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41.
A galvanic displacement technique is used to coat silicon scanning force microscopy cantilevers with copper. The copper coating is characterized using X-ray photoelectron spectroscopy, scanning force microscopy, contact angle measurements, scanning electron microscopy and energy-dispersive X-ray spectroscopy. This coating technique results in uniform, reflective and conformal films and hence, no stress-induced bending of the cantilever is observed. To demonstrate the effectiveness of this approach for tribological studies, the coated cantilevers are chemically modified with alkanethiol monolayers in order to functionalize the cantilevers. The effect of changed surface energy are detected with adhesion measurements in water and ethanol. 相似文献
42.
Current Understanding of Structure–Processing–Property Relationships in BaTiO3–Bi(M)O3 Dielectrics 下载免费PDF全文
Michaela A. Beuerlein Nitish Kumar Tedi‐Marie Usher Harlan James Brown‐Shaklee Natthaphon Raengthon Ian M. Reaney David P. Cann Jacob L. Jones Geoff L. Brennecka 《Journal of the American Ceramic Society》2016,99(9):2849-2870
As part of a continued push for high permittivity dielectrics suitable for use at elevated operating temperatures and/or large electric fields, modifications of BaTiO3 with Bi(M)O3, where M represents a net‐trivalent B‐site occupied by one or more species, have received a great deal of recent attention. Materials in this composition family exhibit weakly coupled relaxor behavior that is not only remarkably stable at high temperatures and under large electric fields, but is also quite similar across various identities of M. Moderate levels of Bi content (as much as 50 mol%) appear to be crucial to the stability of the dielectric response. In addition, the presence of significant Bi reduces the processing temperatures required for densification and increases the required oxygen content in processing atmospheres relative to traditional X7R‐type BaTiO3‐based dielectrics. Although detailed understanding of the structure–processing–property relationships in this class of materials is still in its infancy, this article reviews the current state of understanding of the mechanisms underlying the high and stable values of both relative permittivity and resistivity that are characteristic of BaTiO3‐Bi(M)O3 dielectrics as well as the processing challenges and opportunities associated with these materials. 相似文献
43.
Berengere PAPEGAY Michaela STADLER Vincent Nuyens Isabelle SALMON Veronique KRUYS Jean G. BOOGAERTS 《Biocell》2014,38(1):25-32
Ischemia-reperfusion injury is a determinant in liver injury occurring during surgery, ischemic
states and multiple organ failure. The pre-existing nutritional status of the liver, i.e., fasting, might contribute to
the extent of tissue injury. This study investigated whether alanine, an amino acid precursor of glucose, could
protect ex vivo perfused livers of fasting rats from reperfusion injury. The portal vein was cannulated, the liver removed and perfused in a closed ex vivo system. Isolated livers were perfused either with glucose 1 g/L and 10 g/L,
or with equal concentrations of alanine (n = 10 in each group). The experiment consisted of perfusion for 15 min,
ischemia for 60 min, and reoxygenation during 60 min. Enzymes, glucose, lactate and bilirubin were analysed
in perfusate samples. The proportion of glycogen as well as activation of caspase 3 was determined in biopsies.
Alanine at a concentration of 10 g/L attenuated enzymes release in the perfusate during reoxygenation when compared to glucose-treated groups. Lactate level in the perfusate was lowest in alanine groups. Ischemia-reperfusion
and mainly alanine activated apoptosis, specifically in Kupffer and endothelial cells. Alanine presents a protective effect on normothermic ischemia-reperfusion injury of the fasting rat liver when compared to glucose 相似文献
44.
?árka Houdková Olga Bláhová Franti?ek Zahálka Michaela Ka?parová 《Journal of Thermal Spray Technology》2012,21(1):77-85
Elastic-plastic properties, namely, hardness and Young’s modulus, of four HVOF-sprayed hardmetal coatings were measured by
instrumented indentation using Oliver-Pharr method Nanoindenter XP MTS with a continuous stiffness measurement (CSM) module.
The results show that with sufficient number of CSM measurements, one can distinguish between indents made in the hard particles
and indents made in the binder material. This can be accomplished by analyzing the plots of hardness and Young’s modulus versus
load (or versus indentation depth). Further development of the dependence curves enables the load (or indentation depth) to
be set to correspond to the point of transition from a single structure component to the composite material and to determine
the properties of both. Comparison of results of CSM measurement with the results of single indentation measurement at a defined
load reveals a new perspective on the origin of the indentation size effect in hardmetal coatings. The measurements show that
the increase in both the hardness and Young’s modulus with decreasing load is caused mainly by the predominant influence of
hard particles in the coatings. 相似文献
45.
