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101.
Caterina Costa Carmela Cavalcante Francesca Zito Yukio Yokota Valeria Matranga 《Molecular diversity》2010,14(4):653-665
The extracellular matrix protein Pl-nectin, a 210-kDa homodimer originally purified from sea urchin eggs, plays a crucial role in cell adhesion and embryonic
morphogenesis. The compiled cDNA sequence, obtained by RT-PCR primer walking and 3′ RACE, identified a 984aa product containing
a 23aa signal peptide and including all six internal peptides identified by protein microsequencing. The protein is a new
member of the galactose-binding protein superfamily as it consists of six 151–156aa-long tandemly repeated domains (D1–D6),
homologous to the discoidin-like domains, also known as F5/8-type C domains. Based on homology modelling, we present a three-dimensional
structure (3D) for D5, identified as the prototype domain. The molecular modelling of the assembled Pl-nectin homodimer accounts for a Pl-nectin quaternary structure composed of two 105-kDa C-shaped monomers linked by a S–S bridge. The presence of an LDT motif
between the first and the second exposed loops of the D2 domain suggests the binding of Pl-nectin to an integrin receptor. Altogether, the in silico analysis described here is consistent with previous biochemical
reports and offers a basis for predictions to be experimentally tested. 相似文献
102.
103.
Masami Kuriyama Satoko Tanigawa Yuki Kubo Yosuke Demizu Osamu Onomura 《Tetrahedron: Asymmetry》2010,21(11-12):1370-1373
A facile synthetic method toward optically active 3,3-disubstituted oxindoles with excellent enantioselectivity was achieved using chiral copper-catalyzed desymmetrization of prochiral 1,3-diols. The monotosylated product was transformed into oxindole derivatives efficiently. 相似文献
104.
Abstract The polymerizations of alkyl esters of propiolic acid by Rh complex catalysts were investigated. [Rh(norbornadiene)Cl]2, which was the most active among the catalysts examined, gave rise to poly(alkyl propiolate) in a fairly high yield (~80%) in the presence of alcohol as the polymerization solvent. The polymers formed were a pale yellow powder soluble in common organic solvents except for poly(methyl propiolate). The structures of the polymers obtained were investigated by IR, 13C-NMR, CP MAS 13C-NMR, and laser Raman spectroscopies, together with the x-ray diffraction method. Based on these spectroscopic data, it was concluded that this Rh complex can be called a stereoregular polymerization catalyst of alkyl propiolate because the poly(alkyl propiolate) obtained has a cis-transoidal structure. 相似文献
105.
Hidefumi Hirai 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(11):1491-1500
Terephthalic acid was synthesized by the carboxylation of benzoic acid with carbon tetrachloride in aqueous sodium hydroxide solution in the presence of cyclodextrin (CyD) and copper powder as catalyst. By the use of β-CyD at the initial molar ratio to benzoic acid of 0.5, the carboxylation at 60 °C for 7 hours produced terephthalic acid in 75 mol% yield with 87% selectivity. The selective synthesis of 4,4'-biphenyldicarboxylic acid in 70 mol% yield was achieved by the carboxylation of 4-biphenylcarboxylic acid with carbon tetrachloride in the presence of β-Cyd under similar conditions. The carboxylation of 2-naphthalene carboxylic acid with carbon tetrachloride using β-Cyd under similar conditions produced 2,6-naphthalenedicarboxylic acid in 67 mol% yield with 84% selectivity. When α-CyD and γ-CyD were used in place of β-Cyd, both the yields and the selectivities of the dicarboxylic acids were markedly small. In the absence of CyD, carboxylation did not proceed. Inclusion complex formations between β-Cyd and aromatic monocarboxylic acids were indicated by the 1H chemical shifts of the β-Cyd. The reaction mechanism was discussed on the basis of inclusion complex formation. 相似文献
106.
