全文获取类型
收费全文 | 474篇 |
免费 | 39篇 |
专业分类
513篇 |
出版年
2023年 | 16篇 |
2022年 | 22篇 |
2021年 | 41篇 |
2020年 | 21篇 |
2019年 | 19篇 |
2018年 | 16篇 |
2017年 | 23篇 |
2016年 | 32篇 |
2015年 | 28篇 |
2014年 | 22篇 |
2013年 | 34篇 |
2012年 | 57篇 |
2011年 | 29篇 |
2010年 | 10篇 |
2009年 | 13篇 |
2008年 | 9篇 |
2007年 | 11篇 |
2006年 | 10篇 |
2005年 | 6篇 |
2004年 | 6篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2001年 | 3篇 |
1998年 | 3篇 |
1991年 | 2篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1967年 | 2篇 |
1966年 | 4篇 |
1965年 | 3篇 |
1964年 | 2篇 |
1963年 | 2篇 |
1962年 | 3篇 |
1961年 | 1篇 |
排序方式: 共有513条查询结果,搜索用时 15 毫秒
501.
Alam M Miyoshi S Ahmed KU Hasan NA Tomochika K Shinoda S 《Microbiology and immunology》2006,50(11):845-850
Vibrio mimicus (Vm) haemagglutinins (HAs), such as an extracellular HA/protease (Vm-HA/protease) and a major outer membrane protein-HA (Vm-OMPHA), have been recognized as the putative adherence factors for the bacterium. However, the mechanism by which HAs coordinate the adherence function of the bacterium remains as yet unknown. We report herein the positive interaction between Vm-HA/protease and Vm-OMPHA resulting in significant enhancement of the haemagglutinating ability. In this interaction, no cleaved polypeptide was detected; however, limited proteolysis of Vm-OMPHA was confirmed by SDS-PAGE. The proteolytic activation of the native cell-associated Vm-OMPHA by limited proteolysis was also demonstrated in several V. mimicus strains. Proteolytic activation of OMPHA was also achieved with various proteases from bacterial and eukaryotic sources. These findings may indicate a novel coordination of V. mimicus HAs in the adherence of the bacterium. 相似文献
502.
Arakawa H Moldovan GL Saribasak H Saribasak NN Jentsch S Buerstedde JM 《PLoS biology》2006,4(11):e366
Proliferating cell nuclear antigen (PCNA) is a DNA polymerase cofactor and regulator of replication-linked functions. Upon DNA damage, yeast and vertebrate PCNA is modified at the conserved lysine K164 by ubiquitin, which mediates error-prone replication across lesions via translesion polymerases. We investigated the role of PCNA ubiquitination in variants of the DT40 B cell line that are mutant in K164 of PCNA or in Rad18, which is involved in PCNA ubiquitination. Remarkably, the PCNAK164R mutation not only renders cells sensitive to DNA-damaging agents, but also strongly reduces activation induced deaminase-dependent single-nucleotide substitutions in the immunoglobulin light-chain locus. This is the first evidence, to our knowledge, that vertebrates exploit the PCNA-ubiquitin pathway for immunoglobulin hypermutation, most likely through the recruitment of error-prone DNA polymerases. 相似文献
503.
NMDA receptor subunit composition controls dendritogenesis of hippocampal neurons through CAMKII,CREB‐P,and H3K27ac 下载免费PDF全文
Fernando J. Bustos Nur Jury Pablo Martinez Estibaliz Ampuero Matias Campos Sebastian Abarzúa Karen Jaramillo Susanne Ibing Muriel D. Mardones Henny Haensgen Julia Kzhyshkowska Maria Florencia Tevy Rachael Neve Magdalena Sanhueza Lorena Varela‐Nallar Martín Montecino Brigitte van Zundert 《Journal of cellular physiology》2017,232(12):3677-3692
504.
Background
Sylvian fissure (SF) is an important corridor in neurosurgery, and the end of sylvian fissure (eSF) represents the optimal target area to expose suitable recipient artery in STA-MCA bypass. Unfortunately little have been addressed concerning its relationship with external cranial surface.Objective
Correlation between Squamous Suture (SS) and SF was investigated.Methods
50-adult 3D-CTA images were studied using OSIRIX DICOM viewer. The measurement points were determined from external auditory meatus 0, 1, 1.5, 2, 2.5, 3, 3.5 and 4-cm anteriorly, perpendicular from orbitomeatal (OM) line. The distance of SF was compared with the one of SS.Results
SSs were all located below SF at 0 cm. At a distance of 0 to 1.5 cm, SSs were located above SF, then started to merge and went side by side from 2 cm anteriorly. Anterior sylvian point, the most anterior part of SF, was found at 4 cm from OM line. Inferior Rolandic point, which corresponds to the central sulcus inferior extent, was found to be at 2 cm from OM line. The eSF was identified at 0 cm anteriorly from OM, and perpendicularly 1.5 cm above SS. 50% patients had Chater''s point (CP) above eSF. Average value for CP was 0.01 below eSF, giving a significantly closer value compared to the one of SS (p<0.01). However, SS showed consistent value of 1.5 below SF. Furthermore, SS is a bony landmark, which has no shifting effect during surgery, therefore drawing a 1.5-cm line upward from SS could lead to exact location of eSF.Conclusion
The course of SF and its correlation to SS have been identified, and this is also the first study to investigate the relationship of SS and eSF using OSIRIX DICOM viewer. SS is also comparable to CP, therefore it is usable for a simple landmark of eSF. 相似文献505.
