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41.
基于三维荧光光谱(3D-EEM)技术,结合荧光区域积分法(FRI)和荧光特征参数,研究了武汉市4种不同类型(河流、湖泊、水源水、雨水)的天然水体中溶解性有机质(DOM)的三维荧光光谱特征,并和近十年武汉东湖相关的研究数据进行了比对.结果表明,5种荧光组分均有检出,分别为类酪氨酸荧光组分(C1)、类色氨酸荧光组分(C2)... 相似文献
42.
《中国化学快报》2023,34(11):108275
The transport of colloids and radionuclides is sophisticated because of the variety of charge properties between colloidal particles and host subsurface media, which causes great difficulty in establishing a reliable model of radionuclides migration by taking the colloid phase into consideration. In this work, the co-transport of illite colloids (IC) and Eu(III) in the quartz sand and iron-coated sand porous media was investigated by column experiments to address the predominant mechanism of charge properties on co-transport. Results showed that Eu(III) transport was driven by the illite colloids and electrostatic interaction was critical in governing the co-transport patterns. The promotion of Eu(III) transport by IC was attenuated in the iron-coated sand systems; more IC-Eu(III) complexes were retained uniformly in the column. The pore throat shrinkage caused by electrostatic attachment between aggregated IC and iron oxides exacerbated the physical straining and size exclusion effect of IC-Eu(III) complexes. An aggravated irreversible retention of IC-Eu(III) was detected in iron-coated sand column due to the electrostatic attraction of IC-Eu(III) to host media. The findings are essential for improving the understanding on the potential transport, retention and release risk of colloids associated radionuclides, and imply that the positively charged permeable reactive barrier is an effective strategy to reduce the transport risk of colloid associated radionuclides. 相似文献
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An experimental study was conducted to investigate the effect of thermal exposure on indentation behavior of carbon fiber reinforced polymer composite sandwich panel (CFRPCSP) with pyramidal truss cores. Composite sandwich panels were fabricated by the hot press molding method. Subsequently, composite sandwich panels were exposed to different temperatures for 6 h. After thermal exposure, quasi-static indentation tests were carried out at room temperature. Then, the effect of thermal exposure on the failure mechanism, indentation load and energy absorption were analyzed and discussed. The results showed that the indentation load and energy absorption decreased as exposure temperature increased, which was caused by the degradation of the matrix properties and fiber-matrix interface properties at high temperature. In addition to the decrease of the indentation load and energy absorption, the failure modes also changed with exposure temperature. It is expected that this study can provide useful information for the design and application of composite sandwich panel with pyramidal truss cores at high temperature. 相似文献
45.
Bing Shao Xiaoyan Wu Jing Zhang Hejun Duan Xiaogang Chu Yongning Wu 《Chromatographia》2009,69(9-10):1083-1088
This contribution presents a simple, rapid and sensitive method for determining the residues of a wide variety of coccidiostats in eggs and chicken. Fourteen target analytes from different classes with different polarities were simultaneously extracted from eggs and chicken using acetonitrile. Sample extracts were further concentrated and directly injected into a liquid chromatography system based on a C-18 column separation and acquired using electrospray ionization tandem mass spectrometry in the positive or negative mode. Recoveries based on matrix-fortified calibrations for eggs and chickens ranged from 78.0 to 125.2%. The limits of quantification for all analytes ranged from 0.1 to 0.2 μg kg?1. 相似文献
46.
Guozhu Liu Naiyuan Zhou Mingshan Zhang Shengjun Li Qingqing Tian Jitao Chen Bo Chen Yongning Wu Shouzhuo Yao 《Journal of chromatography. A》2010,1217(3):243-249
Novel sample preparation approaches for HPLC bioanalysis based on the phenomenon that acetonitrile can be separated from water by adding salts or cooling at subzero temperatures have been reported. These two methods are superior to conventional liquid–liquid extraction since the separated acetonitrile phase can be directly injected to the RP–LC system. However, the salting-out method suffers from a potential problem that the remained salt in the acetonitrile phase may harm the MS detector, while the subzero-temperature method is troublesome to operate. Here, we have reported a similar phase separation phenomenon that the acetonitrile aqueous mixture can be separated by adding a hydrophobic solvent; and capitalising on this phase transition phenomenon, we have proposed an alternative approach, named solvent induced phase transition extraction (SIPTE), to extract drug from plasma for HPLC–MS analysis. The proposed SIPTE method is much simpler and avoids contaminating the MS detector. Three structurally diverse drugs were selected as test compounds to design the SIPTE method and to validate the efficiency of this method. The four goals of plasma sample pretreatment for HPLC–MS analysis, i.e. removal of proteins, removal of other low-molecular interferences, preconcentration of the analytes of interest, and matching the sample solvent with the HPLC–MS system, can be rapidly performed in a very simple step by using the SIPTE method. 相似文献
47.
