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91.
R. Malathi G. Anitha K. Anand Solomon G. Suresh S. S. Rajan S. Narasimhan J. Josepha Lourdu Raj Geetha Gopalakrishnan 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(2):o70-o72
Nimbolide [systematic name: (4α,5α,6α,7α,15β,17α)‐7,15:21,23‐diepoxy‐6‐hydroxy‐4,8‐dimethyl‐1‐oxo‐18,24‐dinor‐11,12‐secochola‐2,13,20,22‐tetraene‐4,11‐dicarboxylic acid γ‐lactone methyl ester], C27H30O7, was isolated from the leaves of Azadirachta indica, and its isomer, isonimbolide [systematic name: (4α,5α,6α,7α,15α)‐7,15:21,23‐diepoxy‐6‐hydroxy‐4,8‐dimethyl‐1‐oxo‐18,24‐dinor‐11,12‐secochola‐2,16,20,22‐tetraene‐4,11‐dicarboxylic acid γ‐lactone methyl ester], was prepared from a novel rearrangement reaction of nimbolide, using boron trifluoride etherate and tetrabutylammonium bromide. The reaction conditions are probably responsible for the ether cleavage, double‐bond rearrangement and reformation of the ether linkage. As a result, there are conformational changes in two cyclopentane rings and the side‐chain –CH2COOMe group. In isonimbolide, an (24) hydrogen‐bond motif is observed. 相似文献
92.
Rashmi Paliwal Anand Prabha Rawat Monica Rawat J. P. N. Rai 《Applied biochemistry and biotechnology》2012,167(7):1865-1889
Bioligninolysis involves living organisms and/or their products in degradation of lignin, which is highly resistant, plant-originated polymer having three-dimensional network of dimethoxylated (syringyl), monomethoxylated (guaiacyl), and non-methoxylated (p-hydroxyphenyl) phenylpropanoid and acetylated units. As a major repository of aromatic chemical structures on earth, lignin bears paramount significance for its removal owing to potential application of bioligninolytic systems in industrial production. Early reports illustrating the discovery and cloning of ligninolytic biocatalysts in fungi was truly a landmark in the field of enzymatic delignification. However, the enzymology for bacterial delignification is hitherto poorly understood. Moreover, the lignin-degrading bacterial genes are still unknown and need further exploration. This review deals with the current knowledge about ligninolytic enzyme families produced by fungi and bacteria, their mechanisms of action, and genetic regulation and reservations, which render them attractive candidates in biotechnological applications. 相似文献
93.
G.V. Anand 《International Journal of Non》1976,11(4):277-284
A procedure for solving the problem of non-linear propagation of elastic surface waves is given. An expression for the particle displacement of the second harmonic is obtained. It is shown that the amplitude of the harmonic increases linearly with distance and time and is proportional to the square of the amplitude of the fundamental frequency wave. 相似文献
94.
95.
Microdroplets of 15-μm diameter are subjected to ultra-short laser pulses of intensities up to 1015Wcm−2 to produce hot dense plasma. The hot electrons produced in the microdroplet plasma result in efficient generation of hard X-rays in the range 50–150keV at an irradiance as low as 8×1014Wcm−2. The X-ray source efficiency is estimated to be about 2 ×10−7%. A prepulse that is about 11ns ahead of the main pulse strongly influences the droplet plasma and the resulting X-ray emission. For a similar laser prepulse and intensity, no measurable hard X-ray emission is observed when the laser is focused on a solid target of similar composition and this indicates that liquid droplet targets are best suited for hard X-ray generation in laser–plasma interactions. 相似文献
96.
Venkataramanarao G. Anand Simi K. Pushpan Sundararaman Venkatraman Tavarekere K. Chandrashekar 《Journal of Chemical Sciences》2003,115(5-6):711-720
Expanded porphyrins containing seven pyrrole/heterocyclic rings linked in a cyclic fashion are termed heptaphyrins. The number
ofπ-electrons in heptaphyrins depends on the number ofmeso carbon bridges used to link the heterocyclic rings, accordingly heptaphyrins with 28π-electrons and 30π-electrons are reported to date. Both condensation reactions of the appropriate precursors and acid-catalysed oxidative coupling
reactions have been utilized to synthesise the heptaphyrins. The 30π heptaphyrins exhibit rich structural diversity where some of the heterocyclic rings in the macrocycle undergo a 180° ring
flipping. An overview of the synthetic methods employed for the synthesis of heptaphyrins, their spectroscopic properties,
structural behaviour and aromatic properties are highlighted in this paper.
