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71.
Determination of rimantadine in pharmaceutical preparations by capillary zone electrophoresis with indirect detection or after derivatization 总被引:2,自引:0,他引:2
Summary Rimantadine is synthetic analog of amantadine; both are antiviral agents used for prophylaxis and treatment of influenza A.
A capillary zone electrophoretic (CZE) procedure for the determination of rimantadine has been developed. As the direct determination
of rimantadine is poorly sensitive because the compound is almost transparent in the UV/Vis range, several indirect methods
were studied. Two were found to be the particularly useful: (a) indirect detection using 5 mM 4-methylbenzylamine in 1:4 methanol-water
as absorbing background electrolyte, with detection at 210 nm, and (b) derivatization of rimantadine with 1,2-naphthoquinone-4-sulfonic
acid in alkaline medium and subsequent determination of the derivative by CZE (40 mM tetraborate, pH 9.2, detection at 280
nm). Uncoated capillary tubing, 44 cm length ×75 μM i.d., was used for both determinations. The detection limits were 0.1
and 2 ppm for methods a and b, respectively. The methods were used to determine rimantadine in pharmaceutical products and
for dissolution testing of Flumadin? tablets. 相似文献
72.
Proficiency testing involves the performance of test procedures on routine samples by a number of laboratories. Interlaboratory proficiency testings provide multiple benefits to participants since they play a key-role in the total quality control of laboratory activities. They serve as a means of self-improving, as a mechanism of continuing education and as a source of information for accreditation agencies. This review highlights basic principles, benefits, criteria and capabilities of a proficiency testing programme for food analysis laboratories as well as their role in the implementation of rapidly developing food control legislation. 相似文献
73.
David W. Holt 《Accreditation and quality assurance》2000,5(9):389-391
This report addresses the proposition: current proficiency testing (PT) schemes for therapeutics and toxicology can easily
engender complacency. The proposition was based on the premise that there are substantial between-laboratory differences and
objectives in the supply of services for the measurement of drugs, as a result of which it is difficult to design PT schemes
which adequately cover the requirements of all laboratories. Thus, acceptable performance in a PT scheme may lead participants
to consider that they have tested their procedures more rigorously than is the case. Four areas, validity of the PT scheme,
PT material, frequency of testing and acceptance criteria are examined.
Received: 15 April 2000 · Accepted: 15 April 2000 相似文献
74.
A simple, cost effective, and yet sensitive sample preparation technique was investigated for determining Polycyclic Aromatic Hydrocarbons (PAHs) in solid samples. The method comprises ultrasonic extraction, Stir Bar Sorptive Extraction (SBSE), and thermal desorption–gas chromatography–mass spectrometry to increase analytical capacity in laboratories. This method required no clean-up, satisfied PAHs recovery, and significantly advances cost performance over conventional extraction methods, such as Soxhlet and Microwave Assisted Extraction (MAE). This study evaluated three operational parameters for ultrasonic extraction: solvent composition, extraction time, and sample load. A standard material, SRM 1649 a (urban dust), was used as the solid sample matrix, and 12 priority PAHs on the US Environmental Protection Agency (US EPA) list were analyzed. Combination of non-polar and polar solvents ameliorated extraction efficiency. Acetone/hexane mixtures of 2:3 and 1:1 (v/v) gave the most satisfactory results: recoveries ranged from 63.3% to 122%. Single composition solvents (methanol, hexane, and dichloromethane) showed fewer recoveries. Comparing 20 min with 60 min sonication, longer sonication diminished extraction efficiencies in general. Furthermore, sample load became a critical factor in certain solvent systems, particularly MeOH. MAE was also compared to the ultrasonic extraction, and results determined that the 20-min ultrasonic extraction using acetone/hexane (2:3, v/v) was as potent as MAE. The SBSE method using 20 mL of 30% alcohol-fortified solution rendered a limit of detection ranging from 1.7 to 32 ng L−1 and a limit of quantitation ranging from 5.8 to 110 ng L−1 for the 16 US EPA PAHs. 相似文献
75.
E. Van Hoeck T. De Schaetzen C. Pacquet F. Bolle L. Boxus J. Van Loco 《Analytica chimica acta》2010,663(1):55-59
Benzophenone (BP) and 4-methylbenzophenone (4MBP) are photo-initiators that are generally used to cure ink on carton boards.In this contribution, a fast and reliable method for the determination of BP and 4MBP in breakfast cereals is described. The sample was extracted ultrasonically using a mixture of dichloromethane and acetonitrile (1:1), followed by a clean-up of the extract using solid phase extraction with a silica cartridge. Finally, the extract was analysed by GC-MSn. Benzophenone-d10 was used as internal standard. The presented method is validated in terms of linearity, recovery, repeatability and intra-laboratory reproducibility, specificity, limit of detection and limit of quantification. In conclusion, this method is able to detect both BP and 4MBP at very low concentrations (LOD = 2 μg kg−1) in breakfast cereals. 相似文献
76.
