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901.
Silica films with honeycomb-like structure were successfully obtained by emulsion method. Emulsion films prepared by the Dip-Withdrawing
method were dried at 180 °C for 2 h and sintered at 500 °C, the films turned from superhydrophilic to superhydrophobic after
being modified by octyltrimethoxysilane (OTMS) to form a self-assembled monolayer (SAM) with low surface energy. The surface
structures and the thickness of the silica emulsion films were observed by scanning electron microscopy (SEM), and the results
showed that the emulsion method had a similar effect to the phase separation one on producing the honeycomb-like structure
that highly influenced the wettability of solid surface. 相似文献
902.
de Lima CJ Ribeiro EJ Sérvulo EF Resende MM Cardoso VL 《Applied biochemistry and biotechnology》2009,152(1):156-168
Pseudomonas aeruginosa PACL strain, isolated from oil-contaminated soil taken from a lagoon, was used to investigate the efficiency and magnitude
of biosurfactant production, using different waste frying soybean oils, by submerged fermentation in stirred tank reactors
of 6 and 10 l capacities. A complete factorial experimental design was used, with the goal of optimizing the aeration rate
(0.5, 1.0, and 1.5 vvm) and agitation speed (300, 550, and 800 rpm). Aeration was identified as the primary variable affecting
the process, with a maximum rhamnose concentration occurring at an aeration rate of 0.5 vvm. At optimum levels, a maximum
rhamnose concentration of 3.3 g/l, an emulsification index of 100%, and a minimum surface tension of 26.0 dynes/cm were achieved.
Under these conditions, the biosurfactant production derived from using a mixture of waste frying soybean oil (WFSO) as a
carbon source was compared to production when non-used soybean oil (NUSO), or waste soybean oils used to fry specific foods,
were used. NUSO produced the highest level of rhamnolipids, although the waste soybean oils also resulted in biosurfactant
production of 75–90% of the maximum value. Under ideal conditions, the kinetic behavior and the modeling of the rhamnose production,
nutrient consumption, and cellular growth were established. The resulting model predicted data points that corresponded well
to the empirical information. 相似文献
903.
Eric B. Kalman Olivier Sudre Ivan Vlassiouk Zuzanna S. Siwy 《Analytical and bioanalytical chemistry》2009,394(2):413-419
Control of ionic transport through nanoporous systems is a topic of scientific interest for the ability to create new devices
that are applicable for ions and molecules in water solutions. We show the preparation of an ionic transistor based on single
conical nanopores in polymer films with an insulated gold thin film “gate.” By changing the electric potential applied to
the “gate,” the current through the device can be changed from the rectifying behavior of a typical conical nanopore to the
almost linear behavior seen in cylindrical nanopores. The mechanism for this change in transport behavior is thought to be
the enhancement of concentration polarization induced by the gate.
Figure
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
904.
Dongfang Zhang 《Journal of mathematical chemistry》2009,46(2):576-585
The electronic transitions and excited-state fragmentation of hydrogen iodide have been studied within the A-band continuum.
The extinction intensity for the excitations from the ground to the low-lying electronic states are derived by performing
the wave packet simulations of nuclear dynamics in this study. The quantum yields of the spin-excited I* product at the different photon energies are determined as well. The results suggest that the possibility of intersystem
crossing can be neglected. Employing the time-dependent density functional theory (TDDFT), the four highest occupied and the
two lowest unoccupied orbitals of hydrogen iodide have been analyzed, and the transition to the state is found to be most probable in the first absorption band. 相似文献
905.
The morphological transformation process of gold nanorods (Au-NRs) resulting from the reaction between tetracycline and iodine
was monitored by the plasmon resonance absorption (PRA) spectra and the scanning electron microscope (SEM) images. It was
found that iodine could fuse Au-NRs into sphericity with the lower aspect ratio and blue shift of the longitudinal PRA band.
It was found, however, that the presence of tetracycline, since it can react with I2, decreases the effective concentration of I2 and its fusion effect on Au-NRs. As a result, the longitudinal PRA of Au-NRs shifts to longer wavelength linearly with increasing
the concentration of tetracycline. With that, tetracycline can be detected in the range of 5.0×10∮5- 5.0×10−4 mol·L−1, with a limit of determination (LOD) of 2.4×10−6 mol·L−1 (3σ). Most foreign substances in the samples did not interfere in the detection, and tetracycline in the synthetic samples
could be detected with the recovery in the range of 92.8%–107.2%, and RSD lower than 4.3%. The concentration of tetracycline
in milk detected with standard addition method was so low that it accorded with the safety regulation.
Supported by the National Natural Science Foundation of China (Grant Nos. 30570465 and 20425517) 相似文献
906.
