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991.
J. H. Adams J. E. Goodrich 《Journal of polymer science. Part A, Polymer chemistry》1970,8(5):1269-1277
The nonvolatile products of polypropylene that has been process degraded in the melt by a Brabender torque rheometer have been quantitatively identified by infrared analysis and chemical reactions carried out on molded sheets. The molecular weight changes with degradation have been determined by gel-permeation chromatography (GPC). It was determined that there is only one functional group per chain scission instead of the two groups previously found for thermal oxidation in the solid state. The molecular weight distribution is similar, but the functional groups and the general scheme of oxidation differ slightly from those previously found for polyolefin oxidation carried out below the melting point. The functional group distribution differs from that determined in a process-degraded polyethylene sample. 相似文献
992.
The reaction of Fe2(CO)6(μ-S2),1 withbis(dibenzylideneacetone)-palladium, Pd(dba)2, in the presence of 2,2′-bipyridine yielded the new compound Fe2(CO)6(μ 3-S)2Pd(bipy),2 in good yield (66%). Compound2 was characterized by IR,1H NMR and single-crystal X-ray diffraction analyses. Compound2 contains a Pd(bipy) group that has been inserted into the S-S bond of1. Crystal data for2: space group P21/n,a=10.019(2) Å,b=25.414(5) Å,c=7.714(2) Å,β=90.26(2)°,Z=4, 1436 reflections,R=0.023. 相似文献
993.
From the reaction of [Ru5(C)(CO)14]2– with Pt(COD)Cl2, COD=1, 5 cyclooctadiene, the new platinum-ruthenium carbido cluster complex PtRu5 (C)(CO)14(COD),1, was obtained in 41% yield. When1 was allowed to react with carbon monoxide (25°C/1 atm), the new complex PtRu5(C)(CO)16,2, was obtained almost quantitatively (97% yield). Compound2 was characterized by IR and single-crystal X-ray diffraction analysis. The six metal atoms are arranged in the form of an octahedron with the carbide ligand located in the center. Compound1 is believed to have a similar structure to2 except for a COD ligand coordinated to the platinum atom. When activated by treatment with Me3NO, compound2 reacts with Pt(COD)2 at 25°C to yield two higher nuclearity cluster complexes, Pt2Ru5C(CO)13(COD)2.3, and Pt3Ru5C(CO)14(COD)2,4. The structure of3 is similar to that of1, but contains a Pt(COD) grouping capping one Ru3 triangle of the PtRu5 octahedron. The structure of4 consists of a PtRu5 octahedron with two Pt(COD) capping groups, one on an Ru3 triangle and the other on a PtRu2 triangle of the octahedron. Crystal data: for2, space group=P21/n,a=9.341 (2) Å,b=14.957 (3) Å,c=36.80 (1) Å, =90.38 (2) °,Z=8, 4034 reflections,R=0.030, for3, space group=P21/c,a=14.998 (3) Å,b=10.288 (3) Å,c=26.581 (7) Å, =102.75 (2) °,Z=4, 2917 reflections,R=0.028. for4, space group=P21/n,a=13.412 (4) Å,b=16.252 (4) Å,c=20.107 (4) Å, =106.13 (2) °,Z=4, 2745 reflections,R=0.032. 相似文献
994.
Chris J. Adams Michael I. Bruce Brian W. Skelton Allan H. White 《Journal of Cluster Science》1992,3(2):219-227
The reaction between Ru5(5-C2PPh2)(-PPh2)(CO)13 and Au(C2Ph)(PPh3) afforded AuRu5(5-C2PPh2)(-C2Ph)(-PPh2)(CO)13 (PPh3), in which the Ru5 cluster has a scorpion geometry; the Au(PPh3) group bridges one of the Ru-Ru bonds of the Ru3 triangle, while the C2Ph group bridges one of the tail Ru-Ru vectors.For Part 84, see Ref. 1. 相似文献
995.
D. A. Lightner J.-S. Ma T. C. Adams R. W. Franklin G. L. Landen 《Journal of heterocyclic chemistry》1984,21(1):139-144
Xanthobilirubic acid, 5-[1,5-didehydro-3-ethyl-4-methyl-5-oxo-2H-pyrrol-2-ylidene)methyl]-2,4-dimethyl-1H-pyrrol-3-propanoic acid, its methyl ester, amide, N-methylamide and dimethylamide, and kryptopyrromethenone have been synthesized and characterized spectroscopically. In d6-DMSO solution all pyrromethenones were monomeric, with lactam and pyrrole N-Hs H-bonded to solvent. In deuteriochloroform, the pyrromethenones preferred a dimeric form, with intramolecular H-bonding between the lactam C = 0 of one unit and the lactam and pyrrole N-Hs of the second. 相似文献
996.
Brown CN Cooper WE Finley DA Jonckheere AM Jostlein H Kaplan DM Lederman LM Smith SR Luk KB Gray R Plaag RE Rutherfoord JP Straub PB Young KK Hemmi Y Imai K Miyake K Sakai Y Sasao N Tamura N Yoshida T Maki A Crittenden JA Hsiung YB Adams MR Glass HD Jaffe DE McCarthy RL Hubbard JR Mangeot P 《Physical review letters》1986,57(17):2101-2104
997.
998.
999.
Holman MW Liu R Zang L Yan P DiBenedetto SA Bowers RD Adams DM 《Journal of the American Chemical Society》2004,126(49):16126-16133
We report here on the systematic investigation of photoinduced intramolecular electron transfer (IET) in a series of donor-bridge-acceptor molecules as a means of understanding electron transport through the bridge. Perylenebisimide chromophores connected by various oligophenylene bridges are studied because their electron-transfer behavior can readily be monitored by following changes in the fluorescence intensity. We find dramatic switching of the IET behavior as the solvent polarity (dielectric constant) is increased. By combining steady-state and time-resolved fluorescence spectroscopy in a variety of solvents at multiple temperatures with standard theories of electron transfer, we determine parameters governing the IET behavior of these dimers, such as the electronic coupling through the bridges. We also deploy available ab initio quantum chemical methods to calculate the through-space component of the electronic coupling matrix element. Single-molecule investigations of the electron-transfer behavior also show that IET can be switched reversibly by a similar mechanism in an isolated individual molecule. 相似文献
1000.