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排序方式: 共有3253条查询结果,搜索用时 15 毫秒
101.
Tae Jo Ko Jung Whan Park Hee Sool Kim Sun Ho Kim 《The International Journal of Advanced Manufacturing Technology》2007,32(7-8):739-746
Once a machining process is finished, an inspection process is carried out to check whether the part is within dimensional
tolerances. A coordinate measuring machine (CMM) is a general metrological device for assessment of dimensions on the shop
floor. It cannot be ignored, however, that CMM measurements require significant resources in operating time and cost, which
has led to many studies into on-machine measurement (OMM) systems. This study aims to develop an OMM system with a noncontacting
laser displacement sensing apparatus and a computer-aided design (CAD) model for ease of operation, improved operating speed,
and free form profiling. The system is composed of two software modules, one for sensor alignment with the machine tool and
the other for measurement based on CAD/CAM (computer-aided machining). Consequently, the system was verified on the shop floor
at a numerical control (NC) machining center. 相似文献
102.
To examine the fracture characteristics of low-heat concrete which is used to prevent the thermal crack caused by hydration heat, static loading test was performed by Determination of the Fracture Energy of Mortar and Concrete by Means of Three-Point Bend Tests on Notched Beam (suggested by RILEM 50-FMC Committee). Fracture energy of Mode I (opening mode) for the Ordinary and Low-Heat Concrete is compared and examined according to experimental variables, such as water-cement ratio, compressive strength and age. Test results show that the deflections at the fracture was decreased as the fracture strength were increased and the reduction of water-cement ratio caused to increase fracture energy in both specimens. The fracture energy of low-heat concrete turned out to be similar to that of ordinary portland concrete as the increases. 相似文献
103.
Hydrothermal fractionation for micro-algae, Schizocytrium sp., was investigated to separate sugars, lipids, and proteins. This fractionation process produced protein-rich solid cake
and liquid hydrolysates, which contained oligomeric sugars and lipids. Oligomeric sugars and lipids were easily separated
by liquid-liquid separation. Sugars in the separated hydrolyzate were determined to be mainly D-glucose and L-galactose. Fractionation
conditions were optimized by response surface methodology (RSM). Optimal conditions were found to be 115.5 °C of reaction
temperature, 46.7 min of reaction time, and 25% (w/w) of solid loading. The model predicted that maximum oligomeric sugar
yield (based on untreated micro-algae weight), which can be recovered by hydrothermal fractionation at the optimum conditions,
was 19.4 wt% (based on the total biomass weight). Experimental results were in agreement with the model prediction of 16.6
wt%. Production of bioethanol using micro-algae-induced glucan and E. coli KO11 was tested with SSF (simultaneous saccharification and fermentation), which resulted in 11.8 g-ethanol/l was produced from 25.7 g/l of glucose; i.e. the theoretical maximum ethanol yield based on glucan in hydrolyzate was 89.8%. 相似文献
104.
Dong Oh Ha JuDong Yeo Sung Tae Kang Mi‐Ja Kim JaeHwan Lee 《European Journal of Lipid Science and Technology》2012,114(7):780-786
Thermal oxidation of edible oils can generate 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging compounds from oxidized lipids (RSOLs). However, effects of photosensitization on the formation of RSOLs have not been reported yet. Methylene blue (MB) photosensitization and involvement of singlet oxygen and transition metals on the RSOL formations were determined in stripped lard oils. RSOLs were formed in lard containing MB and visible light irradiation only. Addition of sodium azide decreased RSOLs with concentration dependent manner, which implies singlet oxygen was involved on the RSOL formation. Ethylenediammetetraacetic acid (EDTA), a well known metal chelator, accelerated the formation of RSOLs through protecting the decomposition of MB photosensitizer. Results from p‐anisidine values showed that RSOLs from photosensitization may not be formed from the same pathways compared to thermal oxidation. Practical application: Understanding mechanisms of lipid oxidation can help extend the shelf‐life of foods. Photosensitization plays important roles in accelerating the rates of lipid oxidation. The results of this study showed that foods containing photosensitizers can generate radical scavenging compounds from oxidized lipids (RSOLs) under visible light irradiation and singlet oxygen is involved in the formations of these compounds. However, these compounds may not share the same pathways with thermally oxidized lipids. Metal chelating agents accelerated the rates of lipid oxidation and formation of RSOLs which implies that metal chelators can act as prooxidant. Careful considerations are necessary on the addition of metal chelators because non‐polar photosensitizers can act a prooxidant. 相似文献
105.
