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   976篇
  免费   29篇
  国内免费   5篇
化学   747篇
晶体学   10篇
力学   11篇
数学   59篇
物理学   183篇
  2023年   6篇
  2022年   8篇
  2021年   7篇
  2020年   13篇
  2019年   12篇
  2018年   15篇
  2017年   12篇
  2016年   16篇
  2015年   15篇
  2014年   22篇
  2013年   46篇
  2012年   53篇
  2011年   47篇
  2010年   30篇
  2009年   33篇
  2008年   52篇
  2007年   38篇
  2006年   55篇
  2005年   73篇
  2004年   55篇
  2003年   46篇
  2002年   53篇
  2001年   18篇
  2000年   19篇
  1999年   14篇
  1998年   11篇
  1997年   12篇
  1996年   15篇
  1995年   9篇
  1994年   11篇
  1993年   7篇
  1992年   14篇
  1991年   8篇
  1990年   9篇
  1989年   12篇
  1988年   5篇
  1987年   10篇
  1986年   12篇
  1985年   16篇
  1984年   13篇
  1983年   10篇
  1982年   14篇
  1981年   10篇
  1979年   6篇
  1978年   12篇
  1976年   5篇
  1974年   4篇
  1973年   5篇
  1968年   4篇
  1967年   5篇
排序方式: 共有1010条查询结果,搜索用时 15 毫秒
41.
The first dimesitylboryl substitution of aryl halides with a silylborane bearing a dimesitylboryl group in the presence of alkali‐metal alkoxides is described. The reactions of aryl bromides or iodides with Ph2MeSi?BMes2 and Na(OtBu) afforded the desired aryl dimesitylboranes in good to high yields and with high borylation/silylation ratios. Selective reaction of the sterically less‐hindered C?Br bond of dibromoarenes provided monoborylated products. This reaction was used to rapidly construct a D‐π‐A aryl dimesityl borane with a non‐symmetrical biphenyl spacer.  相似文献   
42.
We are developing a daily health monitoring system that uses mobile phones with cameras and analyzes physiological conditions from R, G, and B intensity levels. However, since it is affected by various imaging conditions of the image input, color correction is required for accurate health monitoring. Therefore, we developed and validated a colorcorrection algorithm to derive reliable color information by correcting the spectral reflectance using the Wiener estimation and a color chart.  相似文献   
43.
Recent process optimization allows improving homogeneity and a significant increase of Jc in GdBa2Cu3O7-δ deposited on ion-beam assisted deposited MgO template (GdBCO/IBAD-MgO). We applied low-temperature laser scanning microscopy and laser scanning thermo-electric microscopy (LSTEM) to investigate local dissipation and defects simultaneously in recent GdBCO/IBAD-MgO coated conductor. By using high-resolution LSTEM, we could detect current blocking obstacles which are responsible for the large scale local dissipation. Data on the present GdBCO/IBAD-MgO coated conductors point out a significant reduction of current blocking obstacles compared to the previous process. We have shown the improvement of spatial homogeneity in the recent GdBCO/IBAD-MgO coated conductors. Current blocking obstacles are much less densely distributed as compared to previous YBCO/IBAD-GZO coated conductor. Obstacles larger than several micrometer significantly increase local dissipation whereas smaller defects do not influence it noticeably. 2D map of the phase delay component of the thermoelectric voltage lock-in signal is effective to analyze current blocking obstacles having action upon local dissipation.  相似文献   
44.
45.
Pinacol-type coupling reaction products presenting a high meso-diastereoselectivity (the ratio dl/meso was 4/96 up to 1/99) were obtained in fair to good yields (24–69%) using several aromatic aldehydes as starting materials and aluminium powder/copper sulfate as catalysts, in water, under reflux conditions.  相似文献   
46.
α-Trifluoromethyl chalcones were prepared and evaluated for their antiproliferative activities against androgen-independent prostate cancer cell lines as well as five additional types of human tumor cell lines. The most potent chalcone 5 showed superior antitumor activity in vivo with both oral and intraperitoneal administration at 3 mg/kg. Cell-based mechanism of action studies demonstrated that 5 induced cell accumulation at sub-G1 and G2/M phases without interfering with microtubule polymerization. Furthermore, several cancer cell growth-related proteins were identified by using chalcone 5 as a bait for the affinity purification of binding proteins.  相似文献   
47.
Optical Review - To quantify the changes in optical properties of in vivo rat liver tissue, we applied diffuse reflectance spectroscopy (DRS) system using single-reflectance fiber probe during...  相似文献   
48.
Optical Review - To evaluate multi-spectral images of the absorption and scattering properties in the cerebral cortex of rat brain, we investigated spectral reflectance images estimated by the...  相似文献   
49.
50.
UDP‐glucose:glycoprotein glucosyltransferase (UGGT) plays a key role in recognizing folded and misfolded glycoproteins in the glycoprotein quality control system of the endoplasmic reticulum. UGGT detects misfolded glycoproteins and re‐glucosylates them as a tag for misfolded glycoproteins. A flexible model to reproduce in vitro folding of a glycoprotein in the presence of UGGT in a mixture containing correctly folded, folding intermediates, and misfolded glycoproteins is described. The data demonstrates that UGGT can re‐glucosylate all intermediates in the in vitro folding experiments, thus indicating that UGGT inspects not only final folded products, but also the glycoprotein folding intermediates.  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