全文获取类型
收费全文 | 139篇 |
免费 | 5篇 |
出版年
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 5篇 |
2017年 | 2篇 |
2016年 | 7篇 |
2015年 | 16篇 |
2014年 | 5篇 |
2013年 | 18篇 |
2012年 | 14篇 |
2011年 | 16篇 |
2010年 | 8篇 |
2009年 | 3篇 |
2008年 | 3篇 |
2007年 | 6篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 4篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1997年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1976年 | 1篇 |
1969年 | 2篇 |
排序方式: 共有144条查询结果,搜索用时 375 毫秒
81.
ARABIDILLO gene homologues in basal land plants: species-specific gene duplication and likely functional redundancy 总被引:1,自引:0,他引:1
Laura A. Moody Younousse Saidi Emma J. Smiles Susan J. Bradshaw Matthew Meddings Peter J. Winn Juliet C. Coates 《Planta》2012,236(6):1927-1941
ARABIDILLO proteins regulate multicellular root development in Arabidopsis thaliana. Conserved ARABIDILLO homologues are present throughout land plants, even in early-evolving plants that do not possess complex root architecture, suggesting that ARABIDILLO genes have additional functions. Here, we have cloned and characterised ARABIDILLO gene homologues from two early-evolving land plants, the bryophyte Physcomitrella patens and the lycophyte Selaginella moellendorffii. We show that two of the PHYSCODILLO genes (PHYSCODILLO1A and -1B) exist as a tail-to-tail tandem array of two almost identical 12?kb sequences, while a third related gene (PHYSCODILLO2) is located elsewhere in the Physcomitrella genome. Physcomitrella possesses a very low percentage of tandemly arrayed genes compared with the later-evolving plants whose genomes have been sequenced to date. Thus, PHYSCODILLO1A and -1B genes represent a relatively unusual gene arrangement. PHYSCODILLO promoters are active largely in the haploid gametophyte, with additional activity at the foot of the sporophyte. The pattern of promoter activity is uniform in filamentous and leafy tissues, suggesting pleiotropic gene functions and likely functional redundancy: the latter possibility is confirmed by the lack of discernible phenotype in a physcodillo2 deletion mutant. Interestingly, the pattern of PHYSCODILLO promoter activity in female reproductive organs is strikingly similar to that of an Arabidopsis homologue, suggesting co-option of some PHYSCODILLO functions or regulation into both the sporophyte and gametophyte. In conclusion, our work identifies and characterises some of the earliest-evolving land plant ARABIDILLO homologues. We confirm that all land plant ARABIDILLO genes arose from a single common ancestor and suggest that PHYSCODILLO proteins have novel and pleiotropic functions, some of which may be conserved in later-evolving plants. 相似文献
82.
Protein kinase C (PKC) isozymes are the paradigmatic effectors of lipid signaling. PKCs translocate to cell membranes and are allosterically activated upon binding of the lipid diacylglycerol to their C1A and C1B domains. The crystal structure of full-length protein kinase C βII was determined at 4.0 ?, revealing the conformation of an unexpected intermediate in the activation pathway. Here, the kinase active site is accessible to substrate, yet the conformation of the active site corresponds to a low-activity state because the ATP-binding side chain of Phe629 of the conserved NFD motif is displaced. The C1B domain clamps the NFD helix in a low-activity conformation, which is reversed upon membrane binding. A low-resolution solution structure of the closed conformation of PKCβII was derived from small-angle X-ray scattering. Together, these results show how PKCβII is allosterically regulated in two steps, with the second step defining a novel protein kinase regulatory mechanism. 相似文献
83.
Kawtar Bennani Imane Thami Alami Najib Bendaou Nezha Saidi Fatima Gaboun Chawki Al Faiz 《African Journal of Ecology》2011,49(1):1-9
The maintenance of species in an environment and the durability of rangeland and fallow improvement depend on the choice of populations used. The study of abundance and the relationship between the natural distribution of spontaneous legumes species of forage and/or pastoral interest and environmental factors is an important step for an adequate utilization of local genetic resources. Collection of annual Trifolium species and the genus of Lotus were conducted at 45 sites in Morocco in May/June 2004. Ecogeographical information was recorded at each site. Twelve species of annual Trifolium and two species of Lotus were identified. Most prolific were T. tomentosum and L. corniculatus. A principal components analysis and canonical variate analysis were conducted to group the sites, using the ecogeographical variables collected at each site. The variables that were found to be most important in grouping the sites were mean coldest month temperature, mean hottest month temperature, mean annual rainfall, latitude, longitude and soil pH. None of the species identified were limited to only one ecogeographical group. 相似文献
84.
