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91.
Emanuele Miserazzi Mario Alessandro SpottiRoberto Profeta Simone SpadaArnaldo Nalin Elisa MoroDaniele Andreotti 《Tetrahedron letters》2011,52(3):448-452
An interesting and surprising rearrangement was observed during the reaction of 4-N-benzyl piperazinone derivatives with Lawesson’s reagent as a thionating agent. Investigation into the possible mechanism responsible for these results is reported herein. 相似文献
92.
Campos E Cordeiro R Santos AC Matos C Gil MH 《Colloids and surfaces. B, Biointerfaces》2011,88(1):477-482
Bi-soft segmented poly(ester urethane urea) microparticles were prepared and characterized aiming a biomedical application. Two different formulations were developed, using poly(propylene glycol), tolylene 2,4-diisocyanate terminated pre-polymer (TDI) and poly(propylene oxide)-based tri-isocyanated terminated pre-polymer (TI). A second soft segment was included due to poly(?-caprolactone) diol (PCL). Infrared spectroscopy, used to study the polymeric structure, namely its H-bonding properties, revealed a slightly higher degree of phase separation in TDI-microparticles. TI-microparticles presented slower rate of hydrolytic degradation, and, accordingly, fairly low toxic effect against macrophages. These new formulations are good candidates as non-biodegradable biomedical systems. 相似文献
93.
Riccardo?A.?Siliprandi Stefano?Zanini Elisa?Grimoldi Francesco?S.?Fumagalli Ruggero?BarniEmail author Claudia?Riccardi 《Plasma Chemistry and Plasma Processing》2011,31(2):353-372
An atmospheric pressure dielectric barrier plasma discharge has been used to study a thin film deposition process. The DBD
device is enclosed in a vacuum chamber and one of the electrodes is a rotating cylinder. Thus, this device is able to simulate
continuous processing in arbitrary deposition condition of pressure and atmosphere composition. A deposition process of thin
organosilicon films has been studied reproducing a nitrogen atmosphere with small admixtures of hexamethyldisiloxane (HMDSO)
vapours. The plasma discharge has been characterized with optical emission spectroscopy and voltage-current measurements.
Thin films chemical composition and morphology have been characterized with FTIR spectroscopy, atomic force microscopy (AFM)
and contact angle measurements. A strong dependency of deposit character from the HMDSO concentration has been found and then
compared with the same dependency of a typical low pressure plasma enhanced chemical vapour deposition process. 相似文献
94.
álvaro?Reyes-Carmona Ramón?Moreno-Tost Josefa?Mérida-Robles José?Santamaría-González Pedro?J.?Maireles-Torres Antonio?Jiménez-López Elisa?Moretti Maurizio?Lenarda Enrique?Rodríguez-CastellónEmail author 《Adsorption》2011,17(3):527-538
This work presents some applications of ZrO2 supported over SBA-15 silica as promoter of sulfated zirconia and as support from CuO/CeO2 catalytic system for preferential oxidation of CO to CO2 in hydrogen rich streams, used as feed for proton exchange membrane fuel cells (PEMFC). Different amounts of ZrO2, from 10 to 30 wt.% were incorporated. These prepared materials were characterized by powder XRD, adsorption-desorption of
N2 at 77 K, transmission and scanning electron microscopy (TEM and SEM) and X-rays photoelectron spectroscopy (XPS). The acidity
was studied by thermo-programmed desorption of ammonia (NH3-TPD). These materials were tested, after treatment with H2SO4, by 2-propanol dehydration and 1-butene isomerization catalytic tests. The samples were found quite good catalyst with strong
acid sites, the sample with 20 wt.% of ZrO2 being the better performing sample. Finally this material was successfully used as support for a CuO/CeO2 system, with 6 wt.% of Cu and 20 wt.% of Ce. The resulting catalyst was tested in the preferential oxidation of CO (CO-PROX)
attaining conversions close to 100% and high selectivity to CO2. 相似文献
95.
