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51.
水生植被是湿地生态系统的核心,也是影响湿地生态系统功能的最主要因素。近年来,卫星遥感技术在湿地植被资源调查、分类和保护等领域中已得到广泛的应用。由于水生植被独特的生长环境,其冠层光谱会受到水体背景要素包括大气—水界面、水中浮游生物以及泥沙含量、透明度、水体深度、底质和其他光学活性成分的影响,因此遥感技术应用于湿地水生植被冠层光谱研究时,需考虑到水生植被不同于陆生植被的生长环境,这一点在以往的相关研究中并没有得到应有的重视。以典型的挺水植物鸢尾(Iris tectorum Maxim)为研究对象,模拟湿地水生植被的生长环境,使用地物光谱仪测定了鸢尾植被冠层在不同水深梯度背景下的光谱反射率(400~2 400 nm)。实验结果表明,背景水深与鸢尾冠层反射率之间存在着显著的负相关性,其中可见光波段绝对相关系数在0.9以上,近红外波段的绝对相关系数在0.8以上。在可见光和近红外波段,随着背景水深的增加,鸢尾冠层反射率下降均比较明显。最后分别依据可见光和近红外区域相关性最高的波段(505,717,1 075和2 383 nm)建立了背景水深与冠层反射率之间的线性方程,并得出了相关参数。 相似文献
52.
液相色谱-质谱联用法分析检测鳗鱼中4种硝基呋喃代谢物 总被引:2,自引:0,他引:2
建立了液相色谱-质谱联用法(LC-MS)测定鳗鱼中4种硝基呋喃代谢物的快速方法。方法首先采用甲醇水溶液(V甲醇:V水=8:1)粗提鳗鱼中的呋喃唑酮代谢物(AOZ),呋喃它酮代谢物(AMOZ),呋喃西林代谢物(SC)和呋喃妥因代谢物(AH),再用2-硝基苯甲醛(2-NBA)作为衍生剂,使鳗鱼中的这4种硝基呋喃代谢物被成功衍生,并最终实现LC-MS的分离检测。结果表明,本方法高效灵敏,检出限低,AOZ和AMOZ的检出限分别可达到0.08、0.06ng/g,AH和SC的检出限分别为0.16ng/g和0.15ng/g,可很好地运用于鳗鱼企业内部及市场监管部门对水产品中硝基呋喃抗生素代谢物的检测分析。 相似文献
53.
冷冻去脂-固相萃取-气相色谱法快速测定水产品中硫丹、硫丹硫酸酯和溴氰菊酯残留量 总被引:1,自引:0,他引:1
建立了气相色谱快速测定水产品中硫丹、硫丹硫酸酯和溴氰菊酯的残留量的方法。样品经过V(丙酮)∶V(正己烷)=1∶1提取,冷冻去除脂肪后,再用中性氧化铝SPE柱净化,然后用GC-μECD测定,外标法定量。对样品的提取和净化进行了研究和优化。目标化合物在0.005~0.1 mg/L范围内线性良好,相关系数为0.9994~0.9997。在0.005~0.02 mg/kg范围内,平均回收率在78.3%~89.2%,相对标准偏差为4.2%~9.7%。方法可用于水产品中硫丹、硫丹硫酸酯和溴氰菊酯残留量的检验。 相似文献
54.
应用微波等离子体发射光谱(microwave plasma-atomic emission spectrometry, MP-AES)技术, 建立水产饲料中铜、铁、锰、锌、钾、钠等元素MP-AES分析方法。样品采用干灰化法消解, 开展了方法学研究试验, 同时与AAS和ICP-AES方法进行比对, 并完成FAPAS能力验证样品和标准物质确证试验。通过优化MP-AES仪器的各项参数, 在所选定的条件下, 各元素的线性相关系数在0.999以上, 检出限在0.4~3.9 mg·kg-1之间, 加标回收率在103%~112%之间, 精密度试验相对标准偏差在0.2%~0.6%之间;测定结果与AAS法、ICP-AES法比对, 单因素方差分析(α=0.05)各元素P值在0.065~0.438之间, 均大于0.05, 无显著性差异;FAPAS奶牛饲料能力验证和灌木枝叶(GBW07602)标准物质确证试验的各元素测定值均在参考值范围内。结果表明, 所建立的方法简单、快速, 线性范围宽, 具有良好的准确性和精密度;MP-AES无需使用乙炔、氩气, 安全、经济、环保, 能降低检测成本、提高检测效率, 可替代AAS、ICP-AES法测定水产饲料中的六种金属元素, 为水产饲料的质量控制提供理想的元素分析方法。 相似文献
55.
Assessment of cross-flow filtration for the size fractionation of freshwater colloids and particles 总被引:1,自引:0,他引:1
This research has evaluated the ability of cross-flow filtration (CFF) to perform correct size fractionation of natural aquatic colloids (materials from 1 nm to 1 μm in size) and particles (>1 μm) using scanning electron microscopy (SEM) combined with atomic force microscopy (AFM). SEM provided very clear images at high lateral resolution (ca. 2-5 nm), whereas AFM offered extremely low resolution limits (sub-nanometer) and was consequently most useful for studying very small material. Both SEM and AFM were consistent in demonstrating the presence of colloids smaller than 50 nm in all fractions including the retentates (i.e. the fractions retained by the CFF membrane), showing that CFF fractionation is not fully quantitative and not based on size alone. This finding suggests that previous studies that investigated trace element partitioning between dissolved, colloidal and particulate fractions using CFF may need to be re-visited as the importance of particles and large colloids may have been over-estimated. The observation that ultra-fine colloidal material strongly interacted with and completely coated a mica substrate to form a thin film has important potential implications for our understanding of the behaviour of trace elements in aquatic systems. The results suggest that clean, ‘pure’ surfaces are unlikely to exist in the natural environment. As surface binding of trace elements is of great importance, the nature of this sorbed layer may dominate trace element partitioning, rather than the nature of the bulk particle. 相似文献
56.
