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1.
该研究利用超高效液相色谱-串联四极杆静电场轨道阱高分辨质谱(UHPLC/ESI-Q-Orbitrap)技术,对硒代蛋氨酸(SeMet)的色谱信息、分子离子质荷比和碎裂片段的质荷比进行采集,并对特征离子碎裂途径进行解析,建立了豆类中硒代蛋氨酸的检测方法。样品用三羟甲基氨基甲烷-盐酸(Tris-HCl)缓冲溶液溶解后,涡旋混匀,超声提取,在恒温水浴条件下酶解,离心后取上清液过0.22μm滤膜后上机检测。采用Hypersil GOLD HILIC(50 mm×2.1 mm,1.9μm)色谱柱进行分离,以0.2%(体积分数,下同)甲酸6 mmol/L甲酸铵水溶液和0.2%甲酸6 mmol/L甲酸铵乙腈溶液为流动相梯度洗脱,采用电喷雾正离子模式电离,在全扫描/数据依赖扫描模式(Full MS/dd-MS2)下进行检测,基质匹配标准校正法定量。结果表明,硒代蛋氨酸的基质效应为15.75%,在0.05~0.5 mg/L范围内线性关系良好,相关系数(r2)为0.9976,方法检出限(LOD)为0.015 mg/kg,定量下限(LOQ)为0.05 mg/kg;空白样品在0.1、0.2、0.4 mg/kg 3个加标水平下的平均回收率为77.6%~83.2%,日内相对标准偏差(RSDr)为2.8%~4.8%,日间相对标准偏差(RSDR)为4.1%~6.5%。将方法应用于实际样品的检测,得富硒黑豆、富硒红豆、富硒绿豆中硒代蛋氨酸的含量分别为0.252、0.163、0.184 mg/kg。该方法具有前处理操作简单、结果准确、重复性好等优点,适用于豆类中硒代蛋氨酸的检测。  相似文献   
2.
Quality control plays a key role in the application of Chinese materia medica, especially in the preparation of traditional Chinese medicine. A pseudotargeted analysis method using an ultra-high-performance liquid chromatography-quadrupole-time-of-flight-mass spectrometry that was operated in the sequential window acquisition of all theoretical spectra mode was proposed to explore the chemical markers of traditional Chinese medicine preparation. Full-scan-based untargeted analysis was applied to extract the target ions. After data preprocessing, 302 target ions were extracted and used for the subsequent sequential window acquisition of all theoretical spectra analyses. The established sequential window acquisition of all theoretical spectra-based pseudotargeted approaches exhibited good repeatability and a wide linear range. The established method was successfully applied to discover analytical markers for the Yuanhu Zhitong tablet. After multivariate statistical analysis, 94 potential markers were identified. Ten markers were annotated by matching accurate m/z and product ion information obtained from previous reports. It is clearly indicated that the pseudotargeted analysis could make a great contribution to the quality assessment of traditional Chinese medicine preparation as a newly emerging technique.  相似文献   
3.
Flunitrazepam (FNZ) is a potent hypnotic, sedative, and amnestic drug used to treat severe insomnia. In our recent study, FNZ metabolic profiles were investigated carefully. Six authentic human urine samples were purified using solid phase extraction (SPE) without enzymatic hydrolysis, and urine extracts were then analyzed by liquid chromatography‐Q exactive‐HF hybrid quadrupole‐Orbitrap‐mass spectrometry (LC‐QE‐HF‐MS), using the full scan positive ion mode and targeted MS/MS (ddms2) technique to make accurate mass measurements. There were 25 metabolites, including 13 phase I and 12 phase II metabolites, which were detected and tentatively identified by LC‐QE‐HF‐MS. In addition, nine previously unreported phase II glucuronide conjugates and four phase I metabolites are reported here for the first time. Eight metabolic pathways, including N‐reduction and O‐reduction, N‐glucuronidation, O‐glucuronidation, mono‐hydroxylation and di‐hydroxylation, demethylation, acetylation, and combinations, were implicated in this work, and 2‐O‐reduction together with dihydroxylation were two novel metabolic pathways for FNZ that were identified tentatively. Although 7‐amino FNZ is widely considered to be the primary metabolite, a previously unreported metabolites (M12) can also serve as a potential biomarker for FNZ misuse.  相似文献   
4.