Yuzhu Zhao Jizhu Zhou Xiaohui Xu Wenbin Liu Jingying Zhang Minghong Fan Jinben Wang 《Colloid and polymer science》2009,287(2):237-241
We present the synthesis and the characterization of a new class of modified polyacrylamides (MPAM) with the unusual trait
of strong emulsification ability, viscosity enhancement capacity, and significant salt tolerance. Besides, the synthesized
polymers have the peculiar aggregation behaviors in aqueous solution. The synthesis was carried out by polymerizing the monomers
such as acrylamide (AM), acrylic acid (AA), unsaturated amphiphilic functional moieties, and high steric hindrance functional
units. Their aggregation behaviors were investigated by using a scanning electron microscope (SEM). The emulsion, formed by
10 ml of MPAM (with the polymer concentration of 1,000 mg/L) and the 10 ml of crude oil, was very stable, which indicates
that the synthesized polymers have unique emulsification properties. The strong hydrophobic interaction between molecules
and the three-dimensional network formed in aqueous solution were exhibited by the experimental results of steady fluorescence
and SEM experiments. It could be concluded that the performance of polymers for enhanced oil recovery (EOR) can be remarkably
enhanced by introducing functional monomers to polymer backbone, which allows the new class of modified polymers to have more
promising application in enhanced oil recovery. 相似文献
907.
On the basis of the isoelectric point of an enzyme and the doping principle of conducting polymers, choline oxidase was doped
in a polyaniline film to form a biosensor. The amperometric detection of choline is based on the oxidation of the H2O2 enzymatically produced on the choline biosensor. The response current of the biosensor as a function of temperature was determined
from 3 to 40°C. An apparent activation energy of 22.8 kJ·mol−1 was obtained. The biosensor had a wide linear response range from 5 × 10−7 to 1 × 10−4 M choline with a correlation coefficient of 0.9999 and a detection limit of 0.2 μM, and had a high sensitivity of 61.9 mA·M−1·cm−2 at 0.50 V and at pH 8.0. The apparent Michaelis constant and the optimum pH for the immobilized enzyme are 1.4 mM choline
and 8.4, respectively, which are very close to those of choline oxidase in solution. The effect of selected organic compounds
on the response of the choline biosensor was studied. 相似文献
908.
Toshiyuki Osakai Junpei Sawada Hirohisa Nagatani 《Analytical and bioanalytical chemistry》2009,395(4):1055-1061
The spectrofluorometric behavior of a membrane potential-sensitive dye, 1-(3-sulfonatopropyl)-4-[β-{2-(di-N-butylamino)-6-naphthyl}vinyl]pyridinium betaine (di-4-ANEPPS), at the polarized 1,2-dichloroethane/water interface was studied
by means of potential-modulated fluorescence (PMF) spectroscopy. The results, combined with those from cyclic and alternating
current voltammetry, clearly suggested that the dye adsorbed at the interface underwent a reorientation with increasing the
interfacial potential, giving a well-developed PMF response as well as a voltammetric response. In addition to the PMF response,
another PMF response was observed by addition of dilauroyl phosphatidylcholine (DLPC). This additional response was well explained
in terms of a reorientation of di-4-ANEPPS at the interface, which would be induced by the potential-dependent desorption
of DLPC from the interface. Thus, the present study supported the reorientation/solvatochromic mechanism for the membrane
potential-sensitive dye rather than the electrochromic mechanism. 相似文献
909.
A novel amperometric sensor for uric acid based on ordered mesoporous carbon modified pyrolytic graphite electrode was developed.
Uric acid oxidation was easily catalyzed by this electrode in a phosphate buffer solution at pH 7.0, with an anodic potential
decrease about 140 mV compared to bare pyrolytic graphite electrode. The uric acid level was determined by the amperometric
method, at a constant potential of 0.31 mV, the catalytic current of uric acid vs. its concentration showed a good linearity
in the range of 1.0 × 10−6−1.0 × 10−4 mol L−1, with a correlation coefficient of 0.999. The detection limit was 4.0 × 10−7 mol L−1. The proposed method could be effectively used for uric acid amperometric sensing in human urine. 相似文献
910.
Masakuni Tako Takeshi Teruya Yukihiro Tamaki Teruko Konishi 《Colloid and polymer science》2009,287(12):1445-1454
The 1H-nuclear magnetic resonance spectrum showed that the l-rhamnosyl residues of native gellan gum were coinvolved in both a small number of 4C1-pyranose conformations and a large number of 1C4-pyranose conformations, whereas for deacylated polymer, almost of the residues were involved in 4C1-pyranose conformation. The flow curves of native gellan gum showed plastic behavior above 0.2%. The elastic modulus stayed
at a constant value with increase in temperature up to 40 °C, then decreased rapidly. The elastic modulus increased with addition
of CaCl2 (6.8 mM) and stayed constant value with increase in temperature up to 65 °C, then decreased rapidly. The stronger elastic
modulus was observed in deacylated gellan gum with addition of CaCl2. The elastic modulus of native gellan gum showed larger value than that in aqueous solution in the presence of urea (4.0 M).
Intra- and intermolecular associations of native gellan gum molecules in the presence of Ca+2 were proposed. 相似文献