全文获取类型
收费全文 | 167篇 |
免费 | 6篇 |
国内免费 | 2篇 |
专业分类
化学 | 131篇 |
晶体学 | 1篇 |
力学 | 2篇 |
数学 | 9篇 |
物理学 | 32篇 |
出版年
2023年 | 6篇 |
2022年 | 9篇 |
2021年 | 4篇 |
2020年 | 10篇 |
2019年 | 8篇 |
2018年 | 4篇 |
2017年 | 13篇 |
2016年 | 12篇 |
2015年 | 8篇 |
2014年 | 7篇 |
2013年 | 22篇 |
2012年 | 9篇 |
2011年 | 10篇 |
2010年 | 7篇 |
2009年 | 8篇 |
2008年 | 12篇 |
2007年 | 6篇 |
2006年 | 3篇 |
2005年 | 5篇 |
2004年 | 3篇 |
2003年 | 1篇 |
2002年 | 1篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1988年 | 1篇 |
排序方式: 共有175条查询结果,搜索用时 15 毫秒
91.
In this article, effect of addition of disc-shaped liquid crystalline material, namely 2, 3, 6, 7, 10, 11-hexabutyloxytriphenylene, in poly (3-hexylthiophene): [6, 6]-phenyl-C61-butyric acid methyl ester containing bulk heterojunction (BHJ) solar cells has been investigated. These disc-shaped molecules organise into ordered columnar hexagonal structures through intermolecular π ? π interactions as monitored by polarised light optical microscopy. Current–voltage characteristics of the device prepared with liquid crystal layer exhibited a short-circuit current of 10.5 mA cm?2 and a fill factor of 35%. The resultant power conversion efficiency (PCE) was 1.54%. The influence of varying the thickness of liquid crystal layer and annealing on these solar cells was also studied. The short circuit current and PCE of 12.9 mA cm?2 and 2.3% was achieved for these BHJ solar cells containing self-organised discotic liquid crystals in the active layer under one sun condition after annealing. 相似文献
92.
Varsha S. Honmore Supada R. Rojatkar Laxman U. Nawale Manisha A. Arkile Vijay M. Khedkar 《Natural product research》2016,30(24):2825-2830
Phytochemical investigation of methanol extract of the rhizomes of Alpinia officinarum Hance afforded four known diarylheptanoids 1,7-diphenylhept-4-en-3-one (1), 5-hydroxy-1,7-diphenyl-3-heptanone (2), 5-hydroxy-7-(4″-hydroxy-3″-methoxyphenyl)-1-phenyl-3-heptanone (3), and 7-(4″-hydroxy-3″-methoxyphenyl)-1-phenyl heptan-3-one (4).The acetate derivative of (4), 7-(4″-actetate-3″-methoxy phenyl)-1-phenyl heptan-3-one (5), was prepared. These diarylheptanoids exhibited promising in vitro and ex vivo antitubercular activity for the first time against dormant Mycobacterium tuberculosis H37Ra with the IC50 values between 0.34–47.69 and 0.13–22.91 μM, respectively. All compounds showed comparable activity against Mycobacterium bovis BCG (dormant phage) and did not show any activity against two gram + ve and two gram –ve bacterial strains. These compounds were also weakly cytotoxic up to 300 μM against three human cancer cell lines THP-1, Panc-1 and A549. 相似文献
93.
