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471.
Measurement of soil radioactivity levels and radiation hazard assessment in mid Rechna interfluvial region,Pakistan 总被引:1,自引:0,他引:1
Abdul Jabbar Waheed Arshed Arshad Saleem Bhatti Syed Salman Ahmad Saeed-Ur-Rehman Muhammad Dilband 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(2):371-378
Radioactivity levels in soil samples, collected from mid Rechna interfluvial region, Pakistan have been estimated by using
gamma ray spectrometric technique. 226Ra, 232Th, the primordial radionuclide 40K and the artificial radionuclide 137Cs have been measured in the soil of the study area. The mean radioactivity levels of 226Ra, 232Th, 40K and 137Cs were found to be 49.0 ± 1.6, 62.4 ± 3.2, 670.6 ± 33.9 and 3.5 ± 0.4 Bq kg−1 respectively. The mean radium equivalent activity (Raeq), outdoor radiation hazard index (H
out), indoor radiation hazard index (H
in) and terrestrial absorbed dose rate for the area under study were determined as 189.9 ± 8.8 Bq kg−1, 0.51, 0.65 and 70.1 nGy h−1 respectively. The annual effective dose to the public was estimated to be 0.43 mSv. The measured values are comparable with
other global radioactivity measurements and are found to be safe for public and environment. 相似文献
472.
We establish some fixed point theorems for fuzzy contractive and fuzzy locally contractive mappings on a compact metric space with the d∞-metric for fuzzy sets. Our results generalized well-known classical results of Edelstein. 相似文献
473.
In this paper we develop a non-polynomial quintic spline function to approximate the solution of third order linear and non-linear
boundary value problems associated with odd-order obstacle problems. Such problems arise in physical oceanography and can
be studied in the framework of variational inequality theory. The class of methods are second and fourth order convergent.
End equations of the splines are derived and truncation error is obtained. Two numerical examples are given to illustrate
the applicability and efficiency of proposed method. It is shown that the new method gives approximations, which are better
than those produced by other methods. 相似文献
474.
Safia Anjum M. Shahid RafiqueM. Khaleeq-ur-Rahman K. SirajArslan Usman S.I. Hussain S. Naseem 《Journal of magnetism and magnetic materials》2012,324(5):711-716
In this paper we present the effect of low substrate temperature on structural, morphological, magnetic and optical properties of Ba-hexaferrite thin films. Films were deposited on single crystal Silicon (1 0 0) substrate employing the Pulsed Laser Deposition (PLD) technique. The structural, morphological, magnetic and optical properties are found to be strongly dependent on substrate temperature. The low substrate temperatures (room temperature to 200 °C) restrict the formation of larger grains. For the higher substrate temperature i.e., 400 °C, the grain size of the deposited thin film are much larger. The film grown at low substrate temperature do not show any anisotropy. As the substrate temperature is increased, the easy axis of the films alinged itself in the direction parallel to the film plane whereas the hard axis remained in the perpendicular direction. The higher substrate temperature caused the uniaxial magnetic anisotropy, which is very important in magnetic recording devices. The saturation magnetization and optical band gap energy values of 62 emu/cc and 1.75 eV, respectively, were achieved for the film of thickness 500 nm deposited at 400 °C. Higher values of coercivity, squareness and films thickness are associated with the growth of larger grains at higher substrate temperature. 相似文献
475.
Tariq Mahmood Chuanbao Cao Faheem K. Butt Haibo Jin Zahid Usman Waheed S. Khan Zulfiqar Ali Muhammad Tahir Faryal Idrees Maqsood Ahmed 《Physica B: Condensed Matter》2012,407(22):4495-4501
The ultrasoft pseudopotential technique is used to explore the elastic, electronic and optical properties of cotunnite TiO2 using LDA and GGA proposed by Perdew Wang (PW91), Perdew–Burke–Ernzerhof (PBE) functional as defined by Wu and Cohen (PBEWC) and PBE functional for solids (PBESOL). The calculated elastic constants bulk modulus, shear modulus and Young’s modulus are in agreement with the previous theoretical reports. From our investigated shear anisotropy factors (A1, A2, and A3), we infer that cotunnite TiO2 is strong anisotropy in case of A1 and A2 and less anisotropy in case of A3. The value of mean sound speed and Debye temperature are calculated using the obtained values of elastic moduli. The calculated structural parameters are in accord with the reported experiment and theoretical results. Our obtained values of direct bandgaps show an improvement over the other previous theoretical reports. The values of the dielectric constant (ε1(ω)) of cotunnite TiO2 calculated within LDA and GGA approximations are 7.655 (LDA (CA-PZ)), 7.578 (GGA (PW91)), 7.685 (GGA (WC)) and 7.655 (GGA (PBESOL)), which are slightly higher than the experimental values of rutile (6.69) and anatase (6.55) polymorphs. The obtained values of the refractive index are consistent with rutile TiO2 and higher than anatase phase. The investigated imaginary part of dielectric constant and absorption spectrum reflect that the cotunnite TiO2 is a weak photocatalytic material as compared to anatase and similar to rutile phases. 相似文献
476.
