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991.
This study proposed a novel technology, which uses exposed technology with ultraviolet light‐emitting‐diode (UV‐LED) arrays and the polydimethylsiloxane (PDMS) magnetic flexible soft mold imprint technology, to develop exposed equipments with UV‐LED arrays. This study used magnetic soft mold imprint technology to replicate the structure of microlens, providing a more effective alternative for imprint technology and application. The measurement results showed that PDMS with magnetic iron powder can precisely cast mold to replicate the structures of microlens. Electromagnetic plates were used to control even imprinting with magnetic force, in order to fill the mold of micro‐structure of the photo‐resist. Magnetic iron powder was added to PDMS to produce composite material, which can effectively avoid the transformation of pure PDMS during soft mold imprinting, and increase mechanical strength. Magnetic PDMS soft mold is easy to make, and the casting time is short, so that costs can be effectively reduced. Also with advantages of less free energy on its surface, and unlikely to adhere to the photo‐resist during imprinting, it can be combined with electromagnetic plates evenly to control the magnetic soft mold. This imprinting technology is a big advantage to the production process of micro‐structures during imprinting. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
992.
This paper provided an easy and flexible method to synthesize high molecular weight polyesters by polycondensation and chain extension. Low molecular weight polybutylene adipate, polybutylene succinate, and poly(butylene succinate‐co‐butylene adipate) (PBSA) were synthesized through melt condensation polymerization from adipic acid and/or succinic acid with butanediol. The prepolyesters obtained had different amount of ? COOH and ? OH terminal groups. Chain extension of them was carried out at 180–240°C using 2,2′‐(1,4‐phenylene)‐bis(2‐oxazoline) and adipoyl biscaprolactamate as combined chain extenders. The influencing factors of the chain extension were studied. At the optimal conditions, chain‐extended polybutylene adipate with Mn up to 39,100, polybutylene succinate with intrinsic viscosity of 0.99 dl/g, and PBSA with intrinsic viscosity from 0.73 to 0.81 dl/g were synthesized. The chain‐extended polyesters were characterized by IR spectrum, 1H NMR spectrum, differential scanning calorimetry, thermogravimetric analysis (TGA), wide angle X‐ray scattering, and tensile test. The thermal analysis showed that chain extension often led to slight decrease of the regularity, the crystallinity, and the melting point. This deterioration of the properties is not harmful enough to impair their thermal properties and obstruct them from being used as biodegradable thermoplastics. The TGA showed that the chain‐extended polyesters were stable with initial decomposition temperature over 354.7°C. The tensile strength of the chain extended PBS and PBSAs with butylene adipate units less than 20 mol% was in the range of 18.95–31.22 MPa. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
993.
Extractive separation, preconcentration, and determination of gold as an ion associate (IA) with 2-[2-(4-methoxyphenylamino)vinyl]-1,3,3-trimethyl-3H-indolium chloride in extracts by spectrophotometry and atomic
absorption spectrometry were studied. The optimal conditions were found for the extraction of IA with aromatic hydrocarbons
and acetate esters. The main chemical analytical properties of the ion associate were determined. The formation of IA enables
extractive separation of gold from Al, Cr, Mn, Fe, Co, Ni, Zn, Cu, Cd, Pt, Hg, Bi, Ag, Pb, and Pd. By varying the volume ratio
of the aqueous and organic phases in the range of (1–40): 1, one can combine extractive separation and the preconcentration
of gold and decrease the detection limit for gold to 0.031 mg/L (extraction-spectrophotometric determination) or 0.084 μg/L
(direct determination in extracts by electrothermal atomic absorption spectrometry). Procedures were developed for the determination
of trace amounts of gold, and their performance characteristics were calculated. 相似文献
994.
E. J. Gao S. H. Liu M. Zhang L. Lin R. S. Wang T. D. Sun Y. Wang Z. Wen 《Russian Journal of Coordination Chemistry》2011,37(4):257-261
A new coordination polymer [Pb(2,2′-Bipy)(NO3)2(H2O)] n has been successfully synthesized and characterized (where 2,2′-Bipy = 2,2′-bipyridine). The crystal structure of the polymer was determined by single-crystal X-ray diffraction, crystallizing in the monoclinic crystal system, space group P21/n with unit cell parameters: a = 7.1673(5), b = 9.8706(6), c = 19.1825(12) Å; β = 90.0780(10)°; V = 1357.08(15) Å3, and Z = 16. The Pb atom was six-coordinated with N(1) and N(2) from 2,2′-Bipy, O(2), O(3), and O(6) in nitrate; O(1) from coordinated water, forming a slightly distorted octahedral geometry. The structure units aggregate together to give birth to the infinite 1D chains via bridged nitrate, and 2D networks and three-dimensional frameworks were obtained through hydrogen bonding and π-π-stacking interaction among aromatic rings, respectively. 相似文献
995.
