全文获取类型
收费全文 | 332篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 14篇 |
化学工业 | 83篇 |
金属工艺 | 16篇 |
机械仪表 | 16篇 |
建筑科学 | 2篇 |
能源动力 | 6篇 |
轻工业 | 18篇 |
无线电 | 44篇 |
一般工业技术 | 67篇 |
冶金工业 | 57篇 |
原子能技术 | 4篇 |
自动化技术 | 8篇 |
出版年
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2016年 | 4篇 |
2015年 | 5篇 |
2014年 | 5篇 |
2013年 | 17篇 |
2012年 | 7篇 |
2011年 | 15篇 |
2010年 | 14篇 |
2009年 | 9篇 |
2008年 | 7篇 |
2007年 | 7篇 |
2006年 | 17篇 |
2005年 | 6篇 |
2004年 | 10篇 |
2003年 | 8篇 |
2002年 | 9篇 |
2001年 | 7篇 |
2000年 | 6篇 |
1999年 | 11篇 |
1998年 | 24篇 |
1997年 | 11篇 |
1996年 | 17篇 |
1995年 | 7篇 |
1994年 | 6篇 |
1993年 | 10篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 6篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 12篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1967年 | 1篇 |
1932年 | 2篇 |
排序方式: 共有335条查询结果,搜索用时 15 毫秒
91.
Stress corrosion cracking tests of an aged Cu?4% Ti alloy in various copper-ammonia solutions revealed that the alloy was highly susceptible to stress corrosion cracking in highly alkaline solutions with preconcentrated copper, but almost immune in Mattsson solutions (pH 3.9–10.0). The surface film (Cu2O) may be not an important factor in stress corrosion cracking in this alloy system. Increase in preconcentrated copper content and ammonia concentration leads to a decrease in the time to failure. Preconcentrated copper enhances the stress corrosion susceptibility by promoting preferential dissolution of copper through acceleration of the cathodic reaction. In the highly susceptible solutions, the corrosion process seems to be mainly controlled by diffusion of cupric complex ions and the preferential corrosion of copper under concentration polarization. 相似文献
92.
93.
Surface polyion complex (sPIC) gels were prepared with a nonionic hydrogel interior core, composed of poly(N‐vinylformamide and poly(N‐vinylacetamide), and a chemically bounded polyion complex layer on the outer surface, composed of poly(vinylamine) and poly(acrylic acid). The gels were investigated as controlled drug release models based on electrostatic interactions depending on pH. Methylene blue and allura red were employed as cationic and anionic drug models, respectively, and resulted in the selective adsorption depending on pH conditions. Monovalent and multivalent anionic drug models, allura red and 1,3,6‐naphthalenetrisulfonate were observed for their releasing behavior from the sPIC gel. The results indicated that the multivalent anionic drug effectively controlled release depending on pH conditions. We further investigated sPIC gels regarding their ability to control the release of ionic molecules as a function of pH‐driven changes in electrostatic interactions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42081. 相似文献
94.
Kandy Napan Dr. Shuwei Zhang Whitney Morgan Thomas Anderson Prof. Dr. Jon Y. Takemoto Prof. Dr. Jixun Zhan 《Chembiochem : a European journal of chemical biology》2014,15(15):2289-2296
Three key tailoring enzymes in pradimicin biosynthesis: PdmJ, PdmW, and PdmN, were investigated. PdmW was characterized as the C‐6 hydroxylase by structural characterization of the corresponding product, 6‐hydroxy‐G‐2A. The efficiencies of the C‐5 and C‐6 hydroxylations, catalyzed respectively by PdmJ and PdmW, were low when they were expressed individually with the early biosynthetic enzymes that form G‐2A. When these two cytochrome P450 enzymes were co‐expressed, a dihydroxylated product, 5,6‐dihydroxy‐G‐2A, was efficiently produced, indicating that these two enzymes work synergistically in pradimicin biosynthesis. Heterologously expressed PdmN in Streptomyces coelicolor CH999 converted G‐2A to JX137a by ligating a unit of D ‐alanine to the carboxyl group. PdmN has relaxed substrate specificity toward both amino acid donors and acceptors. Through combinatorial biosynthesis, a series of new pradimicin analogues were produced. 相似文献
95.
Toshiyuki Kawai Mitsuru Takemoto Shunsuke Fujibayashi Masashi Neo Haruhiko Akiyama Seiji Yamaguchi Deepak K. Pattanayak Tomiharu Matsushita Takashi Nakamura Tadashi Kokubo 《Journal of materials science. Materials in medicine》2012,23(12):2981-2992
The effects of surface treatment on the bone-bonding properties of Ti metal were examined by both mechanical detaching test and histological observation after implantation into rabbit tibiae for various periods ranging from?4 to?26?weeks. The bone-bonding ability of Ti metal, which is extremely low as it is abraded, was hardly increased by simple heat treatment at 600?°C or treatment with H2SO4/HCl mixed acid alone, but was markedly increased by the heat treatment after the acid treatment. Even Ti metal that had been previously subjected to NaOH treatment showed considerably high bone-bonding ability after acid and heat treatments. Such high bonding abilities were attributed to their high apatite-forming ability in the body environment. Their high apatite-forming abilities were attributed to a high positive surface charge, and not to the type of crystalline phase or specific roughness of their surfaces. The present study has demonstrated that acid and subsequent heat treatments are effective for conferring stable fixation properties on Ti metal implants. 相似文献
96.
