全文获取类型
收费全文 | 498篇 |
免费 | 42篇 |
出版年
2018年 | 6篇 |
2016年 | 11篇 |
2015年 | 7篇 |
2014年 | 12篇 |
2013年 | 10篇 |
2012年 | 12篇 |
2011年 | 20篇 |
2010年 | 12篇 |
2009年 | 10篇 |
2008年 | 12篇 |
2007年 | 17篇 |
2006年 | 22篇 |
2005年 | 23篇 |
2004年 | 12篇 |
2003年 | 25篇 |
2002年 | 10篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 11篇 |
1998年 | 10篇 |
1997年 | 9篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1994年 | 7篇 |
1993年 | 8篇 |
1992年 | 6篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 12篇 |
1988年 | 10篇 |
1987年 | 14篇 |
1986年 | 10篇 |
1985年 | 10篇 |
1984年 | 8篇 |
1983年 | 7篇 |
1982年 | 11篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1978年 | 10篇 |
1976年 | 8篇 |
1975年 | 5篇 |
1974年 | 7篇 |
1973年 | 10篇 |
1972年 | 8篇 |
1971年 | 8篇 |
1968年 | 4篇 |
1967年 | 5篇 |
1966年 | 4篇 |
1965年 | 4篇 |
排序方式: 共有540条查询结果,搜索用时 15 毫秒
491.
492.
493.
Feng-Hou Huang Franklin C. Cech Roy B. Clarkson 《Biochemical Systematics and Ecology》1975,3(3):143-147
Investigations of soluble proteins by polyacrylamide gel electrophoresis of root extracts of black locust (Robinia pseudoacacia L.) were carried out with 41 trees from diverse habitats representing dominant-stem forms (R. p. var. rectissima Raber) and typical forms (R. pseudoacacia L.). Soluble protein patterns of dominantstem forms and typical trees did not show differences attributable to tree form. Heritability estimates (broad sense) were determined as 9·19% within location and 7·.5% among populations. A variance components model was constructed which showed the interaction between parental trees and location to be most significant in determining variation. Location variance was second in importance, with parental variance and experimental error of less significance. The data were analyzed by the moment of inertia. It is indicated that, based on protein similarity, the dominant-stem form is an ecological variant and should not be given varietal status. 相似文献
494.
495.
Both the J5 and BA-3 monoclonal antibodies are considered to be specific for epitopes on the common acute lymphoblastic leukemia antigen (CALLA). Flow-cytometric analyses of three cell lines and one normal bone marrow sample using these antibodies as CALLA markers demonstrated that J5-labeled cells were always brighter than those labeled with BA-3, and that the ratio of their fluorescence intensities varied widely in the different systems. Furthermore, one of the lines, RPMI 8226, while positive for J5, appeared to be negative when labeled with BA-3, except for a slight displacement of the fluorescence distribution relative to the control. A possible explanation for the observed results is that the BA-3 binding epitope or epitopes on CALLA may vary in their number and/or accessibility to the antibody. These observations suggest that the use of a single monoclonal antibody to detect a cell surface antigen may be misleading, particularly when a negative result is obtained. 相似文献
496.
Blandine Laferrère M.D. ShanKuan Zhu Jennifer R. Clarkson Marianne R.M. Yoshioka Katherine Krauskopf John C. Thornton F. Xavier Pi-Sunyer 《Obesity (Silver Spring, Md.)》2002,10(12):1270-1275
Objective: To investigate the health-related quality of life (HR-QOL) in African-American (AA) and white (W) obese women. Research Methods and Procedures: Participants were 145 obese women (80 AA and 65 W; 87 premenopausal and 58 postmenopausal) who completed the Medical Outcomes Study short form, the Brief Symptom Inventory, the Life Distress Inventory, the Satisfaction With Life Scale, and the Rosenberg Self-Esteem Scale before entering a weight-loss study. The mean age of the subjects was 46.3 ± 11.1 years and the mean body mass index was 35.2 ± 4.2 kg/m2. Results: Although AA women were slightly heavier (95.3 ± 10.3 kg vs. 91.5 ± 11.6 kg, p < 0.05) and less educated (14.2 ± 3.7 years vs. 15.7 ± 3.7 years, p < 0.05) than the W women in the sample, there was no difference between the two ethnic groups in any of the reported HR-QOL variables. Menopausal status had a significant effect on HR-QOL, with premenopausal women being more distressed (p = 0.002), having more limitations in social activity (p = 0.007), and having less vitality (p < 0.001) than the postmenopausal women. This was especially true in the AA women. Discussion: These data show no difference in HR-QOL between AA and W obese women and suggest that menopausal status may have an impact on HR-QOL, especially in AA women. 相似文献
497.
Partner P.L.R.; Smith M.L.; Spoor W.; Clarkson M.I. 《Bioinformatics (Oxford, England)》1993,9(5):597-605
A computer simulation model demonstrating the effect of directionalselection upon a simplified quantitative genetic character,is presented. Complementary homozygous parents were crossedto generate a filly heterozygous F1 population. Phenolypic truncationselection was effected upon the F2 and subsequent generations,and genotypic and phenolypic response to selection, as wellas the change in population heterozygosizy, was monitored togeneration F9 The model simulates selection for alternativebreeding regimes, modes of allelic interaction, selection pressure,population size and levels of environmental variation. Threealternative methods for the simulation of the environmentalcomponent of phenozypic variance are incorporated, and mechanismsand relative merits of the rival methods are discussed. Datagenerated by the model confonned closely to theoretical expectation,lending support to the use of the model as a platform for developmentof more comprehensive simulation models. Potential improvementsto the model are discussed. 相似文献
498.
Summary Incidence in the field of crop disorders known to be due to localised calcium deficiency bears little relation to soil calcium
status, and is more often associated with particular types of weather. We are suggesting that brief periods of soil partial
anaerobiosis following wet weather, and other unfavourable soil physical conditions such as compaction, lead to a temporary
reduction in the distal, undifferentiated region of roots from which the majority of the calcium taken up is transported to
the shoot. This might lead to a transient calcium deficiency in rapidly growing shoot tissues, and thence to necrosis. 相似文献
499.
500.