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   13868篇
  免费   1105篇
  国内免费   378篇
  2023年   98篇
  2022年   219篇
  2021年   346篇
  2020年   273篇
  2019年   337篇
  2018年   382篇
  2017年   324篇
  2016年   440篇
  2015年   671篇
  2014年   730篇
  2013年   885篇
  2012年   1046篇
  2011年   969篇
  2010年   600篇
  2009年   480篇
  2008年   708篇
  2007年   680篇
  2006年   625篇
  2005年   556篇
  2004年   503篇
  2003年   499篇
  2002年   418篇
  2001年   342篇
  2000年   336篇
  1999年   288篇
  1998年   130篇
  1997年   97篇
  1996年   87篇
  1995年   71篇
  1994年   91篇
  1993年   68篇
  1992年   171篇
  1991年   154篇
  1990年   136篇
  1989年   160篇
  1988年   128篇
  1987年   119篇
  1986年   113篇
  1985年   106篇
  1984年   77篇
  1983年   79篇
  1982年   62篇
  1981年   45篇
  1979年   63篇
  1977年   79篇
  1976年   51篇
  1975年   45篇
  1974年   57篇
  1969年   43篇
  1968年   46篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
82.
Summary The authors examined 734 sensitised patients living in four localities in Liguria (Genoa, Savona, Pietra Ligure and Sanremo). The commonest source of sensitisation (62.7%) was Urticaceae (Parietaria), followed by Poaceae (52.5%) andOlea europaea L. (24.0%). A survey of airborne pollens revealed a greater presence of Urticaceae and Poaceae in Genoa and of Oleaceae in Pietra Ligure and Sanremo.  相似文献   
83.
84.
85.
Spontaneous fluctuations in heart rate were analyzed by spectral analysis in the ether anesthetized and pithed adult rat. In order to investigate the changes in the spectral pattern of the fluctuations, the selective 5HT-2 and -3 isoreceptor blockers ritanserin and BRL 43694A were used. In both the experimental conditions, ritanserin blockade led to dose-dependent increased fluctuations in HR low and high frequencies. In both the anesthetized and pithed rats, the low frequency range HR fluctuations were drastically reduced by BRL 43694A.  相似文献   
86.
The presence of inflammatory reaction, plasma cells, and eosinophils in peritumoral connective tissue and in neoplastic stroma was evaluated with morphometrical method in 181 patients affected by laryngeal carcinoma. A logistic multiple regression model was applied making it with the use of an independent variable represented by the "infiltrating" or "expansive" types of tumor growth, in order to evaluate the probability of nodal metastatsis of each parameter. The results suggest an inverse correlationship between plasma cells and inflammatory infiltration and incidence of nodal metastatsis only in the comparison of the extreme conditions: those with scarce infiltration versus the ones with large infiltration. Inflammatory or plasmacellular infiltration may represent both a defense mechanism against cancer and an aspecific or allergic reaction. The eosinophilic infiltration shows no value in the prevention of nodal involvement.  相似文献   
87.
88.
Summary Pleurotus florida was grown in submerged culture with different concentrations of sugar beet pulp with a view to its nutritional upgrading. Micelial growth, protein enrichment and dry weight loss of the solid residues of cultures, as well as the evolution of reducing sugars in the liquid medium, were followed for 14 days. A product with 45% (w/w) protein and a saccharification extent as high as 35% (w/w) were obtained after 7 days with 1% (w/v) sugar beet pulp.  相似文献   
89.
90.
Human erythrocyte glucose-6-phosphate dehydrogenase contains a reactive lysyl residue, which can be labelled with pyridoxal 5'-phosphate. The binding of one mole of pyridoxal 5'-phosphate per mole of enzyme subunit produces substantial inactivation. The substrate glucose-6-phosphate prevents the loss of activity, suggesting that the reaction site is close to the substrate-binding site. A tryptic peptide containing the pyridoxal-5'-phosphate-binding lysyl residue has been isolated and characterised. The reactive lysyl residue has been identified in the glucose-6-phosphate dehydrogenase amino acid sequence. Comparison with glucose-6-phosphate dehydrogenase from other sources shows a high homology with a peptide containing a reactive lysyl residue, isolated from the enzyme from Saccharomyces cerevisiae; glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides also contains a region highly homologous with the sequence around the reactive lysyl residue in the human enzyme. The results of this communication provide the first direct evidence for the association of an essential catalytic function with a specific region of the molecule of human erythrocyte glucose-6-phosphate dehydrogenase.  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