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A high density polyethylene geomembrane (GMB) stabilized with hindered amine (light) stabilizers (HALS or HAS) is immersed in four chlorinated water solutions with a simulated free chlorine concentration range of 0.5–5 ppm at five different temperatures (25, 40, 65, 75, and 85 °C) for 70 months. Standard and high pressure oxidative induction time (OIT) tests are performed to monitor antioxidants depletion while melt flow index, tensile, and stress crack resistance (SCR) tests are conducted to monitor degradation in physical and mechanical properties. Degradation in the GMB properties occurred shortly after immersion in chlorinated water at all temperatures except at 25 °C. Increasing the free chlorine concentration resulted in faster degradation of the tensile properties and SCR. The predicted time to nominal failure based on SCR ranges between 25 years at 40 °C and 5 years at 85 °C in chlorinated water (with 0.5 ppm free chlorine). A comparison between the degradation in SCR of this GMB and a GMB with a different resin and without HALS shows significant difference in their performance in chlorinated water but not in other incubation media. 相似文献
3.
Muntasir Hashim Farnoosh Farhad David Smyth‐Boyle Robert Akid Xiang Zhang Philip J. Withers 《工业材料与腐蚀》2019,70(11):2009-2019
The environmental performance of 316L grade stainless steel, in the form of tensile specimens containing a single corrosion pit with various aspect ratios, under cyclic loading in aerated chloride solutions is investigated in this study. Results from environmental tests were compared and contrasted with those obtained using finite element analysis (FEA). Fractography of the failed specimens obtained from experiments revealed that fatigue crack initiation took place at the base of the shallow pit. The crack initiation shifted towards the shoulder and the mouth of the pit for pits of increasing depth. This process is well predicted by FEA, as the strain contour maps show that strain is the highest around the centric strip of the pit. However, for shallow pits, local strain is uniformly distributed around that strip but begins to concentrate more towards the shoulder and the mouth region for increasingly deep pits. 相似文献
4.
ULK1 (unc-51 like autophagy activating kinase 1), a mammalian serine/threonine kinase, is a key component of
autophagy initiation complex and helps to induce all types of autophagy. Canonical autophagy is a process in which,
through the interactions of a series of autophagy-related proteins, damaged organelles or misfolded proteins are
engulfed by autophagosomes and then merged with lysosomes to be degraded. Thus, canonical autophagy is an
important constituent part of the cellular “quality control.” Besides, accumulating evidence indicates that ULK1 exerts
autophagy-independent effects in a cell-specific manner. For example, ULK1 facilitates neurite elongation through the
regulation of endoplasmic reticulum (ER)–Golgi trafficking in neurons, stimulates phosphopentose pathway to help
NADPH (nicotinamide adenine dinucleotide phosphate hydrogen) production, and acts as a duplex regulator in type
I IFN (type I interferon) induced innate immune response. Considering the importance and diversity of ULK1 in
various biological processes, this review aims to present a comprehensive overview of autophagy and non-autophagy
related functions of ULK1 in a variety of human physiological, pathological, and disease processes. 相似文献
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6.
《International Journal of Hydrogen Energy》2020,45(8):5465-5473
Reliable sealing is necessary for the stable operation of proton exchange membrane fuel cell (PEMFC). In practical application, various materials have been tried in PEMFC sealing. However, the mechanical properties of these sealing materials, which play a key role in the sealing stability, have not been fully understood in PEMFC environment, especially after long-term operation. In this paper, according to the operating environment of PEMFC, sealing material experiments are carried out to explore the differences in mechanical behaviors of sealing materials, including silicone rubber (SR), fluororubber (FR), nitrile rubber (NBR) and ethylene-propylene-diene-terpolymer rubber (EPDM) and the variation of mechanical properties of these sealing materials is predicted as time goes on. The results indicate that compression rate has a great influence on sealing contact stress. SR and EPDM, with the variation of 0.15 MPa and 0.45 MPa in stress, show the best and worst mechanical stability at different compression rates, respectively. In terms of temperature, it is found that SR can adapt to different operating temperature of PEMFC and only 18% variation is found from 20 °C to 100 °C. Finally, based on Time-Temperature Superposition (TTS), high temperature experiments are conducted to predict long-term relaxation stress under PEMFC working condition. The analysis results are beneficial for choosing suitable sealing material, and it can also be applied to predict sealing ability in PEMFC. 相似文献
7.
