全文获取类型
收费全文 | 608篇 |
免费 | 24篇 |
专业分类
化学 | 422篇 |
晶体学 | 6篇 |
力学 | 6篇 |
数学 | 50篇 |
物理学 | 148篇 |
出版年
2024年 | 3篇 |
2023年 | 7篇 |
2022年 | 21篇 |
2021年 | 11篇 |
2020年 | 25篇 |
2019年 | 26篇 |
2018年 | 20篇 |
2017年 | 13篇 |
2016年 | 21篇 |
2015年 | 20篇 |
2014年 | 25篇 |
2013年 | 63篇 |
2012年 | 43篇 |
2011年 | 40篇 |
2010年 | 25篇 |
2009年 | 27篇 |
2008年 | 31篇 |
2007年 | 31篇 |
2006年 | 19篇 |
2005年 | 16篇 |
2004年 | 15篇 |
2003年 | 10篇 |
2002年 | 9篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 7篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 5篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1986年 | 8篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1977年 | 6篇 |
1976年 | 3篇 |
1975年 | 9篇 |
1974年 | 1篇 |
1971年 | 2篇 |
1970年 | 2篇 |
排序方式: 共有632条查询结果,搜索用时 15 毫秒
501.
Pathak A Rastogi S 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,67(3-4):898-909
Theoretical and experimental spectroscopic studies have underlined the contribution of large PAHs towards the astrophysical mid-infrared emission bands. Quantum chemical study of eight large PAHs using density functional theory approach is reported along with their infrared spectra. Systematic variation of bands with PAH size is noted and a better agreement with the observed astrophysical bands is obtained. Compared to small and medium sized PAHs there is substantial C-H stretch intensity in the cation spectra. This is attributed to smaller change in charge on the hydrogens upon ionization. For the C-H out-of-plane mode large PAHs correlate well with observed features on the shorter wavelength side of the 11.2 microm band. Presence of two sub-components of the broad 7.7 microm band in large PAHs compares very well with the corresponding astrophysical band and point to the abundance of large PAH cations in interstellar environments. The data presented here may be used for a more detailed study on the profile variations accompanying the mid-IR bands in various interstellar environments. 相似文献
502.
Kumar Shiny S. Rao Ankita Yadav K. K. Lenka R. K. Singh D. K. Tomar B. S. 《Journal of Radioanalytical and Nuclear Chemistry》2020,324(1):375-384
Journal of Radioanalytical and Nuclear Chemistry - Present study reports simultaneous batch and column extraction of Pu(IV) and Am(III) followed by selective stripping from actual analytical waste... 相似文献
503.
Nayana Adhikari Ankita Kashyap Anshul Shakya Surajit Kumar Ghosh Dibya Ranjan Bhattacharyya Hans Raj Bhat Udaya Pratap Singh 《Journal of heterocyclic chemistry》2020,57(6):2389-2399
A series of novel PABA-substituted 1,3,5-triazine derivatives were developed via microwave assisted synthesis and subsequently tested for antimalarial activity against chloroquine sensitive 3D7 strain of Plasmodium falciparum using chloroquine as standard. Antimalarial screening result showed that synthesized compounds exhibited IC50 in the range of 4.46 to 79.72 μg mL−1. Among the tested compounds, 4c and 4f showed significant antimalarial activity with low binding energies (BE) -172.32 and 160.41 kcal mol−1 via interacting with Arg122 through the involvement of COOH of the phenyl linked to 1,3,5-triazine. In conclusion, these core scaffolds can be used for future antimalarial drug development. 相似文献
504.
Sura Mallikarjun Reddy Bijivemula N. Reddy Venkata Krishna Reddy Motakatla Anusha Gokanapalli Madhvesh Pathak 《合成通讯》2019,49(16):1987-1996
A series of novel α-carboline derivatives such as 3-aryl-9H-pyrido[2,3-b]indole-6-sulfonamides have been synthesized from the readily available low-cost raw material, benzotriazole which is subjected to nucleophilic aromatic substitution with 5-bromo-2-chloropyridine followed by sequential steps of cyclization, sulfonation, amidation, and finally Suzuki–Miyaura coupling reactions. The C–C bond formation between 3-bromo-9H-pyrido[2.3-b]indole-6-sulfonamide and various boronic acids was achieved with more accessible palladium pre-catalyst, Pd-PEPPSI-IPr via Suzuki coupling under microwave condition in a short reaction time with excellent yields. 相似文献
505.
