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941.
J. J. Suñol J. Saurina F. Carrasco X. Colom F. Carrillo 《Journal of Thermal Analysis and Calorimetry》2007,87(1):41-44
Lyocell, modal and
viscose fibers were subjected to mercerization or to solar degradation. The
ulterior thermal degradation was analyzed by means of differential scanning
calorimetry (DSC). Thermal analysis shows wide exothermic processes that began
between 250 and 300°C corresponding to the main thermal degradation and
are associated to a depolymerization and decomposition of the regenerated
cellulose. Thermal degradation was analyzed as a function of concentration
and time. Lyocell fiber is the most stable under thermal degradation conditions.
Furthermore, mercerized samples are initially more degraded and present a
lower thermal stability. 相似文献
942.
G. Bonn H. Binder H. Leonhard O. Bobleter 《Monatshefte für Chemie / Chemical Monthly》1985,116(8-9):961-971
The alkaline degradation of cellobiose by 0.01 to 0.1N NaOH at temperatures between 60 and 85°C was studied. At the same time the formation of glucose and fructose was analyzed. At lower alkali concentrations, the production of acidic compounds lowered thepH to such an extent that the hydrolyzing reaction ceased within a relatively short time. At higher alkali concentrations thepH change is much smaller and first order reaction rates of the cellobiose degradation were obtained. Through the application of a simplified reaction mechanism the consecutive reactions of the glucose and fructose formation were evaluated mathematically.Dedicated to Prof. Dr.H. Tuppy on the occasion of his 60th birthday. 相似文献
943.
L. R. Grabowski E. M. van Veldhuizen A. J. M. Pemen W. R. Rutgers 《Plasma Chemistry and Plasma Processing》2006,26(1):3-17
A small batch reactor is developed to study the removal of phenol from a thin layer of water by creating pulsed corona discharges
above the water. Pulses of up to 40 kV are applied with a duration of ~50 ns and an energy of ~60 mJ. In this CAW (Corona
Above Water) reactor an ozone yield of upto 90 g/kWh is obtained in ambient air. The phenol degradation is 48 g/kWh, using
a 1 mM initial concentration in demineralized water. The degradation yield increases to almost 100 g/kWh by adding to the
water either H2O2 or Fe2SO4 or NaOH. The first two additions are considered to increase to amount of OH radicals. In the case of NaOH addition it is
observed that much more ozone dissolves in the water. The addition of the OH scavenger t-butanol shows that in most cases
the main oxidation route of phenol in the CAW reactor is direct ozone attack. 相似文献
944.
Pascal Charlier Robert Jrome Philippe Teyssi Robert E. Proud'Homme 《Journal of polymer science. Part A, Polymer chemistry》1993,31(1):129-134
The thermal stability of telechelic polystyrenes bearing quaternary ammonium iodide or ammonium sulfonate end groups is presented. It appears that the ammonium iodide functions are stable below 200°C. Above that temperature, the polystyrene irreversibly looses its functional end groups. The weight loss then observed leads to the conclusion that a Hofmann-type degradation mechanism is likely to take place. In contrast, the ammonium sulfonate-terminated polystyrene begins to degrade at 180°C and leads to a polymer which is no longer end-capped with sulfonic acid or sulfonate groups. This behavior is of importance, especially for the study of multiblock ionic copolymers which are prepared by blending two telechelic polymers, one of them bearing sulfonic acid end groups and the other one tertiary amine functional groups. © 1993 John Wiley & Sons, Inc. 相似文献
945.
Abate L: Blanco A: Pollicino A. Recca A. 《Journal of Thermal Analysis and Calorimetry》2002,70(1):63-73
The isothermal degradation of three aromatic polyetherketones was studied in an inert environment at various temperatures
in the range 683-803 K. In the first degradation stage (mass loss D£20%) a linear increase of D as a function of heating time (t) was observed and the corresponding kinetic D=D
o+bt equations at various temperatures were directly drawn by smoothing the experimental TG data. The b values, which represent
the mass loss rates during degradation, increased as a function of temperature according to Arrhenius-type equations, from
which degradation E
a values were determined, which appear in agreement with those from literature methods. Some differences observed were discussed
and interpreted.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
946.
