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991.
Quinoline is known to adsorb on a mercury electrode surface with several differentorientations and it sometimes blocks other electrochemical reactions. The Ramanmicroprobe technique has been applied successfully to observe reorientations ofquinoline adsorbed on the mercury surface from neutral and basic aqueoussolutions. The orientation-distance profile from the mercury surface was also studied.A Raman band intensity of quinoline (1373 cm–1) relative to the intensity ofperchlorate ion (931 cm–1) was measured. The peak positions did not shift evenwhen the applied potential was altered, but the relative peak intensity changed.It was concluded that the adsorbed quinoline changes its orientation from a flatat –0.1 > E > –0.3V, to a standing at E < –0.5 V, passing through a mixtureof the two orientations when –0.3 > E > –0.5 V. 相似文献
992.
Fumi Yoshida Hiroki Yoshinaka Dr. Hidenori Tanaka Dr. Shinya Hanashima Dr. Yoshiki Yamaguchi Mikio Ishihara Miyuki Saburomaru Yuki Kato Risa Saito Dr. Hiromune Ando Dr. Makoto Kiso Dr. Akihiro Imamura Dr. Hideharu Ishida 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(3):796-805
The chemical synthesis of the highly branched core oligosaccharides of lipooligosaccharides (LOSs) found in Campylobacter jejuni, which causes Guillain–Barré syndrome by a preceding infection, is described. The target LOS mimics, consisting of eight or nine monosaccharides, were classified into three groups as key building blocks: ganglioside-core tetra-/pentasaccharides (GM1-/GD1a-like), l -glycero-d -manno-heptose-containing trisaccharides, and 3-deoxy-d -manno-2-octulosonic acid (KDO) residues. These synthetic fragments were obtained from commercially available monosaccharides. Less obtainable l -glycero-d -manno-heptose and KDO residues, as key components of the LOSs, were synthesized from p-methoxyphenyl d -mannoside and di-O-isopropylidene-protected d -mannose, respectively. The synthesis of α-KDO glycoside, as one of the most difficult stereocontrolled glycosidic constructions, was achieved by treating a 2,3-ene derivative of KDO with phenylselenyl trifluoromethanesulfonate as a suitable α-directing reagent. All synthetic blocks were constructed through a convergent synthetic route, which resulted in the first synthesis of structurally challenging LOS core glycans containing ganglioside GM1 and GD1a-core sequences. 相似文献
993.
Kazuhiro Haraguchi Hiroki Kumamoto Kiju Konno Hideki Yagi Yutaka Tatano Yuki Odanaka Satoko Shimbara Matsubayashi Robert Snoeck Graciela Andrei 《Tetrahedron》2019,75(33):4542-4555
4′-Azido- (7), 4′-C-fluoromethyl- (8) 4′-C-ethynyl- (9) and 4′-C-cyano- (10) 2′-deoxy-4′-thiocytidines have been synthesized. In this study, it was found that the isolated yield of 4′-thiouracil nucleoside 13 in a Lewis acid-promoted Vorbrüggen-type glycosidation utilizing 12 was better than that of the electrophilic glycosidation reaction between silylated uracil and 11. This improved result prompted us to perform the glycosidation utilizing 36 and 43 for the synthesis of 37 and 44. Introduction of the azido group was carried out by nucleophilic substitution in the 4′-benzoyloxy derivative 22a. On the other hand, 9 and 10 were synthesized by way of the chemical manipulation of the hydroxymethyl group at the 4′-position of 46.Evaluation of the antineoplastic activity of 2 and 7–10 against human B-cell (CCRF-SB) and T-cell leukemia (Molt-4) cell lines revealed that 4′-azido- (7) and 4′-C-fluoromethyl- (8) derivatives exhibited cytotoxic activity whereas no cytotoxicity was observed in the 4′-C-ethynyl- (9) and 4′-C-cyano- (10) derivatives as well as the parent compound 2. Compound 7 was also found to possess promising antiviral activity against VZV and HSV-1 without any cytotoxity against HEL host cells. It is noteworthy that 7 exhibited potent inhibitory activities against the thymidine kinase-deficient (TK?) mutant of VZV and HSV-1. 相似文献
994.
