首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   197篇
  免费   1篇
电工技术   7篇
综合类   1篇
化学工业   41篇
金属工艺   6篇
机械仪表   4篇
建筑科学   2篇
能源动力   4篇
轻工业   14篇
无线电   22篇
一般工业技术   28篇
冶金工业   55篇
自动化技术   14篇
  2024年   1篇
  2023年   1篇
  2022年   4篇
  2021年   2篇
  2020年   1篇
  2018年   3篇
  2017年   2篇
  2016年   2篇
  2015年   1篇
  2014年   4篇
  2013年   5篇
  2012年   7篇
  2011年   10篇
  2010年   3篇
  2009年   8篇
  2008年   14篇
  2007年   9篇
  2006年   7篇
  2005年   3篇
  2004年   4篇
  2003年   2篇
  2002年   3篇
  2001年   8篇
  2000年   2篇
  1999年   6篇
  1998年   22篇
  1997年   12篇
  1996年   4篇
  1995年   7篇
  1994年   1篇
  1993年   10篇
  1992年   4篇
  1991年   5篇
  1990年   3篇
  1989年   5篇
  1987年   1篇
  1985年   2篇
  1984年   1篇
  1983年   1篇
  1982年   2篇
  1981年   2篇
  1976年   2篇
  1975年   1篇
  1967年   1篇
排序方式: 共有198条查询结果,搜索用时 0 毫秒
81.
    
Unusual switching of optical-resolution selectivity in chitosan resins is reported. While in hydrophilic chitosan resins, the l -form of amino acids are selectively adsorbed, and in hydrophobic chitosan resins, the d -form was preferred. We found that the adsorption selectivity of the amino acids in the optical-resolution agents is controlled by the hydrophilicity/hydrophobicity or permittivity of the resins, through the Onsager's reaction field. This intriguing selectivity switching is supported by the polarized continuum model calculations. This method provides a promising strategy for switching of optical-resolution preferences by controlling the permittivity of the resins. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48317.  相似文献   
82.
83.
84.
Summary Droplets of water-in-oil-in-water (w/o/w) emulsion were prepared using sodium alginate solution with denitrifying bacteria (Paracoccus denitrificans IFO13301) and dichloromethane (DCM) with polymethylmethacrylate (PMMA). By phase-separation and solvent-evaporation these droplets could be formed into core-shell PMMA microencapsulated denitrifying bacteria (PMMA-MC) possessing a large single core and a highly porous wall. The average thickness of the PMMA shell was 30 μm and the denitrifying bacteria were incorporated in the inner core at a high density. The PMMA-MC completely reduced 20 mg/L nitrate-nitrogen (NO3-N) and the intermediate product, nitrite-nitrogen (NO2-N), to N2 in the presence of H2 using a batchwise method. Thus, incorporated denitrifying bacteria can be used to treat water polluted with NO3-N. The PMMA-MC can be used repeatedly, and the third denitrification experiment directly denitrified (NO3-N → N2) without the intermediate step (NO3-N → NO2-N). In addition, the PMMA-MC with decreased activity could be reactivated by incubating in a culture medium.  相似文献   
85.
Developmental changes in fatty acid hydroperoxide lyase (HPO lyase) and lipoxygenase (LOX) during the maturation of bell pepper fruits (Capsicum annuum L. cv. Kyonami) were examined by means of activity measurements, immunological detection of both the enzymes, and analysis of the volatile compounds formed upon homogenization of the fruits. Both the enzyme activities decreased with maturation, and immunological studies showed that the amounts of the enzymes concomitantly decreased. The amounts of six-carbon aldehydes and alcohols formed from bell pepper fruits upon homogenization also decreased during maturation, and with the fully ripened red fruits, these volatile compounds were hardly detectable. These results suggest that the major factor contributing to the changes in the composition of volatile compounds during the maturation of bell pepper fruits was changes in the amounts of HPO lyase and LOX.  相似文献   
86.
As the upgrade program of the azimuthally varying field (AVF) cyclotron is at the cyclotron facility of the RCNP, Osaka University for the improvement of the quality, stability, and intensity of accelerated beams, an 18 GHz superconducting (SC) ECR ion source has been installed to increase beam currents and to extend the variety of ions, especially for highly charged heavy ions which can be accelerated by RCNP AVF cyclotron. The production development of several ions such as B, O, N, Ne, Ar, Ni, Kr, and Xe has been performed by Yorita et al. [Rev. Sci. Instrum. 79, 02A311(2008); 81, 02A332 (2010)]. Further studies for the beam transport have been done in order to improve the beam current more for injection of cyclotron. The effect of field leakage of AVF main coil is not negligible and additional steering magnet has been installed and then beam transmission has been improved. The emittance monitor has also been developed for the purpose of investigating correlation between emittance of beam from ECR ion sources and injection efficiency. The monitor consists with BPM82 with rotating wire for fast measurement for efficient study.  相似文献   
87.
1. A high oxygen atmosphere induced apoptosis in cultured neuronal cells including PC12 cells and rat embryonic cortical, hippocampal, and basal forebrain neurons associated with DNA fragmentation and nuclear condensation. 2. The sensitivity of CNS neurons to a high-oxygen atmosphere was the following order; cortex > basal forebrain > hippocampus. 3. Cycloheximide and actinomycin-D inhibited the apoptosis, indicating that it depends on new macromolecular synthesis. In contrast, cultured postnatal CNS neurons were resistant to oxidative stress. 4. Neurotrophic factors such as nerve growth factor (NGF), fibroblast growth factor (FGF), and epidermal growth factor (EGF) blocked the apoptosis induced by a high-oxygen atmosphere.  相似文献   
88.
The potential antidepressant properties of indeloxazine hydrochloride were examined in vitro and in vivo. Indeloxazine showed preferential affinity for both [3H] citalopram (Ki: 22.1 nM) and [3H]nisoxetine binding sites (Ki: 18.9 nM) in membranes of the rat cerebral cortex. In microdialysis studies, intraperitoneal injection of indeloxazine (3 and 10 mg/kg) dose-dependently increased the extracellular level of both serotonin and norepinephrine in rat frontal cortex of freely moving rats. Amitriptyline was almost equivalent to indeloxazine in these two assays with the exception of a much weaker effect on extracellular serotonin levels. Spontaneous [3H]serotonin release from rat cortical synaptosomes was significantly enhanced by indeloxazine (10-1000 nM). In behavioral studies, indeloxazine increased the number of wheel rotations in forced swimming tests in both ICR mice (50 mg/kg, p.o.) and SAMP8//YAN, a substrain of senescence-accelerated mouse (20 and 30 mg/kg, p.o.). Indeloxazine (3-10 mg/kg p.o.) also inhibited the incidence of muricide in raphe-lesioned rats. These results suggest that indeloxazine is an inhibitor of serotonin and norepinephrine uptake and has potential antidepressant properties. In addition, the drug-induced enhancement of serotonin release may contribute to its potent effects on the serotonergic system in vivo.  相似文献   
89.
90.
The purpose of the present paper is to examine the hysteretic stress-strain behavior of steel fiber reinforced concrete and steel fiber reinforced mortar under uniaxial compression and to propose mathematical expressions of stress-strain curves based on experimental data. The stress-strain relations are examined in terms of the volume fraction and the aspect ratio of steel fiber. It is indicated in this paper that the normalized stress - strain curves can be described by the proposed simple numerical model with a fairly good accuracy.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号