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991.
Junshi Soeda Toshihiro Okamoto Azusa Hamaguchi Yoshinori Ikeda Hiroyasu Sato Akihito Yamano Jun Takeya 《Organic Electronics》2013,14(4):1211-1217
We report a novel solution-crystallization method to grow two-dimensional platelet-shaped single-crystals of well-known insoluble organic semiconductors via thermal conversion of their precursor molecules dissolved in ionic liquids (ILs). By optimizing conditions of the crystal growth regarding physical properties of ILs such as density and viscosity, we successfully and reproducibly obtained thin platelets of pentacene and dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT) single-crystals, with which nearly the best performing field-effect transistors are constructed for the two compounds. The prompt and simple technique has opened the way to use practically insoluble organic semiconductor materials for high-performance printed electronics, which enables mass-producible and large-area organic circuitry devices. 相似文献
992.
Y. Naoi Y. Kawakami T. Nakanishi Y. Lacroix Y. Shintani S. Sakai 《Materials Science in Semiconductor Processing》2001,4(6)
We investigated GaN films etched by using reactive ion etching (RIE) technique to fabricate the GaN-based devices. The samples were grown on sapphire substrate by metal organic chemical vapor deposition (MOCVD), and Ti/Al contacts were formed on n-GaN surfaces after etching processes. The effects of the kinds of reactive gases were evaluated by secondary ion mass spectrometry (SIMS). The results showed that in the sample etched using BCl3 gas, the signal from boron contaminations was strongly detected at the interface between the contact metal and n-GaN, and we found that additional etching in Cl2 plasma after etching with BCl3 gas was essential to make a good contact. 相似文献
993.
Tatsuyuki Makita Ryohei Nakamura Mari Sasaki Shohei Kumagai Toshihiro Okamoto Shun Watanabe Jun Takeya 《Advanced functional materials》2020,30(39)
Deposition of metallic electrodes on a semiconductor medium is an indispensable factor in governing carrier injection, and a metal/semiconductor contact that can be formed via solution process is highly desired in printed electronics. However, fine‐patterning the solution processes of metallic electrodes without damaging the excellent electronic properties of organic semiconductors (OSCs) is still a challenge. In this work, electroless plating, a metal coating technique that involves auto‐catalytic reaction in an aqueous solution, is used to fabricate top‐contact organic thin‐film transistors (OTFTs). An electroless‐plated gold pattern with a spatial resolution of 10 micrometers is transferred and laminated on a monolayer of OSCs to serve as a hole‐injection electrode. The fabricated OTFTs exhibit reasonably high field‐effect mobility of up to 13 cm2 V?1 s?1 and decent contact resistance as low as 120 Ω · cm, which implies that an ideal metal/semiconductor contact can be realized. This electroless plating technique can provide possibilities for practical mass production of organic integrated circuits because it is in principle cost‐effective, capable of covering large areas, high‐vacuum free, and environmentally friendly. 相似文献
994.
Limits on the accuracy of 3-D thickness measurement in magnetic resonance images--effects of voxel anisotropy 总被引:3,自引:0,他引:3
Sato Y Tanaka H Nishii T Nakanishi K Sugano N Kubota T Nakamura H Yoshikawa H Ochi T Tamura S 《IEEE transactions on medical imaging》2003,22(9):1076-1088
Measuring the thickness of sheet-like thin anatomical structures, such as articular cartilage and brain cortex, in three-dimensional (3-D) magnetic resonance (MR) images is an important diagnostic procedure. This paper investigates the fundamental limits on the accuracy of thickness determination in MR images. We defined thickness here as the distance between the two sides of boundaries measured at the subvoxel resolution, which are the zero-crossings of the second directional derivatives combined with Gaussian blurring along the normal directions of the sheet surface. Based on MR imaging and computer postprocessing parameters, characteristics for the accuracy of thickness determination were derived by a theoretical simulation. We especially focused on the effects of voxel anisotropy in MR imaging with variable orientation of sheet-like structure. Improved and stable accuracy features were observed when the standard deviation of Gaussian blurring combined with thickness determination processes was around square root of 2/2 times as large as the pixel size. The relation between voxel anisotropy in MR imaging and the range of sheet normal orientation within which acceptable accuracy is attainable was also clarified, based on the dependences of voxel anisotropy and the sheet normal orientation obtained by numerical simulations. Finally, in vitro experiments were conducted using an acrylic plate phantom and a resected femoral head to validate the results of theoretical simulation. The simulated thickness was demonstrated to be well-correlated with the actual in vitro thickness. 相似文献
995.
