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31.
气相色谱-负化学源质谱联用法测定菊酯类农药 总被引:1,自引:0,他引:1
通过固相萃取-气相色谱-负化学离子源质谱技术建立了11种拟除虫菊酯类农药残留的检测方法,并应用于茶叶农残检测。样品经乙酸乙酯提取后,用串联的活性炭和中性氧化铝固相萃取柱选择性地富集茶叶中待测组分,再由气相色谱-负化学离子源质谱分时段选择离子监测技术进行测定。方法简单快速,一次进样就能得到11种菊酯残留结果;准确度和精密度高,在0.016μg/kg、0.032μg/kg和0.064μg/kg3个添加水平下的回收率在70%~110%之间,CV≤7.4%;选择性好,消除了色素和其它杂质干扰;灵敏度高,检出限低,除了氯菊酯为10μg/kg外,其它菊酯检出限都在μg/∥kg级,七氟菊酯则达到了0.02μg/kg。 相似文献
32.
Chromatography has been an important tool in marine laboratories. Since the 1960s, marine laboratories have been involved in the analysis of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), and brominated flame retardants (BFRs). Column chromatography and liquid chromatography (LC) techniques have been used, mainly in the clean-up phase, while gas chromatography (GC) has been used extensively in the final determination of these contaminants. Developments have been observed from the use of packed GC columns, via capillary columns to the use of heart-cut multi-dimensional GC and comprehensive multi-dimensional GC. The progress made in interlaboratory studies and the availability of certified reference materials are discussed. 相似文献
33.
The determination of organophosphorus and carbamate pesticides was carried out using an amperometric transducer based on a robust, polishable and easily mechinable biocomposite. The biocomposite material contains graphite powder, a non-conducting epoxy resin and acetylcholinesterase. The enzyme retains its bioactivity in the rigid epoxy-graphite matric. Measurements were carried out with acetylhiocholine as a substrate. Thiocholine produced by enzymatic hydrolysis was oxidized electrochemically at 70 mV (vs. Ag/AgCl in pH 7.0 buffered solution with 0.1 M phosphate and 0.1 m KCl). The decrease rate of substrate steady-state current after the addition of pesticide was used for evaluation. The method of construction allows for the repetitive use of the electrode. Simple polishing procedures are used to regenerate the bioactive transducer surface. 相似文献
34.
35.
The CGC analysis of 25 organophosphorus and organonitrogen pesticides was optimized on two different stationary phases, namely a 5% diphenyl dimethyl silicone (SE-54 type) and a 50% diphenyl dimethyl silicone (OV-17 type) by selecting the best temperature program conditions, using computer simulation. 相似文献
36.
Summary Different methods for removing interference by humic substances in the analysis of polar pollutants have been compared in
the analysis of environmental water by solid-phase extraction (SPE) with a chemically modified polymeric resin coupled on-line
to liquid chromatography with UV detection.
The methods were based on the use of chemical reagents. The best method was found to be addition of sodium sulphite to humic-containing
water before SPE. The appropriate amount of sulphite depends on the amount of humic substances dissolved in the sample—for
analysis of 50 mL tap and Ebro river water, respectively, 250 μL and 500 μL 10 % Na2SO3 solution had to be added. In both cases, the recovery values after chemical treatment were similar to those when a Milli-Q-quality
water standard was analysed. 相似文献
37.
Summary A comparison of the official EPA method 515.1 for determination of chlorinated acidic pesticides and a modification of it is illustrated. Extraction of the analytes from water and their determination and quantitation is by gas chromatography-electron capture detection (GC-ECD), liquid chromatography-UV detection and liquid chromatography-particle beam mass spectrometry. Although HPLC-PBMS was found to be less sensitive than the GC-ECD method, it was, nevertheless, more sensitive than HPLC-UV. The modified method is simpler, quicker and allows more accurate determination of pesticides in aqueous samples.Deceased July 31, 1996 相似文献
38.
Traditionally, the application of supercritical fluid chromatography has been limited to compounds of relatively low polarity.
Thus, we report here that one secondary amine and two quaternary amine salts were successfully eluted from a Deltabond Cyano-bonded
silica column with the addition of sodium alkylsulfonate to the methanol-modified, carbon dioxide-based mobile phase. A possible
ion-pairing interaction between the positively charged analytes and the anionic part of the sulfonate additive has been proposed.
In another set of experiments, the three amine salts readily eluted from both Ethyl-pyridine-bonded silica and Amino-bonded
silica phases without the need of additive although the peak shapes were less than desirable. The addition of sulfonate salt
to the mobile phase again sharpened the peaks. In the presence of a mixture of methanol and CO2, we suggest that these stationary phases are positively charged. We describe here also for the first time the employment
of a strong silica-based anion exchange (SAX) column for supercritical fluid separation of cationic species. Two elution mechanisms
were proposed for the three amine salts depending upon whether the ionic additive was incorporated into the mobile phase.
Separation as the ion-pair was proposed with an ionic additive in the mobile phase; whereas separation of the intact amine
salt from the positively charged basic stationary phases was suggested to be operational without the ionic additive. 相似文献
39.
A new analytical method is described for the determination of organochlorine pesticides (OCPs) in sewage sludges using GC-ion trap-MS–MS. In this work, 16 organo-chlorine pesticides (OCPs) listed by the US Environmental Protection Agency (US EPA) as priority pollutants were separated and quantified. Sludge samples from three of Kuwaits wastewater treatment plants (WWTPs) were analyzed for organochlorine pesticides (OCPs). Spiked sludge samples were extracted with a mixture of (1:1 v/v) dichloromethane (DCM)/hexane. The extracts were cleaned on a silica/aluminum oxide column, then transferred to a gel permeation chromatography (GPC) column, before undergoing further silica/aluminum oxide clean-up; the presence of OCPs was then confirmed by GC-ion trap-MS–MS. Three extraction techniques, soxtec, soxhlet, and pressurized liquid extractions were utilized, compared and validated using the spiked sludge samples. The methods were validated in term of accuracy (recovery) and precision (RSD). The method recovery values varyied from 76.1 to 92.9% for the three extraction techniques. 相似文献
40.
In the present study a multi-residue analytical method was developed for monitoring some polar pesticides such as acephate,
methamidophos, carbofuran, isoproturon, dimethoate in water with SPE (solid-phase extraction) and LC–MS–MS. Acetochlor was
taken as surrogate, and alachlor as internal standard. SPE with different types of columns was compared with LLE (liquid-liquid
extraction). Further, the breakthrough volume for different pesticides was determined. The results showed that the selected
pesticides can be determined very sensitively with LC–MS–MS. The minimum detectable quantity (MDQ) for each pesticide was
about 1.0 ng. To date, SPE cartridge studies showed that the Oasis HLB cartridges were suitable for further studies. However,
for Oasis HLB cartridge, different pesticide showed different breakthrough volume. The results showed that for acephate and
methamidophos, the breakthrough volume was about 30 mL of water sample, much less than the breakthrough volume of other pesticides
studied. Because of the higher vapor pressure and higher Henry's constant of methamidophos, dimethoate and carbofuran, much
attention should be paid on their losses in the evaporation step of the experiment. This analytical method can be applied
to determine pesticide contamination in environmental water samples.
Revised: 12 September 2005 and 21 October 2005 相似文献