全文获取类型
收费全文 | 379篇 |
免费 | 1篇 |
国内免费 | 4篇 |
专业分类
化学 | 214篇 |
晶体学 | 3篇 |
力学 | 2篇 |
数学 | 9篇 |
物理学 | 156篇 |
出版年
2022年 | 2篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2015年 | 3篇 |
2014年 | 2篇 |
2013年 | 13篇 |
2012年 | 13篇 |
2011年 | 15篇 |
2010年 | 6篇 |
2009年 | 7篇 |
2008年 | 21篇 |
2007年 | 37篇 |
2006年 | 31篇 |
2005年 | 42篇 |
2004年 | 36篇 |
2003年 | 22篇 |
2002年 | 25篇 |
2001年 | 10篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 7篇 |
1988年 | 2篇 |
1987年 | 8篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 6篇 |
1977年 | 1篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 3篇 |
1968年 | 3篇 |
1967年 | 1篇 |
排序方式: 共有384条查询结果,搜索用时 15 毫秒
321.
A wide range of dimethyl 2-(5-aryl-5-oxopentyl)malonates was electrooxidized in methanol, in the presence of catalytic amount of potassium iodide, to give the corresponding dimethyl 2-aroylcyclopentane-1,1-dicarboxylates in high yields. 相似文献
322.
Hitoshi Sakai Hisahiro Haglwara Takashi Hoshi Toshio Suzuki Masayoshi Ando 《合成通讯》2013,43(12):2035-2042
Kinetically generated enolate of cyclohexenone when reacted with methyl 2, 3-dichloropropanoate provided methyl tricyclo-[3. 2. 1. 02, 7]octane-l-carboxylate and its congeners via domino Michael-Michael-alkylation reaction. 相似文献
323.
Shinnosuke Nishikawa Haruki Yamamori Kousuke Ohashi Masayuki Hoshi Takashi Yoshida 《合成通讯》2013,43(13):1766-1771
Several ketone N-phenylsemicarbazones were electrooxidized in the presence of potassium iodide and a base using methanol as the solvent to give nearly commensurate amounts of methyl N-phenylcarbamate and the corresponding dimethyl acetals. Continuous evolution of gaseous nitrogen was observed from the anolyte during the electrooxidation. The reactions were carried out under very mild reaction conditions and are presumed to proceed through a four-electron oxidation process, in which the iodide ion plays an important role as an electron carrier. 相似文献
324.
Fumiko Yoshii Tomoko Nakamura Shuichi Hirono Yumiko Shimizu Takashi Hoshi Masayoshi Ando Hisahiro Hagiwara 《Helvetica chimica acta》2001,84(7):2051-2063
The selection of odor‐active conformers and the construction of a model for a targeted odor type, i.e., for the lily‐of‐the‐valley odor, were examined. The disagreement of the odors of 1,3,4,5‐tetrahydro‐2‐benzoxepin derivative 1 and 3‐[4‐(tert‐butyl)phenyl]‐2‐methylpropanal ( 2 ) is discussed in terms of their stable conformers. The conformer active for the lily‐of‐the‐valley odor was investigated by conformational analyses of several related compounds. Based on the integrated model consisting of the assumed active conformers (Fig. 5), compounds anticipated to possess the lily‐of‐the‐valley odor were designed and synthesized. The odor of synthetic 7‐(tert‐butyl)‐1,2,4,5‐tetrahydro‐3H‐benzocyclohepten‐3‐one ( 8 ) and 3‐[4‐(tert‐butyl)phenyl]cyclopentanone ( 13 ) were evaluated by perfumers to have a floral odor and to recall the lily‐of‐the‐valley and lilac odors, respectively. Our methodology to design new odoriferous compounds, based on conformational analysis, selection of odor‐active conformers, and construction of a model, proved to be satisfactory. 相似文献
325.
