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911.
B. K. Prasad 《Tribology Letters》2007,25(2):103-115
This study pertains to the observations made during the sliding wear response of a zinc-based alloy in different test conditions.
The effects of sliding speed and load on the wear behaviour of the alloy have been studied. The properties evaluated were
wear rate, frictional heating and coefficient of friction. The wear performance of the zinc-based alloy has been compared
with that of a conventional cast iron in identical test conditions.
The wear rate of the samples increased with applied load and sliding speed while the seizure resistance (load) deteriorated
with speed. The zinc-based alloy exhibited less wear rate and reduced frictional heating than that of the cast iron while
friction coefficient followed a reverse trend. Observed wear response of the samples has been discussed in terms of specific
features like lubricating, load carrying, microcracking and thermal stability of various microconstituents of the samples,
and substantiated further through the features of wear surfaces, subsurface regions and debris. 相似文献
912.
论述了建造用于制造不锈钢、铝、铜、镍、钛及其合金压力容器清洁厂房的重要性和必要性 ,提出了压力容器清洁厂房的建造要求及管理规定 ,给出了清洁厂房的部分考核依据。 相似文献
913.
低温高铁锰氨氮地下水两级生物净化工艺 总被引:2,自引:1,他引:1
针对"一级曝气+一级过滤"生物净化工艺处理低温(5~7.8℃)、高氨氮(ρ(NH_3-N)3.0 mg/L)、高铁锰(ρ(总Fe)12 mg/L,ρ(Fe~(2+))8.0 mg/L,ρ(Mn~(2+))3.0 mg/L)地下水出水锰和氨氮超标问题,开展两级曝气+两级过滤"净化工艺启动和铁锰氨氧化活性去除区位研究.两级生物净化工艺经133 d驯化培养启动成功,锰是影响启动周期长短的主要因素.启动成功后,氨氮去除负荷可达29.66 g/(m~2·h),锰去除负荷可达27.08 g/(m~2·h),产水量是单级净化工艺的2倍.铁锰氨氧化活性去除区位表明,铁在一级滤柱0~50 cm滤层内去除至痕量;55.23%的氨氮在一级滤柱中去除,主要集中在滤层0~135 cm段,44.10%的氨氮在二级滤柱中去除,主要集中在滤层0~50 cm段.锰和氨氮在氧化去除过程中存在显著分级,ρ(NH_3-N)2.25 mg/L时,会显著抑制锰氧化菌(MnOB)活性.锰在各级滤柱中的去除率和去除区位受进水氨氮质量浓度及滤速影响较大,滤柱启动成功后,仅有5.53%的锰在一级滤柱中去除,89.34%的锰在二级滤柱中去除. 相似文献
914.
为了探究基体材料纳米化对镀层性能的影响,采用直流电沉积方法在纳米晶工业纯铁和粗晶工业纯铁上制备了不同厚度的Ni镀层.利用扫描电子显微镜与X射线衍射仪观察并分析了镀层的组织形貌和结构.采用电化学测试和静态浸泡方法对基体和镀层进行了耐腐蚀性能研究.结果表明,纳米晶工业纯铁的基体及其Ni镀层的耐腐蚀性能略优于相同厚度下粗晶工业纯铁的基体及其Ni镀层,但随着镀层厚度的增加,这种差异逐渐减小.同时随着镀层厚度的增加,镀层表面越来越平整致密. 相似文献
915.
Bacterial polysaccharides and polyhydroxyalkanoates present physical and chemical characteristics that impart them diverse functional properties, including the ability to produce structures from nano- to macroscale (e.g., spheres, capsules, beads). Such structures may be specially designed to fulfill the requirements of specific applications in different areas, either alone or conjugated with other polymers by means of ionic interactions, hydrogen bonding, or chemical reactions. The interest on using such biomaterials has been increasing due to their unique functional properties, nontoxicity, biodegradability, and biocompatibility. The fields of application of bacterial polymers-based structures include drug delivery, biomedicine, food products, environment, and agriculture, among others. 相似文献
916.
