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991.
The dense-structured zeolites of types ZSM-5 (MFI) and mordenite (MOR) of different SiO2/Al2O3 moduli are relatively stable under treatment by liquid water for 72 hours up to 513 K. The open-structured zeolites of types
Y in dealuminated modification (FAU) and beta (BEA) undergo strong decomposition in the same range. For these two sample types
a mathematical model for the decomposition of the zeolite framework is established that takes into account the influence of
modulus as well as temperature. Here the kinetic of the solid phase reaction is a superposition of two different mechanisms
described by the Monod equation.
Dedicated to the late of Wolfgang Schirmer. 相似文献
992.
993.
J. F. Brilhac B. Pateyron J. F. Coudert P. Fauchais A. Bouvier 《Plasma Chemistry and Plasma Processing》1995,15(2):257-277
This work was devoted to the study of the dynamic and static behavior of de vortex plasma torch with a well-type cathode (power level below 100 kW). The dynamic behavior of the torch was characterized by the fulctuations of arc voltage and current, plasma jet radiation, and acoustic pressure. Characteristic frequencies of the arc root movement inside the torch were observed. By numerical simulation (with the numerical codeMelodie, it was shown that the position of the erosion diameter) of the axial velocity along the cathode channel near the wall. The static behavior of the torch was inverstigated for different cathode designs. The variations of voltage U with arc current I, gas flow rate G nature of the gas and cathode design were represented by semiempirical relationships established between dimensionless numbers. By dimensional analysis, the behavior of this torch was compared with that of two powerful torches: the Aerospatiale and the Plasma Energy Corporation torches. 相似文献
994.
In situ
developments of platelike spodumene–diopside grains were obtained by
controlled devitrification of the complex system Li2O–CaO–MgO–Al2O3–SiO2 glass. The crystallization mechanisms
of spodumene–diopside glass were measured by isothermal and non-isothermal
processes using classical and differential thermal analysis techniques. The
Avrami constant n was 2.0–2.1, indicating
two-dimensional crystal growth and platelike grains. The crystalline phases
precipitated first were high-quartzs.s., then transformed
to β-spodumene and diopside. The Flexural strength, fracture toughness
and thermal shock resistance (in 20°C water) increased from 145 MPa, 1.3
MPa m1/2, 800°C (pure spodumene) to 197 MPa,
2.9 MPa m1/2 and 920°C (spodumene–diopside)
with low thermal expansion coefficient (from 3∼9·10–7
to 11.8·10–7 K–1).
This mean in situ developments of platelike spodumene–diopside grains
reinforced the low thermal expansion coefficient glass-ceramics. 相似文献
995.
To enhance film conformality together with electrical property suitable for dynamic random access memory (DRAM) capacitor
dielectric, the effects of oxidant and post heat treatment were investigated on aluminum and titanium oxide (Al2O3–TiO2) bilayer (ATO) thin film formed by atomic layer deposition method. For the conformal deposition of Al2O3 thin film, the O3 oxidant required a higher deposition temperature, more than 450 °C, while H2O or combined oxygen sources (H2O+O3) needed a wide range of deposition temperatures ranging from 250 to 450 °C. Conformal deposition of the TiO2 thin film was achieved at around 325 °C regardless of the oxidants. The charge storage capacitance, measured from the ATO
bilayer (4 nm Al2O3 and 2 nm TiO2) deposited at 450 °C for Al2O3 and 325 °C for TiO2 with O3 oxidant on the phosphine-doped poly silicon trench, showed about 15% higher value than that of 5 nm Al2O3 single layer thin film without any increase of leakage current. To maintain the improved electrical property of the ATO bilayer
for DRAM application, such as enhanced charge capacitance without increase of leakage current, upper electrode materials and
post heat treatments after electrode formation must be selected carefully.
Dedicated to Professor Su-Il Pyun on the occasion of his 65th birthday. 相似文献
996.
A method was developed for the generation of mercury vapour by means of cold-vapour flow-injection atomic absorption spectrometry (FI-CV-AAS) from white wine samples after ozonation as sample pre-treatment. Two different reactors designs for sample ozonation were developed and investigated. The limit of detection and the limit of quantification were, respectively, 0.5 and 1.7 μg l−1, and the relative standard deviation (n=10) was 2% for a concentration of 50 μg l−1 and 7% for a concentration of 5 μg l−1. The pre-treatment with ozone has allowed to reduce drastically the amount of chemical reagents (e.g. carrier agent and reducing agent) used in the FI-CV-AAS system. The mercury content of wine samples was also determined by FI-CV-AAS after pre-concentration in the presence of HNO3 and H2O2. In general, there was no significant difference among data obtained from both methodologies, but pre-treatment with ozone is much faster. 相似文献
997.
