Margaritella L Mendozzi M Garegnani R Nemni E Colicino E Gilardi L Pugnetti 《BMC neurology》2012,12(1):80
ABSTRACT: BACKGROUND: The prognostic value of evoked potentials (EPs) in multiple sclerosis (MS) has not been fully established. The correlations between the Expanded Disability Status Scale (EDSS) at First Neurological Evaluation (FNE) and the duration of the disease, as well as between EDSS and EPs, have influenced the outcome of most previous studies. To overcome this confounding relations, we propose to test the prognostic value of EPs within an appropriate patient population which should be based on patients with low EDSS at FNE and short disease duration. METHODS: We retrospectively selected a sample of 143 early relapsing remitting MS (RRMS) patients with an EDSS < 3.5 from a larger database spanning 20 years. By means of bivariate logistic regressions, the best predictors of worsening were selected among several demographic and clinical variables. The best multivariate logistic model was statistically validated and prospectively applied to 50 patients examined during 2009--2011. RESULTS: The Evoked Potentials score (EP score) and the Time to EDSS 2.0 (TT2) were the best predictors of worsening in our sample (Odds Ratio 1.10 and 0.82 respectively, p=0.001). Low EP score (below 15--20 points), short TT2 (lower than 3--5 years) and their interaction resulted to be the most useful for the identification of worsening patterns. Moreover, in patients with an EP score at FNE below 6 points and a TT2 greater than 3 years the probability of worsening was 10% after 4--5 years and rapidly decreased thereafter. CONCLUSIONS: In an appropriate population of early RRMS patients, the EP score at FNE is a good predictor of disability at low values as well as in combination with a rapid buildup of disability. Interestingly, an EP score at FNE under the median together with a clinical stability lasting more than 3 years turned out to be a protective pattern. This finding may contribute to an early identification of benign patients, well before the term required to diagnose Benign MS (BMS). 相似文献
63.
ABSTRACT: BACKGROUND: Providing remote health monitoring to specific groups of patients represents an issue of great relevance for the national health systems, because of the costs related to moving health operators, the time spent to reach remote sites, and the high number of people needing health assistance. At the same time, some assistance activities, like those related to chronical diseases, may be satisfied through a remote interaction with the patient, without a direct medical examination. METHODS: Moving from this considerations, our paper proposes a system architecture for the provisioning of remote health assistance to older adults, based on a blind management of a network of wireless medical devices, and an interactive TV Set Top Box for accessing health related data. The selection of TV as the interface between the user and the system is specifically targeted to older adults. Due to the private nature of the information exchanged, a certified procedure is implemented for data delivery, through the use of non conditional smart cards. All these functions may be accomplished through a proper design of the system management, and a suitable interactive application. RESULTS: The interactive application acting as the interface between the user and the system on the TV monitor has been evaluated able to help readability and clear understanding of the contents and functions proposed. Thanks to the limited amount of data to transfer, even a Set Top Box equipped with a traditional PSTN modem may be used to support the proposed service at a basic level; more advanced features, like audio/video connection, may be activated if the Set Top Box enables a broadband connection (e.g. ADSL). CONCLUSIONS: The proposed layered architecture for a remote health monitoring system can be tailored to address a wide range of needs, according with each patient's conditions and capabilities. The system exploits the potentialities offered by Digital Television receivers, a friendly MHP interface, and the familiar remote control, to make the service effective and easy to use also for elderly people. 相似文献
64.
65.
66.
Trypanosoma brucei has three distinct ~20S editosomes that catalyze RNA editing by the insertion and deletion of uridylates. Editosomes with the KREN1 or KREN2 RNase III type endonucleases specifically cleave deletion and insertion editing site substrates, respectively. We report here that editosomes with KREPB2, which also has an RNase III motif, specifically cleave cytochrome oxidase II (COII) pre-mRNA insertion editing site substrates in vitro. Conditional repression and mutation studies also show that KREPB2 is an editing endonuclease specifically required for COII mRNA editing in vivo. Furthermore, KREPB2 expression is essential for the growth and survival of bloodstream forms. Thus, editing in T. brucei requires at least three compositionally and functionally distinct ~20S editosomes, two of which distinguish between different insertion editing sites. This unexpected finding reveals an additional level of complexity in the RNA editing process and suggests a mechanism for how the selection of sites for editing in vivo is controlled. 相似文献
67.
