全文获取类型
收费全文 | 752篇 |
免费 | 17篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 37篇 |
综合类 | 2篇 |
化学工业 | 268篇 |
金属工艺 | 32篇 |
机械仪表 | 22篇 |
建筑科学 | 9篇 |
能源动力 | 38篇 |
轻工业 | 40篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 42篇 |
一般工业技术 | 149篇 |
冶金工业 | 10篇 |
原子能技术 | 56篇 |
自动化技术 | 64篇 |
出版年
2023年 | 4篇 |
2022年 | 6篇 |
2021年 | 13篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 11篇 |
2017年 | 5篇 |
2016年 | 16篇 |
2015年 | 15篇 |
2014年 | 21篇 |
2013年 | 50篇 |
2012年 | 40篇 |
2011年 | 56篇 |
2010年 | 34篇 |
2009年 | 28篇 |
2008年 | 53篇 |
2007年 | 37篇 |
2006年 | 35篇 |
2005年 | 28篇 |
2004年 | 27篇 |
2003年 | 25篇 |
2002年 | 30篇 |
2001年 | 20篇 |
2000年 | 22篇 |
1999年 | 19篇 |
1998年 | 11篇 |
1997年 | 13篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 11篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 11篇 |
1989年 | 4篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 13篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有772条查询结果,搜索用时 0 毫秒
41.
Adaptive interpolation scheme for NURBS curves with the integration of machining dynamics 总被引:13,自引:4,他引:13
Xianbing Liu Fahad Ahmad Kazuo Yamazaki Masahiko Mori 《International Journal of Machine Tools and Manufacture》2005,45(4-5):433-444
This paper develops a comprehensive interpolation scheme for non-uniform rational B-spline (NURBS) curves, which does not only simultaneously meet the requirements of both constant feedrate and chord accuracy, but also real-time integrates machining dynamics in the interpolation stage. Although the existing work in this regard has realized the importance to simultaneously consider chord error and machining dynamics, none has really incorporated these in one complete interpolation scheme. In this paper, machining dynamics is considered for three aspects: sharp corners or feedrate sensitive corners on the curves, components with high frequencies or frequencies matching machine natural ones and high jerks. A look-ahead module was developed for detecting and adaptively adjusting the feedrate at the sharp corners. By Fast Fourier Transform (FFT) analysis with a moving window in the interpolation stage identified were some special frequency components such as those containing high frequencies or with frequencies matching machine natural ones. Then, the notch filtering or time spacing method was used to eliminate these components. To more completely reduce feedrate and acceleration fluctuations, the jerk-limited algorithm was also developed. Finally, the interpolated feedrate was further smoothened with B-spline fitting method and the NURBS curves were re-interpolated with the smoothened feedrate. During the interpolation, the chord error was repeatedly checked and confined in the prescribed tolerance. Two NURBS curves were used as examples to test the feasibility of the developed interpolation scheme. 相似文献
42.
Xiangchun Meng Haiyang Cheng Shin-ichiro Fujita Yufen Hao Yanjiao Shang Yancun Yu Shuxia Cai Fengyu Zhao Masahiko Arai 《Journal of Catalysis》2010,269(1):131-139
The hydrogenation of chloronitrobenzene to chloroaniline was investigated over Ni/TiO2 at 35 °C in supercritical CO2 (scCO2), ethanol, and n-hexane. The reaction rate followed the order of scCO2 > n-hexane > ethanol. In scCO2, the selectivity to chloroaniline and to aniline over Ni/TiO2 were 97–99.5% and <1%, respectively, in the conversion range of 9–100%. The high chemoselectivity to chloroaniline cannot be achieved over Ni/TiO2 in ethanol and n-hexane. In situ high-pressure Fourier transform infrared measurements were made to study the molecular interactions of CO2 with the following reactant and reaction intermediates: chloronitrobenzene, chloronitrosobenzene, and N-chlorophenylhydroxylamine. The molecular interaction modifies the reactivity of each species and accordingly the reaction rate and the selectivity. The influence of Cl substituent on the interaction modes of CO2 with these reacting species is discussed. Possible reaction pathways for the hydrogenation of chloronitrobenzene in scCO2 over Ni/TiO2 are also proposed. 相似文献
43.
