全文获取类型
收费全文 | 281篇 |
免费 | 33篇 |
国内免费 | 32篇 |
专业分类
346篇 |
出版年
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 6篇 |
2019年 | 4篇 |
2018年 | 9篇 |
2017年 | 6篇 |
2016年 | 8篇 |
2015年 | 6篇 |
2014年 | 9篇 |
2013年 | 12篇 |
2012年 | 16篇 |
2011年 | 21篇 |
2010年 | 17篇 |
2009年 | 17篇 |
2008年 | 12篇 |
2007年 | 9篇 |
2006年 | 21篇 |
2005年 | 11篇 |
2004年 | 8篇 |
2003年 | 7篇 |
2002年 | 7篇 |
2001年 | 8篇 |
2000年 | 3篇 |
1999年 | 6篇 |
1998年 | 13篇 |
1997年 | 9篇 |
1996年 | 6篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1992年 | 7篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1971年 | 2篇 |
1963年 | 2篇 |
1959年 | 2篇 |
1958年 | 3篇 |
1957年 | 2篇 |
1955年 | 3篇 |
1953年 | 1篇 |
1952年 | 1篇 |
1949年 | 5篇 |
1948年 | 2篇 |
排序方式: 共有346条查询结果,搜索用时 15 毫秒
101.
102.
Indoor and outdoor winter activity of Culicoides biting midges,vectors of bluetongue virus,in Italy 下载免费PDF全文
A. MAGLIANO P. SCARAMOZZINO S. RAVAGNAN F. MONTARSI G. DA ROLD G. CINCINELLI A. MONI P. SILVESTRI A. CARVELLI C. DE LIBERATO 《Medical and veterinary entomology》2018,32(1):70-77
Indoor and outdoor winter activity of Culicoides spp. (Diptera: Ceratopogonidae) in central Italy was investigated in order to evaluate whether indoor activity might account for the overwintering of bluetongue virus, as has been hypothesized by some authors. Weekly Culicoides collections were performed at three farms over three consecutive winter seasons. At each farm, two black‐light traps were operated simultaneously, indoors and outdoors. Culicoides were identified using both morphological and molecular means. The Culicoides obsoletus group accounted for 98.2% of sampled specimens. Within this group, C. obsoletus s.s. accounted for 56.8% and Culicoides scoticus for 43.2% of samples. Nulliparous, parous and engorged females were caught throughout the entire winter, both indoors and outdoors. At times, indoor catch sizes outnumbered outdoor collections. A significant inverse correlation was found between minimum temperature and the proportion of indoor Culicoides of the total midge catch, thus indicating that lower outdoor temperatures drive Culicoides midges indoors. High rates of engorged females were recorded indoors, possibly as the result of the propensity of C. obsoletus females to feed indoors. Higher proportions of parous females were found in indoor than in outdoor catches, indicating higher survival rates indoors and, consequently, higher vectorial capacities of midges sheltering indoors compared with those remaining outdoors. 相似文献
103.
104.
Current information on the structure and function of motile tubular vacuoles in Pisolithus tinctorius and other fungi is reviewed. The use of fluorochromes to label the vacuole lumen is evaluated and observations on the structure and motility of vacuoles in P. tinctorius are differentiated from possible artifacts. The styryl dyes FM4-64 and MDY-64, used in yeast to demonstrate endocytosis, show little or no labeling of internal membranes in undamaged P. tinctorius cells. This agrees with our data showing that other probes for endocytosis such as Lucifer yellow CH are not taken up by hyphal tip cells. Overall, the observations do not support endocytosis in hyphal tips. It has been suggested that tubular vacuole systems carry out longitudinal transport, and evidence in favor of this hypothesis is evaluated. New data are presented to show that many of the large vacuoles in subapical cells are attached to the plasma membrane and are relatively immobile, while video sequences show movement of fluorochrome in pulses along a series of several large vacuoles, all interconnected via tubules. Tubular vacuoles from thick sections of hyphae processed under anhydrous conditions are shown by X-ray microanalysis to contain relatively high levels of P and K, as seen previously in the larger vacuoles. These results provide further evidence for a role of the tubular vacuoles in longitudinal transport of P. Copyright 1998 Academic Press. 相似文献
105.
106.
细胞外三磷酸腺苷(extracellular adenosine-5'-triphosphate)是植物细胞的重要信号分子。以烟草悬浮细胞BY-2(Nicotiana tabacum L.cv.Bright Yellow-2)为材料,探讨了胞外三磷酸腺苷对铅胁迫下细胞损伤、H2O2(过氧化氢)含量及H2O2清除酶活性的影响。结果显示,随着Pb(NO3)2浓度的不断提高(30~400 μmol·L-1),细胞外三磷酸腺苷含量呈现出逐渐下降的趋势,但胞内三磷酸腺苷含量及细胞的受损伤程度逐渐增大;同时,H2O2含量和过氧化氢酶的活性均有所上升,并在200 μmol·L-1 Pb(NO3)2处理下达到最大值,而过氧化物酶的活性则不断降低。较之Pb(NO3)2胁迫下的细胞,对Pb(NO3)2胁迫的细胞加入外源三磷酸腺苷使得细胞受损伤程度显著降低,H2O2含量减少,过氧化氢酶活性减弱,而过氧化物酶活性增强。实验结果表明,Pb(NO3)2胁迫诱导的植物细胞损伤和H2O2及其清除酶水平的变化能受到细胞外三磷酸腺苷水平的调节。 相似文献
107.
108.
109.
110.