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91.
Metallosupramolecular Structures Derived from a Series of Diphosphine‐bridged Digold(I) Metalloligands with Terminal d‐Penicillamine 下载免费PDF全文
In this report, we describe our recent work on the development of a new family of chiral heteroleptic digold(I) metalloligands with mixed diphosphine and d ‐penicillaminate (d ‐pen), [Au2(dppx)(d ‐pen‐S)2]2– (dppx = PPh2(CH2)nPPh2, n = 1–5) and their application for the construction of chiral multinuclear and metallosupramolecular structures. The reactions of the metalloligands with 3d metal ions produce a variety of chiral heterobimetallic structures retaining the digold(I) metalloligand structure, ranging from discrete trinuclear to infinite helix structures that depend on the type of dppx. In addition, monophosphine and triphosphine analogues of the metalloligands were designed, and their coordination behavior is discussed to show the essential properties and potential extensibility of this class of metalloligands. 相似文献
92.
Dirhodium(II) tetrakis[N-tetrafluorophthaloyl-(S)-tert-leucinate], Rh2(S-TFPTTL)4, is an exceptionally efficient catalyst for enantioselective aminations of silyl enol ethers derived from acyclic ketones or alpha,beta-enones with [N-(2-nitrophenylsulfonyl)imino]phenyliodinane (NsN=IPh), providing N-(2-nitrophenylsulfonyl)-alpha-amino ketones in high yields and with enantioselectivities of up to 95% ee. The effectiveness of the present catalytic protocol has been demonstrated by an asymmetric formal synthesis of (-)-metazocine. 相似文献
93.
Fourier transform infrared (FTIR) spectroscopy is a powerful method to investigate the structures of key Tyr residues involved in various protein reactions. In this study, we have performed density functional theory (DFT) calculations for various hydrogen-bonded complexes of p-cresol, a simple model of a Tyr side chain, in different hydrogen-bond forms to develop explicit criteria for determining the hydrogen-bond structures of Tyr using FTIR spectroscopy. The CO stretching (nuCO) and COH bending (deltaCOH) vibrations were focused as markers and calculated results were compared with experimental data of p-cresol and Tyr. The calculated and experimental nuCO frequencies appeared at 1280-1260, 1260-1250, 1255-1235, and 1240-1220 cm-(1) in the hydrogen-bond donor, free, donor-acceptor, and acceptor forms, respectively. These frequencies, which showed little overlap between the individual hydrogen-bond forms, had a negative linear correlation with the CO lengths in optimized geometries. The deltaCOH frequencies were found at 1255-1210 cm-(1) in the donor form, while the free and acceptor forms showed relatively low deltaCOH frequencies at 1185-1165 and 1190-1160 cm-(1), respectively. In the donor-acceptor form, the vibrational mode with a considerable deltaCOH contribution was found at 1280-1255 cm-(1) with a weak IR intensity. This frequency and the nuCO frequency in the donor-acceptor form are similar to the nuCO and deltaCOH frequencies, respectively, of the donor form, making it difficult to discriminate the two forms. These two forms can be clearly distinguished by detecting a strong nuCO(D) band in p-cresol-OD or Tyr-OD, in which the deltaCOD vibration largely downshifts to approximately 1000 cm-(1). The nuCO(D) frequency of the donor-acceptor form was found at 1260-1240 cm-(1), while that of the donor form was at 1270-1255 cm-(1). Practically, plotting the frequency of the lower-frequency strong IR band (nuCO of the donor-acceptor form or deltaCOH of the donor form) of undeuterated species against the nuCO(D) frequency is convenient for accurate discrimination. Because the donor form shows a positive linear correlation between deltaCOH and nuCO(D) frequencies, the two forms exhibited distinct areas in this plot. The effects of hydrogen-bond interactions on other potential IR and Raman markers are also discussed. 相似文献
94.
95.
The reaction of a mixture of 2-(1-naphthyl)benzothiazoline (HL1) and 2,6-diphenylbenzo[1,2-d:4,5-d']bisthiazoline (H3L2) with nickel(II) acetate tetrahydrate yielded three kinds of square-planar nickel(II) complexes: one nickel(II) complex with innocent ligands ([Ni(L1)2] (1c)) and two nickel(II) complexes with non-innocent ligands ([Ni(L1-L1)] (1a) and [Ni(L1-L2)] (1b)). The complex 1c has two bidentate-N,S ligands, which are formed via ring opening of HL1. On the other hand, the two complexes 1a and 1b contain a tetradentate-N2S2 ligand, which is created via ring opening of HL1 and H3L2, followed by bond formation between imino carbon atoms. Complexes 1a and 1b show very intense absorptions in the near-infrared (NIR) region, characteristic of square-planar complexes with non-innocent ligands. The third nickel(II) complex having a non-innocent tetradentate-N2S2 ligand ([Ni(L2-L2)] (2)) was prepared from H3L2 and nickel(II) acetate tetrahydrate. The electronic spectrum of 2 exhibits a very intense absorption at 981 nm (epsilon = 3.6 x 10(4) M-1 cm-1), which is significantly red-shifted compared with those of 1a (837 nm and 4.4 x 10(4) M-1 cm-1) and 1b (885 nm and 4.5 x 10(4) M-1 cm-1), indicating the presence of an extended pi delocalization. The reaction of 2,6-bis(3,5-dichlorophenyl)benzo[1,2-d:4,5-d']bisthiazoline (H3L3) with nickel(II) acetate tetrahydrate also led to the formation of a nickel(II) complex with a non-innocent ligand ([Ni(L3-L3)] (3)). While complex 3 is analogous to 2, its electrical conductivity is much higher than that of 2. The molecular structures of 1b, 1c, 2, and 3 were determined by X-ray crystallography. 相似文献
96.
