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   1148篇
  免费   26篇
  国内免费   4篇
化学   885篇
晶体学   15篇
力学   17篇
数学   59篇
物理学   202篇
  2020年   6篇
  2016年   15篇
  2015年   20篇
  2014年   14篇
  2013年   53篇
  2012年   43篇
  2011年   48篇
  2010年   20篇
  2009年   31篇
  2008年   53篇
  2007年   57篇
  2006年   78篇
  2005年   74篇
  2004年   62篇
  2003年   57篇
  2002年   53篇
  2001年   27篇
  2000年   19篇
  1999年   16篇
  1998年   16篇
  1997年   13篇
  1996年   14篇
  1995年   6篇
  1994年   9篇
  1993年   9篇
  1992年   13篇
  1991年   8篇
  1990年   12篇
  1989年   7篇
  1988年   8篇
  1987年   10篇
  1986年   17篇
  1985年   20篇
  1984年   19篇
  1983年   10篇
  1982年   28篇
  1981年   22篇
  1980年   19篇
  1979年   23篇
  1978年   19篇
  1977年   21篇
  1976年   7篇
  1975年   12篇
  1974年   15篇
  1973年   11篇
  1972年   10篇
  1971年   6篇
  1969年   4篇
  1968年   6篇
  1967年   4篇
排序方式: 共有1178条查询结果,搜索用时 15 毫秒
1.
Imanishi  Hinano  Nishimura  Takahiro  Awazu  Kunio 《Optical Review》2022,29(4):310-319
Optical Review - This paper demonstrates a method to estimate the depth of a fluorescence object in turbid media using dual-wavelength excited photodynamic diagnosis, to aid in the invasion depth...  相似文献   
2.
Cellulose derivative resin (CDR) suspensions containing resin particles of cellulose nitrate (CDR(CN)), cellulose acetate (CDR(CA)), or cellulose triacetate (CDR(CTA)) were prepared as the sorbent for resin suspension injection (RSI) electrothermal atomic absorption spectrometry (ETAAS), in which fine resin particles holding a desired trace element were directly injected into the graphite tube as the suspension. To compare the sorption ability, the distribution ratios of the Mo(VI)-phenylfluorone complex were measured between the aqueous phase and the sorbents, including the CDRs mentioned above and the finely divided anion exchange resin (AR). The results showed that the sorption ability decreases in the following order: CDR(CN) > or = AR > CDR(CA) > or = CDR(CTA). It was concluded that CDR(CN) was able to extract more than 98% of Mo(VI), and was suitable for RSI-ETAAS as well as AR. CDR(CN) was used for the determination of Mo in NIES certified reference materials, No. 10 Rice flour-unpolished; the results showed fairly good agreements between the analytical values and the certified values.  相似文献   
3.
4.
We demonstrate the potential of femtosecond two-color pulse interferometry for in vitro optical glucose monitoring, by dispersion of the group refractive index in a glucose solution sample with respect to a red-color light and a blue-color light. By comparison with femtosecond one-color pulse interferometry, the basic performance of the present system with regard to sensitivity, quantitativeness, and tolerance to surrounding disturbances, is evaluated. The resulting accuracy and precision of glucose determination are 77 and 118mg/dl for 10-mm-sample-thickness, respectively. This near-common-path configuration of the two-color pulse light provides good stability to fluctuations of sample temperature, which is important in clinical applications. Considering the performance of femtosecond two-color pulse interferometry as an optical glucose sensor, a suitable measurement site for in vivo optical glucose monitoring is discussed.  相似文献   
5.
An InGaAs/InAlAs five-layer asymmetric coupled quantum well (FACQW) is expected to show very large electrorefractive index change. n in a wideband transparency region. Band structures of the FACQW are analyzed with Luttinger-Kohn Hamiltonian. The electrorefractive characteristics of the FACQW are discussed.  相似文献   
6.
13C NMR studies showed that the population of the norcaradiene form of the title systems containing p-CH3O, H, and p-CF3 on the 7-aryl group increases in this order. The result is consistent with the prediction from the π-acceptor strength of the aryl group estimated by INDO calculations.  相似文献   
7.
Abstract— Irradiation of near-UV light in the presence of FeCl3 caused oxidation of adenosine with concomitant reduction of Fe(III) under either aerobic or anaerobic atmosphere. Major photoproducts were adenine and adenosine-5'-aldehyde, showing that oxidation took place mostly at the ribose moiety of adenosine. Detailed study showed that the reaction proceeded by the light absorption due to Fe(III) at 300-350 nm.  相似文献   
8.
We prove that a large class of self-injective algebras of tilted type is invariant under stable equivalences of module categories.

  相似文献   

9.
10.
Vinyl and methylindium ate complexes (indates) were prepared and both the tendency of immigration and regioselectivity toward cinnamyl bromide were investigated. The vinyl group was more preferably transferred than the Me group, giving a regioisomeric mixture of SN2 and SN2′ products. The ratio of SN2/SN2′ selectivity can be controlled by solvents; in the presence of polar solvents, such as N-butylpyrrolidone (NBP) and THF, the SN2′ product was mainly obtained, whereas the SN2 product was selectively prepared in solutions containing hexane. The vinylindium compound, generated by the reaction of allylic-type diindium reagents with imine, was also converted to the corresponding vinyl indate, which was allowed to react with allyl chloride to give a three-component coupling product.  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