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排序方式: 共有425条查询结果,搜索用时 15 毫秒
61.
62.
K. C. Yung B. L. Zhu J. Wu T. M. Yue C. S. Xie 《Journal of Polymer Science.Polymer Physics》2007,45(13):1662-1674
Polymer matrix composites, based on brominated epoxy, a type of material widely used in printed circuit boards (PCBs), as matrix and AlN particle as filler were prepared. The influences of AlN content on the mechanical, thermal, and electrical properties of the composites were investigated by uniaxial tensile test, TMA, thermal conductivity measurement, DMA, and dielectric properties measurement. It was found that the properties of composites monotonically varied with AlN content except that maximum tensile strength and strain of composites corresponded to a filler content of 10 wt %. The results of DMA also showed the AlN reinforcement was more pronounced above Tg, and the peak area of tan δ versus T curves decreased with AlN content, which implied the damping capacity of the composite gradually decreased. The increase in Tg and decrease in damping were probably due to strong interaction between the AlN and epoxy matrix inhibiting the mobility of the epoxy chain. In addition, different theoretical models reported in the literature were used to predict the E, CTE, k, and Dk, and compared with the experimental data. Finally, suitable models were recommended in the present materials system. For the significant improvement of performance of epoxy, we can conclude that these composite materials may be promising for PCB substrate. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1662–1674, 2007 相似文献
63.
以氧化铕(Eu_2O_3)、对氯苯甲酸(PCBA)、对溴苯甲酸(PBrBA)和菲咯啉(phen)为原料制备了菲咯啉对氯苯甲酸铕[Eu(PCBA)_3phen]、菲咯啉对溴苯甲酸铕[Eu(PBrBA)_3phen]两种探针分子,并将这2种探针分子掺杂在甲基丙烯酸甲酯(MMA)中,以过氧化苯甲酰(BPO)为引发剂,制得Eu(PCBA)_3phen/PMMA和Eu(PBrBA)_3phen/PMMA温敏漆样品。利用红外光谱仪、扫描电子显微镜、紫外-可见分度光度计和荧光光谱仪对探针分子的组成结构、发光性能、形貌和温敏漆的温度敏感性进行了测试分析,研究了不同配体对探针分子发光性能和温敏漆性能的影响。结果表明,Eu~(3+)分别与对氯苯甲酸(PCBA)和对溴苯甲酸(PBrBA) 2种主配体配位,并且第二配体菲咯啉(phen)均参与了配位,成功合成了2种配合物。2种配合物均发出Eu~(3+)的特征荧光,其中以PBrBA为主配体的菲咯啉铕三元配合物具有更好的发光性能。此外,基于这2种探针分子制备的温敏漆在50~90℃范围内均具有温度猝灭性能,以Eu(PCBA)_3phen为探针制成的温敏漆温度敏感性更强。 相似文献
64.
通过硝酸镍与卤代希夫碱在甲醇溶液中反应,合成了2个Ni(Ⅱ)希夫碱配合物[Ni(3,5-Cl-salcy)](1)和[Ni(3-Cl-salcy)](2),(3,5-Cl-salcyH2=N,N′-(±)-双(3,5-二氯水杨基)-1,2-环己二胺; 3-Cl-salcyH2=N,N′-(±)-双(3-氯水杨基)-1,2-环己二胺)。通过X射线衍射测定了2个配合物的结构。结构分析表明2个配合物的基本单元均为Ni(Ⅱ)离子通过与希夫碱配体的[N2O2]原子配位构成相似的平面型单核配合物。Platon软件分析表明配合物1中并不存在任何氢键,配合物2也仅存在非经典氢键。通过Hirshfeld表面分析法对2个配合物晶体结构中弱交换作用的分析结果表明,虽然卤原子构成的氢键相对较弱,但是C-H…X在稳定三维超分子晶体结构中起着非常重要的作用;此外,通过2个配合物的对比发现,配体中卤原子数量的不同对于晶体中弱交换作用的占比可以起到非常重要的影响。 相似文献
65.
M. Sc. Steffen Mader Dr. Lise Molinari Dr. Matthias Rudolph Prof. Dr. A. Stephen K. Hashmi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(10):3910-3913
Various haloalkynes are converted in the presence of a dual activation gold catalyst. Via a dual activation process a completely atom economic head‐to‐tail coupling delivers gem‐dihalogenated conjugated enynes as valuable building blocks for organic synthesis. 相似文献
66.
