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191.
A novel phenol-linked bis(imidazolium) salt, H3LCl2 (L = O-4-C(CH3)3-C6H2-2,6-di[CH2{C(NCHCH- NAr)}]2, Ar = 2,6-diisopropylphenyl, 1), was designed and used to prepare an ionic iron(III) complex [H2L][FeCl4] (2). Complex 2 was a highly efficient catalyst for aryl Grignard cross-coupling of alkyl chlorides bearing β-hydrogens. Furthermore, complex 2 was reusable and could be reused in at least eight times without significant loss in catalytic activity.  相似文献   
192.
The heating sources over the Tibetan Plateau (TP), the East Asian plain, and the western North Pacific (WNP) form a terraced thermal contrast in the west-east direction. Over East Asia and the WNP, this zonal thermal contrast contributes as high as 45 % to the seasonal variance based on the EOF analysis and exerts a significant impact on the seasonal transition of the East Asian climate through the enhancement of the year-round southerly to the southeast of the TP in late March and early April. This effect is investigated in this study using a high-resolution regional atmospheric model by doubling the surface sen- sible heat flux, respectively, over the TP, the East Asian plain, and the WNP in three sensitivity experiments. Comparisons among the experiments reveal that doubling the surface sensible heat flux over the WNP has little upstream response over East Asia. The increased zonal thermal contrast between the TP and the East Asian plain due to doubled heat flux over the TP would induce anomalous northerly over the region with year-round southerly to the southeast of the TP and weaken its seasonal enhancement. Doubling the surface sensible heat flux over the East Asian plain decreases the zonal thermal contrast and leads to southerly anomaly over the region with year-round southerly to the southeast of the TP and South China, which is favorable for the enhancement of the year-round southerly and its eastward extension.  相似文献   
193.
胰岛素粉末无针注射的给药效率和皮肤刺激性评价   总被引:1,自引:0,他引:1  
研究目的:胰岛素在临床上广泛用于糖尿病的治疗,但需要注射方式给药,给患者带来不便。本文报道了一种胰岛素粉末无针注射给药的新方法,并对其给药效率和皮肤刺激性进行评价。创新要点:首次报道了胰岛素粉末无针注射给药方法,有望为糖尿病患者长期自我给药提供便捷。研究方法:自主设计便携式自动无针粉末注射给药装置,采用计算机辅助方法计算给药装置的主要空气动力学参数;采用家兔评价无针粉末注射对皮肤的刺激性,并分析与空气动力学参数的相关性;采用四氧嘧啶诱导家兔糖尿病模型,评价不同无机盐载药的胰岛素粉末的无针注射给药降糖效果。重要结论:采用自主设计便携式自动无针粉末注射给药装置,递送以无机盐为载体的胰岛素粉末具有显著的降血糖作用,而递送胰岛素原料药粉末无降血糖作用,说明无机盐载体对胰岛素粉末无针注射给药效果具有重要作用。皮肤刺激性实验表明,储气室气压、容积以及喷管与皮肤的间距三个参数显著影响无针粉末注射装置的皮肤损伤程度,优化后的注射条件对皮肤几乎没有损伤。优化给药条件下以磷酸盐载体的胰岛素粉末无针注射给药,相对给药效率为72.25%。研究结果表明无针粉末注射技术用于胰岛素或其它生物制品的无针给药具有良好应用前景。  相似文献   
194.
Fluidized beds are nonlinear dynamic systems that exchange mass and energy with outside. They are governed not only by fluid dynamics, but by thermodynamics, especially the second law of thermodynamics as well. According to Prigogine's dissipative structure theory, the following have been concluded: (1) a fixed bed is on thermodynamic blanch, and bubbling, turbulent and fast beds are on the dissipatve structure branches. (2) Entropy in fluidized beds is divided into two parts: entropy production and entropy flux. The latter increases with gas velocity and decreases with pressure of the systems. That means the entropy of a system may reduce and the system with higher gas velocity behaves as dissipative structure characteristics. (3) For a given velocity, a fluidized bed operates stably on the whole, but it is unstable to local gas-solid phases. The unstable phases are described by fluid dynamic equations, While the minimum of system energy function assures whole stability of the system. (4) A transition criterion of a bubbling bed is derived from Prigogine's stability theory.  相似文献   
195.
