全文获取类型
收费全文 | 606篇 |
免费 | 33篇 |
出版年
2023年 | 3篇 |
2022年 | 6篇 |
2021年 | 7篇 |
2020年 | 5篇 |
2019年 | 4篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 12篇 |
2015年 | 31篇 |
2014年 | 36篇 |
2013年 | 43篇 |
2012年 | 43篇 |
2011年 | 40篇 |
2010年 | 38篇 |
2009年 | 38篇 |
2008年 | 32篇 |
2007年 | 32篇 |
2006年 | 27篇 |
2005年 | 28篇 |
2004年 | 40篇 |
2003年 | 29篇 |
2002年 | 36篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 9篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1988年 | 2篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1971年 | 1篇 |
1968年 | 2篇 |
1964年 | 2篇 |
1962年 | 1篇 |
1944年 | 1篇 |
排序方式: 共有639条查询结果,搜索用时 15 毫秒
91.
92.
Vitaly N. Nikandrov Oleg N. Murashko Galina V. Vorobyova Nelly S. Pyzhova Natalie V. Kvyatkovskaya Oksana A. Bartalevich 《International journal of peptide research and therapeutics》1997,4(4-6):497-502
Summary The formation of stable equimolar complexes of streptokinase or plasminogen with muscle lactate dehydrogenase or pyruvate
kinase, heart mitochondrial malate dehydrogenase and hepatic catalase at pH 7.4, 3.0 and 10.0 was first detected by differential
spectroscopy methods. All complexes, except those of plasminogen with dehydrogenases, were resistant to 6 M urea. Judging
from circular dichroism spectra, tertiary and secondary structures were considerably changed in the complexes. These changes
were significantly dependent upon the nature of interacting proteins; in some cases their structures were more ordered. NAD
(but not NADH) hampered the formation of streptokinase complexes with dehydrogenases. The plasminogen-activating function
of streptokinase and the ability of plasminogen to be activated by streptokinase in the complexes with oxidoreductases were
essentially unchanged. Pyruvate kinase induced a moderate (by 35%) increase in the streptokinase activating function. It is
assumed that the formation of complexes of streptokinase or plasminogen with enzymes may serve as a link in metabolic regulation
and/or intercellular interactions. 相似文献
93.
94.
Haliotis tuberculata mortality outbreaks have occurred in France since 1998 and were attributed to a pathogenic Vibrio harveyi. These mortalities were recorded in September, a month with abalone reproduction and characterised by high seawater temperatures. The importance of gonadal maturation and temperature increase on abalone immunity and susceptibility to V. harveyi infection needed to be clarified. Therefore, an immune survey analyzing a large panel of parameters was performed from June to September 2007 on abalone from the Bay of Brest. The data obtained were put in relation with abalone reproductive status and its susceptibility to V. harveyi. Most parameters showed clear patterns from early to late summer and during gametogenesis, phagocytosis and phenoloxidase activity were reduced, whereas basal reactive oxygen species production and agglutination titres were significantly increased. Total haemocyte counts went up after the partial spawning event at the end of June, and cell complexity diminished. Using a Principal Component Analysis, the "haemolymph profile" was shown to decrease in parallel with spawning and gonadal maturation processes, and reached a minimum just after total spawning. A significant correlation between this "haemolymph profile" and disease susceptibility allowed us to establish for the first time in abalone, a clear concordance between maturation and spawning processes, immune status and abalone susceptibility to V. harveyi. 相似文献
95.
Singh BN Hayes GR Lucas JJ Sommer U Viseux N Mirgorodskaya E Trifonova RT Sassi RR Costello CE Fichorova RN 《Glycoconjugate journal》2009,26(1):3-17
Trichomonas vaginalis causes the most common non-viral sexually transmitted infection linked to increased risk of premature birth, cervical cancer
and HIV. This study defines molecular domains of the parasite surface glycoconjugate lipophosphoglycan (LPG) with distinct
functions in the host immunoinflammatory response. The ceramide phospho-inositol glycan core (CPI-GC) released by mild acid
had Mr of ∼8,700 Da determined by MALDI-TOF MS. Rha, GlcN, Gal and Xyl and small amounts of GalN and Glc were found in CPI-GC.
N-acetyllactosamine repeats were identified by endo-β-galactosidase treatment followed by MALDI-MS and MS/MS and capLC/ESI-MS/MS analyses. Mild acid hydrolysis led to products
rich in internal deoxyhexose residues. The CPI-GC induced chemokine production, NF-κB and extracellular signal-regulated kinase
(ERK)1/2 activation in human cervicovaginal epithelial cells, but neither the released saccharide components nor the lipid-devoid
LPG showed these activities. These results suggest a dominant role for CPI-GC in the pathogenic epithelial response to trichomoniasis. 相似文献
96.
