全文获取类型
收费全文 | 277篇 |
免费 | 6篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 18篇 |
综合类 | 1篇 |
化学工业 | 73篇 |
金属工艺 | 4篇 |
建筑科学 | 21篇 |
能源动力 | 13篇 |
轻工业 | 15篇 |
水利工程 | 1篇 |
石油天然气 | 3篇 |
无线电 | 11篇 |
一般工业技术 | 69篇 |
冶金工业 | 27篇 |
原子能技术 | 4篇 |
自动化技术 | 34篇 |
出版年
2022年 | 5篇 |
2021年 | 3篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2017年 | 4篇 |
2015年 | 4篇 |
2014年 | 5篇 |
2013年 | 16篇 |
2012年 | 12篇 |
2011年 | 20篇 |
2010年 | 9篇 |
2009年 | 16篇 |
2008年 | 28篇 |
2007年 | 14篇 |
2006年 | 7篇 |
2005年 | 7篇 |
2004年 | 6篇 |
2003年 | 7篇 |
2002年 | 11篇 |
2001年 | 10篇 |
2000年 | 10篇 |
1999年 | 10篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 8篇 |
1980年 | 1篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1972年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有294条查询结果,搜索用时 593 毫秒
251.
Kikuchi T Okazaki M Kimura SD Motobayashi T Baasansuren J Hattori T Abe T 《Journal of hazardous materials》2008,154(1-3):294-299
The objective of this study is to assess the applicability of a commercial magnesium oxide (MgO) and a composite material containing MgO and natural minerals ('MgO-SH-A') as the soil amendments for suppression of cadmium (Cd) uptake and accumulation into rice grains. A cultivation experiment of rice plants (Oryza sativa L. cv. Kinuhikari) was conducted in an actual Cd-contaminated alluvial paddy field to evaluate the effectiveness of these materials. The 'plant available' fractions of Cd in the paddy soil significantly decreased by application of commercial MgO at 2250 kg ha(-1) or MgO-SH-A at 4500 kg ha(-1). These decreases would be primarily attributed to the increase in soil pH due to applications of the MgO materials because these soil Cd fractions were significantly negatively correlated with the soil pH. Even under a suppressive condition for Cd uptake by rice plants, i.e., continuous flooding of the paddy field around the heading stage, applications of these materials further reduced Cd concentration in brown rice as compared to that from the control. It was concluded that the two MgO materials examined would be effective in preventing Cd contamination of rice grains grown in Cd-polluted paddy fields. 相似文献
252.
Gopinath SC Awazu K Fujimaki M Sugimoto K Ohki Y Komatsubara T Tominaga J Gupta KC Kumar PK 《Analytical chemistry》2008,80(17):6602-6609
Evanescent-field-coupled (EFC) waveguide-mode sensors can be used to detect nucleic acids or proteins from the changes in the local index of refraction upon adsorption of the target molecule on a waveguide surface. We recently described an EFC waveguide-mode sensor in which nanometric holes on a waveguide film resulted in an improved sensitivity in the analysis of the interactions of biomolecules. In the present study, we have shown that sensitivity depends upon the diameter of the holes, where increase in diameter of holes increases spectral shift resulting in an improved sensitivity. Using this improved EFC waveguide-mode sensor, we could detect interactions between RNA and a small ligand, cyanocobalamin (vitamin B 12), and between RNA and a protein (human coagulation factor IXa). These two interactions were monitored on surfaces modified with biotin-streptavidin-biotin and N-(2-trifluoroethanesulfonatoethyl)- N-(methyl)triethoxysilylpropyl-3-amine, respectively. 相似文献
253.
Okazaki M Kimura SD Kikuchi T Igura M Hattori T Abe T 《Journal of hazardous materials》2008,154(1-3):287-293
The objective of this study is to assess the applicability of a commercial magnesium oxide (MgO) and a composite material containing MgO and natural minerals ('MgO-SH-A') as the soil amendments for suppression of cadmium (Cd) uptake and accumulation into rice grains. Firstly, the mineralogical and physicochemical properties, soil neutralizing capacities and Cd sorption characteristics of these materials were investigated. Both materials were strongly alkaline and possessed large surface areas. The X-ray diffraction pattern of MgO-SH-A indicated the presence of MgO and a magnesium-silicate mineral (antigorite) as the main components. MgO-SH-A showed a milder soil neutralizing capacity as compared to commercial MgO. The sorptions of Cd on commercial MgO and MgO-SH-A both fitted Langmuir isotherm. The maximum Cd sorption capacity of commercial MgO (46.8 mmol g(-1) DW) was higher than that of MgO-SH-A (5.87 mmol g(-1) DW), although the latter material showed higher affinity to Cd as compared to the former one. The dominant reaction involved in the Cd sorptions was suggested to be precipitation of Cd(OH)2 on the material surface. About 40% of Cd sorbed on MgO-SH-A was resistant to desorption by 0.1 M HCl, implying that this portion was strongly retained on the material surface. 相似文献
254.
