全文获取类型
收费全文 | 172篇 |
免费 | 13篇 |
国内免费 | 21篇 |
专业分类
化学 | 107篇 |
力学 | 10篇 |
数学 | 39篇 |
物理学 | 50篇 |
出版年
2023年 | 6篇 |
2022年 | 9篇 |
2021年 | 4篇 |
2020年 | 10篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 1篇 |
2015年 | 7篇 |
2014年 | 8篇 |
2013年 | 21篇 |
2012年 | 22篇 |
2011年 | 21篇 |
2010年 | 21篇 |
2009年 | 18篇 |
2008年 | 7篇 |
2007年 | 11篇 |
2006年 | 10篇 |
2005年 | 5篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有206条查询结果,搜索用时 15 毫秒
171.
Chao-Yong Mang Yu Zhao Hai-Feng Li Hai Lan Ya Yan Ming-Hui Yang 《Molecular physics》2013,111(1):104-112
The density functional theory (DFT) is exploited to search the stable conformations of a cyclic pentapeptide called cycloaspeptide G from Cordyceps-colonising fungus Isoria farinose. Its time-dependent version is employed to describe the profiles of electronic circular dichroism (ECD) of the preferred conformation, where the solvent effect in methanol is taken into account on the basis of the polarisable continuum model computation. Four stable conformers are optimised, and the results of the harmonically vibrational frequency calculations illustrate that they are the true minima. In the vibrational CD spectrum at the B3LYP/6-31G* level, the negative peak at 3334 cm?1 has its origin of the NH stretches of the peptide ring. In the ECD spectrum at the B3LYP/6-31G* level, three strong bands are negative, positive, and negative. Since the ECD spectrum at the B3LYP/6-31G* level is remarkably different from that at the B3LYP/6-31G level, it is necessary for the expended functions to be added to the 6-31G basis set. 相似文献
172.
Long-Jye Sheu Hsien-Keng Chen Juhn-Horng Chen Lap-Mou Tam 《Chaos, solitons, and fractals》2007,31(5):1203-1212
The dynamics of fractional-order systems have attracted a great deal of attentions in recent years. With fractional order, the dynamics of a system which includes comprehensive dynamical behaviors, such as fixed point, periodic motion, chaotic motion, and transient chaos is studied numerically in this paper. It is known that chaos exists in the fractional-order system with order less than 3. In this study, the lowest order found for this system to yield chaos is 2.43. The results are validated by the existence of a positive Lyapunov exponent. Period doubling routes to chaos in the fractional-order system are also obtained. Moreover, generation of a four-scroll chaotic attractor by the system is observed. 相似文献
173.
Allele frequency of 19 autosomal STR loci in the Bai population from the southwestern region of mainland China
下载免费PDF全文
![点击此处可从《Electrophoresis》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yi Li Yine Hong Xiujiang Li Jinmeng Yang Lanjiang Li Ying Huang Chuanchao Wang Hui Li Bingying Xu 《Electrophoresis》2015,36(19):2498-2503
The aim of this study was to investigate a 19 STR loci database using the Bai population from China. This multiplex amplification kit included 13 CODIS STR markers and six plus STR markers (D19S433, Penta E, D2S1338, Penta D, D6S1043, and D12S391) that were successfully analyzed by using 1158 DNA samples from the Bai population from the southwestern part of mainland China. These results indicate that this multiplex amplification kit may provide significant polymorphic information for kinship testing and relationship investigations. 相似文献
174.
以2,6-二(5-甲基-1H-吡唑-3-基)吡啶(简写为H2L)为第一配体,以均苯四甲酸和乙酸为第二配体,合成了2个新的配位超分子化合物[Ni(H2L)2]·(Me O-H2BTA)2(1)和Mn(H2L)(Ac)2(2)(H4BTA∶均苯四甲酸,HAc∶乙酸),并由元素分析、红外光谱、紫外-可见光谱以及X射线单晶衍射等对其进行了表征,分析了其光谱及结构特征。晶体结构分析表明,化合物1属于正交晶系,Pbcn空间群,a=0.95747(8)nm,b=1.99273(13)nm,c=2.50175(13)nm,α=90°,β=90°,γ=90°,V=4.773 3(6)nm3,Z=4;化合物2属于单斜晶系,Cc空间群,a=1.11300(13)nm,b=2.0239(2)nm,c=0.97308(12)nm,α=90°,β=118.555(16)°,γ=90°,V=1.9253(4)nm3,Z=4。 相似文献
175.
Xinming Li Donglei Shi Yihe Song Yixiang Xu Ying Gao Wenjing Qiu Xin Chen Xiaokang Li Yunyuan Huang Yanjun Feng Baoli Li Yuan Guo Jian Li 《中国化学快报》2022,33(3):1572-1576
Monoamine oxidase A(MAO-A) is a prominent myocardial source of reactive oxygen species(ROS), and its expression and activity are strongly increased in failing hearts. Therefore, accurate evaluation of MAOA activity in cardiomyocytes is of great importance for understanding its biological functions and early diagnosing the progression of heart failure. However, so far, there is no report on the fluorescent diagnosis of heart failure by a specific probe for MAO-A. In this work, two far-red emissiv... 相似文献
176.
Two new labdane diterpenoids, s-trans-8(17),12E,14-labdatrien-20-oic acid (1), s-trans-12E,14-labdadien-20,8β-olide (2), along with 10 known compounds, hinokiol (3), ursonic acid (4), 2α,3α-dihydroxyolean-12-en-28-oic acid (5), 2α,3β,23-trihydroxyolean-12-en-28-oic acid (6), ethyl 3-(3,4-dihydroxyphenyl)lactate (7), ethyl rosmarinate (8), (Z,E)-2-(3,4-dihydroxyphenyl)ethenyl caffeic ester (9), tridecanoic acid (10), β-sitosterol (11) and daucosterol (12), were isolated from the 70% acetone extract of the rhizomes of Isodon yuennanensis. Their structures were elucidated based on the analyses of extensive spectroscopic data and physicochemical properties. 相似文献
177.
医院管理综合评价方法的组合与优化 总被引:1,自引:0,他引:1
针对医院管理中单一综合评价方法的不足,基于评价结果的一致性和评价方法的兼容性对四种评价方法进行比较、组合和优化,提出一种改进的平均值组合方法.使其评价结果更合理,兼容性更高. 相似文献
178.
179.
180.
《Journal of magnetism and magnetic materials》2001,224(2):162-166
Single crystals of Nd0.7Pb0.3MnO3 with large crystal size were obtained by the flux growth. The temperature dependence of the resistivity and magnetoresistance was measured. It has been discovered that a phase transition occurs from a ferromagnetic-metal (FM) to a ferromagnetic-insulator (FI) phase at 120 K, below the Curie temperature. At the Curie temperature, the samples exhibit a larger value of magnetoresistance (MR) than polycrystalline samples. The second peak of the magnetoresistance has been observed on MR(T) curve below the Curie temperature. The transition properties and magnetoresistance behavior were discussed. 相似文献