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排序方式: 共有360条查询结果,搜索用时 296 毫秒
351.
A new quassinoid, ailantinol H, was isolated from the aerial parts of Ailanthus altissima. The structure was elucidated based on spectral evidence. 相似文献
352.
Machiguchi T Okamoto J Morita Y Hasegawa T Yamabe S Minato T 《Journal of the American Chemical Society》2006,128(1):44-45
The first example of direct spectroscopic detection of transient species, 1,4-zwitterions, generated in a ketene-alkene reaction is reported. Also, a striking result of the intervention of an unprecedented "1,4-zwitterion neutral dimer" is presented in a new mechanistic pathway; the ketene-alkene reaction gives the product cyclobutanone from the initial cycloadduct alpha-methyleneoxetane. 相似文献
353.
Fujihara J Yasuda T Iida R Kimura-Kataoka K Soejima M Koda Y Kato H Panduro A Yuasa I Takeshita H 《Electrophoresis》2010,31(21):3552-3557
Several SNPs in the deoxyribonuclease I-like 1 (DNase 1L1) and DNase 1L2 were investigated. In the present study, the genotype distributions of three synonymous SNPs (V59V, rs1050095; P67P, rs1130929; A277A, rs17849495) in the DNase 1L1 gene and four non-synonymous SNPs, V122I (rs34952165), Q170H (rs6643670), and D227A (rs5987256) in the DNase 1L1 gene, as well as D197A (rs62621282) in the DNase 1L2 gene were investigated in 13 populations. In all the populations, no variation was found in four SNPs (V59V, Q170H, D227A, and A277A) in DNASE1L1 or in D197A in DNASE1L2. As for V122I, only the German population showed a low degree of polymorphism. The SNP V122I in DNASE1L1 was monoallelic for the G-allele in all of the Asian and African populations examined, with no polymorphism being evident. Since the A-allele in SNP V122I was distributed in only the Caucasian populations, not in the other ethnic groups, it was confirmed that the A-allele in SNP V122I was Caucasian-specific. On the other hand, only P67P in DNASE1L1 was polymorphic among three synonymous SNPs. The effect of nucleotide substitution corresponding to polymorphic SNP P67P on DNase 1L1 activity was examined: the corresponding nucleotide substitution in polymorphic SNP P67P has little effect on the DNase activity. 相似文献
354.
Jörgen Ekström Masataka Murakami Rosanna Inzitari Nina Khosravani Chiara Fanali Tiziana Cabras Junko Fujita‐Yoshigaki Hiorshi Sugiya Irene Messana Massimo Castagnola 《Journal of separation science》2009,32(17):2944-2952
Two peptides (MW 1211.7 and 928.5 Da) were detected by RP–HPLC–ESI–MS analysis of parotid saliva secreted upon continuous parasympathetic stimulation. The peptide with the higher mass (PSPFr‐A) corresponded to the N‐terminal dodecapeptide (Fragment 1–12) of rat parotid secretory protein (PSP), while the peptide with the lower mass (PSPFr‐B) corresponded to the 4–12 fragment of the same protein. During stimulation, the PSPFr‐A secretion increased, while the PSPFr‐B secretion decreased (HPLC–ESI–MS). In the presence of cycloheximide, PSPFr‐A was not demonstrated, while the PSPFr‐B secretion decreased. In the presence of aprotinin, the PSPFr‐B secretion was almost abolished, while the PSPFr‐A secretion increased to higher levels than those observed in the absence of the inhibitor. In vitro perfusion, with artificial solution, of stimulated rat parotid glands excluded that the fragments were derived from the circulation. Neither peptide occurred in enriched granule preparations from unstimulated glands. The results suggest that at least two pathways – granular and vesicular – are responsible for the generation of the two peptides. PSPFr‐A is the first cleavage product in both pathways. PRPFr‐B is probably generated from granular PSPFr‐A only and, at the end of the granule mediated pathway, by the action of an enzyme of the serine protease class. 相似文献
355.
Shigehito Tanahashi Kaori Segawa Meihong Zheng Junko Kuze Kazuhiko Ukai 《Optical Review》2012,19(5):345-348
The authors examined whether the perceptual reversal rate changes under monocular versus binocular viewing conditions. Our results suggest that the perceptual reversal interval increases during monocular viewing. The ratio of the reversal rate (1/interval) for the two viewing conditions (binocular/monocular) was 1.28 over a wide range of pattern luminance levels. The quoted ratio was 1.40 when the luminance was high. Such a ratio parallels the value of a well-known binocular summation index $(\sqrt 2 )$ , which was derived from the signal detection theory. The binocular summation index shows that the strength of an input signal is enhanced by binocular viewing. However, how the binocular summation shortens the perceptual reversal interval is unclear. This issue can be resolved if the perceptual reversal is derived by integrating the strength of an unconscious image signal. Thus, we discussed the mechanism of perceptual switch by associating two classical, well-studied phenomena, binocular summation and perceptual switch. 相似文献
356.
Kenichi Maruyama Yuji Mishima Keiji Minagawa Junko Motonaka 《Journal of Electroanalytical Chemistry》2001,510(1-2)
A transition metal complex as an electrochemical probe of a DNA sensor must have an applicable redox potential, high binding affinity and chemical stability. Some complexes with the dipyrido[3,2-a:2′,3′-c]phenazine (DPPZ) ligand have been reported to have high binding affinity for DNA. However, it was difficult to detect the targeted DNA electrochemically using these complexes because of the relatively high redox potential. In this work, a combination of bipyridine ligands with functional groups (---NH2, ---CH3 and ---COOH) and the DPPZ ligand were studied. The introduction of electron-donating groups was effective for controlling the redox potential of the DPPZ-type osmium complex. The [Os(DA-bpy)2DPPZ]2+ complex (DA-bpy; 4,4′-diamino-2,2′-bipyridine) had a lower half-wave potential (E1/2) of 147 mV (vs. Ag AgCl) and higher binding affinity with DNA {binding constant, K=3.1×107 M−1 in 10 mmol dm−3 Tris–HCl buffer with 50 mmol dm−3 NaCl (pH 7.76)} than those of other complexes. With the single stranded DNA (ssDNA) modified gold electrode, the hybridization signal (ΔI) of the [Os(DA-bpy)2DPPZ]2+ complex was linear in the concentration range of 1.0 pg ml−1–0.12 μg ml−1 for the targeted DNA with a regression coefficient of 0.999. The detection limit was 0.1 pg ml−1. 相似文献
357.
358.
359.
Okiko Miyata Kanami Muroya Tomoko Kobayashi Rina Yamanaka Seiko Kajisa Junko Koide Takeaki Naito 《ChemInform》2002,33(42):211-211
360.