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91.
The interaction of Me2Sn(IV)2+ and Me3Sn(IV)+ with a prodrug, sodium 2-mercaptoethane sulfonate (HSCH2CH2SO3Na, MESNA) abbreviated as (HL), has been studied potentiometrically in aqueous solution (I = 0.1 mol·L?1 KNO3, 298 K). The concentration distribution of various species formed in the solution was studied with changes in pH (~3–11). A strong coordination of MESNA with metal through the S atom of thiol group has been found. In the Me2Sn(IV)–HL system, the species [Me2Sn(L)]+ (53.1–75.6%) is predominant at acidic pH (3.73 ± 0.02) and the species [Me2Sn(L)2OH]? (29.4–38.5%) is predominant at basic pH (10.32 ± 0.08). In contrast, for the Me3Sn(IV)+ system, [Me3SnL] (37.0–57.4%) is the major species at pH 7.65 ± 0.03 and [Me3Sn(OH)] (49.9–67.2%) and [Me3Sn(L)(OH)]? (30.2–46.5%) are the major species at pH 11.05 ± 0.01. However, at physiological pH (7.01 ± 0.32), in both (1:1) and (1:2) Me2Sn(IV)–HL systems, the species [Me2Sn(L)(OH)] (67.2–89.9%) is predominant, whereas for Me3Sn(IV)–HL (1:1) and (1:2) systems, [Me3Sn(OH)] (53.5%) and [Me3SnL] (56.8%) are the respective predominant species. In order to characterize the possible geometry of the proposed complex species, multinuclear (1H, 13C and 119Sn) NMR studies were carried out at different pHs. No polymeric species were detected in the experimental pH range. 相似文献
92.
Similarity solutions for the flow of a non-ideal gas behind a strong exponential shock driven out by a piston (cylindrical
or spherical) moving with time according to an exponential law are obtained. Similarity solutions exist only when the surrounding
medium is of constant density. Solutions are obtained, in both the cases, when the flow between the shock and the piston is
isothermal or adiabatic. It is found that the assumption of zero temperature gradient brings a profound change in the density
distribution as compare to that of the adiabatic case. Effects of the non-idealness of the gas on the flow-field between the
shock and the piston are investigated. The variations of density-ratio across the shock and the location of the piston with
the parameter of non-idealness of the gas are also obtained. 相似文献
93.
Y. Nath 《International Journal of Non》1982,17(4):285-296
The von Kármán type partial differential equations governing non-linear dynamic behaviour of circular plates resting on Winkler and Pasternak elastic foundations have been analysed analytically. The space and time-wise integrations have been carried out employing the Chebyshev polynomials and implicit Houbolt techniques, respectively. The influence of foundation parameters K and G on the large amplitude response of circular plates subjected to step function loads has been studied for both the clamped immovable as well as simply supported immovable edge conditions. Foundation parameters K and G have been determined for the minimax central response. For all values of K,values of G should be between 30 and 40 for the clamped circular plates and the value of G should be a maximum for the simply supported circular plates. 相似文献
94.
Sanjay K. Bharti Saurabh K. Patel Gopal Nath Ragini Tilak Sushil K. Singh 《Transition Metal Chemistry》2010,35(8):917-925
Six Cu(II) complexes of Schiff base ligands of arylidene-2-(4-(4-bromo/methoxy-phenyl)thiazol-2-yl) hydrazines have been synthesized,
characterized and screened for DNA cleavage and antimicrobial activities. The chemical structures of the complexes were deduced
by physicochemical and spectroscopic methods. Elemental analyses indicated that the stoichiometry of the complexes is CuL2 (L = Schiff base ligand). The DNA cleavage activities of the complexes were evaluated by agarose gel electrophoresis in the
presence and absence of oxidant (H2O2) and free radical scavenger (DMSO). All the six complexes showed significant nuclease activity in the presence of H2O2, and two of the complexes showed moderate nuclease activity even in the absence of oxidant. The complexes did not show nuclease
activity in the presence of free radical scavenger. The compounds were tested for activity against selected bacteria and fungi. 相似文献
95.
