全文获取类型
收费全文 | 484篇 |
免费 | 1篇 |
国内免费 | 113篇 |
专业分类
化学 | 512篇 |
力学 | 18篇 |
数学 | 1篇 |
物理学 | 67篇 |
出版年
2024年 | 1篇 |
2023年 | 17篇 |
2022年 | 13篇 |
2021年 | 11篇 |
2020年 | 14篇 |
2019年 | 10篇 |
2018年 | 12篇 |
2017年 | 12篇 |
2016年 | 11篇 |
2015年 | 10篇 |
2014年 | 13篇 |
2013年 | 44篇 |
2012年 | 23篇 |
2011年 | 14篇 |
2010年 | 13篇 |
2009年 | 36篇 |
2008年 | 31篇 |
2007年 | 31篇 |
2006年 | 41篇 |
2005年 | 21篇 |
2004年 | 36篇 |
2003年 | 21篇 |
2002年 | 20篇 |
2001年 | 19篇 |
2000年 | 20篇 |
1999年 | 28篇 |
1998年 | 15篇 |
1997年 | 8篇 |
1996年 | 10篇 |
1995年 | 7篇 |
1994年 | 6篇 |
1993年 | 9篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1982年 | 2篇 |
1979年 | 1篇 |
排序方式: 共有598条查询结果,搜索用时 375 毫秒
61.
The esterification of octanoic acid with octanol in microemulsion and emulsion system is studied. In the presence of 5–10% dodecylbenzene-sulfonic acid (DBSA), which is a surfactant-type catalyst, high conversion of esterification can be given both in microemulsion and in emulsion system. Compared with emulsion system, single-phase microemulsion is a more effective reaction system for esterification, with the advantages of comparatively little influence by the amount of water, no need of hard stirring, and stable state when laid long. The esterification of other fatty acids and alcohols in this reaction system were also accomplished in favorable conversion. 相似文献
62.
A silicone acr3,1ate micro-emulsion of multipolymer was prepared by seed emulsion polymeri.Tation. The effects of polymerization process, emulsifier rate and amount, initiator rate and amounl, polymerization temperalure, functional monomers, titration time on performances of emulsion have been discussed in detail. 相似文献
63.
In seeded emulsion polymerization, during the second stage, new interfaces appear and the surface area changes. A thermodynamic equilibrium approach is presented which predicts particle morphology of a whole range of non-spherical particles upon polymer conversion. Simulation takes into account swelling ratio, molar volumes and interfacial tension. As the particle geometry is complex, a new mathematical procedure is detailed.The computed data are useful to discuss either the stability or the instability of the particles morphology. These results must be compared with actual experimental structures.Abreviations and symbols G
Gibbs' free energy
-
reduced Gibbs' free energy
- i
interfacial tension
- 12
interfacial tension between polymer 1 and polymer 2
- 1w
interfacial tension between polymer 1 and water
- 2w
interfacial tension between polymer 2 and water
-
r
1
polymer 1 swollen by monomer 2 sphere radius
-
r
2
polymer 2 swollen by monomer 2 sphere radius
-
r
i
interfacial radius
-
h
1
sphere 1 distance to minimal section
-
h
2
sphere 2 distance to minimal section
-
h
i
interfacial sphere distance to minimal section
-
sign ofh
i, positive when the interface sphere is on the side of the sphere 2, negative when the interface sphere is on the side of the sphere 1
-
A
12
surface between polymer 1 and polymer 2
-
A
1w
surface between polymer 1 and water
-
A
1w
0
surface between polymer 1 and water before polymerization
-
A
2w
surface between polymer 2 and water
-
v
1
volume of the polymer 1 swollen by monomer 2
-
v
i
volume of the polymer 1 swollen by monomer 2 before polymerization
-
v
2
volume of the polymer 2 swollen by monomer 2
-
V
p1
polymer 1 molar volume
-
V
p2
polymer 2 molar volume
-
V
m2
monomer 2 molar volume
-
n
p2
polymer 2 number of mole
-
n
p1
polymer 1 number of moles
-
n
m21
monomer 2 number of mole in the swollen polymer 1
-
n
m22
monomer 2 number of mole in the swollen polymer 2
-
n
m2
monomer 2 total number of mole
-
n
m2
monomer 2 number of mole before polymerization
-
TGn
1
polymer 1 swelling rate
-
TGn
2
polymer 2 swelling rate
-
TGn
i
maximum number of mole of monomer 2 in polymeri by mole of polymeri
-
x
polymer 2 conversion rate
-
K, p, q
mathematical variables
-
D, r, a
mathematical variables 相似文献
64.