Eisuke Watanabe Junko Fujii Kaori Kojima Satoshi Iwatsuki Masahiko Inamo Hideo D. Takagi Koji Ishihara 《Inorganic chemistry communications》2010,13(12):1406-1409
Kinetic studies were performed on the reactions of phenylboronic acid with L-lactic acid and mandelic acid in acidic aqueous and alkaline solutions in order to specify reactive species in these reactions. It was confirmed that the diprotonated ligand (H2L: L-lactic acid or mandelic acid) is less reactive than the monoprotonated ligand (HL?: L-lactate ion or mandelate ion), which made possible direct determination of the rate constants of phenylboronic acid (PhB(OH)2) and its conjugate base, phenylboronate ion (PhB(OH)3?). It was found that PhB(OH)2 is more reactive than PhB(OH)3?. On the basis of kinetic results, it was concluded that the most reactive species are PhB(OH)2 and HL? at physiological pH 7.4, so the reaction in the boronic acid-based sensor for L-lactate mainly would occur between these species. 相似文献
44.
Ryoka Uchiyama Eriko Toyoda Miki Maehara Shiho Wasai Haruka Omura Masahiko Watanabe Masato Sato 《International journal of molecular sciences》2021,22(5)
Osteoarthritis of the knee (OAK) is a chronic degenerative disease and progresses with an imbalance of cytokines and macrophages in the joint. Studies regarding the use of platelet-rich plasma (PRP) as a point-of-care treatment for OAK have reported on its effect on tissue repair and suppression of inflammation but few have reported on its effect on macrophages and macrophage polarization. Based on our clinical experience with two types of PRP kits Cellaid Serum Collection Set P type kit (leukocyte-poor-PRP) and an Autologous Protein Solution kit (APS leukocyte-rich-PRP), we investigated the concentrations of humoral factors in PRPs prepared from the two kits and the effect of humoral factors on macrophage phenotypes. We found that the concentrations of cell components and humoral factors differed between PRPs purified using the two kits; APS had a higher concentration of M1 and M2 macrophage related factors. The addition of PRP supernatants to the culture media of monocyte-derived macrophages and M1 polarized macrophages revealed that PRPs suppressed M1 macrophage polarization and promoted M2 macrophage polarization. This research is the first to report the effect of PRPs purified using commercial kits on macrophage polarization. 相似文献
45.
Takashi Ohnishi Yuki Ogawa Kota Suda Miki Komatsu Satoko Matsumoto Harmon Mitsuru Asukai Masahiko Takahata Norimasa Iwasaki Akio Minami 《International journal of molecular sciences》2021,22(9)
Pyogenic spondylodiscitis can cause severe osteolytic and destructive lesions in the spine. Elderly or immunocompromised individuals are particularly susceptible to infectious diseases; specifically, infections in the spine can impair the ability of the spine to support the trunk, causing patients to be bedridden, which can also severely affect the physical condition of patients. Although treatments for osteoporosis have been well studied, treatments for bone loss secondary to infection remain to be elucidated because they have pathological manifestations that are similar to but distinct from those of osteoporosis. Recently, we encountered a patient with severely osteolytic pyogenic spondylodiscitis who was treated with romosozumab and exhibited enhanced bone formation. Romosozumab stimulated canonical Wnt/β-catenin signaling, causing robust bone formation and the inhibition of bone resorption, which exceeded the bone loss secondary to infection. Bone loss due to infections involves the suppression of osteoblastogenesis by osteoblast apoptosis, which is induced by the nuclear factor-κB and mitogen-activated protein kinase pathways, and osteoclastogenesis with the receptor activator of the nuclear factor-κB ligand-receptor combination and subsequent activation of the nuclear factor of activated T cells cytoplasmic 1 and c-Fos. In this study, we review and discuss the molecular mechanisms of bone loss secondary to infection and analyze the efficacy of the medications for osteoporosis, focusing on romosozumab, teriparatide, denosumab, and bisphosphonates, in treating this pathological condition. 相似文献
46.
