全文获取类型
收费全文 | 315篇 |
免费 | 25篇 |
国内免费 | 9篇 |
专业分类
化学 | 206篇 |
力学 | 12篇 |
数学 | 63篇 |
物理学 | 68篇 |
出版年
2024年 | 1篇 |
2023年 | 8篇 |
2022年 | 9篇 |
2021年 | 15篇 |
2020年 | 4篇 |
2019年 | 7篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 6篇 |
2014年 | 5篇 |
2013年 | 17篇 |
2012年 | 19篇 |
2011年 | 15篇 |
2010年 | 15篇 |
2009年 | 28篇 |
2008年 | 19篇 |
2007年 | 15篇 |
2006年 | 13篇 |
2005年 | 9篇 |
2004年 | 14篇 |
2003年 | 4篇 |
2002年 | 9篇 |
2001年 | 9篇 |
2000年 | 7篇 |
1999年 | 12篇 |
1998年 | 9篇 |
1997年 | 15篇 |
1996年 | 12篇 |
1995年 | 8篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1982年 | 5篇 |
1979年 | 3篇 |
1976年 | 3篇 |
排序方式: 共有349条查询结果,搜索用时 15 毫秒
1.
Reliable, traceable and comparable measurements provide the rational basis for evaluation of the quality of a result and
the starting point for recognized laboratory accreditation in any national area. Modern medical diagnostics and treatment
involve rapidly rising numbers and types of clinical laboratory measurements, that are reliable. Therefore, the basic principles
to be followed to assure the traceability of clinical measurements as required by the Romanian Laws of Metrology are reviewed.
Main sources affecting the quality of the unbroken chain of calibrations that relate the measurements back to appropriate
measurement standards are discussed. Examples of how to achieve traceable measurements in clinical laboratories are presented.
Details of specific uses of reference materials, measuring instruments and standard measurement methods are also discussed.
Received: 8 January 1998 · Accepted: 21 April 1998 相似文献
2.
James O. Westgard 《Accreditation and quality assurance》2004,10(1-2):10-14
For optimal performance of laboratory tests, testing processes should be designed to provide clinically useful quality and QC procedures should be selected to assure that the necessary clinical quality is achieved in routine production. One important issue is how to define clinical quality. Today’s practice guidelines, quality regulations, and quality standards provide some targets for analytical quality, but they fail to adequately address clinical quality. Target values for precision and accuracy are not the same as clinical quality, though analytical performance certainly contributes to the clinical quality of test results. How can we proceed in our quest to improve quality when there are inconsistencies and inadequacies in the specifications found in practice guidelines, regulations, and standards? Today target values are often being set for the wrong targets. A better approach is possible if we focus on test interpretation guidelines to define clinical quality, then derive specifications for the accuracy and precision that are appropriate for the method, as well the QC rules and numbers of control measurements that are necessary to guarantee the desired quality will be achieved in routine operation of the testing process. 相似文献
3.
Medical laboratories of the public sector as well as of the private sector on the island of Mauritius are preparing for accreditation. The clinical laboratory of the Central Health laboratory of the Ministry of Health and Quality of Life has undergone a pre-assessment by experts of the International Atomic Energy Agency (IAEA) through the aegis of a project targeted to members of the Africa Region. Several shortcomings were identified and respective corrective actions were recommended for implementation within a given time frame. In addition to ensuring the competence of the laboratory, accreditation has various positive aspects such as an increased awareness of the staff to quality and better training opportunities. The pre-assessment exercise has provided a gap analysis, which is an important aspect in the preparation towards accreditation. 相似文献
4.
A flow cell with a radial distribution of four all-solid-state ion selective electrodes (ISEs), or alternatively three ISEs and one reference electrode, was designed and optimized for mass production. The radial distribution of the electrodes reduces the cell volume and is expected to minimize cross-contamination between different electrodes. Two different cell prototypes were developed and tested for all-solid-state K+-ISEs based on a solvent polymeric ion-selective membrane (ISM) and a conducting polymer, poly(3,4-ethylenedioxythiophene), as solid internal contact. In the first prototype, PEDOT was electropolymerized from an aqueous solution of the monomer and the doping ion salt, sodium polystyrenesulfonate (NaPSS). The second prototype employed an aqueous dispersion of PEDOT(PSS) that is commercially available (Baytron P, Bayer AG). Compared to electrochemical synthesis, solution casting of the polymer dispersion was found to be a more advantageous method to deposit the conducting polymer layer aiming at mass production. The resulting prototypes of the flow cell had a small volume (ca. 17-37 μl), which makes them suitable for application in clinical analysis. 相似文献
5.
On September 1, 1992 all testing sites in the United States were required to comply with the Clinical Laboratory Improvement
Amendments of 1988 (CLIA'88). These regulations, based on both total quality management (TQM) and continuous quality improvement
(CQI) principles, reshaped the environment for more than 90% of laboratories. CLIA'88 represented a revolutionary change by
imposing universal, uniform regulations based on test complexity for all sites examining materials derived from the human
body for the purpose of providing information for the diagnosis, prevention, or treatment of disease. CLIA'88 specifies minimum
requirements for personnel, quality control, and proficiency testing (PT). In addition, laboratories are required to follow
manufacturers' directions and comply with other specified good laboratory practices. PT is mandated for most of the frequently
run analyses and quality assurance requirements integrate the principles of CQI as well as TQM into the regulatory process.
