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991.
Low‐Energy Electron Beam Induced Charging and Secondary Electron Emission Properties of FEP Film Used on Satellite Surfaces 下载免费PDF全文
Many kinds of insulating materials are used outside a spacecraft. They include FEP films, polyimide films, and so on, and are used as thermal control materials. These materials are exposed to a charged‐particle environment around the spacecraft. Thus then become charged due to charged particles, especially electrons. It has been pointed out that charging of these materials is likely to cause discharges on the surfaces. From this viewpoint, we investigated the charging potential characteristics of 127‐μm‐thick FEP film, a typical thermal control material, by exposing it to electron irradiation at various energies below 20 keV. In the dependence of the charging potential on the electron energy, we found that the electron energy at which no charge‐up occurs is about 2.7 keV. This appears to be the energy at the which secondary electron emission yield becomes unity. This indicates that electron irradiation of FEP film with energies lower than 2.7 keV induces positive charging. From the charge decay characteristics after electron irradiation, the volume resistivity of the film was also obtained as a function of the electric fields in the bulk of the FEP film. 相似文献
992.
Thankaraj Salammal Shabi Souren Grigorian Martin Brinkmann Ullrich Pietsch Nils Koenen Navaphun Kayunkid Ullrich Scherf 《应用聚合物科学杂志》2012,125(3):2335-2341
Low-temperature casting of high molecular weight (HMW > 40 kDa) regioregular poly(3-hexylthiophene) (P3HT) is demonstrated to yield highly crystalline P3HT thin films with well defined and preferentially edge-on oriented [(100) contact plane] nanocrystallites on the pure and silanized Si/SiO2 substrates. Transmission electron microscopy and X-ray diffraction provide evidence for the increase in preferential edge-on orientation of P3HT-conjugated backbone while decreasing the film preparation temperature below room temperature. The optimum growth temperature is about −12°C for the given concentration (2 mg/mL in CHCl3). The reduced evaporation rate of the solvent results in a better selection of the thermodynamically stable orientation of nanocrystallites onto the substrate. The degree of preferential orientation and size of the crystallites can be further increased on n-octadecyltrichlorosilane-treated SiO2 substrates as well as by annealing the films at 200°C for 1 h. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
993.
Here, we report on the performance and the characterization of all solution-processable top-contact organic thin-film transistors (OTFTs) consisting of a natural-resourced triacetate cellulose gate dielectric and a representative hole-transport poly[2,5-bis(3-dodecylthiophen-2-yl)thieno[3,2-b]thiophene] (pBTTT) semiconductor layer on rigid or flexible substrates. The bio-based triacetate cellulose layer has an important role in the OTFT fabrication because it provides the pBTTT semiconducting polymer with highly suitable gate dielectric properties including a low surface roughness, hydrophobic surface, appropriate dielectric constant, and low leakage current. The triacetate cellulose gate dielectric-based pBTTT OTFTs exhibit an average filed-effect mobility of 0.031 cm2/Vs similar to that obtained from a SiO2 gate dielectric-based OTFT device in ambient conditions. Even after a bending stimulation of 100 times and in an outward bending state, the flexible triacetate cellulose gate pBTTT OTFT device still showed excellent electrical device performance without any hysteresis. 相似文献
994.
Annalisa Lucera Amalia Conte Matteo Alessandro Del Nobile 《International Journal of Food Science & Technology》2012,47(8):1598-1604
In this work, the influence of packaging mass transport properties on quality loss of fresh‐cut cauliflower mixtures was addressed. The study was organised in two subsequent experimental steps; first, the selection of micro‐perforated packaging films was carried out by monitoring the package headspace gas concentrations of fresh‐cut white, green cauliflower and roman cabbage. Then, the effects of the barrier properties of the selected micro‐perforated film on shelf life of two different fresh‐cut cauliflower mixtures, stored at 4 ± 1 °C, were addressed. Results suggested that, among the investigated films, the micro‐perforated polymeric matrix with the lowest oxygen transmission rate value showed the best performance as it created the optimum headspace gas composition for each cauliflower variety, as well as, for the product mixtures. The appearance of visible moulds was the factor limiting product shelf life that accounted for about 18 days for both the investigated cauliflower mixtures. 相似文献
995.
