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排序方式: 共有58条查询结果,搜索用时 15 毫秒
11.
Ilona Jurek Aleksandra Szuplewska Michał Chudy Kamil Wojciechowski 《Journal of surfactants and detergents》2022,25(2):185-192
The main goal of the study was to compare the effect of aqueous extracts of oat (Avena sativa L.), horse chestnut (Aesculus hippocastanum L.), quinoa (Chenopodium quinoa Willd.), soapwort (Saponaria officinalis L.), cowherb (Vaccaria hispanica [P. Mill.] Rauschert) and soy (Glycine max L.) on model lipid monolayers mimicking the lipid membrane of keratinocytes and intercellular lipids of stratum corneum, and on human skin-related cell lines. Two lipid monolayers, consisting of a dipalmitoylphosphatidylcholine (DPPC) and cholesterol mixture in a molar ratio of 7:3 and Ceramide VI, stearic acid and cholesterol in a molar ratio of 1:1:0.7, and two cell lines (human keratinocyte HaCaT and human skin malignant melanoma A375) were employed. None of the extracts reduced surface pressure below the level achieved for bare monolayers. The strength of the effect on the lipid monolayers (horse chestnut > cowherb > soapwort > soy) points to the existence of some specific interactions responsible for the observed affinity of biosurfactants from the extracts to the lipids in the monolayers. The cytotoxicity tests performed with two model skin cell lines showed that all six plants extracts significantly reduced the cells' viability in a concentration-dependent way. The model lipid monolayers were not solubilized by the investigated surface-active extracts. The latter thus proved interesting candidates for application in mild cleansing cosmetic formulations. Penetration of the monolayers by surface-active components of some extracts, especially horse chestnut, cowherb and soapwort, opens new possibilities for topical delivery of active components. 相似文献
12.
Rajwa B Bernas T Acker H Dobrucki J Robinson JP 《Microscopy research and technique》2007,70(10):869-879
Autofluorescence (AF) originating from the cytoplasmic region of mammalian cells has been thoroughly investigated; however, AF from plasma membranes of viable intact cells is less well known, and has been mentioned only in a few older publications. Herein, we report results describing single- and two-photon spectral properties of a strong yellowish-green AF confined to the plasma-membrane region of transformed human hepatocytes (HepG2) grown in vitro as small three-dimensional aggregates or as monolayers. The excitation-emission characteristics of the membrane AF indicate that it may originate from a flavin derivative. Furthermore, the AF was closely associated with the plasma membranes of HepG2 cells, and its presence and intensity were dependent on cell metabolic state, membrane integrity and presence of reducing agents. This AF could be detected both in live intact cells and in formaldehyde-fixed cells. 相似文献
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Frank Neven Martin Otto Jurek Tyszkiewicz Jan Van den Bussche 《Information and Computation》2001,168(2):156
We study the query language BQL: the extension of the relational algebra with for-loops. We also study FO(FOR): the extension of first-order logic with a for-loop variant of the partial fixpoint operator. In contrast to the known situation with query languages, which include while-loops instead of for-loops, BQL and FO(FOR) are not equivalent. Among the topics we investigate are: the precise relationship between BQL and FO(FOR); inflationary versus noninflationary iteration; the relationship with logics that have the ability to count; and nested versus unnested loops. 相似文献
15.
Monika Lejman Izabela Dziatkiewicz Mateusz Jurek 《International journal of molecular sciences》2022,23(4)
Although the outcome has improved over the past decades, due to improved supportive care, a better understanding of risk factors, and intensified chemotherapy, pediatric acute myeloid leukemia remains a life-threatening disease, and overall survival (OS) remains near 70%. According to French-American-British (FAB) classification, AML is divided into eight subtypes (M0–M7), and each is characterized by a different pathogenesis and response to treatment. However, the curability of AML is due to the intensification of standard chemotherapy, more precise risk classification, improvements in supportive care, and the use of minimal residual disease to monitor response to therapy. The treatment of childhood AML continues to be based primarily on intensive, conventional chemotherapy. Therefore, it is essential to identify new, more precise molecules that are targeted to the specific abnormalities of each leukemia subtype. Here, we review abnormalities that are potential therapeutic targets for the treatment of AML in the pediatric population. 相似文献
16.