We investigated the effect of temperature on the efficiency of paclitaxel extraction from biomass. In addition, kinetic and thermodynamic studies of this extraction process were performed. The concentration of extracted paclitaxel increased with increasing extraction temperature and extraction time. When the experimental data were applied to various kinetic models, the hyperbolic model (second-order model) was the most appropriate. The predictive model was developed to predict the concentration of extracted paclitaxel at different temperatures at a given time. The Gibbs free energy change was determined to be negative, while enthalpy change and entropy change were positive. These results indicate that this extraction process is spontaneous, endothermic, and irreversible. 相似文献
106.
Mani Ganesh Pushparaj Hemalatha Peng Mei Mei Krishnan Rajasekar Hyun Tae Jang 《Journal of Industrial and Engineering Chemistry》2012,18(2):684-689
A new type of mesoporous silica nanoparticle (MSN) was synthesized in fluoride media via sol–gel technique using TritonX 100 and Tween-20. The surface area and pore volume of the MSN particles were modified by varying the concentration of Tween-20. The prepared MSN nanoparticles with large surface area and pore volume (T-2, T-3) were selected to accommodate the model drug duloxetine hydrochloride (DX) for evaluation of their drug-loading and release abilities. Calcined and DX loaded nanoparticles were characterized by Brunauer–Emmett–Teller technique (BET), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric (TG) analysis and UV-diffuse reflectance (UV-DRS). In vitro release studies proved that the particle displays an initial burst release followed by sustained release for up to 140 h. From the studies it is evident that the synthesized particle may be useful as a carrier for sustained release of active pharmaceutical ingredients (APIs). 相似文献
107.
108.
Tran Thanh Tung Mickael Castro Jean-Francois Feller Tae Young Kim Kwang S. Suh 《Organic Electronics》2013,14(11):2789-2794
A hybrid of graphene and conducting polymer holds great potential as the active materials for high performance chemical sensor application. In this work, a thin hybrid film of reduced graphene oxide (RG-O) and poly(3,4-ethylenedioxythiophene) (PEDOT) was fabricated by means of vapor phase polymerization and explored as active material for chemical sensors. The chemical sensors based on hybrid film of RG-O and PEDOT are capable of detecting electrical signals caused by the absorption of trace levels of different analyte vapors with high sensitivity, selectivity and fast response. 相似文献
109.
A shape changing material (SCM) morphs its shape upon external stimulus, and it offers a design of complex 3-dimensional structures remotely, which can be potentially useful for biomedical tools, drug delivery, and soft robotics. To actuate such structures through a physicochemical stimulus, stimuli-responsive materials have been studied over the past few decades. Several SCMs have been reported by combining novel stimuli-responsive materials, micropatterning techniques and a unique actuation cue. In this review, we introduce a recent development in SCMs within the aspects of their materials and structures to describe how the materials can be designed and actuated on demand. Finally, we discuss the future direction and challenges for SCMs as physicochemically-powered actuators. 相似文献
110.
Byeung Jun Lim Tae Choon Park Sejin Kwon 《Journal of Mechanical Science and Technology》2014,28(9):3569-3581
Characteristic changes in the stall inception in a single-stage transonic axial compressor with an axial skewed slot casing treatment were investigated experimentally. A rotating stall occurred intermittently in a compressor with an axial skewed slot, whereas spike-type rotating stalls occurred in the case of smooth casing. The axial skewed slot suppressed stall cell growth and increased the operating range. A mild surge, the frequency of which is the Helmholtz frequency of the compressor system, occurred with the rotating stall. The irregularity in the pressure signals at the slot bottom increased decreasing flow rate. An autocorrelation-based stall warning method was applied to the measured pressure signals. Results estimate and warn against the stall margin in a compressor with an axial skewed slot. 相似文献