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31.
32.
通过熔盐法制备TiB2载体,并采用简单的沉淀-沉积法制备了Co/TiB2磁性可回收纳米催化剂,用于室温催化氨硼烷(NH3BH3)溶液产氢及串联降解对硝基苯酚(4-NP)及偶氮染料酸性橙7(AO7)、酸性红1(AR1)和甲基橙(MO)等有机污染物。采用X射线衍射、扫描电子显微镜、透射电子显微镜、X射线光电子能谱、振动样品磁强计等表征方法对催化剂的微观形貌和结构等进行分析。结果表明,Co纳米粒子均匀地分布在TiB2载体表面,晶粒尺寸约为40 nm,并且被TiB2载体包覆,具有典型的金属-载体强相互作用。Co/TiB2表现出优异的室温催化NH3BH3溶液产氢活性,产氢速率为565.8 molH2·molcat-1·h-1。在串联降解有机污染物反应中,Co/TiB2在7 min内催化4-NP氨基化的转化率接近100%,反应速率常数高达0.72 min-1;降解AO7的反应速率常数在3种偶氮染料中最高(0.34 min-1)。通过EPR-DMPO(EPR=电子顺磁共振,DMPO=5,5-二甲基-1-吡咯啉-N-氧化物)自由基捕获实验检测出Co/TiB2+NH3BH3催化体系中产生大量的氢自由基(·H)。得益于·H的强还原性,Co/TiB2+NH3BH3催化体系能够将4-NP氨基化为具有更高价值的对氨基苯酚(4-AP),同时能够还原偶氮染料分子中的显色基团偶氮基(—N=N—)。 相似文献
33.
Two cyano-bridged dimetallic complexes derived from MnIII(Schiff-base) and [CrI(CN)5NO]3−, [Mn(3-CH3)salen]3[Cr(CN)5NO]·2.5H2O (1) and [Mn(5-CH3)salen]6[Cr(CN)5NO]2·2CH3OH·16H2O (2) [salen = N,N′-ethylenebis (salicylideneiminato)dianion] were synthesized and characterized. The reaction conditions of the two complexes are identical. The substituting group (CH3-) in the salen-type ligands gives different assembly styles for the two complexes, 1D zigzag chain for 1 while 2D grid network for 2. The magnetic investigation indicates the dominant antiferromagnetic interactions between the Mn(III) and Cr(I) mediated by the CN bridge. Due to the weak interchain antiferromagnetic interactions, no magnetic ordering phase was observed in complex 1. Interestingly, complex 2 showed the long range ferrimagnetic magnetic ordering with Tc = 9 K, in contrast to 1. Furthermore, the hysteresis loop confirms the nature of complex 2 as soft ferrimagnet. 相似文献
34.
Wang C Yan Q Liu HB Zhou XH Xiao SJ 《Langmuir : the ACS journal of surfaces and colloids》2011,27(19):12058-12068
Infrared spectroscopy was applied to investigate the well-known EDC/NHS (N-ethyl-N'-(3-(dimethylamino)propyl)carbodiimide/N-hydroxysuccinimide) activation details of poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA) brushes grafted on porous silicon. Succinimidyl ester (NHS-ester) is generally believed to be the dominant intermediate product, conveniently used to immobilize biomolecules containing free primary amino groups via amide linkage. To our surprise, the infrared spectral details revealed that the EDC/NHS activation of PMAA generated anhydride (estimated at around 76% yield and 70% composition), but not NHS-ester (around 5% yield and 11% composition) under the well-documented reaction conditions, as the predominant intermediate product. In contrast, EDC/NHS activation of PAA still follows the general rule, i.e., the expected NHS-ester is the dominant intermediate product (around 45% yield and 57% composition), anhydride the side product (40% yield and 28% composition), under the optimum reaction conditions. The following amidation on PAA-based NHS-esters with a model amine-containing compound, L-leucine methyl ester, generated approximately 70% amides and 30% carboxylates. In contrast, amidation of PAA- or PMAA-based anhydrides with L-leucine methyl ester only produced less than 30% amides but more than 70% carboxylates. The above reaction yields and percentage compositions were estimated by fitting the carbonyl stretching region with 5 possible species, NHS-ester, anhydride, N-acylurea, unreacted acid, unhydrolyzed tert-butyl ester, and using the Beer-Lambert law. The different surface chemistry mechanisms will bring significant effects on the performance of surface chemistry-derived devices such as biochips, biosensors, and biomaterials. 相似文献
35.
