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991.
A surface plasmon resonance (SPR) immunosensor for detection of 2,4-dinitrotoluene (2,4-DNT), which is a signature compound of 2,4,6-trinitrotoluene-related explosives, was developed by using a novel oligo (ethylene glycol) (OEG)-based sensor surface. A rabbit polyclonal antibody against 2,4-DNT (anti-DNPh-KLH-400 antibody) was prepared, and the avidity for 2,4-DNT and recognition capability were investigated by indirect competitive ELISA. The sensor surface was fabricated by immobilizing a 2,4-DNT analog onto an OEG-based self-assembled monolayer formed on a gold surface via an OEG linker. The fabricated surface was characterized by Fourier-transform infrared-refractive absorption spectrometry (FTIR-RAS). The immunosensing of 2,4-DNT is based on the indirect competitive principle, in which the immunoreaction between the anti-DNPh-KLH-400 antibody and 2,4-DNT on the sensor surface was inhibited in the presence of free 2,4-DNT in solution. The limit of detection for the immunosensor, calculated as three times the standard deviation of a blank value, was 20 pg mL−1, and the linear dynamic range was found to be between 1 and 100 ng mL−1. Additionally, the fabricated OEG-based surface effectively prevented non-specific adsorption of proteins, and the specific response to anti-DNPh-KLH-400 antibody was maintained for more than 30 measurement cycles. 相似文献
992.
SnO2 nanocrystalline material was prepared with a sol-gel process and thin films of the nanocrystalline SnO2 were coated on the surface of bent optical fiber cores for gas sensing. The UV/vis absorption spectrometry of the porous SnO2 coating on the surface of the bent optical fiber core exposed to reducing gases was investigated with a fiber optical spectrometric method. The SnO2 film causes optical absorption signal in UV region with peak absorption wavelength at around 320 nm when contacting H2-N2 samples at high temperatures. This SnO2 thin film does not respond to other reducing gases, such as CO, CH4 and other hydrocarbons, at high temperatures within the tested temperature range from 300 °C to 800 °C. The response of the sensing probe is fast (within seconds). Replenishing of the oxygen in tin oxide was demonstrated by switching the gas flow from H2-N2 mixture to pure nitrogen and compressed air. It takes about 20 min for the absorption signal to decrease to the baseline after the gas sample was switched to pure nitrogen, while the absorption signal decreased quickly (in 5 min) to the baseline after switching to compressed air. The adhesion of tin oxide thin films is found to be improved by pre-coating a thin layer of silica gel on the optical fiber. Adhesion increases due to increase interaction of optical fiber surface and the coated silica gel and tin oxide film. Optical absorption spectra of SnO2 coating doped with 5 wt% MoO3 were observed to change and red-shifted from 320 nm to 600 nm. SnO2 thin film promoted with 1 wt% Pt was found to be sensitive to CH4 containing gas. 相似文献
993.
The structure and crystal phase of the nanocrystalline powders of Ni1−xZnxFe2O4 (0 ≤ x ≤ 0.5) mixed ferrite, synthesized by ethylene glycol mediated citrate sol-gel method, were characterized by X-ray diffraction and microstructure by transmission electron microscopy. Further studies by Fourier transform infrared spectroscopy were also conducted. Moreover, DC electrical properties of the prepared nanoparticles were studied by DC conductivity measurements. The response of prepared Ni1−xZnxFe2O4 mixed ferrites to different reducing gases (ethanol, hydrogen sulfide, ammonia, hydrogen and liquefied petroleum gas) was investigated. In particular, Ni0.6Zn0.4Fe2O4 composition exhibited high response to 100 ppm ethanol gas at 300 °C. Incorporation of palladium further improved the response, selectivity and response time of Ni0.6Zn0.4Fe2O4 to ethanol gas with the blue shift in the operating temperature by 25 °C. 相似文献
994.
The paper presents a new method of qualitative identification of gas. It is based on a dynamic response of sensor array with the emphasis on the processing of discrete measurement data. The information needed for identification of test samples is obtained in course of profiling the data from calibration measurements. This operation consists of the following steps: classification of data sets, selection of representative data sets, parameterization of classifiers associated with representative data sets and determination of data records. In our work Discriminant Function Analysis was used for data classification. The information saved in data record describes: the sequential number of discrete measurement, combination of gas sensors in this measurement which are best for classification of calibration samples, and the parameters of associated classifier. They are identifiers of gas class. The procedure of data record determination itself is time consuming. However this operation will be performed only at the stage of the development of the measurement instrument and when its malfunction is diagnosed. The routine use of the instrument will be restricted to gas identification task, which only utilizes the results of profiling.The identification of unknown gas is performed on the base of data records and measurement data obtained for this gas. Data records guide the preparation of data sets, separately for each class of gases. These data sets are used as input of the discriminant functions which have parameter values also indicated by data records. It was shown in the present contribution, that the qualitative identification of nine test gas samples (vapors of ethanol, acetic acid and ethyl acetate in air) with our method was very accurate and fast. 相似文献
995.
