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251.
该文研究了在超高性能声表面波(I.H.P. SAW)衬底上,孔径总长对叉指末端具有能够抑制横向模态的小锤结构的谐振器性能。在衬底结构为Y 42°-钽酸锂(Y42°-LT)/SiO2/多晶硅(Poly-Si)/Si上,通过建立对应的有限元三维仿真模型,初步得出在小锤结构下孔径总长的增大能够抑制横向模态杂散的结论。绘制了周期T为1.44μm、2μm、2.56μm下,孔径总长为7.5T、10T、15T、20T、25T、32.5T、40T的单端口谐振器版图并进行流片。通过实测结果表明,在不同周期下,随着孔径总长的不断增加,对谐振器横向模态的抑制会不断增强,机电耦合系数也不断增加,在孔径总长约为20T时阻抗比最高。仿真和实测结果体现了孔径总长对I.H.P. SAW谐振器的性能影响较大,为应用于I.H.P. SAW滤波器中的高性能谐振器提供了设计指导。 相似文献
252.
建设有深度、有难度、有挑战度的"金课",是每个教师都面临的挑战.本文以"电磁场工程应用"课程的"电导和接地电阻"为例,介绍其高阶课堂的构建过程.在课程教学中,采取线上线下混合式教学模式.在线下课程中,采取"思考"+"讨论"的"问号课堂",激发学生思考和讨论.采取适当"吊胃口"的方式,达到让学生"既疑又懂"的效果,尽量做到"思中学"、"做中学",培养学生主动学习和主动实践能力. 相似文献
253.
通过高能离子注入剥离制备的铌酸锂(LNO)单晶薄膜具备优良的电光、声光等性能,在射频器件、光波导等领域需求迫切。高能离子注入使LNO单晶薄膜表面存在损伤层,导致薄膜质量和器件性能的衰减。该文提出了Ar+刻蚀去除LNO单晶薄膜损伤层的方法,基于高能离子注入仿真,采用扫描电子显微镜、原子力显微镜分析了刻蚀参数对刻蚀速率、表面形貌的影响,并确定了LNO薄膜损伤层的刻蚀工艺参数。X线衍射分析表明,通过Ar+刻蚀将LNO薄膜摇摆曲线半高宽减至接近注入前LNO单晶材料,压电力显微镜测试表明去除损伤层后的LNO单晶薄膜具备更一致的压电响应。 相似文献
254.
255.
GAO Shengli CHEN Sanping JIAO Baojuan SHUAI Qi & SHI Qizhen Department of Chemistry Shaanxi Key Laboratory of Physico-lnorganic Chemistry Northwest University Xi''''an China 《中国科学B辑(英文版)》2005,48(Z1)
The enthalpy change of formation of the reaction of hydrous dysprosium chloride with ammonium pyrrolidinedithiocarbamate (APDC) and 1,10-phenanthroline (o-phen·H2O) in absolute ethanol at 298.15 K has been determined as (-16.12±0.05) kJ·mol-1 by a microcalor-meter. Thermodynamic parameters (the activation enthalpy, the activation entropy and the activation free energy), rate constant and kinetics parameters (the apparent activation energy, the pre-exponential constant and the reaction order) of the reaction have also been calculated. The enthalpy change of the solid-phase reaction at 298.15 K has been obtained as (53.59±0.29) kJ·mol-1 by a thermochemistry cycle. The values of the enthalpy change of formation both in liquid-phase and solid-phase reaction indicated that the complex could only be synthesized in liquid-phase reaction. 相似文献
256.
257.
