全文获取类型
收费全文 | 329篇 |
免费 | 18篇 |
专业分类
347篇 |
出版年
2023年 | 6篇 |
2022年 | 3篇 |
2021年 | 13篇 |
2020年 | 5篇 |
2019年 | 11篇 |
2018年 | 7篇 |
2017年 | 9篇 |
2016年 | 11篇 |
2015年 | 20篇 |
2014年 | 13篇 |
2013年 | 26篇 |
2012年 | 26篇 |
2011年 | 24篇 |
2010年 | 15篇 |
2009年 | 12篇 |
2008年 | 20篇 |
2007年 | 25篇 |
2006年 | 13篇 |
2005年 | 15篇 |
2004年 | 13篇 |
2003年 | 5篇 |
2002年 | 14篇 |
2001年 | 3篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1979年 | 5篇 |
1978年 | 1篇 |
1976年 | 3篇 |
1970年 | 1篇 |
1935年 | 1篇 |
1934年 | 2篇 |
1930年 | 1篇 |
排序方式: 共有347条查询结果,搜索用时 15 毫秒
151.
Muratbegović AA Marković N Zukanović A Kobaslija S Dragas MS Jurić H 《Collegium antropologicum》2010,34(3):1027-1033
The main aim of this paper is to present epidemiological indicators of oral health among six-year olds in Bosnia and Herzegovina (BH) and to analyze values of dmft index and dental treatment needs in order to identify differences in parts of the country. Another aim is to identify the needs from the public oral health care system in Bosnia and Herzegovina related to early permanent dentition by analyzing the condition of first permanent molars (FPM) as an indicator of oral health of permanent dentition. Survey was carried out in 2004 in 8 cantons of the Federation of BH (FBH) and in the Republic of Srpska (RS). Final sample included 560 participants aged six (mean 6.2, SD +/- 0.87). One dental team clinically examined all participants according to WHO methodology and criteria. The parameters used were: dmft index, DMFT index of first permanent molars (FPM), presence of sealants and treatment needs. A questionnaire about oral health habits had been administered. Dmft was 6.71 in that the d-component constituted the major part of the index. DMFT index of FPM was 0.61 (SD +/- 1.08). Percentage of caries free participants aged 6 was 6.8%. Average number of FPM with fissure sealants in BH was 0.25 (SD +/- 0.78). Significant demographic differences in dmft index, DMFT FPM and treatment needs were identified. Most participants (48.5%) had their first dental visit between the ages of five and seven. National oral health goal for Bosnia and Herzegovina should be to develop and implement disease prevention programs based on education of both parents and dental practitioners. It is necessary to improve access to dental care and shift focus from curative to preventive procedures. It is also necessary to set real goals for improvement of oral health which can be achieved within a desired time frame, as well as to precisely define measures to be taken. 相似文献
152.
Mi Jin Moon Hee Young Kim Sin Gon Kim Juri Park Dong Seop Choi Jong-Ik Hwang Jae Young Seong 《Molecules and cells》2010,30(2):149-154
Glucagon like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are incretin hormones released in response
to food intake and potentiate insulin secretion from pancreatic β cells through their distinct yet related G protein-coupled
receptors, GLP1R and GIPR. While GLP-1 and GIP exhibit similarity in their N-terminal sequence and overall α-helical structure,
GLP-1 does not bind to GIPR and vice versa. To determine which amino acid residues of these peptide ligands are responsible
for specific interaction with their respective receptors, we generated mutant GIP in which several GLP-1-specific amino acid
residues were substituted for the original amino acids. The potency of the mutant ligands was examined using HEK293 cells
transfected with GLP1R or GIPR expression plasmids together with a cAMP-responsive element-driven luciferase (CRE-luc) reporter
plasmid. A mutated GIP peptide in which Tyr1, Ile7, Asp15, and His18 were replaced by His, Thr, Glu, and Ala, respectively, was able to activate both GLP1R and GIPR with moderate potency. Replacing
the original Tyr1 and/or Ile7 in the N-terminal moiety of this mutant peptide allowed full activation of GIPR but not of GLP1R. However, reintroducing
Asp15 and/or His18 in the central α-helical region did not significantly alter the ligand potency. These results suggest that Tyr/His1 and Ile/Thr7 of GIP/GLP-1 peptides confer differential ligand selectivity toward GIPR and GLP1R. 相似文献
153.
