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Systematic study on α-decay half-lives of uranium isotopes with a screened electrostatic barrier 下载免费PDF全文
Yang-Yang Xu De-Xing Zhu You-Tian Zou Xi-Jun Wu Biao He Xiao-Hua Li 《中国物理C(英文版)》2022,46(11):114103-114103-9
In the present work, we systematically study the α-decay half-lives of uranium (Z=92) isotopes based on the Gamow model with a screened electrostatic barrier. There are only two adjustable parameters in our model i.e. the parameter g and the screening parameter t in the Hulthen potential for considering the screened electrostatic effect of the Coulomb potential. The calculated results are in good agreement with experimental data, and the corresponding root-mean-square (rms) deviations of uranium isotopes with α transition orbital angular momentum l=0 and l=2 are 0.141 and 0.340, respectively. Moreover, we extend this model to predict α-decay half-lives of uranium isotopes whose α decay is energetically allowed or observed but not yet quantified in NUBASE2020. For comparison, the modified Hatsukawa formula (XLZ), the unified Royer formula (DZR), the universal decay law (UDL) and the Viola–Seaborg–Sobiczewski formula (VSS) are also used. The predictions are basically consistent with each other. Meanwhile, the results also indicate that N=126 shell closure is still robust at Z=92 and the spectroscopic factor \begin{document}$ S_{\alpha} $\end{document} ![]()
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is almost the same for uranium isotopes with the same l. 相似文献
3.
本文考虑了受L\''evy噪声扰动的Logistic方程. 在合适的条件下, 我们得到了解的全局存在性与唯一性; 我们证明了当初始值小于环境的容纳量时, 唯一的正的平衡态具有全局吸引性. 相似文献
4.
对于原电池,电极电势的本质是化学体系对电极材料上电子势能的影响,其正负极电势差反映化学能向电能转化的趋势。电极界面上化学物质的氧化/还原反应是通过何种途径影响到电极上电子势能的,现有的教材和论著没有给出明确的解释。本文基于相间电化学势平衡原则阐明了固液界面上离子平衡与电极上电子电势的关系,并由此给出了标准电势的物理含义:它是构成电极体系一系列物性参数的组合,包括被测电极的电子、离子化学势,工作电极电解液的离子化学势,参比电极的电子、离子化学势和参比电极电解液的离子化学势等。 相似文献
5.
建立了水产品中11种海洋生物毒素的高效液相色谱-四极杆/静电场轨道阱高分辨质谱(HPLC-Q-Orbitrap HRMS)检测方法。该方法采用分级提取原理,结合分散固相萃取技术(dSPE)和载体辅助液液萃取技术(SLLE),建立了对亲水性及亲脂性海洋生物毒素的"一站式"提取净化体系。在优化条件下,11种毒素在一定质量浓度范围内具有良好的线性关系,相关系数(r)均大于0.99。该方法对11种毒素的检出限为1~10μg/kg,定量下限为2~20μg/kg,加标回收率为55.6%~122%,相对标准偏差为5.4%~16%。方法快速高效,可操作性强,解决了不同理化性质的海洋生物毒素的通用性检测问题,可满足水产品中海洋生物毒素的快速筛查要求。 相似文献
6.
Prof. Sławomir J. Grabowski 《Chemphyschem》2019,20(4):565-574
ωB97XD/aug-cc-pVTZ calculations were performed for complexes of dihydrogen, cyclopropane, cyclobutane and cyclopentane, with simple proton donating species such as hydrogen fluoride, hydrogen chloride, water, hydrogen cyanide and acetylene. Numerous dependencies between geometrical, energetic and topological parameters of complexes considered were found, since various theoretical approaches were applied: Quantum Theory of ‘Atoms in Molecules’ (QTAIM), Natural Bond Orbital (NBO) method and energy decomposition analysis (EDA). It was confirmed that complexes of dihydrogen and cyclopropane are linked through the A−H…σ interactions that may be classified as hydrogen bonds. In the case of complexes of cyclobutane such hydrogen bonds are rather weak. Other type and also weak A−H…C hydrogen bonds are formed for complexes with cyclopentane. 相似文献
7.
气敏传感器具有气体识别、探测和监测等功能, 广泛应用于工业生产等领域, 但在泄漏预警时缺乏迅速识别和定位等功能. 本文基于传感器制备工艺偏差分析, 通过对传感器气敏机制的研究, 提出一种基于Ni-SnO2纳米颗粒的气敏传感器物理不可克隆函数(Gas Sensor-Physical Unclonable Function, GS-PUF)设计方案. 该方案利用掺杂Ni元素的方法, 结合静电喷雾沉积技术制备Ni-SnO2气敏传感器, 以获取更加稳定可靠的物理特征值, 然后采集气敏传感器对不同浓度下气体的响应数据, 最后利用随机阻值多位平衡算法比较不同组气敏传感器响应电信号值, 实现PUF数据输出. 制备每组样本可产生128位二进制数据的多组PUF样本, 进行对比实验. 结果表明, 所设计的GS-PUF具有气体泄漏源头识别定位的功能, 且随机性提升至99%, 唯一性达49.80%. 相似文献
8.
