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61.
Synthesis and healing properties of poly(arylether sulfone)–poly(alkylthioether) multiblock copolymers containing disulfide bonds
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Takayoshi Akiyama Akira Ushio Yoshitaka Itoh Yuya Kawaguchi Kazuya Matsumoto Mitsutoshi Jikei 《Journal of polymer science. Part A, Polymer chemistry》2017,55(21):3545-3553
Thermoplastic elastomers composed of soft and hard segments are important elastic and processable synthetic polymers. The microphase‐separated soft domains show low glass transition temperature and possess sufficient chain mobility at room temperature. In this study, we report the synthesis and healing properties of multiblock copolymers containing disulfide bonds as dynamic covalent bonds. The multiblock copolymers composed of poly(arylether sulfone) and poly(alkylthioether) segments were synthesized by oxidative coupling polymerization of the corresponding thiol‐terminated oligomers. Atomic force microscopy phase images, differential scanning calorimetry, and dynamic mechanical analysis curves indicated the microphase‐separated morphology of the multiblock copolymer. Self‐healing properties of the polymer were evaluated by changes in the elongation at break of the cut/adhered samples. The elongation recovery increased with UV irradiation time, and the multiblock copolymer showed a 93% recovery after UV irradiation for 5 h. The healing efficiency induced by UV irradiation, determined by subtracting the recovery without UV irradiation, was calculated to be 51%. According to the UV spectra and solubility changes after UV irradiation, the main healing factor in this study was the crosslinking reactions caused by thiyl radicals generated from UV irradiation instead of disulfide exchange reactions. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3545–3553 相似文献
62.
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64.
Simultaneous measurements of velocity and temperature fluctuations in thermal boundary layer in a drag-reducing surfactant solution flow 总被引:6,自引:0,他引:6
The mechanism of turbulent heat transfer in the thermal boundary layer developing in the channel flow of a drag-reducing surfactant solution was studied experimentally. A two-component laser Doppler velocimetry and a fine-wire thermocouple probe were used to measure the velocity and temperature fluctuations simultaneously. Two layers of thermal field were found: a high heat resistance layer with a high temperature gradient, and a layer with a small or even zero temperature gradient. The peak value of
was larger for the flow with the drag-reducing additives than for the Newtonian flow, and the peak location was away from the wall. The profile of
was depressed in a similar manner to the depression of the profile of
in the flow of the surfactant solution, i.e., decorrelation between v and compared with decorrelation between u and v. The depression of the Reynolds shear stress resulted in drag reduction; similarly, it was conjectured that the heat transfer reduction is due to the decrease in the turbulent heat flux in the wall-normal direction for a flow with drag-reducing surfactant additives.List of symbols
ensemble averaged value
- (·)+
normalized by the inner wall variables
- (·)
root-mean-square value
-
C
concentration of cetyltrimethyl ammonium chloride (CTAC) solution
-
c
p
heat capacity
-
D
hydraulic diameter
-
f
friction factor
-
H
channel height
-
h
heat transfer coefficient
-
j
H
Colburn factor
-
l
length
-
Nu
Nusselt number, h
-
Pr
Prandtl number, c
p/
-
q
w
wall heated flux
-
Re
Reynolds number, U
b/
-
T
temperature
-
T
b
bulk temperature
-
T
i
inlet temperature
-
T
w
wall temperature
-
T
friction temperature, q
w
/c
p
u
-
U
local time-mean streamwise velocity
-
U
1
velocity signals from BSA1
-
U
2
velocity signals from BSA2
-
U
b
bulk velocity
-
u
streamwise velocity fluctuation
-
u1
velocity in abscissa direction in transformed coordinates
-
u
friction velocity,
-
v
wall-normal velocity fluctuation
-
v1
velocity in ordinate direction in transformed coordinates
- var(·)
variance
-
x
streamwise direction
-
y
wall-normal direction
-
z
spanwise direction
-
j
junction diameter of fine-wire TC
-
w
wire diameter of fine-wire TC
-
angle of principal axis of joint probability function p(u,v)
-
f
heat conduction of fluid
-
w
heat conduction of wire of fine-wire TC
-
kinematic viscosity
-
local time-mean temperature difference, T
w
–T
-
temperature fluctuation
-
standard deviation
-
density
-
w
wall shear stress 相似文献
65.
