全文获取类型
收费全文 | 1751篇 |
免费 | 41篇 |
国内免费 | 3篇 |
专业分类
化学 | 1417篇 |
晶体学 | 16篇 |
力学 | 10篇 |
数学 | 26篇 |
物理学 | 326篇 |
出版年
2022年 | 11篇 |
2021年 | 7篇 |
2020年 | 7篇 |
2019年 | 26篇 |
2018年 | 12篇 |
2017年 | 12篇 |
2016年 | 24篇 |
2015年 | 20篇 |
2014年 | 41篇 |
2013年 | 94篇 |
2012年 | 84篇 |
2011年 | 95篇 |
2010年 | 54篇 |
2009年 | 45篇 |
2008年 | 87篇 |
2007年 | 79篇 |
2006年 | 76篇 |
2005年 | 94篇 |
2004年 | 76篇 |
2003年 | 62篇 |
2002年 | 59篇 |
2001年 | 62篇 |
2000年 | 64篇 |
1999年 | 35篇 |
1998年 | 29篇 |
1997年 | 32篇 |
1996年 | 29篇 |
1995年 | 21篇 |
1994年 | 34篇 |
1993年 | 36篇 |
1992年 | 42篇 |
1991年 | 29篇 |
1990年 | 20篇 |
1989年 | 27篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 11篇 |
1985年 | 29篇 |
1984年 | 28篇 |
1983年 | 28篇 |
1982年 | 15篇 |
1981年 | 17篇 |
1980年 | 17篇 |
1979年 | 24篇 |
1978年 | 19篇 |
1977年 | 11篇 |
1976年 | 15篇 |
1975年 | 9篇 |
1974年 | 9篇 |
1973年 | 4篇 |
排序方式: 共有1795条查询结果,搜索用时 15 毫秒
91.
Takehito Dei Kazuhide Morino Atsushi Sudo Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2012,50(13):2619-2625
Novel copolymers composed of a styrene (St) derivative bearing a vicinal tricarbonyl moiety and various vinyl monomers such as St, methyl methacrylate (MMA), and N‐vinylpyrrolidone (NVP) were synthesized by (1) radical copolymerization of a St derivative with a 1,3‐diketone structure with St, MMA, and NVP and (2) successive oxidation of the resulting copolymers with N‐bromosuccinimide in DMSO to convert their 1,3‐diketone moieties in the side chains into the corresponding vicinal tricarbonyl moieties. Their tricarbonyl moieties were readily hydrated in water‐containing acetone to generate the corresponding copolymers bearing geminal diol structures in the side chains. On the other hand, heating the resulting copolymers bearing the geminal diol structures in vacuo‐enabled successful recovery of the vicinal tricarbonyl moieties to demonstrate the reversible nature of this system. The hydration behavior in powdery state under air atmosphere saturated by water was also investigated. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
92.
Synthesis of methacrylate polymer bearing cyanate groups and its chemoselective reaction with amines
Kousuke Tsuchiya Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2014,52(5):699-706
A novel reactive polymer containing cyanate groups in the side chain was prepared by free radical polymerization of a cyanate‐containing monomer, 2‐(4‐cyanatophenyl)ethyl methacrylate ( 1 ). The monomer 1 and its polymer, poly[2‐(4‐cyanatophenyl)ethyl methacrylate] (PCPMA), were stable under the air for a long period. The copolymerization of 1 and methyl methacrylate provided the corresponding copolymers with various cyanate contents. The availability of the cyanate‐containing polymers as a reactive polymer was investigated. Model reaction using 4‐cyanatotoluene revealed that a cyanate group reacted with aliphatic amines, whereas no reaction occurred in the presence of water, alcohols, and aromatic amines under mild conditions. Post‐functionalization of PCPMA was demonstrated using aliphatic amines or diamines. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 699–706 相似文献
93.
Bungo Ochiai Haruka Kojima Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2014,52(8):1113-1118
Polyhydroxyurethane bearing silicone backbone was prepared by polyaddition of silicone diamines with a bifunctional five‐membered cyclic carbonate prepared from the corresponding diepoxide and CO2. Polymerization in propylene glycol methyl ether acetate proceeded smoothly, and polymers could be obtained in high yields under appropriate conditions. The introduced silicone moieties improved the hydrophobicity and lowered the glass transition temperature keeping thermal stability. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1113–1118 相似文献
94.
Mina Sakuragi Naoto Aoyagi Yoshio Furusho Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2014,52(14):2025-2031
In this study, we investigated the CO2‐capture/release behavior of the polystyrene‐bearing cyclic amidine pendant groups, which was synthesized via free radical polymerization of HCl salt of the corresponding styrene monomer followed by neutralization. For comparison, we also prepared the polystyrene bearing N‐formyl‐1,3‐propanediamine pendant groups through the hydrolysis of the cyclic amidine group by treatment with an alkaline solution. First, we examined the CO2‐capture/release behaviors of the amidine and amine monomers in aqueous solution in terms of conductivity. The conductivity of a wet DMSO solution of the amidine monomer increased upon CO2 bubbling at 25 °C and reached a stationary value of about 11 mS/m, which indicated the formation of the bicarbonate salt. Conversely, the conductivity decreased to its original value upon N2 bubbling at 50 °C, reflecting the complete release of the trapped CO2 molecules. Both solutions showed the changes in the conductivity with quick responses, and no appreciable difference was observed between them. We then investigated the CO2‐capture/release behaviors of the amidine and amine polymers, by taking advantage of the binary system with polyethylene glycol, and found that the binary system with the amidine polymer captured and released CO2 more efficiently than that with the amine polymer. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2025–2031 相似文献
95.
