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111.
The kinetic features of radical polymerization of styrene in the presence of primary and secondary aliphatic amines combined
with benzoyl peroxide and the molecular-mass characteristics of the resulting polymers were studied. In the presence of peroxide
initiators, aliphatic amines, as potential sources of stable aminoxyl radicals, provide the synthesis of polystyrene with
a controlled molecular mass without gel effect at a relatively high rate.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 159–164, January, 2007. 相似文献
112.
Bei-sheng Kang Mao-chun Hong Ting-bin Wen Han-qin Liu Jia-xi Lu 《Journal of Cluster Science》1995,6(3):379-401
Simple fragments of transition metal 1,2-bidentate thiolates, the so-called building blocks of the general compositions ML3, ML2, ML, M(O)L2, ML2L, MLL, etc. have been proposed to constitute the di-, tri- and tetranuclear complexes concerned in this review. Structureal regularities and characteristics have been discussed and summarized according to the thiolato ligands edt and pdt, bdt and tdt, mp, and mpo, and mpp, respectively.Abbreviations H2mpo
o-mercaptophenol
- Hmpo
2-mercaptopyridine-N-oxide
- R2dtc
N,N-dialkyldithiocarbamate
- Haet
2-aminoethanethiol
- H2bdt
o-benzenedithiol
- H2pdt
1,2-propanedithiol
- H2tdt
toluene-3,4-dithiol
- Hmpp-mppH
bis-(3-hydroxy-2-pyridyl)disulfide
- Hmp-mpH
bis-(2-oxyphenyl)disulfide
- H2edt
1,2-ethanedithiol
- dppe
1,2-bis(diphenylphosphino)ethane
- H2tedt
3,4,5,6-tetrachlorobenzene-1,2-dithiol
- H2tpdt
3-thiapentane-1,5-dithiol
- H2mnt
maleonitriledithiol
- Him
imidazole
- Bz
benzyl
- py
pyridine 相似文献
113.
114.
Synthesis and characterization of block copolymers from 2‐vinylnaphthalene by anionic polymerization
Faquan Zeng Mu Yang Jianxin Zhang Sunil K. Varshney 《Journal of polymer science. Part A, Polymer chemistry》2002,40(24):4387-4397
The anionic polymerization of 2‐vinylnaphthalene (2VN) has been studied in tetrahydrofuran (THF) at ?78 °C and in toluene at 40 °C. 2VN polymerization in THF, toluene, or toluene/THF (99:1 v/v) initiated by sec‐butyllithium (sBuLi) indicates living characteristics, affording polymers with predefined molecular weights and narrow molecular weight distributions. Block copolymers of 2VN with methyl methacrylate (MMA) and tert‐butyl acrylate (tBA) have been synthesized successfully by sequential monomer addition in THF at ?78 °C initiated by an adduct of sBuLi–LiCl. The crossover propagation from poly(2‐vinylnaphthyllithium) (P2VN) macroanions to MMA and tBA appears to be living, the molecular weight and composition can be predicted, and the molecular weight distribution of the resulting block copolymer is narrow (weight‐average molecular/number‐average molecular weight < 1.3). Block copolymers with different chain lengths for the P2VN segment can easily be prepared by variations in the monomer ratios. The block copolymerization of 2VN with hexamethylcyclotrisiloxane also results in a block copolymer of P2VN and poly(dimethylsiloxane) (PDMS) contaminated with a significant amount of homo‐PDMS. Poly(2VN‐b‐nBA) (where nBA is n‐butyl acrylate) has also been prepared by the transesterification reaction of the poly(2VN‐b‐tBA) block copolymer. Size exclusion chromatography, Fourier transform infrared, and 1H NMR measurements indicate that the resulting polymers have the required architecture. The corresponding amphiphilic block copolymer of poly(2VN‐b‐AA) (where AA is acrylic acid) has been synthesized by acidic hydrolysis of the ester group of tert‐butyl from the poly(2VN‐b‐tBA) copolymer. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4387–4397, 2002 相似文献
115.