Genta Kawaguchi Prof. Dr. Mitsuhiko Maesato Dr. Tokutaro Komatsu Prof. Dr. Hiroshi Kitagawa Prof. Dr. Tatsuro Imakubo Dr. Andhika Kiswandhi Dr. David Graf Prof. Dr. James S. Brooks 《Angewandte Chemie (International ed. in English)》2015,54(35):10169-10172
Simultaneous manipulation of both spin and charge is a crucial issue in magnetic conductors. We report on a strong correlation between magnetism and conductivity in the iodine‐bonded molecular conductor (DIETSe)2FeBr2Cl2 [DIETSe=diiodo(ethylenedithio)tetraselenafulvalene], which is the first molecular conductor showing a large hysteresis in both magnetic moment and magnetoresistance associated with a spin‐flop transition. Utilizing a mixed‐anion approach and iodine bonding interactions, we tailored a molecular conductor with random exchange interactions exhibiting unforeseen physical properties. 相似文献
66.
Surface dilational moduli of polymer monolayers, blended polymer monolayers, and polymer particle monolayers spread at air–water interfaces are reviewed, focusing on measurements using surface pressure isotherm, surface pressure relaxation, and oscillating barrier methods. Differences between the surface dilational moduli of condensed polymer monolayers and expanded polymer monolayers are explored. Moreover, the features of the surface dilational moduli in blended polymer monolayers are discussed in terms of their miscibility. 相似文献
67.
Bani-Yaseen AD Kawaguchi T Price AK Culbertson CT Jankowiak R 《Analytical and bioanalytical chemistry》2011,399(1):519-524
Catechol estrogen-derived DNA adducts are formed as a result of the reaction of catechol estrogen metabolites (e.g., catechol
estrogen quinones) with DNA to form depurinating adducts. Developing a new methodology for the detection of various DNA adducts
is essential for medical diagnostics, and to this end, we demonstrate the applicability of on-chip capillary electrophoresis
with an integrated electrochemical system for the separation and amperometric detection of various catechol estrogen-derived
DNA adducts. A hybrid PDMS/glass microchip with in-channel amperometric detection interfaced with in situ palladium decoupler
is utilized and presented. The influence of buffer additives along with the effect of the separation voltage on the resolving
power of the microchip is discussed. Calibration plots were constructed in the range 0.4–10 μM with r
2 ≥ 0.999, and detection limits in the attomole range are reported. These results suggest that on-chip analysis is applicable
for analyzing various DNA adducts as potential biomarkers for future medical diagnostics. 相似文献
68.
Preparation of carbon quantum dots with tunable photoluminescence by rapid laser passivation in ordinary organic solvents 总被引:2,自引:0,他引:2
Li X Wang H Shimizu Y Pyatenko A Kawaguchi K Koshizaki N 《Chemical communications (Cambridge, England)》2011,47(3):932-934
A simple approach to prepare carbon quantum dots is presented in this communication by laser rapid passivation of nano carbon particles in ordinary organic solvent. The as-prepared carbon dots exhibited visible, tunable and stable photoluminescence (PL). XPS analysis showed that the increased oxygen concentration might be concerned with the origin of PL. 相似文献
69.
Monodisperse, reactive hydrogel microspheres were prepared by precipitation polymerization ofp-nitrophenyl acrylate (NPA) with acrylamide, methacrylic acid, and methylenebisacrylamide in ethanol. The size of microspheres was controlled by the monomer ratio. Some fraction of reactive ester decomposed during the polymerization. The reactive hydrogel microspheres were converted to amphoteric ones by the reaction of NPA units with diamine. The isoelectric point of the amphoteric microspheres was around 4.0, but it was different from the pH at which the microspheres have the minimum size or the most shrunken state. This was attributed to the uneven distribution of induced amine groups. 相似文献
70.