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   1415篇
  免费   23篇
  国内免费   2篇
化学   996篇
晶体学   14篇
力学   10篇
数学   51篇
物理学   369篇
  2023年   6篇
  2021年   9篇
  2020年   17篇
  2019年   20篇
  2018年   12篇
  2017年   10篇
  2016年   33篇
  2015年   24篇
  2014年   28篇
  2013年   56篇
  2012年   61篇
  2011年   98篇
  2010年   49篇
  2009年   46篇
  2008年   86篇
  2007年   86篇
  2006年   74篇
  2005年   72篇
  2004年   64篇
  2003年   73篇
  2002年   79篇
  2001年   37篇
  2000年   38篇
  1999年   19篇
  1998年   19篇
  1997年   19篇
  1996年   20篇
  1995年   21篇
  1994年   15篇
  1993年   11篇
  1992年   15篇
  1991年   21篇
  1990年   16篇
  1989年   8篇
  1988年   10篇
  1987年   8篇
  1986年   13篇
  1985年   15篇
  1984年   12篇
  1983年   6篇
  1982年   12篇
  1981年   10篇
  1980年   10篇
  1979年   7篇
  1978年   9篇
  1977年   13篇
  1974年   7篇
  1973年   6篇
  1967年   6篇
  1966年   5篇
排序方式: 共有1440条查询结果,搜索用时 15 毫秒
1.
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   
2.
We prepared biodegradable poly(ethylene oxide) (PEO)/poly(L ‐lactic acid) (PLLA) graded blends by the dissolution–diffusion process, and discussed the biodegradability and tensile strength of the graded blends by comparing isotropic blend and PLLA only. All the graded blends were degraded more largely than the PLLA only and isotropic blend (PEO: 37.5 wt %), which had the same content as the total content of those graded blends. The graded blend having most excellent wide compositional gradient was degraded most largely with the enzyme. Thus, graded structure of the blends promoted their biodegradabilities large. It was considered that the dissolution of PEO with water increased the surface area attacked by the enzyme, while PEO caught PLLA oligomers to promote the biodegradation of PLLA. Then, the biodegradabilities of the graded blends were suppressed by the increasing crystallinity of PLLA. Furthermore, the strengths of all the graded blends were larger than those of the isotropic blend. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2972–2981, 2007  相似文献   
3.
A series of N-substituted 2-[(2-imidazolylsulfinyl)methyl]anilines (3) was synthesized and evaluated for its biological activity against gastric H+/K(+)-ATPase prepared from rabbit stomach and gastric acid secretions in Heidenhain pouch dogs. Monoalkyl substituents on the nitrogen atom of the aniline moiety markedly inhibited the enzyme activity to the same degree as omeprazole, a representative H+/K(+)-ATPase inhibitor. Most of these compounds, administered at 3 mg/kg i.v. inhibited histamine-stimulated gastric acid secretion. The inhibitory activity of these derivatives on the enzymes at pH 6.0 was more potent than that at pH 7.4, and was distinctly correlated to stability in aqueous solution at pH 5.0.  相似文献   
4.
5.
6.
The adhesion of Cu on Ru substrates with different crystal orientations was evaluated. The crystal orientation of sputter deposited Ru could be changed from (1 0 0) to (0 0 1) by annealing at 650 °C for 20 min. The adhesion of Cu was evaluated by the degree of Cu agglomeration on Ru. Cu films on annealed Ru films with the (0 0 1) crystal orientation showed 28% lower RMS values and 50% lower Ru surface coverage than Cu as-deposited on Ru having the (1 0 0) crystal orientation after annealing at 550 °C for 30 min, which suggest that Cu wettability on the Ru(0 0 1) was better than that on the Ru(1 0 0) plane. The low lattice misfit of 4% between Cu(1 1 1) and Ru(0 0 1) may be the reason for this good adhesion property.  相似文献   
7.
Polycrystalline (1−x)Ta2O5xTiO2 thin films were formed on Si by metalorganic decomposition (MOD) and annealed at various temperatures. As-deposited films were in the amorphous state and were completely transformed to crystalline after annealing above 600 °C. During crystallization, a thin interfacial SiO2 layer was formed at the (1−x)Ta2O5xTiO2/Si interface. Thin films with 0.92Ta2O5–0.08TiO2 composition exhibited superior insulating properties. The measured dielectric constant and dissipation factor at 1 MHz were 9 and 0.015, respectively, for films annealed at 900 °C. The interface trap density was 2.5×1011 cm−2 eV−1, and flatband voltage was −0.38 V. A charge storage density of 22.8 fC/μm2 was obtained at an applied electric field of 3 MV/cm. The leakage current density was lower than 4×10−9 A/cm2 up to an applied electric field of 6 MV/cm.  相似文献   
8.
9.
Isoprenoid-substituted phenolic compounds of moraceous plants   总被引:3,自引:0,他引:3  
  相似文献   
10.
The structures of two new bitter triterpenes, ganoderic acid A and B. isolated from a mushroom Ganoderma lucidum (FR.) Karst. (Polyporaceae) were determined as 1 and 2 on the basis of spectral data. Ganoderic acid A is a novel highly oxidized triterpene bearing a boat-shaped A-ring of lanostane.  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