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101.
A new two-step extraction procedure is proposed for separation and preconcentration of gold nanoparticles (Au-NPs) from aqueous samples. First, Au-NPs are loaded onto a reversed phase C-18 (RP-C18) column, and then ligand-assisted extraction into chloroform is performed. 1-Dodecanethiol (1-DDT, 5 mM) was used as selective ligand for quantitative extraction under ultrasonic condition. Parameters of the extraction procedure, such as sample volume, organic solvent, concentration and nature of the ligand, ultrasonication time, pH of the sample, and different coating as well as sizes of Au-NPs were investigated in regard to the extraction efficiency of Au-NPs. The optimized procedure allows separation and preconcentration of the Au-NPs with an enrichment factor of up to 250 assuring no changes in size and/or shape of the NPs. This was proved by investigation of the particles by UV-vis spectrometry and transmission electron microscopy (TEM). Furthermore, the presence of potentially interfering other metal nanoparticles (M-NPs) and dissolved organic matter (DOM) was studied. Observed minor recoveries of Au-NPs in DOM model solutions were overcome by hydrogen peroxide pretreatment up to a DOM concentration of about 4 mg/L. Feasibility of the proposed method was proved by application of the optimized procedure to 5 real water samples. Recoveries of Au-NPs in the real waters spiked in a concentration range from 0.15 to 5100 μg/L obtained by this method varied from 68.4% to 99.4%. Consequently, the proposed approach has great potential for the analysis of M-NPs in environmental waters. 相似文献
102.
Kerstin Taeschner Hagen BartzschPeter Frach Eberhard Schultheiss 《Thin solid films》2012,520(12):4150-4154
The magnetron-plasma-enhanced chemical vapor deposition (magPECVD) provides silicon-organic thin films for optical, electrically insulating or diffusion barrier coating applications. With process pressures of ≤ 1 Pa this technology is well adapted to the sputtering process of optical interference coatings and also facilitates an inline-process implementation. This paper describes the deposition process for scratch resistant coatings on polycarbonate (PC) and allyl diglycol carbonate substrates. Based on the optical, chemical and mechanical characterization of single magPECVD thin films of varied chemical composition, several types of layer stacks (e.g. of gradient or alternating hardness distribution) were deposited with varied total thickness on PC substrates. Abrasion test results indicate two main effects: the resistance against scratches of high load abrasion (50 N) mainly depends on the total coating thickness. The durability against scratches of low load abrasion (5 N) shows a clear advantage for the multilayer design in contrast to homogeneous single layers even of higher thickness. Finally a 5-layer antireflective system was reactively sputtered onto the magPECVD coating and successfully passed adhesion and environmental tests. 相似文献
103.
Annette Kluge Jürgen Sauer Kerstin Schüler Dina Burkolter 《Theoretical Issues in Ergonomics Science》2013,14(6):489-509
Although simulators have been widely used as training environments in different industries (e.g. oil and nuclear power), there is little rigorous empirical work evaluating the effectiveness of the training methods employed. This article examines the use of simulator training in process control environments. The results of an exploratory field study are reported and the current practices of simulator training are described. The study revealed that simulator training varied considerably across organisations, often with little theoretical or empirical work to guide training design. To evaluate the utility and effectiveness of different methods of simulator training in process control environments, the article also presents a literature review of the research on laboratory- and field-based training. Several training methods are identified as having particular potential for temporal and adaptive transfer and are to be empirically tested in future studies. 相似文献
104.
Jason P. Hadorn Rupalee P. Mulay Kerstin Hantzsche Sangbong Yi Jan Bohlen Dietmar Letzig Sean R. Agnew 《Metallurgical and Materials Transactions A》2013,44(3):1566-1576
The purpose of the present study is to elucidate the cause of a texture transition observed in hot-rolled Mg-Ce alloys, with increasing Ce content. More dilute compositions show a predominance of basal 〈a〉 dislocations, while the more concentrated alloys are shown to contain significant populations of 〈c+a〉 and non-basal 〈a〉 dislocations in the as-rolled and the recovery-annealed conditions. Like Mg-Nd, the grain size in Mg-Ce decreases with increasing Ce. Unlike Mg-Nd, the second-phase particles observed are of the equilibrium phase, and the equilibrium solid solubility at the hot working temperature corresponds to the composition above which weak textures form. The significances of both non-basal slip and Zener pinning as contributors to texture randomization are discussed. 相似文献
105.
