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981.
The synthesis of dimetallic olefin complexes of the type L1M1C7H7M2L2 (M1 = Fe, Co, Rh; M2 = Rh, Ir, Pd; L1 = CO, C5H5; L2 = diene, allyl, P(OR)3) is described. The fluxional structures were investigated by 13C-, 57Fe- and 103Rh-NMR.-spectroscopy, and a cisoid dimetallic coordination, including a (metal, metal)-bond, can be deduced for the C7H7-ring. 57Fe- and 103Rh-chemical shifts give indications for the charge distribution in the 34e-complexes. The homodimetallic complex (Cp)Rh(tropone)Rh(Cp) ( 13 , Cp = cyclopentadienyl) and the corresponding 2-methoxytropone complex 14 were synthesized in addition to the above mentioned complexes. A fluxional bis(1-3-η-allyl)-coordination of the two Rh-atoms was derived from the temperature-dependent 13C-NMR.-spectra. A spin simulation of the (Cp)-multiplets of 12 and 13 yields information about (Rh, Rh)-spin-coupling which amounts to ≈5 Hz at 30°. 相似文献
982.
In our previous research, multifunctional carboxylic acids have been used as flame retardants to reduce the flammability of cotton fleece so that the garment made of cotton fleece can pass the US mandatory requirement specified by the government regulation “Standard for the Flammability of Clothing Textiles” (16 CFR 1610). In this research, we studied and compared the effectiveness of the polycarboxylic acids having different numbers of carboxylic groups as the durable flame retardants for cotton fleece. The cotton fabrics were treated with 1,2,3,4-butanetetracarboxylic acid (BTCA), citric acid (CA), succinic acid (SUA) and malic acid (MLA). We compared the reactivity of those polycarboxylic acids to esterify cotton cellulose and their effectiveness to reduce the flammability of the cotton fleece. The data indicated that the polycarboxylic acids with higher functionalities (BTCA and CA) form more esterlinkages on cotton and are more durable to home launderings than that treated with their bifunctional counter parts (SUA and MLA, respectively). In addition, the cotton fabrics treated with BTCA and CA have higher dimensional stability and higher strength loss. All those differences can be attributed to the fact that only those acids with three or more carboxylic groups, i.e., BTCA and CA, are able to crosslink cotton cellulose whereas the bifunctional acids (SUA and MLA) only form single esterlinkage with cotton. 相似文献
983.
Anina Wöhl Dr. Wolfgang Müller Dr. Stephan Peitz Normen Peulecke Dr. Bhaskar R. Aluri Dr. Bernd H. Müller Dr. Detlef Heller Dr. Uwe Rosenthal Prof. Dr. Mohammed H. Al‐Hazmi Dr. Fuad M. Mosa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(26):7833-7842
In this paper we report the results of an extensive experimental kinetic study carried out on the novel ethylene trimerization catalyst system, comprising the chromium source [CrCl3(thf)3] (thf=tetrahydrofuran), a Ph2P‐N(iPr)‐P(Ph)‐N(iPr)H (PNPNH) ligand (Ph=phenyl, iPr=isopropyl), and triethylaluminum (AlEt3) as activator. It could be shown that the initial activity shows a first‐order dependency on the ethylene concentration. Also, a first‐order dependency was found for the catalyst concentration. The initial activity follows a typical Arrhenius behavior with an experimentally determined activation energy of 52.6 kJ mol?1. At elevated temperatures (ca. 80 °C), a significant deactivation was observed, which can be tentatively traced back to a ligand rearrangement in the presence of AlEt3. After a fast initial phase, a pronounced ‘kink’ in the ethylene‐uptake curve is observed, followed by a slow, almost linear, further increase of the total ethylene consumption. The catalyst composition, in particular the ligand/chromium and the cocatalyst/chromium molar ratio, has a strong impact on the catalytic performance of the trimerization of ethylene. 相似文献
984.
Yanfang Shen Tianying Xiong Hao Du Huazi Jin Jianku Shang Ke Yang 《Journal of Sol-Gel Science and Technology》2009,50(1):98-102
P, N, and Mo ternary co-doped nano TiO2 photocatalysts ((P, N, Mo)-TiO2) were prepared by a single step sol–gel method, which show much enhanced photocatalytic activities over Mo-TiO2, (P, N)-TiO2, un-doped TiO2 and Degussa P25 under visible light irradiation. The degradation rate of 0.72Mo–P-TiO2 is as high as 65.3%, which is about 6.7 times of that of Degussa P25. Possible reasons for the improvement of photocatalytic
activities were analyzed. 相似文献
985.
Nemanja Trišović Nebojša Banjac Nataša Valentić Gordana Ušćumlić 《Journal of solution chemistry》2009,38(2):199-208
The absorption spectra of nine compounds structurally related to phenytoin (5,5-diphenylhydantoin) were recorded in twelve
solvents over the range of 200 to 400 nm. The effects of solvent dipolarity/polarizability and solvent/solute hydrogen bonding
interactions were analyzed by means of the linear solvation energy relationship (LSER) concept proposed by Kamlet and Taft.
