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961.
Platinum intercalated into a hydrotalcite-like solid, Mg0.74Al0.26(OH)2(NO3)0.26, was found to catalytically reduce interlayer nitrate (NO3-) to N2/N2O so as to give rise to a large surface area micro/mesoporous structure at lower temperature of ca. 300 degrees C, compared to 500 degrees C required for the decomposition of the pristine hydrotalcite phase. 相似文献
962.
W. Lyoo J. Yeum H. Ghim J. Park S. Lee J. Kim D. Shin J. Lee 《Colloid and polymer science》2003,281(5):416-422
To precisely identify the effect of the molecular weight of syndiotactic poly(vinyl alcohol) (s-PVA) on the water stability of a s-PVA/iodine complex film, we prepared four s-PVAs with similar syndiotactic diad (s-diad) contents of about 63% and with different number-average degrees of polymerization, Pn, of 900, 6,000, 10,000, and 17,000, respectively. The desorption behavior of iodine in the s-PVA/iodine complex film in water was investigated in relation to the solubility of s-PVA in water. The degree of solubility of a s-PVA film having different Pn in water at 80 °C was limited to about 0.3-10%, whereas the degrees of solubility of atactic PVA films with Pn of 6,000 and 10,000 were 100% at the same conditions. The degree of iodine desorption of the complex film decreased with increasing Pn of s-PVA. Especially, the degree of iodine desorption of a PVA drawn film having Pn of 17,000 was limited to 2%, regardless of soaking temperature from 40 to 80 °C. The desorption of iodine in water was strongly affected by the dissolution of PVA. In addition, the degree of iodine desorption of the drawn s-PVA/iodine film was larger than that of the undrawn one. 相似文献
963.
Fujio Mizukami Yoshimichi Kiyozumi Tsuneji Sano Shu-ich Niwa Makoto Toba Shigemitsu Shin 《Journal of Sol-Gel Science and Technology》1998,13(1-3):1027-1031
Amorphous alumina-silicas were prepared from a tetra-alkoxysilane and anhydrous aluminum trichloride or an aluminum alkoxide by a sol-gel process using 2-methyl-2,4-pentanediol, pinacol, 1,2-propanediol, 2,3-butanediol or ethylene glycol as the solvent or complexing agent, and the effect of diols and alkoxy groups on the physical and chemical properties of the alumina-silicas was examined. When the diol or the alkoxy group was bulky, the alumina-silicas had relatively larger micropores, a larger pore volume and higher surface areas. In the conversion of methanol catalyzed by the alumina-silicas, the bulkier diols and alkoxides gave catalysts that produced dimethyl ether in higher yield and hydrocarbons in lower yield. Thus, when ethylene glycol was used as the diol, the best catalyst for the production of hydrocarbons, especially the production of olefins such as ethylene, propylene and butene, was obtained. Furthermore, in comparison with alumina-silica prepared by a traditional kneading process, it was found that the sol-gel alumina-silica could efficiently convert methanol to dimethyl ether and hydrocarbons, but the material prepared by kneading had a very low conversion of methanol to other compounds. 相似文献
964.
Iwao Ojima Mitsuru Nihonyanagi Tetsuo Kogure Miyoko Kumagai Shuji Horiuchi Kimiyo Nakatsugawa Yoichiro Nagai 《Journal of organometallic chemistry》1975,94(3):449-461
The hydrosilylation of various carbonyl compounds such as simple aldehydes, simple ketones, α,β-unsaturated carbonyl compounds, α-diketones, acyl cyanides and ketones having an electron-withdrawing group on the α-carbon using tris(triphenylphosphine)chlororhodium as a catalyst is described. Solvolysis of these silyl ethers and silyl enol ethers afforded the corresponding reduced products. The hydrosilylation of α,β-unsaturated carbonyl compounds was found to proceed by 1,4-addition. An oxidative adduct of triethylsilane to the rhodium-(I) complex was obtained as a reaction intermediate. The structure of the adduct was discussed on the basis of its IR and far-IR spectra. 相似文献
965.
