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141.
Seven organo‐bridged bis[tris(arylchalcogenolato)tin] compounds with the general formulae (R′E)3Sn–R–Sn(ER′)3 (R = –(CH2)4–, 1,4‐bis(methyl)benzene, 4,4′‐bis(methyl)biphenyl; R′ = Ph, 1‐Np, 2‐Np; E = S, Se) were synthesized and characterized by means of X‐ray diffractometry as well as NMR spectroscopy. Three different conformations of the arylchalcogenolato groups ER′ with respect to the bridging group R were rationalized and explained by means of quantum chemical investigations. 相似文献
142.
Tin oxalate as a precursor of tin dioxide and electrode materials for lithium-ion batteries 总被引:2,自引:0,他引:2
R. Alcántara Fernández F. Madrigal P. Lavela C. Pérez-Vicente J. Tirado 《Journal of Solid State Electrochemistry》2001,6(1):55-62
Tin(II) oxalate was studied as a novel precursor for active electrode materials in lithium-ion batteries. The discharge of
lithium cells using tin oxalate electrodes takes place by three irreversible steps: tin reduction, forming a lithium oxalate
matrix; solvent decomposition to form a passivating layer; and oxalate reduction in a two-electron process. These are followed
by reversible alloying of tin with lithium, leading to a maximum discharge of 11 F/mol. Cycling of the cells showed reversible
capacities higher than 600 mAh/g during the first five cycles and ca. 200 mAh/g after 50 cycles. Tin oxalate was converted
to tin dioxide by thermal decomposition at 450 °C and also by a chemical method by dissolving tin oxalate powder in 33% v/v
hydrogen peroxide at room temperature. The ultrafine nature of the tin dioxide powders obtained by this procedure allow their
use as electrodes in lithium cells. The best capacity retention during the first five cycles was achieved for a sample heat
treated to 250 °C to eliminate surface water.
Electronic Publication 相似文献
143.
Tungsten trioxide and two types of tin dioxide were compacted at different pressures and then sintered at different temperatures
in order to study how the microstructure formed is dependent on these parameters. The structures were studied using dilatometric
and porosimetric techniques and also using electron microscopy. X-ray diffraction was used to ascertain the completeness of
the decomposition reaction of SnSO4 being converted to SnO2. Tin dioxide, which was prepared from tin sulphate by calcining, was characterised by a large specific surface area. For
all three materials studied the mean pore size was found to increase and the specific surface area was found to decrease with
increasing sintering temperature. In the case of WO3 the total pore volume decreased markedly as the sintering temperature was increased from 900 to 1000° C. However, in the
case of SnO2, the total pore volume remained almost constant in the sintering temperature range of 600 to 1500° C. In the case of SnO2 derived from SnSO4 the sintered density was about 45% of the theoretical value while for the conventionally made SnO2 the sintered density was about 55% of the theoretical value. The sintered density of WO3 was found to show a marked increase, from 55% to 70% of the theoretical value, as the sintering temperature was raised from
1000 to 1100° C. 相似文献
144.
A novel gas-sensing system based on a dynamic nonlinear response is reported to enhance the selectivity toward sample gases using a single detector. A periodic temperature change was applied to a semiconductor gas sensor and the resulting conductance of the sensor was evaluated by fast Fourier transformation (FFT). The dynamic nonlinear response to the sample gases was further characterized depending on the frequency of the temperature change. The characteristic sensor response under the application of a temperature change was theoretically simulated by considering the kinetics of gas molecules on the semiconductor surface. 相似文献
145.
The optical properties of a silver-doped phosphate glass have been monitored during thermal processing at several fixed temperatures by in situ optical microspectroscopy. Silver nanoparticle (NP) formation and growth processes were assessed by analysis of surface plasmon resonance spectral features. Nucleation and growth processes were distinguished, which appeared temperature and time dependent. While nucleation was favored at low temperatures, relatively high temperatures promoted NP growth by silver diffusion. Photoluminescence spectra acquired along with optical absorption data indicated a continuous reduction of Ag+-Ag0 pairs concomitant with NP precipitation, suggesting their role as nucleation centers. The work of Ag NP formation and the activation energy for silver diffusion were estimated. 相似文献
146.