Peng Zhang Jiquan Wang Yuan Li Lisha Jiang Zhuangzhuang Wang Gaoke Zhang 《物理化学学报》1985,37(8):2009102-0
Energy crisis has become a serious global issue due to the increasing depletion of fossil fuels; therefore, it is crucial to develop environmentally friendly and renewable energy resources, such as hydrogen (H2), to replace fossil fuels. From this viewpoint, photocatalytic H2 production is considered as one of the most promising technologies. Noble metal platinum (Pt) can be applied as an efficient cocatalyst for improving the H2 production performance of photocatalytic systems; however, its high cost limits its further application. Thus, the development of novel, high-activity, and low-cost cocatalysts for replacing noble metal cocatalysts is of great significance for use in photocatalytic H2 evolution techniques. Herein, we successfully synthesized a Ni2P/graphite-like carbonitride photocatalyst (Ni2P/CN) using a conjugated polymer (SCN)n as precursor for enhanced photocatalytic H2 production under visible light illumination. Various characterization techniques, including optical and photoelectronic chemical tests, were used to investigate the structural composition, morphology, and light adsorption ability of these materials. X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy results showed that Ni2P/CN nanocomposites with good crystal structure were obtained. Scanning electron microscopy and transmission electron microscopy results revealed that the Ni2P/CN samples had a typical two-dimensional layered structure, and the Ni2P nanoparticles were uniformly loaded on the surface of the CN to form a non-noble metal promoter. UV-Vis diffuse reflectance spectra results demonstrated that the loading of Ni2P nanoparticles effectively enhances the adsorption capacity of CN to visible light. Photoluminescence spectroscopy and photocurrent (PL) results suggested that Ni2P loading to CN is beneficial for promoting the migration and separation efficiency of photogenerated carriers. Photocatalytic H2 production was conducted under visible light irradiation with triethanolamine as a sacrificial agent. The results suggest that the Ni2P/CN composite photocatalysts exhibit excellent photocatalytic reduction performance. In particular, the H2 evolution rate of the optimal Ni2P/CN nanocomposite is 623.77 μmol·h-1·g-1, which is higher than that of CN modified by noble metal Pt, i.e., 524.63 μmol·h-1·g-1. In conclusion, Ni2P nanoparticles are homogeneously attached to the surface of CN, and a strong interfacial effect exists between them, thereby forming an electron transfer tunnel that greatly inhibits the recombination of photoinduced carriers and promotes the migration of electrons from CN to Ni2P. In addition, a possible photocatalytic mechanism is proposed based on the experiments and characterizations. This work has profound significance for developing non-noble metal cocatalysts for the substitution of noble metal cocatalysts for high-efficiency photocatalytic H2 evolution.
相似文献
258.
Yue Sun Zeshuai Yao Guangyu Wang Lisha Wang Prof. Min Bai Prof. Dr. Hu Shi 《Chemphyschem》2023,24(6):e202200710
Zn2+ is a very important factor in promoting the formation of amyloid beta (Aβ) aggregates and amyloid plaques. The Zn2+-bound Aβ species generate amorphous or low molecular-weight oligomers. However, it is a lack of studies to approach the starting structural features (dimerization) in Aβ nucleation processes with and without Zn2+, which is the key point in understanding Zn2+-induced nucleation mechanisms. To better understand the effect of concentration, structural properties, and the driving force, 14 independent replica exchange molecular dynamics simulations were performed in Aβ28 dimerization with and without Zn2+ (zAβ28) cooperation. Our scanning results show that the aggregation propensity is easier in Aβ28-Aβ28 and Aβ28-zAβ28 systems than zAβ28-zAβ28 system. In binding property, the Aβ28-Aβ28 model (−61.5 kcal mol−1) is stronger than zAβ28-zAβ28 (−26.6 kcal mol−1) and Aβ28-zAβ28 (−7.24 kcal mol−1) models. Further analysis confirmed that H13 and H14 residues play specific roles in the three systems. The key point is the orientation of N atom of the imidazole ring in histidine residues. Furthermore, we discovered different driving forces for each system. Our current study contributes to the understanding of how the Aβ28 dimer interacts with Zn2+, which could lead to new insights into Zn2+-induced nucleation mechanisms. 相似文献
259.
Linyan Yang Yamin Zong Lisha Yang Rui Lv Liyuan Jing Jifei Ma 《Journal of Coordination Chemistry》2017,70(12):2161-2173
One-pot solvothermal treatment of Co(NO3)2·6H2O, H2L (5-(3-methyl-5-(pyridin-4-yl)-4H-1,2,4-triazol-4-yl) isophthalic acid), and 4,4′-bipyridine (4,4′-bipy) in H2O/DMF (V/V = 1?:?1) yielded a cobalt-organic chain, [Co(L)(O)(H2O)2]n·1.25nH2O (1). Compound 1 as raw materials was calcined to obtain Co3O4, which could be confirmed by PXRD and SEM. Via the modification, Co3O4@SiO2-NH2 and Co3O4@SiO2-NH2-FA samples could be obtained. Compared to Co3O4@SiO2-NH2, Co3O4@SiO2-NH2-FA seems to have better peroxidase-mimetic properties. UV–vis results showed that optimal conditions of peroxidase-mimetic experiments were at 50°C in sodium acetate-acetic acid buffer (pH 3.6, 0.2 M), when the concentration of tetramethylbenzidine (TMB) was 0.2 mM. A concentration-dependent manner was shown between the concentration of glucose and absorbance in the measurement experiments for glucose. 相似文献
260.
沸石由于其低毒性和良好的生物相容性, 被认为是可用于医疗的新型生物材料. 本文综述了沸石与蛋白质的相互作用, 沸石以其离子交换、 表面性质以及可控孔道结构与蛋白质发生特异性结合或反应, 从而影响蛋白质的性能和行为; 重点讨论了其在生物医用领域的应用, 主要包括抗微生物材料和紧急止血材料两大应用; 分析了其在医学领域的独特优势, 特别是在止血应用领域; 最后对该领域面临的挑战和发展前景进行了总结与展望. 相似文献