Kinsuk Das Tarak Nath Mandal Somnath Roy Samik Gupta Anil Kumar Barik Partha Mitra Arnold L. Rheingold Susanta Kumar Kar 《Polyhedron》2010
The varying coordination modes of the title ligand, L [5-methyl-1-(pyridin-2-yl)-N′-[pyridin-2-ylmethylidene]pyrazole-3-carbohydrazide] towards the different metal centers is reported by preparation and characterization of Cu(II), Zn(II) and Cd(II) complexes, [Cu(L)NO3.H2O](NO3) (1) [Zn(L)2](ClO4)2·2DMF (2) and [Cd(L)(I)2] (3) respectively. In 1, the neutral ligand serves as tetradentate 4 N donor where both pyridine and pyrazole nitrogen atoms of pyridyl–pyrazole part are coordinatively active, leaving the carbonyl oxygen of the carbohydrazide part inactive. The same pyridine and pyrazole N atoms remain abstained from the coordination process towards the Zn(II) and Cd(II) metal centers. For 2 and 3 the ligand behaves as a tridentate NNO donor where the two nitrogen atoms come from azomethine, pyridine of pyridine-2-carbaldehyde parts and O from carbonyl oxygen atoms (carbohydrazide part). The complex 1 and 2 are distorted octahedral while complex 3 adopts distorted square pyramidal geometry. All the complexes are X-ray crystallographically characterized. 相似文献
96.
97.
Tri-state logic plays a significant role in carry free arithmetical operation. Design of all-optical scheme of three basic tri-state logical operation (NOT, AND, OR) with the help of polarization encoded semiconductor optical amplifier (SOA)-assisted Sagnac interferometric switch has been studied and investigated in this present paper. Numerical simulation is also presented, which verifies the theoretical results. Insertion loss, contrast ratio, extinction ratio, amplitude modulation, bit error rate and signal to noise ratio values have also been analyzed. 相似文献
98.
Kumar Nagesh Varma G. D. Nath R. Srivastava A. K. 《Applied Physics A: Materials Science & Processing》2011,104(4):1169-1174
In this paper we report a simple method that enables the easy fabrication of ordered ZnO nanowire arrays using Anodic Aluminium
Oxide (AAO) template. We have used a vacuum injection technique to fill solution into the pores of an AAO template. The AAO
template has been fabricated by a two-step anodization process using 0.3 M oxalic acid (H2C2O4) solution under a constant voltage of 40 V. The AAO template formed through this process has been detached from Al substrate
via an anodic voltage pulse using perchloric acid (HClO4) solution (70%). The nanowires of ZnO have been synthesized by injecting the saturated Zn(NO3)2 solution into the pores of the detached AAO template using a vacuum pump. The ZnO nanowires synthesized by this technique
have been found dense & continuous with uniform diameter throughout the length of the wire. The structural characteristics
of AAO template and ZnO nanowires have been studied by Field Emission Scanning Electron Microscope (FESEM), Atomic force microscope
(AFM) and Transmission Electron Microscope (TEM). 相似文献
99.
Sukanta Kumar DashAmar Nath Samanta Syamalendu S. Bandyopadhyay 《Fluid Phase Equilibria》2011,307(2):166-174
In this work, new experimental results of the vapour-liquid equilibrium (VLE) of CO2 in aqueous 2-amino-2-methyl-1-propanol (AMP) and piperazine (PZ) have been presented in the temperature range of 298-328 K and PZ concentration range of 2-8 mass%, keeping the total amine concentration in the solution at 30 mass%. The partial pressures of CO2 were in the range of 0.1-1450 kPa. A thermodynamic model was developed to correlate and predict the VLE of CO2 in aqueous AMP + PZ. The electrolyte nonrandom two liquid (ENRTL) theory has been used to develop the VLE model for the quaternary system (CO2 + AMP + PZ + H2O) to describe the equilibrium behaviour of the solution. The experimental data from this work and data available in the literature were used to regress the ENRTL interaction parameters. The model predictions are in good agreement with the experimental data of CO2 solubility in aqueous blends of this work as well as those reported in the literature. The current model can also predict speciation, heat of absorption, pH of the CO2 loaded solution, and amine volatility. 相似文献
100.
The degradation of neurotransmitters is a hallmark feature of Alzheimer''s disease (AD). Copper bound Aβ peptides, invoked to be involved in the pathology of AD, are found to catalyze the oxidation of serotonin (5-HT) by H2O2. A combination of EPR and resonance Raman spectroscopy reveals the formation of a Cu(ii)–OOH species and a dimeric, EPR silent, Cu2O2 bis-μ-oxo species under the reaction conditions. The Cu(ii)–OOH species, which can be selectively formed in the presence of excess H2O2, is the reactive intermediate responsible for 5-HT oxidation. H2O2 produced by the reaction of O2 with reduced Cu(i)–Aβ species can also oxidize 5-HT. Both these pathways are physiologically relevant and may be involved in the observed decay of neurotransmitters as observed in AD patients.The mononuclear copper hydroperoxo species (Cu(ii)–OOH) of Cu–Aβ is the active oxidant responsible for serotonin oxidation by Cu–Aβ in the presence of physiologically relevant oxidants like O2 and H2O2, which can potentially cause oxidative degradation of neurotransmitters, a marker of Alzheimer''s disease. 相似文献