N. Stojilovic 《Applied Surface Science》2005,252(5):1806-1811
The near-surface region of Zircaloy-4 (Zry-4) has been probed using Auger electron spectroscopy (AES). In particular, the behavior of impurity (sulfur) and alloying (tin) elements has been monitored as a function of annealing temperature and time. High-temperature AES experiments above 900 K are reported, with a primary focus on changes in the S(LMM) Auger feature that overlaps with the primary Zr(MNV) transition. We find that the sulfur content of the near-surface region increases linearly with annealing time at higher temperatures. Tin is the only alloying element whose Auger signal intensity significantly exceeds the noise level at these temperatures. 相似文献
147.
Methyltin mercaptide is widely used as one of the best heat stabilizer in the polyvinylchloride (PVC) thermal processing due to its excellent stability, good transparency, high compatibility and weather resistance. The content of sulfur and tin significantly affects its quality and performance, so it is of great significance to develop an analytical method for the simultaneous determination of sulfur and tin. Inductively coupled plasma atomic emission spectrometry (ICP-OES) has been a powerful analytical tool for a myriad of complex samples owing to its advantages of the low detection limits, rapid and precise determinations over wide dynamic ranges, freedom from chemical inter-element interferences, the high sample throughput and above all, simultaneous multi-elements analysis. Microwave technique as a well-developed method for sample preparation can dramatically reduce the digestion time and the loss of volatile elements compared with the traditional open digestion. Hereby, a microwave-assisted acid digestion (MW-AAD) procedure followed by inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis was developed for the simultaneous determination of Sn and S in methyltin mercaptide. This method has the advantages of simplicity, rapidness, good accuracy, green and less use of samples. Parameters affecting the MW-AAD such as the digestion solution and digestion time were optimized by using a chemical analyzed reference sample (DX-181) to attain tin and sulfur quantitative recoveries. HNO3-HCl-HClO4(v/v/v=9 : 3 : 1) and 10 min were the optimum digestion solution and digestion time, respectively. Under optimum conditions, the standard addition method and the standard calibration curve method were both been used to detect Sn and S in DX-181. There was no significant difference between two methods and the relative deviations to the chemical analysis values were both less than 2%. Additionally, the accuracy of the MW-AAD method was examined by analyzing three methyltin mercaptide samples (DX-181, DX-990, DX-960). The results were satisfactory with the relative deviations (<3%) and the recoveries of standard addition (99%-102%). 相似文献
148.
Novel intermediates based on the Corey skeleton for preparation of the ω-chain of non-halogenated unnatural prostaglandin analogues containing a triple bond at position 13–14 (PG numbering) were synthesized. The utilization of a novel synthetic approach towards a new tin intermediate, and subsequent Stille coupling opens up new possibilities for preparing these important pharmaceutical intermediates. 相似文献
149.
150.
Tin(IV) complexes 1(a and b) and 2(a and b) of valine derived peptide derivatives were synthesized and characterized on the basis of elemental analysis, IR, 1H, 13C, 119Sn NMR, ESI-MS spectra and molar conductance measurements. The C-Sn-C angle was estimated from I3C and 1H NMR data 1J(119Sn, I3C) = 623 Hz; solution 2J(119Sn, 1H) = 93.04 Hz to be 149.9°. In vitro binding studies of complexes 1 and 2 under physiological conditions at room temperature with CT-DNA were carried out employing UV-visible, fluorescence, circular dichroism and viscometric studies. The binding affinity of the complexes was quantified by calculating the Kb values and it follows the order 2a > 1a > 2b > 1b. To further examine the specific mode of binding, the interaction of complexes 2(a and b) were carried out with 5′GMP and 5′TMP by using absorption and NMR (1H, 31P) spectroscopy. The supercoiled pBR322 plasmid DNA cleavage activity of the complexes was ascertained by gel electrophoresis assay. The complexes cleave supercoiled pBR322 plasmid DNA efficiently into its nicked form at micromolar concentrations. 相似文献