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   800篇
  免费   13篇
  国内免费   3篇
化学   446篇
晶体学   11篇
力学   34篇
数学   125篇
物理学   200篇
  2021年   6篇
  2020年   8篇
  2019年   11篇
  2018年   7篇
  2017年   8篇
  2016年   19篇
  2015年   16篇
  2014年   23篇
  2013年   44篇
  2012年   39篇
  2011年   38篇
  2010年   24篇
  2009年   24篇
  2008年   42篇
  2007年   41篇
  2006年   24篇
  2005年   35篇
  2004年   39篇
  2003年   27篇
  2002年   38篇
  2001年   17篇
  2000年   15篇
  1999年   6篇
  1998年   8篇
  1997年   9篇
  1996年   14篇
  1995年   15篇
  1994年   18篇
  1993年   12篇
  1992年   18篇
  1991年   12篇
  1990年   7篇
  1989年   7篇
  1988年   7篇
  1987年   6篇
  1986年   10篇
  1985年   9篇
  1983年   8篇
  1982年   6篇
  1981年   11篇
  1980年   6篇
  1979年   7篇
  1978年   15篇
  1977年   4篇
  1976年   8篇
  1974年   8篇
  1972年   9篇
  1969年   3篇
  1968年   4篇
  1964年   3篇
排序方式: 共有816条查询结果,搜索用时 15 毫秒
1.
2.
Despite slow ongoing progress in increasing the representation of women in academia, women remain significantly under-represented at senior levels, in particular in the natural sciences and engineering. Not infrequently, this is downplayed by bringing forth arguments such as inherent biological differences between genders, that current policies are adequate to address the issue, or by deflecting this as being “not my problem” among other examples. In this piece we present scientific evidence that counters these claims, as well as a best-practice example, Genie, from Chalmers University of Technology, where one of the authors is currently employed. We also highlight particular challenges caused by the current COVID-19 pandemic. Finally, we conclude by proposing some possible solutions to the situation and emphasize that we need to all do our part, to ensure that the next generation of academics experience a more diverse, inclusive, and equitable working environment.  相似文献   
3.
This study aims at evaluating the capabilities of synchrotron radiation micro X-ray fluorescence spectrometry (SR micro-XRF) for qualitative and semi-quantitative elemental mapping of the distribution of actinides in human tissues originating from individuals with documented occupational exposure. The investigated lymph node tissues were provided by the United States Transuranium and Uranium Registries (USTUR) and were analyzed following appropriate sample pre-treatment. Semi-quantitative results were obtained via calibration by external standards and demonstrated that the uranium concentration level in the detected actinide hot spots reaches more than 100 μg/g. For the plutonium hot spots, concentration levels up to 31 μg/g were found. As illustrated by this case study on these unique samples, SR micro-XRF has a high potential for this type of elemental bio-imaging owing to its high sensitivity, high spatial resolution, and non-destructive character.
?
Graphical Abstract SR micro-XRF study of the distribution of actinitides in human tissues. Left Location of the U-contaminated tissue sample in the human body. Middle U distribution derived from the high resolution SR micro-XRF scan on the tissue sample, indication of five U hot spots. Right Detail of the point measurement spectrum of U hot spot 3, intense U-Lα fluorescence peak located at 13.6 keV.
  相似文献   
4.
5.
6.
This paper is intended as a tutorial review on the use of inductively coupled plasma – tandem mass spectrometry (ICP-MS/MS) for the interference-free quantitative determination and isotope ratio analysis of metals and metalloids in different sample types. Attention is devoted both to the instrumentation and to some specific tools and procedures available for advanced method development. Next to the more typical reaction gases, e.g., H2, O2 and NH3, also the use of promising alternative gases, such as CH3F, is covered, and the possible reaction pathways with those reactive gases are discussed. A variety of published applications relying on the use of ICP-MS/MS are described, to illustrate the added value of tandem mass spectrometry in (ultra)trace analysis.  相似文献   
7.
Exposure of DNA to endo- and exogenous DNA binding chemicals can result in the formation of DNA adducts and is believed to be the first step in chemically induced carcinogenesis. DNA adductomics is a relatively new field of research which studies the formation of known and unknown DNA adducts in DNA due to exposure to genotoxic chemicals. In this study, a new UHPLC-HRMS(/MS)-based DNA adduct detection method was developed and validated. Four targeted DNA adducts, which all have been linked to dietary genotoxicity, were included in the described method; O6-methylguanine (O6-MeG), O6-carboxymethylguanine (O6-CMG), pyrimidopurinone (M1G) and methylhydroxypropanoguanine (CroG). As a supplementary tool for DNA adductomics, a DNA adduct database, which currently contains 123 different diet-related DNA adducts, was constructed. By means of the newly developed method and database, all 4 targeted DNA adducts and 32 untargeted DNA adducts could be detected in different DNA samples. The obtained results clearly demonstrate the merit of the described method for both targeted and untargeted DNA adduct detection in vitro and in vivo, whilst the diet-related DNA adduct database can distinctly facilitate data interpretation.  相似文献   
8.
Fuchs  Lynn  Fuchs  Douglas  Seethaler  Pamela M.  Barnes  Marcia A. 《ZDM》2020,52(1):87-96
ZDM – Mathematics Education - The focus of this article is the well documented association between low working memory capacity and difficulty with mathematical word-problem solving. We begin...  相似文献   
9.
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