Yoji Mine Jean-Marc Olive Koichi Nagata Tetsuro Mitsutani 《Materials Science and Engineering: A》2011,528(28):8090-8099
The effects of hydrogen with a concentration of ∼0.1 mass ppm on cyclic plasticity and crack growth were investigated on a Fe-0.01 mass% C alloy. In polycrystalline specimens, the grains covered with multiple gliding were decreased but those including discrete slip bands were increased in the presence of hydrogen. The hydrogen effect on cyclic plasticity of the coarse-grained specimens is characterized by the increased spacing and the decreased height of slip bands. Crystallographic crack growth was retained in the hydrogen-charged specimen unlike the uncharged specimen. This suggests that dissolved hydrogen restricts the number of the activated slip systems at the crack tip. 相似文献
255.
Quang-Duy Dao Tetsuro Hori Kaoru Fukumura Tetsuya Masuda Toshiya Kamikado Akihiko Fujii Yo Shimizu Masanori Ozaki 《Organic Electronics》2013,14(10):2628-2634
A study on the effects of processing additives on the nanoscale phase separation, crystallization, and photovoltaic performance of bulk heterojunction (BHJ) thin films made of 1,4,8,11,15,18,22,25-octahexylphthalocyanine (C6PcH2) and [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) via spin-casting for photovoltaic applications is reported. By incorporating various solvents as processing additives to a volume of a few percent, the separation of donor and acceptor phases in C6PcH2:PCBM thin films, which discussed by taking the photoluminescence quenching, Davydov splitting at the Q-band of the absorbance spectra and the surface nanomorphology into consideration, is improved, and the crystallinity of the discotic C6PcH2 molecules with hexagonal structures is reinforced. Photovoltaic cells with the optimum phase-separated BHJ materials and high crystallinity of the discotic C6PcH2 molecules are demonstrated to have a power conversion efficiency of 4.2%. 相似文献
256.
Stuart McDonald Kazuhiro Nogita Jonathan Read Tina Ventura Tetsuro Nishimura 《Journal of Electronic Materials》2013,42(2):256-262
Alloys from the composition range Sn-(0.7 wt.% to 7.6 wt.%)Cu consist of primary Cu6Sn5 surrounded by a eutectic Sn-Cu6Sn5 mixture. The primary Cu6Sn5 intermetallics commonly adopt a coarse elongated morphology, which is not optimal for the mechanical properties of the soldered joint. This paper investigates the effect of trace elemental additions on the size and morphology of the primary Cu6Sn5 in Sn-4 wt.%Cu alloy with and without Ni additions. Elements investigated include ppm additions of Al, Ag, Ge, and Pb. It is shown that Al has a marked effect on the solder microstructure and refines the size of the primary Cu6Sn5, even at very low addition levels, in both binary Sn-Cu alloys and those containing additional Ni. The effect of Al is confirmed using real-time x-radiographic synchrotron observations of solidification. 相似文献
257.
258.
Michiko Norizuki Daisuke Takakura Tetsuro Samata 《Frontiers of Materials Science in China》2008,2(2):167-171
We speculated the structure of the N-linked oligosaccharides enzymatically released from the organic matrix (OM) component in the foliated layer of Patinopecten yessoensis. The 80 kDa component of the soluble OM was detected by lectin blotting and was identified as MSP-1 using liquid chromatography/mass
spectrometry (LC/MS/MS). LC/MS/MS analysis of the N-glycan liberated from MSP-1 detected a hybrid-type N-glycan, which contained sulfite and sialic acid at its terminus based on the characteristic Y ions. The data strongly imply
that MSP-1, a sulfated OM glycoprotein, participates in molluscan biomineralization by creating a favorable environment for
calcium ion uptake through sulfite acid and sialic acid. Further analyses of oligosaccharides linked to the OM components
in wide variety of species and shell microstructures may definitely contribute in elucidation of molluscan biomineralization
at the molecular level. 相似文献
259.
Extensive research on human subjects has tried to investigate whether there is a correlation between cognitive performance and the menstrual cycle. Less is known about the relationship between the menstrual cycle and task performance in other cognitive animals. We test whether the secretion of a sex hormone [luteinizing hormone(LH)] influences the performance of cognitive tasks by a female chimpanzee (Pan troglodytes) who is part of a long-term cognition research program. We focus on two cognitive tasks: an “easy task,” which consists of simple numerical ordering, and a “difficult task,” which combines numerical ordering with memorizing the numerals' spatial location. Data on the performance of these cognitive tasks, urine samples, and sexual swelling over six menstrual cycles showed that the chimpanzee's performance accuracy decreased and that the intertrial interval was longer during the LH-surge of the menstrual cycle, but only for the performance of the difficult task. These performance attributes seem to reflect a decrease in attention or motivation during ovulation. In summary, the cognitive performance of a chimpanzee was disturbed by hormonal changes despite her long-term experience in the tasks. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
260.
Transparent ferroelectric PLZT thin films were prepared on fused-quartz substrates by rf sputtering using a powder target
of pulverized ceramic PLZT. The substrate temperature was kept above 550° C to obtain the film. Excess PbO in the target may
act as a sort of flux for crystal growth. The dielectric constant of the film was 500 at room temperature and the film showed
a ferroelectric hysteresis curve. By an appropriate annealing, the transparency of the film became improved. The electrooptic
effects of the film was measured for the first time. The light intensity reflected from the film was changed strongly by application
of the electric field. With light incident at 70° , an intensity change of 33% was obtained at the electric field of 12.5kV/cm. 相似文献