首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   148篇
  免费   0篇
  国内免费   2篇
化学   114篇
晶体学   1篇
力学   1篇
数学   5篇
物理学   29篇
  2022年   2篇
  2021年   1篇
  2020年   1篇
  2016年   2篇
  2015年   2篇
  2014年   2篇
  2013年   8篇
  2012年   8篇
  2011年   1篇
  2010年   7篇
  2009年   5篇
  2008年   2篇
  2007年   4篇
  2006年   7篇
  2005年   5篇
  2004年   6篇
  2003年   12篇
  2002年   9篇
  2001年   3篇
  2000年   5篇
  1999年   6篇
  1997年   4篇
  1996年   2篇
  1995年   3篇
  1994年   1篇
  1993年   7篇
  1992年   2篇
  1990年   4篇
  1989年   1篇
  1988年   1篇
  1987年   2篇
  1986年   1篇
  1985年   2篇
  1984年   4篇
  1983年   1篇
  1982年   2篇
  1981年   1篇
  1980年   1篇
  1979年   1篇
  1978年   2篇
  1977年   3篇
  1976年   4篇
  1975年   2篇
  1972年   1篇
排序方式: 共有150条查询结果,搜索用时 15 毫秒
31.
Taguchi A  Mise K  Nishikubo K  Hyodo M  Shiromoto O 《Journal of voice》2012,26(5):668.e15-668.e19
Recently, the Voice Handicap Index (VHI), developed in the United States, has been highlighted as a means to assess a patient's perceptions of the severity of his or her voice disorder. The VHI is based on a self-administered questionnaire that quantifies the degree of a patient's disability related to his/her voice disorder. The questionnaire was translated into Japanese and applied to Japanese patients with various kinds of disordered voice or dysphonia. The results were analyzed and the usefulness discussed. In this study, 546 patients (281 males and 265 females) were included. Mean VHI scores were 36.2/120 in males and 44.1/120 in females. In the male patients, VHI scores were the highest among teens. However, VHI scores did not vary with age in the female patients. Patients with vocal fold paralysis, functional dysphonia, psychological dysphonia, and spasmodic dysphonia showed relatively high VHI scores, whereas those with laryngeal granuloma and laryngopharyngeal reflux disease showed low scores. In most diseases, functional and physiological scores were higher than emotional scores. In any treated patients, those with vocal nodule, vocal polyp, polypoid vocal fold, and recurrent laryngeal nerve paralysis, VHI scores decreased after therapeutic intervention. These findings suggest that the Japanese VHI is a useful tool for monitoring a patient's psychological status, choosing appropriate treatment, and assessing the therapeutic outcome.  相似文献   
32.
Solubility changes in the irradiation of copolymers bearing photoacid- or photobase-generating groups and low molecular weight photobase generators (PBGs) or photoacid generators (PAGs) were investigated. Copolymers bearing acyloxyimino (AOI) groups were used as those generating pendant amino groups photochemically. Copolymers bearing o-nitrobenzyloxycarbonyl and imino sulfonate groups were used as those generating carboxy and sulfo groups, respectively. The solubility of copolymers bearing AOI groups into polar solvents was enhanced by added PAGs such as β-keto sulfones or imino sulfonates after irradiation. A similar enhancement was observed in copolymers bearing o-nitrobenzyloxycarbonyl groups in the presence of PBGs such as oxime esters or o-nitrobenzyl carbamates. These results showed that the formation of acid–base pairs on irradiation was effective for dissolution into polar solvents. Copolymers bearing imino sulfonate groups showed a high solubility, and no such enhancement was observed by PBG. Films of copolymers bearing β-keto sulfone groups became insoluble because of crosslinking. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1708–1715, 2001  相似文献   
33.
Boron carbonitride (BCN) films have been synthesized on Si(1 0 0) substrate by radio frequency plasma enhanced chemical vapor deposition using tris-(dimethylamino)borane (TDMAB) as a precursor. The deposition was performed at the different RF powers of 400-800 W, at the working pressure of 2×10−1 Torr. The formation of the sp2-bonded BCN phase was confirmed by Fourier transform infrared spectroscopy. X-ray photoelectron spectroscopy measurements showed that B atoms were bonded to C and N atoms to form the BCN atomic hybrid configurations with the chemical compositions of B52C12N36 (sample 1; prepared at the RF power of 400 W), B52C10N38 (sample 2; at 500 W) and B46C18N36 (sample 3; at 800 W), respectively. Near-edge X-ray absorption fine structure (NEXAFS) measurements indicated that B atoms were bonded not only to N atoms but also to C atoms to form various configurations of sp2-BCN atomic hybrids. The polarization dependence of NEXAFS suggested that the predominant hybrid configuration of sp2-BCN films oriented in the direction perpendicular to the Si substrate.  相似文献   
34.
The polymers which have glyme units as alkali cation binding sites and photodimerizable cinnamoyl units were prepared by the radical polymerization of corresponding monomers. The alkali cation binding ability and selectivity of the polymers, which were studied by a method of picrate salts extraction, were strongly dependent on the length of glyme chains. When irradiated with ultraviolet light, the cinnamoyl groups caused dimerization in dilute solutions. Although the photodimerization of the polymers with relatively short glyme chains enhanced their cation binding ability, the photodimerization of the polymers bearing long glyme chains reduced their cation binding ability. The use of alkali metal cations as templates emphasized the effect of photodimerization on the cation binding properties. The effect of alkali metal cations on the quantum yields of the photodimerization of the polymers showed that two or more benzodiglyme units took part in the binding of one cation. The polymers bearing benzodiglymes, crown ethers, and cinnamoyl moieties were also prepared by the radical copolymerization of the corresponding monomers. It was found that the crown ether units of the copolymers predominantly participated in the cation binding. The photodimerization of the copolymers with suitable alkali metal cations as templates strongly enhanced their cation binding ability.  相似文献   
35.
