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31.
32.
S.?FrangerEmail author P.?Berthet J.?Berthon 《Journal of Solid State Electrochemistry》2004,8(4):218-223
Ultrafine magnetite particles are prepared through an electrochemical process, at room temperature, from an iron-based electrode immersed in an alkaline aqueous medium containing complexing compounds. XRD and chemical analysis indicate that the product is pure magnetite, Fe3O4. The size and morphology of the particles are studied by SEM. The magnetite nanoparticles present a magnetoresistance of almost 3%, at 300 K, under a magnetic field of 1 T. A reactive mechanism for the electrochemical process is proposed. 相似文献
33.
《Electroanalysis》2005,17(12):1097-1102
The inorganic‐organic hybrid polyoxometalates (POMs), (pbpy)4H[PMo12O40(VO)] ( 1 ) and (pbpy)4H4[SiMo12O40] ( 2 ) (pbpy=5‐phenyl‐2‐(4‐pyridinyl)pyridine), have been synthesized and were, respectively, used as a solid bulkmodifier to fabricate a three‐dimensional bulk‐modified carbon paste electrode (CPE) by direct mixing. The electrochemical behavior and electrocatalysis of 1 and 2 modified CPE ( 1 ‐CPE and 2 ‐CPE) have been studied in detail. Both 1 ‐CPE and 2 ‐CPE show remarkable stability that can be ascribed to the doped organic conjugated pbpy, which is very important for practical applications in electrode modification. 相似文献
34.
Renner S Prohaska V Gerber C Niethammer D Bruchelt G 《Journal of chromatography. A》2001,920(1-2):247-253
A method for the quantitative determination of the major anionic constituents of fountain solutions, typically mono-, di- and hydroxycarboxylates, alkylbenzenesulfonates, and inorganic anions, including orthophosphate and polyphosphates, is presented here for the first time. The analytical problems arising from extensive co-elution of many of these analytes on an ion-exchange column have been resolved through a combination of (i) careful selection of the concentration gradient of the sodium hydroxide eluent; (ii) parallel analysis by ion-exclusion chromatography; and (iii) determination of total phosphorus by inductively coupled plasma atomic emission spectrometry. 相似文献
35.
笼形聚偕胺肟树脂的研究HX/ACAO树脂吸附贵金属 总被引:3,自引:0,他引:3
氢卤酸、硝酸、硫酸、磷酸和硼酸处理的笼形聚偕胺肟树脂(HX/A-CAO)对Ag+和等贵金属离子的吸附能力按如下顺序:PdCl42-:H3BO3/ACAO>BCAO>H3PO4/ACAO>HI/ACAO>H2SO4/ACAO>HCl/ACAO>HNO3/ACAO>HF/ACAO.IrCl62-:BCAO>H3PO4/ACAO>H3BO3/ACAO>HCl/ACAO>HF/ACAO>HI/ACAO>H2SO4/ACAO≥HNO3/ACAO.PtCl62:BCAO>H3BO3/ACAO>H2SO4/ACAO>HNO3/ACAO>HCl/ACAO>HF/ACAO>H3PO4/ACAO>HI/ACAO.Ag+:BCAO>H3BO3/ACAO>HI/ACAO>H2SO4/ACAO>HF/ACAO>HCl/ACAO>H3PO4/ACAO>HNO3/ACAO.AuCl4-:BCAO>H3BO3>H3PO4/ACAO>HF/ACAO>HCl/A-CAO>H2SO4/ACAO>HI/ACAO>HNO3/A-CAO.研究了H3BO3/ACAO树脂对Ag+和离子的吸附动力学,讨论了吸附机理. 相似文献
36.
