全文获取类型
收费全文 | 1114篇 |
免费 | 42篇 |
国内免费 | 2篇 |
专业分类
化学 | 945篇 |
晶体学 | 9篇 |
力学 | 4篇 |
数学 | 32篇 |
物理学 | 168篇 |
出版年
2023年 | 7篇 |
2022年 | 11篇 |
2021年 | 19篇 |
2020年 | 22篇 |
2019年 | 26篇 |
2018年 | 12篇 |
2017年 | 15篇 |
2016年 | 22篇 |
2015年 | 27篇 |
2014年 | 27篇 |
2013年 | 42篇 |
2012年 | 41篇 |
2011年 | 58篇 |
2010年 | 29篇 |
2009年 | 27篇 |
2008年 | 54篇 |
2007年 | 63篇 |
2006年 | 58篇 |
2005年 | 50篇 |
2004年 | 51篇 |
2003年 | 41篇 |
2002年 | 37篇 |
2001年 | 35篇 |
2000年 | 19篇 |
1999年 | 11篇 |
1998年 | 14篇 |
1997年 | 15篇 |
1996年 | 16篇 |
1993年 | 7篇 |
1992年 | 10篇 |
1991年 | 12篇 |
1990年 | 13篇 |
1989年 | 6篇 |
1988年 | 15篇 |
1987年 | 9篇 |
1986年 | 11篇 |
1985年 | 10篇 |
1984年 | 19篇 |
1983年 | 10篇 |
1982年 | 12篇 |
1981年 | 17篇 |
1980年 | 24篇 |
1979年 | 12篇 |
1978年 | 12篇 |
1977年 | 16篇 |
1976年 | 16篇 |
1975年 | 14篇 |
1974年 | 14篇 |
1973年 | 13篇 |
1971年 | 8篇 |
排序方式: 共有1158条查询结果,搜索用时 15 毫秒
121.
Sogawa K Watanabe M Sato K Segawa S Ishii C Miyabe A Murata S Saito T Nomura F 《Analytical and bioanalytical chemistry》2011,400(7):1905-1911
In a clinical diagnosis microbiology laboratory, the current method of identifying bacterial isolates is based mainly on phenotypic
characteristics, for example growth pattern on different media, colony morphology, Gram stain, and various biochemical reactions.
These techniques collectively enable great accuracy in identifying most bacterial isolates, but are costly and time-consuming.
In our clinical microbiology laboratory, we prospectively assessed the ability of matrix-assisted laser desorption ionization–time
of flight mass spectrometry (MALDI–TOF MS) to identify bacterial strains that were routinely isolated from clinical samples.
Bacterial colonies obtained from a total of 468 strains of 92 bacterial species isolated at the Department of Clinical Laboratory
at Chiba University were directly placed on target MALDI plates followed by addition of CHCA matrix solution. The plates were
then subjected to MALDI–TOF MS measurement and the microorganisms were identified by pattern matching with the libraries in
the BioTyper 2.0 software. Identification success at the species and genus levels was 91.7% (429/468) and 97.0% (454/468),
respectively. MALDI–TOF MS is a rapid, simple, and high-throughput proteomic technique for identification of a variety of
bacterial species. Because colony-to-colony differences and effects of culture duration on the results are minimal, it can
be implemented in a conventional laboratory setting. Although for some pathogens, preanalytical processes should be refined,
and the current database should be improved to obtain more accurate results, the MALDI–TOF MS based method performs, in general,
as well as conventional methods and is a promising technology in clinical laboratories. 相似文献
122.