Travaglia A Arena G Fattorusso R Isernia C La Mendola D Malgieri G Nicoletti VG Rizzarelli E 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(13):3726-3738
There is a significant overlap between brain areas with Zn(2+) and Cu(2+) pathological dys-homeostasis and those in which the nerve growth factor (NGF) performs its biological role. The protein NGF is necessary for the development and maintenance of the sympathetic and sensory nervous systems. Its flexible N-terminal region has been shown to be a critical domain for TrkA receptor binding and activation. Computational analyses show that Zn(2+) and Cu(2+) form pentacoordinate complexes involving both the His4 and His8 residues of the N-terminal domain of one monomeric unit and the His84 and Asp105 residues of the other monomeric unit of the NGF active dimer. To date, neither experimental data on the coordination features have been reported, nor has one of the hypotheses according to which Zn(2+) and Cu(2+) may have different binding environments or the Ser1 α-amino group could be involved in coordination been supported. The peptide fragment, encompassing the 1-14 sequence of the human NGF amino-terminal domain (NGF(1-14)), blocked at the C terminus, was synthesised and its Cu(2+) and Zn(2+) complexes characterized by means of potentiometric and spectroscopic (UV/Vis, CD, NMR, and EPR) techniques. The N-terminus-acetylated form of NGF(1-14) was also investigated to evaluate the involvement of the Ser1 α-amino group in metal-ion coordination. Our results demonstrate that the amino group is the first anchoring site for Cu(2+) and is involved in Zn(2+) coordination at physiological pH. Finally, a synergic proliferative activity of both NGF(1-14) and the whole protein on SHSY5Y neuroblastoma cell line was found after treatment in the presence of Cu(2+). This effect was not observed after treatment with the N-acetylated peptide fragment, demonstrating a functional involvement of the N-terminal amino group in metal binding and peptide activity. 相似文献
96.
Palma E Correia JD Oliveira BL Gano L Santos IC Santos I 《Dalton transactions (Cambridge, England : 2003)》2011,40(12):2787-2796
Bone scintigraphy with (99m)Technetium-methylenediphosphonate ((99m)Tc-MDP) or (99m)Technetium-hydroxymethylenediphosphonate ((99m)Tc-HMDP) presents several limitations, namely low specificity, uncertainty in the radiopharmaceutical's molecular structure and long acquisition time after injection. Aiming to find bone-seeking radiotracers based on the core fac-[(99m)Tc(CO)(3)](+) with improved chemical and biological properties, we synthesized new conjugates (pz-PAM and pz-ALN), comprising a pyrazolyl-diamine chelating unit (pz: N,N,N donor atom set) for metal stabilization and a pendant pamidronate (PAM) or alendronate (ALN) moiety for bone targeting. The reaction of the conjugates with fac-[(99m)Tc(CO)(3)](+) yielded (> 95%) the stable complexes fac-[(99m)Tc(CO)(3)(pz-PAM)](-) (2a) and fac-[(99m)Tc(CO)(3)(pz-ALN)](-) (3a), which have been characterized by comparing their HPLC gamma-traces with the UV-vis traces of the Re surrogates 2 and 3, respectively. 2a and 3a bind strongly onto hydroxyapatite. The biodistribution studies in Balb-c mice have shown that 2a and 3a presented an high bone uptake (2a 18.3 ± 0.6% I.D./g, 3a 17.3 ± 6.1% I.D./g, at 1 h post injection), similar to (99m)Tc-MDP (17.1 ± 2.4% I.D./g, at 1 h post injection), with comparable clearance from most tissues and increased total excretion (2a 66% I.D., 3a 67% I.D. and (99m)Tc-MDP 49% I.D., at 1 h post injection). The bone-to-blood (2a 86.2, 3a 74.7) and the bone-to-muscle ratios (2a 77.7, 3a 79.0) are higher than the ones found for (99m)Tc-MDP (70.9, 47.9), at 4 h post injection. Planar whole-body gamma camera images of the rats injected with the (99m)Tc(CO)(3)-labeled pamidronate (2a) and alendronate (3a) confirmed the overall adequate biological profile of the new radiotracers for bone imaging. 相似文献
97.