《中国化学》2018,36(3):241-246
A new multi‐functional penta‐carbazole/benzophenone hybrid compound 5CzBP was designed and synthesized through a simple one‐step catalyst‐free C—N coupling reaction by using 2,3,4,5,6‐pentafluorobenzophenone and carbazole as starting materials. 5CzBP is very soluble in tetrahydrofuran (THF), which brings an environmentally friendly device fabrication for solution‐processed OLEDs instead of most widely used chlorinated solvents when 5CzBP is employed as the bulk‐phase of organic host or non‐doped emitter in the emissive layer. 5CzBP exhibits thermally activated delayed fluorescence (TADF) characteristic with relatively high triplet energy of 2.60 eV and a low ΔEST of 0.01 eV. By using the new TADF material as organic host for another green TADF emitter, maximum external quantum efficiency (EQE) of 12.5% has been achieved in simple solution‐processed OLED device. Besides, a maximum EQE of 8.9% and 5.7% was further obtained in TADF devices based on 5CzBP as dopant and non‐doped emitter, respectively. The simultaneously acting as efficient TADF host and non‐doped TADF emitter provides the potential guidance of the future simple single‐layer two‐color white OLEDs based on low‐cost pure organic TADF materials. 相似文献
67.
Alicja Kowalska Krystian Pluta Andrzej Masślankiewicz Roman Luboradzki 《Journal of chemical crystallography》1999,29(1):103-106
The title compound (C8H10N4O2) is monoclinic, with a = 7.740(2), b = 17.044(7), c = 6.992(3) Å, = 100.60(1)°, and space group P21/c. Two O-methyl groups are coplanar with the pyrimidine ring. Whereas, the O(6)-methyl group is directed away from the imidazole ring toward the N(1) atom, the O(2)-methyl is pointed away from the N(1) atom toward the N(3) atom. Two intermolecular hydrogen bonds H(8)···N(1) and H(711)···O(2) of 2.48(2) and 2.58(3) Å make a linear arrangement of the molecules. The conformation of the O-methyl groups explains some results of thermal rearrangement of 2,6-dialkoxy-7-methylpurines and differences in alkylations of 2,4-dialkoxypyrimidines and 2,6-dialkoxy-7-methylpurines. 相似文献
68.
Ian R. Pottie C. V. Krishnamohan Sharma Keith Vaughan Michael J. Zaworotko 《Journal of chemical crystallography》1998,28(1):5-10
The crystal and molecular structure of 1,2-bis-{1-(2-cyanophenyl)-3-methyltriazen-3-yl-}ethane (1) and 1,2-bis-{1-(2-methoxyphenyl)-3-methyltriazen-3-yl-}ethane (2) have been determined by single crystal X-ray diffraction analysis. Bis-triazene (1) exists as the staggered conformation in the solid state, with an anti-anti configuration around the N2–N3 bond of the triazene units, whereas 2 assumes a gauche conformation with the syn-syn configuration in the triazene units. Crystal data: 1 C18H18N8, triclinic, space group P –1, a = 6.108(2), b = 8.118(3), c = 9.600(4)Å, = 101.37(7)°, = 96.47(7)°, = 102.71(5)°, V = 449.1(3)Å3, Z = 2; 2 C18H24N6O2, monoclinic, space group P 21/n, a = 13.119(5), b = 7.745(2), c = 19.201(2)Å, = 96.47(7)°, V = 1910.3(9)Å3, Z = 4. 相似文献
69.
G. Madhurambal P. Ramasamy P. AnbuSrinivasan M. Suganthi G. Vasudevan S. C. Mojumdar 《Journal of Thermal Analysis and Calorimetry》2008,94(1):45-51
Good quality benzophenone (BP) crystals were grown by solution technique using CHCl3 as solvent by adopting slow evaporation method at room temperature. The grown crystals were subjected to various characterization
studies to analyze its purity and applications. The condensation product 2,4-dinitro phenyl hydrazone of benzophenone (DNPBP)
was prepared by adopting standard procedure. Then mixed crystal of BP and DNPBP was also grown by solution growth. Both the
condensation product and mixed crystals were characterized by UV, FTIR, 1H NMR spectra. Thermal (TG and DTA) studies have proved to be very useful techniques not only to study the thermal properties
of BP, DNPBP and mixed crystal but also to study their purity. Second harmonic generation (SHG) efficiency of the grown crystals
was determined. 相似文献
70.