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   1192篇
  免费   34篇
  国内免费   7篇
化学   797篇
晶体学   5篇
力学   24篇
数学   231篇
物理学   176篇
  2023年   13篇
  2022年   30篇
  2021年   32篇
  2020年   15篇
  2019年   37篇
  2018年   24篇
  2017年   25篇
  2016年   38篇
  2015年   45篇
  2014年   44篇
  2013年   93篇
  2012年   64篇
  2011年   71篇
  2010年   51篇
  2009年   54篇
  2008年   66篇
  2007年   81篇
  2006年   43篇
  2005年   32篇
  2004年   36篇
  2003年   31篇
  2002年   38篇
  2001年   18篇
  2000年   16篇
  1999年   16篇
  1998年   13篇
  1997年   14篇
  1996年   19篇
  1995年   11篇
  1994年   8篇
  1993年   5篇
  1992年   10篇
  1991年   7篇
  1990年   8篇
  1989年   7篇
  1988年   8篇
  1986年   10篇
  1985年   7篇
  1984年   6篇
  1983年   7篇
  1982年   7篇
  1981年   5篇
  1980年   4篇
  1979年   3篇
  1978年   3篇
  1975年   4篇
  1974年   3篇
  1973年   10篇
  1931年   3篇
  1903年   4篇
排序方式: 共有1233条查询结果,搜索用时 15 毫秒
991.
Correction for ‘The oxygen-resistant [FeFe]-hydrogenase CbA5H harbors an unknown radical signal’ by Melanie Heghmanns et al., Chem. Sci., 2022, 13, 7289–7294, https://doi.org/10.1039/D2SC00385F.

The authors realized that incorrect references were cited following the sentence “In conjunction with the signal''s significant width, the frequency dependence clearly indicates spin–spin interaction between the F-clusters.” The correct references are shown below as ref. 1 and 2.Additionally ref. 36 and 37 were reversed in the reference list. The correct ref. 36 is shown below as ref. 3 and the correct ref. 37 is shown below as ref. 4.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.  相似文献   
992.
Cellulose - Low moisture absorbency of hydrophobically coated flame-resistant (FR) fabrics do not correlate well with the thermophysiological comfort. In this frame, we were the first to study the...  相似文献   
993.
Despite their intrinsic hydrolysable character, imine bonds can become remarkably stable in water when self-assembled in amphiphilic micellar structures. In this work, we systematically studied some of these structures and the influence of various parameters that can be used to take control of their hydrolysis, including pH, concentration, the position of the imine function in the amphiphilic structure, relative lengths of the linked hydrophilic and hydrophobic moieties. Thermodynamic and kinetic data led us to the rational design of stable imines in water, partly based on the location of the imine function within the hydrophobic part of the amphiphile and on a predictable quantitative term that we define as the total hydrophilic–lipophilic balance (HLB). In addition, we show that such stable systems are also stimuli-responsive and therefore, of potential interest in trapping and releasing micellar components on demand.  相似文献   
994.
Gastrointestinal side effects of donepezil, including dyspepsia, nausea, vomiting or diarrhea, occur in 20–30% of patients. The pathogenesis of these dysmotility associated disorders has not been fully clarified yet. Pharmacokinetic parameters of donepezil and its active metabolite 6-O-desmethyldonepezil were investigated in experimental pigs with and without small intestinal injury induced by dextran sodium sulfate (DSS). Morphological features of this injury were evaluated by a video capsule endoscopy. The effect of a single and repeated doses of donepezil on gastric myoelectric activity was assessed. Both DSS-induced small intestinal injury and prolonged small intestinal transit time caused higher plasma concentrations of donepezil in experimental pigs. This has an important implication for clinical practice in humans, with a need to reduce doses of the drug if an underlying gastrointestinal disease is present. Donepezil had an undesirable impact on porcine myoelectric activity. This effect was further aggravated by DSS-induced small intestinal injury. These findings can explain donepezil-associated dyspepsia in humans.  相似文献   
995.
The funerary rites of particular members of the pre-Hispanic Mayan society included the pigmentation of the corpse with a red color. In order to understand this ritual, it is first necessary to identify the constituents of the pigment mixture and then, based on its properties, analyze the possible form and moment of application. In the present approach, 1H-NMR analysis was carried to detect organic components in the funerary pigments of Xcambó, a small Maya settlement in the Yucatan Peninsula. The comparison of the spectra belonging to the pigment found in the bone remains of seven individuals, and those from natural materials, led to the identification of beeswax and an abietane resin as constituents of the pigment, thus conferring it agglutinant and aromatic properties, respectively. The 1H-NMR analysis also allowed to rule out the presence of copal, a resin found in the pigment cover from paramount chiefs from the Mayan society. Additionally, a protocol for the extraction of the organic fraction from the bone segment without visible signs of analysis was developed, thus broadening the techniques available to investigate these valuable samples.  相似文献   
996.
997.
998.
999.
1000.
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