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61.
PURPOSE: The clinical significance of subretinal bleeding without choroidal neovascularization in pathologic myopia is unclear. Only two reports in the ophthalmic literature have demonstrated the clinical course of subretinal bleeding and have indicated that it might be a precursor of lacquer cracks. In this study, the authors observed the clinical course of subretinal bleeding in highly myopic eyes and studied this condition in relation to new lacquer crack formation. METHODS: The authors examined consecutively and prospectively 22 highly myopic eyes (19 patients) with subretinal bleeding. Indirect ophthalmoscopy and fluorescein fundus angiography were performed in all patients. Indocyanine green (ICG) angiography could be performed in three patients. The follow-up period ranged from 6 to 198 months (mean, 61.3 months). RESULTS: In 17 of 22 eyes, lacquer cracks appeared at the site of previous subretinal bleeding. The period for the formation of new lacquer cracks after the onset of the bleeding ranged from 2 to 6 months (mean, 4.0 months). In one patient, ICG angiography revealed linear hypofluorescence, indicating a ruptured Bruch's membrane at the onset of subretinal bleeding. CONCLUSION: A rupture of Bruch's membrane and choriocapillaris complex results in subretinal bleeding, which is the first process of new lacquer crack formation. Atrophy of the overlying pigment epithelium and further scar formation results in the development of a lacquer crack. 相似文献
62.
Decomposition of Ruthenium Oxides in Lead Borosilicate Glass 总被引:2,自引:0,他引:2
Behaviors of apparent phase changes of Ru-containing oxides in lead borosilicate glass at high temperature have been investigated using X-ray diffraction and transmission electron microscopy in application to thick-film resistors. During firing of thick films containing Ru oxide powder and lead borosilicate glass frits, apparent phase changes of Ru oxides have been found to occur both ways between ruthenium dioxide and lead ruthenate pyrochlore via decomposition of one phase in glass and subsequent formation of the other. The formation of pyrochlore occurs in a lead-rich form, Pb2 (Ru2− x Pb x )O6.5 , whereas the formation of RuO2 is characterized by a platelike morphology instead of initial globular morphology. A general tendency is observed that RuO2 is stable in low-PbO glass compositions and at high temperatures, while Pb2 (Ru2− x Pb x )O6.5 is stable in high-PbO glass compositions and at low temperatures, with the implication that the stability of these phases is dictated by the chemical activity of PbO in the glass melt. 相似文献
63.
The tumor-promoting agent 4β-phorbol-12-myristate-13-acetate (TPA) is shown to be a potent stimulator of fatty acid synthesis
in isolated rat hepatocytes. The maximal effect of TPA is seen at 10−6 M, and the concentration for half-maximal effect is ca. 10−8 M. Stimulation of fatty acid synthesis by TPA is shown not to require the presence of extracellular Ca++. TPA produces a significant increase in lactate and pyruvate accumulation. The possible involvement of protein kinase C in
short-term regulation of fatty acid synthesis in the liver is discussed. 相似文献
64.
Thiobarbituric acid reaction of aldehydes and oxidized lipids in glacial acetic acid 总被引:1,自引:0,他引:1
Thiobarbituric acid (TBA) reaction of several aldehydes and oxidized lipids in glacial acetic acid was performed. All the
samples were freely soluble in the solvent used. Saturated aldehydes produced a stable yellow pigment with an absorption maximum
at 455 nm, a red pigment derived from malonaldehyde at 532 nm, and an orange pigment due to dienals at 495 nm. The absorbance
maximum was 7–9 per μmol for saturated aldehydes, 27.5 per μmol for malonaldehyde and about 2 per μmol for dienals. Autoxidation
of unoxidized lipids increased progressively in glacial acetic acid. When the TBA test was performed under nitrogen, autoxidation
of unoxidized lipids was inhibited completely. While saturated aldehydes produced no yellow pigment under nitrogen, oxidized
lipids produced a considerable amount of stable yellow pigment. The value for absorbance at 455 nm as a function of autoxidation
time paralleled those of peroxide values. The absorbance of most oxidized lipids at 455 nm was higher than at 532 nm. Yellow
pigment formation in the TBA test under nitrogen could not be ascribed to free saturated aldehydes but rather to unspecified
closely related substances. The stable yellow pigment was found to be an excellent indicator of lipid oxidation. 相似文献
65.
