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51.
激光测微法研究双(对甲苯磺酸)-2,4-已二炔-1,6-二醇酯的固态热聚合 总被引:1,自引:0,他引:1
用激光测微法跟踪了双(对甲苯磺酸)-2,4-己二炔-1,6-二醇酯(TS)固态晶相热聚合时宏观尺寸的变化,由此推算TS聚合时晶胞参数的变化。结果表明,在形成聚合物PTS大分子链的c轴方向上一直收缩,而在横向a、b方向上则是先膨胀后收缩。 相似文献
52.
建立了谷物和动物饲料中霉菌毒素的高效、快速前处理方法,可同时提取和净化样品中37种理化性质差异较大的霉菌毒素,并采用超高效液相色谱-串联质谱(UPLC-MS/MS)进行定性和定量分析。样品粉碎处理后,经84%(体积分数,下同)乙腈水(含0.1%甲酸)溶液振荡提取20 min,MLJ-1杂质吸附型固相萃取柱净化。目标物在BEH RP18色谱柱上分离,以0.1 mmol/L乙酸铵溶液(含0.1%甲酸)和甲醇溶液(含0.1%甲酸)作为流动相进行梯度洗脱,质谱采用电喷雾正、负离子模式和多反应监测模式进行定性和定量分析。结果表明,本方法可在1 min内完成样品净化处理,15 min内完成37种目标化合物的分离分析。37种目标物在各自线性范围内线性关系良好,基质匹配标准曲线的相关系数均大于0.98。除伏马毒素外的所有目标化合物在4个添加水平下的回收率介于80%~120%之间,相对标准偏差(RSD)<20%(n=5),方法定量限为2~40 μg/kg,能够满足《饲料卫生标准》判定要求。该方法操作简单、快速、准确,适合谷物和动物饲料中多种霉菌毒素同步筛查和确证检测。 相似文献
53.
采取355 nm激光脉冲辐照熔石英样品,利用Nomarski微分干涉差显微镜、原子力显微镜和扫描电子显微镜观测手段对前后表面产生的损伤点进行了观察分析。对前后表面损伤形态做出详细的描述和分类,从理论上对每种损伤类型产生的条件与机理做出推测。实验结果表明:熔石英前表面存在小麻点群损伤和星状裂纹损伤两种损伤形态,横向尺寸分别为0.8~2.5和1.0~5.5 μm;后表面存在小麻点群损伤、壳状剥离损伤和火山口3种损伤形态,损伤横向尺寸分别为0.48~1.33,4~20和12~30 μm。实验证明了1 μm尺度损伤点的产生与再沉积层密切相关。 相似文献
54.
Linjie Feng Liwei Wang Zhichao Hu Yuan Tian Yuezhong Xian Litong Jin 《Mikrochimica acta》2009,164(1-2):49-54
A biohybrid hydrogel is fabricated by integrating horseradish peroxidase (HRP) with polyhydroxyl cellulose (PHC), which is prepared by mixing of poly(vinyl alcohol) and carboxymethyl hydroxyethyl cellulose. PHC provides a biocompatible microenvironment for HRP, and the UV-vis spectrum indicates that the confromation of HRP-loaded biohydrogel is well retained relative to free HRP. Based on the direct electrochemistry and electrocatalytic ability of HRP, a third-generation H2O2 biosensor is developed. Under the optimized conditions, the H2O2 biosensor shows a linear response over the range from 1.0 μM to 1.0 mM with a detection limit (S/N?=?3) of 0.5 μM. 相似文献
55.
Zhichao Shan Xinping Lin Minling Liu Hanming Ding Fuqiang Huang 《Solid State Sciences》2009,11(6):1163-1169
A novel visible-light-driven layered photocatalyst of Bi-based PbBiO2Cl is prepared by solid-state reaction. The optical band gap of PbBiO2Cl is determined to be 2.45 eV by UV–vis diffuse reflectance spectroscopy. Generally, the photocatalytic activity for degrading methyl orange (MO) over PbBiO2Cl is higher than that over anatase-type TiO2 under UV light and visible light illumination. The RuO2 loading over PbBiO2Cl leads to an obvious increase in photocatalytic performance. The internal electric fields between [PbBiO2] and [Cl] slabs are considered to be useful for the efficient separation of electron–hole pairs upon photoexcitation. 相似文献
56.
Liwei Wang Yuan Tian Qin Ran Zhichao Hu Jingjing Xu Yuezhong Xian Ru Peng Litong Jin 《Electrochemistry communications》2009,11(2):339-342
In this paper, we described a simple and facile method for the covalent functionalization of Au surface with nitrophenyl group via stepwise strategy. Structurally well-defined azide-terminated organic self-assembled monolayers (SAMs) were formed on Au surface from a commercially available mixture solution of azidoundecanethiol and dilute thiol. Subsequent, derivatization of the azide-terminated monolayers was conducted in aqueous environments with ethynyl nitrobenzene via a selective, reliable, robust click reaction. By this way, the nitrophenyl group was covalently and quantitatively grafted on Au surface, which was confirmed by Raman Spectrometry and electrochemical methods. These results demonstrated the efficiency of using click chemistry in assembling covalently linked nanostructures. 相似文献
57.
[reaction: see text] The Lattrell-Dax method of nitrite-mediated substitution of carbohydrate triflates is an efficient method to generate structures of inverse configuration. In the present study, epimerization of gluco- and galactopyranoside derivatives to the corresponding allo- and gulopyranoside structures by triflation/nitrite treatment has been investigated. It was found that a neighboring ester group was essential for the reactivity of the nitrite-mediated triflate inversion. Furthermore, a good inversion yield also depended on the relative configuration of the neighboring ester group to the triflate. Only with the ester group in the equatorial position, whatever the configuration of the triflate, did the reaction proceed smoothly, whereas a neighboring axial ester group proved largely inefficient. The results were subsequently used to predict the inversion of glucopyranoside derivatives to the mannopyranoside epimers. 相似文献
58.
59.
基于密度泛函理论的第一性原理方法,系统研究了三元金属间化合物SrAlSi在高压下的电子性质和晶格动力学性质.三元金属间化合物SrAlSi具有和MgB2类似的六角蜂巢状结构,Sr原子取代了Mg原子的位置,Al、Si原子无序地占据B原子的位子.通过对SrAlSi三元金属间化合物能带和三维费米面的计算,发现在压力的作用下SrAlSi费米面附近的能带发生电子拓扑变化,压力可以导致电子拓扑结构相变(ETTs).通过晶格动力学研究发现,在压力的作用下,SrAlSi的光学支沿着A-L-H方向逐渐软化,声学支逐渐变硬,说明金属间化合物SrAlSi在压力作用下结构不是很稳定,随着压力的继续增大,会有新的结构出现. 相似文献
60.