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991.
磁场对重电子金属CeCu6-xNix低温电阻的影响   总被引:1,自引:0,他引:1  
测量了重电子金属CeCu6-xNix(x=0,0.5,0.1),在1.8k-300k温度范围的电阻及磁场对电阻的影响(H=0,5T,10T),实验表明样品电阻的极大值对应的温度Tmax随着掺Ni含量的增大向温度降低的方向移动,而加磁场后Tmax随磁场的增加向高温方向移动,中从Kondo相互作用和相干散射的角度对这一现象的物理机制进行了分析.  相似文献   
992.
合成并用红外光谱法、核磁共振法和高效凝胶渗透色谱法表征了胆甾(烷)醇十一碳烯酸酯分别与庚烯 1、二氧化硫进行自由基共聚合得到的一系列不同组成的三元胆甾型侧链液晶共聚砜,用温控式偏振光显微镜观测了产物的液晶性能.结果表明:随庚烯 1单体单元组份含量的增加,该三元共聚砜的液晶相转变温度均降低,采用庚烯 1单体参与共聚的方法可以有效地调节胆甾型侧链液晶共聚砜的热转变温度.  相似文献   
993.
水喷射淬冷高温壁面的传热实验研究   总被引:9,自引:1,他引:8  
本文采用直接表面温度测量的方法对水喷射高温壁面的传热过程进行实验研究.系统地研究了射流出口速度、冷却水过冷度、喷嘴至加热面的间距、初始壁温以及水喷雾的流量密度等参数对淬冷表面的膜态沸腾、最小临界点、过渡沸腾、最大临界点等传热过程的影响,给出了有关实验结果,分析了它们的特点。  相似文献   
994.
Joseph H. Flynn   《Thermochimica Acta》1997,300(1-2):83-92
This paper first reviews the history of the temperature dependence of reaction rate in reaction kinetics. The various equations which are in use today for expressing this dependence were delineated by van't Hoff almost one hundred years ago. Since an exponential form best describes this dependence for most thermal analysis reactions and, due to the fact that the simple Arrhenius equation (with a temperature-independent preexponential factor) has traditionally been used for this purpose, the mathematically intractable temperature integral often has become a necessary evil in the analysis of thermal analysis kinetics. Methods which avoid the temperature integral in kinetics analysis are discussed. The merits of various evaluations and approximations for the temperature integral are described and assessed in this paper.  相似文献   
995.
Two novel poly(amine‐hydrazide)s were prepared from the polycondensation reactions of the dicarboxylic acid, 9‐[N,N‐di(4‐carboxyphenyl)amino]anthracene ( 1 ), with terephthalic dihydrazide ( TPH ) and isophthalic dihydrazide ( IPH ) via the Yamazaki phosphorylation reaction, respectively. The poly(amine‐hydrazide)s were readily soluble in many common organic solvents and could be solution cast into transparent films. Differential scanning calorimetry (DSC) indicated that these hydrazide polymers had glass‐transition temperatures (Tg) in the range of 182–230 °C and could be thermally cyclodehydrated into the corresponding oxadiazole polymers in the range of 300–400 °C. The resulting poly(amine‐1,3,4‐oxadiazole)s had useful levels of thermal stability associated with high Tg (263–318 °C), 10% weight‐loss temperatures in excess of 500 °C, and char yield at 800 °C in nitrogen higher than 55%. These organo‐soluble anthrylamine‐based poly(amine‐hydrazide)s and poly (amine‐1,3,4‐oxadiazole)s exhibited maximum UV‐vis absorption at 346–349 and 379–388 nm in N‐methyl‐2‐pyrrolidone (NMP) solution, respectively. Their photoluminescence spectra in NMP solution showed maximum bands around 490–497 nm in the green region. The poly(amine‐hydrazide) I ‐ IPH showed a green photoluminescence at 490 nm with PL quantum yield of 29.9% and 17.0% in NMP solution and film state, respectively. The anthrylamine‐based poly(amine‐1,3,4‐oxadiazole)s revealed a electrochromic characteristics with changing color from the pale yellow neutral form to the red reduced form when scanning potentials negatively from 0.00 to ?2.20 V. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1584–1594, 2009  相似文献   
996.
