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81.
E. Lin H. B. Parizi A. Pourmousa S. Chandra J. Mostaghimi 《Journal of Coatings Technology and Research》2011,8(6):697-706
Applying a thin, protective coating of a nontoxic, chemically resistant epoxy to the interior of existing pipes is an alternative
method to pipe replacement. In order to find the controlling parameters in this method, in this study, viscous epoxy was propelled
by compressed air through clear polyvinyl chloride (PVC) pipes. Epoxy flow was annular, and it hardened to form a thin, uniform
coating on the inner pipe surface. A video camera was employed to record fluid motion, and the thickness of the coating was
measured using an image analysis program named ImagJ. Tests were done with varying air temperature, airflow rate, piping configuration,
and epoxy temperature. A one-dimensional numerical algorithm was developed to model fluid flow, heat transfer, and epoxy curing.
Heating the epoxy makes it move faster because liquid viscosity decreases with increasing temperature. The coating was significantly
thicker at the bottom of a horizontal pipe than at the top due to sagging of the epoxy coating after it had been applied,
resulting in flow from the top to the bottom of the pipe. Sagging could be reduced by maintaining airflow until curing was
almost complete and the epoxy had hardened enough to prevent it from moving easily. The combination of the experimental results
and numerical modeling showed that the most important parameters controlling the speed of the epoxy and coating thickness
were the air flow rate and temperature, since they determine the shear forces on the epoxy layer and the rate at which the
epoxy cures. Raising air temperature increases the reaction rate and therefore decreases the time required for the epoxy to
cure inside the pipe. The results of the simulation showed a very good agreement with the experimental results in pipes with
1-in diameter or less. 相似文献
82.
The effect of a number of thiophosphoryl compounds [viz., bis(isobutyl) thiophosphoryl di‐, tri‐, and tetrasulfides and bis(dicyclohexyl) thiophopsphoryl di‐, tri‐, and tetrasulfides] on natural rubber (NR)‐carboxylated nitrile rubber (XNBR) blend was studied. All these thiophosphoryl compounds are capable of forming interrubber links leading to covulcanized blends which exhibit a fair degree of synergism with respect to physical properties, the maximum being obtained at the 25% NR and 75% XNBR blend composition. This is an obvious claim that the blend under investigation is technologically compatible, having some degree of interrubber interaction which is enhanced in case of two‐stage vulcanization. The existence of interrubber interaction is judged by the swelling experiment. The blend morphology assessed by SEM micrographs corroborates the foregoing observations and accounts for the significant improvement in physical properties of the blend vulcanizates, particularly in two‐stage vulcanization. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3286‐3299, 2002 相似文献
83.
Chattopadhyaya Rajagopal; Ghose Asoke Chandra 《Protein engineering, design & selection : PEDS》2002,15(4):297-304
A complete three-dimensional model (RCSB001169; PDB code 1qqz) for the Vibrio cholerae toxin coregulated pilus protein (TcpA),including residues 1197, is presented. We have used thecrystal structure of the Neisseria gonorrhoeae pilin (PilE),available biochemical data about TcpA, variations in the primarysequences of TcpA among various Vibrio cholerae strains andsecondary structure prediction, hydrophilicity, surface probabilityand antigenicity plots for TcpA to build our model. In our TcpAmodel, the first 137 residues possess a structure similar tothe PilE, but the remainder is different. Though the ladle shapeis still preserved, TcpA possesses a larger ladle head or globulardomain compared to PilE. Using this model, it has been possibleto identify two kinds of conserved residues: (i) those formingthe core of the TcpA monomer and (ii) those involved in themonomermonomer interactions leading to fibre formation.Residues on the fibre exterior, important in the mediation ofbacterium (pilus)bacterium (pilus) and bacterium (pilus)hostinteractions, show more variability in comparison to those of(i) and (ii). 相似文献
84.
Chandra Wahyu Purnomo 《Journal of Porous Materials》2013,20(5):1305-1313
Bagasse fly ash (BFA), a solid waste from sugar cane industries, contains significant amount of carbon as well as silica. The coarse particles with high carbon content can be separated and further activated to produce BFA-based activated carbon, while silica content can be extracted from fine BFA particles to be used for zeolite crystallization. The zeolite crystal may be grown on a suitable solid surface to create a zeolitic composite. In this study, silicate extract from fine BFA particles were combined with pretreated carbon rich coarse BFA particles in a hydrothermal crystallization process to produce particular carbon–zeolite composites. The carbon rich particles could be subjected to any necessary activation or surface treatment before being used in the composite preparation. Meanwhile, a simple method based on thermogravimetry is proposed to evaluate the zeolite particles distribution on the carbon surface. Furthermore, the composite ability for treating mixed organic and inorganic pollutants in aqueous solution has been investigated. 相似文献
85.
Fabrication and characterization of high energy density supercapacitor based on graphite oxide/polypyrrole (GO/PPy) composites is reported. Improvement in charge storage has been obtained by exfoliation of graphite oxide sheets via intercalation of polypyrrole. The formation of composite has been shown by the analysis of X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and Fourier transfer of infrared spectroscopy data. Scanning electron and transmission electron microscopy clearly show sheet-like layered structure of graphite oxide surrounded by polypyrrole. Supercapacitors fabricated using this composite system result in a reduced equivalent series resistance value ~1.85 Ω. Such low value can be attributed to the intercalation of conducting polypyrrole into the graphite sheets. A specific capacitance of ~181 F g?1 in 1 M Na2SO4 aqueous electrolyte with a corresponding specific energy density of ~56.5 Wh kg?1 could be achieved. These values make GO-based materials suitable for their use as electrodes in high performance supercapacitors. 相似文献
86.
