全文获取类型
收费全文 | 1196篇 |
免费 | 156篇 |
出版年
2021年 | 11篇 |
2018年 | 12篇 |
2016年 | 24篇 |
2015年 | 30篇 |
2014年 | 54篇 |
2013年 | 66篇 |
2012年 | 56篇 |
2011年 | 49篇 |
2010年 | 31篇 |
2009年 | 40篇 |
2008年 | 42篇 |
2007年 | 37篇 |
2006年 | 42篇 |
2005年 | 42篇 |
2004年 | 41篇 |
2003年 | 35篇 |
2002年 | 37篇 |
2001年 | 42篇 |
2000年 | 34篇 |
1999年 | 33篇 |
1998年 | 24篇 |
1997年 | 17篇 |
1996年 | 16篇 |
1995年 | 13篇 |
1994年 | 20篇 |
1993年 | 14篇 |
1992年 | 24篇 |
1991年 | 21篇 |
1990年 | 15篇 |
1989年 | 18篇 |
1988年 | 14篇 |
1987年 | 18篇 |
1986年 | 14篇 |
1985年 | 11篇 |
1984年 | 21篇 |
1983年 | 9篇 |
1982年 | 14篇 |
1979年 | 11篇 |
1978年 | 12篇 |
1977年 | 14篇 |
1976年 | 11篇 |
1975年 | 15篇 |
1974年 | 11篇 |
1973年 | 17篇 |
1972年 | 17篇 |
1971年 | 28篇 |
1970年 | 16篇 |
1969年 | 19篇 |
1968年 | 14篇 |
1966年 | 12篇 |
排序方式: 共有1352条查询结果,搜索用时 140 毫秒
1.
P Kaliman V Baron N Gautier E Van Obberghen 《The Journal of biological chemistry》1992,267(15):10645-10651
To approach the question of why insulin-like growth factor-I (IGF-I) and insulin have different physiological actions, we developed antibodies directed against cytoplasmic regions of the IGF-I receptor exhibiting a low degree of homology with the corresponding sequences of the insulin receptor. We found that an antipeptide antibody directed against the beta-subunit carboxyl-terminal sequence (1232-1246) of the IGF-I receptor significantly reduced the in vitro receptor autophosphorylation. The ability of the synthetic peptide corresponding to the IGF-I receptor sequence 1232-1246 to abolish this inhibitory effect reflects the specific nature of the antibody interaction with the targeted domain in the receptor. Antipeptide antibody to IGF-I receptor sequence 1232-1246 also decreased receptor phosphorylation activity toward the exogenous substrate poly(Glu/Tyr). The reduction in poly(Glu/Tyr) phosphorylation was seen even when the antibody was incubated with a receptor previously activated and phosphorylated. Therefore, the inhibitory action on substrate phosphorylation is likely to be unrelated to the antibody reduction of receptor autophosphorylation but rather results from a global decrease in receptor enzymatic activity. The effect of the antipeptide antibody on receptor tyrosine kinase cannot be accounted for by a lowering of the receptor Km for ATP or of its affinity for the substrate poly(Glu/Tyr). Moreover, the interaction of the antibody with the receptor had no repercussion on the ligand binding site as shown by the unaltered IGF-I binding. Taken together our data suggest that the beta-subunit carboxyl-terminal domain of the IGF-I receptor plays a key role in regulating its kinase activity and that the particular sequence recognized by our antipeptide antibody could be involved in negative regulation of receptor functioning. 相似文献
2.
3.
4.
Frank J. Baron 《American journal of botany》1978,65(7):804-810
The typical, irregular, delayed germination of sugar pine seeds was studied under different conditions of environment and seed dissection. Individual seeds showed a 3-phase pattern of water uptake which was obscured when average values for groups of seeds were used. Stratification at 5 C slowed the rate of imbibition as well as the growth rate, but when followed after 3 months by return to 20 C, germination was uniformly rapid. Complete removal of the seed coats yielded prompt germination without stratification. The thin layer of the inner coat was a critical factor. Slitting this layer indicated less significance for gas exchange or mechanical restraint than for a restriction upon the rate of water uptake. Regardless of the method of seed treatment, the visible stages of germination consistently occurred within well-defined levels of water uptake. The delicate balance between water entry and use as well as the internal distribution of water within seed components should be evaluated, rather than a mere expression of the total amount of water in a seed. 相似文献
5.
An antibody produced against epoxide hydratase (EC 4.2.1.63) which had been purified to apparent homogeneity from hepatic microsomes of phenobarbital pretreated rats was employed in an unlabeled antibody peroxidase-antiperoxidase technique to localize the enzyme at the light microscopic level in the livers of untreated rats. Immunohistochemical staining for epoxide hydratase was detected in parenchymal cells throughout the liver lobule. Cells within the centrilobular regions, however, were observed to be stained more intensely than were those within the midzonal and periportal regions of the lobule. The results of this immunohistochemical study thus demonstrate that epoxide hydratase does not exhibit a uniform pattern of distribution within the liver lobule in untreated rats. 相似文献
6.
Arts medicine has come of age, resulting from 3 important developments over the past decade: improved methods of diagnosis and treatment, an awareness that artists suffer from special problems related to their occupation and lifestyle, and the establishment of health programs emphasizing an interdisciplinary approach to these patients. We focus on the patterns of illness afflicting performing artists, specifically dancers, singers, actors, and instrumental musicians, and explain some of the things a health care team can do in treating these patients. The conditions governing these patients'' lives--early exposure to high expectations of excellence, incessant demands for perfection, long periods of intense practicing, fierce competition, high levels of anxiety associated with performance, and uncertain careers--need to be understood. Levels of disease and disability are remarkably high, but artists often ignore symptoms. We discuss the musculoskeletal, neurologic, vocal, psychological, and other syndromes found among performers and some of the difficulties in treating them. The prevention of injury, conservative management, collaboration with teachers, and a psychotherapeutic approach are desirable. Arts medicine programs for professional consultation exist in several major cities of the United States and abroad. Although research is needed regarding the effectiveness of health care services for performing artists, the scientific literature devoted to this field is growing. 相似文献
7.
J H Baron 《BMJ (Clinical research ed.)》1984,289(6448):807-810
8.
9.
10.