Teruaki Hayakawa Shin Horiuchi Hiroshi Shimizu Tadashi Kawazoe Motoichi Ohtsu 《Journal of polymer science. Part A, Polymer chemistry》2002,40(14):2406-2414
Polystyrene‐b‐poly(1,2‐isoprene‐ran‐3,4‐isoprene) block copolymers with azobenzene side groups were synthesized by the esterification of azobenzene acid chloride with polystyrene‐b‐hydroxylated poly(1,2‐isoprene‐ran‐3,4‐isopenre) block copolymers for creating new photochromic materials. The resulting block copolymers with azobenzene side groups were characterized for structural, thermal, and morphological properties. IR and NMR spectroscopies confirmed that the polymers obtained had the expected structures. Differential scanning calorimetric measurements by heating runs clearly showed the glass transitions of polystyrene and polyisoprene main chains and two distinct first‐order transitions at temperatures of azobenzene side groups around 48 and 83 °C. The microstructure of these block copolymer films was investigated using both transmission electron microscopy (TEM) and near‐field optical microscopy (NOM). TEM images revealed typical microphase‐separated morphologies such as sphere, cylinder, and lamellar structures. The domain spacing of microphase‐separated cylindrical morphology in the NOM image agreed with that of the TEM results. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2406–2414, 2002 相似文献
116.
Two hydrophobic vinyl saccharide monomers based on D ‐glucose and D ‐fructose were polymerized by employing the reversible addition‐fragmentation transfer (RAFT) miniemulsion polymerization technique to prepare well‐designed glycopolymers. Three dithiobenzoate‐RAFT agents [S?C(Ph)S? R], 1‐phenylethyl dithiobenzoate (PED), 2‐phenylprop‐2‐yl dithiobenzoate (PPD), and 2‐cyanoprop‐2‐yl dithiobenzoate (CPD), were used to control the growth of polymer chains. The best results were obtained in the presence of the PPD‐RAFT agent and the formed polymers have polydispersity index's (PDI) lower than 1.15. Under adequate miniemulsion polymerization conditions, a glycopolymer with PDI of 1.1 and molecular weight of 5 × 104 g/mol has been successfully synthesized in a short reaction time of 100 min. Furthermore, some block copolymers containing saccharide segment with butyl or methyl methacrylate were prepared. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
117.
The kinetics and mechanism of thermal polymerization of acrylonitrile initiated by Mn(III) pyrophosphate — poly(ethylene glycol) (PEG, molecular weight 6000) redox system in aqueous sulfuric acid medium was studied in the temperature range 30–60°C. The overall rates of polymerization and the disappearance of Mn3+ were determined. The polymerization was initiated by the organic free radical produced from the Mn3+-PEG reaction and the termination was by the metal ions. The rate of polymerization of acrylonitrile was found to be directly proportional to the square of the monomer concentration and first power of PEG concentration, and inversely proportional to the concentration of Mn3+. The rate of manganic ion disappearance was found to be directly proportional to manganic ion concentration and PEG concentration, and independent of the monomer concentration. Based on these observations, a plausible reaction scheme was suggested and suitable kinetic expressions were evaluated. 相似文献
118.
Lumbierres M Palomo JM Kragol G Roehrs S Müller O Waldmann H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(24):7405-7415
A new flexible and efficient methodology for the solid-phase synthesis of lipidated peptides has been developed. The approach is based on the use of previously synthesized building blocks and overcomes the limitations of previously reported methods, since long doubly lipidated peptides can be synthesized by using this route. Furthermore, it was thus possible to prepare a large number of N- and H-Ras peptides bearing a wide range of reporter and/or linking groups--efficient tools for the investigation of biological processes. In terms of efficiency and flexibility this solid-phase method is superior to the solution-phase synthesis. It gives pure peptides in multimilligram amounts within a much shorter time and with superior overall yield. 相似文献
119.
采用氢核磁共振(1H-NMR)、动态光散射(DLS)及透射电子显微镜(TEM)对聚乙二醇-嵌段-聚甲基丙烯酸N,N-二甲氨基乙酯(PEG-b-PDMAEMA)三种具有不同PEG/PDMAEMA嵌段比的PEG-b-PDMAEMA共聚物在水溶液中的自聚集行为进行了研究. 研究表明, 两嵌段比例是影响聚合物胶束化过程的关键因素: 只有当其中聚乙二醇含量较低(质量分数低于33%)时, 聚合物才具有其pH/温度敏感胶束化特性. 此外, 共聚物溶液随温度胶束化过程与共聚物嵌段比大小密切相关. PEG-b-PDMAEMA这种不同于传统双亲性嵌段共聚物(DHBCs)在选择性溶剂中独特的胶束化行为, 是由聚合物溶液体系中各种基团之间的氢键作用决定的. 相似文献
120.
Takaya Hisano 《Tetrahedron letters》2005,46(37):6293-6295
Highly regioselective transformation of acyclic α,α′-alkenediols and their corresponding diacetates to monoacetates using lipase was accomplished. The acetylation of the α,α′-alkenediol regioselectively gave (E)-monoacetate, whereas the (Z)-monoacetate were obtained by hydrolysis of the α,α′-diacetate. 相似文献