Hidetoshi Nakanishi Akira Ito Kazuhisa Takayama Iwao Kawayama Hironaru Murakami Masayoshi Tonouchi 《Journal of Infrared, Millimeter and Terahertz Waves》2016,37(5):498-506
We observed photoexcited carrier responses in solar cells excited by femtosecond laser pulses with spatial and temporal resolution using an optical pump-terahertz emission probe technique. We visualized the ultrafast local variation of the intensity of terahertz emission from a polycrystalline silicon solar cell using this technique and clearly observed the change in signals between a grain boundary and the inside of a grain in the solar cell. Further, the time evolution of the pump–probe signals of the polycrystalline and monocrystalline silicon solar cells was observed, and the relaxation times of photoexcited carriers in the emitter layers of crystalline silicon solar cells were estimated using this technique. The estimated relaxation time was consistent with the lifetime of the Auger recombination process that was dominant in heavily doped silicon used as an emitter layer for the silicon solar cells, which is difficult to obtain with photoluminescence method commonly used for the evaluation of solar cells. 相似文献
996.
含硫氨基酸是所有生物生长繁殖不可缺少的氨基酸。尽管毕赤酵母在工业发酵中作为重要的表达菌株,但是其含硫氨基酸的生物合成途径尚未明了。作者采用生物信息学及表型分析的方法,阐明了毕赤酵母含硫氨基酸的生物合成途径。结果表明,毕赤酵母可通过O-乙酰同丝氨酸及O-乙酰丝氨酸与无机硫元素合成含硫氨基酸,甲硫氨酸与半胱氨酸也可通过转硫途径实现相互转化。另外毕赤酵母cys3Δ突变菌株在未添加半胱氨酸的合成培养基中对硒代甲硫氨酸表现出显著的抗性。综上所述,未来有望应用毕赤酵母表达硒蛋白用于蛋白质三级结构的分析。 相似文献
997.
Kozo Shimizu Teru Nakanishi Kazuaki Karasawa Kaoru Hashimoto Koichi Niwa 《Journal of Electronic Materials》1995,24(1):39-45
Recent high-density very large scale integrated (VLSI) interconnections in multichip modules require high-reliability solder
interconnection to enable us to achieve small interconnect size andlarge number of input/output terminals, and to minimize
soft errors in VLSIs induced by α-particle emission from solder. Lead-free solders such as indium (In)-alloy solders are a
possible alternative to conventional lead-tin (Pb-Sn) solders. To realize reliable interconnections using In-alloy solders,
fatigue behavior, finite element method (FEM) simulations, and dissolution and reaction between solder and metallization were
studied with flip-chip interconnection models. We measured the fatigue life of solder joints and the mechanical properties
of solders, and compared the results with a computer simulation based on the FEM. Indium-alloy solders have better mechanical
properties for solder joints, and their flip-chip interconnection models showed a longer fatigue life than that of Pb-Sn solder
in thermal shock tests between liquid nitrogen and room temperatures. The fatigue characteristics obtained by experiment agree
with that given by FEM analysis. Dissolution tests show that Pt film is resistant to dissolution into In solder, indicating
that Pt is an adequate barrier layer material for In solder. This test also shows that Au dissolution into the In-Sn solder
raises its melting point; however, Ag addition to In-Sn solder prevents melting point rise. Experimental results show that
In-alloy solders are suitable for fabricating reliable interconnections. 相似文献
998.
999.
Hisahiro Hagiwara Toshihiro Kuroda Takashi Hoshi Toshio Suzuki 《Advanced Synthesis \u0026amp; Catalysis》2010,352(5):909-916
MacMillan’s imidazolidinone catalyst was immobilized as a supported ionic liquid catalyst (Mac‐SILC) in the pores of silica gel with the aid of an ionic liquid – 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide. The heterogenized organocatalyst was utilized for the enantioselective Diels–Alder reaction of cyclopentadiene and cinnamaldehyde, recovered by simple filtration and subsequent evacuation, and repeatedly used up to six times in 81% average chemical yield, 87% ee for endo‐ and 80% ee for exo‐products. The Mac‐SILC was effective for a variety of substrates. 相似文献
1000.
Akira Nakajima Tomoki Kobayashi Toshihiro Isobe Sachiko Matsushita 《Materials Letters》2011,65(19-20):3051-3054
Porous spherical CeO2 particles were prepared by impregnation of a cerium precursor solution into organic monolith sphere particles, with subsequent firing at 500 °C in air. The single-phase CeO2 powder had specific surface area of greater than 140 m2/g. Photodeposition with UV illumination loaded Au onto the CeO2 particle surface, which changed from yellowish to purple because of localized surface plasmon resonance (LSPR). The Au-loading increased photocatalytic decomposition activity of the CeO2 powder for gaseous 2-propanol (IPA) under visible light. Thermal desorption of IPA, which was adsorbed to all porous spheres, provided flux to the photocatalytic reaction field of the sphere outer surface. 相似文献