In recent years, heteroatom-incorporated specially structured metal-free carbon nanomaterials have drawn huge attention among researchers. In comparison to the undoped carbon nanomaterials, heteroatoms such as nitrogen-, sulphur-, boron-, phosphorous-, etc., incorporated nanomaterials have become well-accepted as potential electrocatalysts in water splitting, supercapacitors and dye-sensitized solar cells. This review puts special emphasis on the most popular synthetic strategies of heteroatom-doped and co-doped metal-free carbon nanomaterials, viz., chemical vapor deposition, pyrolysis, solvothermal process, etc., utilized in last two decades. These specially structured nanomaterials’ extensive applications as potential electrocatalysts are taken into consideration in this article. Their comparative enhancement of electrocatalytic performance with incorporation of heteroatoms has also been discussed. 相似文献
506.
507.
Lower‐ and Higher‐Order Nonclassical Properties of Photon Added and Subtracted Displaced Fock States
Priya Malpani Nasir Alam Kishore Thapliyal Anirban Pathak V. Narayanan Subhashish Banerjee 《Annalen der Physik》2019,531(2)
Nonclassical properties of photon added and subtracted displaced Fock states are studied using various witnesses of lower‐ and higher‐order nonclassicality. Compact analytic expressions are obtained for the nonclassicality witnesses. Using those expressions, it is established that these states and the states that can be obtained as their limiting cases (except coherent states) are highly nonclassical as they show the existence of lower‐ and higher‐order antibunching and sub‐Poissonian photon statistics, in addition to the nonclassical features revealed through the Mandel parameter, zeros of Q function, Klyshko's criterion, and Agarwal–Tara criterion. Further, some comparison between the nonclassicality of photon added and subtracted displaced Fock states have been performed using witnesses of nonclassicality. This has established that between the two types of non‐Gaussianity inducing operations (i.e., photon addition and subtraction) used here, photon addition influences the nonclassical properties more strongly. Further, optical designs for the generation of photon added and subtracted displaced Fock states from squeezed vacuum state have also been proposed. 相似文献
508.
Anindita Banerjee Kamal Patel Anirban Pathak 《International Journal of Theoretical Physics》2011,50(2):507-510
Recently Yang et al. (Int. J. Theor. Phys. 48:516, 2009) have shown that an unknown qubit can be teleported by using a particular GHZ-like state as quantum channel. However, there are several errors in the calculation which lead to incorrect conclusions. The errors
have been indicated and corrected. It is also noted that their scheme and the independently proposed teleportation scheme
of Zhang et al. (Int. J. Theor. Phys. 48:3331, 2009) uses quantum channel from the same family and any state of that family may be used for teleportation. 相似文献
509.
The effect of the presence of two probe waveguides on the dynamics of hyper-Raman processes is studied in terms of quantum Zeno and anti-Zeno effects. Specifically, the enhancement (diminution) of the evolution of the hyper-Raman processes due to interaction with the probe waveguides via evanescent waves is viewed as quantum Zeno (anti-Zeno) effect. This study considers the two probe waveguides interacting with only one of the optical modes at a time. For instance, as a specific scenario, it is considered that the two non-degenerate pump modes interact with each probe waveguide linearly, while Stokes and anti-Stokes modes do not interact with the probes. Similarly, in another scenario, it is assumed both the probe waveguides interact with Stokes (anti-Stokes) mode simultaneously. The present results show that quantum Zeno (anti-Zeno) effect is associated with phase-matching (mismatching). However, it do not find any relation between the presence of the quantum Zeno effect and antibunching in the bosonic modes present in the hyper-Raman processes. 相似文献
510.
Manorama Singh Smita R. Bhardiya Ambika Asati Harendra Sheshma Ankita Rai Vijai K. Rai 《Electroanalysis》2021,33(2):464-472
Herein, we report construction of a ferrocene-reduced graphene oxide-Mn spinel modified glassy carbon electrode (Fc−G/Mn3O4/GCE) as a sensitive electrochemical probe for hydrazine detection via its oxidation. The synergistic effect of ferrocene, graphene oxide and Mn3O4 provides it a great electrocatalytic effect. The electrochemical investigations of Fc−G/Mn3O4/GCE were studied using cyclic voltammetry, while differential pulse voltammetry was utilized for recording the electrocatalytic sensing of hydrazine. The prepared Fc−G/Mn3O4 offers a platform for sensitive and selective detection of low-level hydrazine in two linear ranges from 0.045 to 108 μM and 108 to 653 μM with limit of detection 8.5 nM. Real sample analysis was also performed in local industrial water samples with satisfactory recovery results. 相似文献