H. Y. Zhang H. Li G. Liu T. T. Liu F. Yue J. D. Wang 《Russian Journal of Coordination Chemistry》2011,37(11):839-844
One-pot reaction containing Zn(NO3)2, Cd(NO3)2, NH4SCN, and 4-amino-1,2,4-triazole (Atrz) proceeded by refluxing for different periods and gave different products. When the
mixture was refluxed for 1 h, the product was a 1D chain polymer [Cd(Atrz)2(SCN)2]
n
. However, when the refluxing time was increased to 3 h, a novel 3D 3d-3d heterometallic framework complex [Cd2.84Zn2.16(Atrz)6(SCN)10] · 4H2O (I) with 66 topology was obtained. The fluorescent property of I in the solid state was discussed. 相似文献
996.
M. Ayd?nZ. Durmus H. KavasB. Esat H. SözeriA. Baykal F. Y?lmazM.S. Toprak 《Polyhedron》2011,30(6):1120-1126
Poly(3-thiophene acetic acid)/Fe3O4 nanocomposite is synthesized by the precipitation of Fe3O4 in the presence of poly(3-thiophene acetic acid) (P3TAA). Structural, surface, morphological, thermal properties and conductivity characterization/evaluation of the nanocomposite were performed by XRD, FT-IR, TEM, TGA, and conductivity measurements, respectively. The capping of P3TAA around Fe3O4 nanoparticles was confirmed by FT-IR spectroscopy, the interaction being via bridging oxygens of the carboxylate and the nanoparticle surface through bidentate binding. The crystallite and particle size were obtained as 9 ± 2 nm and 11 ± 1 nm from XRD line profile fitting and TEM image analysis, respectively, which reveal nearly single crystalline nature of Fe3O4 nanoparticles. Magnetization measurements reveal that P3TAA coated magnetite particles do not saturate at higher fields. There is no coercivity and remanence revealing superparamagnetic character. Magnetic particle size calculated from the theoretical fitting as 9.1 nm which coincides the values determined from TEM micrographs and XRD line profile fitting. The comparison to the TEM particle size reveals slightly modified magnetically dead nanoparticle surface. 相似文献
997.
Mario Llano-RestrepoAuthor Vitae Y. Mauricio Muñoz-MuñozAuthor Vitae 《Fluid Phase Equilibria》2011,307(1):45-57
Due to the economics of the ethylene market and the subsidized production of fermentation-based ethanol in some countries, use of the ethylene hydration process to make ethanol has been steadily declining. The economics of this process might improve by combining the reaction and separation in a reactive distillation column, whose conceptual design requires a study of the combined chemical and phase equilibrium (CPE) of the reacting system. In this work, the Peng-Robinson-Stryjek-Vera equation of state was combined with the UNIQUAC activity coefficient model through the Wong-Sandler (WS) mixing rules in order to correlate the available experimental data for the vapor-liquid equilibria (VLE) of the ethylene-water, ethylene-ethanol, and ethanol-water binary systems at 200 °C. The interaction energies of the UNIQUAC model and the binary interaction coefficient of the WS mixing rules were used as the fitting parameters. From the optimum values of these parameters, both the VLE and the combined CPE of the ethylene-water-ethanol ternary system were predicted at 200 °C and various pressures. At this temperature, the catalytic activity of a H-pentasil zeolite has already been reported to exhibit a maximum for ethylene hydration, and also the experimentally measured two-phase region of the ternary system is sufficiently wide. By means of the reactive flash method, the chemical equilibrium compositions of the liquid and vapor phases were determined for several pressures, and the equilibrium conversion and the vapor fraction were calculated as functions of the ethylene to water feed mole ratio. It turns out that the vapor-liquid mixed-phase hydration of ethylene achieves equilibrium conversions much higher than those computed for a vapor-phase reaction that would hypothetically occur at the same conditions of pressure and feed mole ratio. It was found that the reactive phase diagram of the ternary system exhibits a critical point at 200 °C and 155 atm. 相似文献
998.