Ayub MJ Nyambega B Simonetti L Duffy T Longhi SA Gómez KA Hoebeke J Levin MJ Smulski CR 《PloS one》2012,7(5):e36233
The ribosomal P proteins are located on the stalk of the ribosomal large subunit and play a critical role during the elongation step of protein synthesis. The single chain recombinant antibody C5 (scFv C5) directed against the C-terminal region of the Trypanosoma cruzi P2β protein (TcP2β) recognizes the conserved C-terminal end of all T. cruzi ribosomal P proteins. Although this region is highly conserved among different species, surface plasmon resonance analysis showed that the scFv C5 possesses very low affinity for the corresponding mammalian epitope, despite having only one single amino-acid change. Crystallographic analysis, in silico modelization and NMR assays support the analysis, increasing our understanding on the structural basis of epitope specificity. In vitro protein synthesis experiments showed that scFv C5 was able to specifically block translation by T. cruzi and Crithidia fasciculata ribosomes, but virtually had no effect on Rattus norvegicus ribosomes. Therefore, we used the scFv C5 coding sequence to make inducible intrabodies in Trypanosoma brucei. Transgenic parasites showed a strong decrease in their growth rate after induction. These results strengthen the importance of the P protein C terminal regions for ribosomal translation activity and suggest that trypanosomatid ribosomal P proteins could be a possible target for selective therapeutic agents that could be derived from structural analysis of the scFv C5 antibody paratope. 相似文献
154.
Cittaro D Borsotti D Maiolica A Argenzio E Rappsilber J 《Journal of proteome research》2005,4(3):1006-1011
Traditionally, peptide identification using fragmentation spectra relies on extracting the maximum amount of information from spectra. Using different combinations of small ion masses, we show that identifying a small number of fragment ions in a spectrum is sufficient for peptide identification. We consider y2-, y3-, b2-, and b3-ions and find the combination of b2-y2 to be sufficient for many peptides. Adding either the y3- or the b3-ion increases specificity and allows reliable peptide identification in the human proteome. Fragmentation spectra and peptides are represented as n-dimensional vectors, where n is given by the number of fragment ions considered, and the peptide mass. The identification score is given by the Euclidian distance between the spectra and the matching peptide in n-dimensional space. We show that this approach, using minimal information, allows for precise and fast peptide identification. 相似文献
155.
Ildikó Király Juri Nascimbene Flóra Tinya Péter Ódor 《Biodiversity and Conservation》2013,22(1):209-223
The effect of management related factors on species richness of epiphytic bryophytes and lichens was studied in managed deciduous-coniferous mixed forests in Western-Hungary. At the stand level, the potential explanatory variables were tree species composition, stand structure, microclimate and light conditions, landscape and historical variables; while at tree level host tree species, tree size and light were studied. Species richness of the two epiphyte groups was positively correlated. Both for lichen and bryophyte plot level richness, the composition and diversity of tree species and the abundance of shrub layer were the most influential positive factors. Besides, for bryophytes the presence of large trees, while for lichens amount and heterogeneity of light were important. Tree level richness was mainly determined by host tree species for both groups. For bryophytes oaks, while for lichens oaks and hornbeam turned out the most favourable hosts. Tree size generally increased tree level species richness, except on pine for bryophytes and on hornbeam for lichens. The key variables for epiphytic diversity of the region were directly influenced by recent forest management; historical and landscape variables were not influential. Forest management oriented to the conservation of epiphytes should focus on: (i) the maintenance of tree species diversity in mixed stands; (ii) increment the proportion of deciduous trees (mainly oaks); (iii) conserving large trees within the stands; (iv) providing the presence of shrub and regeneration layer; (v) creating heterogeneous light conditions. For these purposes tree selection and selective cutting management seem more appropriate than shelterwood system. 相似文献
156.
Vesa-Petteri Kouri Juri Olkkonen Emilia Kaivosoja Mari Ainola Juuso Juhila Iiris Hovatta Yrj? T. Konttinen Jami Mandelin 《PloS one》2013,8(1)
Introduction
Patients with rheumatoid arthritis (RA) have disturbances in the hypothalamic-pituitary-adrenal (HPA) axis. These are reflected in altered circadian rhythm of circulating serum cortisol, melatonin and IL-6 levels and in chronic fatigue. We hypothesized that the molecular machinery responsible for the circadian timekeeping is perturbed in RA. The aim of this study was to investigate the expression of circadian clock in RA.Methods
Gene expression of thirteen clock genes was analyzed in the synovial membrane of RA and control osteoarthritis (OA) patients. BMAL1 protein was detected using immunohistochemistry. Cell autonomous clock oscillation was started in RA and OA synovial fibroblasts using serum shock. The effect of pro-inflammatory stimulus on clock gene expression in synovial fibroblasts was studied using IL-6 and TNF-α.Results
Gene expression analysis disclosed disconcerted circadian timekeeping and immunohistochemistry revealed strong cytoplasmic localization of BMAL1 in RA patients. Perturbed circadian timekeeping is at least in part inflammation independent and cell autonomous, because RA synovial fibroblasts display altered circadian expression of several clock components, and perturbed circadian production of IL-6 and IL-1β after clock resetting. However, inflammatory stimulus disturbs the rhythm in cultured fibroblasts. Throughout the experiments ARNTL2 and NPAS2 appeared to be the most affected clock genes in human immune-inflammatory conditions.Conclusion
We conclude that the molecular machinery controlling the circadian rhythm is disturbed in RA patients. 相似文献157.