Li G Baker SP Qiang Y Grabowski JG McCarthy ML 《Accident; analysis and prevention》2005,37(1):179-184
The Federal Aviation Administration conducts background checking for driving-while-intoxicated (DWI) convictions on all pilots. This study examined the association between DWI history and crash risk in a cohort of 335,672 general aviation pilots. These pilots were followed up from 1994 to 2000 through the aviation crash surveillance system of the National Transportation Safety Board. At baseline, 3.4% of the pilots had a DWI history. DWI history was associated with a 43% increased risk of crash involvement (adjusted relative risk: 1.43; 95% confidence interval: 1.15-1.77). The population-attributable risk fraction for DWI history was estimated as 1.4%. In addition to DWI history, male gender, older age, and inexperience were associated with significantly increased risk of crash involvement. The results of this study support DWI history as a valid risk marker for general aviation pilots. The safety benefit of background checking for DWI history needs to be further evaluated. 相似文献
17.
Titanium was powder siliconized and gas nitrided, in order to improve its cyclic-oxidation resistance. Siliconizing was performed in a pure-silicon powder at temperatures in the range of 800–1100° C for 3–48 h. Gas nitriding was carried out in pure N2 at 1100° C/12 h. Cyclic-oxidation experiments with the siliconized and nitrided samples were conducted in air at 850 and 950° C for up to 560 h. It was found that the siliconized layers grew according to the parabolic law with the activation energy for siliconizing ES being 47.2 kJ mol–1. Powder siliconizing at 900–1100° C/3 h produced multi-phase layers, in which Ti5Si3 silicide predominated The siliconizing temperature of 800° C/3 h appeared to be insufficient, because it led to a non-uniform surface layer with a slight protective effect. The nitrided layers were composed of titanium nitride TiN and -Ti(N) intestitial solid solution. Measurement of the oxidation kinetics revealed that the titanium siliconized at 900–1100° C/3 h oxidized much more slowly than pure Ti, Ti–6Al–4V alloy and nitrided titanium. Microstructural investigation revealed the complex sub-structure of the scales on the siliconized samples which was composed of rutile+silica, rutile and nitrogen-rich sub-layers. The mechanism of high-temperature cyclic oxidation of the siliconized and nitrided titanium is discussed. 相似文献
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19.
Surface protection of titanium by Ti5Si3 silicide layer prepared by combination of vapour phase siliconizing and heat treatment 总被引:1,自引:0,他引:1
D. Vojtch P. Novk P. Mach
M. Moranikov K. Jurek 《Journal of Alloys and Compounds》2008,464(1-2):179-184
In this work we proposed a new method for preparation of protective Ti5Si3 silicide layer. The proposed method consisted of two steps: (1) silicon electron beam evaporation and (2) heat treatment. The silicide-modified titanium was subjected to structural examination, hardness profiling and isothermal oxidation tests. The investigations revealed that the proposed surface treatment produces a layer with a thickness of 1–2 μm and hardness of about 1500 HV. The isothermal oxidation tests showed that the layer is highly resistant to oxidation in air even at 900 °C. Its oxidation rate was comparable or even lower than that of some high-temperature γ-TiAl intermetallics oxidized under similar conditions. The oxidation mechanism was discussed in terms of the internal structure and chemical composition of the scales. It was demonstrated that the silicide layer could serve as excellent protection of titanium, Ti-based alloys and intermetallics against the high-temperature oxidation and wear. 相似文献
20.
RW Fuller JH Cardellina J Jurek PJ Scheuer B Alvarado-Lindner M McGuire GN Gray JR Steiner J Clardy E Menez 《Canadian Metallurgical Quarterly》1994,37(25):4407-4411
Ten halogenated monoterpenes (2-6 and 8-12) related to the novel antitumor compound halomon (1) or to the carbocyclic analog 7 have been isolated from different geographic collections of the red alga, Portieria hornemannii. Structures were assigned to the basis of spectral analyses (primarily NMR and MS). The absolute configuration of isohalomon (2) was further established by X-ray crystallography. The compounds were comparatively evaluated alongside 1 and 7 in the U.S. National Cancer Institute's in vitro human tumor cell line screening panel. The results provide some interesting initial insights into the structure/activity relationships in this series. 相似文献