By the reaction of α-methylaldehydes with trimethylsilylethylidenetriarylphosphoranes the introduction of vinyl group is effected in highly Cram-selective manner.  相似文献   
36.
Square-planar complexes with the formula [Pt(L(2))(L(1))](X)(2) x nH(2)O, where L(1) is S-2-aminomethylpyrrolidine (S-pyrda) or 2-aminomethylpiperidine (pipda) and L(2) is diammine (X=Cl), cyclobutane-1,1-dicarboxylato (cbdca) (X=none), 2,2'-bipyridine (bpy) (X=NO(3)), or 1,10-phenanthroline (phen) (X=Cl), were prepared and the nature of the coordination of L(1) was examined by (1)H-NMR spectroscopy and X-ray crystallography. These 2-aminomethylazacycloalkane derivatives form five-membered chelate rings condensed with an azacycloalkane ring in cis- or trans-configurations. The (1)H-NMR spectrum of complexes with S-pyrda as L(1) were consistent with cis-condensed rings in an S(N) conformation with any of L(2) group. However, (1)H-NMR spectra of the complexes with pipda as L(1) indicated trans-fused successive rings for the diammine and cbdca as L(2), but spectra for bpy and phen as L(2) were consistent with a conformation having cis-fused successive rings. X-Ray crystallography data for the two complexes with pipda as L(1) and cbdca (1) and bpy (2) as L(2) confirms the different coordination behavior in the solid state.  相似文献   
37.
Photocrosslinkable systems with thermally cleavable properties based on blends of poly(vinyl phenol) (PVP) and diepoxides were investigated. Thermally cleavable diepoxides as crosslinkers were prepared and characterized. As a thermally cleavable linkage, a tertiary ester moiety was incorporated into the crosslinker molecule. PVP/crosslinker blended films containing photoacid generators (PAGs) became insoluble in solvents after UV irradiation and subsequent post‐exposure‐bake (PEB) treatment. With a rise in the PEB temperature, the insoluble fraction of the irradiated films increased, passed through a maximum value, decreased, and increased again at elevated baking temperatures. The insolubilization profiles of the irradiated films were complicated and strongly dependent on the type of PAG used, the structure of the crosslinkers, and the PVP/crosslinker ratio. A mechanism for the thermal degradation was studied with Fourier transform infrared spectroscopy. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3055–3062, 2002  相似文献   
38.
We have designed, synthesized and evaluated dibenzothiophenylacetylene homologues as new heterocyclic molecules which were expected to have high δα values and short wavelength UV absorption spectra. The dibenzothiophenyl acetylene homologues exhibited wide nematic phase ranges and had very high extrapolated δn of over 0.6 and directly measured values of 0.5. The compounds with two dibenzothiophenyl rings were colourless, so that we have succeeded in obtaining colourless super-high δn liquid crystals. We have also analysed the contribution of the transition band to the refractive indices and the birefringence. From the analysis, the main origins of δn for compounds 1 and 2 are lower MOs than the HOMO and this results in the compatibility of large δn and lack of colour. The dibenzothiophenylacetylene compounds behaved according to our design expectations.  相似文献   
39.
Although there have been some reports about the cytotoxic effects of photodynamic therapy (PDT) on multidrug-resistant bacteria, there have been few reports in which favorable results of PDT on a local infection site are described. This study aimed to verify the hypothesis that the low efficacy of PDT on a local infection site is due to the cytotoxic effect of PDT on leukocytes. PDT using Photofrin® exerted significant cytotoxicity for cultured methicillin-resistant Staphylococcus aureus (MRSA). Nevertheless, this therapeutic modality was not effective for a murine MRSA arthritis model. Approximately 30% of intra-articular leukocytes, mainly neutrophils, died immediately after PDT, and a further decrease in the number of intra-articular leukocytes and atrophy of the synovial tissue were seen 24 h after PDT. Isolated peripheral neutrophils showed significant affinity for Photofrin® and showed significant morphological damage, resulting in cell death, when they were subject to PDT using Photofrin®. These results indicate that intra-articular neutrophils have an influence on the effects of PDT for MRSA arthritis.  相似文献   
40.
Collagen model peptide (Pro-Pro-Gly)10 has a triple helical structure and undergoes a thermal transition to a single random coil structure. The transition temperature of the analogous model peptides depends largely on amino acid substitution. Substitution of Pro by 4-hydroxyproline (Hyp) or 4-fluoroproline (fPro) has especially attracted attention because the position of substitution and chirality of the hydroxyl group or fluorine atom affect the transition temperatures. Here, we demonstrated that (4(S)-fPro-Pro-Gly)10 takes a triple helical structure, but (4(R)-fPro-Pro-Gly)10 exists in a single chain structure. This is not consistent with the case of Hyp substitution in our previous report where both (4(S)-Hyp-Pro-Gly)10 and (4(R)-Hyp-Pro-Gly)10 are in a single random coil state.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号