Oxo-biodegradable carbon backbone polymers - Oxidative degradation of polyethylene under accelerated test conditions 总被引:2,自引:0,他引:2
Oxo-biodegradation of carbon-only backbone polymers is receiving ever increasing attention for the practical implications that some re-engineered thermoplastic polymer formulations based on conventional biostable polymeric materials may satisfy in terms of environmental friendliness and acceptance by commodity plastic manufacturers.In this respect, as part of our continuing activity in the area of bioactive polymeric materials for biomedical and environmental applications, we report the results of an investigation of the effects of different degradation conditions on the oxidative degradation of polyethylene (PE) film samples containing pro-oxidant additives and formulated according to a proprietary technology. The effects of temperature and relative humidity have been evaluated by monitoring, with time, several parameters associated to oxidation and cleavage of the macromolecules, such as the weight variation due to oxygen uptake, film wettability, carbonyl index, molecular weight and the extractability with polar solvents of oxidized PE samples. 相似文献
947.
Araujo E Rodríguez-Malave AJ González AM Rojas OJ Peñaloza N Bullón J Lara MA Dmitrieva N 《Applied biochemistry and biotechnology》2002,97(2):91-103
In this work, the effect of Fento’s reagent on the degradation of residual Kraft black liquor was investigated. The effect
of Fenton’s reagent on the black liquor degradation was dependent on the concentration of H2O2. At low concentrations (5 and 15 mM) of H2O2, Fenton’s reagent caused the degradation of phenolic groups (6.8 and 44.8%, respectively), the reduction of reaction medium
pH (18.2%), and the polymerization of black liquor lignin. At a high concentration (60 mM) of H2O2, Fenton’s reagent induced an extensive degradation of lignin (95–100%) and discoloration of the black liquor. In the presence
of traces of iron, the addition of H2O2 alone induced mainly lignin fragmentation. In conclusion, Fenton’s reagent and H2O2 alone can degrade residual Kraft black liquor under acidic conditions at room temperature. 相似文献
948.
掺杂过渡金属离子的TiO2复合纳米粒子光催化剂──罗丹明B的光催化降解 总被引:64,自引:0,他引:64
在悬浮液体系中进行的半导体光催化降解反应中,催化剂的导带电子(或被俘获到半导体表面的电子)还原电解质溶液的O2分子(受主)是反应的决速步骤,O2分子接受电子后形成的超氧自由基O2-或羟基自由基HO·具有很强的氧化能力,能将污梁物氧化降解[13]. 相似文献
949.
采用阴极电沉积和阳极氧化法制备了Fe2O3改性TiO2纳米管(Fe2O3/TiO2-NTs)电极,运用场发射扫描电子显微镜、透射电子显微镜、X射线衍射和紫外-可见漫反射光谱等手段对其进行了表征,考察了其光电化学性能,并研究了复合电极光电催化降解甲基橙染料废水的反应性能.结果表明,Fe2O3的负载成功地将TiO2-NTs的光响应区间拓宽到可见光区域,Fe2O3/TiO2-NTs复合电极的光电流密度达到TiO2-NTs电极的3倍.在光电催化反应中,Fe2O3/TiO2-NTs复合电极对甲基橙的脱色效果明显优于TiO2-NTs电极,以Fe2O3/TiO2-NTs为阳极,光照5min,甲基橙溶液的脱色率可达90%以上. 相似文献
950.
本文首先制备了与AlGaN/GaN高电子迁移率晶体管 (HEMT) 结构与特性等效的AlGaN/GaN异质结肖特基二极管, 采用步进应力测试比较了不同栅压下器件漏电流的变化情况, 然后基于电流-电压和电容-电压测试验证了退化前后漏电流的传输机理, 并使用失效分析技术光发射显微镜 (EMMI) 观测器件表面的光发射, 研究了漏电流的时间依赖退化机理. 实验结果表明: 在栅压高于某临界值后, 器件漏电流随时间开始增加, 同时伴有较大的噪声. 将极化电场引入电流与电场的依赖关系后, 器件退化前后的 log(IFT/E)与√E 都遵循良好的线性关系, 表明漏电流均由电子Frenkel-Poole (FP) 发射主导. 退化后 log(IFT/E)与√E 曲线斜率的减小, 以及利用EMMI在栅边缘直接观察到了与缺陷存在对应关系的“热点”, 证明了漏电流退化的机理是: 高电场在AlGaN层中诱发了新的缺陷, 而缺陷密度的增加导致了FP发射电流IFT的增加.
关键词:
AlGaN/GaN
高电子迁移率晶体管
漏电流
退化机理 相似文献