全文获取类型
收费全文 | 528篇 |
免费 | 10篇 |
国内免费 | 63篇 |
专业分类
化学 | 563篇 |
综合类 | 2篇 |
物理学 | 36篇 |
出版年
2023年 | 4篇 |
2022年 | 6篇 |
2021年 | 7篇 |
2020年 | 9篇 |
2019年 | 7篇 |
2018年 | 3篇 |
2017年 | 17篇 |
2016年 | 12篇 |
2015年 | 26篇 |
2014年 | 11篇 |
2013年 | 29篇 |
2012年 | 99篇 |
2011年 | 18篇 |
2010年 | 26篇 |
2009年 | 47篇 |
2008年 | 34篇 |
2007年 | 30篇 |
2006年 | 36篇 |
2005年 | 27篇 |
2004年 | 29篇 |
2003年 | 14篇 |
2002年 | 23篇 |
2001年 | 5篇 |
2000年 | 14篇 |
1999年 | 14篇 |
1998年 | 13篇 |
1997年 | 12篇 |
1996年 | 7篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1982年 | 2篇 |
排序方式: 共有601条查询结果,搜索用时 500 毫秒
141.
142.
Here, we describe a new approach for electrochemiluminescence (ECL) assay with Ru(bpy)32+-encapsulated silica nanoparticle (SiO2@Ru) as labels. A water-in-oil (W/O) microemulsion method was employed for one-pot synthesis of SiO2@Ru nanoparticles. The as-synthesized SiO2@Ru nanoparticles have a narrow size distribution, which allows reproducible loading of Ru(bpy)32+ inside the silica shell and of α-fetoprotein antibody (anti-AFP), a model antibody, on the silica surface with glutaraldehyde as linkage. The silica shell effectively prevents leakage of Ru(bpy)32+ into the aqueous solution due to strong electrostatic interaction between the positively charged Ru(bpy)32+ and the negatively charged surface of silica. The porous structure of silica shell allowed the ion to move easily through the pore to exchange energy/electrons with the entrapped Ru(bpy)32+. The as-synthesized SiO2@Ru can be used as a label for ultrasensitive detection of biomarkers through a sandwiched immunoassay process. The calibration range of AFP concentration was 0.05-30 ng mL−1 with linear relation from 0.05 to 20 ng mL−1 and a detection limit of 0.035 ng mL−1 at 3σ. The resulting immunosensors possess high sensitivity and good analytical performance. 相似文献
143.
On the basis of copper-enhanced gold nanoparticle tags as an amplification approach, we introduced, in this paper, magnetic nanoparticles for further improving performance of electrochemical immunoassay by anodic stripping voltammetry (ASV) at a glassy-carbon electrode. Due to the use of antibody-immobilized magnetic nanoparticles, the immunoreaction between antibody and antigen takes place in a homogeneous bulk solution phase. Compared with traditional solid interface reaction, the proposed strategy can provide some advantages such as easy of separation, shorter analytical time, wider linear range, and lower detection limit. It was also successfully applied to HBsAg determination in a linear range of 0.1-1500 ng mL−1 with a detection limit of 87 pg mL−1. The proposed analytical strategy holds good selectivity, sensitivity and repeatability and also great promise for the extended application in the fields of clinical diagnosis, bio-affinity assay and environmental monitoring. 相似文献
144.
In this work an electrochemical immunoassay, based on a direct competitive assay, was developed using magnetic beads as solid phase and carbon screen‐printed arrays as transducers for the detection of sulfonamides in food matrices such as honey. Magnetic beads coated with protein A were modified by immobilisation of specific antibodies and then the competition between the target analyte and the corresponding analyte‐labelled with an enzyme was carried out; after the immunosensing step, beads were captured by a magnet onto the working surfaces of a screen‐printed eight‐electrodes array for a multiple electrochemical detection. Screen‐printed eight‐electrodes arrays were chosen as transducers due to the possibility to repeat multiple analysis and to test different samples simultaneously. Alkaline Phosphatase (AP) was used as enzyme label and Differential Pulse Voltammetry (DPV) as fast electrochemical technique. Calibration curves demonstrate that the developed electrochemical immunoassay was able to detect this class of drugs in standard solutions at low concentrations (ng/mL levels). The short incubation times (25 min) and the fast electrochemical measurement (10 sec) make of these systems a possible alternative to classic ELISA tests. 相似文献
145.
