全文获取类型
收费全文 | 1166篇 |
免费 | 23篇 |
专业分类
电工技术 | 39篇 |
化学工业 | 252篇 |
金属工艺 | 28篇 |
机械仪表 | 33篇 |
建筑科学 | 21篇 |
矿业工程 | 2篇 |
能源动力 | 25篇 |
轻工业 | 108篇 |
水利工程 | 5篇 |
无线电 | 118篇 |
一般工业技术 | 204篇 |
冶金工业 | 219篇 |
原子能技术 | 31篇 |
自动化技术 | 104篇 |
出版年
2023年 | 4篇 |
2022年 | 17篇 |
2021年 | 20篇 |
2020年 | 7篇 |
2019年 | 16篇 |
2018年 | 24篇 |
2017年 | 21篇 |
2016年 | 34篇 |
2015年 | 9篇 |
2014年 | 30篇 |
2013年 | 68篇 |
2012年 | 49篇 |
2011年 | 61篇 |
2010年 | 50篇 |
2009年 | 46篇 |
2008年 | 70篇 |
2007年 | 51篇 |
2006年 | 43篇 |
2005年 | 31篇 |
2004年 | 23篇 |
2003年 | 25篇 |
2002年 | 16篇 |
2001年 | 18篇 |
2000年 | 21篇 |
1999年 | 21篇 |
1998年 | 85篇 |
1997年 | 58篇 |
1996年 | 46篇 |
1995年 | 29篇 |
1994年 | 15篇 |
1993年 | 24篇 |
1992年 | 10篇 |
1991年 | 10篇 |
1990年 | 6篇 |
1989年 | 10篇 |
1988年 | 7篇 |
1987年 | 10篇 |
1986年 | 11篇 |
1985年 | 9篇 |
1984年 | 12篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1978年 | 9篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1974年 | 6篇 |
1972年 | 3篇 |
排序方式: 共有1189条查询结果,搜索用时 15 毫秒
51.
52.
Relationships between the morphologies and mechanical properties of binary blends of a photocurable polymer (2‐propenoic acid, (octahydro‐4,7‐methano‐1H‐indenediyl) bis(methylene)ester; DCA) and a linear polymer (poly(4,4′‐cyclohexylidene bisphenol carbonate); PCz) have been investigated. The blend films are prepared by in situ photopolymerization of homogeneous mixtures of a DCA‐monomer and PCz. The phase structure has been converted from a semi‐interpenetrating polymer networks (semi‐IPN) structure to a bicontinuous structure by controlling the cure temperature. Bicontinuous phase‐separated structures can be obtained by curing a wide range of compositions of 17–50 wt.‐% PCz at high temperatures. Miscible semi‐IPN structures are attained by means of photopolymerization below the glass transition temperature of the homogenous mixture before performing photoirradiation, such that magnetic relaxation measurements showed the blend to be miscible in the 10 nm order. The tensile strength and modulus reached a maximum in those blends having an intermediate vague phase structure between semi‐IPN and bicontinuous structures that have a strong interfacial interaction, which leads to incomplete phase decomposition in the PCz‐rich matrix phase. The maximum strength and modulus prepared under optimum condition are inferior to those of the individual components. In contrast, the elongation and break energy are greatly improved in those blends with bicontinuous structures having a diffused phase boundary.
53.
Takanori Kondo Chihiro Yasui Dr. Taisuke Banno Prof. Dr. Kouichi Asakura Dr. Tokuma Fukuoka Dr. Kazunori Ushimaru Dr. Maito Koga Dr. Hiroyuki Minamikawa Dr. Azusa Saika Dr. Tomotake Morita Prof. Dr. Daisuke Takahashi Prof. Dr. Kazunobu Toshima 《Chembiochem : a European journal of chemical biology》2022,23(2):e202100631
Mannosylerythritol lipids (MELs), which are one of the representative sugar-based biosurfactants (BSs) produced by microorganisms, have attracted much attention in various fields in the sustainable development goals (SDGs) era. However, they are inseparable mixtures with respect to the chain length of the fatty acids. In this study, self-assembling properties and structure-activity relationship (SAR) studies of recovery effects on damaged skin cells using chemically synthesized MELs were investigated. It was revealed, for the first time, that synthetic and homogeneous MELs exhibited significant self-assembling properties to form droplets or giant vesicles. In addition, a small difference in the length of the fatty acid chains of the MELs significantly affected their recovery effects on the damaged skin cells. MELs with medium or longer length alkyl chains exhibited much higher recovery effects than that of C18-ceramide NP. 相似文献
54.
