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261.
262.
Dr. Masashi Nakamura Yo Nakajima Prof. Dr. Nagahiro Hoshi Dr. Hiroo Tajiri Dr. Osami Sakata 《Chemphyschem》2013,14(11):2426-2431
The oxidation processes of a Pt(111) electrode in alkaline electrolytes depend on non‐specifically adsorbed ions according to in situ X‐ray diffraction and infrared spectroscopic measurements. In an aqueous solution of LiOH, an OHad adlayer is formed in the first oxidation step of the Pt(111) electrode as a result of the strong interaction between Li+ and OHad, whereas Pt oxidation proceeds without OHad formation in CsOH solution. Structural analysis by X‐ray diffraction indicates that Li+ is strongly protective against surface roughening caused by subsurface oxidation. Although Cs+ is situated near the Pt surface, the weak protective effect of Cs+ results in irreversible surface roughening due to subsurface oxidation. 相似文献
263.
264.
Shohei Inoue 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(5):651-664
Carbon dioxide and epoxide copolymerize in the presence of some organometallic catalyst systems under moderate conditions to give aliphatic polycarbonates of high molecular weight. Some metalloporphyrins of aluminum and zinc were found to act as novel catalysts for the polymerization of epoxide and for the copolymerization of carbon dioxide and epoxide, though not alternating. The polymers are characterized by the narrow molecular weight distribution and the unusual stereoregularity. Starting from the copolymerization of carbon dioxide and trimethylsilyl glycidyl ether with diethylzinc-water catalyst system, a readily degradable polycarbonate having hydroxyl group was obtained. 相似文献
265.
Pinacol-type coupling reaction products presenting a high meso-diastereoselectivity (the ratio dl/meso was 4/96 up to 1/99) were obtained in fair to good yields (24–69%) using several aromatic aldehydes as starting materials and aluminium powder/copper sulfate as catalysts, in water, under reflux conditions. 相似文献
266.
[reaction: see text] Treatment of allyl beta-iodoacetals with ethylmagnesium bromide in THF provided tetrahydrofuran derivatives in good yields. On the other hand, the reaction in DME provided tetrahydrofuranylmethylmagnesium compounds in good yields. 相似文献
267.
Citrin is the hepatic mitochondrial aspartate–glutamate carrier that is encoded by the gene SLC25A13. Citrin deficiency often leads to hyperammonemia, for which the current treatment concept is different from that for primary
hyperammonemias. Metabolite level diagnosis, often referred to as chemical diagnosis, is not always successful in identifying
citrin deficiency immediately or in a timely fashion. We previously made the chemical diagnosis of citrin deficiency in ten
patients from nine families. In order to devise a more rapid and more accurate chemical diagnosis of this disorder than is
currently available, we reinvestigated the gas chromatography/mass spectrometry-based urine metabolome in these patients.
In patients aged 2 to 5 months, prominent biomarkers detected included one or more of the following metabolites: tyrosine,
p-hydroxyphenyllactate, p-hydroxyphenylpyruvate, and N-acetyltyrosine, galactose, galactitol and galactonate, glucose, glucitol, and cystathionine. These biomarkers are less prominent
in older patients, but are not increased in argininosuccinate synthetase deficiency or other hyperammonemias. α-Ketoglutaramate
(KGM), a recently recognized urinary biomarker of primary hyperammonemias associated with defects of the urea cycle, was increased
in most patients with citrin deficiency studied here in spite of normal urinary levels of glutamine (the immediate precursor
of KGM), 5-oxoproline, glutamate, aspartate, and asparagine. Other important urinary biomarkers that should be measured for
differential diagnosis of hyperammonemias, including orotate, uracil, and β-ureidopropionate, were not increased. The presence
of citrulline and citrulline-derived metabolites was noted in all cases. The present study shows that noninvasive urine metabolomics,
together with an analysis of selected metabolites or groups of metabolites, provides a more reliable and rapid chemical diagnosis
of citrin deficiency than was previously available and more readily differentiates this disorder from other hyperammonemic
syndromes. 相似文献
268.
Yamada K Yagishita S Tanaka H Tohyama K Adachi K Kaizaki S Kumagai H Inoue K Kitaura R Chang HC Kitagawa S Kawata S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(11):2647-2660
Novel metal-complex assemblies constructed from the flexible hinge-like ligand H(2)bhnq (H(2)bhnq=2,2'-bi(3-hydroxy-1,4-naphthoquinone)) have been synthesized. The X-ray crystal structures of these compounds reveal that four types of architectures are accessible by variation of the metal ions. In copper(II) compounds 1-3, the chelating bhnq(2-) ions bridge copper(II) centers to form one-dimensional zigzag chains. The chains of 1-3 are arranged by hydrogen-bonding interactions and stacking interactions to produce porous structures. Cobalt(II) and zinc(II) compounds 4 and 5 form one-dimensional helical chains. In 4 and 5, the crystal packing induces spontaneous resolution of the helical chains with chiral cavities formed perpendicular to the helices. Nickel(II) compounds 6 and 7 form cyclic tetramers. The fourth architecture, a dimer (compound 8), is obtained by the reaction of zinc(II) and bhnq(2-) in MeOH. In these compounds, changes of the dihedral angles and the metal-coordination mode of the bhnq(2-) ion induce the structural versatility. The assemblies of the zigzag chains of the copper(II) compounds exhibit reversible vapochromic behavior. UV/Vis, powder X-ray diffraction, EPR, and adsorption isotherm measurements indicate that this vapochromic behavior is based on the hinge-like flexibility of the bhnq(2-) ion. 相似文献
269.
Nishiyama Y Kaneda M Saito R Mori T Wada T Inoue Y 《Journal of the American Chemical Society》2004,126(21):6568-6569
In the enantiodifferentiating photoaddition of ROH (R = Me, Et, i-Pr) to 1,1-diphenylpropene sensitized by fructosyl 1,4-naphthalenedicarboxylate in supercritical carbon dioxide, the enantiomeric excess of photoadduct increased with increasing bulkiness of the alcohol at all pressures used, with an accompanying sudden jump at the critical density, for which the enhanced clustering of alcohol, particularly in the subcritical pressure region, was revealed to be responsible from the fluorescence spectral examinations. 相似文献
270.
Wataru Sugimoto Masashi Omoto Katsunori Yokoshima Yasushi Murakami Yoshio Takasu 《Journal of solid state chemistry》2004,177(12):4542-4545
An ion-exchangeable ruthenate with a layered structure, K0.2RuO2.1, was prepared by solid-state reactions. The interlayer cation was exchanged with H+, C2H5NH3+, and ((C4H9)4N+) through proton-exchange, ion-exchange, and guest-exchange reactions. The electrical and magnetic properties of the products were characterized by DC resistivity and susceptibility measurements. Layered K0.2RuO2.1 exhibited metallic conduction between 300 and 13 K. The products exhibited similar magnetic behavior despite the differences in the type of interlayer cation, suggesting that the ruthenate sheet in the protonated form and the intercalation compounds possesses metallic nature. 相似文献