Umezu Yuta Shimizu Yusuke Masuda Hiroki Ninomiya Yoshiyuki 《Annals of the Institute of Statistical Mathematics》2019,71(2):247-274
Annals of the Institute of Statistical Mathematics - Non-concave penalized maximum likelihood methods are widely used because they are more efficient than the Lasso. They include a tuning parameter... 相似文献
995.
996.
In the present study, the usability of semiempirical quantum mechanical methods for calculating bond dissociation energy (BDE) was investigated systematically. Density functional theory (DFT) methods with the B3LYP and B97-1 functionals were used for comparison. We introduced a new test set for BDE, called BDE200, which covers a wide range of compounds including large aromatic compounds. The use of BDE200 test set revealed that the accuracy of the methods studied was ordered from best to worst as: B97-1 > B3LYP > rPM6 >> PM7 > PM6 > AM1 > PM3. In addition to the improved accuracy of rPM6 for predicting BDE, it was found that rPM6 can provide a quantitative correlation between BDE values and reactivity. The rPM6 calculated activation enthalpies for C–H hydroxylation catalysed by the compound I of cytochrome P450 were proportional to the calculated and experimental C–H BDE values, in line with the results of previous DFT studies. We believe that rPM6 can help develop a database, for instance, for the determination of site of metabolism. 相似文献
997.
Hiroki Sato Michelle A. Blemker Garrett Hellinghausen Prof. Daniel W. Armstrong Jordan W. Nafie Prof. Sean T. Roberts Prof. Michael J. Krische 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(37):8719-8724
Cyclometalation of a triple helical N-doped phenylene cage prepared by ruthenium(0)-catalyzed diol–diene benzannulation delivers a chiral, conformationally constrained Ir(ppy)3 analogue. Like the parent complex, fac-Ir(ppy)3, the iridium-containing PAH-cage is phosphorescent, but displays enhanced resistance to oxygen quenching. 相似文献
998.
Guanting Liu Prof. Hisahiro Sasabe Kengo Kumada Hiroki Arai Prof. Junji Kido 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(48):e202201605
In this study, we synthesized and characterized multiresonant thermally activated delayed fluorescent (TADF) materials embedded with nitrogen-boron-oxygen (N−B−O), exhibiting color-tunability between blue and green, namely NBO , m-DiNBO , and p-DiNBO . The three emitter materials showed a high photoluminescence quantum yield (PLQY) and a state-of-the-art narrow full width at half maximum (FWHM) of 96 %/25 nm, 87 %/17 nm, and 99 %/19 nm, respectively. For m-DiNBO and p-DiNBO , the emission color could be tuned from blue to green by regulating the nonbonding/bonding molecular orbital characters. Owing to the expanded planar molecular structure, m-DiNBO and p-DiNBO showed high horizontal dipole ratio (Θ) of 88 % and 92 %, respectively. OLEDs were prepared with NBO , m-DiNBO , and p-DiNBO , exhibiting high external quantum efficiencies of 16.8 %, 24.2 %, and 21.6 %, respectively. NBO and m-DiNBO exhibited pure-blue emission with CIE coordinates of (0.137, 0.142) and (0.126, 0.098), respectively. p-DiNBO showed pure-green emission with a CIE coordinate of (0.258, 0.665). 相似文献
999.
1000.
The absorbance using diffuse reflectance in the polarization spectroscopy was expressed using the empirical expressions that fitted the Monte Carlo simulation results. The absorbance spectra of glucose solutions indicated that the partition among H2O molecular species changed partly to the other ones depending on the glucose content. In saline water and phosphate-buffered saline water, there appears an action opposite to the transition in dissolution of glucose by the destruction of water species due to the presence of Na+ and Cl? ions. The sensitivity of glucose concentration in them was found to be higher in the cross-polarization than in the parallel one owing to the increased travelling distance caused by multiscattering. 相似文献