One hundred and twenty sites, from six localities from the Sudan Gezira were examined for soil mycoflora. The lower fungi were mostly represented by mucoraceous genera, such as Rhizopus, Mucor and Cunninghamella. Oomycetes were rare. Ascomycetes, other than the perfect states of Aspergillus, were not common. Only Chaetomium globosum was isolated from the six localities. Monascus, Thermoascus, Neocosmospora and Pyronema were recorded for the first time from Sudanese soils. The majority of the isolates were Hyphomycetes. The bulk of the fungal population were species of Aspergillus, of which A. niger was the most common, followed by A. terreus, A. flavus, A. nidulans and A. fumigatus. Other Aspergilli were sporadic. A. niveus and A. sejunctus were not previously reported from Sudanese soil. 相似文献
506.
本研究基于GEO数据库,选取由慢性乙型肝炎诱导的肝细胞癌芯片数据GSE121248为研究对象,利用GEO2R软件分析数据,筛选出差异表达基因,利用DAVID数据库进行GO分析和KEGG pathway富集分析.利用STRING数据库构建PPI网络,分析筛选核心基因.利用GEPIA对核心基因的表达进行验证,Kaplan ... 相似文献
507.
David G. Ainley Peter R. Wilson Kerry J. Barton Grant Ballard Nadav Nur Brian Karl 《Polar Biology》1998,20(5):311-319
We investigated the diet and aspects of foraging effort among Adélie penguins (Pygoscelis adeliae) breeding at three colonies on Ross Island, in the southwestern Ross Sea – Capes Royds, Bird and Crozier – during the chick-provisioning
period of three austral summers, 1994–1995, 1995–1996 and 1996–1997. During the study period, pack-ice cover differed in waters
offshore of these colonies, by colony, seasons and year. Diet differed among colonies only slightly. The fish Pleuragramma antarcticum was the most important prey, especially during years or periods within years when little pack ice was present. With respect
to krill, which composed the remainder of diet, juvenile Euphausia crystallorophias were consumed predominantly in a year of heavy pack-ice cover; more adult krill were consumed in 2 years when pack ice was
sparse. Foraging trip duration differed by colony, season and year and was related directly to distance from the colony to
the nearest pack ice. The amount of food brought to chicks increased as trip duration increased, to a point (2 days), but
then decreased as duration increased further (up to 4 days). On the basis of data on mass of parents and of meal sizes to
chicks, it appeared that on the longest trips more of the food gathered by parents was used for self maintenance; on the longest
trips, parents lost body mass. Successful foraging during chick rearing, the period when adult foraging is most intense, appears
to depend on the proximity of pack ice to nesting colonies for this penguin species.
Received: 1 October 1997 / Accepted: 25 April 1998 相似文献
508.
Uzi Nur 《Journal of morphology》1972,137(2):243-256
Males of the European elm scale, Gossyparia spuria (Erioccoccidae) have two Malphigian tubules, each made up of mononucleate and binucleate cells. Both types of cells may contain heterochromatic (H) chromosomes which form an H body. The cells with H bodies (H cells) usually appeared singly anywhere along the tubule. However, when two or more H cells were present they tended to be closer to each other than would be expected by chance. The possible origin of this tendency is discussed. Following squashing, the nuclei of the binucleate cells were much larger than those of most other somatic cells, suggesting that they were highly endopolyploid. However, the H bodies of the cells of the tubules were of about the same size as those of the other cells. These observations suggested that the H chromosomes of the binucleate cells did not replicate while the euchromatic chromosomes of these cells replicated several times. The great majority of the nuclei of the H cells contained a single H body per nucleus. An analysis of the number of H bodies in binucleate cells indicated that when two H bodies were present in the same nucleus they usually did not fuse. Thus, they were believed also not to fuse in the mononucleate cells. Since almost all the mononucleate H cells had only a single H body (rather than 2) it was concluded that they did not originate from binucleate cells by nuclear fusion. 相似文献
509.
Meat-eating was observed for the first time among a population of wild orang utans at Gunung Leuser National Park, Sumatra.
An adult female who was consorting with an adult male consumed a gibbon (Hylobates lar) carcass. There was no food sharing between the consort pair. The absence of food sharing is interpreted as indicative of
the anti-social attitude of adult orang utans. 相似文献
510.
Abdi Wira Septama Monika Arvia Chiara Gabriel Turnip Aprilia Nur Tasfiyati Rizna Triana Dewi Erlia Anggrainy Sianipar Amit Jaisi 《化学与生物多样性》2023,20(6):e202201205
Pseudomonas aeruginosa can regulate its pathogenicity via quorum sensing (QS) system. Zingiber cassumunar and Z. officinale have been used for the treatment of infectious diseases. The study aimed to evaluate and compare the chemical constituents, antibacterial, and QS inhibitor of Z. cassumunar essential oils (ZCEO) and Z. officinale essential oils (ZOEO). The chemical constituent was analysed using GC/MS. Broth microdilution and spectrophotometry analysis were used to evaluate their antibacterial and QS inhibitor activities. The main constituent of ZOEO with percent composition above 6 % (α-curcumene, α-zingiberene, β-sesquiphellandrene, and β-bisabolene, α-citral, and α-farnesene) were exist in a very minimal percentage less than 0.7 % in Z. cassumunar. All major components of ZCEO with percentages higher than 5 % (terpinen-4-ol, sabinene, γ-terpinene) were present in low proportion (<1.18 %) in Z. officinale. ZCEO demonstrated moderate antibacterial activity against P. aeruginosa. The combination of ZCEO and tetracycline showed a synergistic effect (FICI of 0.5). ZCEO exhibited strong activity in inhibiting biofilm formation. ZCEO at MIC (62.5 μg/mL) was able to reduce pyoverdine, pyocyanin, and proteolytic activity. This is the first report on the activity of ZCEO in the inhibition of P. aeruginosa QS system and it may be used to control the pathogenicity of P. aeruginosa. 相似文献