M.L. Sánchez-Martínez 《Analytica chimica acta》2009,636(1):58-2396
A homogeneous aggregation immunoassay involving the use of gold nanoparticles (AuNPs) and light scattering detection is described for soy protein determination in food samples. AuNPs act as enhancers of the precipitate that appears when the antigen-antibody complex is formed. The AuNPs-antibody conjugate has been synthesized by physical adsorption of polyclonal anti-soy protein antibodies onto the surface of commercial AuNPs with a nominal diameter of 20 nm. The direct assay is based on the reaction of the conjugate with soy protein, which reaches the equilibrium in about 10 min, and the measurement of the light scattering intensity at 530 nm, which is proportional to the analyte concentration. The dynamic range of the calibration graph is 0.2-20 μg mL−1 and the detection limit value is 65 ng mL−1. The precision, expressed as relative standard deviation, has been assayed at two different concentrations, 0.2 and 1 μg mL−1, giving values ranging from 4.7 to 5.9%. The interference of other proteins has been assayed. The usefulness of this method has been shown by its application to the analysis of fruit juice and “nonmilk yoghourt” samples. The results obtained with the proposed method are similar to those obtained by using a commercial ELISA kit, but the assay time is significantly shorter and the detection limit was about 10 times lower. A recovery study has been also performed, giving values in the range of 84.0-119.3%. 相似文献
146.
Immunochemical characterisation of structure and allergenicity of peanut 2S albumins using different formats of immunoassays 总被引:1,自引:0,他引:1
Hervé Bernard Marie-Françoise Drumare Blanche Guillon Evelyne Paty Pierre Scheinmann Jean-Michel Wal 《Analytical and bioanalytical chemistry》2009,395(1):139-146
Proteins of the 2S albumin family, such as Ara h2 and Ara h6, are most frequently involved in peanut allergy. We have developed
a reverse enzyme allergo-sorbent test (EAST) in which total serum IgE antibodies are first captured by immobilised anti-human
IgE monoclonal antibodies, and then the binding of the anti-Ara h2 and anti-Ara h6 specific IgE to the corresponding labelled
allergens is measured. This reverse immunoassay was used either as a direct EAST or as an EAST inhibition assay to study the
interactions of whole peanut protein extract and purified Ara h2 and Ara h6 with IgE antibodies from peanut-allergic patients.
Finally, we identified some IgE-binding epitopes on Ara h6 using a format of EAST in which the protein is immobilised in a
particular, well defined, manner through interactions with specific monoclonal antibodies (mAbs) coated on the micro-plates.
The fine specificity of those mAbs has been characterised at the epitope level, and their binding to the allergen thus masks
a known particular epitope and makes it unavailable for recognition by IgE antibodies. The reverse EAST increased the ratio
specific signal/background. It avoids interferences with competitors such as anti-peanut protein IgG antibodies and allows
the study of the specificity and/or affinity of the interactions between IgE antibodies and Ara h2 or Ara h6 with a higher
sensitivity and accuracy than the conventional EAST. The EAST results obtained when the allergens are presented by specific
mAbs suggest that the homologous molecular domain(s) in peanut 2S albumins encompass major IgE epitope(s) and are strongly
involved in peanut allergenicity. 相似文献
147.
Flow-injection immuno-bioassay for interleukin-6 in humans based on gold nanoparticles modified screen-printed graphite electrodes 总被引:3,自引:0,他引:3
A flow-injection electrochemical immunoassay system based on a disposable immunosensor for the determination of interleukin-6 (IL-6) was proposed. The immunosensor was prepared by entrapping horseradish peroxidase (HRP)-labeled IL-6 antibody into gold nanoparticles-modified composite membrane at a screen-printed graphite electrode. With a non-competitive immunoassay format, the immunosensor was inserted in the flow system with an injection of sample, and the injected sample containing IL-6 antigen was produced transparent immunoaffinity reaction with the immobilized HRP-labeled IL-6 antibody. The formed antigen–antibody complex inhibited partly the active center of HRP, and decreased the immobilized HRP to H2O2 reduction. The performance and factors influencing the performance of the immunosensor were investigated. Under optimal conditions, the current change obtained from the labeled HRP relative to thionine–H2O2 system was proportional to the IL-6 concentration in the range of 5–100 ng L−1 with a detection limit of 1.0 ng L−1 (at 3δ). The flow-injection immunoassay system could automatically control the incubation, washing and measurement steps with acceptable reproducibility and good stability. Moreover, the proposed immunosensors were used to analyze IL-6 in human serum specimens. Analytical results of clinical samples show the developed immunoassay has a promising alternative approach for detecting IL-6 in the clinical diagnosis. 相似文献
148.