96.
Synthesis of thermally stable aromatic poly(spiroorthocarbonate)s having a Cardo or bent structure
下载免费PDF全文
![点击此处可从《Journal of polymer science. Part A, Polymer chemistry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Masaki Moritsugu Ryota Seto Kozo Matsumoto Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2016,54(10):1409-1416
Novel poly(spiroorthocarbonate)s [poly(SOC)]s having a Cardo or bent structure were synthesized by polycondensation of several bis‐catechols having fluorene (BCFL), spirobisindane (BCSPI), or spirobischromane (BCSPC) in the structure with 2,2,6,6‐tetrachlorobenzo[1,2‐d:4,5‐d’]bis[1,3]dioxole (4ClBD). Synthesis of poly(SOC)s was confirmed by NMR and IR spectrometry. The poly(SOC)s obtained from BCFL or BCSPC were soluble in common organic solvents. The glass transition temperature of the poly(SOC)s was not detected by differential scanning calorimetry (DSC) in the range of 50–300 °C. The 10 wt % decomposition temperature of the poly(SOC)s was found to be above 400 °C. These results indicated the high thermal stability of the poly(SOC)s. Soluble poly(SOC)s could be possessed to form a film on a glass plate by the spin coat method. The obtained polymer films were 0.2 μm in thickness with 95% light transmission in the optical wavelength range. These results suggested that the Cardo or bent structure may block the packing of the main‐chain of the structure, which improves the solubility of the polymers, increases transparency, and enhances the thermal stability of SOCs. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1409‐1416 相似文献
97.
Ryota Seto Kozo Matsumoto Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2014,52(13):1832-1842
Reactivity of isothiocynate moieties in the side chain of polymethacrylate with amine, alcohol, or thiol was investigated, and the reactions were applied to preparation of networked polymers. Isothiocyanate of polymer side chain rapidly reacted with amines without a catalyst, to give the corresponding thioureas. However, it did not react with alcohols or thiols under the same conditions. Using 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) as a catalyst, addition of alcohols or thiols to the isothiocyanate proceeded smoothly. Addition of amines, alcohols, and thiols to isothiocyanates moiety contained in the side chain of polymethacrylate also proceeded readily with or without the catalyst, respectively, to effectively give the corresponding side chain modified polymers. Occurrence of these additions was confirmed by 1H NMR and IR measurements. Glass transition temperatures and thermal decomposition temperatures of the obtained polymers were investigated by differential scanning calorimetry and thermogravimetric analysis. Networked polymers were easily prepared by addition of 1,6‐hexamethylenediamine or hexamethylene glycol to the polymethacrylate having isothiocyanato groups. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1832–1842 相似文献
98.
Abstract The activation field for the switching time (τ1/2) in the truly ferroelectric liquid crystal 8SI* (CE8; ΔS-(+)-4-(2′-methylbutyl) phenyl-4′-n-octylbiphenyl-4 carboxylate) has been studied for various surface conditions of the transparent electrode (SnO2), in order to understand the memory effect, the polarization reversal mechanism and its surface effect. We prepared five different surfaces, namely one coated with polyvinyl alcohol (PVA) and the other four by scratching N-times(N = 0, 10, 20 and 30) with a paste made of Cr2O3 powder (about 0·1 μm). The number and the area of scratches on the electrode surface obviously increase with N. The polarization reversal processes are influenced by this treatment. τ1/2 decreases with increasing N, but no change is observed in the contrast of the light transmittance. Two different activation fields, E a1, for the applied field E > E 0 and E a2 for E < E 0 are observed, where E 0 is a certain field depending on the sample. Here E a1 is much larger than E a2; typically E a1, = 260 kV cm?1 and E a2 = 144 kV cm?1 for N = 0. This means that nucleation for the higher field needs a large activation energy which therefore has strong barriers. In contrast with this, nucleation for the low field occurs easily. Changing a surface condition, E a2 clearly decreases with increasing N although E a1 is almost independent of the surface scratching. This may suggest that E a1 corresponds to the activation field for the bulk pinning and nucleation, and E a2 for the surface pinning. The PVA treatment gives an intermediate influence between N = 0 and 10. 相似文献
99.
Asei William Kawaguchi Atsushi Sudo Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2014,52(3):410-416
1,3‐benzoxazine 1 , bearing 4‐pyridyl moiety on the nitrogen atom, was synthesized from p‐cresol, 4‐aminopyridine, and paraformaldehyde. The efficient synthesis was achieved by adding acetic acid to suppress the strong basicity caused by the presence of 4‐aminopyridine derivatives. Upon heating 1 at 180 °C, it underwent the thermally induced ring‐opening polymerization. The resulting polymer was composed of two types of repeating unit, i.e., (1) Mannich‐type one (‐phenol‐CH2‐NR‐CH2‐) that can be expected from the general ring‐opening polymerization of conventional benzoxazines and (2) a typical phenolic resin‐type one (‐phenol‐CH2‐phenol‐) induced by release of 4‐aminopyridine and paraformaldehyde (unit B). Another structural feature of the polymer was that it possessed a benzoxazine moiety at the chain end. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 410–416 相似文献
100.