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111.
Summary The histochemical and cytochemical localization of cholinesterases in Bidder's ganglion of the frog heart was investigated and the activity of cholinesterases measured microgasometrically.When either acetylthiocholine or propionylthiocholine was used as substrate, the end product of histochemical and cytochemical reaction was found in all ganglion cells and nerve fibers, the only difference being in the amount of the accumulated precipitate. The end product was localized on the axolemma and in the smooth endoplasmic reticulum of nerve fibers; in the smooth and granulated endoplasmic reticulum of ganglion cells; in the synaptic region between the nerve ending and Schwann cells membrane; and, occasionally, in discontinous streches between the pre- and postsynaptic membrane. The nerve endings of the neurons of the Bidder's ganglion contain predominantly agranular vesicles with occasional clusters of granular ones.Neither the histochemical nor the cytochemical localization of enzyme activity could be detected when butyrylthiocholine was used as substrate. In microgasometric experiments splitting of butyrylcholine was hardly, if at all, measurable. Cholinesterases of the ganglion cells and of the nerve fibers of Bidder's ganglion hydrolyze propionylcholine but at a somewhat lower rate than acetylcholine.A part of this work has been presented at the VI. Congress of the Yugoslav Physiological Society, Ohrid, 1969.This work was supported by the Boris Kidri Foundation, Ljubljana, and by the Federal Research Council, Beograd. 相似文献
112.
Abstract— Isolated endplate regions from the mouse diaphragm were treated with different agents before or after homogenization in order to solubilize junctional AChE and study the effect of solubilization on its apparent activity. Total AChE activity (solubilized + nonsolubilized) of samples treated with collagenase or papain before homogenization was nearly twice as high as in control samples. If collagenase was added after homogenization no increase in apparent activity was observed although in both cases about 70–80% of AChE activity was solubilized. The access of ACh to the membrane-bound enzyme is probably not a limiting factor in the AChE assay as is the case in the electric organ homogenates. Both 1 m -NaCl and Triton X-100 were quite ineffective as solubilizers when applied before homogenization and had an insignificant effect on the apparent AChE activity.
The increase in apparent AChE activity cannot be explained either by a de novo synthesis or by the change in kinetic properties of different species of AChE, or by the release of AChE possibly sequestrated in the membrane vesicles. The possibility is discussed that a part of junctional AChE is inactivated at the beginning of homogenization while it can be preserved by previous solubilization, or that proteolytic treatment may activate some 'silent' AChE sites in motor endplates.
However, the mere fact that the difference does exist suggests that all AChE activity present in intact motor endplates may not be measurable after homogenization. 相似文献
The increase in apparent AChE activity cannot be explained either by a de novo synthesis or by the change in kinetic properties of different species of AChE, or by the release of AChE possibly sequestrated in the membrane vesicles. The possibility is discussed that a part of junctional AChE is inactivated at the beginning of homogenization while it can be preserved by previous solubilization, or that proteolytic treatment may activate some 'silent' AChE sites in motor endplates.
However, the mere fact that the difference does exist suggests that all AChE activity present in intact motor endplates may not be measurable after homogenization. 相似文献
113.
Summary A comparison between the one-step and the two-step copper thiocholine procedure for the subcellular localization of cholinesterases was under-taken. The results indicate that only under experimental conditions with short incubation times and precise control of the conversion into sulphide is the localization of the primary precipitate and that of the secondary precipitate identical. It was concluded that the conversion of the primary precipitate into Cu-sulphide is not necessary and can lead to artefacts. 相似文献
114.
Biros E Bodnár J Biros I Birosová E Mojzis J Hrivnák M Klimcáková L Findlay I Mirossay A Mirossay L 《Folia microbiologica》2007,52(4):443-446
A simple nucleic acid amplification test (NAAT) was developed for detection of Ureaplasma urealyticum infection based on the PCR amplification of the urease gene (UU1/UU2 Test). DNA was extracted from urogenital swabs and a 225-bp long DNA fragment was amplified by PCR. NAAT was compared to the commercial amplification kit for sexually transmitted disease reference assay. The sensitivity and specificity of the UU1/UU2 Test were determined to be 100 and 98.9%, respectively. The overall prevalence rate in this group of patients was found to be about 236 per 1000 (283 and 166 per 1000 in females and males, respectively). These data demonstrate that UU1/UU2 Test is suitable for effective epidemiological screening and/or diagnostic practice. 相似文献
115.
Background and AimsQuantifying the Earth’s forest above-ground biomass (AGB) is indispensable for effective climate action and developing forest policy. Yet, current allometric scaling models (ASMs) to estimate AGB suffer several drawbacks related to model selection and uncertainties about calibration data traceability. Terrestrial laser scanning (TLS) offers a promising non-destructive alternative. Tree volume is reconstructed from TLS point clouds with quantitative structure models (QSMs) and converted to AGB with wood basic density. Earlier studies have found overall TLS-derived forest volume estimates to be accurate, but highlighted problems for reconstructing finer branches. Our objective was to evaluate TLS for estimating tree volumes by comparison with reference volumes and volumes from ASMs.MethodsWe quantified the woody volume of 65 trees in Belgium (from 77 to 2800 L; Pinus sylvestris, Fagus sylvatica, Larix decidua, and Fraxinus excelsior) with QSMs and destructive reference measurements. We tested a volume expansion factor (VEF) approach by multiplying the solid and merchantable volume from QSMs by literature VEF values.Key ResultsStem volume was reliably estimated with TLS. Total volume was overestimated by +21 % using original QSMs, by +9 % and –12 % using two sets of VEF-augmented QSMs, and by –7.3 % using best-available ASMs. The most accurate method differed per site, and the prediction errors for each method varied considerably between sites.ConclusionsVEF-augmented QSMs were only slightly better than original QSMs for estimating tree volume for common species in temperate forests. Despite satisfying estimates with ASMs, the model choice was a large source of uncertainty, and species-specific models did not always exist. Therefore, we advocate for further improving tree volume reconstructions with QSMs, especially for fine branches, instead of collecting more ground-truth data to calibrate VEF and allometric models. Promising developments such as improved co-registration and smarter filtering approaches are ongoing to further constrain volumetric errors in TLS-derived estimates. 相似文献
116.
