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排序方式: 共有854条查询结果,搜索用时 234 毫秒
81.
Suyeon Kim Carla Silva Andrea Zille Carmen Lopez Dmitry V Evtuguin Artur Cavaco‐Paulo 《Polymer International》2009,58(8):863-868
BACKGROUND: The ‘double function’ of laccase, from the ascomycete Myceliophthora, to depolymerise/polymerise lignin was studied in this work. A lignosulfonate (LS) compound was oxidised by enzymatic action and several techniques were applied to measure the polymeric changes obtained. This study was focused on the attachment level of the oxidised LS at the flax surface. RESULTS: Modified solutions were studied in terms of surface charge. Zeta potential values obtained showed an increase of polymerisation after several days of incubation. The change in molecular weight after LS polymerisation was detected using gel permeation chromatography. An increase of 1700 Da was achieved. Fourier transform infrared and UV‐visible spectroscopy techniques were applied and the results showed an increase of the degree of polymerisation. The colour strength of flax fabrics incubated with oxidised LS solutions was also measured and an increase of K/S (K, absorption coefficient; S, scattering coefficient) after enzymatic oxidation was observed. CONCLUSION: The oxidised lignin products obtained show good potential for use in natural surface modification of textile materials containing flavonoids. These findings have important practical implications for lignocellulosic fibre coloration, where new polymers can replace harsh chemicals in the textile industry. Copyright © 2009 Society of Chemical Industry 相似文献
82.
Study of self-stratifying compositions 总被引:2,自引:0,他引:2
Helena Kuczyńska Ewa Langer Elżbieta Kamińska-Tarnawska Dmitry A. Kulikov Eugene A. Indeikin 《Journal of Coatings Technology and Research》2009,6(3):345-352
Paint applied as a single layer, and its spontaneous separation to form a primer and a top coat, is one of the newest concepts
of the effective and economical application of two layers in one step. The influence of the molecular weight of epoxy oligomer
and acrylic polymer and their ratio on self-stratification was investigated. The degree of stratification depending on molecular
weight and their mutual ratio was determined using ATR-FTIR spectroscopy, differential scanning calorimetry, microscopy techniques,
adhesion tests, and surface tension measurements. Phase separation and self-stratification of two-component homogenous mixtures
were followed using FTIR technique and surface tension measurements. As a result of these investigations, optimal oligomeric/polymeric
composition was selected. The obtained coating system showed good mechanical properties, gloss, and interlayer adhesion. 相似文献
83.
The effect of selected parameters of formation on properties of alginate/Ca2+/oligochitosan capsules
Artur Bartkowiak Sawomir Lisiecki Gorka Orive Jose Luis Pedraz 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2006,81(4):511-518
Optimization of the technological parameters affecting the mechanical properties and permeability of capsules is essential to produce capsules with improved properties for cell immobilization. In the present paper, the effect of different parameters on the technological properties of alginate/Ca2+/oligochitosan capsules has been investigated. The correct adjustment of the alginate concentration in the polymer matrix and the oligochitosan molar mass, concentration and coating time, have been found to be key parameters in obtaining porous and mechanically stable alginate/Ca2+/oligochitosan capsules. Results showed that an increase in the coating time and concentration of the alginate generated more stable capsules with a reduced membrane cut‐off. Furthermore, we have established some correlations between capsule properties and the effectiveness of chitosan binding within the capsule's membrane. Data addressed herein could be a valid tool to fabricate optimized alginate/Ca2+/oligochitosan capsules with a potential for use in cell immobilization technology. Copyright © 2006 Society of Chemical Industry 相似文献
84.
A new measurement system and a mapping technique for immunity or susceptibility testing are discussed. The most unique point of the system is that the electromagnetic (EM) fields are of slowly rotating polarization controlled electronically. In this paper, methods for generating slowly rotating fields are discussed. The direction of field polarization can be varied continuously and in a short time. By combining the method with a turntable, for example, the immunity-or susceptibility-characteristic maps can be obtained easily. This visualization technique is useful to detect the immunity or susceptibility attributes at a glance and thus may make the development of products with high immunity easy 相似文献
85.
