全文获取类型
收费全文 | 374篇 |
免费 | 30篇 |
国内免费 | 10篇 |
出版年
2022年 | 2篇 |
2021年 | 1篇 |
2019年 | 1篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 13篇 |
2014年 | 11篇 |
2013年 | 8篇 |
2012年 | 14篇 |
2011年 | 11篇 |
2010年 | 13篇 |
2009年 | 17篇 |
2008年 | 13篇 |
2007年 | 13篇 |
2006年 | 12篇 |
2005年 | 18篇 |
2004年 | 20篇 |
2003年 | 17篇 |
2002年 | 14篇 |
2001年 | 22篇 |
2000年 | 19篇 |
1999年 | 11篇 |
1998年 | 11篇 |
1997年 | 9篇 |
1996年 | 5篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 16篇 |
1992年 | 27篇 |
1991年 | 9篇 |
1990年 | 4篇 |
1989年 | 8篇 |
1988年 | 10篇 |
1987年 | 8篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1974年 | 3篇 |
1972年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有414条查询结果,搜索用时 15 毫秒
51.
Riley MR DeRosa D Blaine J Potter BG Lucas P Le Coq D Juncker C Boesewetter DE Collier JM Boussard-Plédel C Bureau B 《Biotechnology progress》2006,22(1):24-31
This work describes the development of a biologically based sensing technique to quantify chemical agents that pose inhalation health hazards. The approach utilizes cultured epithelial cells (A549 human type II pneumocytes) of the lung, exposed to potential toxins and monitored through the noninvasive means of infrared spectroscopy to quantify changes to cell physiology and function. Cell response to Streptolysin O, a cholesterol-binding cytolysin, is investigated here. Infrared spectra display changes in cell physiology indicative of membrane damage, altered proteins, and some nucleic acid damage. Methods to improve cell adhesion through modification of support surface properties are detailed. This spectroscopic approach not only provides a robust means to detect potential toxins but also provides information on modes of damage and mechanisms of cellular response. 相似文献
52.
RP Tucker K Drabikowski JF Hess J Ferralli R Chiquet-Ehrismann JC Adams 《BMC evolutionary biology》2006,6(1):60-17
Background
Tenascins are a family of glycoproteins found primarily in the extracellular matrix of embryos where they help to regulate cell proliferation, adhesion and migration. In order to learn more about their origins and relationships to each other, as well as to clarify the nomenclature used to describe them, the tenascin genes of the urochordate Ciona intestinalis, the pufferfish Tetraodon nigroviridis and Takifugu rubripes and the frog Xenopus tropicalis were identified and their gene organization and predicted protein products compared with the previously characterized tenascins of amniotes. 相似文献53.
Background
Trichomonosis caused by Trichomonas vaginalis is the number one, non-viral sexually transmitted disease (STD) that affects more than 250 million people worldwide. Immunoglobulin A (IgA) has been implicated in resistance to mucosal infections by pathogens. No reports are available of IgA-reactive proteins and the role, if any, of this class of antibody in the control of this STD. The availability of an IgA monoclonal antibody (mAb) immunoreactive to trichomonads by whole cell (WC)-ELISA prompted us to characterize the IgA-reactive protein of T. vaginalis. 相似文献54.
Darsonval A Darrasse A Meyer D Demarty M Durand K Bureau C Manceau C Jacques MA 《Applied and environmental microbiology》2008,74(9):2669-2678
Understanding the survival, multiplication, and transmission to seeds of plant pathogenic bacteria is central to study their pathogenesis. We hypothesized that the type III secretion system (T3SS), encoded by hrp genes, could have a role in host colonization by plant pathogenic bacteria. The seed-borne pathogen Xanthomonas fuscans subsp. fuscans causes common bacterial blight of bean (Phaseolus vulgaris). Directed mutagenesis in strain CFBP4834-R of X. fuscans subsp. fuscans and bacterial population density monitoring on bean leaves showed that strains with mutations in the hrp regulatory genes, hrpG and hrpX, were impaired in their phyllospheric growth, as in the null interaction with Escherichia coli C600 and bean. In the compatible interaction, CFBP4834-R reached high phyllospheric population densities and was transmitted to seeds at high frequencies with high densities. Strains with mutations in structural hrp genes maintained the same constant epiphytic population densities (1 x 10(5) CFU g(-1) of fresh weight) as in the incompatible interaction with Xanthomonas campestris pv. campestris ATCC 33913 and the bean. Low frequencies of transmission to seeds and low bacterial concentrations were recorded for CFBP4834-R hrp mutants and for ATCC 33913, whereas E. coli C600 was not transmitted. Moreover, unlike the wild-type strain, strains with mutations in hrp genes were not transmitted to seeds by vascular pathway. Transmission to seeds by floral structures remained possible for both. This study revealed the involvement of the X. fuscans subsp. fuscans T3SS in phyllospheric multiplication and systemic colonization of bean, leading to transmission to seeds. Our findings suggest a major contribution of hrp regulatory genes in host colonization processes. 相似文献
55.
56.
