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991.
Electrochemical studies of 1,5-dihydroxynaphthalene as substrate for voltammetric enzyme immunoassay
JIAO Kui YAO Hong XU Jin & ZHANG Shusheng College of Chemistry Molecular Engineering Qingdao University of Science Technology Qingdao China 《中国科学B辑(英文版)》2004,47(3):184-191
Immunoassay is one of the biochemical analytical techniques using the specific antigen antibody com-plexation for analytical purposes. It has extensive ap-plication in clinical diagnostics, prevention and cure of diseases, and virus diagnostics. The presentation and progress of immunoassay methodology are one of the greatest achievements of bioanalytical chemistry. It is estimated that several-hundred millions of immuno-analytical determinations are carried out every year all over the world. E… 相似文献
992.
Yun-Chin Chung Alan Bakalinsky Michael H. Penner 《Applied biochemistry and biotechnology》1997,66(3):249-262
A direct method for determining the cellulose content of biomass residues resulting from simultaneous saccharifiaction and
fermentation (SSF) experiment has been developed and evaluated. The method improves on classical cellulose assays by incorporating
the enzymatic removal of yeast glucans from the biomass residue prior to acid hydrolysis and subsequent quantification of
cellulose-derived glucose. An appropriate cellulasefree, commercially available, yeast-lysing enzyme preparation fromCytophaga was identified. A freeze-drying step was identified as necessary to render the SSF yeast cells susceptible to enzymatic lysis.
The method was applied to the analysis of cellulose and yeast-associated glucans in SSF residues from three pretreated feedstocks;
hybrid poplar, switchgrass, and cornstover. Cellulose assays employing the lysing-enzyme preparation demonstrated relative
errors up to 7.2% when yeast-associated glucans were not removed prior to analysis of SSF residues. Enzymatic lysis of SSF
yeast cells may be viewed as a general preparatory procedure to be used prior to subsequent chemical and physical analysis
of SSF residues.
Oregon State University Agricultural Experiment Station Technical Publication Number 10977. 相似文献
993.
Noncompetitive enzyme immunoassay for α-fetroprotein using flow injection chemiluminescence 总被引:1,自引:0,他引:1
A novel, direct noncompetitive flow injection enzyme immunoassay for α-fetoprotein (AFP) was developed by enhanced chemiluminescence
detection. The method was based on off-line incubation of AFP and horseradish peroxidase (HRP)-labeled anti-AFP, and then
trapping of the unbound enzyme conjugate by an immunoaffinity column filled with AFP-modified Sepharose. The immunocomplex
formed in incubation passed through the column and then was directly detected by a postcolumn chemiluminescence technique.
The optimal conditions for the immunoassay procedure and chemiluminescence detection were established. At a 1:10 dilution
of enzyme conjugate solution, the linear range for chemiluminescence detection of AFP was from 2.0 to 75 ng/mL with a correlation
coefficient of 0.993 and a coefficient of variation of 2.67% at 30 ng/mL. The detection limit was 0.5 ng/mL. This method was
flexible, sensitive, and rapid. The immunoaffinity column of 200 μL could be repeatedly used 100 times without a single decrease.
The whole assay time including the preincubation step was only 30 min for one sample. 相似文献
994.
Glutathione reductase was purified from chicken liver and some characteristics of the enzyme were investigated. The purification
procedure was composed of four steps: preparation of homogenate, ammonium sulfate precipitation, 2′,5′-ADP Sepharose 4B affinity
chromatography, and Sephadex G-200 gel filtration chromatography. Owing to the four consecutive procedures, the enzyme was
purified 1714-fold, with a yield of 38%. Specific activity at the final step was 120 enzyme unit (EU)/mg of protein. The purified
enzyme showed a single band on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The molecular weight
of the enzyme was found to be 100 kDa by Sephadex G-200 gel filtration chromatography, and the subunit molecular weight was
found to be 43 kDa by SDS-PAGE. Optimum pH, stable pH, optimum ionic strength, and optimum temperature were 7.0, 7.4, 0.75
M Tris-HCl buffer including 1 mM EDTA, and 50°C, respectively. K
M and V
max values for NADPH and glutathione disulfide (GSSG) substrates were also determined for the enzyme. 相似文献
995.
Lactobacillus bulgaricus was immobilized in the shell side of an industrial hollow-fiber ultrafiltration module. Acid whey permeate, containing 46
g/L lactose supplemented with 10 g/L yeast extract, was pumped through the tube side at dilution rates of 0.2–2.5/h. At a
cell concentration of 100 g/L, productivity was 1.5–5 g lactic acid/L/h. 相似文献
996.