Analytical approach for monitoring endocrine-disrupting compounds in urban waste water treatment plants 总被引:1,自引:0,他引:1
Roda A Mirasoli M Michelini E Magliulo M Simoni P Guardigli M Curini R Sergi M Marino A 《Analytical and bioanalytical chemistry》2006,385(4):742-752
The presence of endocrine-disrupting compounds in influent and effluent water samples from four waste water treatment plants located in Italy was studied. The estrogen-like activity of the water samples was measured using a chemiluminescent recombinant yeast assay which is based on genetically engineered yeast cells that express the human estrogen receptor. This receptor, once activated, elicits the expression of the reporter gene lac-Z and, consequently, the production of β-galactosidase, which is then measured by chemiluminescence. To control and minimize sample matrix effects, an external control based on a modified yeast strain stably expressing β-galactosidase was developed and also used in the assay. Rapid and sensitive chemiluminescent enzyme immunoassays were also developed and validated for the quantification of 17β-estradiol, estrone, and estriol in waste water samples. Results from both methods were compared with a reference high-performance liquid chromatography and electrospray ionization tandem mass spectrometry (HPLC ESI-MS-MS) method developed for the quantification of natural estrogens. The recombinant yeast assay revealed a significant estrogenic activity in the influent samples, ranging from 80 to 400 pmol/L 17β-estradiol equivalents (EEQ), which was reduced by 70–95 % in the effluent samples. The yeast assay also showed a systematic 20–30 % overestimation of estrogenic activity relative to the HPLC ESI-MS-MS method, suggesting the presence of other compounds in the samples with estrogenic activity. The chemiluminescent enzyme immunoassays showed the presence of estrogens in the influent samples (mean concentrations: 350–450 pmol/L for estrone, 5–100 pmol/L for 17β-estradiol, 25–300 pmol/L for estriol), with significantly lower concentrations detected in the respective effluent samples. The waste water treatment was able to reduce natural estrogen concentrations by 40–95 %, although a high variability was observed. The enzyme immunoassay data correlated well with data obtained by the HPLC ESI-MS-MS method. Although the recombinant yeast assay represents a useful tool for a first-level screening of estrogenic activity due to its simplicity and high analytical throughput, sample matrix effects observed in waste water of industrial origin were found to strongly affect the yeast cells response, even when properly corrected for using the external control, thereby limiting its use to urban waste water. Its integration with chemiluminescent enzyme immunoassays would improve its performance by reducing false negative results, thereby enabling its use in extensive studies monitoring for the presence of endocrine-disrupting compounds in urban treatment plant effluents. 相似文献
149.
A rapid (5.5 min) one-step whole blood C–reactive protein (CRP) magnetic permeability immunoassay utilizing monoclonal antibody
conjugated dextran iron oxide nanoparticles (70 nm) as superparamagnetic labels and mixed fractions (1:1 ratio of 15–40 and
60 μm) of polyclonal anti-CRP conjugated silica microparticles for enhanced sedimentation is described. In this one-step assay
procedure, a whole blood sample (4 μl) is applied to an assay glass vial, containing both antibody conjugates, and mixed for
30 s. The target analyte, CRP, forms a sandwich complex between the conjugated nanoparticles and microparticles, and, subsequently,
the complex sediments under normal gravitation within 5 min to the bottom of the vial. The magnetic permeability increase
of the sediment due to the presence of the complexed superparamagnetic nanoparticles is determined using an inductance-based
transducer. Assayed patient whole blood samples were compared with the Abbott Diagnostics Architect reference method. A strong
linear correlation was observed for the CRP concentration range 0–260 mg/l in whole blood (y=1.001x+0.42, R
2=0.982, n=50). The CRP assay presented showed a limit of detection of 3 mg/l and a total imprecision (coefficient of variation) of
10.5%. On the basis of our observations, we propose a rapid, one-step, CRP assay for near-patient testing. 相似文献
150.
《Analytical letters》2012,45(14):1053-1066
Abstract A liver tissue based electrochemical sensor for hydrogen peroxide has been realized for determination of peroxidase activity in solution. Its behaviour is based on the oxygen electrode and an enzyme catalase largely present in liver tissue. The competition between the two enzymatic reactions based on catalase and peroxidase results in a probe for peroxidase activity determination in the range 5 · 10?3 ? 2.5 · 10?1 U/mL. Digoxin and Insulin, have been determined in standard solution by the living-tissue probe, by using immunoreactions with peroxidase labelled hormones and antibodies fixed on vial wall of a commercial test kit. 相似文献