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161.
Diana I. Martin Elena Mateescu Gabriela Craciun Daniel Ighigeanu Adelina Ighigeanu 《Radiation Physics and Chemistry》2002,64(5-6):423-428
Results obtained by accelerated electron beam, microwave and simultaneous microwave and electron beam application in the chemistry of acrylamide and acrylic acid copolymers (polymeric flocculants used for wastewater treatment) are presented. Comparative results concerning the molecular weight and Huggins’ constant for the acrylamide and acrylic acid copolymers obtained by classical heating, microwave heating, electron beam irradiation and simultaneous microwave and electron beam treatment are reported. Microwave heating produces high water solubility of the polymeric flocculants but median molecular weight values. Electron beam irradiation gives high molecular weight values but associated with a cross-linked structure (poor water solubility) while microwave energy addition to electron beam energy gives simultaneously high molecular weight values and high water solubility. 相似文献
162.
A. Castaeda Facio R. Benavides M.E. Martínez Pardo R. Uribe 《Radiation Physics and Chemistry》2007,76(11-12):1720-1723
PVC samples with lead-free and lead-base stabilizer, containing TMPTMA (trimethylolpropane trimethacrylate) as a crosslinker and DOP (2-ethylhexyl phthalate) as a plasticizer, were electron beam treated at different doses (2–200 kGy) and characterized to evaluate crosslinking and other several properties, as a continuation of our previously reported paper, where these PVC formulations, typical for wire and cable applications, underwent gamma irradiation. The PVC was formulated with two different stabilizing systems: Ca/Zn and dibasic lead phthalate for comparison, to use them as jackets for a 22 wire gage (AWG). Small samples of the jacketed wires were irradiated in an industrial Dynamitron electron accelerator for the corresponding doses, along with two dosimetric systems: radiochromic thin film and alanine pellets dosimeters. The maximum dose applied was decided as the crosslinking increased, until the gel content was stable. The dose of 200 kGy was the condition for the highest crosslinking, so most of the wire was irradiated at such dose. Chemical and mechanical evaluations were carried out to the irradiated wire. The results show that 200 kGy was too high dose for the materials, since an important degradation is observed for the Ca/Zn systems. Unfortunately, such dose affects basically to CaZn formulations, which showed much poorer performance than classical lead-containing compositions. The results also indicate that gel content is not the best way of deciding the optimum condition for irradiation. 相似文献
163.
ZHANG Shu-dong KONG Xiang-he ZHU Xiang-jun WANG Yan JIANG Su-rong 《高等学校化学研究》2006,22(5):621-625
IntroductionReactions of metal ions with neutral molecules orclusters produce a variety of metal complex ions andother new series of cluster ions including cations andanions.The laser ablation-molecular beam(LA-MB)method has marked its relevance in the st… 相似文献
164.
As a new concept for the design of effective photocatalysts, an ion beam technology using accelerated metal ions, a metal ion implantation and an ionized cluster beam (ICB) method, have been applied to design unique photocatalysts. The metal ion implantation of TiO2 and Ti-containing zeolites with highly accelerated metal ions (V+, Cr+, etc.) is useful in designing photocatalysts that can operate efficiently under visible light irradiation. Also, an ICB method with a low acceleration energy is useful in preparing transparent TiO2 thin films on various types of substrates for the efficient photocatalytic degradation of pollutants diluted in water and air. The combination of the ICB method and metal ion implantation can develop the TiO2 thin films that are able to operate not only under UV light but also under visible light irradiation. 相似文献
165.
V.L. Auslender I.V. Gornakov V.M. Radchenko E. Shtarklev V.O. Tkachenko L.A. Voronin 《Radiation Physics and Chemistry》2007,76(11-12):1792-1794
The report describes electron beam electromagnetic forming system, which is destined for irradiation of cylindrical long goods, specifically for PE tubes 160 mm diameter. System consists of electromagnet, power supply units, beam distributions control units, etc. for use at an electron accelerator at 5 MeV and 50 kW. The particular geometry of the magnet poles and their mutual arrangement are creating an irradiation field that allows the electrons to irradiate the surface of the product close to 90°. 相似文献
166.