Comparative Study of Polymeric Supports as the Base of Immobilisation of Chemically Modified Enzymes
One of the difficulties in using optical biosensors based on enzymatic reactions is the immobilisation of the enzyme involved
in the determination. A detailed study has been carried out of the various polymeric supports which could provide a potential
alternative for the immobilisation of chemically modified enzymes. Before immobilisation, the enzyme is attached by means
of a covalent bond to a fluorescent probe, which is optically active in the visible region. The main advantage of this covalent
bond is that it is possible to follow the enzymatic reaction by fluorescence without the need for immobilising any further
reagent (reagentless biosensors). The results indicate that the most stable and reproducible polymeric supports are derived
from polyacrylamide obtained by UV photopolymerisation. The experiments have been carried out using chemically modified glucose
oxidase as the model enzyme. The films thus obtained have a lifetime of at least two months, an RSD of 9.2%, and a linear
range of 300 to 2000 mg L−1 of glucose. They are completely reversible by regeneration in an appropriate buffer solution. 相似文献
997.
The kinetics of free glucose-6-phosphate dehydrogenase (G-6-PDH), biotinylated G-6-PDH, and biotinylated G-6-PDH complexed
with avidin were investigated. The kinetics of the free enzyme were consistent with a sequential rather than a ping-pong mechanism.
The kinetics of the biotinylated enzyme were similar to that of the free enzyme, but the kinetic constants were different;
theK
m value for NADP was halved, whereas theK
m for G-6-P decreased only slightly. In the presence of avidin, theK
m of biotinylated G-6-PDH for G-6-P nearly doubled whereas theK
m for NADP did not change significantly. Avidin complexed with biotinylated G-6-PDH inhibited the enzyme from acting. Based
upon these reactions, it was possible to devise assays for either free biotin or free avidin using biotinylated G-6-PDH as
the indicator enzyme. Concentrations of biotin between 40 and 60 mg/mL, or of 25–95 Μg/mL of avidin could be measured within
2 min through the use of biotinylated G-6-PDH. 相似文献
998.
Michelle Matos de Souza Janaina Heberle Bortoluzzi Eduardo Carasek 《Mikrochimica acta》2006,155(3-4):465-469
The efficiency of a glass-ceramic rod as a base for the preparation of SPME fibers using thermal immobilization was investigated.
Glass-ceramic and fused silica rods were thermally immobilized with poly(butylacrylate) and their absorption capacity was
compared. The absorption capacity between the fiber obtained for thermal immobilization of poly(butylacrylate) on glass-ceramic
surface and commercially PA fiber was also compared. In this study the target analytes were phthalate esters and phenols.
The results obtained for extraction of phenols from aqueous solutions using the headspace mode demonstrated the superiority
of glass-ceramic in relation the silica gel rod as a base for SPME fiber. The direct SPME extraction of phthalate esters from
aqueous solutions using commercial PA fiber and that obtained for thermal immobilization of poly(butylacrylate) on glass-ceramic
rod presented similar results. The repeatability and the reproducibility among extractions using fibers developed in our laboratory
were achieved. 相似文献
999.
Cosnier S 《Analytical and bioanalytical chemistry》2003,377(3):507-520
Electropolymerized films have received considerable attention in the development of biosensors and biochips, and are advancing rapidly. This paper reviews recent advances and scientific progress in electrochemical immobilization procedures for biological macromolecules on electrodes via electrogenerated polymer films. Biomolecule immobilization is classified as covalent linkage, attachment by affinity interactions, and physical entrapment. The last approach entails the use of conducting and non-conducting films, composite polymer films, and templates for the electropolymerization process. Some advances in the electrochemical transduction of biological events (enzymatic reaction, immunoreaction, or oligonucleotide hybridization) involving the redox properties or the conductivity of electropolymerized films are also presented. 相似文献
1000.
氯化血红素作为模拟酶荧光免疫分析乙肝表面抗原 总被引:2,自引:0,他引:2
乙肝表面抗原的测定在临床诊断上是一项很重要的指标.现在一般采用酶联吸附免疫分析技术测定,但是酶本身性质不稳定且价格昂贵、操作繁琐;更重要的是大分子的酶作为标记物,由于空间位阻效应而阻碍抗原-抗体的免疫反应.所以,用小分子催化剂代替大分子酶的研究显得日益重要[1,2].近年来有关模拟酶在免疫分析中的应用已有报道[3,4].本文提出了以氯化血红素作为辣根过氧化物酶(HRP)的模拟酶来标记抗体,以盐酸硫胺素(维生素B1)作为供氢体,成功地实现了乙肝表面抗原(HBsAg)的夹心法荧光免疫分析.测定范围是2.5~500ng/wel… 相似文献