In this study, a convenient and sensitive analytical method based on dispersive solid-phase extraction (dSPE) and gas chromatography-tandem mass spectrometry in tandem was developed for the simultaneous determination of six chloroacetamide herbicides (acetochlor, alachlor, metolachlor, metazachlor, butachlor and pretilachlor) in soil. Parameters that could influence the extraction efficiency such as the varieties of solvents, the amount of solvents and sorbents were investigated. The optimized extractions were performed by mixing 5.0 g of dried soil with 10.0 mL acetonitrile, 10.0 mL deionized water and 4.0 g sodium chloride, and then the extract was purified with 50.0 mg N-propyl ethylenediamine (PSA), 50.0 mg C18, 10.0 mg graphitized carbon black (GCB) and 100.0 mg MgSO4 (5:5:1:10). At 5.0, 25.0 and 100.0 ng g?1 fortification levels for each analyte, the average obtained recoveries ranged from 87.7% to 108.0% with relative standard deviation (RSD) between 3.8% and 10.9%. The soil matrix effect of the six compounds were lower than 11.0%. The linear relation was observed in the range of 5.0–500.0 ng g?1 and the correlation coefficient (R2) of these compounds were higher than 0.998. The detection limits (LODs) were in the range of 0.2–1.0 ng g?1, and the limits of quantification (LOQs) were between 0.8 and 2.2 ng g?1. Comparing with the gas chromatography-electron capture detector (GC-ECD), the GC-tandem mass spectrometry (MS/MS) method can improve the anti-interference ability and thus get better separation of the chloroacetamide herbicides. Additionally, this method was verified to fit for soil samples with broad organic matter range (16.2 to 83.0 g kg?1). The developed method was successfully applied for analysing 26 field soil samples collected from Dianchi lake basin in the southeast of China. About 42.0% soil samples were detected with these herbicides, of which butachlor was the most frequently detected and the highest concentration was up to 137.0 ng g?1 in rape soil.  相似文献   
5.
The application of electron transfer and dipolar direct current induced collisional activation (ET‐DDC) for enhanced sequence coverage of peptide/protein cations is described. A DDC potential is applied across one pair of opposing rods in the high‐pressure collision cell of a hybrid quadrupole/time‐of‐flight tandem mass spectrometer (QqTOF) to induce collisional activation, in conjunction with electron transfer reactions. As a broadband technique, DDC can be employed for the simultaneous collisional activation of all the first‐generation charge‐reduced precursor ions (eg, electron transfer no‐dissociation or ETnoD products) from electron transfer reactions over a relatively broad mass‐to‐charge range. A systematic study of ET‐DDC induced collision activation on peptide/protein cations revealed an increase in the variety (and abundances) of sequence informative fragment ions, mainly c‐ and z‐type fragment ions, relative to products derived directly via electron transfer dissociation (ETD). Compared with ETD, which has low dissociation efficiency for low‐charge‐state precursor ions, ET‐DDC also showed marked improvement, providing a sequence coverage of 80% to 85% for all the charge states of ubiquitin. Overall, this method provides a simple means for the broadband collisional activation of ETnoD ions in the same collision cell in which they are generated for improved structural characterization of polypeptide and protein cations subjected to ETD.  相似文献   
6.