Investigation of the antifouling constituents from the brown alga Sargassum muticum (Yendo) Fensholt
Alexandra Bazes Alla Silkina Philippe Douzenel Fabienne Faÿ Nelly Kervarec Danièle Morin Jean-Pascal Berge Nathalie Bourgougnon 《Journal of applied phycology》2009,21(4):395-403
One of the most promising alternatives to toxic heavy metal-based paints is offered by the development of antifouling coatings
in which the active ingredients are compounds naturally occurring in marine organisms and operating as natural antisettlement
agents. Sessile marine macroalgae are remarkably free from settlement by fouling organisms. They produce a wide variety of
chemically active metabolites in their surroundings, potentially as an aid to protect themselves against other settling organisms.
In this study, a dichloromethane extract from the brown seaweed Sargassum muticum was tested in situ and, after 2 months of immersion, showed less fouling organisms on paints in which the extract was included,
compared to paints containing only copper after 2 months of immersion. No barnacles or mussels have been observed on the test
rack. Identification by NMR and GC/MS of the effective compound revealed the abundance of palmitic acid, a commonly found
fatty acid. Pure palmitic acid showed antibacterial activity at 44 μg mL−1, and also inhibited the growth of the diatom Cylindrotheca closterium at low concentration (EC50 = 45.5 μg mL−1), and the germination of Ulva lactuca spores at 3 μg mL−1. No cytotoxicity was highlighted, which is promising in the aim of the development of an environmentally friendly antifouling
paint. 相似文献
97.
98.
Lyubov Yotova Irene Tzibranska Filadia Tileva G. H. Markx Nelly Georgieva 《Journal of industrial microbiology & biotechnology》2009,36(3):367-372
A simple method for the preparation of the biocatalyst with whole cells is presented, and the applicability of the technique
for biodegradation of phenol in wastewater from the chemical industries using the basidomycetes yeast Trichosporon cutaneum is explored. Kinetic studies of the influence of other compounds contained in wastewater as naphthalene, benzene, toluene
and pyridine indicate that apart from oil fraction, which is removed, the phenol concentration is the only major factor limiting
the growth of immobilized cells. Mathematical models are applied to describe the kinetic behavior of immobilized yeast cells.
From the analysis of the experimental curves was shown that the obtained values for the apparent rate parameters vary depending
on the substrate concentration (μmaxapp from 0.35 to 0.09 h−1 and K
sapp from 0.037 to 0.4 g dm−3). The inhibitory effect of the phenol on the obtained yield coefficients was investigated too. It has been shown that covalent
immobilization of T. cutaneum whole cells to plastic carrier beads is possible, and that cell viability and phenol degrading activity are maintained after
the chemical modification of cell walls during the binding procedure. The results obtained indicate a possible future application
of immobilized T. cutaneum for destroying phenol in industrial wastewaters. 相似文献
99.
100.
Guillain Mikaty Magali Soyer Emilie Mairey Nelly Henry Dave Dyer Katrina T. Forest Philippe Morand Stéphanie Guadagnini Marie Christine Prévost Xavier Nassif Guillaume Duménil 《PLoS pathogens》2009,5(2)
Bacterial infections targeting the bloodstream lead to a wide array of devastating diseases such as septic shock and meningitis. To study this crucial type of infection, its specific environment needs to be taken into account, in particular the mechanical forces generated by the blood flow. In a previous study using Neisseria meningitidis as a model, we observed that bacterial microcolonies forming on the endothelial cell surface in the vessel lumen are remarkably resistant to mechanical stress. The present study aims to identify the molecular basis of this resistance. N. meningitidis forms aggregates independently of host cells, yet we demonstrate here that cohesive forces involved in these bacterial aggregates are not sufficient to explain the stability of colonies on cell surfaces. Results imply that host cell attributes enhance microcolony cohesion. Microcolonies on the cell surface induce a cellular response consisting of numerous cellular protrusions similar to filopodia that come in close contact with all the bacteria in the microcolony. Consistent with a role of this cellular response, host cell lipid microdomain disruption simultaneously inhibited this response and rendered microcolonies sensitive to blood flow–generated drag forces. We then identified, by a genetic approach, the type IV pili component PilV as a triggering factor of plasma membrane reorganization, and consistently found that microcolonies formed by a pilV mutant are highly sensitive to shear stress. Our study shows that bacteria manipulate host cell functions to reorganize the host cell surface to form filopodia-like structures that enhance the cohesion of the microcolonies and therefore blood vessel colonization under the harsh conditions of the bloodstream. 相似文献