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961.
Ken‐ichi Nakashima Naohito Abe Fumiko Kamiya Tetsuro Ito Masayoshi Oyama Munekazu Iinuma 《Helvetica chimica acta》2009,92(10):1999-2008
The three novel methylene bis[flavonoids] 1 – 3 , the novel 2‐flavene 4 , the new naturally occurring flavan 5 , and the new retro‐dihydrochalcone 6 were isolated from dragon's blood of Daemonorops draco, together with seven known compounds. The structures were elucidated by extensive 1D‐ and 2D‐NMR spectroscopic analysis. 相似文献
962.
Non-stoichiometric FexWN2 (x∼0.72) was synthesized via leaching of Fe from layer-structured stoichiometric FeWN2 by soaking in sulfuric acid at ca. 50 °C. The synthesized products were characterized by powder X-ray diffraction (pXRD), secondary electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and magnetic measurements. Non-stoichiometric FexWN2 has the same symmetry unit cell as stoichiometric FeWN2 (P63/mmc), but the lattice parameters change: the a-axis expands by 0.16% while the c-axis decreases by 1.5%. Polycrystalline powder of FexWN2 showed similar morphologies as those of FeWN2. The calculated electronic structure of stoichiometric FeWN2 shows a more ionic-bonding character between Fe and N than that between W and N, which presumably allows for the partial Fe leaching from between the W-N prismatic layers. The magnetic susceptibility of FexWN2 smoothly decreases with increasing temperature from 3 to 300 K, unlike the broad maximum seen near 27 K in stoichiometric FeWN2. 相似文献
963.
Tadao Kondo Toshiyuki Tomoo Hiroyuki Abe Minoru Isobe Toshio Goto 《Journal of carbohydrate chemistry》2013,32(7):857-878
ABSTRACT Glycosylation of an 8-unprotected sialyl fluoride 16 with 2β-chloro-3β-phenylthio-Neu5Ac 2 gave the desired α-disialate 23. Subsequent glycosylation of a thiolactoside 19 with the disialyl fluoride 23 gave the tetrasaccharide 28. Synthesis of GD3 1 was realized by condensation of the tetrasaccharide 28 with azidosphingosine 31, following our previously reported GM3 synthesis procedure. 相似文献
964.
Eiichi Abe 《代数通讯》2013,41(12):1271-1307
965.
Two new meroterpenoids, biyoulactones D (1) and E (2), were isolated from the roots of Hypericum chinense, and their structures were elucidated on the basis of spectroscopic data and conformational analysis. Biyoulactones D (1) and E (2) are structurally unique tricyclic meroterpenoids having an octahydroindene ring, a γ-butyrolactone ring, and a β-diketone moiety. 相似文献
966.
Rekha?Goswami?ShresthaEmail author Suraj?Chandra?Sharma Kenichi?Sakai Hideki?Sakai Masahiko?Abe 《Colloid and polymer science》2012,290(4):339-348
Formation of wormlike micelles (WLMs) in an aqueous mixture of polyoxyethylene cholesteryl ether (ChEOn; where n = 20 and 30) and polyoxyethylene dodecyl ether (C12EOm; where m = 3 and 4) has been reported; rheological and small angle X-ray scattering (SAXS) measurements have been performed in the
micellar solutions of ChEOn as a function of C12EOm for the structural elucidation. When lipophilic cosurfactant, C12EOm is added to the micellar solutions of ChEOn, it favors the sphere-to-cylinder transition due to the penetration of C12EOm in the palisade layer of ChEOn micelle accompanying an increase in viscosity. When the concentration of C12EOm is increased, entangled network of WLMs is formed. A strong shear thinning has been observed in highly viscous samples indicating
the presence of transient networks. Such samples exhibited viscoelastic behavior and could be described by the Maxwell model
with a single stress relaxation mode. A maximum is observed in zero-shear viscosity-C12EOm plot. With further addition of C12EOm, viscosity declines and ultimately a phase separation occurs with the formation of turbid solution of vesicular dispersion.
This decline has been interpreted in terms of micellar branching induced by an increase in endcap energy, E
c (which is compensated by the formation of branch points, having a mean curvature opposite to that of endcaps). The C12EOm induced one-dimensional micellar growth has been confirmed by SAXS. 相似文献
967.
