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71.
Xin-Yu Wang Feng-Jie Guan Bin Li Hua Zhang Hong-Wei Wu Kai Ji Chuan-Xiang Liu 《中国化学快报》2016,27(2):211-214
A new chromogenic and fluorescent ‘‘turn-on" chemodosimeter 3 was designed and synthesized by using a fluoride-sensitive self-immolative linker, in combination with the fluorescent dyes 7-hydroxy-4-trifluoromethyl coumarin. The chemodosimeter exhibited high selectivity and sensitivity toward fluoride anions through ‘‘turn-on" chromogenic and fluorogenic dual modes. 相似文献
72.
对966名氟作业工人选定的骨骼常规摄X光片,按其不同日摄氟量分组观片、记录。结果显示:①骨骼X线改变阳性率与日摄氟量呈正相关(r=0.879,P〈0.01);②不同部位的骨骼X线改变阳性率有差异;③骨骼X线改变的主要表现是骨密度增高、骨间膜增宽或钙化、关节、骨周、髓腔有改变、骨质增生、闭孔膜及韧带钙化等。 相似文献
73.
采用离子选择电极法对生活饮用水中氟化物浓度进行了测定。讨论了水样中pH值、温度、响应时间对测定结果的影响。在最佳条件下,方法的线性范围为0.10~3.0mg/L,相关系数为0.9999,检出限为0.05mg/L,实际水样加标回收率为97%~106%,相对标准偏差(n=5)为0.04%~0.65%。方法简单快速,干扰小,重现性好,加标回收率令人满意,能进行生活饮用水中氟化物浓度的有效测定。 相似文献
74.
A novel turn-on fluorescent and colorimetric sensor, N-(4′-nitrophenyl)-2-oxo-6-(phenylazo)-2H-chromene-3-carbohydrazide (1), for fluoride in dimethyl sulfoxide (DMSO) was designed and synthesized. The binding ability evaluated by UV-vis and fluorescence titration experiments reveals that 1 can selectively recognize fluoride. In particular, addition of F− to the DMSO solution of 1 resulted in an enhancement in fluorescence intensity at 338 and 352 nm, which can provide a way of ‘naked-eye’ detection for fluorides. The spectral change of 1 is due to the anion-induced increase of the charge density in and the rigidity of the host molecule. Furthermore, the binding mode with F− was investigated by 1H NMR experiments. 相似文献
75.
76.
E. Balaraman 《Tetrahedron》2009,65(36):7603-5326
A simple transition metal-free hydro/hydrothiophosphonylation of Baylis-Hillman adducts, substituted allyl bromides, allenylphosphonates and alkynes, promoted by fluoride ion in ionic liquid, is described. Clear-cut evidence for fluoride activation of the phosphite via pentacoordinate phosphorus is provided for the first time. Also, in a comparative reaction, the product obtained was different from that from the palladium catalyzed one. Structures of key products are proven by X-ray crystallography. 相似文献
77.
A new ortho-phenylenediamine-based fluorescent cleft 1 has been designed and synthesized. The open cleft of 1 selectively recognizes tetrabutylammonium dihydrogen phosphate in CH3CN by exhibiting a significant decrease in the emission of anthracene. The interactions of 1 are also investigated in aq CH3OH where no measurable change in the emission is observed for tetrabutylammonium dihydrogen phosphate, although sodium salts of phosphate, hydrogen phosphate, and dihydrogen phosphate exhibit moderate changes. Tetrabutylammonium hydrogen sulfate is sensed effectively in aq CH3OH. The anion binding properties of 1 were evaluated by 1H NMR, UV-vis, and fluorescence spectroscopic methods. 相似文献
78.