An in vivo model of hyperacute rejection: characterization and evaluation of the effect of transgenic human complement inhibitors 总被引:2,自引:0,他引:2
Mora M Lazzer M Marsicano G Mulder LC Carraresi L Pieri A Benanchi A Grifoni D Nuti S Bruzzone P Comporti M Cortesini R Rossini M 《Transgenic research》2000,9(3):205-213
Hyperacute rejection (HAR) occurring after transplantation within phylogenetically distant species is a severe reaction triggered by preexisting xenoreactive antibodies and complement activation, leading to the destruction of the donor organ. Expression of human complement inhibitors in transgenic pig organs prolongs the survival of xenograft in experimental models. Moreover, the extent of protection from hyperacute rejection is dependent on the level and site of expression of the transgenic molecules and, probably, on the combination of different molecules. In this regard a small animal model to test the efficacy of expression vectors and different human molecules could be very advantageous. A murine model developed in our laboratory was characterized by measurement of several parameters characteristic of HAR in the livers of control and transgenic mice expressing transgenic human DAF (CD55) or MCP (CD46) at the end of 2h of perfusion with human plasma and after 1 day. The parameters studied were heamatological values of hepatic functions (GOT and GPT), induction of pro-inflammatory molecules and histopathological evaluation. Cytokines (IL-1, IL-1, IL-6) induction and exposure of P-selectin on the endothelial cell surface, was only observed in control animals after 2h of perfusion, as an early event. GOT and GPT values increase drammatically after 2h perfusion and 1 day after the treatment according to the histopathological observation of liver damage. On the contrary, the livers of hDAF or hMCP transgenic mice, under the same treatment were significantly protected although the extent of this protection is dependent on the level of expression of transgenic human molecules. 相似文献
68.
Posidonia oceanica L. (Delile), an endemic species of the Mediterranean, forms extensive meadows which are continuously endangered by anthropic impacts. The availability of up-to-date information about interannual changes in shoot density of meadows and the knowledge of its expansion capabilities are crucial elements for the development of effective protection plans. Conversely, spatial ecology is becoming an increasingly important component of resource management, and the use of quantitative data for constructing prognosis maps of the dynamics of ecosystem degradation and restoration by nonlinear simulation methods is a topical field of landscape ecology. Unfortunately, little is known on spatial patterns of shoot density of P. oceanica on a small scale, despite their increasing use as indicators of the status and/or trends of meadows. The spatial structure of a continuous P. oceanica meadow, extending from 1 to 33 m depth in Lacco Ameno (Gulf of Naples, Italy), is investigated here by the “kriging” technique, a method widely used for geostatistical purposes. The analysis detected peculiar spatial patterns of shoot density and facilitated a small-scale (square meters) model of the distribution of P. oceanica. The highest shoot densities were found at the shallow stand (430 shoots m−2, on the average, with a peak of 1000 shoots m−2 in a relatively small area, at 1 m depth) and the lowest at the deep stand (average density <300 shoots m−2 below 15 m depth). A high degree of patchiness was found in the shallow stand, down to 10 m depth. Nestlike patterns with a rounded shape, characterized by shoot density radially decreasing from the center, were demonstrated mainly in the shallow stand. An opposite trend was detected in one case, where the main nestlike pattern was characterized by a decrease of density towards the center. Nestlike patterns may be generated by the confluence and overlap of stolons expanding from proximal areas. The comparison of density and depth models indicated that the shape of the seafloor influences the density structure of meadows and the growth patterns of P. oceanica. 相似文献
69.
