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91.
Ona Illa Aimée El-Kazzi Heinz Gornitzka Antoine Baceiredo Vicenç Branchadell 《Tetrahedron》2009,65(12):2451-2454
α-(trans-Vinyl) phosphonamides with different substituents at the β-position were stereoselectively synthesized in high yields by treatment of β-substituted α-epoxy-α-trimethylsilyl phosphines with oxidizing agents. The corresponding phosphonamides were unstable in most cases and underwent reductive elimination affording desilylated vinyl derivatives. In turn, α-epoxy phosphines resulted from the [1+2] addition of [bis(diisopropylamino)phosphino](trimethylsilyl)carbene 2 to aliphatic, aromatic, and heteroaromatic aldehydes. In this way, a great variety of vinyl compounds have been efficiently prepared through one-pot procedure. 相似文献
92.
Joshua A. Luthy 《Journal of solid state chemistry》2009,182(3):580-15261
Na2Mn2S3 was oxidatively deintercalated using iodine in acetonitrile to yield Na1.3Mn2S3, with lattice constants nearly identical to that of the reactant. Lithium was then reductively intercalated into the oxidized product to yield Li0.7Na1.3Mn2S3. When heated, this metastable compound decomposed to form a new crystalline compound, LiNaMnS2, along with MnS and residual Na2Mn2S3. Single crystal X-ray diffraction structural analysis of LiNaMnS2 revealed that this compound crystallizes in P-3m1 with cell parameters a=4.0479(6) Å, c=6.7759(14) Å, V=96.15(3) Å3 (Z=1, wR2=0.0367) in the NaLiCdS2 structure-type. 相似文献
93.
Reaction of the tetranuclear complex [PtIMe3]4 with the ligand (S)- and (R)-Ph2P(C6H4)CHNC*H(Ph)Me in a 1:4 molar ratio yields the mononuclear neutral complexes in diastereoisomeric mixtures [PtIMe3{κ2-Ph2P(C6H4)CHNC*H(Ph)Me-P,N}]. Iodide abstraction from mixture with AgBF4 in the presence of pyridine (Py) induces a reductive elimination reaction with loss of ethane, leading to the cationic complex [PtMe(Py){κ2-Ph2P(C6H4)CHNC*H(Ph)Me-P,N}][BF4] [C* = (S)-, 3; (R)-, 4]. When this reaction was carried out in the presence of PPh3 a consecutive orthometallation reaction with loss of methane is produced, forming the cationic complex [Pt(PPh3){κ3-Ph2P(C6H4)CHNC*H(C6H4)Me-C,P,N}][BF4], [(S)-, 5; (R)-, 6]. All species were characterised in solution by 1H and 31P{1H} NMR spectroscopy, elemental analysis and mass spectrometry.The crystal structure of the diastereoisomer (OC-6-44-C)-[PtIMe3{κ2-(R)-Ph2P(C6H4)CHNC*H(Ph)Me-P,N}] has been determined by single-crystal X-ray diffraction. 相似文献
94.
近年来,基于多相纳米金(Au)催化的绿色合成与清洁反应研究引起了人们的广泛关注。与传统的铂族金属催化剂相比,纳米Au催化剂在控制反应选择性、高收率获得目标产物以及实现高效简约的一锅法串联反应合成等符合"原子经济"及"步骤经济"等绿色化学理念的新反应及新过程方面展现了其独特的优势,已成为当前绿色催化领域研究的热点和前沿。主要综述了我们研究小组在纳米Au催化绿色合成领域,尤其是利用纳米Au催化高效制取含氮精细有机化合物及生物质资源高值化利用方面所取得的研究进展,介绍了各类反应的特点、优势及在合成中的应用。 相似文献
95.
The extended Poincaré–Lighthill–Kuo (PLK) method is applied to characterize head-on collisions of solitary waves in a coupled Korteweg–de Vries (KdV) system that has multiple modes supporting solitons. As a simple physically realizable system, we investigate two coupled electrical nonlinear transmission lines (NLTLs), and the proposed method successfully leads to the collision-induced phase shifts and the wave equation that governs the dynamics of the pulses generated by colliding solitary waves. 相似文献
96.
