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51.
Chi ZH Wang X Cai JQ Stoltenberg M Danscher G Wang ZY 《Neurochemistry international》2008,52(7):1305-1309
Zinc transporter 3 (ZNT3) has been shown to transport zinc ions from the cytosol into presynaptic vesicles in the mammalian brain. Several studies have stated that the zinc ion containing synaptic vesicles of zinc-enriched neurons (ZEN) are loaded with ZNT3 proteins in their membranes. This fact makes it possible to trace sprouting mossy fibres in the temporal lobe epileptic hippocampus. In the present study, we examined the expression and distribution patterns of ZNT3 protein and chelatable zinc ions in the mouse hippocampus after pilocarpine treatment. Our results demonstrate that both ZNT3 immunostaining and autometallography reveal identical patterns of sprouting mossy fibres in the inner molecular layer in the mouse hippocampus. Using ZNT3 immuno-electron microscopic analysis we confirmed the presence of ectopic mossy fibre terminals in the inner molecular layer and found additionally by immuno-blotting a significant increase of ZNT3 in the pilocarpine-treated mouse hippocampi compared to age-matched controls. The increase of ZNT3 after pilocarpine treatment was time-dependent. The results support the notion that ZNT3 immunohistochemistry provides an excellent tool for tracing sprouting of ZEN terminals. The progressive increase of ZNT3 immunostaining in the temporal lobe epileptic hippocampus may relate to the increased levels of vesicular zinc ions during seizure. 相似文献
52.
Pørksen N Grøfte T Greisen J Mengel A Juhl C Veldhuis JD Schmitz O Rössle M Vilstrup H 《American journal of physiology. Endocrinology and metabolism》2002,282(3):E695-E702
Insulin is secreted as a series of punctuated secretory bursts superimposed on variable basal insulin release. The contribution of these secretory bursts to overall insulin secretion has been estimated on the basis of peripheral vein sampling in humans to encompass > or =75% of overall insulin release. A similar contribution of the pulsatile mode of release was inferred in a canine model by use of portal vein sampling. The primary regulation of insulin secretion is through perturbation of the mass and frequency of these secretory bursts. The mode of delivery of insulin into the circulation seems important for insulin action; therefore, physiological conditions that alter the pattern of insulin release may affect insulin action through this mechanism. Transhepatic intraportal shunt in humans may provide access to portal vein samples, thus potentially improving the sensitivity of detecting and quantitating the frequency, mass, and amplitude of secretory bursts along with basal release and the regularity of these variables. To establish the insulin-secretory mechanism in nondiabetic humans by the use of portal vein sampling, we here assessed the mass, frequency, amplitude, and overall contribution of pulsatile insulin secretion by deconvolution analysis of portal vein insulin profiles. We find that, in nondiabetic humans fasted overnight, the portal vein insulin concentration oscillates at a periodicity of 4.1 +/- 0.2 min/pulse and with secretory peak amplitudes averaging 660% of basal (interpulse) release. The frequency was confirmed by spectral and autocorrelation analyses. The punctuated insulin-secretory bursts partially overlap and are responsible for the majority (70 +/- 4%) of insulin release. After ingestion of a mixed meal, the insulin release was increased through amplification of the secretory burst mass (507 +/- 104 vs. 1,343 +/- 211 pmol x l(-1) x min(-1), P < 0.001), whereas frequency (4.4 +/- 0.2 vs. 4.3 +/- 0.2, P = 0.86) and basal secretion (62 +/- 14 vs. 91 +/- 22 pmol x l(-1) x min(-1), P = 0.33) were unaffected. One subject with diabetes and cirrhosis had a similar insulin-secretory pattern, whereas a subject with insulin-dependent diabetes mellitus and minimal insulin release had preserved pulsatile release. A single subject was entrained to show agreement between entrained frequency and portal vein insulin oscillations. We conclude that insulin release in the human portal vein occurs at a mean periodicity of 4.4 +/- 0.2 min with a high signal-to-noise ratio (pulse amplitude 660% of basal). The impact of noise on the detected high frequency cannot be excluded. 相似文献
53.