采用炭硬模板法制备了高比表面积Cr_2O_3-α-AIF_3催化剂.该催化剂的合成过程主要包括三步:(1)将一定浓度的蔗糖溶液浸渍到Cr_2O_3-γ-Al_2O_3中,然后经过热处理,使得蔗糖分解为炭;(2)将含炭的Cr_2O_3-γ-Al_2O_3固体在400℃用HF气体进行完全氟化;(3)在高温下利用燃烧法除去炭硬模板.对所制备的催化剂进行了X射线衍射(XRD),氮气吸脱附曲线,氨气程序升温脱附(NH_3-TPD),透射电镜(TEM),扫描电镜(SEM)和X射线能量散射(EDX)技术表征.结果表明,氟化过程对Cr_2O_3-α-AIF_3催化剂比表面积有重要影响,在最佳实验条件下,能够得到比表面积为115 m~2·g~(-1)的催化剂.此催化剂对催化裂解二氟乙烷(HFC-152a)制备氟乙烯(VF)的催化活性明显高于直接氟化制备的Cr_2O_3-α-AIF_3催化剂,这是因为高比表面积的Cr_2O_3-α-AIF_3催化剂具有较大的酸量. 相似文献
36.
通过溶剂热方法合成了ZnMn2O4微米空心球,并探讨了其形成机理。采用XRD,SEM,TEM等测试手段对产物的结构、形貌和组成进行了表征。实验结果表明,溶剂热反应条件如反应温度、反应介质对于产物的结构和形貌起着关键作用。在140℃,采用乙醇和水作为反应介质,反应6 h可以制备出直径约3μm的ZnMn2O4微米空心球;当以乙醇为溶剂,反应6 h可以得到团聚的尺寸约250 nm的ZnMn2O4纳米颗粒。将所制备的ZnMn2O4微米空心球/纳米颗粒组装成锂扣式模拟电池,考察其电化学脱嵌锂性能。电化学测试结果显示,与ZnMn2O4纳米颗粒相比,空心结构的ZnMn2O4微米球具有较高的初始放电容量(1335 mAh·g-1)和较好的倍率性能,有望作为锂离子电池的新型负极材料。 相似文献
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39.
‘G4argo', a GEANT4-based simulation package for the ARGO-YBJ detector, is described in this paper. C4argo incorporates in the simulation the true RPC time resolution and another 0.5 ns time uncertainty which is introduced from the offline calibration of TDC. In addition, the correct RPC geometry and the true materials for the ARGO-YBJ experimental hall are implemented. As a result, G4argo simulation shows a very good agreement with real data. 相似文献
40.
Binary naoparticles composed of a superparamagnetic Fe(3)O(4) core and an Au nanoshell were prepared via a high-temperature hydrolysis reaction followed by seed-mediated growth. The nanoprobes render simultaneous dual functions of both fast magnetic response and local surface plasmon resonance. Using these nanoprobes, analyte molecules can be easily biologically captured, magnetically concentrated, and analyzed by surface-enhanced Raman scattering (SERS). Particularly, the complex particles were assembled under magnetic force direction into a SERS substrate. It was found to possess both a high enhancement factor (10(6)) and high homogeneity of "hot spot" distribution (fluctuation less than 20% for a 1 μm(2) area) with 4-aminothiophenol as the analyte. 相似文献