Ryuta Shigefuku Hideaki Takahashi Hiroyasu Nakano Tsunamasa Watanabe Kotaro Matsunaga Nobuyuki Matsumoto Masaki Kato Ryo Morita Yousuke Michikawa Tomohiro Tamura Tetsuya Hiraishi Nobuhiro Hattori Yohei Noguchi Kazunari Nakahara Hiroki Ikeda Toshiya Ishii Chiaki Okuse Shigeru Sase Fumio Itoh Michihiro Suzuki 《International journal of molecular sciences》2016,17(9)
The progression of chronic liver disease differs by etiology. The aim of this study was to elucidate the difference in disease progression between chronic hepatitis C (CHC) and nonalcoholic fatty liver disease (NAFLD) by means of fibrosis markers, liver function, and hepatic tissue blood flow (TBF). Xenon computed tomography (Xe-CT) was performed in 139 patients with NAFLD and 152 patients with CHC (including liver cirrhosis (LC)). The cutoff values for fibrosis markers were compared between NAFLD and CHC, and correlations between hepatic TBF and liver function tests were examined at each fibrosis stage. The cutoff values for detection of the advanced fibrosis stage were lower in NAFLD than in CHC. Although portal venous TBF (PVTBF) correlated with liver function tests, PVTBF in initial LC caused by nonalcoholic steatohepatitis (NASH-LC) was significantly lower than that in hepatitis C virus (C-LC) (p = 0.014). Conversely, the liver function tests in NASH-LC were higher than those in C-LC (p < 0.05). It is important to recognize the difference between NAFLD and CHC. We concluded that changes in hepatic blood flow occurred during the earliest stage of hepatic fibrosis in patients with NAFLD; therefore, patients with NAFLD need to be followed carefully. 相似文献
55.
Chemical Removal of CeO2 Segregated on the Surface of CeO2–ZrO2 Binary Oxides for Improvement of OSC
Noriyoshi Kakuta Youko Sugino Hironobu Rachi Hironobu Ohkita Takanori Mizushima 《Topics in Catalysis》2009,52(13-20):1888-1892
A chemical treatment to remove residual CeO2 phase on CeO2–ZrO2 (CZ) solid solution was carried out. A CZ was treated by H2O2 for the reduction of Ce4+ to Ce3+ and then HNO3 for the dissolution of Ce3+ compounds (H–CZ). H2-TPR, TEM-EDX and XPS analyses revealed the removal of CeO2 phase and the homogeneous distribution of Ce species. About 20% improvement in oxygen storage capacity (OSC) of H–CZ was confirmed at 773 K by the weight measurements under H2/N2 and air atmospheres, indicating that the HNO3/H2O2 treatment was effective to avoid the deterioration of the OSC by segregated CeO2 on the CZ binary oxides. 相似文献
56.
R. Baskaran S. Selvasekarapandian N. Kuwata Yoshiki Iwai J. Kawamura T. Hattori 《应用聚合物科学杂志》2008,110(4):1945-1954
The lithium‐ion conducting gel polymer electrolytes (GPE), PVAc‐DMF‐LiClO4 of various compositions have been prepared by solution casting technique. 1H NMR results reveal the existence of DMF in the gel polymer electrolytes at ambient temperature. Structure and surface morphology characterization have been studied by X‐ray diffraction analysis (XRD) and scanning electron microscopy (SEM) measurements. Thermal and conductivity behavior of polymer‐ and plasticizer‐salt complexes have been studied by differential scanning calorimetry (DSC), TG/DTA, and impedance spectroscopy results. XRD and SEM analyses indicate the amorphous nature of the gel polymer‐salt complex. DSC measurements show a decrease in Tg with the increase in DMF concentrations. The thermal stability of the PVAc : DMF : LiClO4 gel polymer electrolytes has been found to be in the range of (30–60°C). The dc conductivity of gel polymer electrolytes, obtained from impedance spectra, has been found to vary between 7.6 × 10?7 and 4.1 × 10?4 S cm?1 at 303 K depending on the concentration of DMF (10–20 wt %) in the polymer electrolytes. The temperature dependence of conductivity of the polymer electrolyte complexes appears to obey the VTF behavior. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
57.