47.
Kotaka A Bando H Kaya M Kato-Murai M Kuroda K Sahara H Hata Y Kondo A Ueda M 《Journal of Bioscience and Bioengineering》2008,105(6):622-627
Three beta-glucosidase- and two endoglucanase-encoding genes were cloned from Aspergillus oryzae, and their gene products were displayed on the cell surface of the sake yeast, Saccharomyces cerevisiae GRI-117-UK. GRI-117-UK/pUDB7 displaying beta-glucosidase AO090009000356 showed the highest activity against various substrates and efficiently produced ethanol from cellobiose. On the other hand, GRI-117-UK/pUDCB displaying endoglucanase AO090010000314 efficiently degraded barley beta-glucan to glucose and smaller cellooligosaccharides. GRI-117-UK/pUDB7CB codisplaying both beta-glucosidase AO090009000356 and endoglucanase AO090010000314 was constructed. When direct ethanol fermentation from 20 g/l barley beta-glucan as a model substrate was performed with the codisplaying strain, the ethanol concentration reached 7.94 g/l after 24 h of fermentation. The conversion ratio of ethanol from beta-glucan was 69.6% of the theoretical ethanol concentration produced from 20 g/l barley beta-glucan. These results showed that sake yeast displaying A. oryzae cellulolytic enzymes can be used to produce ethanol from cellulosic materials. Our constructs have higher ethanol production potential than the laboratory constructs previously reported. 相似文献
48.
Elly Setiawati Masahiko HayashiMasaya Takahashi Takahisa ShodaiKeiichi Saito 《Journal of power sources》2011,196(23):10133-10140
Lithium titanium oxide (LTO) with a ramsdellite structure is an advantageous anode for lithium ion secondary batteries, because of its positive potential, which is beneficial for safety reasons. In addition, compared with other titanate anodes, it has a superior theoretical capacity of 321 mA h g−1, which is close to the capacity of a practical carbonaceous anode. Our study showed that this ramsdellite-type LTO had a high discharge capacity that is stable at 250 mA h g−1 at a current density of 1 mA cm−2. However, this high capacity is only achieved by employing as-synthesized ramsdellite LTO powder. When the same powder was stored and the same evaluation was carried out, the resulting capacity was 200 mA h g−1, which is lower than the capacity of as-synthesized powder. An annealing applied to the ramsdellite LTO powder appeared to restore the capacity loss after storage. Annealing at 250 °C for 5 h produced the best performance, which was even better than that obtained using the as-synthesized ramsdellite LTO powder. Moreover, we investigated the surface property of ramsdellite LTO and found that the presence of a carbon derivative is apparently responsible for blocking the Li ions insertion/extraction, and thus reducing the capacity. 相似文献
49.
Yasushi Sekine Haruka Takamatsu Sho Aramaki Kazuki Ichishima Mitsuko Takada Masahiko Matsukata Eiichi Kikuchi 《Applied Catalysis A: General》2009,352(1-2):214-222
The water gas shift (WGS) reaction over Pt and Pd catalysts supported on various perovskite oxides has been investigated at 573 K without catalyst pretreatment. The Pt and Pd catalysts on LaCoO3 support showed high catalytic activity. Interaction between Pt or Pd and the support is considered to promote the WGS reaction: Pt/LaCoO3 had high initial activity but deactivated immediately; Pd/LaCoO3 was less active than Pt/LaCoO3, but had superior stability. Catalysts were characterized using XRD, STEM, XPS, and H2-temperature programmed reduction (TPR). Results of this study showed that reduction of the support decreased the CO conversion on Pt/LaCoO3. On the other hand, Pd/LaCoO3 showed stable activity for the WGS reaction. Therefore, Pd was added to Pt/LaCoO3 for stabilizing the catalyst activity, and 0.5 wt.% Pd/1 wt.% Pt/LaCoO3 catalyst showed higher activity and stability. 相似文献
50.