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   5055篇
  免费   169篇
  国内免费   15篇
化学   3683篇
晶体学   57篇
力学   76篇
数学   244篇
物理学   1179篇
  2023年   23篇
  2021年   43篇
  2020年   77篇
  2019年   87篇
  2018年   68篇
  2017年   48篇
  2016年   109篇
  2015年   107篇
  2014年   147篇
  2013年   237篇
  2012年   272篇
  2011年   314篇
  2010年   177篇
  2009年   174篇
  2008年   322篇
  2007年   334篇
  2006年   310篇
  2005年   233篇
  2004年   213篇
  2003年   198篇
  2002年   155篇
  2001年   113篇
  2000年   115篇
  1999年   78篇
  1998年   52篇
  1997年   51篇
  1996年   43篇
  1995年   52篇
  1994年   53篇
  1993年   55篇
  1992年   54篇
  1991年   50篇
  1990年   43篇
  1989年   53篇
  1988年   50篇
  1987年   44篇
  1986年   40篇
  1985年   53篇
  1984年   53篇
  1983年   51篇
  1982年   51篇
  1981年   33篇
  1980年   36篇
  1979年   54篇
  1978年   47篇
  1977年   49篇
  1976年   21篇
  1975年   28篇
  1974年   33篇
  1973年   21篇
排序方式: 共有5239条查询结果,搜索用时 19 毫秒
1.
Nonlinear Dynamics - Rectangular flat-bottom liquid tanks known as tuned liquid dampers (TLDs) are often used as passive mechanical dampers. Sloped- and triangular-bottom TLDs have been reported to...  相似文献   
2.
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   
3.
Journal of Radioanalytical and Nuclear Chemistry - Extraction chromatography flow-sheet employing octyl(phenyl)-N,N-diisobutylcarbonoylmethylphosphine oxide and bis(2-ethylhexyl) hydrogen phosphate...  相似文献   
4.
The three-dimensional structure of nanocomposite microgels was precisely determined by cryo-electron micrography. Several nanocomposite microgels that differ with respect to their nanocomposite structure, which were obtained from seeded emulsion polymerization in the presence of microgels, were used as model nanocomposite materials for cryo-electron micrography. The obtained three-dimensional segmentation images of these nanocomposite microgels provide important insights into the interactions between the hydrophobic monomers and the microgels, that is, hydrophobic styrene monomers recognize molecular-scale differences in polarity within the microgels during the emulsion polymerization. This result led to the formation of unprecedented multi-layered nanocomposite microgels, which promise substantial potential in colloidal applications.  相似文献   
5.
Endocytic pathways are practical routes for the intracellular delivery of biomacromolecules. Along with this, effective strategies for endosomal cargo release into the cytosol are desired to achieve successful delivery. Focusing on compositional differences between the cell and endosomal membranes and the pH decrease within endosomes, we designed the lipid-sensitive and pH-responsive endosome-lytic peptide HAad. This peptide contains aminoadipic acid (Aad) residues, which serve as a safety catch for preferential permeabilization of endosomal membranes over cell membranes, and His-to-Ala substitutions enhance the endosomolytic activity. The ability of HAad to destabilize endosomal membranes was supported by model studies using large unilamellar vesicles (LUVs) and by increased intracellular delivery of biomacromolecules (including antibodies) into live cells. Cerebral ventricle injection of Cre recombinase with HAad led to Cre/loxP recombination in a mouse model, thus demonstrating potential applicability of HAad in vivo.  相似文献   
6.
Shimalactones A and B are neuritogenic polyketides possessing characteristic oxabicyclo[2.2.1]heptane and bicyclo[4.2.0]octadiene ring systems that are produced by the marine fungus Emericella variecolor GF10. We identified a candidate biosynthetic gene cluster and conducted heterologous expression analysis. Expression of ShmA polyketide synthase in Aspergillus oryzae resulted in the production of preshimalactone. Aspergillus oryzae and Saccharomyces cerevisiae transformants expressing ShmA and ShmB produced shimalactones A and B, thus suggesting that the double bicyclo-ring formation reactions proceed non-enzymatically from preshimalactone epoxide. DFT calculations strongly support the idea that oxabicyclo-ring formation and 8π-6π electrocyclization proceed spontaneously after opening of the preshimalactone epoxide ring through protonation. We confirmed the formation of preshimalactone epoxide in vitro, followed by its non-enzymatic conversion to shimalactones in the dark.  相似文献   
7.
8.
One new compound, 12-epi-9-deacetoxyxenicin (1) along with a hydroperoxide product, 12-epi-9-deacetoxy-8-hydroperoxyxenicin (2) and two known sesquiterpenoids (34) were isolated from a population of Bornean soft coral Xenia sp. The structures of these secondary metabolites were elucidated based on their spectroscopic data. Compounds 1 and 2 showed cytotoxic activity against ATL cell line, S1T. In addition, compound 3 exhibited hyphal inhibition of Lagenidium thermophilum.  相似文献   
9.
10.
Minimalist photo-reactive probes, which consist of a photo-reactive group and a tag for detection of target proteins, are useful tools in chemical biology. Although several diazirine-based and aryl azide-based minimalist probes are available, no keto-based minimalist probe has yet been reported. Here we describe minimalist probes based on a 2-thienyl-substituted α-ketoamide bearing an alkyne group on the thiophene ring. The 3-alkyne probe showed the highest photo-affinity labeling efficiency.  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