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111.
Billur Sakintuna Okan Budak Tunay Dik Füsun Yöndem-makascioğlu N. Suzan Kincal 《Chemical Engineering Communications》2013,200(5-8):883-897
The enzymic hydrolysis of commercial wheat starch and freshly prepared wheat starch fractions was studied in batch and flow systems. Fresh starch was prepared by wet separation of wheat flour into starch milk and gluten, followed by processing the starch milk using a serially connected hydrocyclone system to produce underflow and overflow streams. The underflow stream consisted mainly of the larger (> 30 w m) granules, while the overflow stream contained only the smaller (< 10 w m) granules. In batch system, the hydrolysis behavior of wheat starch fractions was investigated under the action of Sigma f -amylase ( Bacillus licheniformis ), either as soon as they were prepared or after spray drying. The two fractions of fresh wheat starch showed different hydrolysis behavior, the difference getting larger as the separation improves. Underflow streams were found to be much more susceptible to hydrolysis than overflow streams, regardless of whether the hydrolysis was carried out right away or on dried samples, and also regardless of whether rinsing was applied. In flow system, dried underflow stream and commercialwheat starch were hydrolyzed using Orbamil-T ( Bacillus licheniformis ), Orbamil-BHT ( Bacillus stearothermophilus ), and Sigma f -amylase ( Bacillus licheniformis ). Hydrolysis of fresh starch was found to be significantly faster than commercial wheat starch. Commercial f -amylase Orbamil-T was found to be almost as effective as the purified Sigma f -amylase. 相似文献
112.
Since pervaporation process is the coupling of solution and diffusion mechanisms, a sorption study was carried out with membranes prepared by cross-linking polyvinylalcohol (PVA) and polidimethylsiloxane (PDMS). Tartaric acid (Tac) was used as the cross-linking agent for PVA, and a commercial cross-linking agent was used for PDMS. Sorption experiments were carried out at 30-50°C temperature range in pure water and ethyl acetate using the films prepared. The PVA and PDMS films prepared preferentially sorb water and ethylacetate, respectively. A pervaporation study at 30°C was carried out for pure ethylacetate and pure water, and mixtures of ethylacetate containing 2 and 2.5 wt% water using 100 w m thick PVA membrane. The results indicate that the PVA membrane prepared is extremely selective for water. 相似文献
113.
Zeynep Karahaliloğlu Murat Demirbilek Mesut Şam Melike Erol‐Demirbilek Necdet Sağlam Emir Baki Denkbaş 《应用聚合物科学杂志》2013,128(3):1904-1912
The design and the development of novel scaffold materials for tissue engineering have attracted much interest in recent years. Especially, the prepared nanofibrillar scaffold materials from biocompatible and biodegradable polymers by electrospinning are promising materials to be used in biomedical applications. In this study, we propose to produce low‐cost and cell‐friendly bacterial electrospun PHB polymeric scaffolds by using Alcaligenes eutrophus DSM 545 strain to PHB production. The produced PHB was characterized by Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared Spectroscopy (FTIR). Nanofibrous scaffolds were fabricated via electrospinning method that has a fiber diameter approximately 700–800 nm. To investigate cell attachment, cell growth, and antioxidant enzyme activity on positively and negatively charged PHB scaffold, PHB surface was modified by plasma polymerization technique using polyethylene glycol (PEG) and ethylenediamine (EDA). According to the results of superoxide dismutase (SOD) activity study, PEG‐modified nanofibrillar scaffolds indicated more cellular resistance against oxidative stress compared to the EDA modification. As can be seen in cell proliferation results, EDA modification enhanced the cell proliferation more than PEG modification, while PEG modification is better as compared with nonmodified scaffolds. In general, through plasma polymerization technique, surface modified nanofibrillar structures are effective substrates for cell attachment and outgrowth. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
114.