Michael R. Grace Tracey M. Hislop Barry T. Hart Ronald Beckett 《Colloids and surfaces. A, Physicochemical and engineering aspects》1997,120(1-3):123-141
Laboratory studies have modelled the interaction of Darling River water and a saline groundwater intrusion. Kinetic measurements have shown that the rate determining step in water column clarification is the aggregation of small colloidal particles which then settle rapidly after reaching a critical diameter. Divalent cations (Ca2+ and Mg2+) are extremely effective in enhancing the rate of clarification by increasing the colloid stability factor. Three different phases have been observed in the cation-mediated removal of iron from solution: (i) rapid coagulation induced by the initial velocity shear resulting from solution mixing; (ii) a slower second-order iron removal, consistent with conventional aggregation kinetics; and (iii) a decrease in rate after 90% iron removal which is attributed to a lower iron content in the ultrafine colloid fraction. Specific interactions between the divalent cations and the organic coatings on the particles are proposed in order to explain the much higher rate of coagulation than expected on electrostatic grounds when compared with the monovalent Na+ and K+.
Water column clarification occurred more rapidly in these model laboratory studies than was observed in the Darling River weir pool. Iron removal rates in the river tend to be inhibited by hydrological effects. Turbulence inducing processes are required to mix the dense saline groundwater with the overlying water column and thus may ultimately limit the rate of turbidity reduction. 相似文献
57.
Goveia D Rosa AH Bellin IC Lobo FA Fraceto LF Roveda JA Romão LP Dias Filho NL 《Analytical and bioanalytical chemistry》2008,390(4):1173-1180
This work involved the development and application of a new analytical procedure for in-situ characterization of the lability
of metal species in aquatic systems by using a system equipped with a diffusion membrane and cellulose organomodified with
p-aminobenzoic acid groups (DM-Cell-PAB). To this end, the DM-Cell-PAB system was prepared by adding cellulose organomodified
with p-aminobenzoic acid groups (Cell-PAB) to pre-purified cellulose bags. After the DM-Cell-PAB system was sealed, it was examined
in the laboratory. The in-situ application involved immersing the DM-Cell-PAB system in two different rivers, enabling us
to study the relative lability of metal species (Cu, Cd, Fe, Mn, and Ni) as a function of time and quantity of exchanger.
The procedure is simple and opens up a new perspective for understanding environmental phenomena relating to the complexation,
transport, stability, and lability of metal species in aquatic systems rich in organic matter. 相似文献
58.
为推动锶同位素在水产品溯源中的应用,本文建立了基于电感耦合等离子体质谱法(ICP-MS)测定水产品中锶同位素比值的分析方法。水产品组织经冻干研磨和微波消解后,用ICP-MS测定样品溶液中的锶同位素比值,并采用标准品-样品-标准品交叉测量方法降低质量歧视效应的影响。结果表明,通过稀释样品消解溶液,将总锶浓度控制在70-100 μg/L,并与80 μg/L的锶同位素标准品溶液进行交叉测量,可准确校正质量歧视效应;84Sr/86Sr、87Sr/86Sr和88Sr/86Sr的日内精密度分别为0.06%、0.03%和0.03%,日间精密度分别为0.08%、0.04%和0.03%;按照所建立的方法测定大虾和扇贝生物成分分析标准物质的锶同位素比值,84Sr/86Sr、87Sr/86Sr和88Sr/86Sr的相对标准偏差均低于0.1%。该方法前处理简单快捷并且测量精密度高,可为锶同位素比值测定并进一步应用于水产品溯源研究提供技术支撑。 相似文献
59.
60.
建立了测定水产品中甲基汞和乙基汞的气相色谱质谱联用分析方法。采用6.0 mol/L HCl超声辅助提取,在NaCl存在下,提取液中甲基汞和乙基汞可被甲苯萃取,再用半胱氨酸反萃取,加入CuSO4释放出的甲基汞和乙基汞与四苯硼钠反应,生成甲基苯基汞和乙基苯基汞,经DB-5MS毛细柱分离,选择离子监测方式(SIM)质谱检测,以d3-甲基汞作为内标的稳定同位素稀释法定量。甲基汞和乙基汞标准曲线的线性范围均为1~500μg/L,国家标准参考物质(GBW 10029)6次测定的甲基汞(以汞计)平均值为0.828 mg/kg,相对标准偏差为3.2%,与证书参考值(0.84±0.03)mg/kg(以汞计)一致。鱼、虾和贝类等不同种类水产品中甲基汞和乙基汞的平均加标回收率分别为94%~101%和81%~104%,相对标准偏差在1.9%~4.7%和3.1%~8.2%范围内(n=6),样品的检出限为0.1~0.3μg/kg(S/N=3)。方法灵敏,准确,可用于水产品中甲基汞和乙基汞的测定。 相似文献