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21.
采用阳离子表面活性剂十六烷基三甲基溴化铵为模板剂,以正硅酸乙酯为硅源,以硫酸铝为铝源,水热合成了以催化油浆窄馏分为添加剂的高比表面积Al-MCM-41介孔分子筛,并利用XRD,HREM,TG-DTA及N2吸附-脱附等测试手段对合成样品进行了表征.合成的Al-MCM-41分子筛的比表面积和孔体积分别达到1295m2/g和1.5cm3/g,其平均孔径为4.3nm.重点研究了Al-MCM-41分子筛结晶度、晶胞参数、比表面积、孔体积及平均孔径等结构性质随催化油浆窄馏分添加量及其组成的变化规律,并从合成机理上进行了解释. 相似文献
22.
三核钨钼簇合物对苯乙烯氧化反应的催化 总被引:2,自引:0,他引:2
关于烯烃的催化氧化,报道较多。Takao等研究了苯乙烯在Ir和Rh络合物存在下的氧化反应;Collman曾报道环己烯在Vaska络合物[IrX(CO)(PPh_3)_2]催化下氧化成环己酮和环已烯氧化物。本文采用Cotton合成的簇合物[W_3O_2(CH_3CO_2)_6(H_2O)_3]Br_2· 相似文献
23.
V. S. Lenenko P. Kränke M. Wahren V. B. Shur M. E. Vol'pin 《Russian Chemical Bulletin》1995,44(7):1293-1299
The interaction of labeled dinitrogen complexescis-(Me2PhP)4Mo(15N2)2 andtrans-(dppe)2W(15N2)2 with non-labeled nitronium and nitrosonium fluoroborates,14NO2BF4 and14NOBF4, in sulfolane at room temperature in the presence of H2SO4 results in rapid formation of labeled nitrous and nitric oxides (15N14NO,15NO), as well as15N14N. The yield of the products depends on the reagent ratio and reaches 10–20 mol. % per mole of a complex under optimum conditions. The mechanism of the reactions found is proposed. It involves the step of protonation of the dinitrogen ligand to form the corresponding hydrazido(2–) derivatives, which are then attacked by nitronium or nitrosonium cations. In accordance with the mechanism proposed, it was established that the hydrazido(2–) complexes, (Me2PhP)3Mo(15N2H2)Cl2 and (dppe)2W(15N2H2)Cl2, are capable of forming15N14NO,15NO, and15N14N under the action of14NO2BF4 and14NOBF4 in the absence of an acid.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 13–13, July, 1995. 相似文献
24.
Thomas Kauffmann 《Angewandte Chemie (International ed. in English)》1997,36(12):1258-1275
Hitherto there was no reaction known that permits transformations of R1R2-CO → 0.5 R1R2R3C–CR1R2R3 in one step. This type of additive–reductive carbonyl dimerization is now possible using alkoxy(alkyl)tungsten(v) complexes with aromatic, heteroaromatic or α,β-unsaturated aldehydes and ketones. When a corresponding phenyl complex was employed in a test experiment, it was revealed that an aliphatic ketone could be used as the substrate in this reaction. A second interesting type of reaction is the transformation of CH3 ligands into μ-CH2 ligands, which occurs during the treatment of MeLi or Me3Al with molybdenum or tungsten chlorides (oxidation states VI and V, for Mo additionally IV) at low temperatures with liberation of CH4. Here, the question arises as to whether the intermediate involved has a terminal CH2 ligand (Schrock carbene complex) or a μ-CH3 ligand (CH3 bound by a two-electron three-center bond to two metal atoms). Of all the μ-CH2 complexes obtained, those which were synthesized by the action of MeLi on molybdenum chlorides can be recommended as reagents for carbonylmethylenation of aldehydes and ketones. They display high selectivity, very low basicity, a surprising resistance to protons, they are readily available, can be easily modified and, as regards their selective behavior, they have been investigated more thoroughly than other readily accessible carbonylmethylenation reagents of comparable selectivity. The results of NMR spectroscopic investigations on the structure of the μ-CH2 complexes, and associated reaction mechanisms are discussed. A survey of carbonylmethylenation reagents, which have been reported in the literature, permits comparisons to be made with carbonylmethylenating molybdenum and tungsten complexes. 相似文献
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26.
Metathesis of hex-1-ene in ionic liquids catalyzed by WCl6 was studied. The metathesis is preceded by isomerization of hex-1-ene to hex-2-ene, from which the main reaction product, viz., oct-4-ene, is derived. The WCl6-1-butyl-3-methylimidazolium tetrafluoroborate (BMIM·BF4) system efficiently catalyzes metathesis of linear olefin, the ionic liquid serving as the reaction medium by forming a stable homogeneous catalytic system with WCl6. The yields of the metathesis products increase with increasing reaction temperature. The addition of tin-containing promoters leads to a substantial increase in the reaction rate. In the WCl6-BMIM·BF4-SnBu4 system, the selectivity of the formation of oct-4-ene is significantly enhanced.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2094–2097, October, 2004. 相似文献
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28.
《Arabian Journal of Chemistry》2020,13(9):7183-7198
The extraction of Zea mays hairs (Z. mays) was carried out by soxhlet and ultrasound techniques and through three solvents. Phytochemical tests and quantitative analysis of total phenols content (TPC) and flavonoids content (FC) for all extracts were also determined. The antioxidant activity, for different fractions, was determined by using three methods; DPPH, FRAP and TAC. All extracts were rich in polyphenols and the analysis of TPC and FC showed that the hydro-ethanolic extract obtained by ultrasound was characterized by a significant amount of TPC and FC. The n-butanolic fraction was rich in FC and also had a very high antioxidant capacity. On the other hand, the inhibiting effect of hydro-ethanolic extract, n-butanolic fraction and standard (flavone) on mild steel corrosion in 1 M HCl solution was investigated by electrochemical measurements. The polarization curves along with EIS diagrams indicated that flavone was the major molecule responsible for inhibition and acted as mixed-type inhibitor with predominant control of cathodic reaction. The antioxidant activity of BF was well correlated to corrosion inhibition efficiency. 相似文献
29.
An all solid-state electrochromic smart window employing prussian blue and electrodeposited WO3 film with poly (vinyl chloride) (PVC) gel electrolyte that has high conductivity (2 mS/cm) at room temperature has been fabricated
for the first time. The smart window has beell found to be excellent for electrochromism and memory characteristics. 相似文献
30.
本文给出了一个计算二元矩阵分叉连分式插值的系数算法以及与此算法等价的矩阵算法,这种算法是用矩阵广义逆意义下定义的矩阵行、列初等变换而给出的. 相似文献