Toyoji Kakuchi Toshifumi Satoh Junji Mata Satoshi Umeda Hisaho Hashimoto Kazuaki Yokota 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(3):325-336
Abstract The cyclopolymerizations of 1,2:5,6-dianhydro-3,4-di-O-pentyl-D-mannitol (1b) and 1,2:5,6-dianhydro-3,4-di-O-decyl-D-mannitol (1c) were carried out using BF3OEt2 and t-BuOK. All the resulting polymers consisted of cyclic constitutional units, i.e., the extent of cyclization was 100%. The polymer structures for the polymerization with t-BuOK were (1→6)-2,5-anhydro-3,4-di-O-pentyl-D-glucitol (2b) and (1→6)-2,5-anhydro-3,4-di-O-decyl-D-glucitol (2c), whereas those with BF3O-decyl2 comprised 2,5-anhydro-D-glucitols as major units along with other cyclic ones. These polymers were soluble in n-hexane, CHCl3, and THF, but insoluble in water, which differs from the amphiphilic solubility of (1→6)-2,5-anhydro-3,4-di-O-methyl-D-glucitol (2a). The cation-binding properties of 2b and 2c were examined using alkali-metal picrates in order to compare them with those of 2a. The extraction yields for each cation decreased in the order of 2c < 2b < 2a. Every polymer exhibited a similar cation-binding selectivity in the order Cs+ > Rb+ > K+ ? Na+ > Li+. The ratio of K+ and Na+, K+/Na+, was 4.6 for 2a, 5.1 for 2b, and 7.1 for 2c in the increasing order 2a < 2b > 2c. 相似文献
107.
Hidefumi Hirai 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9-11):1293-1303
Macromolecule-copper(I) chloride complexes have been prepared for the separation of carbon monoxide and ethylene from gas mixtures with hydrogen, nitrogen, carbon dioxide, methane, and water. A toluene solution of a polystyrene-aluminum copper(I) chloride complex can separate carbon monoxide selectively and retains this function even on contact with gas containing water. Strong charge-transfer absorption bands have been found in the 380-500 nm region for the toluene solution of polystyrene-aluminum copper(I) chloride complex. A solution of 1, 3-diphenylpropane-aluminum copper(I) chloride complex also exhibits similar absorption bands. A continuous variation plot using the chemical shift change in 13C-NMR shows a 1:1 interaction between 1,3-diphenylpropane and aluminum copper(I) chloride. These results suggest a two-way interaction between the adjacent phenyl groups of polystyrene and aluminum copper(I) chloride. A resin bead of crosslinked polystyrene-aluminum copper(I) chloride complex has been prepared as a solid adsorbent. The water resistance of the solid macromolecular complex depends on the nature of the solvent used in the preparation of the solid adsorbent. Carbon disulfide is a suitable solvent. A selective adsorbent of ethylene has been prepared from a macroreticular polystyrene resin with primary and secondary amino groups and copper(I) chloride. The selectivity of ethylene against ethane and that of carbon monoxide against carbon dioxide increase with an increasing amount of supported copper(I) chloride. 相似文献
108.
109.
Masami Sakamoto Kazuya Yoshiwara Fumitoshi Yagishita Wataru Yoshida Takashi Mino Tsutomu Fujita 《Research on Chemical Intermediates》2013,39(1):385-395
The irradiation of methyl 2- and 3-chromonecarboxylate in the presence of various alkenes afforded cyclobutane type adducts, whose structures were established by X-ray structural analysis. Methyl 2-chromonecarboxylate showed higher photochemical reactivity than methyl 3-chromonecarboxylate, in which endo adducts were yielded as major products. 相似文献
110.
Dr. Emi Uchida Dr. Kouji Sakaki Dr. Yumiko Nakamura Dr. Reiko Azumi Dr. Yuki Hirai Dr. Haruhisa Akiyama Dr. Masaru Yoshida Dr. Yasuo Norikane 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(51):17391-17397
Photoinduced phase transitions caused by photochromic reactions bring about a change in the state of matter at constant temperature. Herein, we report the photoinduced phase transitions of crystals of a photoresponsive macrocyclic compound bearing two azobenzene groups ( 1 ) at room temperature on irradiation with UV (365 nm) and visible (436 nm) light. The trans/trans isomer undergoes photoinduced phase transitions (crystal–isotropic phase–crystal) on UV light irradiation. The photochemically generated crystal exhibited reversible phase transitions between the crystal and the mesophase on UV and visible light irradiation. The molecular order of the randomly oriented crystals could be increased by irradiating with linearly polarized visible light, and the value of the order parameter was determined to be ?0.84. Heating enhances the thermal cis‐to‐trans isomerization and subsequent cooling returned crystals of the trans/trans isomer. 相似文献