Yingxi Zhu Hiroko Ohtani Michael L. Greenfield Marina Ruths Steve Granick 《Tribology Letters》2003,15(2):127-134
The molecular-level function of model and commercial friction modifier additives in lubricants of the type used at the wet clutch interface in automatic transmissions has been studied using a surface forces apparatus (SFA) modified for oscillatory shear. The nanorheological properties of tetradecane with and without a model friction modifier additive (1-hexadecylamine) were examined in the boundary lubrication regime and compared to a fully-formulated automatic transmission fluid (ATF). 1-Hexadecylamine adsorbed as a single layer on the sliding surfaces, reduced the static frictional force and the limiting shear stress, and eliminated the stick–slip transition that exists in pure tetradecane. The ATF, which contains commercial-grade friction modifiers, showed nanorheological properties similar to those observed for tetradecane containing 0.1–0.2 wt% 1-hexadecylamine. 相似文献
66.
Methods for the chemical recycling of polycarbonate (PC) wastes in the forms of bisphenol A (BPA) and cyclic heterocarbonates, such as 1,3‐dithiolan‐2‐one (DTO), 1,3‐dithiane‐2‐one (DTA), and cyclic unsymmetric heterocarbonates, were investigated to prove that PC can be utilized as a phosgene equivalent for industrial purposes. Treatment of PC pellets or waste PC compact discs with 1,2‐ethanedithiol and a catalytic amount of base (e.g., 1.5 mol % NaOH) in dioxane for a short period at 40°C produced DTO and BPA, both in nearly quantitative yields. The reaction could also be carried out in DTO, which saved the use of conventional solvents. Other cyclic heterocarbonates, that is, DTA, 1,3‐oxathiolan‐2‐one, 1,3‐thiazolidine‐2‐one, and N‐methyl‐1,3‐oxazolidine‐2‐one, were prepared in high yields under analogous conditions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2959–2968, 2003 相似文献
67.
A procedure for the preparation of specific molecular species ofd-erythro-lactosylceramide involving deacylation and reacylation of lactosylceramide prepared from bovine brain gangliosides is described.
Lactosylceramide wasN-deacylated by alkaline hydrolysis and the resulting four lysolactosylceramides, which contained d18∶1, d20∶1, d18∶0 and d20∶0
long-chain bases, were simultaneously re-N-acylated with theN-succinimidyl ester of either 16∶0, 18∶0, 20∶0, 24∶0, 20∶1, 22∶1 or 24∶1 fatty acid. The resulting lactosylceramide contained
four molecular species of lactosylceramides, i.e., d18∶1, d20∶1, d18∶0 and d20∶0 long-chain bases coupled with the fatty acid
that was introduced. Lactosylceramides prepared in this manner were separated into four individual molecular species by high-performance
liquid chromatography (HPLC). Each of the purified molecular species of lactosylceramide was quantitated by HPLC after derivatization
with benzoylchloride and was characterized by mass spectrometry. The yields of reacylated lactosylceramide were 38–58% relative
to the starting lactosylceramide; the purity of each of the molecular species of lactosylceramide was greater than 95%.
The glycosphingolipid nomenclature is as recommended by the IUPAC-IUB Commission on Biochemical Nomenclature (1). GalCer,
galactosylceramide, Gal(β1-1)Cer; GlcCer, glucosylceramide, Glc(β1-1)Cer; LacCer, lactosylceramide, Gal(β1-4)GlcCer; GbOse3Cer, globotriaosylceramide, Gal(α1-4)Gal(β1-4)GlcCer; GbOse4Cer, globotetraosylceramide, GalNAc(β1-3)Gal(α1-4)-Gal(β1-4)GlcCer; GgOse3Cer, gangliotriaosylceramide, GalNAc-(β1-4)Gal(β1-4)GlcCer; GgOse4Cer, gangliotetraosylceramide, Gal(β1-3)GalNAc(β1-4)Gal(β1-4)GlcCer; GM3, (NeuAcα2-3)-Galβ1-4GlcCer; GM1, Galβ1-3GalNAcβ1-4(NeuAcα2-3)Galβ1-4-GlcCer.
The molecular species abbreviations suggested by Breimeret al. (2) are used. For example, in the notation d18∶1−18∶0, the d18∶1 represents the long-chain base sphingosine (d-erythro-1,3-dihydroxy-2-amino-trans-4-octadecene) and 18∶0 represents the fatty acid (octadecanoic acid). 相似文献
68.