The hot tearing susceptibility of MgZn_(4.5)Y_xZr_(0.5)(x = 0.5, 1, 2, 4, 6) alloys was evaluated using ClyneDavies' theoretical model and a constrained rod casting(CRC) apparatus equipped with a load cell and data acquisition system. The results obtained from these two approaches were in good agreement, illustrating that the hot tearing susceptibility of the investigated alloys is in the order of MgZn_(4.5)Y_xZr_(0.5) MgZn_(4.5)Y_xZr_(0.5) MgZn_(4.5)Y_xZr_(0.5) MgZn_(4.5)Y_xZr_(0.5) MgZn_(4.5)Y_xZr_(0.5). The microstructure and morphology of hot tearing regions were observed by means of X-ray diffraction and scanning electron microscopy. The function curves on variation of contraction force and temperature versus time were recorded by a computer during solidification of the MgZn_(4.5)Y_xZr_(0.5) alloys in a "T" type mold after A/D(Analog to digital) conversion. Results show that both the amount and morphology of the second phases have a great relationship with the hot tearing susceptibility. But the former plays a more important role on that of MgZn_(4.5)Y_xZr_(0.5) alloys. The role of low-melting point eutectic phases on the hot tearing susceptibility of MgZn_(4.5)Y_xZr_(0.5) alloys changes gradually with different Y contents. When Y ≤ 1wt.%, it is mainly a damaging effect on intergranular bonding force; when Y 1wt.%, it is mainly an intergranular feeding effect on formed separated dendrites. 相似文献
996.
Anshu Tyagi Florian Döring Hans-Ulrich Krebs Astrid Pundt 《International Journal of Hydrogen Energy》2017,42(35):22575-22582
The influence of a thin polycarbonate de-adhesion layer on the hydrogen concentration is studied on 30 nm vanadium films deposited on glass substrates, using electrochemical hydrogenography in an optical microscopy and scanning tunneling microscopy. It is shown that the optical reflection provides information about the de-adhesion morphology (buckles) while the optical transmission signal gives information about concentration and film thickness changes. Artificially patterned samples allow simultaneous studying adhered and de-adhered film parts, for similar mean concentrations. The optical data clearly show a different hydrogen behavior of the two parts. Data interpretation suggests higher local hydrogen content in the adhered film parts than for the detached films parts. Strong changes in the optical transmission of the adhered film parts can be attributed to strong morphological changes at the film surface. These changes are mainly attributed to grain sliding processes in the vanadium film. 相似文献
997.
Nanocrystalline Bi2S3 thin films are deposited on tin chloride treated glass substrate from the solution containing bismuth nitrate, triethanolamine (TEA) and thioacetamide (TAM) at a bath temperature 318 K. The prepared films are subsequently annealed at different temperatures for studying the effect of thermal treatment on the structural, surface morphology, optical and electrical properties of the films. The X-ray diffraction studies affirmed that the deposited films are orthorhombic structures with average crystallites size of 14 nm to 28 nm. The scanning electron microscopy (SEM) images revealed that the films comprise of grains of spherical shape of unequal size. It is also observed that the small particles aggregate together to form a larger cluster. The average grain sizes determined from the TEM images are smaller than the crystallites size obtained from the XRD studies. The optical band gap of the films has been estimated to be 2.24–2.05 eV for the as-prepared and annealed films, respectively. The electrical conductivity of the as prepared Bi2S3 films at room temperature is found to be in the order of 10−3 Ω−1 m−1. 相似文献
998.
999.
本文结合平潭某建筑场地真空预压地基处理密封膜下真空压力不足的工程实例,通过分析真空压力过低的原因,供有关工程参考。 相似文献
1000.
简要介绍BOPS国产化原料在环保绿色窗口膜生产中的应用与实施,阐述聚苯乙烯(BOPS)料粒在薄膜生产中使用的特点,以及其良好的发展前景,重点论述该产品生产过程中的关键技术。 相似文献