The lipophilic activity of the investigated hydantoins was estimated by calculation of their log 10
P values. The calculated values of log 10
P were correlated with the ratio of the contributions of specific and non-specific solute/solvent interactions. The correlation
equations were combined with the corresponding ED50 values to generate new equations that demonstrate exact relationship between solute/solvent interactions and the structure-activity
parameters. 相似文献
986.
Fatty acid profile of <Emphasis Type="Italic">Trichosanthes kirilowii</Emphasis> Maxim. seed oil 总被引:1,自引:0,他引:1
Fatty acid profile data for refined cold-pressed Trichosanthes kirilowii Maxim. seed oil, in comparison to other commercially available oils — olive, rapeseed and camellia, are presented. Trichosanthes kirilowii Maxim. seed oil has high oleic and linoleic acid content and high polyunsaturated acid content. Squalene elutes as a distinct
peak in the GC chromatograph. For a positive identification, MS detection was used. In the samples analyzed, squalene occurred
in the range of 57.4–68.2 mg g−1. 相似文献
987.
Four transition metal(II) complexes with podophyllic acid hydrazide (HL) were prepared and characterized by elemental analysis,
complexometric titration, thermal analysis, conductivity, IR, and 1H NMR. The complexes have the general formula ML2 · nH2O, where M = Zn, Cu, Co, and Ni, n = 2 or 0. Anti-tumor activities of podophyllotoxin, HL, ZnL2 · 2H2O, and NiL2 were tested by both the MTT and the SRB method. The results show that the activities of the complexes against the tumor cells
tested are superior to HL and the anti-tumor activity of NiL2 is even similar to that of podophyllotoxin. 相似文献
988.
Netto-Ferreira JC Lhiaubet-Vallet V de Oliveira Bernardes B Ferreira AB Miranda MA 《Photochemistry and photobiology》2009,85(1):153-159
The photochemical reactivity of β-lapachone ( 1 ), nor -β-lapachone ( 2 ) and 1,2-naphthoquinone ( 3 ) towards amino acids and nucleobases or nucleosides has been examined employing the nanosecond laser flash photolysis technique. Excitation (λ = 355 nm) of degassed solutions of 1 – 3 , in acetonitrile, resulted in the formation of their corresponding triplet excited states. These transients were efficiently quenched by l -tryptophan, l -tryptophan methyl ester, l -tyrosine, l -tyrosine methyl ester and l -cysteine ( k q ≈ 109 L mol−1 s−1 ). For l -tryptophan, l -tyrosine and their methyl esters new transients were formed in the quenching process, which were assigned to the corresponding radical pair resulting from an initial electron transfer from the amino acids or their esters to the excited quinone, followed by a fast proton transfer. No measurable quenching rate constants could be observed in the presence of thymine and thymidine. On the other hand, efficient rate constants were obtained when 1 – 3 were quenched by 2'-deoxyguanosine ( k q ≈ 109 L mol−1 s−1 ). The quantum efficiency of singlet oxygen (1 O2 ) formation from 1 to 3 was determined employing time-resolved near-IR emission studies upon laser excitation and showed considerably high values in all cases (ΦΔ = 0.6), which are fully in accord with the ππ* character of these triplets in acetonitrile. 相似文献
989.
The reaction force is a global property of a chemical reaction that arises when applying the Hellmann–Feynmann theorem to
the potential energy surface that links reactants, products and transition states. In the present work, the reaction force
is defined rigorously from the cartesian components coming out from all forces exerted over each atom of a molecular system
during the chemical reaction; it is demonstrated that the reaction force is a scalar property.
An erratum to this article can be found at 相似文献
990.
Yan Taihong Zhen Weifang Ye Guoan Zhang Yu Xian Liang Di Ying Bian Xiaoyan 《Journal of Radioanalytical and Nuclear Chemistry》2009,279(1):293-299
Dihydroxyurea (DHU) was synthesized using tri-associated solid phosgene [bis(trichloromethyl) carbonate] dissolved in dioxane and hydroxylamine hydrochloride dissolved in potassium acetate solution.
The reduction of Pu(IV) by DHU was investigated using UV-Vis spectrophotometry. The reduction back-extraction behavior of
Pu(IV) in 30% tri-butyl phosphate/kerosene was firstly investigated under conditions of various temperature, various DHU and
HNO3 concentrations and various phase contact times. The results showed that Pu(IV) in the organic phase can be stripped rapidly
to the aqueous phase by DHU. Simulating the 1B contactor of the PUREX process using a 0.1 M DHU in 0.36M nitric acid solution
as the stripping agent, the separation factors of uranium/plutonium can reach 2.1·104. This indicates that DHU is a promising salt free agent for uranium/plutonium separation. 相似文献