Taofeek Mukaila Adewale Adeniyi Ibrahim Bello Niloy Chandra Sarker Ewumbua Monono Ademola Hammed 《应用聚合物科学杂志》2024,141(19):e55345
Plastic-induced environmental issues could be solved using biomaterials, such as polylactic acid (PLA) film. PLA film is a costly solution suggesting the need to add less expensive starch. However, PLA and starch do not mix due to their diverging water behavior. In this study, we evaluated the impact of lecithin as a compatibilizer in varying ratio of PLA and starch film. The results show that inclusion of lecithin in PLA/starch composite leads to enhanced mechanical properties compared with the composite without lecithin. All films' thermal properties were stable but the thermograph of PLA/starch display two peaks whose distance is impacted by lecithin. In addition, morphology and functional group fingerprints revealed that the addition of lecithin improved the interfacial adhesion between the two polymers. Lecithin influenced the positioning and dispersion pattern of starch granules and distinct transmittance characteristics. The improved compatibility of PLA/starch makes the resulting films less susceptible to water penetration and dissolution. This work demonstrated the possibility of using lecithin as emulsifier between PLA and starch which could expand the application of PLA/starch film especially in packaging industries and bale net wrapping. 相似文献
87.
The present study was designed to systematically compare the conventional and reverse transfection methodologies for chitosan/DNA complexes using a low molecular weight (MW) chitosan. The hydrodynamic diameter of the complexes, measured by Dynamic Light Scattering (DLS) was found to be ~ 216 nm and TEM investigations showed spherical and compact complexes with an average size of 200 nm. The transfection efficiency of chitosan using the two methodologies was assessed by employing reporter gene coding for green fluorescent protein (GFP) and luciferase. More than 50% of HEK 293 cells were transfected when transfection done using reverse transfection strategy at pH 6.5 with 10% serum for 24 h followed by media replenishment with pH 7.4 with 10% serum for an additional 24 h period. Also, the cytotoxicity of chitosan/DNA complexes was also considerably lower than the commercially available transfection reagent lipofectamine. Our investigation concludes that maximal transgene expression levels could be achieved using reverse transfection where the chitosan/DNA complexes are pre‐incubated on the plate surface followed by plating of cells at pH 6.5 with 10% serum for 24h and media resupplemented with pH 7.4 with 10% serum for an additional 24 h period. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
88.
B N V S Ganesh Gupta K Mritunjay Maharudrayya Hiremath Rajesh Kumar Prusty Bankim Chandra Ray 《应用聚合物科学杂志》2020,137(43):49318
Polymer hybridization technique, consisting of an interlayer arrangement of different polymers, acts as the most economical and promising technique in augmenting the glass fiber-reinforced polymer composite's mechanical properties. This investigation focuses on the effect of cure kinetics on the flexural behavior of glass-polymer hybrid (GPH) composite, and also elucidates the comparative analysis on the mechanical behavior of glass-epoxy (GE) composite, glass-vinyl ester (GVE) composite, and GPH composite. The optimal postcuring temperature has been found to be 200°C for GPH composite among the other postcuring temperatures conducted at 140, 170, and 230°C. Among all these abovementioned composites, highest flexural strength and interlaminar shear strength properties have been recorded by the 200°C postcured GPH composite leading to 10.87 and 18.76% increment, respectively, compared with GE composite. Furthermore, thermomechanical characterization has been done to know the viscoelastic behavior of the GPH composite postcured at different temperatures using dynamic mechanical thermal analysis. The fracture morphology of flexural tested composite samples demonstrated a combination of failure modes. Relevant information on the chemical restructuring and fracture morphology of experimented composite material using Fourier-transform infrared (FTIR) spectroscopy and Scanning electron microscopy (SEM) has also been studied. 相似文献
89.
Polash Chandra Karmakar Jin Seop Ahn Yong-Hee Kim Sang-Eun Jung Bang-Jin Kim Hee-Seok Lee Buom-Yong Ryu 《International journal of molecular sciences》2020,21(22)
Exposure to bisphenol A (BPA) in the gestational period damages the reproductive health of offspring; detailed evidence regarding BPA-induced damage in testicular germ cells of offspring is still limited. In this study, pregnant mice (F0) were gavaged with three BPA doses (50 μg, 5 mg, and 50 mg/kg body weight (bw)/day; tolerable daily intake (TDI), no-observed-adverse-effect-level (NOAEL), and lowest-observed-adverse-effect level (LOAEL), respectively) on embryonic days 7 to 14, followed by investigation of the transgenerational effects of such exposure in male offspring. We observed that the NOAEL- and LOAEL-exposed F1 offspring had abnormalities in anogenital distance, nipple retention, and pubertal onset (days), together with differences in seminiferous epithelial stages and testis morphology. These effects were eradicated in the next F2 and F3 generations. Moreover, there was an alteration in the ratio of germ cell population and the apoptosis rate in germ cells increased in F1 offspring at the LOAEL dose. However, the total number of spermatogonia remained unchanged. Finally, a reduction in the stemness properties of spermatogonial stem cells in F1 offspring was observed upon LOAEL exposure. Therefore, we provide evidence of BPA-induced disruption of physiology and functions in male germ cells during the gestational period. This may lead to several reproductive health issues and infertility in offspring. 相似文献
90.
Ganguly Sayan Ghosh Sabyasachi Das Poushali Das Tushar Kanti Ghosh Suman Kumar Das Narayan Chandra 《Polymer Bulletin》2020,77(6):2923-2943
Polymer Bulletin - Electrically conducting flexible polymeric nanocomposite has been fabricated through wet mixing method where conducting inclusion was acoustically exfoliated pristine graphene... 相似文献