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   261篇
  国内免费   22篇
化学   3885篇
晶体学   13篇
力学   111篇
数学   666篇
物理学   663篇
  2023年   55篇
  2022年   57篇
  2021年   89篇
  2020年   110篇
  2019年   113篇
  2018年   68篇
  2017年   62篇
  2016年   225篇
  2015年   196篇
  2014年   191篇
  2013年   286篇
  2012年   367篇
  2011年   387篇
  2010年   241篇
  2009年   217篇
  2008年   313篇
  2007年   267篇
  2006年   280篇
  2005年   278篇
  2004年   241篇
  2003年   173篇
  2002年   188篇
  2001年   95篇
  2000年   82篇
  1999年   77篇
  1998年   61篇
  1997年   87篇
  1996年   69篇
  1995年   66篇
  1994年   45篇
  1993年   50篇
  1992年   32篇
  1991年   24篇
  1990年   20篇
  1989年   21篇
  1988年   14篇
  1987年   15篇
  1986年   13篇
  1985年   10篇
  1984年   10篇
  1983年   8篇
  1982年   10篇
  1981年   11篇
  1979年   7篇
  1978年   12篇
  1977年   8篇
  1976年   7篇
  1975年   8篇
  1974年   13篇
  1973年   14篇
排序方式: 共有5338条查询结果,搜索用时 15 毫秒
91.
92.
The changes in the local and global dynamics of azide-labelled lysozyme compared with that of the wild type protein are quantitatively assessed for all alanine residues along the polypeptide chain. Although attaching -N3 to alanine residues has been considered to be a minimally invasive change in the protein it is found that depending on the location of the alanine residue, the local and global changes in the dynamics differ. For Ala92, the change in the cross-correlated motions are minimal, whereas attaching -N3 to Ala90 leads to pronounced differences in the local and global correlations as quantified by the cross-correlation coefficients of the Cα atoms. We also demonstrate that the spectral region of the asymmetric azide stretch distinguishes between alanine attachment sites, whereas changes in the low frequency, far-infrared region are less characteristic.  相似文献   
93.
The radical carbohydroxylation of styrenes with aryldiazonium salts has been achieved under mild thermal conditions. A broad range of aryldiazonium salts was tolerated, and the reaction principle based on a radical–polar crossover mechanism could be extended to carboetherification as well as to a two‐step, metal‐free variant of the Meerwein arylation leading to stilbenes.  相似文献   
94.
95.
A kicked quantum nondemolition measurement is introduced, where a qubit is weakly measured by pumping current. Measurement statistics are derived for weak measurements combined with single-qubit unitary operations. These results are applied to violate a generalization of the Leggett-Garg inequality. The violation is related to the failure of the noninvasive detector assumption, and may be interpreted as either intrinsic detector backaction, or the qubit entangling the microscopic detector excitations. The results are discussed in terms of a quantum point contact kicked by a pulse generator, measuring a double quantum dot.  相似文献   
96.
We report on the first realization of a single bosonic Josephson junction, implemented by two weakly linked Bose-Einstein condensates in a double-well potential. In order to fully investigate the nonlinear tunneling dynamics we measure the density distribution in situ and deduce the evolution of the relative phase between the two condensates from interference fringes. Our results verify the predicted nonlinear generalization of tunneling oscillations in superconducting and superfluid Josephson junctions. Additionally, we confirm a novel nonlinear effect known as macroscopic quantum self-trapping, which leads to the inhibition of large amplitude tunneling oscillations.  相似文献   
97.
This report presents a new library of organometallic iridium(III) compounds of the type [Cp*IrCl(L)] (Cp*=pentamethylcyclopentadienyl and L=a functionalized β-ketoiminato ligand) showing moderate to high cytotoxicity against a range of cancer cell lines. All compounds show increased activity towards colorectal cancer, with preferential activity observed against the immortalized p53-null colorectal cell line, HCT116 p53-/-, with sensitivity factors (SF) up to 26.7. Additionally, the compounds have excellent selectivity for cancerous cells when tested against normal cell types, with selectivity ratios (SR) up to 35.6, contrary to that of cisplatin, which is neither selective nor specific for cancerous cells (SF=0.43 and SR=0.7–2.3). This work provides a preliminary understanding of the cytotoxicity of iridium compounds in the absence of p53 and has potential applications in treatment of cancers for which the p53 gene is absent or mutant.  相似文献   
98.
A range of oxobis(phenyl-1,3-butanedione) vanadium(IV) complexes have been successfully synthesized from cheap starting materials and a simple and solvent-free one-pot dry-melt reaction. This direct, straightforward, fast and alternative approach to inorganic synthesis has the potential for a wide range of applications. Analytical studies confirm their successful synthesis, purity and solid-state coordination, and we report the use of such complexes as potential drug candidates for the treatment of cancer. After a 24 hour incubation of A549 lung carcinoma cells with the compounds, they reveal cytotoxicity values elevenfold greater than cisplatin and remain non-toxic towards normal cell types. Additionally, the complexes are stable over a range of physiological pH values and show the potential for interactions with bovine serum albumin.  相似文献   
99.
<正>The generation of stretchable conductors is a mandatory precondition for the next-generation electronic devices including flexible, wearable electronics, smart skins and bioinspired devices [1–4]. This new class of electronic materials takes up external mechanical deformations and maintains structural integrity and electronic performance throughout bending, folding and stretching processes. Al-  相似文献   
100.
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