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21.
Maurice I. Osotsi Daniel K. Machari Bo Zhu Zhaojie Wang Xiaofeng Shen Zixiao Liu Lisha Zhang Zhigang Chen 《自然科学进展(英文版)》2018,28(4):408-415
Persistent organic pollutants (POPs) especially tetracycline pose a great threat to human health, and the photocatalytic
degradation of tetracycline by ZnWO4 nanomaterials has drawn much attention. To improve the
photo-response range and photoactivity, we prepared ZnWO4?x sample with oxygen vacancies by solvothermally
treating Zn(NO3)3 and Na2WO4 in water/ethanol/PEG-400 mixture where ethanol could act as a reducing
agent to selectively remove some oxygen atoms from ZnWO4. ZnWO4?x sample is composed of nanorods with
length of ~50 nm and diameter of ~20 nm. Furthermore, ZnWO4?x nanorods are brown and exhibit the obviously
broadened photoabsorption from ultraviolet (UV) to near infrared (NIR) region, compared with the
tradition white ZnWO4 nanorod without oxygen vacancies and with UV absorption edge of 365 nm. Under the
irradiation of UV or ultraviolet-visible-near infrared (UV–Vis–NIR) light, ZnWO4?x nanorods can photocatalytically
degrade 91% or 78% tetracycline, higher than those (67% or 71%) by ZnWO4 nanorods. The enhanced
photocatalytic efficiency can be attributed to the introduction of oxygen vacancies which have been
found to reduce photogenerated electron-hole pair recombination and narrow band gap. 相似文献
22.
Jiao Demao Li Xia Huang Xueqing Chi Wei Kuang Tingyun Ku S. B. Maurice 《科学通报(英文版)》2001,46(13):1080-1084
With PEPC, PPDK, NADP-ME and PEPC+ PPDK transgenic and untransformed rice (Orysa sativa L.), the activities of related C4 photosynthesis enzymes, the chlorophyll fluorescence parameters, CO2 exchange and other physiological indexes were compared, in which the physiological characteristics of PEPC transgenic rice were mainly studied. The results were as follows: (ⅰ) The activities of PEPC in PEPC transgenic rice were 20-fold higher than those in untransformed rice; the light-saturation photosynthetic rates and the carboxylation efficiency of PEPC transgenic rice were increased by 55% and 50% more than those of untransformed rice, respectively, while the CO2 compensation point decreased by 27%. (ⅱ) The PSⅡ photochemical efficiency (Fv/Fm) and photochemical quenching (qP) of transgenic PEPC rice decreased less in comparison with those of untransformed rice after the treatment with high light intensity (3 h) or methyl viologen (MV), a photooxidative reagent, which demonstrated that the tolerance of PEPC transgenic rice to photoinhibition and photooxidation was enhanced. (ⅲ) Under the condition of high light intensity, the activity of RuBPCase in PEPC transgenic rice did not obviously vary while the activity induced of carbonic anhydrase (CA) in PEPC transgenic rice increased by 1.8 fold. These results would provide some beneficial enlightment for revealing the mechanism of high photosynthetic efficiency and breeding with high photosynthetic efficiency in rice. 相似文献
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McKern NM Lawrence MC Streltsov VA Lou MZ Adams TE Lovrecz GO Elleman TC Richards KM Bentley JD Pilling PA Hoyne PA Cartledge KA Pham TM Lewis JL Sankovich SE Stoichevska V Da Silva E Robinson CP Frenkel MJ Sparrow LG Fernley RT Epa VC Ward CW 《Nature》2006,443(7108):218-221
The insulin receptor is a phylogenetically ancient tyrosine kinase receptor found in organisms as primitive as cnidarians and insects. In higher organisms it is essential for glucose homeostasis, whereas the closely related insulin-like growth factor receptor (IGF-1R) is involved in normal growth and development. The insulin receptor is expressed in two isoforms, IR-A and IR-B; the former also functions as a high-affinity receptor for IGF-II and is implicated, along with IGF-1R, in malignant transformation. Here we present the crystal structure at 3.8 A resolution of the IR-A ectodomain dimer, complexed with four Fabs from the monoclonal antibodies 83-7 and 83-14 (ref. 4), grown in the presence of a fragment of an insulin mimetic peptide. The structure reveals the domain arrangement in the disulphide-linked ectodomain dimer, showing that the insulin receptor adopts a folded-over conformation that places the ligand-binding regions in juxtaposition. This arrangement is very different from previous models. It shows that the two L1 domains are on opposite sides of the dimer, too far apart to allow insulin to bind both L1 domains simultaneously as previously proposed. Instead, the structure implicates the carboxy-terminal surface of the first fibronectin type III domain as the second binding site involved in high-affinity binding. 相似文献
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基于EKF的PMSM无机械传感器矢量控制 总被引:2,自引:0,他引:2
为了准确估计永磁同步电机(PMSM)的转子位置和转速,并实现无机械传感器矢量控制,提出了一种基于扩展Kalman滤波器(EKF)的转子位置和转速观测器,适合于求解永磁同步电机的非线性方程。观测器状态方程采用转子磁链定向的同步旋转坐标系下的电压方程,电感等参数为常数,可以应用于凸极机和隐极机。对扩展Kalman滤波器进行了算法简化,使它可以实用化。把负载转矩作为状态变量,观测器可以同时观测负载转矩,并把观测转矩用作前馈补偿,提高了系统的动态性能。通过实验验证了系统的性能。 相似文献
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Bencze Larry Di Giuseppe Maurice Hodson Derek Pedretti Erminia Serebrin Lisa Decoito Isha 《Systemic Practice and Action Research》2003,16(5):285-308
Although governments espouse development in students of comprehensive science literacy, excessive teaching of achievements of science tends to compromise students' development of realistic conceptions about science and expertise for doing science. For most students, school science is like being chained inside Plato's cave, only able to experience and interpret the world of science from flickering, shadowy images. This can be particularly problematic for students in elementary schools, who may not be developmentally ready for abstract topics inherent to nature of science discussions and whose teachers tend to have low science self-efficacy beliefs. In the mainly qualitative ethnographic study of a 3-year, large-scale collaborative action research project reported here, a significant additional factor limiting students' access to more contemporary views about and realistic experiences with science, however, was government curriculum policy—which promotes highly idealized portrayals of and regulated experiences with science. Data and arguments for these claims are provided. 相似文献
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