Qun Feng Zhang Jia Chun Wu Chang Su Feng Feng Qiao Ling Ding Zhao Lian Yuan Hong Wang Lei Ma Chun Shan Lu Xiao Nian Li 《中国化学快报》2012,23(10):1111-1114
A novel egg-shell Pd-S catalyst with palladium metal as the core and a membrane of palladium sulfide as the surface has been prepared by sulphidizing Pd/C with H2S.This catalyst is effective for the reductive alkylation of p-amino diphenylamine(PADPA) and methylisobutyl ketone(MIBK) to afford N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenedianine(DBPPD) with conversion up to 99.42%and selectivity to 97.46%.Comparing with the other common palladium sulfide catalysts,the membrane of palladium sulfide on the surface and the core of palladium metal cause the Pd on the surface of the new catalyst in a lower sulfur coordination, which improves its activity.Our result indicates that this new egg-shell Pd-S/C is an efficient hydrogenation catalyst. 相似文献
97.
A concise total synthesis of (+)-deoxocassine (1) and (−)-deoxoprosophylline (2) has been achieved for the first time from d-xylose. The key steps involved in these synthesis are alkyl Grignard reaction, SN2 substitution of mesylate by azide, Wittig reaction, and reductive amination. 相似文献
98.
The reaction of free base or Ni(II) complex secochlorin bisaldehydes 4H2 and 4Ni regenerates the ultimate starting material of the bisaldehydes, meso-tetraphenylporphyrin 2H2 and 2Ni, respectively. Depending on the reaction conditions employed (hydrazine hydrate in pyridine at reflux or hydrazine hydrate activated with sulfur in the presence of aqueous NaOH at ambient temperature), either porphyrin 2H2 is formed together with known dihydroxymorpholinochlorin 9H2 or known 2-hydroxychlorin 8H2. Two different reaction pathways for the hydrazine reaction can be derived, either involving the formation of a meso-tetraphenyl-1,4,5-triazepinoporphyrin that loses spontaneously N2 or a Wolff-Kishner-type pathway that also involves an intramolecular aldol-type reaction. Neither reaction is synthetically useful but both highlight in an impressive fashion the high thermodynamic stability of porphyrins. They also bring the ‘breaking and mending of porphyrin’ strategy to its ultimate conclusion by regenerating the starting porphyrin. 相似文献
99.
Gilles Argouarch Guillaume Grelaud Thierry RoisnelMark G. Humphrey Frédéric Paul 《Tetrahedron letters》2012,53(37):5015-5018
The reductive etherification of aldehydes can be performed by the reaction with dialkylmethylsilanes in the presence of new iron(II) piano-stool catalysts of general formula Cp∗Fe(CO)2Ar (Cp∗ = η5-C5Me5; Ar = Ph, 4-C6H4OCH3, 4-C6H4CH3, Fc). This transformation is promoted by UV light and affords a simple route for the preparation of unsymmetrical alkyl ethers. 相似文献
100.
In this work, we characterize a previously synthesized multi-cationic aminopyrene-based labeling tag for oligosaccharide analysis by capillary electrophoresis with laser-induced fluorescence detection (CE/LIF). The fluorescent tag, 4,4',4''-(8-aminopyrene-1,3,6-trisulfonyl)tris(1-methylpiperazine) (APTMP), was characterized by reaction with standard maltooligosaccharides and the labeling parameters such as fluorescent tag concentration, labeling temperature, and time as well as influence of a reducing agent and its solvent were investigated in terms of labeling efficiency. The nanomolar limit of detection of CE/LIF analysis of APTMP labeled maltopentaose was determined. However, significant amount of the oligosaccharides was reduced to alditols, which negatively affects the yield and rate of the labeling reaction. Under optimized conditions, a highly reproducible labeling by multi-cationic APTMP was obtained; however, the most commonly used labeling by multi-anionic 8-aminopyrene-1,3,6-trisulfonic acid trisodium salt (APTS) is superior compared to APTMP labeling. Lower reactivity of APTMP compared to APTS can be explained by the loss of nucleophilicity induced by substitution of the sulfonate groups with more electron-withdrawing aminosulfonyl ones. On contrary, APTMP is still a promising tag for oligosaccharide labeling followed by CE-MS in a positive ion mode, which is considered to be more sensitive than MS detection of APTS in a negative ion mode. 相似文献