Kerstin Schüler Bastian Philippi Martin Weinmann Vera M. Marx Horst Vehoff 《Acta Materialia》2013,61(11):3945-3955
The mechanical properties of nanocrystalline and ultrafine-grained metals strongly depend on grain size, grain boundary segregation, texture and internal stresses. In this paper a thorough systematic analysis is given on the influence of different pulsed electrodeposition processing parameters and grain refiners on the grain size, texture and segregation of Ni and thus on internal stresses. The grain refiner content of the electrolyte, mainly the saccharin content, and the pulse parameters on- and off-time as well as the pulse current density were varied systematically. The combination of different methods of stress and texture analysis allows, among other things, a careful discussion of the influence of saccharin on stress and texture development. Massive tensile specimens were produced with different grain sizes and deformed in incremental load tests. These tests clearly demonstrate the strong effect of the production process on the deformation behavior under constant load. 相似文献
106.
Tikole S Jaravine V Rogov VV Rozenknop A Schmöe K Löhr F Dötsch V Güntert P 《Chembiochem : a European journal of chemical biology》2012,13(7):964-967
Faster than death: NMR techniques that make use of nonlinear sampling and hyperdimensional processing enable the recording of complete NMR data sets for the automated assignment of the backbone and side-chain resonances of short-lived protein samples of cell lysates. 相似文献
107.
Effects of pelvic suspension of beef carcasses on quality and physical traits of five muscles from four gender-age groups 总被引:1,自引:0,他引:1
Pelvic and Achilles suspension methods for beef carcasses were compared for four gender-age groups (24 month bulls, 34 month bulls, heifers, and cows) and five muscles [M. longissimus dorsi (LD), M. semimembranosus (SM), M. adductor (AD), M. psoas major (PM), and M. gluteus medius (GM)]. Pelvic suspension increased muscle and sarcomere lengths in the SM, LD, GM, and AD muscles. The following effects were significant (p < 0.05). Peak force was reduced by pelvic suspension in the LD and GM of bulls-24 and bulls-34, but not heifers and cows. Furthermore, peak forces decreased for the SM after pelvic suspension in bulls-24, bulls-34, and heifers. For the AD, the only decrease in peak force was for bulls-34. Water-holding capacity increased and purge in vacuum bags decreased for pelvic suspension of all muscles except the PM. Although the effects of pelvic suspension varied somewhat between gender-age groups and muscles, this method of hanging carcasses merits industrial consideration because it improves muscle yields, tenderness, and reduces variation within muscles. 相似文献
108.
Thomas CS Svennersten-Sjaunja K Bhosrekar MR Bruckmaier RM 《The Journal of dairy research》2004,71(2):162-168
The internal arrangement of the mammary gland cavity system, cisternal and alveolar milk fractions and the characteristics of milk ejection were investigated in buffaloes. Twenty-four Murrah buffaloes in three different stages of lactation and of two age groups were used. Continuous ultrasound cross-sections during milk ejection induced by exogenous oxytocin were performed to record the latency period of milk ejection. Buffaloes had small cisterns and the cavity area in the teat and gland regions were not significantly different (P > 0.05). The animals had long teat canals (3.1 +/- 0.1 cm), longer in the hind than fore quarters. Cisternal milk yield was low (0.17 +/- 0.01 kg) and cisternal fraction was only 4.9 +/- 0.1% of the total milk. The cisternal area (cm2) was 69.6 +/- 4.6, 51.61 +/- 4.8 and 26.01 +/- 4.8 while the cisternal yield (kg) was 0.32 +/- 0.05, 0.18 +/- 0.05 and 0.05 +/- 0.05 in early, mid and late lactation, respectively. A close correlation (r = 0.87, P < 0.05) existed between the ultrasound cisternal area and cisternal milk yield. The latency period of induced milk ejection was similar to that reported for cows (25 +/- 1 s) and was negatively correlated with milk yield (r = -0.75, P < 0.05). Milk ejection occurred shortly after elevated oxytocin concentrations were present. Delayed milk ejection reported earlier in this species must therefore be due to the absence of cisternal milk and delayed oxytocin release. An increase in teat length and circumference at milk ejection was also evident in the ultrasound cross sections. 相似文献
109.
Effect of low-voltage electrical stimulation after dressing on color stability and water holding capacity of bovine longissimus muscle 总被引:2,自引:0,他引:2
The effect of low voltage electrical stimulation after dressing (ES) on color stability and water holding capacity (WHC) of beef was investigated. Nine Swedish red cattle were slaughtered and the left side was electrically stimulated (80 V, 35 s) approximately 30 min after stunning, whereas the other side was not treated and used as control. Color and its stability, WHC, and protein solubility were evaluated on longissimus lumborum muscles from the two sides. ES produced a brighter red color at 24h mainly by increasing the oxygenation capacity of myoglobin (P<0.01), which was attenuated by postmortem aging. ES did not affect WHC, protein solubility and color stability (P>0.05). Therefore, this technology could accelerate meat tenderization without any negative effect on commercial attributes, such as color or drip of bovine longissimus muscle. 相似文献