Gallo FR Multari G Federici E Palazzino G Giambenedetti M Petitto V Poli F Nicoletti M 《Natural product research》2011,25(13):1261-1270
Equisetum arvense L. is a herbaceous medicinal plant, commonly known as horsetail, whose extracts have been reported to possess diuretic and haemostatic properties. The aim of this study was to evaluate the use of fingerprint chromatographic methods on commercially available raw materials or preparations of E. arvense L. in order to ascertain their quality and identify possible adulterants using HPLC and HPTLC densitometry. Two chromatographic methods were used to determine the chemical fingerprints of E. arvense and other allied species. The first was based on HPTLC identification followed by densitometric measurement at 350?nm. The second was based on HPLC separation. The ease of sample preparation and the possibility of simultaneous analysis of several samples in a short time make HPTLC a method of choice for the comprehensive quality evaluation of herbal products. 相似文献
98.
Mussardo P Corda E González-Ruiz V Rajesh J Girotti S Martín MA Olives AI 《Analytical and bioanalytical chemistry》2011,400(2):321-327
The interaction between DNA and several newly synthesized derivatives of the natural anticancer compound luotonin A has been
studied. The results from our work reveal an effective and selective alkaloid/double-stranded DNA (ds-DNA) interaction. In
the presence of increasing amounts of ds-DNA, a noticeable fluorescence quenching of the luotonin A derivatives under study
was observed. However, this effect did not take place when single-stranded DNA (ss-DNA) was employed. The association constant
alkaloids/ds-DNA was calculated by quantitation of such a quenching effect. The influence of other quenchers, namely Co2+ and Br− on the native fluorescence of luotonin A and derivatives was also studied, and a remarkable quenching effect was observed
for both ions. We have also investigated how by binding DNA the alkaloids could get protected from the external Co2+ and Br− quenchers. The Stern–Volmer constants (K
SV) for Co2+ and Br− quenching effect on the studied alkaloids were considerably reduced (10–50%) after incubation of the compounds in the presence
of DNA with regard to the K
SV values in absence of DNA. An increase in the fluorescence anisotropy values of luotonins was also produced only in the presence
of ds-DNA but not in the case of ss-DNA. To better characterize the nature of that interaction, viscosimetry assays and ethidium
bromide displacement studies were conducted. With regard to DNA reference solutions, the viscosity of solutions containing
DNA and luotonin A derivatives was reduced or not significantly increased. It was also observed that the studied compounds
were unable to displace the intercalating agent ethidium bromide. All of these results, together with the obtained association
constants values (K
ass = 2.2 × 102 – 1.3 × 103), support that neither covalent nor intercalating interactions luotonin A derivatives/ds-DNA are produced, leading to the
conclusion that these alkaloids bind ds-DNA through the minor groove. The specific changes in the fluorescence behavior of
luotonin A and derivatives distinguishing between ss-DNA and ds-DNA binding, lead us to propose these compounds as attractive
turn-off probes to detect DNA hybridization. 相似文献
99.
