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991.
剪切场下聚合物结晶形态学研究进展 总被引:3,自引:0,他引:3
聚合物熔体被引入剪切场后,会发生与静态下不同的结晶现象。微观上可以得到伸直链晶体、片晶及串晶;宏观上除了静态下典型的球晶外,还能观察到球晶的变形和柱晶等。另外,剪切还可以使晶体发生晶型转变。本文对聚合物熔体在剪切场下结晶形态学的研究进展进行了介绍。 相似文献
992.
Polymeric substrate materials like polystyrene (PS), polycarbonate (PC) or cyclic olefins (COC) are getting more attention besides silica, glass and ceramic for the preparation of reaction vessels, optical slides, microfluidic components or microtiterplates in applications like medical diagnostics and pharmaceutical drug screening. Actually, the market of transparent polymeric chips is demanding the availability of modified surfaces with well defined arrays of wettable areas or special chemical functionalities. The modified areas are starting point to graft bioactive molecules, for instance proteins or DNA‐oligomers. Another application is pretreatment of adhesive bonded joints. Presently surface modifications are performed chemically and physically by plasma surface interaction. IWS has developed a new technique for dry chemical structuring of polymeric surfaces based on the principle of excimer laser irradiation in reactive gas atmosphere. This technique is characterized by a high resolution and a negligible amount of chemicals. The procedure consists of only a few processing steps, in contrast to conventional lithographic structuring methods. Also wetting problems do not play a role as they do in printing techniques. The technology provides the possibility of tailoring the chemical and topographical surface properties from ultrahydrophobic to hydrophilic or to functionalize areas of choice in the μm range with a chemical group of defined density. Using an excimer‐laser to induce reactions, mask imaging can be applied for microstructuring the surface with new properties, e. g. for microarrays. In addition, the laser allows defined amount of energy into the elementary reaction, according to the wavelength applied, which opens the possibility of replacing atoms in the polymer molecules by other atoms or molecules taken from an agent in the environment, in a selective way. The precondition is that both the polymer and the agent absorb the same wavelength. For instance 193 nm radiation (ArF excimer laser) is absorbed by polyolefines and by ammonia allowing an exchange of H atoms for amino groups by which the surface is changed to starting point to graft bioactive molecules. Chemical microstructures for instance amino group arrays have been realized on a variety of polymeric materials like cyclic olefin foil. This array of monofunctionality is the starting point for the preparation of parallel microreactors. These samples of topographical and chemical microstructures are the first step for biochemical preparations in medical diagnostic kits, DNA‐, protein‐ or cell biochips. The upscaling of the laser modification process in a multi‐chamber reactor offers the semicontinuous functionalization of polymers in pilot scale or in batch processing. On this basis the surface modification step can be adapted into a mass production line of “Lab‐on‐a‐chip” systems. 相似文献
993.
994.
电池用含稀土铝合金阳极性能的研究 总被引:2,自引:0,他引:2
通过向 99.99%的纯铝中添加稀土及其它一些合金元素 ,如Ga,In ,Mg ,Sn ,Zn等 ,制得一系列含稀土的合金。在 2 5℃ ,4mol·L- 1 的KOH溶液中测定了它们的开路电位、自腐蚀速度与电化学性能。结果表明 :稀土元素能显著提高铝合金的抗腐蚀能力和阳极效率 ,Al 5Zn 0 0 1 5In 0 .1Sn 1Mg 0 .3RE具有较好的综合性能。 相似文献
995.
西宁特钢采用60 t Consteel电弧炉-60 t LF(VD)-700 kg铸锭工艺生产60Si2CrVAT弹簧钢(%)0.56~0.64C,1.40~1.80Si,0.90~1.20Cr,0.10~0.19V,≤0.020P,≤0.020S.Consteel电弧炉偏心底出钢留渣作业,熔炼温度控制在1 560~1 590 ℃,冶炼全过程泡沫渣长弧操作,可使电弧炉出钢时钢水中磷含量≤0.015%,LF精炼时加铝脱氧,氩气搅拌,控制钢中全铝含量为0.025%~0.050%,并经VD处理使钢中氧含量达(9~12)×10-6,氢含量为(0.6~0.9)×10-6.检验结果表明,钢中A细类夹杂≤1.0级,B细类夹杂为0.5级,其余为0级. 相似文献
996.
997.
InGaAs/InP HBT材料的GSMBE生长及其特性研究 总被引:3,自引:0,他引:3
本文报道了采用气态源分子束外延 (GSMBE)技术生长InGaAs/InP异质结双极晶体管 (HBT)材料及其特性的研究。通过对GSMBE生长工艺的优化 ,在半绝缘 ( 10 0 )InP衬底上成功制备了高质量的InGaAs/InPHBT材料 ,InGaAs外延层与InP衬底的晶格失配度仅为 4× 10 - 4量级 ,典型的InP发射区掺杂浓度 ( 4× 10 1 7cm- 3)时 ,电子迁移率为 80 0cm2 ·V- 1 ·s- 1 ,具有较好的电学特性 ,可以满足器件制作的要求。 相似文献
998.
分析了华能南通电厂350MW机组原高压加热器控制和保护系统存在的缺陷,并提出了具体的改进方案:(1)淘汰气动控制器,以DCS实现其控制;(2)改进高压加热器危急疏水方式;(3)增加变送器数量;(4)改进保护逻辑和保护参数的设定。改进后的系统运行情况良好。 相似文献
999.
1000.
Based on the fatigue prediction model of exponential function and Whitney-Nuismer(WN) criterion of static strength for the composite material laminate with a circular hole, the stress correct factor (β) was put forward and a new fatigue prediction model for composite material laminate was set up. T300/KH304, which is recently studied and is a high capability composite material, was used as the raw material. In order to gain the factor β, the fatigue experiments of the laminates with holes in different diameters and the same ratio of width to diameter were conducted. The fatigue analysis and tests of the laminates with a hole 5 mm in diameter are carried out at different stress levels, and the results meet the engineering requirement. The simple, prompt and practical method is provided for the prediction of S-N curve of composite laminate with a circular hole. 相似文献