全文获取类型
收费全文 | 674篇 |
免费 | 28篇 |
国内免费 | 7篇 |
学科分类
工业技术 | 709篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 24篇 |
2020年 | 8篇 |
2019年 | 9篇 |
2018年 | 10篇 |
2017年 | 13篇 |
2016年 | 13篇 |
2015年 | 10篇 |
2014年 | 18篇 |
2013年 | 36篇 |
2012年 | 35篇 |
2011年 | 53篇 |
2010年 | 36篇 |
2009年 | 31篇 |
2008年 | 40篇 |
2007年 | 34篇 |
2006年 | 47篇 |
2005年 | 37篇 |
2004年 | 19篇 |
2003年 | 21篇 |
2002年 | 24篇 |
2001年 | 11篇 |
2000年 | 14篇 |
1999年 | 16篇 |
1998年 | 9篇 |
1997年 | 9篇 |
1996年 | 9篇 |
1995年 | 8篇 |
1994年 | 8篇 |
1993年 | 4篇 |
1992年 | 8篇 |
1991年 | 9篇 |
1990年 | 9篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1980年 | 8篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1966年 | 1篇 |
排序方式: 共有709条查询结果,搜索用时 796 毫秒
91.
Acremonium cellulolyticus is a fungus that produces cellulase and has been exploited by enzyme industry. To promote cellulase production by A. cellulolyticus strain C-1, we evaluated the effects of the saccharides: Solka Floc (cellulose), soluble soybean polysaccharide (SSPS), pullulan, lactose, trehalose, sophorose, cellobiose, galactose, sorbose, lactobionic acid, and mixtures as carbon sources for cellulase production. Solka Floc with SSPS enhanced cellulase production. Lactose as the sole carbon source induced cellulase synthesis in this fungus, and the synergistic effects between lactose and Solka Floc was observed. Various enzyme activities and the protein composition of crude enzyme produced by cultures with or without addition of lactose were analyzed. The results showed that lactose addition greatly improves the production of various proteins with cellulase activity by A. cellulolyticus. To our knowledge, this is the first report on production of cellulases by lactose in the A. cellulolyticus. 相似文献
92.
Kazuko Iwamoto Shinichi Matsumura Yuri Yoshioka Ayami Yamamoto Shohei Makino Tatsuya Moriyama Nobuhiro Zaima 《Lipids》2019,54(5):311-320
Accumulation of amyloid-β peptide is associated with Alzheimer's dementia. Previously, we reported that sesamin and sesamolin inhibited β-secretase activity in vitro, and each was transported to the serum and brain in mice after oral administration. However, the bioavailability of sesamin and sesamolin was poor in mice. In this study, we aimed to improve the bioavailability of sesamin and sesamolin. We found that the levels of sesamin and sesamolin in mouse serum and brain were higher after the administration of a mixture of sesame extract and turmeric oil (MST) than those after administering sesame extract alone. Serum sesamin and sesamolin contents in the MST-treated group were 23-fold and 15-fold higher, respectively, than those in the sesame extract-treated group. Brain sesamin and sesamolin contents in the MST-treated group were 14-fold and 11-fold higher, respectively, than those in the sesame extract-treated group. These results suggest that turmeric oil is an effective solvent to enhance the bioavailability of sesamin and sesamolin. 相似文献
93.
Minami Sakamoto Tomomitsu Miyagaki Hiroaki Kamijo Tomonori Oka Hikari Boki Naomi Takahashi-Shishido Hiraku Suga Makoto Sugaya Shinichi Sato 《International journal of molecular sciences》2021,22(15)
CD147, a transmembrane glycoprotein that belongs to the immunoglobulin superfamily, and cyclophilin A (CypA), one of the binding partners of CD147, are overexpressed in tumor cells and associated with the progression of several malignancies, including both solid and hematological malignancies. However, CD147 and CypA involvement in cutaneous T-cell lymphoma (CTCL) has not been reported. In this study, we examined CD147 and CypA expression and function using clinical samples of mycosis fungoides (MF) and Sézary syndrome (SS) and CTCL cell lines. CD147 and CypA were overexpressed by tumor cells of MF/SS, and CypA was also expressed by epidermal keratinocytes in MF/SS lesional skin. Serum CypA levels were increased and correlated with disease severity markers in MF/SS patients. Anti-CD147 antibody and/or anti-CypA antibody suppressed the proliferation of CTCL cell lines, both in vitro and in vivo, via downregulation of phosphorylated extracellular-regulated kinase 1/2 and Akt. These results suggest that CD147-CypA interactions can contribute to the proliferation of MF/SS tumor cells in both a autocrine and paracrine manner, and that the disruption of CD147-CypA interactions could be a new therapeutic strategy for the treatment of MF/SS. 相似文献
94.