报道用催化反应热诱导激光光偏转法测定痕量尿素。发现将脲酶制成一定浓度的乙醇浓液能显著地增强激光光偏转信号强度。探讨了增强作用机理以及光偏转号强度与尿素浓度的关系,并应用于尿样中尿素含量的测定,结果满意。 相似文献
167.
James O. Alben Allan A. Croteau Frank G. Fiamingo Craig F. Hemann Virginia A. Molleran Sungjo Park Kimerly A. Powell 《Mikrochimica acta》1988,94(1-6):335-338
Biological applications of infrared spectroscopy have pressed for ever greater instrumental capabilities in terms of spectral sensitivity and quantitative exactness. Improved instrumentation has provided measurement of many vibrational modes in biological samples that previously were lost in noise. With highly optimized sampling conditions, useful measurements have been made with a peak-to-peak noise level less than 5 microabsorbance (5×10–6 absorbance), at 0.5 cm–1 resolution. However, optical and instrumental instabilities often result in sine waves that are not totally removed by the ratio of sample to reference. These often limit effective spectral sensitivity to 50 or 100 microabsorbance, peak-to-peak, and constitute a non-random noise. Non-atmospheric absorptions, especially one at 1959 cm–1 with 0.8 cm–1 band width (FWHM) are reported. The latter is due to a trace impurity in the KBr beam splitter substrate and compensator plate. Improvements in instrumentation and sampling conditions are expected to yield measurements of absorption bands as small as 50 microabsorbance with excellent signal/noise. 相似文献
168.
A piezoelectric method is proposed for the determination of sulfite in concentration range 1 × 10–7–1 × 10–5 mol/1. The method is based on the redox reaction of sulfite with iodine followed by measuring frequency change of the piezoelectric crystal caused by the unreacted iodine. The method is applied to the determination of sulfite in liquor. 相似文献
169.
The pretreatment of waste-activated sludge (WAS) by electron beam irradiation was studied in order to improve anaerobic sludge
digestion. The irradiation dose of the electron beam was varied from 0.5 to 10 kGy. Batch and continuous-flow stirred tank
reactors (CFSTRs) were operated to evaluate the effect of the electron beam pretreatment on anaerobic sludge digestion. Approximately
30–52% of the total chemical oxygen demand (COD) content of the WAS was solubilized within 24 h after electron beam irradiation.
A large quantity of soluble COD, protein, and carbohydrates leached out from cell ruptures caused by the electron beam irradiation.
Volatile fatty acids production from the irradiated sludge was approx 90% higher than that of the unirradiated sludge. The
degradation of irradiated sewage sludge was described by two distinct first-order decay rates (k
1 and k
2). Most initial decay reaction accelerated within 10 d, with an average k
1 of 0.06/d for sewage sludge irradiated at all dosages. The mean values for the long-term batch first-order decay coefficient
(k
2) were 0.025/d for irradiated sewage sludge and 0.007/d for unirradiated sludge. Volatile solids removal efficiency of the
control reactor fed with unirradiated sewage sludge at a hydraulic retention time (HRT) of 20 d was almost the same as that
of the CFSTRs fed with irradiated sludge at an HRT of 10 d. Therefore, disintegration of sewage sludge cells using electron
beam pretreatment could reduce the reactor solid retention time by half. 相似文献
170.
Nitrogen ion implantation (24 keV, 4.6 × 1017 cm?2) into (100) a p‐type silicon wafer material and a subsequent electron beam annealing at 1100 °C for 15 s under high vacuum conditions leads to the formation of an uneven surface in the implanted region caused by nitrogen bubbles beneath the surface. Annealing at 1200 °C for 300 s results in surface cavities with a mean diameter of 350 nm and a surface coverage of 3–4% and an average depth of ~60 nm. Nuclear reaction analysis reveals that the nitrogen concentration in the as‐implanted state exceeds 57 at%, the value of stoichiometric Si3N4. Annealing at 1100 °C for 15 s slightly reduces the nitrogen peak concentration, whereas annealing at 1200 °C for 300 s induces a significant alteration to the shape of the nitrogen depth profile coupled with the lowering of the concentration close to the stoichiometry of Si3N4. The results present a new method of producing sub‐micrometre cavities embedded in a thin silicon nitride film on wafer silicon which may lead to novel micro‐electronic and biotechnology applications. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献