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11.
12.
Yoshio Imai Mitsuru Ueda Kouetsu Otaira 《Journal of polymer science. Part A, Polymer chemistry》1977,15(6):1457-1463
A series of new polyarylamines was prepared by the vinylogous nuclephilic substitution polymerization of bis(4-chloro-3-nitrophenyl) sulfone with both aromatic and aliphatic diamines. The synthesis involves the solution polycondensation in a polar aprotic solvent at elevated temperatures, a tertiary amine being used as an acid acceptor. Of these solvents, dimethyl sulfoxide and N-methyl-2-pyrrolidone were the most effective for the preparation of high molecular weight polymers. The polyarylamines having inherent viscosities in the range of 0.1–0.5 were all amorphous and highly soluble in polar aprotic solvents. Thermogravimetric analysis under both air and nitrogen atmospheres indicated that rapid decomposition began above 300°C for the polyarylamines from aromatic diamines. 相似文献
13.
(+-)-3,3,7-Trimethyl-2,9-dioxatricyclo[4.2.1.04, 7]noname and (+-)-3,3,7-trimethyl-2,9-dioxatricyclo[3.3.1.04, 7] nonane were synthesized. The latter was shown to be (+-)-lineatin, an ambrosia beetle pheromone. 相似文献
14.
Tran QL Than MM Tezuka Y Banskota AH Kouda K Watanabe H Zhu S Komatsu K Thet MM Swe T Maruyama Y Kadota S 《Chemical & pharmaceutical bulletin》2003,51(6):679-682
Ginseng, the underground parts of plants of Panax species, has been used in oriental traditional medicine for centuries. Unfortunately, because of extensive exploitation over thousands of years, the natural source of these species has been almost exhausted. Recently, we have found a wild ginseng growing in Myanmar. Here, by a combination of chemical composition study and gene sequence analysis, we unambiguously demonstrate that the wild ginseng is actually P. zingiberensis, commonly known as ginger ginseng. This ginseng was an indigenous to the southwestern China. However, now it is seriously threatened to brink of extinction and is put on the highest level of protection in China. Therefore, an appropriate protection measure is highly recommended to preserve this valuable resource, since this Myanmar ginseng might turn out to be the last P. zingiberensis, which could ever be seen in the planet. 相似文献
15.
Poly(gamma-glutamic acid) (gamma-PGA) is a biosynthetic polymer, and the carboxyl groups are able to undergo a chemical modification. In this study, poly(alpha-propyl gamma-glutamate) (gamma-PGA propylate) was synthesized by the esterification of these carboxyl groups to yield a thermosensitive and biodegradable polymer. In aqueous solution, the gamma-PGA propylate can impart thermosensitivity by controlling the hydrophobic-hydrophilic balance of the gamma-PGA polymeric chains. 相似文献
16.
(±) - 33,7 - Trimethyl - 2,9 - dioxatricyclo[3.3.1.04,7]nonane 1 and (±) - 3,3,7 - trimethyl - 2,9-dioxatricyclo [4.2.1.04,7]nonane 2 were synthesized. The former was shown to be (±)-lineatin, an ambrosia beetle pheromone. A selective synthesis of (±)-lineatin was devised, which was modified to yield the both enantiomers of lineatin via optical resolution of an intermediate. 相似文献
17.