Guido Polles Giuliana Indelicato Raffaello Potestio Paolo Cermelli Reidun Twarock Cristian Micheletti 《PLoS computational biology》2013,9(11)
Key steps in a viral life-cycle, such as self-assembly of a protective protein container or in some cases also subsequent maturation events, are governed by the interplay of physico-chemical mechanisms involving various spatial and temporal scales. These salient aspects of a viral life cycle are hence well described and rationalised from a mesoscopic perspective. Accordingly, various experimental and computational efforts have been directed towards identifying the fundamental building blocks that are instrumental for the mechanical response, or constitute the assembly units, of a few specific viral shells. Motivated by these earlier studies we introduce and apply a general and efficient computational scheme for identifying the stable domains of a given viral capsid. The method is based on elastic network models and quasi-rigid domain decomposition. It is first applied to a heterogeneous set of well-characterized viruses (CCMV, MS2, STNV, STMV) for which the known mechanical or assembly domains are correctly identified. The validated method is next applied to other viral particles such as L-A, Pariacoto and polyoma viruses, whose fundamental functional domains are still unknown or debated and for which we formulate verifiable predictions. The numerical code implementing the domain decomposition strategy is made freely available. 相似文献
70.
Roberto Danovaro Joan Batista Company Cinzia Corinaldesi Gianfranco D'Onghia Bella Galil Cristina Gambi Andrew J. Gooday Nikolaos Lampadariou Gian Marco Luna Caterina Morigi Karine Olu Paraskevi Polymenakou Eva Ramirez-Llodra Anna Sabbatini Francesc Sardà Myriam Sibuet Anastasios Tselepides 《PloS one》2010,5(8)
Deep-sea ecosystems represent the largest biome of the global biosphere, but
knowledge of their biodiversity is still scant. The Mediterranean basin has been
proposed as a hot spot of terrestrial and coastal marine biodiversity but has
been supposed to be impoverished of deep-sea species richness. We summarized all
available information on benthic biodiversity (Prokaryotes, Foraminifera,
Meiofauna, Macrofauna, and Megafauna) in different deep-sea ecosystems of the
Mediterranean Sea (200 to more than 4,000 m depth), including open slopes, deep
basins, canyons, cold seeps, seamounts, deep-water corals and deep-hypersaline
anoxic basins and analyzed overall longitudinal and bathymetric patterns. We
show that in contrast to what was expected from the sharp decrease in organic
carbon fluxes and reduced faunal abundance, the deep-sea biodiversity of both
the eastern and the western basins of the Mediterranean Sea is similarly high.
All of the biodiversity components, except Bacteria and Archaea, displayed a
decreasing pattern with increasing water depth, but to a different extent for
each component. Unlike patterns observed for faunal abundance, highest negative
values of the slopes of the biodiversity patterns were observed for Meiofauna,
followed by Macrofauna and Megafauna. Comparison of the biodiversity associated
with open slopes, deep basins, canyons, and deep-water corals showed that the
deep basins were the least diverse. Rarefaction curves allowed us to estimate
the expected number of species for each benthic component in different
bathymetric ranges. A large fraction of exclusive species was associated with
each specific habitat or ecosystem. Thus, each deep-sea ecosystem contributes
significantly to overall biodiversity. From theoretical extrapolations we
estimate that the overall deep-sea Mediterranean biodiversity (excluding
prokaryotes) reaches approximately 2805 species of which about 66% is
still undiscovered. Among the biotic components investigated (Prokaryotes
excluded), most of the unknown species are within the phylum Nematoda, followed
by Foraminifera, but an important fraction of macrofaunal and megafaunal species
also remains unknown. Data reported here provide new insights into the patterns
of biodiversity in the deep-sea Mediterranean and new clues for future
investigations aimed at identifying the factors controlling and threatening
deep-sea biodiversity. 相似文献