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271.
W. Chen X. L. Xu P. Zhou Y. M. Cui Y. G. Li 《Russian Journal of Coordination Chemistry》2013,39(3):301-304
Two silver(I) compounds, [Ag(R,R-hxn)](C7H4BrO2) · 2H2O (I) (Chxn = 1,2-diaminocyclohexane) and [Ag(C5H6N2)2]2(C8H4O4) · 10H2O (II), were synthesized and complex I was structurally characterized by X-ray crystallography. Compound I contains a catena-(trans-1,2-diaminocyclohexane) silver polycation ([Ag(Chxn)]∞) in a roughly linear fashion, while II possesses a linear-type silver monocation. Compounds I and II were evaluated for their inhibitory activities against Helicobacter pylori urease in vitro. Both were found to have strong inhibitory activities against H. pylori urease comparable to that of acetohydroxamic acid. 相似文献
272.
Anatoli Tchigvintsev Dmitri Tchigvintsev Robert Flick Ana Popovic Aiping Dong Xiaohui Xu Greg Brown Wenyun Lu Hong Wu Hong Cui Ludmila Dombrowski Jeong Chan Joo Natalia Beloglazova Jinrong Min Alexei Savchenko Amy A. Caudy Joshua D. Rabinowitz Alexey G. Murzin Alexander F. Yakunin 《Chemistry & biology》2013,20(11):1386-1398
273.
274.
Hierarchical ZSM-11 with intergrowth structures:Synthesis,characterization and catalytic properties 总被引:1,自引:0,他引:1
Qingjun Yu Chaoyue Cui Qiang Zhang Jing Chen Yang Li Jinpeng Sun Chunyi Li Qiukai Cui Chaohe Yang Honghong Shan 《天然气化学杂志》2013,(5):761-768
Hierarchical ZSM-11 microspheres with intercrystalline mesoporous properties and rod-like crystals intergrowth morphology have been synthesized using a spot of tetrabutylammonium as a single template.XRD,FTIR,SEM,TEM and N2 adsorption analysis revealed that each individual particle was composed of nanosized rod crystals inserting each other and the intercrystalline voids existing among rods gave a significant mesopore size distribution.Steam treatment result demonstrated the excellent hydrothermal stability of samples.Various crystallization modes including constant temperature crystallization (one-stage crystallization) and two-stage temperature-varying crystallization with different 1st stage durations were investigated.The results suggested that the crystallization modes were mainly responsible for the adjustable particle size and textural properties of samples while the small amount of tetrabutylammonium bromide was mainly used to direct the formation of both ZSM-11 framework and its intergrowth morphology.Furthermore,the performance of optimal ZSM-11 as an active component for the catalytic pyrolysis of heavy oil was also investigated.Compared with the commercial pyrolysis catalyst,the hierarchical ZSM-11 catalyst exhibited a high selectivity to desired products(LPG+gasoline+diesel),as well as a much lower dry gas and coke yield,plus a high selectivity and yield of light olefins(C=3 C=4)and very poor selectivity to benzene.Therefore,fully open micropore-mesopore connectivity would make such hierarchically porous ZSM-11 zeolites very attractive for applications in clean petrochemical catalysis field. 相似文献
275.
Chunlei Wang Shuhong Xu Yujie Shao Zhuyuan Wang Yiping Cui 《Journal of Cluster Science》2013,24(2):439-447
In this paper, conformations of the ternary structures ZnSe(Te), ZnS(Te), ZnS(Se), CdSe(Te), CdS(Te) and CdS(Se) were optimized, and their orbital, spectra have been investigated at the B3LYP/LANL2DZ level. First, we have found some rules which agreed with experimental results. HOMO–LUMO gaps, WBI values and the wavelengths of the absorption peaks of ternary structures changed gradually with the ratio of Te, Se and S atoms in ternary structures. Second, analysis of Raman spectra revealed that doped structures had the spectra of two relevant binary clusters. Namely, Raman spectra of ternary ZnSe(Te) clusters had the Raman peaks of ZnSe and ZnTe. In this way, with the help of the Raman spectra, the formations of the ternary structures can be determined in experiment. This was important to estimate during synthesis progress. Finally, calculated results have proved that ZnS and CdS structures had the shorter wavelengths of the absorption peaks, the higher excited energies of singlets, and good stability. 相似文献
276.
The B3LYP/6-31G** method was used to investigate IR and Raman spectra, heat of formation, and thermodynamic properties of a new designed polynitro cage compound 1,3,5,7,9,11-hexanitrotetradecahydro-1H-1,3,4,5,7,7b,9,11,12a,12b1,12b2,13-dodecaaza-4,8,12-(epimethanetriyl)cyclohepta[l]cyclopenta[def]phenanthrene. The detonation and pressure were evaluated using the Kamlet–Jacobs equations based on the theoretical density and HOFs. The bond dissociation energies and bond orders for the weakest bonds were analyzed to investigate the thermal stability of the title compound. The results show that N8–NO2 bond is predicted to be the trigger bond during pyrolysis. There exists an essentially linear relationship between the WBIs of N–NO2 bonds and the charges – $ Q_{{{\text{NO}}_{ 2} }} $ on the nitro groups. The crystal structure obtained by molecular mechanics belongs to the P21 space group, with lattice parameters Z = 2, a = 11.4658 Å, b = 15.2442 Å, c = 10.2451 Å, ρ = 2.07 g cm?3. The designed compound has high thermal stability and good detonation properties and is a promising high-energy density compound. 相似文献
277.