Yuichiro Abe Dr. Satoru Karasawa Dr. Noboru Koga 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(47):15038-15048
2,4‐Trifluoromethylquinoline (TFMAQ) derivatives that have amine ( 1 ), methylamine ( 2 ), phenylamine ( 3 ), and dimethylamine ( 4 ) substituents at the 7‐position of the quinoline ring were prepared and crystallized. Six crystals including the crystal polymorphs of 2 (crystal GB and YG) and 3 (crystal B and G) were obtained and characterized by X‐ray crystallography. In solution, TFMAQ derivatives emitted relatively strong fluorescence (${\lambda {{{\rm f}\hfill \atop {\rm max}\hfill}}}$ =418–469 nm and Φf(s)=0.23–0.60) depending on the solvent polarity. From Lippert–Mataga plots, Δμ values in the range of 7.8–14 D were obtained. In the crystalline state, TFMAQ derivatives emitted at longer wavelengths (${\lambda {{{\rm f}\hfill \atop {\rm max}\hfill}}}$ =464–530 nm) with lower intensity (Φf(c)=0.01–0.28) than those in n‐hexane solution. The polymorphous crystals of 2 and 3 emitted different colors: 2 , ${\lambda {{{\rm f}\hfill \atop {\rm max}\hfill}}}$ =470 and 530 nm with Φf(c)=0.04 and approximately 0.01 for crystal GB and YG, respectively; and 3 , ${\lambda {{{\rm f}\hfill \atop {\rm max}\hfill}}}$ =464 and 506 nm with Φf(c)=0.28 and approximately 0.28 for crystal B and G, respectively. In both crystal polymorphs of 2 and 3 , crystals GB and G showed emission color changes by heating/melting/cooling cycles that were representative. By following the color changes in heating at the temperature below the melting point with X‐ray diffraction measurements and X‐ray crystallography, the single‐crystal‐to‐single‐crystal transformations from crystal GB to YG for 2 and from crystal B to G for 3 were revealed. 相似文献
968.
Prof. Dr. Tsutomu Hoshino Akifumi Chiba Naomi Abe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(41):13108-13116
Lanosterol synthase catalyzes the polycyclization reaction of (3S)‐2,3‐oxidosqualene ( 1 ) into tetracyclic lanosterol 2 by folding 1 in a chair‐boat‐chair‐chair conformation. 27‐Nor‐ and 29‐noroxidosqaulenes ( 7 and 8 , respectively) were incubated with this enzyme to investigate the role of the methyl groups on 1 for the polycyclization cascade. Compound 7 afforded two enzymatic products, namely, 30‐norlanosterol ( 12 ) and 26‐normalabaricatriene ( 13 ; 12 / 13 9:1), which were produced through the normal chair‐boat‐chair‐chair conformation and an atypical chair‐chair‐boat conformation, respectively. Compound 8 gave two products 14 and 15 ( 14 / 15 4:5), which were generated by the normal and the unusual polycyclization pathways through a chair‐chair‐boat‐chair conformation, respectively. It is remarkable that the twist‐boat structure for the B‐ring formation was changed to an energetically favored chair structure for the generation of 15 . Surprisingly, 14 and 15 consisted of a novel 6,6,6,6‐fused tetracyclic ring system, thus differing from the 6,6,6,5‐fused lanosterol skeleton. Together with previous results, we conclude that the methyl‐29 group is critical to the correct folding of 1 , with lesser contributions from the other branched methyl groups, such as methyl‐26, ‐27, and ‐28. Furthermore, we demonstrate that the methyl‐29 group has a crucial role in the formation of the five‐membered D ring of the lanosterol scaffold. 相似文献
969.
Micellar inhibition effect of gangliosides on a degradation of drug was investigated, where ganglioside G(M1) (GM1), G(D1a) (GD1a) and G(T1b) (GTlb) whose sialic acid residue is one, two and three, respectively, were used. The base-catalyzed isomerization of prostaglandin A(2) (PGA(2)) to prostaglandin B(2) (PGB(2)) was chosen as a model experiment. The rate for the isomerization of PGA(2) was determined by measuring the concentration of PGA(2) (and PGB(2)) with a high-performance liquid chromatography. Gangliosides micelles inhibited the isomerization of PGA(2). The inhibition effect of GT1b micelles was larger than that of GD1a micelles. This result would be due to the larger absolute value of surface potential of GT1b micelles, which brings about a larger electrostatic repulsion between micellar surface and OH(-). The terminal sialic acid residue of ganglioside was effective to inhibit the isomerization of PGA(2). GM1 micelles without terminal sialic acid residue but with large aggregation number exhibited a superior steric shielding effect rather than an electrostatically repulsive effect. The inhibition effect of GM1 micelles was enhanced by the mixed micellization with the other ganglioside with a terminal sialic acid residue. GM1-GD1a or GM1-GT1b mixed micelles remarkably inhibited the isomerization of PGA(2). The physiological activity of PGs in the biological membranes containing gangliosides was also discussed. 相似文献
970.
Kyohei Shibano Reo Kontani Hiroshi Hirai Mikio Hasegawa Kazuyuki Aihara Hisao Taoka David McQuilkin Rikiya Abe 《The European physical journal. Special topics》2014,223(12):2611-2620
In recent years, practical research related to distributed power generation and networked distribution grids has been increasing. This research uses a relatively abstract model for the cost reduction in the Digital Grid Power Network. In the Digital Grid, the traditional wide-area synchronous grid is divided into smaller segmented grids which are connected asynchronously. In this paper, we demonstrate how to formulate the minimized cost of power generation by using linear programming methods, while considering the cost of electric transmission and distribution and using asynchronous power interchange among separate grids. 相似文献