Mikkelsen NE Johansson K Karlsson A Knecht W Andersen G Piskur J Munch-Petersen B Eklund H 《Biochemistry》2003,42(19):5706-5712
Deoxyribonucleoside kinases are feedback inhibited by the final products of the salvage pathway, the deoxyribonucleoside triphosphates. In the present study, the mechanism of feedback inhibition is presented based on the crystal structure of a complex between the fruit fly deoxyribonucleoside kinase and its feedback inhibitor deoxythymidine triphosphate. The inhibitor was found to be bound as a bisubstrate inhibitor with its nucleoside part in the nucleoside binding site and with its phosphate groups partially occupying the phosphate donor site. The overall structure of the enzyme--inhibitor complex is very similar to the enzyme--substrate complexes with deoxythymidine and deoxycytidine, except for a conformational change within a region otherwise directly involved in catalysis. This conformational change involves a magnesium ion, which is coordinated in the inhibitor complex to the phosphates and to the primary base, Glu52, that normally is positioned close to the 5'-OH of the substrate deoxyribose. 相似文献
54.
Comparative genomics reveals novel biochemical pathways 总被引:2,自引:0,他引:2
How well do we understand which enzymes are involved in the primary metabolism of the cell? A recent study using comparative genomics and postgenomics approaches revealed a novel pathway in the most studied organism, Escherichia coli. The analysis of a new operon consisting of seven previously uncharacterized genes thought to be involved in the degradation of nucleic acid precursors shows the impact of comparative genomics on the discovery of novel pathways and enzymes. 相似文献
55.
This paper investigates effects of combining thermal and biological remediation, based on laboratory studies of trichloroethene
(TCE) degradation. Aquifer material was collected 6 months after terminating a full-scale Electrical Resistance Heating (ERH),
when the site had cooled from approximately 100°C to 40°C. The aquifer material was used to construct bioaugmented microcosms
amended with the mixed anaerobic dechlorinating culture, KB-1TM, and an electron donor (5 mM lactate). Microcosms were bioaugmented during cooling at 40, 30, 20, and 10°C, as temperatures
continually decreased during laboratory incubation. Redox conditions were generally methanogenic, and electron donors were
present to support dechlorination. For microcosms bioaugmented at 10°C and 20°C, dechlorination stalled at cis-dichloroethene (cDCE) and vinyl chloride (VC) 150 days after bioaugmentation. However, within 300 days of incubation ethene was produced in
the majority of these microcosms. In contrast, dechlorination was rapid and complete in microcosms bioaugmented at 30°C. Microcosms
bioaugmented at 40°C also showed rapid dechlorination, but stalled at cDCE with partial VC and ethene production, even after 150 days of incubation when the temperature had decreased to 10°C. These
results suggest that sequential bioremediation of TCE is possible in field-scale thermal treatments after donor addition and
bioaugmentation and that the optimal bioaugmentation temperature is approximately 30°C. When biological and thermal remediations
are to be applied at the same location, three bioremediation approaches could be considered: (a) treating TCE in perimeter
areas outside the source zone at temperatures of approximately 30°C; (b) polishing TCE concentrations in the original source
zone during cooling from approximately 30°C to ambient groundwater temperatures; and (c) using bioremediation in downgradient
areas taking advantages of the higher temperature and potential release of organic matter. 相似文献
56.
Summary In order to visualize the vascular system of the rat brain, 10 Wistar rats were perfused transcardially with glutaraldehyde
and a 40°C gold-gelatine solution. The brains were post-fixed with glutaraldehyde and vibratomized into 100-μm-thick slices,
and the gold particles were developed by autometallography. In this way, the colloidal gold particles in the vessels became
encased in silver and thereby made visible. The developed gold staining is stable and does not interfere with further dehydration
and counterstaining. Images were frame grabbed during optical slicing, and classic stereograms and ‘shadow’ 3-D images were
produced. We found a high variation of capillary density in the hippocampal region reflecting known subregional structures.
The silver-enhanced vessels acted as natural markers and made it possible to study and measure aspects of the complexity of
dehydration and staining artifacts. We found a non-linear shrinking of 13–17% in the x- and y-directions and a spatial shrinking up to 50% in some regions after the dehydration and staining process. This observation
may be of interest not only in relation to tissue subjected to this fixation protocol but also to other fixation procedures.
The gold-gelatine autometallographic technique and the present stereograms can release data for stereological use as well
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
57.
58.