M Cholewa A Cwetsch L Kubik G Kamiński A Skrobowski 《Canadian Metallurgical Quarterly》1997,3(14):65-67
We evaluated effects of perindopril (Prestarium-SERVIER) in the treatment of the primary hypertension in 41 patients (mean age 41.6) in the I or II degrees WHO using 24 ambulatory blood pressure measurement and echocardiography. Investigation were performed before and after 3 and 6 months of the treatment. Initially 4 mg of perindopril was given and individually was increased after 3 months to 8 mg according to 24 ambulatory blood pressure measurement results. We obtained significant decrease of blood pressure in 3 (134.6/86.6 mm Hg) and in 6 (135/88, 9 mm Hg) months of treatment in comparison to baseline values (141.8/91.1 mm Hg), decrease of left ventricular mass to 244.4 g in 3 and 248.8 g after 6 months (baseline 258.5 g), as well as index of left ventricular mass, wall thickness and left ventricular end diastolic volume. There was no significant differences in: ejection, heart rate, left ventricular inflow on the successive investigations. Good effect of perindopril we observed in 31 patients (75.6%) after 6 months of treatment. We did not observe any serious side effects of perindopril. CONCLUSION: Perindopril in treatment hypertension effectively reduces the level of blood pressure (systolic, diastolic and mean) without any effect on heart rate. Prestarium reduces left ventricular mass, intraseptal wall thickness and left ventricular end diastolic volume. There is no influence on inflow to the left ventricle as well as on ejection fraction. 相似文献
86.
87.
Sabine Heublein Doris Mayr Klaus Friese Maria Cristina Jarrin-Franco Miriam Lenhard Artur Mayerhofer Udo Jeschke 《International journal of molecular sciences》2014,15(9):15161-15172
Ovarian granulosa cell tumors (GCTs) are thought to arise from cells of the ovarian follicle and comprise a rare entity of ovarian masses. We recently identified the G-protein-coupled estrogen receptor (GPER/GPR30) to be present in granulosa cells, to be regulated by gonadotropins in epithelial ovarian cancer and to be differentially expressed throughout folliculogenesis. Thus, supposing a possible role of GPER in GCTs, this study aimed to analyze GPER in GCTs. GPER immunoreactivity in GCTs (n = 26; n (primary diagnosis) = 15, n (recurrence) = 11) was studied and correlated with the main clinicopathological variables. Positive GPER staining was identified in 53.8% (14/26) of GCTs and there was no significant relation of GPER with tumor size or lymph node status. Those cases presenting with strong GPER intensity at primary diagnosis showed a significant reduced overall survival (p = 0.002). Due to the fact that GPER is regulated by estrogens, as well as gonadotropins, GPER may also be affected by endocrine therapies applied to GCT patients. Moreover, with our data supposing GPER to be associated with GCT prognosis, GPER might be considered as a possible confounder when assessing the efficacy of hormone-based therapeutic approaches in GCTs. 相似文献
88.
Programmers today face a bewildering array of parallel programming models and tools, making it difficult to choose an appropriate one for each application. An increasingly popular programming model supporting structured parallel programming patterns in a portable and composable manner is the task‐centric programming model. In this study, we compare several popular task‐centric programming frameworks, including Cilk Plus, Threading Building Blocks, and various implementations of OpenMP 3.0. We have analyzed their performance on the Barcelona OpenMP Tasking Suite benchmark suite both on a 48‐core AMD Opteron 6172 server and a 64‐core TILEPro64 embedded many‐core processor. Our results show that the OpenMP offers the highest flexibility for programmers, and this flexibility comes to a cost. Frameworks supporting only a specific and more restrictive model, such as Cilk Plus and Threading Building Blocks, are generally more efficient both in terms of performance and energy consumption. However, Intel's implementation of OpenMP tasks performs the best and closest to the specialized run‐time systems. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
89.
Leveraging the Ambipolar Transport in Polymeric Field‐Effect Transistors via Blending with Liquid‐Phase Exfoliated Graphene 下载免费PDF全文
90.
Artur GUTKOWSKI 《热科学学报(英文版)》2006,(2)
Following the quantitative determination of dust cloud parameters, this study investigated the flame propagation through cornstarch dust clouds in a vertical duct of 780 mm height and 160×160 mm square cross section, and gave particular attention to the effect of turbulence on flame characteristics. The turbulence induced by dust dispersion process was measured using a particle image velocimetry (PIV) system. Upward propagating dust flames were visualized with direct light and shadow photography. The results show that a critical value of the turbulence intensity can be specified below which laminar flame propagation would be established. This transition condition is about 10 cm/s. The measured propagation speed of laminar flames appears to be in the range of 0.45-0.56 m/s, consistent with the measurements reported in the literature. For the present experimental conditions, the flame speed is little sensitive to the variations in dust concentration. Some information on the flame structure was revealed from the shadow records, showing the typical heterogeneous feature of dust combustion process. 相似文献