QIAN Ying YU Yong-sen LI Qiu-shun WU Si-zhu ZHAO Kai-jun YANG Bai-liang ZHANG Yu-shu . State Key Laboratory on Integrated Optoelectronics College of Electronic Science Engineering . College of Chemistry Jilin University Changchun P. R. China . Electrical Diagnosis Division China-Japan Union Hospital Changchun 《高等学校化学研究》2009,25(5):624-627
A high sensitive long period fiber grating(LPFG) sensor for the detection of nitrite is proposed, which is realized by coating multiple poly(sodium 4-styrensulfonate)(PSS) and poly(diallyldimethylammonium) chloride (PDDA) layers on the fiber grating surface. The sensitivity of this LPFG sensor is maximum when the number of assembled layers is 70. Under this condition, a nitrite concentration of 3×10-3 mol/L, which is lower than the National Food Additive Standard, 4.2×10-3 mol/L, can be distinguished. The s... 相似文献
996.
JingQiang Cui JiangLi Fan XiaoJun Peng ShiGuo Sun GuiCai Chen KeXin Guo 《中国科学B辑(英文版)》2009,52(6):780-785
A new fluorescent sensor (1) for Pb2+ containing a 1,4-dicyano-2,5-bis(styryl)benzene fluorophore and 2-(N,N′-bis(carboxylmethyl))amino-1-carboxylmethoxylbenzene as receptor has been synthesized. The sensor selectively responds to
Pb2+ in the aqueous environment, and brings about similar and significant changes in one- and two-photon excited emission spectra:
λ
max red-shift from 460 (519) to 590 nm. The selective response is pH-independent in a large physiological pH range, and two-photon
action cross section (ϕδ) is 51 GM (1 GM = 1×10−50 cm4·s·photon−1·molecule−1) at 740 nm.
Supported by the National Natural Science Foundation of China (Grant Nos. 20705621 & 20706008), the National Basic Research
Project of China (Grant No. 2009CB724706), the Ministry of Education of China, Changjiang Scholars Innovative Research Team
in University (Grant No. IRT0711) and Cultivation Fund of the Key Scientific and Technical Innovation Project (Grant No. 707016) 相似文献
997.
Jianwei Li Huamei Chen Hai Lin Huakuan Lin 《Journal of photochemistry and photobiology. B, Biology》2009,97(1):18-21
A sensitive colorimetric sensor (1) based on 4,5-dinitrobenzene-1,2-diamine was designed and synthesized. Binding of anions such as AcO−, F− and results in a notable change in the visible region of spectrum (an approximately 90 nm red shift), which can be detected by the ‘naked-eye’. Furthermore, the binding ability was evaluated by UV–vis titration experiments as following: AcO− > F− > Cl−, Br−, I−. The nature of the color change of 1 induced by AcO− was due to the intramolecular charge transfer (ICT) which was confirmed by X-ray crystal structure and 1H NMR titration spectra. 相似文献
998.
A voltammetric sensor for sensitive and specific determination of trans‐resveratrol (RES) were prepared based on immobilization of an RES‐imprinted film on the surface of functionalized Indium Tin Oxide (ITO) electrode, which was modified with γ‐methacyloxypropyl trimethoxysilane (γ‐MPS). Cyclic Voltammetry (CV) was presented to extract RES from the molecularly imprinted polymer film and RES were extracted rapidly and completely. The binding performance of the imprinted electrode with the template RES were investigated using differential pulse voltammetry (DPV). The results showed that the imprinted ITO film can give selective recognition to the template RES over that of structurally analogous molecules. A linear response to RES in the concentration range of 2.0×10?6 M to 2.0×10?5 M was observed with a correlation coefficient of 0.992, and the detection limit of the electrochemical sensor was 8.0×10?7 M. Whereas, binding to the reference nonimprinted electrode, made in the same way but without the addition of template RES, there was almost no response to RES. 相似文献
999.
Silicomolybdate‐doped‐glutaraldehyde‐cross‐linked poly‐L ‐lysine (PLL‐GA‐SiMo) film modified glassy carbon electrode was successfully prepared by means of electrostatically trapping the silicomolybdate anion in PLL‐GA cationic coating. The PLL‐GA‐SiMo film was stable and the charge transport through the film was fast. The modified electrode shows excellent electrocatalytic activity towards bromate reduction with significant reduction of overpotential. In amperometric determination of bromate, the calibration plot was linear over the concentration range of 5×10?5 to 1.2×10?3 M with a sensitivity of 3.6 μA mM?1. Furthermore, PLL‐GA‐SiMo film electrode showed fast response and good stability. 相似文献
1000.
Online analysis of products from a direct ethanol fuel cell 总被引:1,自引:0,他引:1
David D. James Dwayne V. Bennett Guangchun Li Azra Ghumman Robert J. Helleur Peter G. Pickup 《Electrochemistry communications》2009,11(10):1877-1880
Methodology for the online analysis of the main products from a direct ethanol fuel cell (DEFC) has been developed. The liquid exhaust from the fuel cell is first passed through a conductivity cell to determine the concentration of acetic acid and then CO2 is extracted into a nitrogen stream for determination with a flow-through infrared-based CO2 sensor. The other major product, acetaldehyde can be obtained by difference from the current. The continuous measurement of these products allows monitoring of changes in product distributions with time and operating conditions, resulting in a simple online system for rapid evaluation of anode catalysts in DEFCs. 相似文献