Brill D Ahner W Baltes P Barth R Bormann C Cieslak M Debowski M Grosse E Henning W Koczon P Kohlmeyer B Miskowiec D Müntz C Oeschler H Pöppl H Pühlhofer F Sartorius S Schicker R Senger P Shin Y Speer J Stein J Stiebing K Stock R Ströbele H Völkel K Wagner A Walus W 《Physical review letters》1993,71(3):336-339
966.
Supramolecular chirality was optically induced in amorphous and achiral azobenzene polymer films by irradiation of a laser beam with elliptical polarization. The chirality resulted from helical orientation of azobenzene chromophores by a combined process of circular and linear polarization. The helix-handedness could be controlled by incident light-handedness. 相似文献
967.
A method has been developed for the determination of traces of mercury in bismuth by neutron activation analysis. After sample irradiation at a flux of 7 · 1013 n cm-2 s-1 for 20 min, mercury was separated from bismuth by addition of ammonium sulfide and re-dissolution of bismuth (matrix) sulfide with nitric acid, and filtration of sulfur containing mercury on a membrane filter. The activity of the 68- or 68–77-keV region, counted with a Ge(Li) or NaI(Tl) detector, was used for quantitative measurements. The method was applied to bismuth samples containing 0.1–100 p.p.m. of mercury. 相似文献
968.
The palladium-catalyzed three-component coupling reaction (TCCR) of aryl isocyanides, allyl methyl carbonate, and trimethylsilyl azide was conducted in the presence of Pd(2)(dba)(3).CHCl(3) (2.5 mol %) and dppe (1,2-bis(diphenylphosphino)ethane) (10 mol %). Allyl aryl cyanamides with a wide variety of functional groups were obtained in excellent yields. This palladium-catalyzed TCCR was further utilized for the synthesis of N-cyanoindoles. The reaction of 2-alkynylisocyanobenzenes, allyl methyl carbonate, and trimethylsilyl azide in the presence of Pd(2)(dba)(3).CHCl(3) (2.5 mol %) and tri(2-furyl)phosphine (10 mol %) at higher temperatures afforded N-cyanoindoles in good to allowable yields. (eta(3)-Allyl)(eta(3)-cyanamido)palladium complex, an analogue of the bis-pi-allylpalladium complex, is a key intermediate in the TCCR, and a pi-allylpalladium mimic of the Curtius rearrangement is involved to generate the (eta(3)-allyl)(eta(3)-cyanamido)palladium intermediate. 相似文献
969.
Shigeo Horiuchi 《无机化学与普通化学杂志》1971,386(2):208-212
The continuous variations of reflexion intensities and lattice spacings are observed for the transformation from mackinawite. FeS (tetragonal), to greigite, Fe3S4 (cubic). by electron beam heating. At the beginning of the transformation, the (222) reflexion of greigite appears. At the end, the (400) and (220) reflexions of greigite are stronger than those so far reported, and the (311), (422) and (331) reflexions are weaker. The observations suggest, that the (101) plane of mackinawite changes to the (222) plane of greigite. The transformation proceeds by bulk diffusion of sulfur, which initially existed in an amorphous state on the surface of mackinawite. 相似文献
970.
Lee SH Kim HK Seo JM Kang HM Kim JH Son KH Lee H Kwon BM Shin J Seo Y 《The Journal of organic chemistry》2002,67(22):7670-7675
Arteminolides B-D (2-4), new farnesyl protein transferase inhibitors, were isolated together with a known arteminolide A (1) and new regioisomers (5-7) of the compounds from the aerial parts of Artemisia argyi. Structures of these compounds were elucidated by spectroscopic methods and chemical conversion. Arteminolides inhibited the farnesyl protein transferase with IC(50) values of 0.7-1 microM, while the regioisomers 5-7 were inactive. In addition, it was proved that the exocyclic double bond of sesquiterpene lactone did not affect the inhibitory activity of arteminolide. The effects of compound 2 on H-Ras processing and cellular growth in H-ras-transformed cells were also evaluated. 相似文献