全文获取类型
收费全文 | 1578篇 |
免费 | 56篇 |
国内免费 | 15篇 |
专业分类
化学 | 1001篇 |
晶体学 | 27篇 |
力学 | 57篇 |
数学 | 233篇 |
物理学 | 331篇 |
出版年
2023年 | 10篇 |
2022年 | 49篇 |
2021年 | 45篇 |
2020年 | 45篇 |
2019年 | 53篇 |
2018年 | 55篇 |
2017年 | 57篇 |
2016年 | 72篇 |
2015年 | 55篇 |
2014年 | 69篇 |
2013年 | 162篇 |
2012年 | 98篇 |
2011年 | 134篇 |
2010年 | 78篇 |
2009年 | 86篇 |
2008年 | 98篇 |
2007年 | 97篇 |
2006年 | 66篇 |
2005年 | 56篇 |
2004年 | 46篇 |
2003年 | 42篇 |
2002年 | 33篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 5篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 11篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 9篇 |
1992年 | 10篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 10篇 |
1983年 | 3篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1977年 | 2篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1967年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有1649条查询结果,搜索用时 15 毫秒
61.
The Ising model with three alternative layers on the honeycomb and square lattices is studied by using the effective-field theory with correlations. We consider that the nearest-neighbor spins of each layer are coupled ferromagnetically and the adjacent spins of the nearest-neighbor layers are coupled either ferromagnetically or anti-ferromagnetically depending on the sign of the bilinear exchange interactions. We investigate the thermal variations of the magnetizations and present the phase diagrams. The phase diagrams contain the paramagnetic, ferromagnetic and anti-ferromagnetic phases, and the system also exhibits a tricritical behavior. 相似文献
62.
Gulsah Saydan Kanberoglu Erkan Yilmaz Mustafa Soylak 《Journal of the Iranian Chemical Society》2018,15(10):2307-2314
In this study, we used deep eutectic solvents for digestion and ultrasound-assisted emulsification liquid phase microextraction (UA-ELPME) of copper in liver samples. Different types of DESs were prepared for digestion and microextraction steps. DESs consisting of lactic acid and choline chloride for the digestion step and DESs consisting of tetrabuthylamonium chloride and decanoic acid for ultrasound-assisted emulsification liquid phase microextraction were used in this method. The liver samples were digested by using DES-based digestion method. After digestion step, Cu(II) ions in aqueous phase were complexed with sodium dimethyl dithiocarbamate (NaDMDTC) and the obtained hydrophobic complex was extracted to tetrabuthylamonium chloride-decanoic acid DES phase. A microsample injection system coupled with flame atomic absorption spectrometer (MS-FAAS) was used in the detection of copper. LOD, LOQ, PF and % RSD were determined as 4.00, 13.2 µg L??1, 10 and 3.2%, respectively. The proposed microextraction procedure was successfully applied to copper contents of the liver samples. 相似文献
63.
Lgaz Hassane Chaouiki Abdelkarim Albayati Mustafa R. Salghi Rachid El Aoufir Yasmina Ali Ismat H. Khan Mohammad I. Mohamed Shaaban K. Chung Ill-Min 《Research on Chemical Intermediates》2019,45(4):2269-2286
Research on Chemical Intermediates - Mild steel corrosion in HCl solution is an example of corrosion in acidic mediums. The ongoing research efforts to develop novel environmentally friendly... 相似文献
64.
Cesme Mustafa Polat Duygu Senel Pelin Golcu Aysegul 《Russian Journal of Electrochemistry》2019,55(4):281-290
Russian Journal of Electrochemistry - In this study, a new biosensor for amisulpride (ASP) determination is defined. The interaction between ASP and fish sperm double-stranded DNA (FSdsDNA) was... 相似文献
65.
Ghommem Mehdi Najar Fehmi Arabi Mohamed Abdel-Rahman Eihab Yavuz Mustafa 《Nonlinear dynamics》2020,101(1):271-291
Nonlinear Dynamics - We present a unified model of electrostatic sensors comprising cantilever microbeam resonators in fluid media. The model couples Euler–Bernoulli beam equation to the... 相似文献
66.