Histochemical demonstration of zinc ions in human epididymis using autometallography 总被引:1,自引:0,他引:1
Meredin Stoltenberg Lars Lund Soren Juhl Gorm Danscher Erik Ernst 《Journal of molecular histology》1997,29(10):721-726
Summary A recently described autometallographic technique, allowing demonstration of chelatable zinc in human biopsy material, was
applied to cryostat sections from biopsies of human epididymis. Sections from the rat epididymis were used as control materials
to examine the quality of the method compared with a previously used autometallographic method. The human epididymis exhibits
heavy staining in the head of the epididymis and only small amounts of zinc in the body and tail of the organ. The zinc staining
was found in the apical part of the ciliated cells and in the lumen. The present technique can be used to localize zinc ions
at ultrastructural levels. Zinc grains were localized in lysosome-like bodies and secretory granules of the ciliated cells.
The luminal staining was present as free, evenly dispersed zinc grains or attached to sperm cells and stereocilia in the lumen.
The large differences in staining patterns along the epididymal tract in humans and rats suggest that zinc ions are important
for the maturation of sperm cells
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
59.
Pinto VV Ditlev SB Jensen KE Resende M Dahlbäck M Andersen G Andersen P Theander TG Salanti A Nielsen MA 《PloS one》2011,6(3):e17942
Background
In Plasmodium falciparum malaria endemic areas placental malaria (PM) is an important complication of malaria. The recurrence of malaria in primigravidae women irrespective of acquired protection during childhood is caused by the interaction between the parasite-expressed VAR2CSA antigen and chondroitin sulfate A (CSA) in the placental intervillous space and lack of protective antibodies. PM impairs fetal development mainly by excessive inflammation processes. After infections during pregnancy women acquire immunity to PM conferred by antibodies against VAR2CSA. Ideally, a vaccine against PM will induce antibody-mediated immune responses that block the adhesion of infected erythrocytes (IE) in the placenta.Principal Findings
We have previously shown that antibodies raised in rat against individual domains of VAR2CSA can block IE binding to CSA. In this study we have immunized mice, rats and rabbits with each individual domain and the full-length protein corresponding to the FCR3 VAR2CSA variant. We found there is an inherently higher immunogenicity of C-terminal domains compared to N-terminally located domains. This was irrespective of whether antibodies were induced against single domains or the full-length protein. Species-specific antibody responses were also found, these were mainly directed against single domains and not the full-length VAR2CSA protein.Conclusions/Significance
Binding inhibitory antibodies appeared to be against conformational B-cell epitopes. Non-binding inhibitory antibodies reacted highly against the C-terminal end of the VAR2CSA molecule especially the highly polymorphic DBL6ε domain. Differential species-specific induction of antibody responses may allow for more direct analysis of functional versus non-functional B-cell epitopes. 相似文献60.
The sensitivity and specificity of clinical diagnostic assays using DNA hybridization techniques are limited by the dissociation of double-stranded DNA (dsDNA) antiparallel duplex helices. This situation can be improved by addition of DNA stabilizing molecules such as nucleic acid intercalators. Here, we report the synthesis of a novel ortho-Twisted Intercalating Nucleic Acid (TINA) amidite utilizing the phosphoramidite approach, and examine the stabilizing effect of ortho- and para-TINA molecules in antiparallel DNA duplex formation. In a thermal stability assay, ortho- and para-TINA molecules increased the melting point (Tm) of Watson-Crick based antiparallel DNA duplexes. The increase in Tm was greatest when the intercalators were placed at the 5' and 3' termini (preferable) or, if placed internally, for each half or whole helix turn. Terminally positioned TINA molecules improved analytical sensitivity in a DNA hybridization capture assay targeting the Escherichia coli rrs gene. The corresponding sequence from the Pseudomonas aeruginosa rrs gene was used as cross-reactivity control. At 150 mM ionic strength, analytical sensitivity was improved 27-fold by addition of ortho-TINA molecules and 7-fold by addition of para-TINA molecules (versus the unmodified DNA oligonucleotide), with a 4-fold increase retained at 1 M ionic strength. Both intercalators sustained the discrimination of mismatches in the dsDNA (indicated by ΔTm), unless placed directly adjacent to the mismatch--in which case they partly concealed ΔTm (most pronounced for para-TINA molecules). We anticipate that the presented rules for placement of TINA molecules will be broadly applicable in hybridization capture assays and target amplification systems. 相似文献