高效液相色谱-线性离子阱质谱法测定畜禽肌肉中β2-受体激动剂及β-阻断剂类药物残留 总被引:1,自引:0,他引:1
利用高效液相色谱-线性离子阱质谱(HPLC-ITMS)以同位素稀释技术测定了肌肉组织中23种β2-受体激动剂及5种β-阻断剂.肌肉样品经5%的三氯乙酸溶液酸解提取,以弱阳离子固相萃取柱进行净化.以甲醇和含0.1%甲酸的水溶液为流动相在液相色谱柱上梯度洗脱分离,采用ESI源正离子模式在选择离子监测(SRM)模式下进行扫描.以9种经氘代同位素标记的β2-受体激动剂为内标进行定量.猪肉中23种β2-受体激动剂及5种β-阻断剂的线性范围为5-200μg/L,相关系数(力大于0.995,各化合物在肌肉中的检出限均能达到0.2gg/kg.以空白猪肉样品进行的加标水平为5、10、20μg/kg的加标回收试验,各化合物的回收率在47.3%-123.7%之间,相对标准偏差在3.2%~25.7%之间.对猪肉样品和鸡肉样品进行了测定,得到了满意的结果.该方法灵敏度高,定性准确,可以用于畜禽肌肉中β2-受体激动剂和β-阻断剂类药物残留的确证检测. 相似文献
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49.
A piece of domestic polarization-maintaining photonic crystal fiber (PM-PCF, 964 m in length) is made into a fiber coil, and its polarization extinction ratio (PER) is measured in a temperature range of -45- 80 C before and after PM-PCF is wound and solidified. A fiber coil made of commercial panda PM fiber (PMF) is also fabricated and measured for comparison. Our experiments show that the PER variation of the PM-PCF coil (2.25 dB) is far smaller than that of the panda PMF coil (10 dB) in the whole temperature range because PM-PCF is intrinsically insensitive to the temperature variation and stress in the fiber coil induced by the winding and solidification process. This characteristic is important for the real application of PM-PCFs in temperature-insensitive fiber interferometers, fiber sensors, and optical fiber gyroscopes. 相似文献
50.
A selective and sensitive isotope dilution–high performance liquid chromatography–linear ion trap mass spectrometry (Isotope Dilution–HPLC–LIT-MS3) method was developed for the simultaneous determination of 19 triazine pesticides and their degradation products in processed cereal samples from Chinese total diet study (TDS). The method integrated the addition of isotope internal standards, liquid–liquid extraction (LLE), clean-up with MCX solid-phase extraction (SPE) cartridges and HPLC–LIT-MS3 analysis with selected reaction monitoring (SRM) mode. Matrix-matched calibration curves showed good linearity (R2 ≥ 0.9940) verified by applying the Mandel's fitting test (p > 0.087) performed at the 95% confidence level. Decision limits (CCαs) and detection capabilities (CCβs) of the 19 triazine pesticides and their degradation products fell in the ranges of 0.0020–0.4200 μg kg−1 and 0.0024–0.4500 μg kg−1, respectively. Recoveries ranged from 70.1% to 112.8%, with the relative standard deviations (RSDs) ranging from 1.5% to 13.5%. Furthermore, the proposed method was applied to analyzing the proposed cereal samples from the fourth Chinese TDS. Eleven triazines were detected in six cereal samples with the concentrations ranging from 0.013 to 0.987 μg kg−1. This method can also be used for the further determination of the triazines in other food group composites, and ultimately served as a methodological foundation for assessing the triazines in the average Chinese diet in the general population. 相似文献