Abdul Q. Ramle Asli Karakas Abdul K. M. Arof Mustafa Karakaya Mehmet Taser Aysun Gozutok Chee Chin Fei Nurhidayatullaili M. Julkapli Wan J. Basirun 《Journal of heterocyclic chemistry》2020,57(10):3566-3573
Two new macrocyclic dibenzotetraaza[14]annulene (DBTAA) compounds with indolenine ( 5 ) and pyridoindolenine ( 6 ) moieties were synthesized and characterized by spectroscopy. Both DBTAAs exhibit strong UV-Vis absorption properties in the Soret band region. The theoretical second-order nonlinear optical property, electric dipole moment (μ), dispersion-free dipole polarizability (α) and first hyper-polarizability values were calculated by density functional theory and time dependent density functional theory. The ab-initio quantum mechanical calculation by time-dependent Hartree-Fock method was utilized to investigate the dynamic dipole polarizabilities, dynamic second-order, static, and dynamic third-order (γ) hyper-polarizabilities of the DBTAAs. The configuration interaction technique of all doubly occupied molecular orbitals possesses theoretically defined single-photon absorption (OPA) specifications for the examined structures. The computed maximum OPA wavelengths on both macrocyclic compounds coincide with the preceding measurement outcomes. 相似文献
67.
Mustafa A. S. Gouda Mounir A. I. Salem Naglaa F. H. Mahmoud 《Journal of heterocyclic chemistry》2020,57(11):3988-4006
Some poly functionalized heterocyclic-compounds containing pyridine-moieties were readily assembled by combining differently functionalized pyridopyrimidine-6-carbonitrile derivatives 1a,b with different electrophilic and nucleophilic reagents via short synthetic routes. The structures of the prepared derivatives were ascertained from their-spectral-and elemental analyses. Some of the synthesized compounds were tested as plausible antitumor agents. Most of those tested compounds likes 7 , 9 , 10 , 11a showed cytotoxic potencies against different tumor cell lines. In addition, the assessments for their antioxidant activities have also been done and compound 9 exhibited the highest antioxidant activity while compounds 7 and 10 showed moderate activities. Finally, molecular docking studies were carried out which favorably indicated a high support for the experimental-results. 相似文献
68.
Plasma Chemistry and Plasma Processing - In this study, thin films of poly(cyclohexyl methacrylate) (PCHMA) were deposited on silicon wafer using PECVD technique, in which the plasma power is... 相似文献
69.
In this study, an ITO (indium tin oxide) based biosensor was constructed to detect SOX2. SOX2 helps the regulation of cell pluripotency and is closely related to early embryonic development, neural and sexual differentiation. SOX2 is amplified and overexpressed in some malignant tumors such as squamous cell, lung, prostate, breast, esophageal cell, colon, ovarian, glioblastoma, pancreatic cancer, gastric cancer, head and neck squamous cell carcinoma. To generate a hydroxylated clean electrode surface, ITO electrodes were treated with NH4OH/H2O2/H2O. Later, ITO‐PET electrode surfaces were modified with 3‐glycidoxypropyl trimethoxysilane (3‐GOPS). Then, Anti‐SOX2 was covalently immobilized onto the electrode surfaces. 3‐GOPS concentration, Anti‐SOX2 concentration and incubation time, SOX2 incubation time were optimized. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were utilized in order to follow up the immobilization processes and the optimization steps of the biosensor. To characterize the analytical properties of constructed immunosensor; linear range, repeatability, reproducibility and regeneration studies were investigated. The linear range of the immunosensor was detected as 0.625 pg/mL–62.5 pg/mL. Square wave voltammetry technique was also applied to the biosensor. Storage life of the biosensor was determined for identifying the possible usability of the biosensor in clinical field. Finally, the designed biosensor was applied to the real human serum samples. The results obtained with the presented biosensor were also compared with ELISA results. 相似文献
70.
Ziya CAN Büra KESKN Ayem ARDA Erol ERA Mustafa Reat APAK 《Turkish Journal of Chemistry》2020,44(5):1366
Excessive amounts of reactive oxygen species (ROS), unless counterbalanced by antioxidants, can cause cellular damage under oxidative stress conditions; therefore, antioxidative defenses against ROS must be measured. With the development of nanotechnology, nanoparticles have found numerous applications in science, health, and industries. Magnetite nanoparticles (Fe 3 O 4 :MNPs) have attracted attention because of their peroxidase-like activity. In this study, hydroxyl radicals (•OH) generated by MNPs-catalyzed degradation of H 2 O 2 converted the N,N-dimethyl-p-phenylenediamine (DMPD) probe into its colored DMPD•+ radical cation, which gave an absorbance maximum at λ = 553 nm. In the presence of antioxidants, •OH was partly scavenged by antioxidants and produced less DMPD• + , causing a decrease in the 553 nm-absorbance. Antioxidant concentrations were calculated with the aid of absorbance differences between the reference and sample solutions. The linear working ranges and trolox equivalent antioxidant capacity coefficients of different classes of antioxidants were determined by applying the developed method. In addition, binary and ternary mixtures of antioxidants were tested to observe the additivity of absorbances of mixture constituents. The method was applied to real samples such as orange juice and green tea. Student t-test, F tests, and the Spearman’s rank correlation coefficient were used for statistical comparisons. 相似文献