全文获取类型
收费全文 | 124篇 |
免费 | 19篇 |
国内免费 | 19篇 |
专业分类
化学 | 91篇 |
晶体学 | 1篇 |
力学 | 5篇 |
数学 | 5篇 |
物理学 | 60篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 11篇 |
2021年 | 5篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 4篇 |
2017年 | 6篇 |
2016年 | 7篇 |
2015年 | 7篇 |
2014年 | 1篇 |
2013年 | 4篇 |
2012年 | 7篇 |
2011年 | 11篇 |
2010年 | 3篇 |
2008年 | 4篇 |
2007年 | 5篇 |
2006年 | 7篇 |
2004年 | 3篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 7篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有162条查询结果,搜索用时 15 毫秒
91.
92.
利用考虑跨壳激发的投影壳模型(PSM)方法,研究了质子数Z=38、中子数N=63和64大形变丰中子101,102Sr同位素的结构性质。主要计算了转动谱、转动惯量和电磁跃迁性质等(如B(E2)和g因子),并与相应的实验数据进行系统比较和相关的理论预言。结果表明,PSM可以利用理论计算的能带图解释101,102Sr同位素的转动惯量、电磁跃迁随自旋的变化,分析晕带的结构。PSM理论可以很好地再现实验结果,说明PSM方法及其采用的有效相互作用可以外推研究丰中子核区101,102Sr同位素的原子核结构。对于101,102Sr同位素,核子开始填布质子g9/2和中子h11/2轨道,通过更为仔细地分析能带图中来自质子g9/2和中子h11/2轨道对各转动带的组态成分的贡献,清晰地表明丰中子核结构性质对不同核子填布的依赖。Recently, we have carried out systematically studies on the structural properties of proton number Z=38, neutron number N=63 and 64 neutron-rich isotopes 101,102Sr by using the projected shell model (PSM) with consideration of cross shell excitation. The rotation spectra, the moment of inertia and the electromagnetic transition properties (such as B(E2) and g-factor) are calculated and compared with the corresponding experimental data in this paper. Furthermore, more high spin states are predicted in the calculation and expected to be confirmed experimentally. The results show that the PSM can not only well analyze the structural properties of yrast bands in 101,102Sr but also interpret the variation of the moment of inertia, electromagnetic transition with spins in terms with the theoretical band diagram. The good agreement with the experimental data suggests that the PSM with the adopted effective interactions can be generalized to study the nuclear structure of 101,102Sr isotopes in neutron-rich mass region. For 101,102Sr isotopes, the nucleons begin to fill proton g9/2 and neutron h11/2 orbital, the dependence of nuclear structure and properties on the different orbital occupies is described by carefully analyzing the contribution from proton g9/2 and neutron h11/2 orbital to the configuration of rotational bands in band diagram. 相似文献
93.
A sensitive high-performance liquid chromatography (HPLC) method was developed to study the influence of ferulic acid on the formation of volatile fatty acids and lactic acid in milk and soybean milk samples. Volatile fatty acids were extracted by liquid–liquid micro-extraction using chloroform and acetonitrile as the extraction and disperser solvents, respectively. The analytes were derivatized with 2-(5-benzoacridine)ethyl-p-toluenesulfonate that showed excellent fluorescence property and made the sensitive HPLC analysis of short-chain fatty acids become possible. The optimized HPLC sensitivity was in the range of 1.1–1.9?µg?L?1. Ferulic acid was added in milk and soybean milk samples to study its preservative effect. The results indicated that ferulic acid with concentration of 0.2% (m/v) could effectively reduce the formation of short-chain fatty acids. 相似文献
94.
95.
Pengfei?Du Maojun?JinEmail author Ge?Chen Chan?Zhang Xueyan?Cui Yudan?Zhang Yanxin?Zhang Pan?Zou Zejun?Jiang Xiaolin?Cao Yongxin?She Fen?Jin Jing?WangEmail author 《Mikrochimica acta》2017,184(10):3705-3712
The authors have developed a competitive immunoassay for the model pesticide triazophos (TRIAZ). The method is based on the use of only one monoclonal antibody immobilized on multi-labeled gold nanoparticle (AuNP) probes. The immunoassay uses two sets of probe. The first is a multi-labeled AuNP probe that carries monoclonal antibody (mcAb), single-stranded DNA (ssDNA) and horse radish peroxidase (HRP). The second is a magnetic microparticle (MMP) probe that is obtained by coating MMPs with ovalbumin coupled to TRIAZ. Free TRIAZ and MMP-immobilized TRIAZ compete for binding to the mcAb on the surface of the AuNPs. Because TRIAZ is a rather small molecule, it cannot be bound by two antibodies. The competitive immunoassay overcomes the limitations of small molecule detection using one kind of mcAb only. Sensitive transduction of the immunoreaction is accomplished by enzymatically catalyzed amplified. TRIAZ was quantified by a conventional ELISA and by the immunoassay presented here. Both method are highly sensitive and well reproducible. The new assay has a linear response in the 15 ng L?1 to 40 μg L?1 TRIAZ concentration range, and a 14 ng L?1 limit of detection which make it more sensitive than the ELISA. The recovery rate in case of spiked samples ranges from 78.4 to 105%, and the RSD is <20%. A good correlation was further established between the results of the immunoassay and those of GC-MS analysis. 相似文献
96.