Dalia Heggo Shinichi Ookawara Teruhisa Ohno Toru Nakai Yoshihisa Matsushita Mona Gamal Eldin Masahiro Ohshima 《加拿大化工杂志》2020,98(1):119-126
Dense photocatalyst slurry was employed for the synthesis of p-anisaldehyde under solar light irradiation. An Fe-modified rutile TiO 2 (Fe-TiO 2, 34.5 m 2/g) photocatalyst was used as a visible-light-responsive photocatalyst. A conventional TiO 2 (P25, 35 m 2/g) photocatalyst was also examined as a reference catalyst. XRD patterns and diffuse reflectance spectra showed that Fe-TiO 2 consists of 100 % rutile phase and absorbs more visible light compared to P25, respectively. The catalyst powder was suspended in an ethyl acetate solution of p-methoxytoluene in the mini-reactor, with oxygen bubbling, under a solar simulator, visible light, and UV LEDs. p-anisaldehyde, as a reaction product, was analyzed by sampling using gas-chromatograph. Regardless of the light source, Fe-TiO 2 always outperformed P25 in terms of both generation rates (GR) of p-anisaldehyde and energy requirements (ER). It was demonstrated that the highly dense Fe-TiO 2 slurry was efficient for the synthesis under solar light owing to the small size of the reactor. The small amount of Pt and ZrO 2 cocatalysts significantly enhanced the GR under solar light. By adopting a visible light responsive Fe-TiO 2 photocatalyst, the mini slurry-bubble reactor under solar light achieved a high GR per catalyst mass (CM), which is one to two orders higher than that reported by most previous studies with high-power lamps. 相似文献
95.
John McGrady Shinichi Yamashita Atsushi Kimura Sho Kano Huilong Yang Zhengang Duan 《Journal of Nuclear Science and Technology》2020,57(4):463-471
ABSTRACTTypical metal oxide corrosion products of structural materials have been irradiated with γ-rays in ultra-pure water to investigate the effect of radiation on the surface oxide and the nature of adsorbed water. Analysis techniques including thermal gravimetric analysis, differential thermal analysis, diffuse reflectance infrared Fourier transform spectroscopy, and X-ray photoelectron spectroscopy before and after γ-irradiation were employed to investigate surface structural effects and adsorbed water behaviour. The production of H2 in the oxide nanoparticle mixtures was investigated by gas chromatography to probe the mechanism of radiolysis in the water/oxide mixtures and the relationship with surface water. The nature of water at the surface of the oxides was affected by γ-radiation and the relationship was dependent on the particle composition. The rate of H2 production was shown to be oxide dependent, and higher rates of H2 formation were attributed to the decomposition of surface adsorbed water. Changes to the surface chemistry and H2 production rates were found to be highly dependent on the surface chemistry of the metal oxide nanoparticle and no bulk structural changes were observed. 相似文献
96.
New serpentine and spiral flow field configurations were developed to enhance the performance of direct methanol fuel cells (DMFCs). The new configurations are based on two primary concepts, namely, narrowing the flow field and partitioning the total active area of the fuel cell. Three flow channel heights of 0.8, 0.4, and 0.2 mm were investigated in serpentine and spiral flow fields. The main active area is considered a single zone and is partitioned into two‐ and four‐zone designs while maintaining the total inlet mass flow rate of the reactant and oxidant. To determine the performance parameters of the newly proposed designs, a three‐dimensional single‐phase isothermal model was developed, numerically simulated, and validated through experimental measurements. The findings of the current study indicate that a serpentine flow field configuration with a channel height of 0.2 mm and two zones attains an enhancement of the net power density of 37% compared to a conventional single‐zone design with a flow channel height of 0.8 mm. Similarly, for a spiral flow field design, the maximum net power density increased by 26% using a two‐zone configuration with a channel height of 0.2 mm, in comparison to the conventional design of a single‐zone and a flow channel height of 0.8 mm. The newly developed designs utilize the lower height of the flow fields to decrease the dimensions of the fuel cell stacks and reduce the material costs required. 相似文献
97.