《International Journal of Hydrogen Energy》2020,45(15):9128-9136
Under the tensile loading, the damage of metals in the corrosive medium is the most destructive and harmful. In this study, the stress corrosion cracking behavior of H-charged high-strength steel in 3.5 wt% NaCl solution after electropulsing treatment was investigated. The experimental results from elongation, yield strength, fracture morphology, and polarization curves all demonstrate the positive effect of the pulsed processing, as it reduced the susceptibility of steel to stress corrosion cracking by removing hydrogen by electropulsing. The reduction in hydrogen content of the pulsed high–strength steels was attributed to electromigration and increased system free energy, which drove the hydrogen atoms in the steel to de–trap and reduced the susceptibility to stress corrosion cracking. 相似文献
8.
《Ceramics International》2020,46(3):2915-2922
The growth of thermally grown oxide (TGO) is a significant factor affecting the failure mechanism of thermal barrier coatings (TBCs) during cyclic high temperature service. In this work, a complicated finite element model with two semicircles reflecting the undulation of TGO interfaces was proposed, and four representative shapes of TGO interfaces were selected. There are mainly two methods to simulate TGO growth under high temperature, and each method was achieved by implementation of user subroutines in finite element method. A total of 100 thermal cycle loads were applied to the TBCs continuously. The stress evolution in the layers of Top Ceramic Coating (TC) and Bond Coating (BC) at the end of each thermal cycle load was obtained, the influence of TGO growth on stress evolution was analyzed, the differences between two methods of TGO growth were discussed. The results show that under TGO growth simulated by the first method, the stress distribution in the y direction does not change in both TC and BC layer, and the maximum stress decreases a lot in TC layer but nearly remains the same in BC. When the growth of TGO was simulated by the second method, stress evolution is complex and undergoes up to five stages with a small undulation or convex of TGO interfaces. Stress evolution in BC layer remains as the same as in the first method. Moreover, the maximum stress increases continually in BC layer. The comparison of these two simulation method would help to study the failure of TBCs caused by TGO growth. 相似文献
9.
《Ceramics International》2020,46(4):4857-4863
Assessment of mechanical properties of glass/metal joints is a challenging process, especially when the application relevant conditions of the joints have to be considered in the test design. In this study, a finite element method (FEM) is implemented to analyze a torsional shear strength test designed for glass-ceramic/steel joints aiming towards solid oxide fuel/electrolysis cells application. Deviations from axial symmetry of the square flanges (ends) of respective hourglass-shaped specimens and also supporting and loading sockets of the test set-up are included in the model to simulate conditions close to reality. Undesirable tensile stress and also shear stress concentration appear at the outer edge of glass-ceramic layers, which are less for the hollow-full specimen. The simulation results show that for a specimen with either 9 mm thick square- or 6 mm thick triangular-flanges, locally enhanced tensile stresses almost disappear, resulting in a symmetric shear stress distribution. The difference between the analytically derived nominal shear strength and the real critical shear stress derived via simulation reduces with decreasing the fracture torque. 相似文献
10.
针对采煤机截割机构截割作业过程中作用在截齿上的截割阻力和冲击较大,导致截齿磨损严重、使用寿命短、经济性差的问题,以应变传感器为基础提出了一种新型的截齿受力监控系统,对截割作业过程中截齿的受力进行实时监控。应用结果表明,该监控系统能够精确对截齿受力进行监控,并对截齿的磨损状态和失效状态进行有效判断,及时对其进行调整维护,可以提升截齿截割过程中的截割效率,增加截齿的使用寿命。 相似文献