In the present work, degradation of 2,4-dinitrophenol (DNP), a persistent organic contaminant with high toxicity and very low biodegradability has been investigated using combination of hydrodynamic cavitation (HC) and chemical/advanced oxidation. The cavitating conditions have been generated using orifice plate as a cavitating device. Initially, the optimization of basic operating parameters have been done by performing experiments over varying inlet pressure (over the range of 3–6 bar), temperature (30 °C, 35 °C and 40 °C) and solution pH (over the range of 3–11). Subsequently, combined treatment strategies have been investigated for process intensification of the degradation process. The effect of HC combined with chemical oxidation processes such as hydrogen peroxide (HC/H2O2), ferrous activated persulfate (HC/Na2S2O8/FeSO4) and HC coupled with advanced oxidation processes such as conventional Fenton (HC/FeSO4/H2O2), advanced Fenton (HC/Fe/H2O2) and Fenton-like process (HC/CuO/H2O2) on the extent of degradation of DNP have also been investigated at optimized conditions of pH 4, temperature of 35 °C and inlet pressure of 4 bar. Kinetic study revealed that degradation of DNP fitted first order kinetics for all the approaches under investigation. Complete degradation with maximum rate of DNP degradation has been observed for the combined HC/Fenton process. The energy consumption analysis for hydrodynamic cavitation based process has been done on the basis of cavitational yield. Degradation intermediates have also been identified and quantified in the current work. The synergistic index calculated for all the combined processes indicates HC/Fenton process is more feasible than the combination of HC with other Fenton like processes. 相似文献
94.
Seiichiro Higashiya Thamarai Selvi Devarajan Manisha V. Rane‐Fondacaro Christopher Dangler Jeremy Snyder Pradeep Haldar 《Helvetica chimica acta》2009,92(8):1600-1609
Synthesis of ionic liquids (IL) based on oxygen‐containing spirobipyrrolidinium salts with BF4, BF3C2F5, and NTf2 as counterions was undertaken. Their physical and electrochemical properties were evaluated for suitability for Room Temperature Ionic Liquids (RTIL) application. Reduction in melting point occurred upon exchange of C(2) by an O‐atom of spirobipyrrolidinium, without sacrificing the electrochemical stability; while introduction of alkyl groups between the N‐ and O‐atoms led to incorporation of asymmetry, and hence reduced the melting points, and viscosity. 相似文献
95.
Joshi R Poonam Saini R Guleria S Babu GD Kumari M Gulati A 《Natural product communications》2011,6(8):1155-1158
Volatile flavour components of tea flowers (Camellia sinensis) were isolated by two methods viz. simultaneous distillation extraction (SDE), supercritical fluid extraction (SFE), analyzed by GC and GC/MS and compared with headspace analysis (HS). The composition of the volatile components extracted by the three methods differed considerably. In SFE, phenylethanol (14.7%), linalool (7.9%), (E)-linalool oxide furanoid (3.5%), epoxy linalool (1.6%), geraniol (2.3%) and hotrienol (1.5%) were major components. m-Xylene (2.6%), (E)-linalool oxide pyranoid (5.4%), p-myrcene (5.2%), alpha-cadinol (4.3%) and methyl palmitate (2.9%) were major compounds isolated by SDE. 3-hexenol (2.1%) (E)-4,8-dimethyl-1,3,7-nonatriene (20.9%) and linalool (35.1%) are major components in headspace analysis. Acetophenone and pheromone germacrene D is detected in tea flowers by all the methods studied. Floral, fresh and fruity odour of tea flowers is retained by SFE as there is very little loss of heat sensitive volatiles in SFE. The flavour isolated from SFE has superior quality compared to SDE. 相似文献
96.
Basi V. Subba Reddy Sankham Madhusudana Reddy Swain Manisha Chinnala Madan 《Tetrahedron: Asymmetry》2011,22(5):846-535
A catalytic asymmetric Henry reaction has been developed using a novel chiral Cu(II) complex derived from (R)-2-(diphenylmethanol)-l-(2-pyridylmethyl)pyrrolidine and copper(II) acetate in ethanol under mild conditions. The corresponding chiral 2-nitro-1-arylethanol derivatives were obtained in high yields with moderate to good enantiomeric excess (up to 86% ee). The results indicate that the coordination of a metal atom to the nitrogen of the pyridine ring is essential in determining the stereochemistry of the process. 相似文献
97.