Nakamura H Abe Y Koizumi R Suzuki K Mogi Y Hirayama T Karube I 《Analytica chimica acta》2007,602(1):94-100
A new chemiluminescence biochemical oxygen demand (BODCL) determining method was studied by employing redox reaction between quinone and Baker's yeast. The measurement was carried out by utilizing luminol chemiluminescence (CL) reaction catalyzed by ferricyanide with oxidized quinone of menadione, and Saccharomyces cerevisiae using a batch-type luminometer. In this study, dimethyl sulfoxide was used as a solvent for menadione. After optimization of the measuring conditions, the CL response to hydrogen peroxide in the incubation mixture had a linear response between 0.1 and 100 μM H2O2 (r2 = 0.9999, 8 points, n = 3, average of relative standard deviation; R.S.D.av = 4.22%). Next, a practical relationship between the BODCL response and the glucose glutamic acid concentration was obtained over a range of 11-220 mg O2 L−1 (6 points, n = 3, R.S.D.av 3.71%) with a detection limit of 5.5 mg O2 L−1 when using a reaction mixture and incubating for only 5 min. Subsequently, the characterization of this method was studied. First, the BODCL responses to 16 pure organic substances were examined. Second, the influences of chloride ions, artificial seawater, and heavy metal ions on the BODCL response were investigated. Real sample measurements using river water were performed. Finally, BODCL responses were obtained for at least 8 days when the S. cerevisiae suspension was stored at 4 °C (response reduction, 69.9%; R.S.D. for 5 testing days, 18.7%). BODCL responses after 8 days and 24 days were decreased to 69.9% and 35.8%, respectively, from their original values (R.S.D. for 8 days involving 5 testing days, 18.7%). 相似文献
97.
98.
The high pressure behavior of gallium phosphide, GaP, has been examined using the synchrotron X-ray diffraction technique in a diamond anvil cell up to 27?GPa and 900?K. The transition from a semiconducting to a metallic phase was observed. This transition occurred at 22.2?GPa and room temperature, and a negative dependence of temperature of this transition was found. The transition boundary was determined to be P (GPa)?=?22.6???0.0014?×?T (K). 相似文献
99.
Fast ring opening of mesoionic 1,3-dioxolium-4-olates, generated by Rh(2)(OAc)(4)-catalyzed decomposition of phenyldiazoacetic anhydride derivatives, to acyloxyphenylketenes was demonstrated by trapping the ketenes with several ketenophiles. Reactions of phenyldiazoacetic anhydride derivatives with several ketenophiles such as dihydrofuran, carbodiimides, and imines were carried out. No 1,3-dipolar cycloadducts of the latter with 1,3-dioxolium-4-olates were observed. Instead, only their [2 + 2]-cycloadducts with the acyloxyketenes generated by ring-opening of the initially formed 1,3-dioxolium-4-olates were isolated. In the reaction with cyclopentadiene, 1,3-dipolar cycloadducts with 1,3-dioxolium-4-olates were formed as main products along with the [2 + 2]-ketene adduct. PM3 calculation of heats of formation of 2,5-diphenyl-1,3-dioxolium-4-olate and the corresponding benzoyloxyphenylketene indicates that the ring-opened acyloxyketenes are ca. 9 kcal/mol more stable than the corresponding 1,3-dioxolium-4-olates. 相似文献
100.
Hara T Hirayama F Arima H Yamaguchi Y Uekama K 《Chemical & pharmaceutical bulletin》2006,54(3):344-349
2-(N-Cyanoimino)-5-[(E)-4-styrylbenzylidene]-4-oxothiazolidine (FPFS-410) is a newly synthesized thiazolidine derivative having not only antidiabetic but also lipid-lowering activities. However, this compound has an extremely low aqueous solubility (2.8 (+/-0.33) x 10(-8) M (0.0094+/-0.0011 microg/ml) in 1.0 M phosphate buffer (pH 7.0) at 25 degrees C). In this study, we investigated the effect of various hydrophilic cyclodextrins (CyDs) on the solubility of FPFS-410 to select a CyD suitable for formulations of the compound. Among various CyDs, 2-hydroxypropyl-beta-CyD (HP-beta-CyD) had the highest solubilizing ability to FPFS-410, e.g., the solubility of the compound was increased 200000-fold by the addition of 40 mM HP-beta-CyD, which was attributable to the formation of the 1 : 2 (guest : host) inclusion complexes. The interaction of HP-beta-CyD with FPFS-410 was studied using 1H-nuclear magnetic resonance (NMR) spectroscopies including ROESY spectroscopy and a molecular modeling calculation. These results suggested that HP-beta-CyD forms a 1:2 (guest : host) inclusion complex with FPFS-410 by including both the stilbene and thiazolidine moieties. FPFS-410/HP-beta-CyD solid complexes with various stoichiometries were prepared by the spray drying and cogrinding methods, and confirmed by powder X-ray diffractometry that these complexes are in an amorphous state. The dissolution of FPFS-410 in water was significantly accelerated by the complexation with HP-beta-CyD. In vivo studies revealed that HP-beta-CyD markedly increases the bioavailability of FPFS-410 after oral administration in dogs. The present results suggest that HP-beta-CyD is useful for improvement of the extremely low bioavailability of FPFS-410. 相似文献