Doyle AM Weiss HA Maganja K Kapiga S McCormack S Watson-Jones D Changalucha J Hayes RJ Ross DA 《PloS one》2011,6(9):e24866
Background
Despite recent decreases in HIV incidence in many sub-Saharan African countries, there is little evidence that specific behavioural interventions have led to a reduction in HIV among young people. Further and wider-scale decreases in HIV require better understanding of when behaviour change occurs and why. The MEMA kwa Vijana adolescent sexual and reproductive health intervention has been implemented in rural Mwanza, Tanzania since 1999. A long-term evaluation in 2007/8 found that the intervention improved knowledge, attitudes to sex and some reported risk behaviours, but not HIV or HSV2 prevalence. The aim of this paper was to assess the differential impact of the intervention according to gender, age, marital status, number of years of exposure and time since last exposure to the intervention.Methods
In 2007, a cross-sectional survey was conducted in the 20 trial communities among 13,814 young people (15–30 yrs) who had attended intervention or comparison schools between 1999 and 2002. Outcomes for which the intervention had an impact in 2001 or 2007 were included in this subgroup analysis. Data were analysed using cluster-level methods for stratified cluster-randomised trials, using interaction tests to determine if intervention impact differed by subgroup.Results
Taking into account multiplicity of testing, concurrence with a priori hypotheses and consistency within the results no strong effect-modifiers emerged. Impact on pregnancy knowledge and reported attitudes to sex increased with years of exposure to high-quality intervention.Conclusions
The desirable long-term impact of the MEMA kwa Vijana intervention did not vary greatly according to the subgroups examined. This suggests that the intervention can have an impact on a broad cross-section of young people in rural Mwanza.Trial registration
ClinicalTrials.gov NCT00248469相似文献85.
Saidi S Bouri F Lencel P Duplomb L Baud'huin M Delplace S Leterme D Miellot F Heymann D Hardouin P Palmer G Magne D 《Cytokine》2011,53(3):347-354
The aim of the present study was to investigate the potential role of the recently discovered IL-1 family member IL-33 in bone remodeling. Our results indicate that IL-33 mRNA is expressed in osteocytes in non-inflammatory human bone. Moreover, IL-33 levels are increased by TNF-α and IL-1β in human bone marrow stromal cells, osteoblasts and adipocytes obtained from three healthy donors. Experiments with the inhibitor GW-9662 suggested that expression of IL-33, in contrast to that of IL-1β, is not repressed by PPARγ likely explaining why IL-33, but not IL-1β, is expressed in adipocytes. The IL-33 receptor ST2L is not constitutively expressed in human bone marrow stromal cells, osteoblasts or CD14-positive monocytes, and IL-33 has no effect on these cells. In addition, although ST2L mRNA is induced by TNF-α and IL-1β in bone marrow stromal cells, IL-33 has the same effects as TNF-α and IL-1β, and, therefore, the biological activity of IL-33 may be redundant in this system. In agreement with this hypothesis, MC3T3-E1 osteoblast-like cells constitutively express ST2L mRNA, and IL-33 and TNF-α/IL-1β similarly decrease osteocalcin RNA levels in these cells. In conclusion, our results suggest that IL-33 has no direct effects on normal bone remodeling. 相似文献
86.
Suzanna C. Francis Kathy Baisley Shelley S. Lees Bahati Andrew Flavia Zalwango Janet Seeley Judith Vandepitte Trong T. Ao Janneke van de Wijgert Deborah Watson-Jones Saidi Kapiga Heiner Grosskurth Richard J. Hayes 《PloS one》2013,8(3)
Background
Intravaginal practices (IVP) are highly prevalent in sub-Saharan African and have been implicated as risk factors for HIV acquisition. However, types of IVP vary between populations, and detailed information on IVP among women at risk for HIV in different populations is needed. We investigated IVP among women who practice transactional sex in two populations: semi-urban, facility workers in Tanzania who engage in opportunistic sex work; and urban, self-identified sex workers and bar workers in Uganda. The aim of the study was to describe and compare IVP using a daily pictorial diary.Methodology/Principal Findings
Two hundred women were recruited from a HIV prevention intervention feasibility study in Kampala, Uganda and in North-West Tanzania. Women were given diaries to record IVP daily for six weeks. Baseline data showed that Ugandan participants had more lifetime partners and transactional sex than Tanzanian participants. Results from the diary showed that 96% of Tanzanian participants and 100% of Ugandan participants reported intravaginal cleansing during the six week study period. The most common types of cleansing were with water only or water and soap. In both countries, intravaginal insertion (e.g. with herbs) was less common than cleansing, but insertion was practiced by more participants in Uganda (46%) than in Tanzania (10%). In Uganda, participants also reported more frequent sex, and more insertion related to sex. In both populations, cleansing was more often reported on days with reported sex and during menstruation, and in Uganda, when participants experienced vaginal discomfort. Participants were more likely to cleanse after sex if they reported no condom use.Conclusions
While intravaginal cleansing was commonly practiced in both cohorts, there was higher frequency of cleansing and insertion in Uganda. Differences in IVP were likely to reflect differences in sexual behaviour between populations, and may warrant different approaches to interventions targeting IVP. Vaginal practices among women at high risk in Uganda and Tanzania: recorded behaviour from a daily pictorial diary. 相似文献87.