Iris recognition technology recognizes a human based on his/her iris pattern.However,the accuracy of the iris recognition technology depends on accurate iris localization.Localizing a pupil region in the presence of other low-intensity regions,such as hairs,eyebrows,and eyelashes,is a challenging task.This study proposes an iris localization technique that includes a localizing pupillary boundary in a sub-image by using an integral projection function and two-dimensional shape properties(e.g.,area,geometry,and circularity).The limbic boundary is localized using gradients and an error distance transform,and the boundary is regularized with active contours.Experimental results obtained from public databases show the superiority of the proposed technique over contemporary methods. 相似文献
477.
Arshad Khan 《PAMM》2007,7(1):2020133-2020134
In this paper a fourth-order variable coefficient parabolic partial differential equation, that governs the behaviour of a vibrating beam, is solved by using a three level method based on non-polynomial quintic spline in space and finite difference discretization in time. We also obtain two new high accuracy schemes of O (k4, h6) and O (k4, h8) and two new schemes which are analogues of Jain's formula for the non-homogeneous case. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
478.
Dr. Arshad Hussain Hajera Gul Waseem Raza Dr. Salman Qadir Dr. Muhammad Rehan Dr. Nadeem Raza Aasif Helal Dr. M. Nasiruzzaman Shaikh Dr. Md. Abdul Aziz 《Chemical record (New York, N.Y.)》2024,24(4):e202300352
Recently, carbon neutrality has been promoted as a potentially practical solution to global CO2 emissions and increasing energy-consumption challenges. Many attempts have been made to remove CO2 from the environment to address climate change and rising sea levels owing to anthropogenic CO2 emissions. Herein, membrane technology is proposed as a suitable solution for carbon neutrality. This review aims to comprehensively evaluate the currently available scientific research on membranes for carbon capture, focusing on innovative microporous material membranes used for CO2 separation and considering their material, chemical, and physical characteristics and permeability factors. Membranes from such materials comprise metal-organic frameworks, zeolites, silica, porous organic frameworks, and microporous polymers. The critical obstacles related to membrane design, growth, and CO2 capture and usage processes are summarized to establish novel membranes and strategies and accelerate their scaleup. 相似文献
479.
Dr. Muhammad Faheem Dr. Arshad Hussain Dr. Muhammad Ali Dr. Md. Abdul Aziz 《Chemical record (New York, N.Y.)》2024,24(1):e202300268
Aluminum-sulfur batteries (AlSBs) exhibit significant potential as energy storage systems due to their notable attributes, including a high energy density, cost-effectiveness, and abundant availability of aluminum and sulfur. In order to commercialize AlSBs, an understanding of their working principles is necessary. In this review, we examine the current advancements in cathodes, both in theory and practice, as well as the progress made in aqueous and nonaqueous electrolytes. We also explore the modifications made to separators and the theoretical understanding of problems associated with AlSBs. Furthermore, we discuss future research directions aimed at resolving these issues. Our aim is to summarize the current progress in AlSBs and, based on recent progress and understanding of the mechanism, help design a battery to overcome the challenges that such batteries have been facing. 相似文献
480.
Sheng‐Li Li Anwar Usman Ibrahim A. Razak Hoong‐Kun Fun Jie‐Ying Wu Yu‐Peng Tian Min‐Hua Jiang Zu‐Yao Chen 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(5):m181-m183
In the title compound, [Ni(CH5N3S)2(H2O)2](C4H3O4)2·2H2O, the Ni atom lies on a center of symmetry and is coordinated by N and S atoms from two thiosemicarbazide ligands and the O atoms of two water molecules in a distorted octahedral geometry. In the asymmetric unit, the three components are linked together by one O—H⋯O and two N—H⋯O hydrogen bonds. The packing is built from molecular ribbons parallel to the b direction, stabilized by intramolecular hydrogen bonds, and by one N—H⋯S and two N—H⋯O intermolecular hydrogen bonds. The ribbons are further connected into columns by N—H⋯O interactions and then into a three‐dimensional network by three O—H⋯O hydrogen bonds. 相似文献