Tetsuji Kaneko Norihiko Tanaka Shinichi Ishioka Fujii Kazumi Yuichi Fukaya Katsuhiko Kumagai 《Journal of Nuclear Science and Technology》2019,56(9-10):873-880
ABSTRACTFukushima Daiichi nuclear power plants (1F) were damaged by unprecedented severe accident in the great east Japan earthquake, and seawater and freshwater had been injected as an emergency countermeasure for the core cooling. Although, the primary containment vessel (PCV) was not supposed to be exposed to diluted seawater, the PCV will be exposed to diluted seawater environment until fuel debris removal is completed. Therefore, it is necessary to establish a countermeasure of corrosion for the PCVs made of carbon steel. In this study, the effect of the addition of corrosion inhibitor, which is one of the corrosion countermeasures, was investigated by two types of corrosion tests. As a result of the immersion corrosion test, it was found that any of the three kinds of corrosion inhibitor could suppress corrosion of carbon steel. In addition, as a result of the inhibitor interim addition test, it was found that corrosion of carbon steel covered with corrosion products could be suppressed by optimizing the additive amount of corrosion inhibitor in the cooling water. 相似文献
98.
The impact-echo method has been extensively applied to nondestructive evaluation of defects in concrete structures. The presence and the location of defects in concrete are estimated by identifying peak frequencies in the frequency spectra. To detect ungrouted tendon ducts, the method is known to be available. However, because post-tensioning prestressed concrete members usually have thin web portions, spectra obtained could include many peak frequencies. As a result, it is often problematic to select appropriate peak frequencies associated with the presence of ungrouted ducts. Stack imaging of spectral amplitudes based on impact-echo (SIBIE) is developed, in order to improve the impact-echo and to visually identify the locations of such reflectors as voids and defects. In the present paper, SIBIE is successfully applied to identify ungrouted metal and plastic sheaths at the hunch portion of a prestressed concrete beam. Two-dimensional dynamic BEM analysis is performed to investigate the relations between peak frequencies and locations of reflectors. At the peak frequencies in the spectra, locations of stress concentration are correlated with the response modes. 相似文献
99.
Marek E. Schmidt Manoharan Muruganathan Teruhisa Kanzaki Takuya Iwasaki Ahmed M. M. Hammam Shunei Suzuki Shinichi Ogawa Hiroshi Mizuta 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(46)
The predicted quasiparticle energy gap of more than 1 eV in sub‐6 nm graphene nanoribbons (GNRs) is elusive, as it is strongly suppressed by the substrate dielectric screening. The number of techniques that can produce suspended high‐quality and electrically contacted GNRs is small. The helium ion beam milling technique is capable of achieving sub‐5 nm patterning; however, the functional device fabrication and the electrical characteristics are not yet reported. Here, the electrical transport measurement of suspended ≈6 nm wide mono‐ and bilayer GNR functional devices is reported, which are obtained through sub‐nanometer resolution helium ion beam milling with controlled total helium ion budget. The transport gap opening of 0.16–0.8 eV is observed at room temperature. The measured transport gap of the different edge orientated GNRs is in good agreement with first‐principles simulation results. The enhanced electron–electron interaction and reduced dielectric screening in the suspended quasi‐1D GNRs and anti‐ferromagnetic coupling between opposite edges in the zigzag GNRs substantiate the observed large transport gap. 相似文献
100.
Large Magnetovolume Effect Induced by Embedding Ferromagnetic Clusters into Antiferromagnetic Matrix of Cobaltite Perovskite 下载免费PDF全文
Ping Miao Xiaohuan Lin Akihiro Koda Sanghyun Lee Yoshihisa Ishikawa Shuki Torii Masao Yonemura Takashi Mochiku Hajime Sagayama Shinichi Itoh Kazutaka Ikeda Toshiya Otomo Yinxia Wang Ryosuke Kadono Takashi Kamiyama 《Advanced materials (Deerfield Beach, Fla.)》2017,29(27)
Materials that show negative thermal expansion (NTE) have significant industrial merit because they can be used to fabricate composites whose dimensions remain invariant upon heating. In some materials, NTE is concomitant with the spontaneous magnetization due to the magnetovolume effect (MVE). Here the authors report a new class of MVE material; namely, a layered perovskite PrBaCo2O5.5+x (0 ≤ x ≤ 0.41), in which strong NTE [β ≈ ?3.6 × 10?5 K?1 (90–110 K) at x = 0.24] is triggered by embedding ferromagnetic (F) clusters into the antiferromagnetic (AF) matrix. The strongest MVE is found near the boundary between F and AF phases in the phase diagram, indicating the essential role of competition between the F‐clusters and the AF‐matrix. Furthermore, the MVE is not limited to the PrBaCo2O5.5+x but is also observed in the NdBaCo2O5.5+x . The present study provides a new approach to obtaining MVE and offers a path to the design of NTE materials. 相似文献