Francesca Lemme Aoife M. Doyle John Changalucha Aura Andreasen Kathy Baisley Kaballa Maganja Deborah Watson-Jones Saidi Kapiga Richard J. Hayes David A. Ross 《PloS one》2013,8(6)
Background
Young people are at high risk of HIV and developing appropriate prevention programmes requires an understanding of the risk factors for HIV in this age group. We investigated factors associated with HIV among participants aged 15–30 years in a 2007–8 cross-sectional survey nested within a community-randomised trial of the MEMA kwa Vijana intervention in 20 rural communities in northwest Tanzania.Methods
We analysed data for 7259(53%) males and 6476(47%) females. Using a proximate-determinant conceptual framework and conditional logistic regression, we obtained sex-specific Odds Ratios (ORs) for the association of HIV infection with socio-demographic, knowledge, behavioural and biological factors.Results
HSV-2 infection was strongly associated with HIV infection (females: adjOR 4.4, 95%CI 3.2–6.1; males: adjOR 4.2, 95%CI 2.8–6.2). Several socio-demographic factors (such as age, marital status and mobility), behavioural factors (condom use, number and type of sexual partnerships) and biological factors (blood transfusion, lifetime pregnancies, genital ulcers, Neisseria gonorrhoeae) were also associated with HIV infection. Among females, lifetime sexual partners (linear trend, p<0.001), ≥2 partners in the past year (adjOR 2.0, 95%CI 1.4–2.8), ≥2 new partners in the past year (adjOR 1.9 95%CI 1.2, 3.3) and concurrent partners in the past year (adjOR 1.6 95%CI 1.1, 2.4) were all associated with HIV infection.Conclusions
Efforts must be intensified to find effective interventions to reduce HSV-2. Effective behavioural interventions focusing on reducing the number of sexual partnerships and risk behaviour within partnerships are also needed. An increase in risky sexual behaviour may occur following marriage dissolution or when a young woman travels outside of her community and interventions addressing the needs of these subgroups of vulnerable women may be important.Trial Registration
ClinicalTrial.gov . NCT00248469相似文献88.
JinBin Tian Chhavy Tep Alex Benedick Nabila Saidi Jae Cheon Ryu Mi Lyang Kim Shankar Sadasivan John Oberdick Richard Smeyne Michael X. Zhu Sung Ok Yoon 《The Journal of biological chemistry》2014,289(45):31458-31472
p75 is expressed among Purkinje cells in the adult cerebellum, but its function has remained obscure. Here we report that p75 is involved in maintaining the frequency and regularity of spontaneous firing of Purkinje cells. The overall spontaneous firing activity of Purkinje cells was increased in p75−/− mice during the phasic firing period due to a longer firing period and accompanying reduction in silence period than in the wild type. We attribute these effects to a reduction in small conductance Ca2+-activated potassium (SK) channel activity in Purkinje cells from p75−/− mice compared with the wild type littermates. The mechanism by which p75 regulates SK channel activity appears to involve its ability to activate Rac1. In organotypic cultures of cerebellar slices, brain-derived neurotrophic factor increased RacGTP levels by activating p75 but not TrkB. These results correlate with a reduction in RacGTP levels in synaptosome fractions from the p75−/− cerebellum, but not in that from the cortex of the same animals, compared with wild type littermates. More importantly, we demonstrate that Rac1 modulates SK channel activity and firing patterns of Purkinje cells. Along with the finding that spine density was reduced in p75−/− cerebellum, these data suggest that p75 plays a role in maintaining normalcy of Purkinje cell firing in the cerebellum in part by activating Rac1 in synaptic compartments and modulating SK channels. 相似文献
89.
90.
Imen Hemissi Yassine Mabrouk Sonia Mejri Mouldi Saidi Bouaziz Sifi 《Journal of Phytopathology》2013,161(6):412-418
The aim of this work was to study the antagonist effect of two Rhizobium strains Pch Azm and Pch S.Nsir2 to Rhizoctonia solani and for an evaluation of the relative impact of rhizobia on the expression of the plant's defence response against Rhizoctonia. First, these strains reduced fungal growth observed in vitro using the same or separately Petri dishes. Moreover, these isolates led to reduced chickpea infection by R. solani, resulting from the direct effect of rhizobia on pathogens and possible induced resistance in chickpea. Concomitantly, reduction in infection was accompanied by enhanced level of defence‐related enzymes, phenylalanine ammonia lyase (PAL) and peroxidase (POX). An increased level of phenol content was recorded in the roots of bacterized plants grown in the presence of pathogen. The results promise the use of rhizobia for protection of chickpea against R. solani. 相似文献