Wang C Zhu L Xiang J Yu Y Zhang D Shuai Z Zhu D 《The Journal of organic chemistry》2007,72(12):4306-4312
By coupling the features of binaphthalene and anthracene, new binaphthalenes with two anthracene moieties were designed and synthesized, aiming at developing chiral molecular switches. A strong CD signal with negative sign due to the interchromophoric exciton coupling was observed for (S)-1 with -(CH2)2 as the linker. This new CD signal became weak and the sign reversed by changing the linker to -(CH2)3 in (S)-2 and -(CH2)6 in (S)-3. For (S)-4 with -(CH2)11 as the linker, no such CD signal was detected. Photodimerization of two anthracene moieties in these binaphthalene molecules can occur. The results show that the CD spectra of (S)-1, (S)-2, (S)-3, and (R)-1 can be reversibly modulated by alternating UV light irradiation and heating. Therefore, chiral molecular switches based on new binaphthalenes with two anthracene moieties are achieved. 相似文献
97.
HL—1M装置等离子体电子温度测量 总被引:2,自引:2,他引:0
在HL-1M装置上用红宝石激光90o汤姆逊散射对等离子体电子温度进行了测量,建立了激光测量等离子体电子温度的数学模型。开发了用于数据采集和处理的程序,并对实验结果进行了初步讨论和误差分析。 相似文献
98.
单原子催化剂具有高原子利用率、高催化活性和高选择性等优点,兼具了均相催化剂“独立活性位点”和非均相催化剂“易循环利用”的特点,有效解决贵金属昂贵稀少的缺陷。其中载体不仅能影响单原子的稳定性,还影响其电子结构,从而影响催化性能。作为一种新型二维无机材料,MXene具有比表面积大、带隙可调、导电性好和螯合位丰富等特点,是制备单原子催化剂的理想载体材料。本文简要总结了MXene的结构特点,综述了MXene基单原子催化剂的制备策略,并着重介绍了MXene基单原子催化剂在电化学能源转换领域的应用,包括析氢反应、氧电极反应、氮还原反应、二氧化碳还原反应,以及在电池储能方面的应用。最后,总结了当前MXene基单原子催化剂在研究和实用方面所面临的挑战与机遇。 相似文献
99.
100.
流化床反应器中Ni/γ-Al2O3催化剂上甲烷部分氧化制合成气 总被引:5,自引:1,他引:4
催化甲烷部分氧化(POM)制合成气已成为替代水蒸气重整最有希望的工艺过程之一[1]. 该过程是个温和的放热反应,反应速度非常快,在高空速下可实现高甲烷转化,并且制得的合成气V(H2)/V(CO)=2, 可直接用于合成甲醇及F-T合成烃类、合成二甲醚等后续工业过程. 到目前为止,大部分POM的研究工作在固定床反应器中进行[2~4]. 由于反应速度极快,导致催化剂表面存在热点[2,5], 不仅影响实验的准确性[6,7], 而且工业应用困难. 热点的存在还会导致活性组分Ni的烧结和流失. 在固定床反应器中,催化剂积炭也是导致其活性下降的重要原因[8,9]. Bharadwaj等[10]发现,流化床反应器Rh和Ni催化剂上甲烷转化率高达90%, 反应后催化剂未发现积炭. Santos等[11]曾报道采用流化床催化剂床层几乎可以实现等温分布,而且甲烷转化率接近热力学平衡值, 反应10 h后催化剂表面积炭量仅为0.6%. 本文采用流化床反应器考察了不同反应条件下Ni/γ-Al2O3催化剂上甲烷部分氧化的反应性能,同时对催化剂积炭及稳定性作了初步研究. 相似文献