超声波对制备Co-Fe/硅藻土选择加氢催化剂的影响 总被引:1,自引:0,他引:1
分别在有无超声条件下,采用分步浸渍法制备了负载型Co-Fe/硅藻土催化剂,以肉桂醛选择加氢为肉桂醇为探针反应,在固定床微分反应器上考察了催化剂的活性.采用热分析、红外、XRD及正电子寿命谱等技术分析了催化剂的催化性能及超声波对活性的影响.结果表明,经超声处理的催化剂对肉桂醛加氧为肉桂醇转化率、选择性和收率明显提高.超声处理没有改变催化剂载体的结构,但使主、助催化剂更好地分散在载体上,使催化剂表面的两类缺陷尺寸变小,同时增加第二类缺陷数量,有更好的催化活性. 相似文献
77.
污泥和沉积物中微量大环内酯类、磺胺类抗生素、甲氧苄胺嘧啶和氯霉素的测定 总被引:7,自引:0,他引:7
利用超声波辅助萃取(USE)技术,联合固相萃取(SPE)净化浓缩以及液相色谱-电喷雾串联质谱(LC-ESI-MS/MS)技术,建立了城市污泥和河流底泥中微量-痕量大环内酯类、磺胺类抗生素、甲氧苄胺嘧啶和氯霉素的多目标定量分析方法.样品经USE提取,SPE净化后,用LC-ESI-MS/MS检测.选择C18为分析柱,甲醇、5 mmol/L醋酸铵和0.1%甲酸混合溶液为流动相,选择在ESI正电离源下多反应监测(MRM)模式检测.对比了USE和加速溶剂萃取(ASE)对抗生素的萃取效率,优化了萃取条件.结果表明: USE和ASE对所选抗生素的萃取效率相当; 而50%甲醇溶液在酸性条件下(pH 2)萃取效率最好.抗生素的方法检出限为2.2~66.9 ng/g(干重,下同); 回收率介于74.7%~111.8%之间; 相对标准偏差小于10.6%.应用此方法在广州某污水处理厂脱水污泥及某河涌底泥中检测到磺胺二甲基嘧啶、克拉霉素、脱水红霉素及罗红霉素等多种抗生素,含量为6.8~125.6 ng/g. 相似文献
78.
79.
The ultrasonic degradation of novel propylene based plastomer (DP) melts with different melt viscosities was conducted in a “static” ultrasonic device where the samples were taken from various distances from the tip of an ultrasonic probe. The effects of ultrasonic time, oscillation temperature, ultrasonic intensity and the distance from the ultrasonic probe tip on the degradation behavior of DP melts as well as the ultrasonic degradation effect on the linear rheological behavior of DP melts were studied. The results show that the increase of initial melt viscosity of DP (higher molecular weight) has greater impact on the ultrasonic degradation of DP melt. The molecular weight and intrinsic viscosity of DP decrease with the increase of ultrasonic oscillation time and they approach to a limiting value. The molecular weight distribution of DP increases after ultrasonic degradation. Decreasing oscillation temperature and distance from probe tip and increasing ultrasonic intensity lead to an increase in the degradation of DP melt. The linear rheological behavior measurements of the samples obtained near the ultrasonic probe tip show that ultrasonic oscillations decrease the complex viscosity, zero shear viscosity, viscoelastic moduli, cross modulus, relaxation time and the slope of log G′ − log G″ for DP melts. 相似文献
80.
Ultrasonic oxidation of iodide was investigated in the presence of carbon tetrachloride (CCl4). The ultrasonic oxidation of potassium iodide led to formation of iodine and then I3− in the presence of excess iodide, and the generated I3− shows strong UV absorption with a molar absorptivity of 2.31 × 104 L mol−1 cm−1 at the maximum absorption wavelength of 351 nm. The ultrasonic oxidation of iodide was found to be significantly promoted by a small addition of CCl4, and it was further found that the generation rate was increased with the amount of CCl4 added. This can be used to analyze the level of CCl4 dissolved in aqueous solutions. Under optimum conditions, the concentration of generated iodine (or its absorption at 351 nm) was found to correlated linearly with the concentration of CCl4 in the range of 0.2-50 mg L−1 (detection limit = 0.09 mg L−1, R2 = 0.999). As an alternative indirect spectrophotometric method of CCl4 determination, the proposed method was successfully applied to determine the concentrations of CCl4 in several practical samples, showing merits of being sensitive and simple of operation. 相似文献