Preparation of polypropylene‐based nanocomposites using nanosized MCM‐41 as support and in situ polymerization 下载免费PDF全文
Darío M González Raúl Quijada Mehrdad Yazdani‐Pedram Joao Paulo Lourenço M Rosario Ribeiro 《Polymer International》2016,65(3):320-326
MCM‐41 nanoparticles were used for preparing nanocomposites through the in situ polymerization of propylene. The performance of the catalytic system and the final properties of the materials obtained are highly dependent on the methodology used for impregnation of the catalyst onto the support particles, and therefore an optimization study for the impregnation methodology of the catalyst (Me2Si(Ind)2ZrCl2) was carried out. Two different methodologies were used; the results in terms of catalytic activity and polymer molecular masses indicated that the most promising one involved the pre‐activation of the catalyst with the cocatalyst, methylaluminoxane, followed by impregnation onto the MCM‐41 nanoparticles. Thus, an optimized route for the preparation of polypropylene nanocomposites achieving significant improvements in catalyst activity was developed. The nanocomposite materials were characterized by GPC, TGA and DSC. The dispersion state and the size of the nanoparticles incorporated in the polypropylene matrix were investigated by transmission electron microcopy. Additionally, this methodology allows simultaneous control of the desired amount of support and the concentration of catalyst to be used in the in situ polymerization. © 2015 Society of Chemical Industry 相似文献
917.
Peipei Li 《Journal of Experimental Nanoscience》2016,11(1):18-27
In this work, Cu2O nanoparticles of a particular shape were prepared by an eco-friendly, gentle and low-cost synthetic method using lignin as a reducing and capping reagent. Structure and morphology of the Cu2O nanoparticles were characterised by high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction (XRD) and Fourier-transform (FT-IR) spectroscopy. The results established that Cu2O nanoparticles coated by lignin showed a particular shape. The morphology of Cu2O nanoparticles presented as some loose accumulation of particles just like broccoli, and the particle size range was between 100 and 200 nm. And, the XRD revealed the structure of crystalline of the Cu2O nanoparticles. In addition, the sterilisation of Cu2O nanoparticles on Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) was also investigated. The Cu2O nanoparticles showed effective bactericidal activity against E. coli and S. aureus. The antibacterial rate could get 100% after 30 min with 4.0 g/L Cu2O nanoparticles. Furthermore, the Cu2O nanoparticles were confirmed to have low cytotoxicity. 相似文献
918.
We have investigated the low-temperature behavior of the optical and magneto-optical properties of (Bi, Gd, Al)-substituted yttrium iron-garnet films that are either single or microresonator, i.e. sandwiched between two dielectric Bragg mirrors. It was shown that the magneto-optical properties of the microresonators with a magnetic film core are mainly determined by the properties of the constituent magnetic films. Special attention was paid to the compositions possessing magnetic compensation temperatures. The phenomenon of the temperature hysteresis was found and discussed for several samples. This testifies the fact that the magnetic moment reorientation in a magnetic field occurs by the full cycle of the first-order phase transitions “collinear phase – non-collinear phase – collinear phase”. The Faraday hysteresis curves at around magnetic compensation temperatures are demonstrated to be very informative concerning composition of a sample. In particular, the hysteresis curves measured for the magnetic films on the garnet substrates showed bursts that indicates formation of a transition layer. 相似文献
919.
Goshtasp Cheraghian 《Petroleum Science and Technology》2016,34(3):260-267
Nanotechnology has the potential to profoundly change enhanced oil recovery and to improve mechanism of recovery, and it is chosen as an alternative method to unlock the remaining oil resources and applied as a new enhanced oil recovery method in last decade. The objective of this research is identification of potential of nanotitanium dioxide as an appropriate agent for improving the efficiency of surfactant flooding in five-spot glass micromodels. In this work a series of solvent injection experiments was conducted on horizontal glass micromodels at same conditions. Surfactant solutions and newly developed nanosurfactant solutions with 1600–2000 ppm sodium dodecyl sulfate were tested. Observations showed that nanotitanium dioxide has appropriate performance in enhancing the oil recovery at surfactant solution, near critical micelle concentration conditions. Also The results of experiments illustrated improvement of heavy oil recovery in micromodel test with nanotitanium dioxide (51.0%). 相似文献
920.