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131.
A mild and efficient method for the synthesis of 1H-chromeno[2,3-d]pyrimidine-5-carboxamide derivatives via a one-pot, three-component reaction of an isocyanide, barbituric acid, and a salicylaldehyde in the presence of acetic acid in ethanol/water mixture at 75 °C is reported. This high atom economy reaction led to the construction of one benzopyran ring, and one amide group in a single synthetic step. 相似文献
132.
Loutfy H. Madkour Amera M. Hassanein Mohamed M. Ghoneim Safwat A. Eid 《Monatshefte für Chemie / Chemical Monthly》2001,132(2):245-258
Summary. The inhibition of corrosion of iron in 2 M nitric acid and 2 M sulfuric acid solutions by substituted phenylhydantoin, thiohydantoin, and dithiohydantoin compounds was measured using thermometric,
weight loss, and polarization methods. The three methods gave consistent results. The polarization curves indicated that the
hydantoin compounds act as mixed-type inhibitors. The adsorption of the inhibitors were found to obey the Temkin adsorption isotherm. The higher inhibition efficiency of the additives in nitric with respect to sulfuric acid solution may
be attributed to the reduced formation of soluble quaternary nitrogen salts in nitric acid medium, favouring adsorption of
the parent additive on the metal surface. The obtained results indicate that the corrosion rate of iron in both acids increases
with increasing temperature, both in absence and presence of the tested inhibitors. Kinetic-thermodynamic model functions
and Temkin isotherm data are compared and discussed. The synergistic effect of halide anions on the inhibition efficiency of the hydantoin
compounds was also investigated.
Received June 5, 2000. Accepted (revised) September 13, 2000 相似文献
133.
Matthias Westerhausen Sabine Weinrich Manfred Oßberger Norbert W. Mitzel 《无机化学与普通化学杂志》2003,629(4):575-577
The reaction of calcium‐bis[bis(trimethylsilyl)amide] with two equivalents triethylgallium yields nearly quantitatively the addition product. In the solid state the calcium atoms are coordinated by two nitrogen atoms and two ethyl groups, whereas in solution all ethyl substituents are magnetically equivalent even at low temperatures. The Ca‐C‐Ga two‐electron three‐center bonds show mean Ca‐N and Ca‐C distances of 243 and 268 pm, respectively. 相似文献
134.
135.
钒(Ⅴ)-7-碘-8-羟基喹啉-5-磺酸显色体系测定钢样中的钒 总被引:1,自引:1,他引:0
研究了7-碘-8-羟基喹啉-5-磺酸(H2QSI)在乙醇存在下分光光度法测定钡(Ⅴ)的最佳条件。在乙醇存在下pH4的硫酸介质中,(H2QSI)与V(Ⅴ)形成了红棕色配合物,最大吸收位于506nm处,表观摩尔吸光系数εmax=2.9×103L·mol-1·cm-1,有色配合物组成为V(Ⅴ):(H2QSI)=1:3。钒(Ⅴ)在0-14μg/25mL符合比耳定律、本法用于钢样中的测定,结果满意。H2QSI是光度分析中的一种显色剂,近年来,8-羟基喹啉类试剂用于钒(Ⅴ)的测定已有报道[1]:,H2QSI曾见用于稀土元素的光度测定[2],但用于钒(Ⅴ)的测定尚未见报道。本文研究了V(Ⅴ)与H2QSI的显色反应条件及组成,在pH4的乙醇介质中,V(Ⅴ)与H2QSI生成红棕色配合物ε506nm=2.9×103L·mol-1·cm-1。本方法用于低碳合金钢中钒的测定,结果满意。 相似文献
136.
A new method for introduction w-side chain of prostanoid was described in this note. Starting from acid chloride (3), via Barton radical reaction, a trans α,β-unsaturated ketone sython was introduced. 相似文献
137.
本实验建立了以抗坏血酸为基体改进剂测定蚝油中铅的方法。研究了多种基体改进剂消除蚝油基体对测铅的干扰,方法的相对标准偏差为4.9%,回收率为94%-96%,检出限为1.5ng/mL。本方法可用于蚝油、贻贝油等调味品中铅含量的测定。 相似文献
138.
139.
140.
Peter C. Junk Cameron J. Kepert Lioubov I. Semenova Brian W. Skelton Allan H. White 《无机化学与普通化学杂志》2006,632(7):1293-1302
A number of salts of 2,2′:6′,2″ ‐terpyridyl (‘tpy’) with univalent anions (halides : X = Cl, Br, I; oxyanions of increasing basicity: ClO4, NO3, ‘tfa’ = trifluoroacetate, ‘tca’ = trichloroacetate), variously solvated, have been structurally characterized by single crystal X‐ray studies. In all cases the tpy moieties are found to be doubly protonated [tpyH2]2+, the hydrogen atoms being associated with the nitrogen atoms of the peripheral rings, these together with the central nitrogen atom being directed towards a common focus, in most cases ‘chelating’ one of the counter‐ion components in diverse ways. Thus the chloride and bromide compounds are isomorphous [(tpyH2)X]+X−·H2O arrays; a second dihydrate phase is also described for the chloride, the two forms having the unchelated anion and water molecules engaged in hydrogen‐bonded networks essentially independent of [(tpyH2)X]+. The iodide is anhydrous, and of a different structural type, the anions, presumably too large for chelation, lying out of plane to either side, and linking different cations into a one‐dimensional polymer; in the perchlorate, the unsolvated aggregate is now discrete [(tpyH2)X2], a pair of perchlorate ions disposed to either side of the tpy plane, lying each with one oxygen atom interacting with both of the two protonating hydrogen atoms. In the anhydrous X = NO3, tfa, tca arrays, the lattices are solvated by the parent acids; one oxygen atom of each anion is chelated by the [tpyH2]2+ as in the chlorides, the other anion, with the acid, forming an independent ‘acid salt’ counterion [XHX]− in each case, retaining the additional protonic hydrogen rather than further protonating the central ring, all being of the form [(tpyH2)X]X·HX = [(tpyH2)X][X(HX)]. 相似文献