278.
Chhavi Bhardwaj Jerry F. Moore Yang Cui Gerald L. Gasper Hans C. Bernstein Ross P. Carlson Luke Hanley 《Analytical and bioanalytical chemistry》2013,405(22):6969-6977
Laser desorption postionization mass spectrometry (LDPI-MS) imaging is demonstrated with a 10.5 eV photon energy source for analysis and imaging of small endogenous molecules within intact biofilms. Biofilm consortia comprised of a synthetic Escherichia coli K12 coculture engineered for syntrophic metabolite exchange are grown on membranes and then used to test LDPI-MS analysis and imaging. Both E. coli strains displayed many similar peaks in LDPI-MS up to m/z 650, although some observed differences in peak intensities were consistent with the appearance of byproducts preferentially expressed by one strain. The relatively low mass resolution and accuracy of this specific LDPI-MS instrument prevented definitive assignment of species to peaks, but strategies are discussed to overcome this shortcoming. The results are also discussed in terms of desorption and ionization issues related to the use of 10.5 eV single-photon ionization, with control experiments providing additional mechanistic information. Finally, 10.5 eV LDPI-MS was able to collect ion images from intact, electrically insulating biofilms at ~100 μm spatial resolution. Spatial resolution of ~20 μm was possible, although a relatively long acquisition time resulted from the 10 Hz repetition rate of the single-photon ionization source. Figure
Neutral species laser desorbed from cocultured biofilms undergo single photon ionization by VUV radiation and resultant ions are detected by time-of-flight mass spectrometry 相似文献
279.
Cui Yang Chunyan Ren Xiangfan Piao Narayanan Kannan Donghao Li 《Journal of separation science》2013,36(21-22):3599-3607
A continuous‐flow, on‐line sample pretreatment technique using a silica gel microsyringe extractor has been developed. All steps including extraction, separation, clean‐up, and concentration occur in the microsyringe. The overall sample pretreatment process takes <10 min per sample. Different polarity chemicals in the plant sample are successively extracted and separated, and analyzed in parallel using HPLC–UV and HPLC–UV–MS/MS. Polycyclic aromatic hydrocarbons, alkylphenols, and plant hormones were determined as model compounds for nonpolar, intermediate polarity, and polar fractions, respectively. All the parameters that influence the extraction and separation efficiency of the microsyringe extractor have been optimized and evaluated. Under the optimized conditions, recoveries of target compounds ranged from 78.4 to 101.9%, the RSD was <12.8% and the square of the correlation coefficient was >0.99. Complex plant samples of Sambucus Mandshurica Kitag have been tested using this method. Fluorene, phenanthrene, pyrene, and plant hormones were detected in all the samples, and concentrations ranged from 24.2–34.9, 43.8–67.1, 25.9–29.2, and 14.5~110.8 ng/g, respectively. 相似文献
280.
Jiamin Gu Reihong Feng Zhiyuan Wu Shuguang Guan Jiling Guo Chunru Cheng Pingping Xu Jingxian Zhang Yang Wang Hua Qu Wei Man Wenbo Yu Yajun Cui Shuhong Guan Dean Guo 《Journal of separation science》2013,36(14):2366-2372
A rapid and convenient method was established to preparatively isolate the three ellagic acid types of compounds, which were the main polyphenols in Euphorbia pekinensis, by flexibly applying solvent extraction combined with counter‐current chromatography (CCC). The total extract (extracted using 95% ethanol) of E. pekinensis was pretreated by two simple steps before CCC isolation, following the procedure: the total extract was extracted by classical solvent extraction using petroleum ether and ethyl acetate, respectively, and then the ethyl acetate extract was suspended using 95% ethanol, after being allowed to stand overnight, the sediment was obtained. Partial sediment (100 mg) was then directly separated by CCC with a two‐phase solvent system composed of chloroform‐95% ethanol‐water‐85% formic acid (50:50:50:5, v/v/v/v). About 22 mg of 3,3′‐dimethoxy ellagic acid (1), 12 mg of 3,3′‐di‐O‐methyl‐4‐O‐(β‐d ‐xylopyranosyl)ellagic acid (2), and 35 mg of ellagic acid (3) with purities of 96.0, 95.2, and 95.4% were obtained respectively in one step within 4 h. After being purified by washing with methanol, the purities of the three compounds obtained were all above 98%. The purities were determined by HPLC and their chemical structures were further identified by 1H and 13C NMR spectroscopy. The recoveries were calculated as 84.6, 85.7, and 89.5%, respectively. The result demonstrated that the present isolation method was rapid, economical and efficient for the preparative separation of polyphenols from E. pekinensis. 相似文献