Lin Lin Raffaella Capozzoli Alexia Ferrand Miro Plum Andrea Vettiger Marek Basler 《The EMBO journal》2022,41(13)
Bacteria require a number of systems, including the type VI secretion system (T6SS), for interbacterial competition and pathogenesis. The T6SS is a large nanomachine that can deliver toxins directly across membranes of proximal target cells. Since major reassembly of T6SS is necessary after each secretion event, accurate timing and localization of T6SS assembly can lower the cost of protein translocation. Although critically important, mechanisms underlying spatiotemporal regulation of T6SS assembly remain poorly understood. Here, we used super‐resolution live‐cell imaging to show that while Acinetobacter and Burkholderia thailandensis can assemble T6SS at any site, a significant subset of T6SS assemblies localizes precisely to the site of contact between neighboring bacteria. We identified a class of diverse, previously uncharacterized, periplasmic proteins required for this dynamic localization of T6SS to cell–cell contact (TslA). This precise localization is also dependent on the outer membrane porin OmpA. Our analysis links transmembrane communication to accurate timing and localization of T6SS assembly as well as uncovers a pathway allowing bacterial cells to respond to cell–cell contact during interbacterial competition. 相似文献
117.
Anne Marie W. Efsen Anna Schultze Frank A. Post Alexander Panteleev Hansjakob Furrer Robert F. Miller Marcelo H. Losso Javier Toibaro Aliaksandr Skrahin Jose M. Miro Joan A. Caylà Enrico Girardi Mathias Bruyand Niels Obel Daria N. Podlekareva Jens D. Lundgren Amanda Mocroft Ole Kirk TB:HIV study group in EuroCoord 《PloS one》2015,10(12)
Objectives
Rates of TB/HIV coinfection and multi-drug resistant (MDR)-TB are increasing in Eastern Europe (EE). We aimed to study clinical characteristics, factors associated with MDR-TB and predicted activity of empiric anti-TB treatment at time of TB diagnosis among TB/HIV coinfected patients in EE, Western Europe (WE) and Latin America (LA).Design and Methods
Between January 1, 2011, and December 31, 2013, 1413 TB/HIV patients (62 clinics in 19 countries in EE, WE, Southern Europe (SE), and LA) were enrolled.Results
Significant differences were observed between EE (N = 844), WE (N = 152), SE (N = 164), and LA (N = 253) in the proportion of patients with a definite TB diagnosis (47%, 71%, 72% and 40%, p<0.0001), MDR-TB (40%, 5%, 3% and 15%, p<0.0001), and use of combination antiretroviral therapy (cART) (17%, 40%, 44% and 35%, p<0.0001). Injecting drug use (adjusted OR (aOR) = 2.03 (95% CI 1.00–4.09), prior anti-TB treatment (3.42 (1.88–6.22)), and living in EE (7.19 (3.28–15.78)) were associated with MDR-TB. Among 585 patients with drug susceptibility test (DST) results, the empiric (i.e. without knowledge of the DST results) anti-TB treatment included ≥3 active drugs in 66% of participants in EE compared with 90–96% in other regions (p<0.0001).Conclusions
In EE, TB/HIV patients were less likely to receive a definite TB diagnosis, more likely to house MDR-TB and commonly received empiric anti-TB treatment with reduced activity. Improved management of TB/HIV patients in EE requires better access to TB diagnostics including DSTs, empiric anti-TB therapy directed at both susceptible and MDR-TB, and more widespread use of cART. 相似文献118.
CHOLINESTERASE ACTIVITY OF NODAL AND INTERNODAL REGIONS OF MYELINATED NERVE FIBERS OF FROG 总被引:1,自引:0,他引:1
The distribution of cholinesterase (Ch-esterase) in isolated myelinated fibers of the frog has been investigated. Quantitative microgasometric measurements have confirmed the previous histochemical observations. Both approaches indicate that in frog nerve fibers acetylcholinesterase (ACh-esterase) is the only or the predominant enzyme when selective inhibitors and different substrates are used: acetylcholine (ACh), butyrylcholine, and acetyl-B-methylcholine (Mecholyl). By means of the microgasometric technique, a significant difference in ACh-esterase activity between axons isolated from ventral (37.2 ± 1.7 µmole x 10-5 ACh/mm2/hr) and dorsal roots (2.0 ± 0.9 µmole x 10-5 ACh/mm2/hr) was found. In the region of the node of Ranvier the enzyme activity (50.4 ± 4.4 µmole x 10-5 ACh/mm2/hr) appears to be considerably higher than in the internodal area (36.6 ± 2.1 µmole x 10-5 ACh/mm2/hr). The findings are discussed in relation to the theory of saltatory conduction and the ACh system. 相似文献
119.
120.