A mathematical model for heat transfer during solidification in continuous casting of automobile steel, was established on researching under the influence of the solidifying process of bloom quality of CCM in the EAF steelmaking shop, at Shijiazhuang Iron and Steel Co. Ltd. Several steel grades were chosen to research, such as, 40Cr and 42CrMo. According to the results of the high temperature mechanical property tests of blooms, the respective temperature curves for controlling the solidification of different steels were acquired, and a simulating software was developed. The model was verified using two methods, which were bloom pinshooting and surface strand temperature measuring experiments. The model provided references for research on the solidifying process and optimization of a secondary cooling system for automobile steel. Moreover, it was already applied to real production. The calculated temperature distribution and solidification trend of blooms had offered a reliable theory for optimizing the solidifying process of blooms, increasing withdrawal speed, and improving bloom quality. Meanwhile, a new secondary cooling system was designed to optimize a secondary cooling water distribution, including choice and arrangements of nozzles, calculation of cooling water quantity, and so on.  相似文献   
196.
<正>As an important guarantee for human survival and development,the increasing use of mineral resources has led to the generation of a large amount of tailings and slags.However,with the deep promotion of green concepts such as solid waste resource utilization and sustainable development,adding additives to tailings as filling materials can not only improve resource utilization efficiency and prevent surface collapse,but also reduce solid waste discharge to the surface,which is an effectiv...  相似文献   
197.
198.
Shopsowitz KE  Qi H  Hamad WY  Maclachlan MJ 《Nature》2010,468(7322):422-425
Chirality at the molecular level is found in diverse biological structures, such as polysaccharides, proteins and DNA, and is responsible for many of their unique properties. Introducing chirality into porous inorganic solids may produce new types of materials that could be useful for chiral separation, stereospecific catalysis, chiral recognition (sensing) and photonic materials. Template synthesis of inorganic solids using the self-assembly of lyotropic liquid crystals offers access to materials with well-defined porous structures, but only recently has chirality been introduced into hexagonal mesostructures through the use of a chiral surfactant. Efforts to impart chirality at a larger length scale using self-assembly are almost unknown. Here we describe the development of a photonic mesoporous inorganic solid that is a cast of a chiral nematic liquid crystal formed from nanocrystalline cellulose. These materials may be obtained as free-standing films with high surface area. The peak reflected wavelength of the films can be varied across the entire visible spectrum and into the near-infrared through simple changes in the synthetic conditions. To the best of our knowledge these are the first materials to combine mesoporosity with long-range chiral ordering that produces photonic properties. Our findings could lead to the development of new materials for applications in, for example, tuneable reflective filters and sensors. In addition, this type of material could be used as a hard template to generate other new materials with chiral nematic structures.  相似文献   
199.
To effectively utilize ilmenite and recycle KOH solution, the extraction behaviours of titanium and other associated impurities in the decomposition process of ilmenite by highly concentrated KOH solution were studied. Experiments on the extraction behaviours of titanium as well as other associated impurities of ilmenite such as iron, silicon, calcium, and aluminium were carried out. The effects of various parameters, including reaction temperature, KOH concentration, reaction time, alkali-to-ore mass ratio, and particle size on the extraction rate of titanium and other impurities were examined. When the finely ground ore (58-75 μm) reacted with KOH solution (80wt%) in an alkali-to-ore mass ratio of 7:1 at 260℃ for 60 min, almost complete extraction of titanium was achieved, while the extraction rate of aluminium was 78% and that of other impurities was less than 22%. Moreover, high purity (98.2wt%) TiO2 with the anatase structure could be gained in the purification process.  相似文献   
200.
Reaction of homoleptic yttrium tris-alkyl complex YR3 (R=CH2C6H4NMe2-o) with 1 equivalent of amine bis(phenol)s LH2 (L=Me2NCH2CH2N(CH2-(2-O-C6H2-Bu^t 2-3,5))2) afforded the solvent-free yttrium alkyl complex LYR (1), which has been characterized with elemental analysis, 1H NMR and IR spectra, and structural determination. The coordination geometry around the center metal atom can be best described as a distorted octahedron. It was found that complex 1 can be used as an efficient catalyst for the Tishchenko reaction.  相似文献   
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