Transparent aqueous sols of colloidal tetramethylammonium niobate nanocrystals were synthesized by mixing tetramethylammonium hydroxide (TMAOH), niobium ethoxide, and water at TMAOH/Nb≥0.7 at room temperature. The X-ray diffraction patterns of the thin films prepared by evaporating the colloidal solutions on a glass substrate indicated that the colloidal niobate had a layered crystalline structure. Two types of layered structures are known as a layered niobate, i.e. M(4)Nb(6)O(17)·nH(2)O and MNb(3)O(8) (M=H, H(3)O, or alkaline metal). Raman spectra and electron diffraction suggested that the niobate nanocrystals were similar in crystal structure to M(4)Nb(6)O(17)·nH(2)O compounds. Moreover, when niobium oxide thin films were fabricated from the niobate colloidal solutions by the sol-gel method, oriented T-Nb(2)O(5) thin films, whose c-axis was parallel to the substrate surface, were obtained. The orientation of the thin films was probably attributed to the layered structure of the colloidal niobate nanocrystals. 相似文献
123.
Shirakawa S Terao SJ He R Maruoka K 《Chemical communications (Cambridge, England)》2011,47(38):10557-10559
Highly diastereo- and enantioselective conjugate addition of α-substituted nitroacetates to maleimides under base-free neutral phase-transfer conditions was developed for the synthesis of α,α-disubstituted α-amino acid derivatives. 相似文献
124.
Tsukamoto K Shinohara Y Iwasaki S Maeda H 《Chemical communications (Cambridge, England)》2011,47(17):5073-5075
For detection of Hg(2+) and Ag(+), we have developed a coumarin-based probe with an N'-acetylthioureido group as a novel fluorescence switch, in which the hydrogen bond formation between the N-hydrogen and the acetyl O atom markedly increases the susceptibility of the probe toward desulfurization by Hg(2+) and Ag(+). 相似文献
125.
Tsuchiya T Imai H Miyoshi S Glans PA Guo J Yamaguchi S 《Physical chemistry chemical physics : PCCP》2011,13(38):17013-17018
The electronic structure and modification of the local interatomic structure of a reactive sputtered amorphous tantalum oxide (a-TaO(x)) thin film with the variation of oxygen nonstoichiometry, x in a-TaO(x) have been investigated by X-ray absorption spectroscopy (XAS), X-ray photoemission spectroscopy (XPS), Raman scattering spectroscopy, and Rutherford back scattering spectroscopy. A parallel chemical shift of Ta4f(7/2) and O1s core levels observed with the variation of x indicates the Fermi level shift by reduction and oxidation in the framework of the rigid band model. Extended X-ray absorption fine structure (EXAFS) suggests both the increase of average coordination number of the first Ta-O shell in polyhedra and a considerable reduction of the average Ta-O bond length with the increase of x. The relative intensity of Raman shift peaks at 670 cm(-1) and 815 cm(-1), corresponding to Ta-O stretching of TaO(6) octahedra and TaO(5) probably with a pyramidal form, respectively, drastically changes between x = 2.47 to 1.86, suggesting the change in the predominant polyhedron from TaO(6) to TaO(5) with a modification in multiplicity of oxygen by the reorganization of the polyhedral network. 相似文献
126.
127.
128.
129.
130.
Thallada Bhaskar Kazuya Murai Toshiki Matsui Mihai Adrian Brebu Md. Azhar Uddin Akinori Muto Yusaku Sakata Katsuhide Murata 《Journal of Analytical and Applied Pyrolysis》2003,70(2):369-381
The thermal degradation of acrylonitrile-butadiene-styrene copolymer (ABS-Br; 10 g) containing brominated flame retardant (Br: 9.59 wt.%) was carried out at 450 °C using a semi batch operation using two different temperature programs. The heating rate was found to affect the quality of the degradation oil and yield of products (liquid, gas and residue). Data on the effect of the temperature program on the accumulation of liquid products was presented. It was found that the majority of the bromine was concentrated in the carbon residue and while majority of the nitrogen accumulates in the liquid products irrespective of degradation mode. The use of a one step constant heating rate process (I) produced a higher liquid yield (39%), than a two step process (29%). Differences were also noted in the Br and N contained in the liquids produced by the two processes. 相似文献