黑龙江省森林景观多样性动态 总被引:10,自引:0,他引:10
讨论了1949—1981年黑龙江省森林景观多样性的动态。利用1949年和1981年森林资源分布图,选取7个有代表性的度量景观多样性的定量指标:斑块密度、周长-面积分数维、聚集度、斑块散布与毗连指数、Shannon多样性指数、优势度、均匀度,在ESRI’S ARCGIS 8和FRAGSTATS 3.3软件支持下,系统研究了景观元素空间格局的变化。结果表明在近32年的时间进程中,区域森林景观破碎化现象加剧,其中以红松(Pinus koraiensis)林的破碎化最为严重。从斑块多样性、格局多样性和类型多样性的动态变化分析看出,原生的景观斑块类型在数量上不断减少或被异类景观所代替,即景观类型所占景观表面的百分比发生了变化,从而引起景观内部空间格局的改变。整个森林的景观多样性和景观类型分布的均匀性降低,优势度增加。人类不合理的经济活动,如毁林开荒、乱砍滥伐等,改变了景观异质性,从而造成景观多样性的变化。现在应该把对森林的保护和经营提到日程上来。天然林保护工程的实施对于促进林业部门休养生息、培育与保护森林资源,保护生物多样性和改善生态环境等具有重要意义。保护现有森林资源,实行采育结合,实施天然林保护工程,使森林的经营走可持续发展的道路是切实可行的解决办法. 相似文献
57.
P. Favetta J. Guitton N. Bleyzac C. Dufresne J. Bureau 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2001,751(2):755
A method using reversed-phase high-performance liquid chromatography with electrochemical detection for the analysis of vancomycin in human plasma was developed. Chromatographic conditions included an octadecyl column, a mobile phase of acetonitrile–sodium phosphate buffer (pH 7) (12:88), a total run time of 12 min, and coulometric electrochemical detection at +700 mV. Linear detector response was found in the range 5–100 μg ml−1 after a 1:80 dilution or from 0.5 to 50 μg ml−1 after a 1:20 dilution of the samples. In both cases the correlation coefficient (r) of the calibration curve standard was better than 0.995. Vancomycin determination was based on a denaturation of plasma proteins with methanol, then a dilution with mobile phase was performed. Recovery of vancomycin from plasma was 103.1±3.9%, and no interference from commonly used drugs or endogenous compounds was observed. A significant correlation was shown with the EMIT assay (r=0.92, P<0.001) using clinical samples from children. This HPLC technique is simple, sensitive, rapid, precise, selective and requires only 100 μl of plasma for completion. 相似文献
58.
Inter-MITE polymorphisms (IMP): a high throughput transposon-based genome mapping and fingerprinting approach 总被引:9,自引:0,他引:9
R.-Y. Chang L. S. O’Donoughue T. E. Bureau 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2001,102(5):773-781
Miniature inverted-repeat transposable elements or MITEs represent a large superfamily of transposons that are moderately
to highly repetitive and frequently associated with plant genes. These attributes were exploited in the development of a powerful
marker technology called Inter-MITE polymorphism, or IMP, which involves the amplification between two adjacent MITEs. In
this report, we describe the utility of the IMP approach in the mapping and fingerprinting of the barley genome. MITEs were
systematically mined from barley genomic gene sequences by computer-assisted database searches and structural analysis. Barley
MITEs include members of the Stowaway family and a new family we have named Barfly. Using these barley MITEs, a total of 88 IMP markers were mapped onto an existing barley RFLP map that was based on a doubled-haploid
segregating population between Hordeum vulgare and Hordeum spontaneum. We demonstrate that the IMP approach can be effectively applied in the fingerprinting of barley cultivars and for genetic
similarity analysis. We also provide evidence that barley MITE-based primers can be effectively used in the mapping and fingerprinting
of other cereals, suggesting that the IMP approach has broad applicability.
Received: 24 March 2000 / Accepted: 28 July 2000 相似文献
59.
60.
Rebekah van Bruggen Christian Gualtieri Alexandra Iliescu Chalisa Louicharoen Cheepsunthorn Punchalee Mungkalasut Jean-Fran?ois Trape David Modiano Bienvenu Sodiomon Sirima Pratap Singhasivanon Mark Lathrop Anavaj Sakuntabhai Jean-Fran?ois Bureau Philippe Gros 《PloS one》2015,10(12)
Pyruvate kinase (PKLR) is a critical erythrocyte enzyme that is required for glycolysis and production of ATP. We have shown that Pklr deficiency in mice reduces the severity (reduced parasitemia, increased survival) of blood stage malaria induced by infection with Plasmodium chabaudi AS. Likewise, studies in human erythrocytes infected ex vivo with P. falciparum show that presence of host PK-deficiency alleles reduces infection phenotypes. We have characterized the genetic diversity of the PKLR gene, including haplotype structure and presence of rare coding variants in two populations from malaria endemic areas of Thailand and Senegal. We investigated the effect of PKLR genotypes on rich longitudinal datasets including haematological and malaria-associated phenotypes. A coding and possibly damaging variant (R41Q) was identified in the Thai population with a minor allele frequency of ~4.7%. Arginine 41 (R41) is highly conserved in the pyruvate kinase family and its substitution to Glutamine (R41Q) affects protein stability. Heterozygosity for R41Q is shown to be associated with a significant reduction in the number of attacks with Plasmodium falciparum, while correlating with an increased number of Plasmodium vivax infections. These results strongly suggest that PKLR protein variants may affect the frequency, and the intensity of malaria episodes induced by different Plasmodium parasites in humans living in areas of endemic malaria. 相似文献