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71.
A simple and automated methodology for a sensitive electrochemical detection of enzyme immunoassays that employ alkaline phosphatase (AP) as label has been developed. A flow injection system with programmable pump, valve and cell functions, amperometric detection of indigo and screen-printed electrodes (SPEs) are responsible for the advantages of this methodology. Amperometric detection at a low potential of indigo, the product of the enzymatic hydrolysis of the substrate 3-indoxyl phosphate (IP), is combined with a flow injection system. This incorporates in the flow cell a disposable screen-printed board provided with a graphite working electrode. No electrode pretreatment is necessary to obtain reproducible signals. The system was applied to the determination by an enzyme-linked immunosorbent assays (ELISA) of pneumolysin (PLY), a toxin related to respiratory infections. Linear calibration curves for low and high concentration ranges were obtained. These were also performed in a proteic matrix and linearity was also obtained. 相似文献
72.
Neutron diffraction studies of hydrogen positions in small molecules of biological interest at Trombay have provided valuable
information that has been used in protein and enzyme structure model-building and in developing hydrogen bond potential functions.
The new R-5 reactor is expected to provide higher neutron fluxes and also make possible smallangle neutron scattering studies
of large biomolecules and bio-aggregates. In the last few years infrastructure facilities have also been established for macromolecular
x-ray crystallography research. Meanwhile, the refinement of carbonic hydrases’ and lysozyme structures have been carried
out and interesting results obtained on protein dynamics and structure-function relationships. Some interesting presynaptic
toxin phospholipases have also been taken up for study. 相似文献
73.
V. Slavinska Dz. Sile G. I. Chipens Yu. Balodis G. Rozenthal K. Venteris E. Lukevics 《Chemistry of Heterocyclic Compounds》2003,39(12):1579-1583
A method was developed for the synthesis of N-[1-(S)-(ethoxycarbonyl)-3-phenylpropyl]alanylproline (enalapril) by reductive alkylation of alanylproline with ethyl 2-oxo-4-phenylbutenoate under the conditions of hydrogenation in the presence of palladium black and 1.6% Pd/C. The yield of enalapril amounted to 65%. With the ethyl ester of the -oxo acid the diastereoselectivity of formation of the S,S,S-diastereomer was higher than with the saturated synthon. It is assumed that with ethyl 2-oxo-4-phenylbutenoate as synthon a conformationally restricted surface complex is formed between the unsaturated synthon and the active centers of the catalyst. During reductive alkylation of alanylproline by ethyl 2-oxo-4-(2-thienyl)butenoate poisoning of the catalyst occurs. 相似文献
74.
Atkinson CE Aliev AE Motherwell WB 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(8):1714-1723
A binding site optimisation protocol for the design of artificial enzymes based on "small molecule-small molecule" binding studies by diffusion NMR is presented. Since the reaction chosen was the hydrolysis of ester 1 ([4-(4-carboxy-1-oxobutyl)-aminobenzyl]-phenethyl ester), an analogous phosphonate ester 2 ([4-(4-carboxy-1-oxobutyl)-aminobenzyl]-phosphonic phenethyl ester) was selected as a suitable transition state analogue (TSA). The key objective of the NMR studies was to find a unit with functional groups capable of binding to the acidic sites of the TSA. Nine dipeptides, mainly with basic and hydroxyl groups, were used and their affinity to the TSA was studied by measuring the change in the diffusion coefficient, D(pep), upon binding by pulse field gradient NMR. The value of D(pep) at 298 K in D(2)O at pD 5, 7 and 10 was measured both in free solution, and mixtures containing one dipeptide and the TSA. As both components are low molecular weight species with M < 500, a TSA-to-dipeptide ratio of 10:1 was used to detect significant changes in D(pep). The results revealed that dipeptides with basic residues show higher affinity to the TSA than those with hydroxyl or aliphatic side chains in aqueous solutions. The dipeptide showing the most significant relative change in D(pep) was H-Arg-Arg-OH, and the binding constant was estimated to be 86 L M(-1) by measuring D(pep) at varying concentrations of the TSA. In addition, binding of the TSA to a new water-soluble polymer with a polyallylamine backbone and randomly distributed Arg-Arg binding sites was examined, and the binding constant was estimated to be > or =1500 L M(-1). As confirmed by further catalytic activity tests, polymers containing Arg-Arg as a binding site are capable of significant rate accelerations in the hydrolysis of ester 1. 相似文献
75.
The dynamic behavior of the reaction-diffusion system, composed of glucose oxidase (EC 1.1.3.4) immobilized at a uniform concentration in a membrane, used as a glucose electrode is represented by a diffusion equation with a nonlinear reaction-term in one-dimensional space. The mathematical model is analyzed by computer simulation, that is, numerical integration of the equation under various initial and boundary conditions, to examine the effect of enzyme concentration on the response characteristics (responsiveness and linearity in response) of the electrode. The analysis of the responses of the system to stepwise changes in the boundary value (glucose concentration in simple solution) infers that the enzyme concentration governs the patterns of the spatial distributions of the substrates (glucose and dissolved oxygen) in steady states and transient responses. It is also revealed that the response characteristics of the electrode are optimized with concentration of immobilized enzyme and that the system establishes the steady states at the same spatial distributions of the substrates, regardless of the boundary value. The diffusion of the substrates and the oxygen concentration also have significant effects on the response characteristics of the electrode. 相似文献
76.
Carbon nanotubes used for constructing biosensor was described for the first time. Single-wall carbon nanotubes (SWNTs) functionalized with carboxylic acid groups were used to immobilize glucose oxidase forming a glucose biosensor. The biosensor response can be determined by amperometric method at a low applied potential (0.40V). 相似文献
77.
Summary The use of non-segmented flow, post-column reaction detection is evaluated for use with miniaturized HPLC. Non-segmented open-tubular reactors with internal diameters 0.1 mm to 0.25 mm and packed-bed reactors with internal diameters of 1 mm, filled with 5 and 10 m particles are evaluated theoretically and experimentally with respect to band broadening and pressure drop characteristics. An integrated system consisting of miniaturized HPLC (1 mm i. d.) columns and compatible hardware is described. An example of the separation of catecholamines is given. 相似文献
78.
79.
Biochemistry is a branch subject of chemistry, which is the study of chemical structures and processes associated with living organisms. COVID-19 pandemic is a problem for human beings. From the perspective of biochemistry, this paper demonstrates the chemical structure and interactions of SARS-CoV-2's spike protein and its receptor (human angiotensin converting enzyme 2), and summarizes the related research progresses. The authors hope to provide insights for the development of COVID-19 vaccine. 相似文献
80.
Minoru Isobe Prof. Dr. Masakuni Kurono Dr. Katsunori Tsuboi Dr. Akira Takai Prof. Dr. 《化学:亚洲杂志》2007,2(3):377-385
We have accomplished the synthesis of 13C‐labeled tautomycin at the C18, C19, C21, and C22 positions starting from 100 % [13C]triethylphosphonoacetate for the purpose of elucidating the dynamics and conformation of the C17–C26 moiety. NMR spectroscopy of 13C‐labeled tautomycin revealed strong binding with protein phosphatase type 1 and new features in the 13C NMR spectrum, such as the very small three‐bond coupling constants (2J). 相似文献