Donzello MP De Mori G Viola E Ercolani C Bodo E Mannina L Capitani D Rizzoli C Gontrani L Aquilanti G Kadish KM D'Angelo P 《Inorganic chemistry》2011,50(23):12116-12125
The solid state and solution structure of 2,3-dicyano-5,6-di(2-thienyl)-1,4-pyrazine, [(CN)(2)Th(2)Pyz], and its Pd(II) derivative, [(CN)(2)Th(2)Pyz(PdCl(2))(2)]·H(2)O, formed by reaction of [(CN)(2)Th(2)Pyz] with [(C(6)H(5)CN)(2)PdCl(2)] were characterized by X-ray, UV-visible, (1)H and (13)C NMR, and extended X-ray absorption fine structure (EXAFS) spectral measurements. The X-ray crystal structure of [(CN)(2)Th(2)Pyz] shows the presence of one thienyl ring positioned orthogonal to the rest of the molecule, with the two vicinal thienyl rings lying orthogonal to each other in a rare arrangement. NMR studies of [(CN)(2)Th(2)Pyz] in the solid state and in solutions of dimethylformamide or dimethyl sulfoxide confirm a nonequivalence of the thienyl rings in the solid state and also in solution. EXAFS results indicate that two distinct Pd(II) coordination sites are formed at the di(2-thienyl)pyrazino moiety of [(CN)(2)Th(2)Pyz(PdCl(2))(2)]·H(2)O, with identical Pd-N(pyz) (2.03(3) ?) and Pd-Cl (2.36(3) ?) bond lengths but with different Pd-S1 (2.25(4) ?) and Pd-S2 (3.21(5) ?) bond distances in an overall asymmetric molecular framework. Density functional theory (DFT) and time-dependent DFT (TDDFT) theoretical studies also provide information about the structure and spectral behavior of the precursor and its metalated Pd(II) derivative. (1)H/(13)C NMR and UV-visible spectral measurements were also carried out on two heteropentametallic porphyrazine macrocycles which were prepared by a reaction of PdCl(2) with [Th(8)TPyzPzM] where Th(8)TPyzPz = tetrakis-2,3-[5,6-di-(2-thienyl)-pyrazino]porphyrazinato dianion and M = Mg(II)(H(2)O) or Zn(II). Spectroscopic data on the newly synthesized [(PdCl(2))(4)Th(8)TPyzPzM] compounds suggest that the binding of PdCl(2) involves coordination sites of the type S(2(th))PdCl(2) with the two thienyl rings of each di(2-thienyl)pyrazino fragment bound to Pd(II) in an equivalent manner ("th-th" coordination). This is similar to what was found for the corresponding octapyridinated analogues ("py-py" coordination). 相似文献
100.
Lanucara F Chiavarino B Crestoni ME Scuderi D Sinha RK Maître P Fornarini S 《Inorganic chemistry》2011,50(10):4445-4452
Model ferric heme nitrosyl complexes, [Fe(TPP)(NO)](+) and [Fe(TPFPP)(NO)](+), where TPP is the dianion of 5,10,15,20-tetrakis-phenyl-porphyrin and TPFPP is the dianion of 5,10,15,20-tetrakis-pentafluorophenyl-porphyrin, have been obtained as isolated species by the gas phase reaction of NO with [Fe(III)(TPP)](+) and [Fe(III) (TPFPP)](+) ions delivered in the gas phase by electrospray ionization, respectively. The so-formed nitrosyl complexes have been characterized by vibrational spectroscopy also exploiting (15)N-isotope substitution in the NO ligand. The characteristic NO stretching frequency is observed at 1825 and 1859 cm(-1) for [Fe(III)(TPP)(NO)](+) and [Fe(III)(TPFPP)(NO)](+) ions, respectively, providing reference values for genuine five-coordinate Fe(III)(NO) porphyrin complexes differing only for the presence of either phenyl or pentafluorophenyl substituents on the meso positions of the porphyrin ligand. The vibrational assignment is aided by hybrid density functional theory (DFT) calculations of geometry and electronic structure and frequency analysis which clearly support a singlet spin electronic state for both [Fe(TPP)(NO)](+) and [Fe(TPFPP)(NO)](+) complexes. Both TD-DFT and CASSCF calculations suggest that the singlet ground state is best described as Fe(II)(NO(+)) and that the open-shell AFC bonding scheme contribute for a high-energy excited state. The kinetics of the NO addition reaction in the gas phase are faster for [Fe(III)(TPFPP)](+) ions by a relatively small factor, though highly reliable because of a direct comparative evaluation. The study was aimed at gaining vibrational and reactivity data on five-coordinate Fe(III)(NO) porphyrin complexes, typically transient species in solution, ultimately to provide insights into the nature of the Fe(NO) interaction in heme proteins. 相似文献