Joanna Bojarska Milan Remko Izabela D. Madura Krzysztof Kaczmarek Janusz Zabrocki Wojciech M. Wolf 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(4):328-345
Recently, fluorenylmethoxycarbonyl (Fmoc) amino acids (e.g. Fmoc–tyrosine or Fmoc–phenylalanine) have attracted growing interest in biomedical research and industry, with special emphasis directed towards the design and development of novel effective hydrogelators, biomaterials or therapeutics. With this in mind, a systematic knowledge of the structural and supramolecular features in recognition of those properties is essential. This work is the first comprehensive summary of noncovalent interactions combined with a library of supramolecular synthon patterns in all crystal structures of amino acids with the Fmoc moiety reported so far. Moreover, a new Fmoc‐protected amino acid, namely, 2‐{[(9H‐fluoren‐9‐ylmethoxy)carbonyl](methyl)amino}‐3‐{4‐[(2‐hydroxypropan‐2‐yl)oxy]phenyl}propanoic acid or N‐fluorenylmethoxycarbonyl‐O‐tert‐butyl‐N‐methyltyrosine, Fmoc‐N‐Me‐Tyr(t‐Bu)‐OH, C29H31NO5, was successfully synthesized and the structure of its unsolvated form was determined by single‐crystal X‐ray diffraction. The structural, conformational and energy landscape was investigated in detail by combined experimental and in silico approaches, and further compared to N‐Fmoc‐phenylalanine [Draper et al. (2015). CrystEngComm, 42 , 8047–8057]. Geometries were optimized by the density functional theory (DFT) method either in vacuo or in solutio. The polarizable conductor calculation model was exploited for the evaluation of the hydration effect. Hirshfeld surface analysis revealed that H…H, C…H/H…C and O…H/H…O interactions constitute the major contributions to the total Hirshfeld surface area in all the investigated systems. The molecular electrostatic potentials mapped over the surfaces identified the electrostatic complementarities in the crystal packing. The prediction of weak hydrogen‐bonded patterns via Full Interaction Maps was computed. Supramolecular motifs formed via C—H…O, C—H…π, (fluorenyl)C—H…Cl(I), C—Br…π(fluorenyl) and C—I…π(fluorenyl) interactions are observed. Basic synthons, in combination with the Long‐Range Synthon Aufbau Modules, further supported by energy‐framework calculations, are discussed. Furthermore, the relevance of Fmoc‐based supramolecular hydrogen‐bonding patterns in biocomplexes are emphasized, for the first time. 相似文献
9.
Parameterization of electrostatic interactions for molecular dynamics simulations of heterocyclic polymers 下载免费PDF全文
Victor M. Nazarychev Sergey V. Larin Alexander V. Yakimansky Natalia V. Lukasheva Andrey A. Gurtovenko Iosif V. Gofman Vladimir E. Yudin Valentin M. Svetlichnyi Jose M. Kenny Sergey V. Lyulin 《Journal of Polymer Science.Polymer Physics》2015,53(13):912-923
The paper focuses on the problem of electrostatic interactions in molecular dynamics simulations of thermal properties of heterocyclic polymers. The study focuses on three thermoplastic polyimides synthesized on the basis of 1,3‐bis‐(3′,4‐dicarboxyphenoxy)benzene (dianhydride R) and three diamines: 4,4′‐bis‐(4″‐aminophenoxy) diphenylsulfone (diamine BAPS), 4,4′‐bis‐(4″‐aminophenoxy) biphenyl (diamine BAPB), and 4,4′‐bis‐(4''‐aminophenoxy) diphenyloxide (diamine BAPO). In the molecular dynamics simulations these polyimides were described by the Gromos53a5 force field. To parameterize the electrostatic interactions four methods of calculating the partial atomic charges were chosen: B3LYP/6–31G*(Mulliken), AM1(Mulliken), HF/6–31G*(Mulliken), and HF/6–31G*(ChelpG). As our parameterization is targeted to reproduce thermal properties of the thermoplastic polyimides, the choice of proper partial charges was finalized on a basis of the closest match between computational and experimental data for the thermal expansion coefficients of the polyimides below glass transition temperatures. Our finding clearly show that the best agreement with experimental data is achieved with the Mulliken partial atomic charges calculated by the Hartree‐Fock method with 6–31G* basis set. Furthermore, in addition to the thermal expansion coefficients this set of partial atomic charges predicts an experimentally observed relationship between glass transition temperatures of the three polyimides under study: . A mechanism behind the change in thermal properties upon the change in the chemical structure in considered polyimides may be related to an additional spatial ordering of sulfone groups due to dipole‐dipole interactions. Overall, the modified force‐field is proved to be suitable for accurate prediction of thermal properties of thermoplastic polyimides and can serve as a basis for building up atomistic theoretical models for describing other heterocyclic polymers in bulk. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 912–923 相似文献
10.
Molecular dynamic study of dielectric polarization and ferroelectricity in a model polar polymer 下载免费PDF全文
Jeffrey P. Calame 《Journal of Polymer Science.Polymer Physics》2015,53(10):740-759
Molecular dynamics simulations are used to explore the polarization response of a lamellar crystal consisting of folded chains of a highly simplified model polar polymer. The system is based on a united atom model of polyethylene with constrained bond lengths and bond angles, and it is endowed with artificial partial charges placed on the united atoms to give it a simple polar character. Simulations performed with various temperatures, electric field directions, and electric field application histories reveal a complicated sequence of reorientation processes, including pronounced ferroelectric behavior. The sequence includes a weak, temperature‐independent prompt response, and a slow‐rising delay regime with stretched exponential behavior and thermally‐activated reorientation parameters consistent with trans‐gauche (TG) barrier crossings in the amorphous phase. When the delay regime has progressed sufficiently, a primary large‐amplitude response due to organized rotation of large subsegments in the crystalline phase occurs in a rapid manner that requires relatively few TG barrier crossings. A final, extremely slow rise in residual polarization completes the sequence. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 740–759 相似文献