M. Yamamoto M. Hoshi J. Takada A. Kh. Sekerbaev B. I. Gusev 《Journal of Radioanalytical and Nuclear Chemistry》1999,242(1):63-74
Field missions were sent to Semipalatinsk City and several settlements near the former Semipalatinsk nuclear test site to
investigate the current radioactive contamination levels of the land coming from long-lived radionuclides. The soil was sampled
at about 20 sites, including some settlements such as Mostik, Dolon and Chagan, forest and pasture areas, along the roads
from Semipalatinsk City to Kurchatov City and to Korosteli settlement in the direction of the Altai District. The radioactivities
of137Cs,238Pu and239,240Pu as well as240Pu/239Pu atomic ratios in the soil were determined by non-destructive γ-ray spectrometry and radiochemical separation followed by
α-ray spectrometry and/or ICP-MS, respectively. The results showed a distinction of137Cs and239,240Pu inventories in soil depending on the site where we visited. While the overall137Cs levels were as same as or slightly lower than the domestic global fallout level (3·103–7·103 Bq/m2),239,240Pu levels at some sites were several to a few ten times higher than the domestic level (40–120 Bq/m2). The atomic ratios of240Pu/239Pu in the soil were in the range of 0.024–0.125, which were significantly lower than the value of 0.18 commonly accepted for
global fallout Pu. 相似文献
326.
H. Mimura H. Hoshi K. Akiba Y. Onodera 《Journal of Radioanalytical and Nuclear Chemistry》2001,247(2):375-379
Microcapsules enclosing an extractant with strong affinity for Am were prepared by employing a biopolymer gel as an immobilization matrix. A relatively large separation factor between Am and Eu was exhibited by the microcapsule containing of bis(2,4,4-trimethylpentyl)dithiophosphinic acid (Cyanex 301, HA) and alginic acid (HALG). The chromatographic separation of these metal ions was accomplished by gradient elution through the column packed with HA-HALG. 相似文献
327.
We consider the solution of complex symmetric shifted linear systems. Such systems arise in large scale electronic structure theory and there is a strong need for the fast solution of the systems. In this paper, we describe an algorithm for solving the systems, which is based on the QMR_SYM method for solving complex symmetric linear systems. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
328.
Masato Hoshi Koichi Kikuchi Hiroshi Kokubun 《Journal of photochemistry and photobiology. A, Chemistry》1987,41(1)
The rate constants and the radical yields for the hydrogen-atom transfer reaction from four monohalogenated phenols to triplet 7,8-benzoquinoline were determined by an emission—absorption flash technique. The rate constants are of the order of 109 M−1 s−1 except for 2-bromophenol, and the radical yield Φrt decreases on halogen substitution. In the case of monobromophenols, Φrt is sensitive to the position of the bromine atom. The rate constant of free radical recombination increases with decreasing Φrt. Such heavy-atom effects are explained in terms of the heavy-atom-induced spin relaxation of the triplet radical pair. 相似文献
329.
T Ohnishi H Hoshi S Jinnouchi S Nagamachi H Yoshimura S Futami K Watanabe 《Radioisotopes》1989,38(7):305-310
The usefulness of IMP-SPECT and rCBF image by 133Xe inhalation method on rCBF in patients with moyamoya disease was studied. Six patients with moyamoya disease were diagnosed by cerebral angiogram, and STA-MCA anastomosis technique and EMS were done to reconstruct the rCBF. Low perfusion areas were detected around the cerebral infarction and hemorrhage and that of anterior and middle cerebral arteries by IMP-SPECT and 133Xe-rCBF image met by X-ray CT. After surgery, 4 out of 6 cases showed the improvement of rCBF by IMP-SPECT and 133Xe-rCBF image, as for clinical symptoms, there were reduction of TIA in 3 cases, and no rehemorrhage in 3 cases. In summary IMP-SPECT and 133Xe-rCBF image may be useful method to evaluate the rCBF in moyamoya disease and the change of rCBF post STA-MCA anastomosis technique and EMS. 相似文献
330.