T. Kaljuvee M. Radin D. Astahhov Y. Pelovski 《Journal of Thermal Analysis and Calorimetry》2006,84(1):59-66
Coupled
TG-FTIR technique was used for identification of gaseous compounds evolved
at thermal treatment of six coal samples from different deposits (Bulgaria,
Russia, Ukraine). The experiments were carried out under dynamic heating conditions
up to 900°C at heating rates of 5, 10 or 50 K min–1
in a stream of dry air. The emission of CO2, H2O,
CO, SO2, COS, methane, methanol, formic acid, formaldehyde,
acetaldehyde, chlorobenzene was clearly identified in FTIR spectra of the
samples studied. The formation of ethanol, ethane, ethylene and p-xylene, at least on the level of traces, was also
identified. At the heating rate of 5°C min–1
the temperature of maximum intensities of the characteristic peaks of COS
was 270°C, of formaldehyde, formic acid, ethane and methanol 330°C,
of SO2, CO, acetic acid, ethylene and p-xylene
400°C and of chlorobenzene 500°C. At 10°C min–1
and 50°C min–1 these temperatures were
shifted, respectively, by 70–300°C and 150–450°C towards
higher temperatures and the respective absorption bands in FTIR spectra were,
as a rule, more intensive. 相似文献
998.
A white rot fungus species Lentinus sajor-caju biomass was entrapped into alginate gel via a liquid curing method in the presence of Ca(II) ions. The biosorption of cadmium(II) by the entrapped live and dead fungal biomass has been studied in a batch system. The heat-treatment process enhanced the biosorption capacity of the immobilized fungal biomass. The effect of initial cadmium concentration, pH and temperature on cadmium removal has been investigated. The maximum experimental biosorption capacities for entrapped live and dead fungal mycelia of L. sajur-caju were found to be 104.8±2.7 mg Cd(II) g−1 and 123.5±4.3 mg Cd(II) g−1, respectively. The kinetics of cadmium biosorption was fast, approximately 85% of biosorption taking place within 30 min. The biosorption equilibrium was well described by Langmuir and Freundlich adsorption isotherms. The change in the biosorption capacity with time is found to fit pseudo-second-order equations. Cadmium binding properties of entrapped fungal preparations have been determined applying the Ruzic equations. Since the biosorption capacities are relatively high for both entrapped live and dead forms, they could be considered as suitable biosorbents for the removal of cadmium in wastewater treatment systems. The biosorbents were reused in three consecutive adsorption/desorption cycles without significant loss in the biosorption capacity. 相似文献
999.
E. Kowalska J. Radomska P. Konarski R. Diduszko J. Oszczudłowski T. Opalińska M. Więch Z. Duszyc 《Journal of Thermal Analysis and Calorimetry》2006,86(1):137-140
Two components
of electronic wastes (sample A – a mixture of three types of printed
circuit boards, sample B – a mixture of electronic junctions with metal
wires) were investigated using thermogravimetric analysis (TG). Thermogravimetric
and derivative thermogravimetric data (TG and DTG) give information on the
thermal stability of A and B samples and allows finding the correct conditions
for their degradation using pyrolysis in an experimental system, built on
the laboratory scale for utilization of hazardous wastes. X-ray fluorescence
measurements prove that brominated flame retardant is present in sample A,
whilst chlorinated flame retardant is a probable component of sample B. Preliminary
liquid chromatography of oil products obtained as a result of thermal waste
degradation shows that the hydrocarbons released during pyrolysis could be
used as a fuel. 相似文献
1000.
等离子体改性聚丙烯纤维表面的XPS研究 总被引:12,自引:0,他引:12
用等离子体技术处理了聚丙烯纤维表面.用X-射线光电子能谱(XPS)研究了聚合物表面的元素组成、相对含量的变化、表面官能团的类型.采用曲线拟合分峰技术对谱图进行数学处理,结果表明:尽管处理气氛不同,聚丙烯纤维表面除含有C—H和C=C键外,还引入了O、N元素.形成活性基团:-OH、>C=O、-COOH、-NH2和-CONH2等,提高了聚合物表面活性。 相似文献