Sun-Chan Jeong Ichiro Katayama Hirokane Kawakami Yutaka Watanabe Hironobu Ishiyama Nobuaki Imai Yoshikazu Hirayama Hiroari Miyatake Masao Sataka Satoru Okayasu Hiroyuki Sugai Shin-Ichi Ichikawa Katsuhisa Nishio Shinichi Mitsuoka Takamitsu Nakanoya Masahito Yahagi Takanori Hashimoto Kazunori Takada Mamoru Watanabe Tomoko Ishikawa Akihiro Iwase 《Journal of Phase Equilibria and Diffusion》2005,26(5):472-476
For the effective use of short-lived radioactive beams, soon to be available at the Tokai Radioactive Ion Accelerator Complex, the authors have developed a radiotracer method for diffusion studies in solids. The experimental test was performed by the measurement of the diffusion coefficients of Li in a sample of the compound βLiAl using an α-emitting radiotracer of 8Li (T1/2=0.84 s). It was found that the time-dependent yields of the α particles from the diffusing 8Li that was initially implanted in the sample could be used as a measure of the diffusivity of the tracer in a nondestructive way. The method was applied to measure the self-diffusion coefficients of Li in βLiGa, and for investigating how the Li diffusion in the Li ionic conductors is affected by the concentration of atomic defects (i.e., the existence of the atomic vacancies of Li and the defects in Ga sites that are replaced by Li). 相似文献
58.
Development of new-concept desk top size machine tool 总被引:6,自引:0,他引:6
A desktop multiprocess machinery has been designed that has two concepts: miniaturizing of machine tool and multiprocessing with a same machine tool. The prototype of desktop multiprocess machinery is developed in this study. This is tabletop size machine tool that has five changeable machining heads. Outline of main body and machining head are presented.In order to know the basic accuracy of desktop multiprocess machinery, experimental evaluation is carried out. Machining head setting error, stiffness of multiprocess machinery and straightness of X, Y, Z stage is measured. To study the basic performance of desktop multiprocess machinery, a complex machining experiment is carried out with the developed machine tool. The complex machining consists of three steps: electrode machining by milling, hole shaping by EDM, and hole finishing by ECM. These steps are performed in sequence on the same machine tool. The complex machining is successfully carried out. In order to evaluate the desktop multiprocess machinery from environmental point of view, machining energy, volume of machining liquid, and installation space of desktop multiprocess machinery are measured. The measured values are compared with estimated values with conventional machine tools. The machining energy, the volume of machining liquid, and the installation space of desktop multiprocess machinery are smaller than those of conventional machine tool. 相似文献
59.
Yumi Fukuda Koichi Harada Maki Yonetsu Ariane K. Albessard Yasushi Hattori Kenji Essaki Yasuhiro Goto Tomohiro Suetsuna 《Journal of the American Ceramic Society》2021,104(12):6563-6571
When reaction-bonded silicon nitride containing MgO/Y2O3 additives is sintered at three different temperatures to form sintered reaction-bonded silicon nitride (SRBSN), the thermal conductivity increases with sintering temperature. The β-Si3N4 (silicon nitride) crystals of SRBSN ceramics were synthesized and characterized to investigate the relation between the crystal structure and the lattice oxygen content. The hot-gas extraction measurement result and the crystal structure obtained using Rietveld analysis suggested that the unit cell size of the β-Si3N4 crystal increases with the decrease in the lattice oxygen content. This result is reasonable considering that the lattice oxygen with the smaller covalent radius substitutes nitrogen with the larger one in the β-Si3N4 crystals. The lattice oxygen content decreased with increasing sintering temperature which also correlated with increase in thermal conductivity. Moreover, it is noteworthy from the viewpoint that it may be possible to apply the lattice constant analysis for the nondestructive and simple measurement of the lattice oxygen content that deteriorates the thermal conductivity of the β-Si3N4 ceramics. 相似文献
60.
Seiji Sasabe Tsuyoshi Matsumoto Tetsu Iwase Yasunori Hattori Tadaaki Miono 《Welding International》2013,27(4):273-280
Dissimilar metal joining of aluminium alloys to steel is generally difficult to be in practical use because of a formation of brittle intermetallic Fe–Al compound (IMC) at the interface of the joint. The authors have been researching in order to minimize the thickness of this brittle IMC in order to get excellent joint strength and have found that the formation of this brittle IMC is regionally prevented by using the advanced hot-dip aluminized steel sheet and by adopting suitable joining conditions. In particular, this paper focuses on the mechanism of creating this IMC-free region in the case of MIG-braze welding and the results obtained are as follows. (1) The creation of IMC-free region is initiated as the first process by the dissolution of the τ5 phase (Fe–Al–Si) in the aluminized layer into the weld metal, and temperatures of more than 886 K for dissolution during MIG-braze welding and the use of filler metal for dilution of Fe and Si in τ5 phase have significant effects. (2) In the second process, the diffusion between aluminium-alloy weld metal and base steel is restricted by AlN on the surface thin layer of the base steel which existed under 908 K temperature conditions during MIG-braze welding. 相似文献