Poly(thianthrene phenylene sulfide) and poly(thianthrene sulfide) have been prepared by nucleophilic aromatic substitution polymerization of the activated monomer 2,7‐difluorothianthrene with bis thiophenoxide and sulfide nucleophiles, respectively. The resulting polymers are thermally stable, amorphous materials that have been characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), gel permeation chromatography (GPC), matrix‐assisted laser desorption/ionization‐time‐of‐flight (MALDI‐TOF) mass spectrometry, UV‐Vis spectroscopy, refractometry, and intrinsic viscosity (IV) measurements. The polymers produced exhibit 5% weight loss values approaching 500 °C in inert and air atmospheres and glass transition temperatures that range from 149 to 210 °C. Poly(thianthrene phenylene sulfide) with a number average molecular weight of 22,100 g/mol has been synthesized with an IV in DMPU of 0.62 dL/g at 30 °C. Creasable films of this polymer have been prepared by solvent casting and melt pressing at 250 °C. Films of poly(thianthrene phenylene sulfide) exhibit transparencies greater than 50% at wavelengths exceeding 400 nm and a high refractive index value of 1.692 at a wavelength of 633 nm, making the polymer interesting for optical applications. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2453–2461, 2009  相似文献   
997.
A novel phosphorus‐containing thermotropic liquid crystalline copolyester with flexible spacers (P‐TLCP‐FS) was synthesized by melt transesterification from p‐acetoxybenzoic acid (p‐ABA), terephthalic acid (TPA), ethylene glycol, and acetylated 2‐(6‐oxid‐6H‐dibenz(c,e) (1,2) oxaphosphorin 6‐yl) 1,4‐benzenediol (AODOPB). The chemical structure and properties of the obtained P‐TLCP‐FS were characterized by Fourier‐transform infrared spectroscopy (FT‐IR), proton nuclear magnetic resonance spectroscopy (1H‐NMR), inherent viscosity measurements, differential scanning calorimetry (DSC), thermogravimetry (TGA), polarizing light microscopy (PLM), and X‐ray diffraction (XRD) analysis. P‐TLCP‐FS had inherent viscosities of 0.92–1.12 dL/g and exhibited low and wide mesophase temperatures, ranging from 185 to 330 °C, which can match with the processing temperatures of most conventional polymers and high flame retardancy with a limiting oxygen index value of 70% and UL‐94 V‐0 rating. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5752–5759, 2008  相似文献   
998.
煤燃烧过程中汞、砷、硒反应机理研究   总被引:6,自引:0,他引:6  
本文以三种典型煤为对象,测定了煤及灰中汞,砷,硒的浓度,了解了元素的挥发性。对钱家营褐煤进行了不同温度的燃烧实验。测定了在不同温度下燃烧灰中汞,砷,硒的含量变化。将所得实验结果与化学热力平衡分析工具F~*A~*C~*T2.1模拟系统结果相比较。推测了其中可能发生的反应。  相似文献   
999.
The voltammetric response of graphite or carbon nanotube paste electrodes, which incorporate the room temperature ionic liquid, N‐butyl‐N‐methyl pyrrolidinium bis(trifluoromethylsulfonyl) imide or [C4mpyrr][NTf2], (RTIL‐CNTPE and RTIL‐CPE respectively) as the binder, towards anionic, cationic and neutral redox probes is examined and compared to conventional paste electrodes which use mineral oil as the binder. The RTIL paste electrodes are found to suffer from very large background currents due to capacitive charging. This is exacerbated further when CNTs are combined with RTILs in the paste. The large charging currents obscure any Faradaic processes of interest, especially at low analyte concentrations. By employing steady state voltammetry at a rotating disk electrode made of the RTIL pastes this problem can be overcome. This allows the electroanalytical properties of these interesting electrode substrates, which combine the attractive properties of CNTs with RTILs to be further explored and developed.  相似文献   
1000.
通过对柚子型微结构光纤Bragg光栅的多个反射峰的温度和应变传感特性进行的理论和实验 研究,得出柚子型微结构光纤Bragg光栅的反射波长与温度呈二次关系,且理论和实验二者 吻合较好; 同时发现每个反射峰的温度灵敏度不同.理论分析柚子型微结构光纤Bragg光栅的 反射波长与应变呈线性关系,实验得到了该种Bragg光栅的反射波长与应变的线性关系,实 验结果与理论分析相吻合.由于微结构光纤光栅反射谱中多个峰对温度和应变等物理量敏感 度不一致,这种Bragg光栅更适合应用到多参量传感领域. 关键词: 微结构光纤 光纤Bragg光栅 温度传感 应变传感  相似文献   
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