Hiroshi Hirano Takuto Okada Yoshinobu Nakamura Joji Kadota Seiji Watase Kiichi Hasegawa 《大分子材料与工程》2006,291(3):205-209
Summary: Epoxy resins are widely used in electronics and electric industries because of their superior properties. In recent years, excellent bonding properties for metals (e.g., copper, gold, aluminium, silver, etc.), to which it is hard to adhere, have become desirable for epoxy resins in the electric and electronics industrial fields. However, epoxy resins have only poor bonding strength to the metals. In order to increase the heterojunction strength between epoxy resins and copper, the introduction of sulfur, providing strong interactions with metals, was investigated. TDP polyester and MPS polythioesters containing sulfur moieties were employed as the sulfur‐containing modifiers for the epoxy resin. Epoxy resins containing a modifier (5–20 phr) and a curing agent were cured between copper plates at 120 °C for 2 h and at 170 °C for 2 h. The effect of the added modifiers was evaluated by the lap‐shear testing method. It could be demonstrated that MPS polythioesters have a beneficial effect on the enhancement of the epoxy resin/copper heterojunction. The most effective example was the addition of 20 phr of the MPS_7 polythioester, which increased the lap shear strength from 5.7 to 17 MPa.
97.
Significance of saturated clays seams for the stability of rainfall-induced landslides 总被引:2,自引:0,他引:2
Hideki Ohta Thirapong Pipatpongsa Sokbil Heng Seiya Yokota Masaru Takemoto 《Bulletin of Engineering Geology and the Environment》2010,69(1):71-87
This paper reviews the analyses of several slope failures in Japan associated with clay seams and assesses the significance
of ground water level. Constant-volume shear box tests were used to obtain the strength parameters. The research considered
the significance of capillary forces in the clay mass in the development of a laboratory-established cohesion. It was concluded
that the laboratory-obtained apparent cohesion may not be applicable in actual site conditions and that a more realistic value
can be obtained using submerged/saturated samples in the constant-volume direct shear test. The practical implications of
this are demonstrated with a review of the Guinsaugon rockslide, South Leyte, Philippines. 相似文献
98.
Takekazu Ishida Kiichi Okuda Hidehito Asaoka 《Journal of Low Temperature Physics》1999,117(5-6):1387-1391
Vortex lattice melting in the Hc configuration of an YBa
2
Cu
3
O
6.94
single crystal has been investigated by means of the ac susceptibility – i and the magnetic torque . The melting transition of vortex lattice occurs in Hc, too. Since the torque curve shows a sharp peak in the irreversible torque at
c
90° due to intrinsic pinning at lower temperatures, we can determine the irreversibility line for the intrinsic pinning. The melting transition in the Hc configuration appears at temperatures where the intrinsic-pinning peak is absent. We consider that the intrinsic pinning does not affect the nature of the vortex melting transition in the Hc configuration. 相似文献
99.
We developed a microsystem for cell experiments consisting of a scanning thermal lens microscope detection system and a cell culture microchip. The microchip system was good for liquid control in microspace, and this results in secure cell stimulation and coincident in vivo observation of the cell responses. The system could detect nonfluorescent biological substances with extremely high sensitivity without any labeling materials and had a high spatial resolution of approximately 1 microm. This system was applied to monitoring of cytochrome c distribution in a neuroblastoma-glioma hybrid cell cultured in the microflask (1 mm x 10 mm x 0.1 mm; 1 microL) fabricated in a glass microchip. Cytochrome c release from mitochondria to cytosol during the apoptosis process was successfully monitored with this system. The cytochrome c detected with this system was estimated to be approximately 10 zmol. We concluded that the system was suitable for measuring the distribution of chemical substances in a single cell because the microchip is good for liquid handling in microspace and the thermal lens microscope has high sensitivity and spatial resolution. 相似文献
100.
Continuous-flow chemical processing on a microchip by combining microunit operations and a multiphase flow network 总被引:1,自引:0,他引:1
Tokeshi M Minagawa T Uchiyama K Hibara A Sato K Hisamoto H Kitamori T 《Analytical chemistry》2002,74(7):1565-1571
A new design and construction methodology for integration of complicated chemical processing on a microchip was proposed. This methodology, continuous-flow chemical processing (CFCP), is based on a combination of microunit operations (MUOs) and a multiphase flow network. Chemical operations in microchannels, such as mixing, reaction, and extraction, were classified into several MUOs. The complete procedure for Co(II) wet analysis, including a chelating reaction, solvent extraction, and purification was decomposed into MUOs and reconstructed as CFCP on a microchip. Chemical reaction and molecular transport were realized in and between continuous liquid flows in a multiphase flow network, such as aqueous/aqueous, aqueous/organic, and aqueous/organic/aqueous flows. When the determination of Co(II) in an admixture of Cu(II) was carried out using this methodology, the determination limit (2sigma) was obtained as 18 nM, and the absolute amount of Co chelates detected was 0.13 zmol, that is, 78 chelates. The sample analysis time was faster than that of a conventional processing system. Moreover, troublesome operations such as phase separation and acid and alkali washing, all necessary for the conventional system, were simplified. The CFCP methodology proposed here can be applied to various on-chip applications. 相似文献