Iain P. McTaggart Hiroko Akiyama Haruo Tsuruta Bruce C. Ball 《Nutrient Cycling in Agroecosystems》2002,63(2-3):207-217
In Japan, upland soils are an important source of nitrous oxide (N2O) and nitric oxide (NO) gas emissions. This paper reports on an investigation of the effect of soil moisture near saturation on N2O and NO emission rates from four upland soils in Japan of contrasting texture. The aim was to relate these effects to soil physical properties. Intact cores of each soil type were incubated in the laboratory at different moisture tensions after fertilisation with NH4-N, NO3-N or zero N. Emissions of N2O and NO were measured regularly over a 16–20 day period. At the end of the incubation, soil cores were analysed for physical properties. Moisture and N fertiliser significantly affected rates of emissions of both N2O and NO with large differences between the soil types. Nitrous oxide emissions were greatest in the finer-textured soils, whereas NO emissions were greater in the coarser-textured soils. Emissions of N2O increased at higher moisture contents in all soils, but the magnitude of increase was much greater in finer-textured soils. Nitric oxide emissions were only significant in soils fertilised with NH4-N and were negatively correlated with soil moisture. Analysis of soil properties showed that there was a strong relationship between the magnitude of emissions and soil physical properties. The importance of soil wetness to gas emissions was mainly through its influence on soil air-filled porosity, which itself was related to gas diffusivity. From the results of this research, we can now estimate likely effects of soil texture on emissions through the influence of soil type on soil aeration and soil drainage. This is of particular value in modelling N2O and NO emissions from soil moisture status and land use inputs. 相似文献
69.
Imoto Taiji; Yamada Hidenori; Yasukochi Takanori; Yamada Eiichi; Ito Yuji; Ueda Tadashi; Nagatani Hiroko; Miki Takeyoshi; Horiuchi Tadao 《Protein engineering, design & selection : PEDS》1987,1(4):333-338
In the preceding paper in this issue, we described the overproduction of one mutant chicken lysozyme in Escherichia coil.Since this lysozyme contained two amino acid substitutions (Ala31ValandAsn106Ser)in addition to an extra methionine residue at theNH2-terminus the substituted amino acid residues were convertedback to the original ones by means of oligonucleotide-directedsite-specific mutagenesis and in vitro recombination. Thus fourkinds of chicken lysozyme [Met1 Val31Ser106-, Met1Ser106-,Met1 Val31-and Met1 (wild type)] wereexpressed in E. coli. From the results of folding experimentsof the reduced lysozymes by sulfhydryl-disulfide interchangeat pH 8.0 and 38°C, follow ed by the specific activity measurementsof the folded en zymes, the following conclusions can be drawn:(i) an extra methionine residue at the NH2-terminus reducesthe folding rate but does not affect the lysozyme activity ofthe folded enzyme; (ii) the substitution of Asn106 by Ser decreasesthe activity to 58% of that of intact native lysozyme withoutchanging the folding rate; and (iii) the substitution of Ala31Val prohibits the correct folding of lysozyme. Since the wildtype enzyme (Met1-lysozyme) was activated in vitro withoutloss of specific activity, the systems described in this study(mutagenesis, overproduction, purification and folding of inactivemutant lysozymes) may be useful in the study of folding pathways,expression of biological activity and stability of lysozyme. 相似文献
70.
Masabumi Masuko Akihito Suzuki Yu Sagae Maiko Tokoro Kenji Yamamoto 《Tribology International》2006,39(12):1601
Water has been considered as an alternative working fluid for hydraulic power systems in order to minimize the consumption of fossil fuels and mineral oils. In spite of the many advantages to this use of water, difficult technical problems remain. The key technology for establishing a water hydraulic system is tribology, because water has a lack of lubricity, and thus some coating is needed to protect the metal surfaces from corrosion and frictional wear when using water as a lubricant. It has already been demonstrated that some Si-containing materials have good lubricity in a water environment. Recently, it has been shown that diamond-like carbon (DLC) coatings also have good lubricity with water. In order to clarify the mechanism by which such materials are lubricated with water, and to develop surface coatings that have good lubricity with water, the friction characteristic of several coated metals were investigated in this study. Coatings of CrN, CrSiN, and two types of DLC were applied on an SUS630 stainless steel flat disk substrate. Additive-free distilled water was used as a lubricating fluid. The friction characteristics of these coatings at different sliding speeds were evaluated using a tribometer with two contact configurations in which stainless steel balls and a flat ring without coatings were used as mating specimens.In addition, the lubrication characteristics of organic hydro-gels such as alginic acid or its metal salt were studied by immobilizing them on the surface, and their effects on the lubrication with water were discussed. 相似文献