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基于桩承式路堤平面土拱效应研究的室内模型试验,采用PFC2D软件建立桩承式路堤颗粒流数值分析模型,通过与试验结果对比验证了该数值分析模型的正确性。首先,基于路堤自重应力荷载作用下的颗粒流数值模拟结果,验证了平面土拱效应内拱与外拱高度理论计算公式的正确性。然后从路堤中竖向应力的分布规律、应力缩减比的变化规律以及路堤中接触力的分布规律三个角度分析了路堤表面外加荷载作用下桩承式路堤中土拱效应的演变规律。研究发现:当路堤表面外加荷载由10 kPa增大至40 kPa时,桩承式路堤中的土拱效应发挥稳定;当路堤表面外加荷载由40 kPa增大至100 kPa时,桩承式路堤中的土拱结构发生了退化并有新的土拱结构形成,在宏观上表现为软土承担竖向荷载的分担比呈现增大的趋势。 相似文献
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选取某款弱化沟槽呈“H”形的聚碳酸酯/丙烯腈?丁二烯?苯乙烯共聚物(PC/ABS)合金材质安全气囊盖板为研究对象,并构建了其有限元仿真模型,对比有限元力学仿真分析结果与理论计算值验证了该有限元仿真模型的可靠性;通过ISIGHT软件集成Catia和ANSYS,选取安全气囊盖板弱化沟槽的横向长度、深度,纵向长度、深度4个参数作为设计变量,选取弱化沟槽横向最大应力与纵向最大应力作为响应变量,分析了设计变量对响应变量的贡献度分布特征并采用NSGA遗传算法对响应变量多目标优化。结果表明,横向长度、纵向深度对横向最大应力为负贡献度,横向深度、纵向长度为正贡献度;横向深度、纵向长度对纵向最大应力为负贡献度,横向长度、纵向深度为正贡献度;在合理范围内,4个参数值的优化设计,实现了横向最大应力提高和纵向最大应力降低的多目标优化,有效减少了安全气囊盖板爆破时产生的碎屑量,提升了产品的安全性能。 相似文献
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安徽海螺集团水泥股份公司2台Φ4.2m×14.5m水泥磨于2010年9月投产,生产初期,磨机工况不稳定,技经指标不理想。经分析各方面的影响因素,采取了一系列针对性措施,磨机工况、技经指标有了明显改善和提高。 相似文献
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This article presents a experimental study on the removal of hydrogen sulphide (H2S) from high salinity wastewater by emulsion liquid membrane (ELM). The ELM contains diethanolamine (DEA) as carrier, kerosene as solvent and span 80 as surfactant. The fundamental parameters (viz. surfactant concentration, carrier concentration, strip phase concentration, phase ratio, agitation speed and time) affecting the removal of H2S were investigated to select the optimum combination of process parameters. The results showed the optimal governing parameters were: inner phase NaOH aqueous solution 2.0 wt%, Surfactant (span 80) 5.0 vol%, carrier (DEA) 6.0 vol%, treat ratio 1:5, agitation speed 250 rpm, agitation time 15 min, respectively, and removal efficiency of 97.3% was achieved. © 2011 Canadian Society for Chemical Engineering 相似文献
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In this work, acrylic/acrylate copolymeric surfactants, which can be used in the preparation of pesticide oil‐in‐water emulsions (EW), were synthesized by emulsion polymerization, using potassium persulfate (K2S2O8) as an initiator, dodecyl mercaptan (DDM) as a chain transfer agent at the temperature range of 82–85°C. When the weight ratio of monomers was m(butyl acrylate) : m(methyl methacrylate) : m(acrylic acid) = 4 : 4 : 1.6 and the dosage of DDM was 2% (percentage of monomer mass), the prepared acrylic/acrylate copolymeric surfactants had a number‐average molecular weight of 2.5 × 104 and exhibited good stability for pesticide EW. The carboxylic group distribution studies show that only the surface carboxylic groups make dispersed pesticide oil droplets more stable. The acrylic/acrylate copolymeric surfactants prepared by shot‐monomer had the most surface carboxylic group distribution (46.6%). To obtain greater surface carboxylic group distribution, maleic anhydride (MA) was used to modify the polymer system. Adding 2% MA (percentage of monomer mass) to the polymerization system, the surface carboxylic groups were increased 12% over unmodified acrylic/acrylate copolymeric surfactants. Compared with traditional pesticide EW, the avermectin EW prepared with acrylic/acrylate polymeric surfactant had much better stability. Meanwhile, its pesticide effect was similar to that of a control (1.8% abamectin emulsifiable solution). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
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以赤泥、粉煤灰为主要胶凝材料,掺入适量激发剂(石灰)和脱硫石膏,制备了性能优异的赤泥基胶凝材料,并优化了配合比,研究了赤泥基胶凝材料的力学性能、体积稳定性和抗渗性.研究表明赤泥掺量65%,粉煤灰掺量20%,石灰掺量10%,脱硫石膏掺量5%时赤泥基胶凝材料的28 d抗压强度达到3.4 MPa,劈裂抗拉强度达到1.11 MPa.而赤泥掺量65%,粉煤灰掺量25%,石灰掺量5%,脱硫石膏掺量5%时,赤泥基胶凝材料的28 d干燥收缩为115×10-6 m,28 d温度收缩在-20~40℃ 范围内最小为40×10-6 m/℃,空气渗透系数为9.79×10-10 cm/s,抗水渗透系数为1.02×10-6 cm/s.研究表明在适量掺加石灰和脱硫石膏,有利于提高粉煤灰的水化,提高结构密实度,提高了赤泥基胶凝材料的力学性能、体积稳定性和抗渗性. 相似文献
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The miscibility and morphology of poly(caprolactone) (PCL) and poly (4-vinylphenol) (PVPh) blends were investigated by using differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy and 13C solid state nuclear magnetic resonance (NMR) spectroscopy. The DSC results indicate that PCL is miscible with PVPh. FTIR studies reveal that hydrogen bonding exists between the hydroxyl groups of PVPh and the carbonyl groups of PCL. 13C cross polarization (CP)/magic angle spinning (MAS)/dipolar decoupling (DD) spectra of the blends show a 1 ppm downfield shifting of 13C resonance of PVPh hydroxyl-substituted carbons and PCL carbonyl carbons with increasing PCL content. Both FTIR and NMR give evidence of inter-molecular hydrogen bonding within the blends. The proton spin-lattice relaxation in the laboratory frame, T1(H), and in the rotating frame, T1ρ(H), were studied as a function of the blend composition. The T1(H) results are in good agreement with thermal analysis; i.e. the blends are completely homogeneous on the scale of 50-80 nm. The T1ρ(H) results indicate that PCL in the blends has both crystalline and amorphous phases. The amorphous PCL phase is miscible with PVPh, but the PCL crystal domain size is probably larger than the spin-diffusion path length within the T1ρ(H) time-frame, i.e. larger than 2-4 nm. The mobility differences between the crystalline and amorphous phases of PCL are clearly visible from the T1ρ(H) data. 相似文献