Biannual inspection is integral to CLIA'88, however, laboratories can choose other federally approved ("deemed") professional
organizations, such as the Commission on Office Laboratory Accreditation, the College of American Pathologists, or the Joint
Commission on Accreditation of Healthcare Organization, having standards that meet or exceed those of CLIA'88. CLIA'88 has
still not been finalized. This article discusses the impact and changes since CLIA's implementation in 1992.
Received: 5 October 1998 · Accepted: 20 October 1998 相似文献
6.
刘康生 《广东微量元素科学》1998,5(7):59-60
采用自拟的降脂方治疗血胆增高患者63人,并与用月见草油胶丸治疗患者61人比较,前者疗效优于后者,两组有显著性差异。 相似文献
7.
《Arabian Journal of Chemistry》2020,13(1):1198-1228
Vanadate and vanadium compounds exist in many environmental, biological and clinical matrices, and despite the need only limited progress has been made on the analysis of vanadium compounds. The vanadium coordination chemistry of different oxidation states is known, and the result of the characterization and speciation analysis depends on the subsequent chemistry and the methods of analysis. Many studies have used a range of methods for the characterization and determination of metal ions in a variety of materials. One successful technique is high performance liquid chromatography (HPLC) that has been used mainly for measuring total vanadium level and metal speciation. Some cases have been reported where complexes of different oxidation states of vanadium have been separated by HPLC. Specifically reversed phase (RP) HPLC has frequently been used for the measurement of vanadium. Other HPLC methods such as normal phase, anion-exchange, cation-exchange, size exclusion and other RP-HPLC modes such as, ion-pair and micellar have been used to separate selected vanadium compounds. We will present a review that summarizes and critically analyzes the reported methods for analysis of vanadium salts and vanadium compounds in different sample matrices. We will compare various HPLC methods and modes including sample preparation, chelating reagents, mobile phase and detection methods. The comparison will allow us to identify the best analytical HPLC method and mode for measuring vanadium levels and what information such methods provide with regard to speciation and quantitation of the vanadium compounds. 相似文献
8.
Marcelín-Jiménez G Morales-Martínez M Angeles-Moreno AP Mendoza-Morales L 《Biomedical chromatography : BMC》2008,22(10):1143-1148
Pharmacokinetics of diphenidol (DPN) is limited due to the lack of analytical methodology. Here, a micro-assay for DPN quantification was developed, by coupling ultra-performance liquid chromatography with tandem mass spectrometry. The procedure involved plasma precipitation and injection of supernatant into UPLC with an Acquitytrade mark C18 column. Detection was in positive electrospray, following transitions of m/z 310.3 --> 292.3 and m/z 275.3 --> 230.2 for DPN and chlorphenamine (internal standard), respectively. The method was linear with a range of 4-400 ng/mL, and a 2 min run time. This method was applied in a switchability trial, where both formulations of DPN were bioequivalent. 相似文献
9.
Krcmova L Solichova D Melichar B Kasparova M Plisek J Sobotka L Solich P 《Talanta》2011,85(3):1466-1471
A new HPLC method for simultaneous determination of neopterin, creatinine, kynurenine and tryptophan in human serum was developed and validated. Monolithic stationary phase's technology (two monolithic columns RP-18e were connected with guard monolithic cartridge 4.6 mm × 50 mm + 3.0 mm × 100 mm and 4.6 × 10 mm) and special auto sampler for micro titration plates (samples are storage in dark cooled place protected against evaporation) were combined with easy sample preparation step. As mobile phase 15 mmol/L phosphate buffer at pH 4.50 was used. Neopterin and tryptophan were detected using fluorescent detection and kynurenine and creatinine were detected by diode-array detection. This method may be suitable for large sequences of samples in clinical research and routine practice. 相似文献
10.
J. Migdalski B. Bas T. Blaz J. Golimowski A. Lewenstam 《Journal of Solid State Electrochemistry》2009,13(1):149-155
A procedure for an all-plastic electrochemical cell comprising miniaturized planar indicator and reference electrodes is described.
All electrodes are based on conducting polymers, are fully integrated, and contain no internal electrolyte. The reference
microsensors were deposited via electrochemical polymerization from a water solution containing the monomer 3,4-ethylenedioxythiophene
(EDOT) or 1-methylpyrrole (MPy) and a biochemical buffer 3-(N-morpholino) propanesulfonic acid [MOPS], 2-(N-morpholino) ethanesulfonic acid [MES], or 2-hydroxy-5-sulfobenzoic acid [SSA]). Ion-sensitive microelectrodes were prepared
by the deposition of the ion-sensitive membrane solution (Ca2+, K+, and Cl−) directly onto the mediating poly-EDOT (PEDOT), PEDOT–SSA, PEDOT–MES, PEDOT–MOPS, or poly-MPy–MOPS layers. 相似文献