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991.
采用浸渍法制备了ZrO2-SiO2复合载体和Ni质量分数为6%的Ni/ZrO2-SiO2催化剂,考察了载体制备时浸渍溶液pH值、焙烧温度和催化剂制备时的焙烧温度对Ni/ZrO2-SiO2催化剂煤气甲烷化反应性能的影响。采用X射线衍射、程序升温还原和扫描电子显微镜等方法对催化剂进行了表征。结果表明,载体浸渍溶液pH值为8.0~9.0, 载体焙烧温度为550 ℃,催化剂焙烧温度为450 ℃时,Ni/ZrO2-SiO2催化剂在煤气甲烷化反应中显示了最优的催化性能,CO转化率100%,CO2转化率1.8%,CH4生成速率16.6 mmol/(h·g)。进一步表征发现,制备ZrO2-SiO2复合载体时,增大浸渍溶液的pH值有利于形成粒径较小的亚稳态四方晶相ZrO2,可见四方晶相ZrO2更有利于甲烷化反应;载体焙烧温度会影响到NiO粒径的大小和其在催化剂表面的分散,温度过高和过低都会导致NiO粒径大小的不适宜以及分散性的降低;催化剂焙烧温度过高则会导致NiO与载体间的相互作用减弱,NiO分散性降低。 相似文献
992.
This paper deals with the monitoring cyclo-addition of CO2 to methyl methacrylate(MMA)-glycidyl methacrylate (GMA) copolymers using spectral(1H-NMR and FTIR) and chemical(elemental analysis and titration) methods.Thus, poly(MMA-co-GMA),was first prepared via solution polymerization.The copolymer was then treated with CO2 gas flow in the presence of cetyltrimethyl ammoniumbromide as a catalyst.In terms of the carbonation reaction time,the terpolymer poly(MMA-co-GMA-co-2-oxo-l,3-dioxolane-4-yl-methyl methacrylate) was prepared in various yield of CO2 fixation (>90%).The peak intensity changes in the 1H-NMR and FTIR spectra provided excellent demonstrative techniques to monitor the carbonation reaction progression.In a comparative analytical viewpoint,the NMR and elemental analysis were recognized to be the most accurate ways to follow the cyclo-addition reaction progression.However,titration was recognized to be the most preferred method,because it is a very inexpensive,facile and available method with a reasonable costaccuracy balance. 相似文献
993.
Supercritical carbon dioxide(scCO2) was used as a reaction medium in synthesizing amphiphilic graft copolymers composed of poly(styrene-co-maleic anhydride)(SMA) backbones and methoxyl poly(ethylene glycol)(MPEG) side chains via esterification.The synthesized copolymers were characterized by Fourier transform infrared spectroscopy(FTIR),gel permeation chromatography(GPC),1H-NMR,thermo-gravimetric analysis(TGA) and differential scanning calorimetric analysis(DSC).The gelation phenomenon was suppressed effectively by tuning reaction conditions.The influences of scCO2 temperature and pressure on the conversion of anhydride were investigated.It was found that the highest conversion ratio occurred at 80℃under a constant pressure of 14 MPa or 26 MPa.With the increase of scCO2 pressure,the conversion ratio increased first,and then leveled off.The conversion ratio of anhydride could be controlled by regulating the reaction conditions.It was also revealed that using low molecular weight MPEG brought a high conversion ratio of anhydride. 相似文献
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997.
Damien Weidmann Chad B. Roller Clive Oppenheimer Alan Fried Frank K. Tittel 《Isotopes in environmental and health studies》2013,49(4):293-302
Recent developments of two mid-infrared tunable laser spectrometers dedicated to carbon isotope ratio determination are presented. First, a field deployable quantum cascade laser-based sensor is described, along with line selection strategy for 13/12CO2 ratio measurements. Secondly, an instrument architecture based on difference frequency generation is presented. The analyses of fundamental limitations, specifically temperature and pressure stability, and water vapor collision broadening, are detailed. 相似文献
998.
R. Russow R. Reinhardt H. Förstel H. Faust 《Isotopes in environmental and health studies》2013,49(1):59-66
Für die Untersuchung ausgewählter Probleme des Verhaltens und der Wirkung der Stickoxide NO x (NO + NO2) in Ökosystemen, z.B. die Aufnahme und Freisetzung von NOx durch das System “Boden-Pflanze”, bietet sich der Einsatz 15N-markierter Stickoxide an. Die dazu benötigten 15N-markierten Gasgemische hoher Reinheit werden aus eigens dafür synthetisiertem [15N]Stickstoffmonoxid oder [15N]Stickstoffdioxid mit hoher 15N-Häufigkeit hergestellt. Beide Synthesen gehen jeweils von der kostengünstig kommerziell erhältlichen [15N]Salpetersäure aus. Im Falle des [15N]Stickstoffdioxids erfolgt die Herstellung über die Präparation von Bleinitrat und dessen thermische Zersetzung. Die Ausbeute liegt bei 70–75% bezogen auf eingesetzte [15N]Salpetersäure. Die Herstellung von [15N]Stickstoffmonoxid erfolgt durch Reduktion von [15N]Salpetersäure mit Eisen-II-sulfat in stark saurer Lösung. Die Ausbeute beträgt 60–70%, bezogen auf eingesetzte Salpetersäure. The application of 15N is very useful for the investigation of the behavior and the effect of the nitrogen oxides NO x (nitric oxide + nitrogen dioxide) in ecosystems, e.g. the uptake and release of NO x by the soil-plant system. The 15N labelled gas mixture needed for that purpose has to be prepared from synthesized highly enriched [15N]nitric oxide and [15N]nitrogen dioxide. These two syntheses both use the commercially available and reasonable [15N]nitric acid. In the case of [15N]nitrogen dioxide the synthesis is carried out via [15N]lead nitrate and its decomposition with increasing temperature. The yield is 70–75% related to the [15N]nitric acid input. The preparation of [15N]nitric oxide is done by reduction of [15N]nitric acid by means of FeSO4 in strong acid solution. The yield amounts to 60–70%. 相似文献
999.
H.-M. Nitzsche W. Gläßer P. Harting 《Isotopes in environmental and health studies》2013,49(4):207-214
Abstract Gas analyses of the soil atmosphere of lignite mining dumps yielded increased contents of carbon dioxide. To get information about the potential sources and the carbon dioxide releasing capacity of the dumps, samples of dump material were investigated for their contents and isotopic compositions of organic and inorganic carbon as well as the carbon dioxide in the soil atmosphere. The contents of organic and inorganic carbon were found to vary depending on type of dump material. The isotopic composition of the organic carbon ranges between ?24.5 and ?26.5‰, which is typical for humous materials. The carbonates are found to be of marine origin (δ13C: +0.5 to ?1.1‰). By means of the isotope investigations it could be shown that the carbon dioxide in the lignite mining dump arises from these two different sources. Mixing ratios can be calculated using the isotope balance equation. Both reaction paths are associated with oxygen consumption and do not result in an increased gas pressure within the dump. 相似文献
1000.
Um zu prūfen, ob und unter welchen Bedingungen es möglich ist, den Fūllstand in Flüssiggaspatronen mittels Isotopenstrahlenschranken zu messen, wurden Röntgenaufnahmen bei verschiedenen Kapseltemperaturen gemacht. 相似文献