Tricaine methanesulfonate is one of most commonly used anesthetics in fish during blood sampling, artificial propagation and long‐distance transportation. In this study, an accurate method for the quantitative determination of tricaine in fish samples by a stable isotope dilution assay coupled with high‐performance liquid chromatography–triple quadrupole mass spectrometry was developed. Tricaine‐D5 was synthesized and used as an isotopically labeled internal standard for the determination of tricaine. The analytical performance of the method was validated for tricaine determination in marine fish and freshwater fish. The determination of tricaine was linear in the range of 2.0–200.0 μg L?1. The limit of detection and limit of quantitation for fish muscle tissues were 1.0 and 4.0 μg kg?1, respectively. Good recoveries were obtained in the range of 92.08–97.50%. The inter‐ and intra‐assay relative standard deviations (RSD values) were investigated, and the values were 0.39–3.01 and 0.85–2.77%, respectively. The values of CCα and CCβ were 10.21–10.43 and 10.42–10.87 μg kg?1, respectively. The clearance of MS‐222 from grass carp was further studied using our method. The results demonstrate that MS‐222 could be well absorbed and rapidly eliminated after bath administration.  相似文献   
7.
Monodisperse silica spheres that comprised a rhombic‐dodecahedral zeolitic imidazolate framework core–shell microsphere were applied in the sample pretreatment of navel orange. A rapid and efficient liquid chromatography with triple quadrupole tandem mass spectrometry method was established for simultaneously quantifying four plant growth regulators, 6‐benzylaminopurin, indole‐3‐acetic acid, indolepropionic acid, 3‐indolebutyric acid, in navel oranges. A satisfactory result was obtained, i.e., the peak area of the four plant growth regulators against concentration was linear with good correlation coefficients of 0.99987–0.99991. Under optimized conditions, the limits of detection were 3.0–59.4 μg/L for the four plant growth regulators. This method was applied to the simultaneous analysis of the four plant growth regulators in commercial samples, and all the detections were confirmed by acquiring transitions for each pesticide in the samples.  相似文献   
8.
Tetrodotoxin is a marine biotoxin with high acute toxicity. The levels in cooked seafood will help us to assess its intake in humans and may help assess the risk of toxicity. However, heavy matrices hinder the direct quantitation of tetrodotoxin. A quantitative method of measuring tetrodotoxin in cooked seafood using liquid chromatography with triple quadrupole mass spectrometry was established in this study. Tetrodotoxin was extracted from the sample matrix using 2% formic acid in methanol and cleaned using a cation exchange cartridge. The cleanup conditions were optimized. The matrix effects were determined using the postextraction spiking method and by comparing the slope of the linear regression equation in sample matrix to that in solvent. The limit of detection in the sample matrix was 5 μg/kg and the limit of quantification was 10 μg/kg. The mean recoveries at three spiking levels were 66.9–89.2% with relative standard deviations of 5.0–10.8% (n = 6) in five different matrices. Tetrodotoxin was found at concentrations of 26.1–2462 μg/kg in nine of 83 cooked seafoods tested in this study. Eight analogs of Tetrodotoxin were detected in the samples studied.  相似文献   
9.
The gas‐phase structures and parameters describing acetyl methyl torsion of N‐ethylacetamide are determined with high accuracy, using a combination of molecular beam Fourier‐transform microwave spectroscopy and quantum chemical calculations. Conformational studies at the MP2 level of theory yield four minima on the energy surface. The most energetically favorable conformer, which possesses C1 symmetry, is assigned. Due to the torsional barrier of 73.4782(1) cm?1 of the acetyl methyl group, fine splitting up to 4.9 GHz is found in the spectrum. The conformational structure is not only confirmed by the rotational constants, but also by the orientation of the internal rotor. The 14N quadrupole hyperfine splittings are analyzed and the deduced coupling constants are compared with the calculated values.  相似文献   
10.
建立了液相色谱-四级杆飞行时间串联质谱联用技术同时测定4种甜味剂(安赛蜜、糖精钠、甜蜜素、阿斯巴甜)及2种抗氧化剂(叔丁基对苯二酚、丁基羟基茴香醚)的方法.试验采用Extend-C18色谱柱分离与ESI(-)检测,以乙腈-1 mmol/L乙酸铵为流动相梯度洗脱,在6 min内实现6种目标物的快速分离,检测限为0.250 0~5.00 0 ng/m L,日间精密度小于10.71%(n=3),液态样品平均回收率为83.24%~118.3%.方法准确、灵敏,可快速检测食品中的甜味剂和抗氧化剂.  相似文献   
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