Five early maturing varieties of Prunus avium L. on dwarfing rootstock were forced at Bonn, Germany in spring under transparent plastic cover without additional heating to ripen at a time before field-grown German fruit become available, with better fruit quality than imported sweet cherries; trees grown outside without cover served as control. The cover reduced the incident radiation by up to 54% PAR, UV by up to 22% UV-A and UV-B up to 2% and increased day temperature indoors. Fruit were as firm in the early varieties grown under cover as those in the field and slightly softer than in the late harvesting cultivars. Sugar content was slightly less in four of the five varieties; no differences in acidity and sugar/acid ratio as a taste indicator were found. Fruits were up to 3 mm larger when grown under cover in cvs. ‘Burlat’ and ‘Souvenir’, but no differences were observed in cvs. ‘Earlise’ and ‘Prime Giant’. Fruit of three cultivars, ‘Burlat’, ‘Samba’ and ‘Prime Giant’ can be classified as premium quality with 28 mm–30 mm diameter, when grown under cover. Overall, all cherry fruit were of the market, i.e. consumer- preferred, dark red colouration in line with enhanced anthocyanin contents. In two cultivars, the cover induced healthier fruit. Antioxidative capacity was larger in cv. ‘Samba’, while ascorbic acid (Vitamin C) was increased in cv. ‘Souvenir’; phenols were enhanced in all cultivars and attributed to heat stress. Allergenic protein (Pru av 1) in cherry fruits of both cultivation types were below the detection level at harvest time, indicating that cultivation under cover had no adverse effects on this particular health component.Overall, forcing successfully resulted in 2 weeks earlier ripening, thereby providing the first fresh and healthy (low allergen, high phenolic compounds and high anthocyanin) German cherries of high fruit quality on the market in spring. 相似文献
46.
Michaela Dina Stanescu Simona Gavrilas Roland Ludwig Dietmar Haltrich Vladimir I. Lozinsky 《European Food Research and Technology》2012,234(4):655-662
A new biocatalyst was prepared by the immobilization of a Trametes pubescens laccase, into a wide-pore poly(vinyl alcohol) cryogel. The known enzyme was produced and purified by the previously described
procedure. The resulted laccase (yield 40%) has an activity of 46.4 U mg−1 and 12.51 mg mL−1 protein content. The enzyme was subsequently immobilized in a functionalized macroporous cryogel beads by a covalent immobilization
technique. The time dependence of the immobilization process and the enzyme loading of the carrier material (5.2 mg g−1 cryogel) were determined by measuring the decrease of protein amount in the enzyme solution. In conversion experiments, a
higher stability of the immobilized biocatalyst compared to the free enzyme was evidenced. Steady-state kinetic characterization
of four phenols (catechol, caffeic and chlorogenic acids, and catechin) has been performed with free and immobilized laccase,
the catalytic parameters being determined and compared. The effect of both laccases (free and immobilized) on the phenol content
of retailed apple juice samples, having the same initial composition, was also investigated by working in batch conversion.
The variation in phenolic compound content has been compared with that of an untreated apple juice sample having initially
the same content of phenolic compounds. A number of advantages resulted in using the immobilized laccase for the apple juice
treatment (conservation to some extent of enzyme activity, higher content of phenols preserved, easy separation of the enzyme
from the apple juice, therefore avoiding the possible unhealthy effects due to the remaining protein, etc.). 相似文献
47.
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49.
Stewart R Thom G Levens M Güler-Gane G Holgate R Rudd PM Webster C Jermutus L Lund J 《Protein engineering, design & selection : PEDS》2011,24(9):671-678
Ribosome display was applied to the Fc region of human immunoglobulin G (IgG1) to select for improved binding to human FcγRIIIa, the receptor expressed on human natural killer cells that mediates antibody-dependent cellular cytotoxicity (ADCC). A library of human Fcγ1 variants was generated using error-prone polymerase chain reaction, and subjected to multiple rounds of ribosome display selection against progressively decreasing concentrations of soluble human FcγRIIIa, to enrich for improved binders. Radioimmunoassay and alphascreen analyses of the aglycosylated IgG-Fc output revealed variants with improved binding to FcγRIIIa relative to wild-type IgG-Fc. Subsequent expression in human (HEK-EBNA) cells generated glycosylated IgGs with modified activity in ADCC assays. One particular variant, 125_B01 triggered enhanced ADCC (EC(50) up to four-fold reduced with increased maximal lysis) relative to wild-type antibody, having more equal levels of ADCC for each allotype (V158/F158) of FcγRIIIa. Deconvolution of individual replacements within the variant showed that improved function arose from the Phe243Leu replacement within the CH2 domain, rather than the CH3 domain replacements Thr393Ala or His433Pro. Surprisingly, the oligosaccharide profiles of 125_B01 indicated more oligosaccharide chains lacking fucose, or with bisecting N-acetylglucosamine relative to wild-type IgG1, which correlates with improved function and the replacement Phe243Leu that is a carbohydrate contact residue within the C(H)2 domain. 相似文献
50.
Gebauer D Oliynyk V Salajkova M Sort J Zhou Q Bergström L Salazar-Alvarez G 《Nanoscale》2011,3(9):3563-3566
Nanocellulose hybrids are promising candidates for biodegradable multifunctional materials. Hybrids of nanocrystalline cellulose (NCC) and amorphous calcium carbonate (ACC) nanoparticles were obtained through a facile chemical approach over a wide range of compositions. Controlling the interactions between NCC and ACC results in hard, transparent structures with tunable composition, homogeneity and anisotropy. 相似文献