Ankit Aggarwal Anand Louis Manisha Bansal Naveen Garg Neelima Gupta Shubham Gupta Surabhi Jain 《Mathematical Programming》2013,141(1-2):527-547
We consider the facility location problem where each facility can serve at most U clients. We analyze a local search algorithm for this problem which uses only the operations of add, delete and swap and prove that any locally optimum solution is no more than 3 times the global optimum. This improves on a result of Chudak and Williamson who proved an approximation ratio of ${3+2\sqrt{2}}$ for the same algorithm. We also provide an example which shows that any local search algorithm which uses only these three operations cannot achieve an approximation guarantee better than 3. 相似文献
98.
AbstractMilitary radar has the requirement of 24 × 7 operation in harsh environments with a high level of safety and integrity built in for equipment and personnel working with it. This article presents an application of a microwave photonic network for phased-array military radar. The design challenge is to realize faithful reproduction of the input microwave signals over extreme temperature and frequency ranges. Environmental testing has been carried out to validate the performance of the proposed microwave photonic network over 2–4 GHz and a temperature range of –20°C to +55°C. The result shows that the photonic network can be successfully utilized for phased-array radar. 相似文献
99.
Manisha V. Bagal Bhagyashree J. Lele Parag R. Gogate 《Ultrasonics sonochemistry》2013,20(5):1217-1225
Sonochemical removal of 2,4-dinitrophenol (DNP) has been investigated using ultrasonic bath, with an operating capacity of 7 L, fitted with a large transducer with longitudinal vibrations having a 1 kW rated power output and operating frequency of 25 kHz. It has been revealed from calorimetric studies that maximum power is dissipated at a capacity of 7 L. The concentration of DNP has been monitored with an objective of evaluation of the efficacy of ultrasonic reactor in combination with process intensifying approaches for the removal of DNP. The effect of operating pH and additives such as hydrogen peroxide and ferrous iron activated persulfate on the extent of removal of DNP has been investigated. It has been observed that the extent of removal is greater at lower pH (pH 2.5 and 4) than at higher pH (pH 10). The combined treatment strategies such as ultrasound (US)/Fenton, US/advanced Fenton and US/CuO/H2O2 have also been investigated with an objective of obtaining complete removal of DNP using hybrid treatment strategies. The extent of removal has been found to increase significantly in US/Fenton process (98.7%) as compared to that using US alone (5.8%) which demonstrates the efficacy of the combined process. First order kinetics has been fitted for all the approaches investigated in the work. Calculations of cavitational yield indicated the superiority of the reactor design as compared to the conventional ultrasonic horn type reactors. The main intermediates formed during the process of removal of DNP have been identified. 相似文献
100.
Prakash Chandra Sati Manisha AroraSunil Chauhan Manoj KumarSandeep Chhoker 《Journal of Physics and Chemistry of Solids》2014
Bi1−xDyxFeO3 (x=0.0, 0.03, 0.05, 0.07, 0.10 and 0.12) ceramics were synthesized by solid state reaction method. Effects of Dy substitution on structural distortion, magnetic and optical properties of BiFeO3 were examined by X-ray diffraction, Raman and UV–Visible spectroscopy. The samples were found to crystallize in rhombohedral structure of BiFeO3 with R3c space group. The reduction in lattice parameters and unit cell volume indicate the distortion in FeO6 octahedra of the rhombohedral structure without any signature of phase transformation up to x=0.12. The predictable weak ferromagnetic hysteresis loops can be observed in the Dy doped samples with maximum remnant magnetization of 0.2103 emu/g for x=0.12. The weak ferromagnetism is ascribed to the suppressed spiral spin structure and magnetically active characteristic of Dy3+ ions together with ferromagnetic coupling between Dy3+ and Fe3+ ions. With optical band gap in visible region, Dy doped BiFeO3 ceramics are potential material for optoelectronic device and solar cell applications. 相似文献