全文获取类型
收费全文 | 763篇 |
免费 | 57篇 |
出版年
2013年 | 12篇 |
2012年 | 14篇 |
2011年 | 14篇 |
2010年 | 22篇 |
2009年 | 22篇 |
2008年 | 17篇 |
2007年 | 21篇 |
2006年 | 16篇 |
2005年 | 13篇 |
2004年 | 9篇 |
2003年 | 7篇 |
2002年 | 7篇 |
2000年 | 7篇 |
1998年 | 8篇 |
1997年 | 17篇 |
1995年 | 12篇 |
1994年 | 6篇 |
1993年 | 14篇 |
1992年 | 13篇 |
1991年 | 12篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 12篇 |
1985年 | 10篇 |
1983年 | 9篇 |
1982年 | 12篇 |
1981年 | 9篇 |
1980年 | 7篇 |
1979年 | 7篇 |
1978年 | 11篇 |
1977年 | 8篇 |
1976年 | 13篇 |
1975年 | 8篇 |
1974年 | 6篇 |
1972年 | 9篇 |
1971年 | 8篇 |
1959年 | 19篇 |
1958年 | 41篇 |
1957年 | 40篇 |
1956年 | 36篇 |
1955年 | 38篇 |
1954年 | 28篇 |
1953年 | 27篇 |
1952年 | 23篇 |
1951年 | 29篇 |
1950年 | 22篇 |
1949年 | 20篇 |
1948年 | 16篇 |
1946年 | 6篇 |
排序方式: 共有820条查询结果,搜索用时 15 毫秒
771.
772.
Does gall diameter affect the parasitism rate of Asphondylia borrichiae (Diptera: Cecidomyiidae)? 总被引:1,自引:0,他引:1
ANTHONY M. ROSSI PETER D. STILING DONALD R. STRONG† DEREK M. JOHNSON 《Ecological Entomology》1992,17(2):149-154
Abstract. 1. Fertilized field plots of Borrichia frutescens (L.) de Candolle produced plants with a higher apical-leaf nitrogen content than control plots.
2. Gall frequency of the cecidomyiid Asphondylia borrichiae Rossi & Strong on stems of B.frutescens , increased significantly on fertilized plots after approximately 3 months.
3. Fertilizer treatment did not result in changes in stem density but did tend to increase proportion of stems flowering and overall plant size. Galls are not normally found on flowering stems.
4. Galls grew at a faster rate and to a larger final size on fertilized plots.
5. On three sampling dates, per cent parasitism of galls was the same on fertilized and control plots; therefore, this study does not support the galldiameter hypothesis. 相似文献
2. Gall frequency of the cecidomyiid Asphondylia borrichiae Rossi & Strong on stems of B.frutescens , increased significantly on fertilized plots after approximately 3 months.
3. Fertilizer treatment did not result in changes in stem density but did tend to increase proportion of stems flowering and overall plant size. Galls are not normally found on flowering stems.
4. Galls grew at a faster rate and to a larger final size on fertilized plots.
5. On three sampling dates, per cent parasitism of galls was the same on fertilized and control plots; therefore, this study does not support the galldiameter hypothesis. 相似文献
773.
774.
Cervical screening is concerned with the search for abnormal epithelial cells in smears prepared from scrapings from the uterine cervix. It is a highly skilled labour intensive operation and automated methods of detecting dyskariotic cells in cervical smears would be helpful. We report a fluorescence method of detecting abnormal cervical cells in smears and biopsies using a probe for guanidinobenzoatase. This approach has the potential for automation. 相似文献
775.
CHAD R. RUND JAMES L. CHRISTIANSEN JAMES C. JOHNSON 《Pigment cell & melanoma research》1998,11(2):114-119
Melanomacrophages were extracted and cultured from the spleen and liver of three turtle species representing three divergent families, the Chelydridae, Emydidae, and Trionychidae. Homogeneous cultures were obtained by repeatedly forcing minced, frequently washed tissue through a sterile screen and separating the resulting cells by centrifugation. The cells were surprisingly resistant to lysis and were maintained in culture for over 12 weeks where culture characteristics, appearance, and longevity from these two organs were similar. They attached to the T flask substrate as individual cells and aggregates and spread out 14 days after being placed in media. Ridges and ruffles at the distal ends of pseudopodia and the cell surface along with a zone of clearing attest to the cells’phagocytic nature. A few melanomacrophages from both organs underwent mitosis 14 days after treatment with granulocyte macrophage colony-stimulating factor but it is possible that other factors contributed to stimulation of cell division. 相似文献
776.
777.
778.
779.
780.