全文获取类型
收费全文 | 171篇 |
免费 | 9篇 |
出版年
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 3篇 |
2019年 | 10篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 5篇 |
2015年 | 10篇 |
2014年 | 12篇 |
2013年 | 8篇 |
2012年 | 11篇 |
2011年 | 12篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 5篇 |
2007年 | 7篇 |
2006年 | 3篇 |
2005年 | 7篇 |
2004年 | 5篇 |
2003年 | 8篇 |
2002年 | 3篇 |
2001年 | 4篇 |
2000年 | 8篇 |
1999年 | 4篇 |
1998年 | 8篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1971年 | 1篇 |
1966年 | 1篇 |
1960年 | 2篇 |
1927年 | 1篇 |
排序方式: 共有180条查询结果,搜索用时 15 毫秒
121.
122.
123.
124.
Annemarie MM Vlaar Tjerk de Nijs Marinus JPG van Kroonenburgh Werner H Mess Ania Winogrodzka Selma C Tromp Wim EJ Weber 《BMC neurology》2008,8(1):42
Background
Transcranial duplex sonography (TCD) of the substantia nigra has emerged as a promising, non-invasive tool to diagnose idiopathic Parkinson's disease (IPD). However, its diagnostic accuracy in patients with undefined parkinsonism remains to be determined. 相似文献125.
The interaction of the hepatitis G synthetic peptide E2(99-118) with cell membrane phospholipids of different characteristics such as dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG) was studied by Langmuir isotherms. Epifluorescence microscopy and Atomic force microscopy (AFM) was also used to study interactions with DPPC. Compression isotherms of DPPC/E2(99-118) and DPPG/E2(99-118) mixed monolayers showed negative deviation from ideallity consistent with the existence of attractive interactions. The incorporation of the peptide in DPPC monolayer was also confirmed in epifluorescence microscopy and AFM studies. The peptide retarded the formation of DPPC domains and did not let the phospholipid get organized. No important differences in the interactions with DPPC (neutral) or DPPG (anionic) were found, thus suggesting that electrostatics forces do not have a predominant influence in these interactions. 相似文献
126.
To establish correlation between structural properties (charge, composition, and conformation) and membrane penetration capability, the interaction of epitope peptide-carrier constructs with phospholipid model membranes was studied. For this we have conjugated a linear epitope peptide, (110)FWRGDLVFDFQV(121) (110-121), from VP3 capside protein of the Hepatitis A virus with polylysine-based branched polypeptides with different chemical characteristics. The epitope peptide elongated by one Cys residue at the N-terminal [C(110-121)] was attached to poly[Lys-(DL-Ala(m)()-X(i)())] (i < 1, m approximately 3), where x = ?(AK), Ser (SAK), or Glu (EAK) by the amide-thiol heterobifunctional reagent, 3-(2-pyridyldithio)propionic acid N-hydroxy-succinimide ester. The interaction of these polymer-[C(110-121)] conjugates with phospholipid monolayers and bilayers was studied using DPPC and DPPC/PG (95/5 mol/mol) mixture. Changes in the fluidity of liposomes induced by these conjugates were detected by using two fluorescent probes 1,6-diphenyl-1,3, 5-hexatriene (DPH) and sodium anilino naphthalene sulfonate (ANS). The binding of conjugates to the model membranes was compared and the contribution of the polymer component to these interactions were evaluated. We found that conjugates with polyanionic/EAK-[C(110-121)] or polycationic/SAK-[C(110-121)], AK-[C(110-121)]/character were capable to form monomolecular layers at the air/water interface with structure dependent stability in the following order: EAK-[C(110-121)] > SAK-[C(110-121)] > AK-[C(110-121)]. Data obtained from penetration studies into phospholipid monolayers indicated that conjugate insertion is more pronounced for EAK-[C(110-121)] than for AK-[C(110-121)] or SAK-[C(110-121)]. Changes in the fluorescence intensity and in polarization of fluorescent probes either at the polar surface (ANS) or within the hydrophobic core (DPH) of the DPPC/PG liposomes suggested that all three conjugates interact with the outer surface of the bilayer. Marked penetration was documented by a significant increase of the transition temperature only with the polyanionic compound/EAK-[C(110-121)]. Taken together, we found that the binding/penetration of conjugates to phospholipid model membranes is dependent on the charge properties of the constructs. Considering that the orientation and number of VP3 epitope peptides attached to branched polypeptides were almost identical, we can conclude that the structural characteristics (amino acid composition, charge, and surface activity) of the carrier have a pronounced effect on the conjugate-phospholipid membrane interaction. These observations suggest that the selection of polymer carrier for epitope attachment might significantly influence the membrane activity of the conjugate and provide guidelines for adequate presentation of immunogenic peptides to the cells. 相似文献
127.