Amino-functionalized latex particles were obtained batchwise by emulsion copolymerization of styrene and vinylbenzylamine hydrochloride (VBAH) in the presence of 2-2-Azobis(2-amidinopropane) HCl (V50). Size monodispersity of the particles was improved by using divinylbenzene (DVB) as a third monomer at a 2% molar ratio. Surface amino group titration was performed spectrometrically with N-succinimidyl 3-(2 pyridyldithio)propionate (SPDP). The yields of functional monomer incorporation were up to 85%. 相似文献
65.
66.
Mosto Bousmina 《Rheologica Acta》1999,38(1):73-83
Kerner's model for flow of composite elastic media is extended to an emulsion of viscoelastic phases with interfacial tension
undergoing deformations of small amplitude. A privileged internal structure inside the suspended drops is discussed in terms
of fluid circulation across the interface. It is shown that for usual drop radius and interfacial tension values of emulsions,
the rheological behavior predicted by the model, with very simple expression for the complex shear modulus, is quantitatively
similar to that predicted by Palierne's model. Predictions of the model are compared with experimental data obtained on a
polystyrene/polyethylene blend sheared in a small-amplitude oscillatory mode.
Received: 10 August 1998 Accepted: 18 December 1998 相似文献
67.
68.
An emulsion chamber was used to study the characteristics of high energy nuclear interactions from the production spectra
ofγ-rays. The emulsion chamber, which comprised of two parts, namely the detector and the graphite producer unit, was exposed
to cosmic rays for about 7 hr at an atmospheric depth of 10 g cm−2 at Hyderabad (geomagnetic latitude 7·6°N). 720 electromagnetic cascades due toγ-rays were recorded in the detector. These cascades were classified into three groups; (a)γ-rays from nuclear interactions in the detector (b)γ-rays from nuclear interactions in the producer unit and (c)γ-rays of atmospheric origin. The energies of the cascades were determined using photometric method. The spectra ofγ-rays from groups (a) and (c) were determined and compared with similar spectra obtained at greater atmospheric depths. The
spectra were found to obey a power law. The spectrum ofγ-rays of atmospheric origin was found to steepen at high energies,E
r>2200 GeV. 相似文献
69.
Takuji?OkayaEmail author Kenji?Kikuchi Atsushi?Suzuki Chika?Ohara 《Colloid and polymer science》2004,283(1):111-116
An emulsion of poly(methyl methacrylate) (PMMA) was prepared using poly(vinyl alcohol) (PVA) of low degree of hydrolysis with a cloud point as a protective colloid. The behaviour of an aqueous solution of PVA with 80% degree of hydrolysis was first investigated in terms of the Huggins constant in viscometry. MMA was polymerized using the PVA at 20 °C, where no abnormality in the aqueous PVA was observed. The change in transmittance of the emulsion observed with a UV–vis photometer revealed that in the case of UV light of wavelength 370 nm, the transmittance decreased markedly at around 30 °C with an increase in temperature, and then increased with a decrease in temperature. The thermosensitive property resulted from PVA with a low degree of hydrolysis with a cloud point, at a higher temperature of which the PVA loses solubility in water owing to weakening of the hydrogen bond between PVA molecules and water. 相似文献
70.
嵌段共聚物在乳液聚合和分散聚合中的应用 总被引:4,自引:0,他引:4
综述了嵌段共聚物在乳液聚合和分散聚合中作为稳定剂应用的进展,主要讨论了共聚物化学组成,比例,分子量,浓度以及胶束形成等因素对聚合体系的影响。 相似文献