Dedicated to Professor C N R Rao on his 70th birthday 相似文献
97.
Hang Wang Anand S. Badami Abhishek Roy James E. McGrath 《Journal of polymer science. Part A, Polymer chemistry》2007,45(2):284-294
Nanophase‐separated, hydrophilic–hydrophobic multiblock copolymers are promising proton‐exchange‐membrane materials because of their ability to form various morphological structures that enhance transport. A series of poly(2,5‐benzophenone)‐activated, telechelic aryl fluoride oligomers with different block molecular weights were successfully synthesized by the Ni(0)‐catalyzed coupling of 2,5‐dichlorobenzophenone and the end‐capping agent 4‐chloro‐4′‐fluorobenzophenone. These telechelic oligomers (hydrophobic) were then copolymerized with phenoxide‐terminated, disulfonated poly(arylene ether sulfone)s (hydrophilic) by nucleophilic, aromatic substitution to form hydrophilic–hydrophobic multiblock copolymers. High‐molecular‐weight multiblock copolymers with number‐average block lengths ranging from 3000 to 10,000 g/mol were successfully synthesized. Two separate glass‐transition temperatures were observed via differential scanning calorimetry in the transparent multiblock copolymer films when each block length was longer than 6000 g/mol. Tapping‐mode atomic force microscopy also showed clear nanophase separation between the hydrophilic and hydrophobic domains and the influence of the block length as it increased from 6000 to 10,000 g/mol. Transparent and creasable films were solvent‐cast and exhibited moderate proton conductivity and low water uptake. These copolymers are promising candidates for high‐temperature proton‐exchange membranes in fuel cells, which will be reported separately in part II of this series. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 284–294, 2007 相似文献
98.
99.
Extraordinary Changes in the Electronic Structure and Properties of CdS and ZnS by Anionic Substitution: Cosubstitution of P and Cl in Place of S 下载免费PDF全文
Summayya Kouser S. R. Lingampalli Dr. P. Chithaiah Anand Roy Sujoy Saha Prof. Umesh V. Waghmare Prof. C. N. R. Rao 《Angewandte Chemie (International ed. in English)》2015,54(28):8149-8153
Unlike cation substitution, anion substitution in inorganic materials such as metal oxides and sulfides would be expected to bring about major changes in the electronic structure and properties. In order to explore this important aspect, we have carried out first‐principles DFT calculations to determine the effects of substitution of P and Cl on the properties of CdS and ZnS in hexagonal and cubic structures and show that a sub‐band of the trivalent phosphorus with strong bonding with the cation appears in the gap just above the valence band, causing a reduction in the gap and enhancement of dielectric properties. Experimentally, it has been possible to substitute P and Cl in hexagonal CdS and ZnS. The doping reduces the band gap significantly as predicted by theory. A similar decrease in the band gap is observed in N and F co‐substituted in cubic ZnS. Such anionic substitution helps to improve hydrogen evolution from CdS semiconductor structures and may give rise to other applications as well. 相似文献
100.
Rajesh Kumar Verma Sanjeet K. Verma Umesh Pankaj Anand K. Gupta Khushboo Khan Karuna Shankar 《Natural product research》2015,29(3):297-300
Andrographis paniculata Nees is an annual erect herb with wide medicinal and pharmacological applications due to the presence of andrographolide and other active chemical constituents. The large-scale cultivation of the kalmegh is not in practice. The aim of this study was to establish sustainable production systems of A. paniculata cv CIM-Megha with the application of different bioinoculants and chemical fertilisers. A. paniculata herb and andrographolide yield in the dried leaves was found to be highest (218% and 61.3%, respectively) in treatment T3 (NPK+Bacillus sp.) compared with T1 (control). The soil organic carbon, soil microbial respiration, soil enzymes activity and available nutrients improved significantly with combined application of bioinoculants and chemical fertilisers. 相似文献