Larios C Casas J Alsina MA Mestres C Gómara MJ Haro I 《Archives of biochemistry and biophysics》2005,442(2):149-159
With the aim of better understanding the fusion process mediated by the envelope proteins of the hepatitis G virus (HGV/GBV-C), we have investigated the interaction with model membranes of two overlapping peptides [(267-284) and (279-298)] belonging to the E2 structural protein. The peptides were compared for their ability to perturb lipid bilayers by means of different techniques such as differential scanning calorimetry and fluorescence spectroscopy. Furthermore, the conformational behaviour of the peptides in different membrane environments was studied by Fourier-transform infrared spectroscopy and circular dichroism. The results showed that only the E2(279-298) peptide sequence was able to bind with high affinity to negatively charged membranes, to permeabilize efficiently negative lipid bilayers, to induce haemolysis, and to promote inter-vesicle fusion. This fusogenic activity could be related to the induced peptide conformation upon interaction with the target membrane. 相似文献
128.
A peptide sequence, stearoyl-GESIKVAVS(NH2), related to a laminin fragment, has been synthesized. Formation of aggregates was controlled by titrating a sodium anilinonaphthalene sulphonate (ANS) solution with peptide and recording fluorescence intensity increases. The results show that this system experiences a sudden increase in fluorescence at peptide concentrations around 2.5 x 10(-4) mol/L. The interaction of this hydrophobic peptide with DPPC vesicles has been studied using fluorescence techniques. Its influence on the microviscosity of bilayers was determined by studying polarization/temperature dependence for ANS and diphenyl hexatriene (DPH) fluorescent probes. With both markers the presence of peptide promotes a clear increase in anisotropy values. This indicates a rigidifying effect. Leakage studies carried out with liposomes loaded with carboxyfluorescein (CF) indicate a stabilizing effect of the peptide on bilayers, in agreement with results obtained with fluorescent probes. 相似文献
129.
Sterigmatocystin (STG) is a toxic metabolite produced by severalAspergillus species. Because of its toxic and carcinogenic properties the occurrence of STG in food is considered to represent a potential
hazard to man. The present study was designed to investigate following points:
相似文献
1 | A survey of STG incidence in Ras cheese on local markets. Ras cheese samples were collected from Cairo, Giza and Kalubia governorates. Thirty five percent of the samples contained the toxin with a mean value of 22.23 μg /kg |
2 | Fate of STG contaminating milk during Ras cheese processing. Milk was artificially contaminated with 125 μg/kg and processed into Ras cheese. Eighty percent of the toxin was distributed into the curd and 20% into the whey. Cheese ripening effected toxin content and the effect was temperature dependent. At 6°C: toxin concentration was slightly affected; at 20°C the toxin was reduced by 16% after 90 days when low toxin concentration was used. |
3 | Formation of STG byA versicolor mold on Ras cheese. Ras cheese blocks were contaminated with spores of the mold. Toxin production started after 45 days of ripening and reached a maximum at 90 days and then declined. Cow’s milk favoured toxin production over buffaloe’s. Aged cheese inhibited toxin production. |
130.
Howe GT; Bucciaglia PA; Hackett WP; Furnier GR; Cordonnier-Pratt MM; Gardner G 《Molecular biology and evolution》1998,15(2):160-175
The phytochrome photoreceptors play important roles in the photoperiodic
control of vegetative bud set, growth cessation, dormancy induction, and
cold-hardiness in trees. Interestingly, ecotypic differences in
photoperiodic responses are observed in many temperate- zone tree species.
Northern and southern ecotypes of black cottonwood (Populus trichocarpa
Torr. & Gray), for example, exhibit marked differences in the timing of
short-day-induced bud set and growth cessation, and these responses are
controlled by phytochrome. Therefore, as a first step toward determining
the molecular genetic basis of photoperiodic ecotypes in trees, we
characterized the phytochrome gene (PHY) family in black cottonwood. We
recovered fragments of one PHYA and two PHYB using PCR-based cloning and by
screening a genomic library. Results from Southern analyses confirmed that
black cottonwood has one PHYA locus and two PHYB loci, which we arbitrarily
designated PHYB1 and PHYB2. Phylogenetic analyses which included PHY from
black cottonwood, Arabidopsis thaliana and tomato (Solanum lycopersicum)
suggest that the PHYB/D duplications in these species occurred
independently. When Southern blots were probed with PHYC, PHYE, and PHYE
heterologous probes, the strongest bands that we detected were those of
black cottonwood PHYA and/or PHYB. These results suggest that black
cottonwood lacks members of the PHYC/F and PHYE subfamilies. Although black
cottonwood could contain additional PHY that are distantly related to known
angiosperm PHY, our results imply that the PHY family of black cottonwood
is less complex than that of other well-characterized dicot species such as
Arabidopsis and tomato. Based on Southern analyses of five black cottonwood
genotypes representing three photoperiodic ecotypes, substantial
polymorphism was detected for at least one of the PHYB loci but not for the
PHYA locus. The novel character of the PHY family in black cottonwood, as
well as the differences in polymorphism we observed between the PHYA and
PHYB subfamilies, indicates that a number of fundamental macro- and
microevolutionary questions remain to be answered about the PHY family in
dicots.
相似文献