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排序方式: 共有669条查询结果,搜索用时 31 毫秒
661.
Abdel Haleem Mostafa Hussein 《Heteroatom Chemistry》1997,8(1):1-6
The reactions of formaldehyde and acetaldehyde with active methylene compounds, followed by reaction with cyanoacetic acid hydrazide 2, afforded N-aminopyridine-2-one derivatives 5a-f. In contrast, the reactions of cyanoacetic acid hydrazide 2 with aliphatic aldehydes and cyanothioacetamide afforded pyridinethione derivatives 11a-b. Also, the reactions of active methylene compounds with formaldehyde and cyanoacetamide afforded pyridin(1H)-2-one derivatives 12a-c. The reactions of 5b with aldehydes and ketones afforded compounds 13a, b, 14, and 15, respectively. The reactions of 5b with arylidinemalononitriles 16a,b afforded isoquinoline derivatives 19a,b. Compound 19b by hydrolysis gave the final product 20. Compound 20 could also be formed by hydrolysis of 5b to give 21, followed by the reaction with 16b. © 1997 John Wiley & Sons, Inc. 相似文献
662.
Polu Anji Reddy Kareem Aseel A. Rasheed Hussein Kh. 《Journal of Solid State Electrochemistry》2023,27(2):409-416
Journal of Solid State Electrochemistry - In the present study, we report the synthesis and characterisation of solid polymer electrolytes (SPEs) based on polymer poly(ethylene oxide) (PEO), salt... 相似文献
663.
Abdalghani Daaoub James M. F. Morris Vanessa A. Béland Paul Demay-Drouhard Amaar Hussein Simon J. Higgins Hatef Sadeghi Richard J. Nichols Andrea Vezzoli Thomas Baumgartner Sara Sangtarash 《Angewandte Chemie (International ed. in English)》2023,62(24):e202302150
Most studies in molecular electronics focus on altering the molecular wire backbone to tune the electrical properties of the whole junction. However, it is often overlooked that the chemical structure of the groups anchoring the molecule to the metallic electrodes influences the electronic structure of the whole system and, therefore, its conductance. We synthesised electron-accepting dithienophosphole oxide derivatives and fabricated their single-molecule junctions. We found that the anchor group has a dramatic effect on charge-transport efficiency: in our case, electron-deficient 4-pyridyl contacts suppress conductance, while electron-rich 4-thioanisole termini promote efficient transport. Our calculations show that this is due to minute changes in charge distribution, probed at the electrode interface. Our findings provide a framework for efficient molecular junction design, especially valuable for compounds with strong electron withdrawing/donating backbones. 相似文献
664.
Systematic investigations on thallium monoselenide single crystal photoconductivity were reported at 300 K as a function of excitation intensity, side illumination, and wavelength. The samples were prepared using Bridgman technique. The photoconductivity as a function of the modulation frequency of the incident light was plotted at different values of light intensity. The effect of light intensity on the photocarrier lifetime was studied. The relation between the photocurrent and applied voltage at different values of light intensity was represented graphically. Side illumination effect in all these relations was checked. The spectral distribution of the photoconductivity of TlSe in the spectral region 1.24 ev to 1.77 ev was measured, and the energy gap was evaluated. All results were discussed and analyzed. Studies for such samples are very important and necessary in order to understand their use as photoconductor. 相似文献
665.
Asif Hayat Muhammad Sohail Atef El Jery Khadijah M. Al-Zaydi Khaled F Alshammari Javid Khan Hamid Ali Zeeshan Ajmal T. A. Taha Israf Ud Din Rashid Altamimi Mahmoud Ali Hussein Yas Al-Hadeethi Yasin Orooji Mohd Zahid Ansari 《Chemical record (New York, N.Y.)》2023,23(5):e202200171
Graphitic carbon nitride (g-C3N4) has gained tremendous interest in the sector of power transformation and retention, because of its distinctive stacked composition, adjustable electronic structure, metal-free feature, superior thermodynamic durability, and simple availability. Furthermore, the restricted illumination and extensive recombination of photoexcitation electrons have inhibited the photocatalytic performance of pure g-C3N4. The dimensions of g-C3N4 may impact the field of electronics confinement; as a consequence, g-C3N4 with varying dimensions shows unique features, making it appropriate for a number of fascinating uses. Even if there are several evaluations emphasizing on the fabrication methods and deployments of g-C3N4, there is certainly an insufficiency of a full overview, that exhaustively depicts the synthesis and composition of diverse aspects of g-C3N4. Consequently, from the standpoint of numerical simulations and experimentation, several legitimate methodologies were employed to deliberately develop the photocatalyst and improve the optimal result, including elements loading, defects designing, morphological adjustment, and semiconductors interfacing. Herein, this evaluation initially discusses different dimensions, the physicochemical features, modifications and interfaces design development of g-C3N4. Emphasis is given to the practical design and development of g-C3N4 for the various power transformation and inventory applications, such as photocatalytic H2 evolution, photoreduction of CO2 source, electrocatalytic H2 evolution, O2 evolution, O2 reduction, alkali-metal battery cells, lithium-ion batteries, lithium–sulfur batteries, and metal-air batteries. Ultimately, the current challenges and potential of g-C3N4 for fuel transformation and retention activities are explored. 相似文献
666.
667.
Ahmed M. El‐Agrody Fathy A. Eid Hussein A. Emam Hany M. Mohamed Ahmed H. Bedair 《ChemInform》2002,33(38):123-123
668.
Current-voltage characteristics measured on TlGaTe2 single crystals reveal switching effects at temperatures below 263 K. The current-voltage characteristics are symmetric with respect to the polarity of the applied field. The threshold parameters for switching are found to depend on temperature, illumination intensity and sample thickness. 相似文献
669.
S. A. Hussein 《Crystal Research and Technology》1989,24(6):635-638
Conductivity type, carrier concentration and carrier mobility of InTe samples grown by Bridgmann technique were determined by the Hall effect and electrical conductivity measurements. The study was performed in the temperature range 150–480 K. Two samples with different growth rate were used in the investigation. The samples under test were P-type conducting, in accordance with previous measurements of undoped material. The Hall coefficient was found to be isotropic yielding room temperature hole concentration in the range 1015 – 1016 cm−3. The hole mobilities of InTe samples were in the range 1.17 × 103 – 2.06 × 103 cm2/V · sec at room temperature. The band – gap of InTe determined from Hall coefficient studies has been obtained equal to 0.34 ev. The scattering mechanism was checked, and the electrical properties were found to be sensitive to the crystal growth rate. 相似文献