Michael Krachler Hendrik EmonsCarlo Barbante Giulio CozziPaolo Cescon William Shotyk 《Analytica chimica acta》2002,458(2):387-396
Four analytical approaches, based on different physical principles, for the determination of antimony (Sb) and arsenic (As) in ancient peat samples were critically evaluated: (a) open vessel digestion/hydride generation-atomic absorption spectrometry (HG-AAS), (b) closed-pressurized digestion in a microwave oven followed by sector field-inductively coupled plasma-mass spectrometry (SF-ICP-MS), (c) digestion in a microwave autoclave and subsequent quadrupole-inductively coupled plasma-mass spectrometry (Q-ICP-MS) measurements and (d) instrumental neutron activation analysis (INAA). The quality control scheme applied, always included the use of adequate plant reference materials to ensure the accuracy and precision of the analytical procedures. Additionally, two internal peat reference materials were analyzed using all four analytical approaches, generally showing good agreement for both elements. Method detection limits for As and Sb provided by all procedures were approximately 5 and 2 ng g−1 which is sufficiently low for the reliable quantification of both elements in ancient, pre-anthropogenic peat samples. A comparison of As and Sb concentrations in a set of peat samples determined by INAA, HG-AAS and SF-ICP-MS revealed that INAA underestimated the values in a systematic manner, whereas HG-AAS and SF-ICP-MS data agreed very well. Best precision of the results was obtained by analytical procedures involving HG-AAS or Q-ICP-MS and varied from 3.6 to 4.3% and 7.1 to 7.5% for As (at about 0.5 μg g−1) and Sb (at about 0.1 μg g−1), respectively. The highest sample throughput (40 samples per run accomplished in 2 h) combined with low risk of sample contamination could be realized in the high-pressure microwave autoclave. The amount of sample required by all approaches was 200 mg, except for INAA which needed at least 25 times more sample mass to achieve comparable detection limits. For the quantification of As and Sb, inductively coupled plasma-mass spectrometry (ICP-MS) was preferred over INAA and HG-AAS, mainly because (a) less sample is needed and (b) As and Sb can be determined simultaneously. In addition, ICP-MS offers the possibility to measure concurrently a wide range of other elements which also are of environmental interest. 相似文献
37.
无机胶体法制备Pt/C催化剂及其性能表征 总被引:3,自引:0,他引:3
采用无机胶体法制备用于质子交换膜燃料电池(PEMFC)的Pt/C催化剂。研究了影响PtO2胶体生成和稳定性的因素(溶液的pH值、浓度和温度条件等)以及不同还原剂浓度对Pt/C催化剂性能的影响。透射电子显微镜测试结果表明,采用经优化的工艺条件所制备的Pt/C催化剂平均粒径为3 nm,且分散性好、粒度均匀。X-射线衍射分析表明,催化剂中Pt(111)晶面的相对含量较高,有利于加速氧还原反应。单体PEMFC的电压/电流密度曲线测试表明,所制备的Pt/C催化剂具有良好的电化学性能。 相似文献
38.
南药巴戟天中十二种无机元素与药效关系的进一步研究 总被引:4,自引:0,他引:4
在初步研究的基础上,进一步研究了不同产地巴戟天的无机元素含量差异,通过对比各元素含量、相关系数及TE图谱,说明地道药材与非地道药材的巴戟天,其特征元素的含量存在非常明显的差异,要使大面积扩种的药材提高药效,建议根据当地土壤含Mn、Fe、Cr、Co、Ni的含量,以旋微量元素肥料的方法来补充这些元素在土壤中的不足。但在微量元素肥料配方中,应注意巴戟天吸收土壤中的元素时的协同作用和拮抗作用。 相似文献
39.
Arsenic (As) is a toxic trace element that occurs naturally in groundwater and soils. Understanding the reactions of arsenite
(As(III)) and arsenate (As(V)) with soil and mineral surfaces is critical for predicting the fate and transport of As in the
environment and developing better ways to remediate As-contaminated areas. This investigation uses X-ray absorption near edge
spectroscopy (XANES) to evaluate the solid phase oxidation state and mineral surface binding sites in three agricultural soil
samples from California, USA by fitting linear combinations of XANES spectra derived from several synthetic and well characterized
As(III)- and As(V)-treated model compounds (Fe and Al metal hydroxides and aluminosilicate illite clay mineral). The results
suggest that As(III) is either partially or completely oxidized to As(V) when reacted with soil in an aqueous, batch reaction.
The As(III)-treated Aiken soil was composed of 60% As(III) attached to surfaces similar to lepidocrocite (γ-FeOOH)) and 40%
As(V) attached to aluminosilicate (illite). The Fallbrook soil completely oxidized As(III) and the product was As(V) adsorbed
on Al hydroxide (gibbsite, γ-Al(OH)3) (62%), illite (16%), and lepidocrocite (γ-FeOOH) (22%). The reaction of As(III) with Wyo soil resulted in 42% As(III) adsorbed
on surface similar to goethite and 58% As(V) adsorbed on lepidocrocite. Arsenic(V) adsorption on soil resulted in stable As(V)
surface complexes that were well described by XANES spectra from As(V) adsorption complexes on gibbsite, illite, and lepidocrocite. 相似文献
40.
The use of wet and dry ashing procedures to decompose marine biological tissues and to degrade organoarsenic compounds to inorganic arsenic for analysis by zinc-column arsine generation and atomic-absorption spectrophotometry was investigated. Wet ashing with nitric, sulphuric and perchloric acids (10:2:3 v/v) released the largest percentage of arsenic from fish tissue and quantitatively degraded methylated and other organoarsenic compounds to inorganic arsenic. The arsenic concentrations found when standard reference materials were ashed with this acid mixture were in agreement with the certified values. 相似文献