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   1714篇
  免费   92篇
  国内免费   4篇
化学   1303篇
晶体学   22篇
力学   27篇
数学   92篇
物理学   366篇
  2023年   11篇
  2022年   11篇
  2021年   9篇
  2020年   27篇
  2019年   32篇
  2018年   21篇
  2017年   11篇
  2016年   45篇
  2015年   39篇
  2014年   49篇
  2013年   75篇
  2012年   103篇
  2011年   137篇
  2010年   68篇
  2009年   63篇
  2008年   125篇
  2007年   94篇
  2006年   108篇
  2005年   108篇
  2004年   99篇
  2003年   77篇
  2002年   61篇
  2001年   20篇
  2000年   20篇
  1999年   25篇
  1998年   14篇
  1997年   12篇
  1996年   18篇
  1995年   15篇
  1994年   20篇
  1993年   11篇
  1992年   22篇
  1991年   23篇
  1990年   17篇
  1989年   12篇
  1988年   14篇
  1987年   16篇
  1986年   14篇
  1985年   25篇
  1984年   14篇
  1983年   17篇
  1982年   14篇
  1981年   16篇
  1980年   13篇
  1979年   15篇
  1978年   10篇
  1977年   5篇
  1975年   5篇
  1974年   5篇
  1973年   8篇
排序方式: 共有1810条查询结果,搜索用时 593 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.
Stability Properties of Maps Between Hopf Spaces   总被引:1,自引:0,他引:1  
  相似文献   
3.
The temperature dependence of the extended X-ray absorption fine structure (EXAFS) is studied in the high Tc superconductors, YBa2Cu3O7−δ. The measurements were done at the Cu K-edge for samples of two orthorhombic phases (Tc≈90 K and ≈58 K, respectively) and a nonsuperconducting tetragonal phase. Interatomic distances and mean square relative displacements σ2 for Cu-O bonds are determined by the least squares refinement. The results indicate that values of σ2 increase near Tc for both the orthorhombic samples. It is concluded that this anomalous behavior related to Tc is caused by an anomalous vibration of oxygen atoms in the Ba-O layer. Changes in the Cu-O distances from 300 to 20 K are not found.  相似文献   
4.
Tsuyoshi Kitamura 《Tetrahedron》2004,60(43):9649-9657
Synthesis of (+)-anthramycin was examined. A pyrrolobenzodiazepine skeleton could be synthesized by reductive cyclization of pyrrolidine derivative, which was obtained by enyne metathesis. The conjugated enamide ester part of (+)-anthramycin derivative was constructed by cross-metathesis.  相似文献   
5.
The emergence of drug-resistant hepatitis B virus (HBV) has been reported in patients with prolonged administration of lamivudine, which is a potent drug for the prevention of HBV infection. Lamivudine-resistant HBV has several types of mutations at the YMDD motif of its DNA polymerase. We successfully demonstrated that monitoring the hybridization behavior in nanostructured reverse micelles enables us to detect single nucleotide polymorphisms (SNPs). With the aid of reverse micelles, a model 40-mer oligonucleotide containing a single-base substitution was clearly distinguished from the normal, complementary oligonucleotide. In addition, we extended this technique to a high-throughput analysis. The results obtained with a 96-well micro-plate reader indicated the possibility of SNPs detection toward multiple samples of patients.  相似文献   
6.
The Constraint Molecular Dynamics approach is illustrated together with calculation on different heavy ion collisions. In particular the charge-mass distribution produced in the collision 124Sn + 64Ni and 112Sn + 58Ni at 35 MeV/nucleon is discussed. By comparing the Y = (N ? Z)/A distributions for fragments produced in central collisions it results that this observable can be sensitive to the dynamic effects induced on the two systems by the different charge/mass ratio.  相似文献   
7.
8.
This paper derives a conservation law for mean waiting times in a single-server multi-class service queueing system (M X/G/1 type queue) with setup times which may be dependent on multiple customer classes and its arrival batch size by using the work decomposition property in the queueing system with vacations.  相似文献   
9.
We investigate low-temperature behaviors of a system with chirality-pair interaction on a one-dimensional lattice. In the course of the investigation, we evaluate asymptotic forms of the characteristic values of the integral equation satisfied by the Mathieu functions. It turns out that the low-temperature behavior of correlation length of the chirality-pair correlation function is different from the one for the Ising model of spin ±1 but akin to the one for the Ising model of infinite spin.  相似文献   
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