To investigate the reinforcing effect of nanoflower-like hydroxyapatite (NFHA) in resin-based dental composites, we synthesized a novel NFHA using microwave irradiation (MW), hydrothermal treatment (HT), and sonochemical synthesis (SS). Silanized NFHA was then used as the reinforcing filler in dental resin composites. We characterized the structure and morphology of various HA nanostructures using x-ray diffraction, scanning electron microscope, and TEM. The mechanical performance of dental resin composites reinforced with silanized NFHA was measured using a universal testing machine. Spherical HA, synthesized through chemical precipitation (CP), served as the control group. One-way analysis of variance was employed for the statistical analysis of the acquired data. The results demonstrate that the nanoflower morphology significantly was improved mechanical and physical properties. After conducting trials, the NFHA synthesized using MW and HT showed a substantial enhancement in mechanical and physical properties compared to the other structures. Therefore, it can be concluded that NFHA can serve as a novel reinforcing HA filler, providing regenerative properties to resin composites with sufficient mechanical strength. 相似文献
115.
116.
Y. Junejo E. Karaoğlu A. Baykal Sirajuddin 《Journal of Inorganic and Organometallic Polymers and Materials》2013,23(4):970-975
Ag(0) NPs were prepared by chemical reduction method in which silver nitrate was taken as the metal precursor and cefditorene as a reducing/capping agent and NaOH as the catalyst for reaction enhancement. The formation of the Ag(0) NPs was monitored using UV–Vis absorption spectroscopy confirmed the formation of Ag(0) NPs by exciting the typical surface plasmon absorption maxima at 405 nm. Transmission electron microscopy (TEM) confirmed the spherical morphology of the (Ag(0) NPs). The crystallite (11 ± 3 nm) and particle size (14.1 ± 2.2 nm) obtained from TEM and XRD analysis were coinciding with each other. Prepared Ag(0) NPs were then used as catalyst against 2-nitroaniline, 3-nitroaniline and 4-nitroaniline, which all showed best catalytic activity. 相似文献
117.
Nilgün Kzlcan Belks Ustamehmetolu Nesrin
z A. Sezai Sara Ahmet Akar 《应用聚合物科学杂志》2003,89(11):2896-2901
Soluble and processable conductive copolymers of silicone tegomers and pyrrole were developed. This was easily accomplished by the oxidative polymerization of pyrrole monomer by Ce(IV) salt in the presence of silicone tegomers with hydroxyl chain ends. The resulting copolymers were soluble in dimethylformamide. The products were characterized by Fourier transform infrared, 1H‐NMR, and four‐point probe conductivity, and their surface properties were investigated with contact‐angle measurements. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2896–2901, 2003 相似文献
118.
Photolytic and free‐radical polymerization of cinnamate esters of epoxidized plant oil triglycerides
Epoxidized soybean oil was reacted with cinnamic acid with triphenyl phosphine as a catalyst. Cinnamic acid reacted with 79% of the available epoxy groups, and this yielded cinnamate esters of epoxidized soybean oil (ESOCA). 1H‐NMR, IR, and mass spectra of the new cinnamate derivatives confirmed the proposed structure. The mass spectra revealed that the average number of cinnamate groups per triglyceride molecule was 3.33. ESOCA could be photopolymerized with UV light. ESOCA could also be homopolymerized into a soft and insoluble polymer by free‐radical initiation and copolymerized with styrene, vinyl acetate, and methyl methacrylate. A mixture of ESOCA with 25 wt % styrene had a viscosity of 410 cP and could be free‐radically polymerized with benzoyl tert‐butyl peroxide at elevated temperatures. Differential scanning calorimetry confirmed the formation of copolymers. The ESOCA homopolymer and its copolymers all showed a first‐order transition by differential scanning calorimetry around ?1.5°C that was attributable to side‐chain relaxations of the triglyceride fatty acids. The styrene copolymer of ESOCA showed a tan δ peak at 66.6°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3882–3888, 2003 相似文献
119.
Mehmet Uysal Ramazan Karslioğlu Ahmet Alp Hatem Akbulut 《Ceramics International》2013,39(5):5485-5493
Core–shell nanostructured Ni-coated Al2O3 composite powders were synthesised by using the electroless plating method. The influence of the chemical components and powder concentration in the Ni coating was investigated by scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction techniques. The results show that the concentration of the plating components plays an important role in the formation of core–shell Al2O3/Ni composite powders. The nickel content in the composite powders could be effectively controlled by adjusting the nickel chloride content and the concentration of NaH2PO2·H2O in the plating solution. The nanostructure of the crystalline Ni coatings was observed to be very attractive for achieving good bonding between ceramic particles and matrices for composite production. 相似文献
120.