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91.
Katsuhito Suzuki Hiroaki Okumura Kazuo Kitagawa Shinji Sato Antonio Norio Nakagaito Hiroyuki Yano 《Cellulose (London, England)》2013,20(1):201-210
Microfibrillated cellulose (MFC), a mechanically fibrillated pulp mostly consisting of nanofibrils, is a very attractive material because of its high elastic modulus and strength. Although much research has been done on composites of MFC and polypropylene (PP), it has been difficult to produce such composites at an industrial level because of the difficulties in using MFC in such composites are not only connected to the polarity (that can be improved with compatibilizers), but also with the challenge to make a homogeneous blend of the components, and also the low temperature stability of cellulose that could cause problems during processing. We developed a new processing method which enables continuous microfibrillation of pulp and its melt compounding with PP. Never-dried kraft pulp and powdered PP were used as raw materials to obtain MFC by kneading via a twin-screw extruder. Scanning electron microscopy showed nano to submicron wide fibers entangled in the powdered PP. MFC did not aggregate during the melt compounding process, during which the water content was evaporated. Maleic anhydride polypropylene (MAPP) was used as a compatibilizer to reinforce interfacial adhesion between the polar hydroxyl groups of MFC and non-polar PP. We investigated the effect of MAPP content on the mechanical properties of the composite, which were drastically improved by MAPP addition. Needle-leaf unbleached kraft pulp (NUKP)-derived MFC composites had better mechanical properties than needle-leaf bleached kraft pulp (NBKP)-derived MFC composites. Injection molded NUKP-derived MFC composites had good mechanical and thermal properties. The tensile modulus of 50 wt% MFC composite was two times, and the tensile strength 1.5 times higher than that of neat PP. The heat distortion temperature of 50 wt% MFC content composite under 1.82 MPa flexural load was increased by 53 °C, from 69 to 122 °C. This newly developed continuous process using powder resin has the potential for application at an industrial level. 相似文献
92.
Dr. Masayuki Gon Junko Wakabayashi Masashi Nakamura Prof. Dr. Kazuo Tanaka Prof. Dr. Yoshiki Chujo 《化学:亚洲杂志》2021,16(6):696-703
We demonstrate that multi-fluorinated boron-fused azobenzene (BAz) complexes can work as a strong electron acceptor in electron donor-acceptor (D-A) type π-conjugated polymers. Position-dependent substitution effects were revealed, and the energy level of the lowest unoccupied molecular orbital (LUMO) was critically decreased by fluorination. As a result, the obtained polymers showed near-infrared (NIR) emission (λPL=758–847 nm) with high absolute photoluminescence quantum yield (ΦPL=7–23%) originating from low-lying LUMO energy levels of the BAz moieties (−3.94 to −4.25 eV). Owing to inherent solid-state emissive properties of the BAz units, deeper NIR emission (λPL=852980 nm) was detected in film state. Clear solvent effects prove that the NIR emission is from a charge transfer state originating from a strong D-A interaction. The effects of fluorination on the frontier orbitals are well understandable and predictable by theoretical calculation with density functional theory. This study demonstrates the effectiveness of fluorination to the BAz units for producing a strong electron-accepting unit through fine-tuning of energy gaps, which can be the promising strategy for designing NIR absorptive and emissive materials. 相似文献
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96.
Shigeyoshí Nishino Yasuhiro Nagato Yoshihiro Hasegawa Hisanao Yamamoto Kazuo Kamaike Yoshiharu Ishido 《Heteroatom Chemistry》1991,2(1):187-196
Reagent systems of sodium– and tetrabutylammonium nitrite–acetic anhydride were proved to be extremely efficient for the deanilidation of nucleoside 3′-phosphoranilidates, whose reactions were rapid with the former and instant with the latter. It was further found that the reagent system is applicable to oligonucleotide synthesis provided that the exocyclic amino groups of 2′-deoxyadenosine, 2′-deoxyguanosine, and 2′-deoxycytidine were protected by succinylation. 相似文献
97.
Osamu Takimura Hiroyuki Fuse Katsuzi Murakami Kazuo Kamimura Yukiho Yamaoka 《应用有机金属化学》1996,10(9):753-756
Uptake and reduction of arsenate [AS(V)] by Dunaliella sp. cells were determined to investigate the metabolic processes of arsenic in the alga. Cellular uptake of arsenic by Dunaliella sp. cells was markedly affected by the form of arsenic in the medium. The content of arsenic taken up by Dunaliella sp. cells increased rapidly with time on addition of As(V) to the medium. However, in the case of addition of arsenite [As(III)], the gradient of arsenic uptake by Dunaliella sp. cells was low, and arsenic content was small. In the water-soluble fraction of arsenic taken up by Dunaliella sp. cells with exposure to As(V), arsenic was in the forms of organic arsenic, As(V) and As(III). The content of As(V) in the water-soluble fraction increased with exposure time. The content of As(III) also increased with time, but remained constant after 5 h of exposure. On the other hand, organic arsenic content was small and did not increase with time. It was found that Dunaliella sp. takes up As(V) and readily reduces it to As(III) 相似文献
98.
99.
Prof. Dr. Masahiro Sadakane Sachie Moroi Yoshifumi Iimuro Dr. Natalya Izarova Prof. Dr. Ulrich Kortz Prof. Dr. Shinjiro Hayakawa Kazuo Kato Dr. Shuhei Ogo Dr. Yusuke Ide Prof. Dr. Wataru Ueda Prof. Dr. Tsuneji Sano 《化学:亚洲杂志》2012,7(6):1331-1339
Ruthenium(III)‐substituted α‐Keggin‐type silicotungstates with pyridine‐based ligands, [SiW11O39RuIII(Py)]5?, (Py: pyridine ( 1 ), 4‐pyridine‐carboxylic acid ( 2 ), 4,4′‐bipyridine ( 3 ), 4‐pyridine‐acetamide ( 4 ), and 4‐pyridine‐methanol ( 5 )) were prepared by reacting [SiW11O39RuIII(H2O)]5? with the pyridine derivatives in water at 80 °C and then isolated as their hydrated cesium salts. These compounds were characterized using cyclic voltammetry (CV), UV/Vis, IR, and 1H NMR spectroscopy, elemental analysis, titration, and X‐ray absorption near‐edge structure (XANES) analysis (Ru K‐edge and L3‐edge). Single‐crystal X‐ray analysis of compounds 2 , 3 , and 4 revealed that RuIII was incorporated in the α‐Keggin framework and was coordinated by pyridine derivatives through a Ru? N bond. In the solid state, compounds 2 and 3 formed a dimer through π? π interaction of the pyridine moieties, whereas they existed as monomers in solution. CV indicated that the incorporated RuIII–Py was reversibly oxidized into the RuIV–Py derivative and reduced into the RuII–Py derivative. 相似文献
100.
The kinetics of the flattening of surface corrugations of float glasses were investigated in dry nitrogen at 610 to 670°C. The amplitude of the sinusoidal surface profile decayed exponentially with time while its wavelength remained constant. The dependence of decay rate on wavelength indicated that the process is controlled by the viscous flow. From the obtained rate constant the viscosity was calculated using the surface energy value determined independently by the zero-creep method. The viscosity thus obtained reflects the mass transport property in the vicinity of the glass surface. It was several times larger than that determined by the fibre elongation or intrusion method which should reflect the bulk properties. No difference in the decay rate was observed on both the surfaces of float glass of which only one side had been exposed to molten tin during the glass manufacturing process. 相似文献