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   288篇
  免费   1篇
  国内免费   1篇
化学   122篇
晶体学   1篇
力学   19篇
数学   55篇
物理学   93篇
  2021年   2篇
  2020年   3篇
  2018年   3篇
  2017年   5篇
  2016年   6篇
  2015年   2篇
  2014年   7篇
  2013年   8篇
  2012年   4篇
  2011年   10篇
  2010年   8篇
  2009年   9篇
  2008年   12篇
  2007年   13篇
  2006年   14篇
  2005年   9篇
  2004年   8篇
  2003年   11篇
  2002年   13篇
  2001年   12篇
  2000年   4篇
  1999年   5篇
  1998年   7篇
  1997年   4篇
  1996年   7篇
  1995年   4篇
  1994年   3篇
  1993年   4篇
  1992年   3篇
  1991年   4篇
  1990年   2篇
  1989年   9篇
  1988年   5篇
  1987年   8篇
  1986年   5篇
  1985年   2篇
  1984年   9篇
  1983年   4篇
  1982年   5篇
  1980年   4篇
  1977年   5篇
  1975年   2篇
  1973年   2篇
  1972年   1篇
  1971年   4篇
  1969年   3篇
  1968年   2篇
  1967年   4篇
  1966年   2篇
  1962年   1篇
排序方式: 共有290条查询结果,搜索用时 15 毫秒
1.
This paper discusses monitoring electromagnetic fields (natural and artificial) in the atmosphere. Methods are described for remote sensing of the atmosphere and surface in order to examine static and alternating electromagnetic-energy fluxes in the biosphere.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 69–79, December, 1991.  相似文献   
2.
3.
A preparative method has been developed and the synthesis has been effected of anilides and heterylamides of 4-hydroxy-6-methyl-2-oxo-1-propyl-1,2,5,6,7,8-hexahydroquinoline-3-carboxylic acid. A comparative analysis has been carried out of the structure and antitubercular properties of the synthesized compounds and their analogs unsubstituted in the quinoline nucleus. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 405–414, March, 2007.  相似文献   
4.
The composition of the various groups of liposoluble compounds in the leaves of wild cabbage of early-, middle-, and late-ripening varieties have been identified and their amounts have been determined by chromatographic and chemical methods. About 30 groups of lipid substances have been identified, among which free and esterified forms of sterols, di- and triacylglycerols, hydrocarbons, lipoquinones, mono- and digalactoside glycerides, cerebrosides, phosphatidylethanolamines, phosphatidylglycerols, and phosphatidylcholines predominate. The presence of 13 components has been established among the fatty acids, linolenic acid being present in the greatest amount (50%). The influence of the time of ripening of the cabbage variety (early-, middle-, or late-ripening) on the composition of the lipid complex has been elucidated.M. V. Lomonosov Technological Institute of the Food Industry, Odessa. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 180–185, March–April, 1989.  相似文献   
5.
The reaction of dibenzylphosphine oxide with O-methyloximes of some ,-unsaturated ketones results in the phosphorylation at the -carbon atom to form methoxyiminophosphine oxides, whereas the reaction of dibenzylphosphine oxide with O-methyloximes of ,-unsaturated aldehydes affords aminodihydrophosphole oxides.  相似文献   
6.
The qualitative and quantitative compositions of the grape and its component parts — flesh, skin, seeds — have been studied. Ten fractions have been identified, the main ones being cerebrosides and monogalactosyldiglycerides. The compositions of the fatty acids, of the sphingosine bases, of the sterols, and of the carbohydrates of the individual fraction of phytoglycolipids have been determined.Physicochemical Institute of the Academy of Sciences of the Ukrainian SSR, Odessa. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 296–300, May–June, 1984.  相似文献   
7.
The use of a small precolumn instead of an injection loop for the determination of a new phytochemical drug, fellavine, and its metabolites is described. The method combines the direct injection of plasma and urine into the reversed-phase precolumn with separation on a Spheri-5 RP-18 analytical column. Different sorbents in the precolumn were compared. A recovery of fellavine and its metabolites from biological fluids except rat plasma of almost 100% was achieved on Chrompack RP (30-40 microns) and LiChrosorb RP-18 (7 microns). For rat plasma only the last sorbent gave 80% fellavine recovery. The influence of the protein binding on the fellavine recovery was examined. The limit of detection was equal to 0.05 micrograms/ml fellavine for plasma and 0.02 micrograms/ml for urine. To enhance the limit of detection longer precolumns were perferred.  相似文献   
8.
A convenient procedure has been proposed for the synthesis ortho-vinylbenzyl-substituted ethers, amines, and sulfides via reaction of o-(2-bromoethyl)benzyl bromide with various nucleophiles.  相似文献   
9.
The linear viscoelastic behavior in dynamic shear and tensile creep at temperatures from −30 to 70 °C is measured for an styrene–butadiene rubber (SBR) elastomer cured with dicumyl peroxide to crosslinking densities between 0 and 23.5 × 10−5 mol/cm3. The G′, G″, and tan δ isotherms are analyzed by time–temperature superposition (TTS), where the tan δ master curves are consistent with those of Mancke and Ferry. However, to achieve the TTS in the lightly crosslinked SBR systems, an anomalous vertical shift is required in the narrow temperature region from 10 to 30 °C. The vertical shift factor in this temperature region is not the standard from rubber elasticity. No anomalous behavior is detected in the equilibrium modulus, which is a linear function of temperature in accordance with the classical theory of rubber elasticity. In contrast to SBR, standard vertical shifts are required to effect TTS for uncrosslinked polybutadiene and an ethylene propylene diene monomer elastomer. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013  相似文献   
10.
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