Atmospheric pressure plasma (APP) treatment was applied as a pretreatment process to enhance the deposition of printing paste
in order to improve the final colour properties of digital ink-jet printed cotton fabrics. Three printing pastes containing
natural polymers, i.e. (1) sodium alginate, (2) chitosan and (3) sodium alginate-chitosan mixture, were prepared separately.
After APP treatment, cotton fabric was padded with different printing pastes prior to digital ink-jet printing. Experimental
results showed that APP pretreatment could increase the colour yield of the digital ink-jet printed cotton fabric significantly
even after washing. In addition, other properties such as colour fastness to crocking, colour fastness to laundering, outline
sharpness and anti-bacterial properties were also improved when compared with those of the control cotton fabric printed without
APP pretreatment. However, the influence of printing paste on the colour properties of the digital ink-jet printed cotton
fabrics depended very much on the composition of the printing paste. The scanning electron microscope images evidenced that
the APP treatment could enhance the deposition of printing paste on the cotton fabric surface as proved qualitatively by both
the contact angle and wetting time measurement as well as quantitatively by both the X-ray photoelectron spectroscopy and
carboxyl group/nitrogen content analysis. 相似文献
999.
Chitosans with high degree of polymerization and molecular weight exhibit poor aqueous solubility which is an impediment in
their applicability. The low molecular weight chitosans (LMWCs) and chitooligosaccharides (COSs) can be used to avoid this
hurdle. The development of an efficient process for reducing the molecular weight of chitosan, without altering its chemical
structure, is of great interest to produce tailormade chitosans of varying Degree of Acetylation (DAs) and Degree of Polymerization
(DPs). The production of well-defined COS-mixtures, or even pure COS, is of great interest since these oligosaccharides are
thought to have several interesting bioactivities and applications. For this proper delineation of their characteristics is
needed. Hence it is our attempt to provide an overview of difffernt methods and techniques of their production and characterization.
Several methods viz. depolymerization under the action of reagents, enzymes, high energy impact and combinations thereof have
been employed to get COS by depolymerization of high molecular weight chitosans. Acid hydrolysis (hydrochloric, nitrous, phosphoric
acid, hydrogen fluoride) and oxidative reductive depolymerization (mediated by peroxide, ozone, and persulfate) are important
routes for synthesis of COSs. These oligomers can be produced from chitin or chitosan as a starting material by enzymatic
conversions. For this, numbers of enzymes have been used. Depolymerization under high energy impact and recombinant approaches
are also being tried for production of COSs. LMWC and COS, like parent chitosan, can be used for drug delivery and gene delivery.
The efficient and productive processes are needed for separation of COSs into its components or mixture of defined characters.
The characterization of COS can be carried out by chromatographic and spectroscopic techniques. Importantly COSs display an
array of biological activities as antimicrobial, anticancer/antimetastatic, wound healing acceleration, immunostimulation,
apoptosis induction or inhibiton, antioxidant, enzyme inhibiton, antihyperlipidemic, antidiabetic, chemoprevention, and many
more. A few of the biological actions are reported only sporadically where as some are persistently taken up by the scientific
fraternity to substantiate the claims and propose possible mechanisms of action. However there remains the disagreement of
results on COS activities. The disagreements can arise due to poor and variable reporting of the properties of COS such as
used in the studies as molecular weight, degree of acetylation, molecular weight distribution, and the pattern of N-acetylation
etc. With production of COS of well defined characters it might be possible to understand the modes of actions of COS in better
ways. 相似文献
1000.
In this study, CO2 laser was used for treating cotton fabric to create surface effects which were found to vary with laser process parameters,
i.e. resolution and pixel time. The resolutions used were 40, 50 and 60 dpi while the pixel time used were 100, 110 and 120 μs.
Both physical and chemical properties at the surface of fabrics treated with different combinations of resolution and pixel
time were analysed by the Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy with Attenuated Total
Reflection mode (FTIR-ATR), and X-ray Photoelectron Spectroscopy (XPS). SEM investigation revealed the appearance of various
numbers of pores, cracks and fragments present on the fibre surface after laser treatment. FTIR-ATR spectra showed that the
laser-treated cotton fabric suffered changes in chemical structure with the hydroxyl (–OH) stretching group being oxidised
to carbonyl/carboxyl groups. The XPS analysis revealed a change in surface elemental composition after laser treatment. Furthermore,
the wicking property of the laser-treated cotton fabrics was evaluated. 相似文献