Vineyards are amongst the most intensive forms of agriculture often resulting in simplified landscapes where semi-natural vegetation is restricted to small scattered patches. However, a tendency toward a more sustainable management is stimulating research on biodiversity in these poorly investigated agro-ecosystems. The main aim of this study was to test the effect on plant diversity of management intensity and topography in vineyards located in a homogenous intensive hilly landscape. Specifically, this study evaluated the role of slope, mowing and herbicide treatments frequency, and nitrogen supply in shaping plant diversity and composition of life-history traits. The study was carried out in 25 vineyards located in the area of the Conegliano-Valdobbiadene DOCG (Veneto, NE Italy). In each vineyard, 10 plots were placed and the abundance of all vascular plants was recorded in each plot. Linear multiple regression was used to test the effect of management and topography on plant diversity. Management intensity and topography were both relevant drivers of plant species diversity patterns in our vineyards. The two most important factors were slope and mowing frequency that respectively yielded positive and negative effects on plant diversity. A significant interaction between these two factors was also demonstrated, warning against the detrimental effects of increasing mowing intensity on steep slope where plant communities are more diverse. The response of plant communities to mowing frequency is mediated by a process of selection of resistant growth forms, such in the case of rosulate and reptant species. The other two management-related factors tested in this study, number of herbicide treatments and N fertilization, were less influential. In general, our study corroborates the idea that some simple changes in farming activities, which are compatible with grape production, should be encouraged for improving the natural and cultural value of the landscape by maintaining and improving wild plant diversity. 相似文献
158.
Juri Kim Hye Yeon Lee Mi-Ae Lee Tai-Soon Yong Kyu-Ho Lee Soon-Jung Park 《Experimental parasitology》2013
Giardia lamblia is a protozoan pathogen with distinct cytoskeletal structures, including median bodies and eight flagella. In this study, we examined components comprising G. lamblia flagella. Crude flagellar extracts were prepared from G. lamblia trophozoites, and analyzed by two-dimensional (2-D) gel electrophoresis. The 19 protein spots were analyzed by MALDI–TOF mass spectrometry, identifying ten metabolic enzymes, six distinct giardins, Giardia trophozoite antigen 1, translational initiation factor eIF-4A, and an extracellular signal-regulated kinase 2. Among the identified proteins, we studied α-11 giardin which belongs to a group of cytoskeletal proteins specific to Giardia. Western blot analysis and real-time PCR indicated that expression of α-11 giardin is not significantly increased during encystation of G. lamblia. Immunofluorescence assays using anti-α-11 giardin antibodies revealed that α-11 giardin protein mainly localized to the plasma membranes and basal bodies of the anterior flagella of G. lamblia trophozoites, suggesting that α-11 giardin is a genuine component of the G. lamblia cytoskeleton. 相似文献
159.
Yusuke Kondo Masahiro To Juri Saruta Takashi Hayashi Hiroki Sugiyama Keiichi Tsukinoki 《Journal of neurochemistry》2013,124(2):224-232
Expression of tyrosine receptor kinase B (TrkB), a receptor for brain‐derived neurotrophic factor (BDNF), is markedly elevated in the adrenal medulla during immobilization stress. Catecholamine release was confirmed in vitro by stimulating chromaffin cells with recombinant BDNF. We investigated the role of TrkB and the localization of BDNF in the adrenal gland during immobilization stress for 60 min. Blood catecholamine levels increased after stimulation with TrkB expressed in the adrenal medulla during 60‐min stress; however, blood catecholamine levels did not increase in adrenalectomized rats. Furthermore, expression of BDNF mRNA and protein was detected in the adrenal medulla during 60‐min stress. Similarly, in rats undergoing sympathetic nerve block with propranolol, BDNF mRNA and protein were detected in the adrenal medulla during 60‐min stress. These results suggest that signal transduction of TrkB in the adrenal medulla evokes catecholamine release. In addition, catecholamine release was evoked by both the hypothalamic–pituitary–adrenal axis and autocrine signaling by BDNF in the adrenal gland. BDNF–TrkB interaction may play a role in a positive feedback loop in the adrenal medulla during immobilization stress. 相似文献
160.
Legumes carry out special biochemical functions, e.g. the fixation of molecular nitrogen based on a symbiosis with proteobacteria. At the cellular level, this symbiosis has to be implemented into the energy metabolism of the host cell. To provide a basis for future analyses, we have characterized the protein complement of mitochondria of the model legume Medicago truncatula using two-dimensional isoelectric focussing (IEF) and blue-native (BN)-SDS-PAGE. While the IEF reference map resulted mainly in resolution of those proteins associated with the mitochondrial matrix, the BN proteomic map allowed separation of protein subunits from the respiratory chain protein complexes, which are located in the organelle's inner membrane. The M. truncatula mitochondrial BN reference map revealed some striking similarities to the one from Arabidopsis thaliana but at the same time exhibited also some special features: complex II is of increased abundance and additionally represented by a low molecular mass form not reported for Arabidopsis. Furthermore three highly abundant forms of prohibitin complexes are present in the mitochondrial proteome of M. truncatula. Special features with respect to mitochondrial protein complexes might reflect adaptations of legumes to elevated cellular energy requirements enabling them to develop symbiotic interactions with rhizobial bacteria. 相似文献