The effects of supporting electrolytes and of pressure on the electrode reactions of the aqueous CoW(12)O(40)(5-/6-) couple at 25 degrees C are reported, together with limited data on PW(12)O(40)(3-)/4-) and PW(12)O(40)(4-/5-). The half-wave potentials E(1/2) for the CoW(12) couple become moderately more positive with increasing electrolyte concentration and cationic charge, and also in the sequences Li(+) approximately Na(+) < NH(4)(+) < or = H(+) < K(+) < Rb(+) < Cs(+) and Na(+) < Mg(2+) < Ca(2+) < Eu(3+). The mean diffusion coefficients for CoW(12) with the 1:1 electrolytes are independent of electrolyte concentration and rise only slightly from Li(+) to Cs(+), averaging (2.4 +/- 0.3) x 10(-6) cm(2) s(-1). Neither the volumes of activation for diffusion Delta V(diff)(++) (average -0.9 +/- 1.1 cm(3) mol(-1)) nor the electrochemical cell reaction volumes Delta V(Ag/AgCl) (average -22 +/- 2 cm(3) mol(-1)) for the CoW(12) couple show significant dependence on electrolyte identity or concentration. For the PW(12)(3-/4-) and PW(12)(4-/5-) couples, Delta V(Ag/AgCl) = -14 and -26 cm(3) mol(-1), respectively, suggesting a dependence on Delta(z(2)) (z = ionic charge number) as predicted by the Born-Drude-Nernst theory of electrostriction of solvent, but comparison with Delta V(Ag/AgCl) for CoW(12) and other anion-anion couples shows that the Born-Drude-Nernst approach fails in this context. For aqueous electrode reactions of CoW(12), as for other anionic couples such as cyanometalates, the standard rate constants k(el) show specific cation catalysis (Na(+) < K(+) < Rb(+) < Cs(+)), and Delta V(el++) is invariably positive, in the presence of supporting electrolytes. For the heavier group 1 cations, Delta V(el++) is particularly large (10-15 cm(3) mol(-1)), consistent with a partial dehydration of the cation to facilitate catalysis of the electron-transfer process. The positive values of Delta V(el++) for the CoW(12) couple cannot be attributed to rate control by solvent dynamics, which would lead to Delta V(el++) < or = Delta V(diff++), i.e., to negative or zero Delta V(el++) values. These results stand in sharp contrast to those for aqueous cationic couples, for which k(el) shows relatively little influence of the nature of the counterion and Delta V(el++) is always negative. 相似文献
18.
Mitsuru Sano 《先进技术聚合物》1995,6(3):178-184
The redox behavior in acetone solution of (1,5-dithiacyclooctane 1-oxide)bis(pentaammineruthenium(II)) has been characterized, where the concept of “molecular hysteresis” is presented. Detailed thermodynamics for the complex are studied, in which intramolecular electron transfer rates for Ru3+OS/Ru2+→Ru2+SO/Ru3+ were determined as 0.12 sec?1 and 0.055 sec?1. The molecular hysteresis consists of two important factors: isomerizations for the sulfoxideruthenium complexes and the slow intramolecular electron transfer in the complex; both are examined. Isomerization rates for Ru3+S→O and Ru2+O→S determined range from 0.4 to 5000 sec?1 and from 0.7 to 16 sec?1, respectively, for [Ru(NH3)5(sulfoxide)]2+/3+. A mechanism for the slow electron transfer in the complex is also presented. Features of molecular hysteresis are discussed. 相似文献
19.
Toshio Yamanaka Mitsuru Ohkubo Fumie Takahashi Masayuki Kato 《Tetrahedron letters》2004,45(13):2843-2845
An efficient synthesis of the orally-active GpIIb/IIIa antagonist FR184764 was achieved. The key intermediate, an optically active ethynyl β-amino ester, was synthesized efficiently by utilizing a lipase catalyzed kinetic resolution step. 相似文献
20.
Mitsuru Ueda Toshitaka Koyama Motokazu Mano Masahiko Yazawa 《Journal of polymer science. Part A, Polymer chemistry》1989,27(3):751-762
Ethyl α-hydroxymethylacrylate (EHMA) was synthesized and homopolymerized in bulk and in solution. The poly(EHMA) is readily soluble in alcohol, acetone, tetrahydrofuran, and methylene chloride at room temperature. Intramolecular lactone formation occurred when poly(EHMA) was heated to 180–230°C. The kinetics of EHMA homopolymerization was investigated in ethyl acetate, using α,α′-azobisisobutylonitrile as an initiator. The rate of polymerization Rp was expressed by Rp = k[AIBN]0.50[EHMA]1.4 and the overall activation energy was calculated as 71.9 kJ/mol. Kinetic constants for EHMA polymerization were obtained as follows: kp/k = 0.17L0.9mol?0.9s?0.5; 2fkd = 1.5 × 10?5 s?1. The relative reactivity ratios of EHMA(M2) copolymerization with styrene (r1 = 0.472, r2 = 0.564) in ethyl acetate were obtained. Applying the Q-e scheme led to Q = 0.84 and e = 0.35 for EHMA. 相似文献