Amit Bansiwal Dilip Thakre Nitin Labhshetwar Siddharth Meshram Sadhana Rayalu 《Colloids and surfaces. B, Biointerfaces》2009,74(1):216-224
Highly selective material based on naturally occurring biomaterial namely chitosan has been designed for the defluoridation of water. Lanthanum incorporated chitosan beads (LCB) were prepared using precipitation method. The synthesis was optimized by varying different synthesis parameters namely lanthanum loading, complexation and precipitation time, strength of ammonia solution used for precipitation, drying time, etc. Lanthanum incorporated chitosan beads were characterized using SEM, FTIR, XRD and EDX. Surface area of LCB was observed to be 2.76 m2 g−1. The equilibrium adsorption data fitted well to Langmuir adsorption isotherm and showing maximum fluoride adsorption capacity of 4.7 mg g−1 with negligible lanthanum release. Kinetic study reveals that adsorption of fluoride is fast and follows pseudo-first-order kinetics. The effect of pH was also studied and the best efficiency was observed at pH 5. Presence of sulphate, nitrate and chloride marginally affected the removal efficiency, however drastic reduction in fluoride uptake was observed in the presence of carbonate and bicarbonate. Negative value of change in free energy (ΔG°) and positive value of change in entropy (ΔS°) suggest the adsorption of fluoride by LCB is feasible and spontaneous process. Positive value of change in enthalpy (ΔH°) suggests the process of fluoride adsorption is endothermic in nature. Regeneration study reveals that 1 M ammonium chloride solution appears to be the promising regeneration media showing 81.22% regeneration. The adsorption capacity of LCB was similar in fluoride-contaminated ground water collected from Dhar district of Madhya Pradesh, India, as compared to simulated water. 相似文献
79.
Asako Shimada-Fujiwara Akiko Hoshi Yutaka Kameo Mikio Nakashima 《Journal of chromatography. A》2009,1216(18):4125-4127
The dependence of Th recovery on hydrofluoric acid (HF) concentration in nitric acid (HNO3) solutions (1–5 mol/dm3) containing 1 × 10−6 mol/dm3 of Th and various concentrations of HF and the elution behavior were studied using a commercially available UTEVA (for uranium and tetravalent actinide) resin column. Thorium recovery decreased with an increase in HF concentration in the sample solutions. The concentration of HF at which Th recovery started to decrease was ∼1 × 10−4 mol/dm3 in 1 mol/dm3 HNO3 solution, ∼1 × 10−3 mol/dm3 in 3 mol/dm3 HNO3 solution, and ∼1 × 10−2 mol/dm3 in 5 mol/dm3 HNO3 solution. When Al(NO3)3 (0.2 mol/dm3) or Fe(NO3)3 (0.6 mol/dm3) was added as a masking agent for F− to the Th solution containing 1 × 10−1 mol/dm3 HF and 1 mol/dm3 HNO3, Th recovery improved from 1.4 ± 0.3% to 95 ± 5% or 93 ± 3%. Effective extraction of Th using UTEVA resin was achieved by selecting the concentration of HNO3 and/or adding masking agents such as Al(NO3)3 according to the concentration of HF in the sample solution. 相似文献
80.
The relative fluoride donor ability: C6F5BrF2 > C6F5IF2 > C6F5IF4 was outlined from reactions with Lewis acids of graduated strength in different solvents. Fluoride abstraction from C6F5HalF2 with BF3·NCCH3 in acetonitrile (donor solvent) led to [C6F5HalF·(NCCH3)n][BF4]. The attempted generation of [C6F5BrF]+ from C6F5BrF2 and anhydrous HF or BF3 in weakly coordinating SO2ClF gave C6F5Br besides bromoperfluorocycloalkenes C6BrF7 and 1-BrC6F9. In reactions of C6F5IF2 with SbF5 in SO2ClF the primary observed intermediate (19F NMR, below 0 °C) was the 4-iodo-1,1,2,3,5,6-hexafluorobenzenium cation, which converted into C6F5I and 1-IC6F9 at 20 °C. The reaction of C6F5IF4 with SbF5 in SO2ClF below −20 °C gave the cation [C6F5IF3]+ which decomposed at 20 °C to C6F5I, 1-iodoperfluorocyclohexene, and iodoperfluorocyclohexane. Principally, the related perfluoroalkyl compound C6F13IF4 showed a different type of products in the fast reaction with AsF5 in CCl3F (−60 °C) which resulted in C6F14. Intermediate and final products of C6F5HalFn−1 (n = 3, 5) with Lewis acids were characterized by NMR in solution. Stable solid products were isolated and analytically characterized. 相似文献