全文获取类型
收费全文 | 156篇 |
免费 | 8篇 |
国内免费 | 43篇 |
专业分类
207篇 |
出版年
2024年 | 3篇 |
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 8篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2017年 | 5篇 |
2016年 | 8篇 |
2015年 | 6篇 |
2014年 | 13篇 |
2013年 | 9篇 |
2012年 | 9篇 |
2011年 | 15篇 |
2010年 | 10篇 |
2009年 | 14篇 |
2008年 | 11篇 |
2007年 | 10篇 |
2006年 | 10篇 |
2005年 | 8篇 |
2004年 | 7篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有207条查询结果,搜索用时 0 毫秒
201.
202.
203.
NA LUO FANGMING XIAO JAMES J. CAMBERATO YIWEI JIANG 《Plant, cell & environment》2013,36(11):2021-2033
Natural variation in salinity response, effects of population structure on growth and physiological traits and gene–trait association were examined in 56 global collections of diverse perennial ryegrass (Lolium perenne L.) accessions. Three population structure groups were identified with 66 simple sequence repeat markers, which on average accounted for 9 and 11% of phenotypic variation for the control and salinity treatment at 300 mm NaCl. Group 1 (10 accessions) had greater plant height, leaf dry weight and water content, chlorophyll index, K+ concentration and K+/Na+ than group 2 (39 accessions) and group 3 (7 accessions) under salinity stress, while group 3 had higher Na+ than groups 1 and 2. Eighty‐seven single nucleotide polymorphisms were detected from four partial candidate genes encoding aquaporin and Na+/H+ antiporter in both plasma and tonoplast membranes. Overall, rapid decay of linkage disequilibrium was observed within 500 bp. Significant associations were found between the putative LpTIP1 and Na+ for the control and between the putative LpNHX1 and K+/Na+ under the control and salinity treatments after controlling population structure. These results indicate that population structure influenced phenotypic traits, and allelic variation in LpNHX1 may affect salinity tolerance of perennial ryegrass. 相似文献
204.
205.
In general, optimal reaction norms in heterogeneous populations can be obtained only by iterative numerical procedures (McNamara,
1991; Kawecki and Stearns, 1993). We consider two particular, but biologically plausible and analytically tractable cases
of individual optimization to gain insight into the mechanisms which shape the optimal reaction norm of fecundity in relation
to an environmental variable or an individual trait. In the first case, we assume that the quality of the environment (e.g.
food abundance) or the quality of the individual (e.g. body size) is fixed during its entire life; it may also be a heritable
individual trait. In the second case, individual quality is assumed to change randomly such that the probability distribution
of quality in the next year is the same for the parent and for her offspring. For these two cases, we obtain analytical expressions
for the shape of the optimal reaction norm, which are heuristically interpretable in terms of underlying selective mechanisms.
It is shown that better quality may reduce the optimal fecundity. This outcome is particularly likely if better quality increases
a fecundity-independent factor of parental survival in a long-lived species with fixed quality.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
206.
Diagnostic self‐testing devices are being developed for many illnesses, chronic diseases and infections. These will be used in hospitals, at point‐of‐care facilities and at home. Designed to allow earlier detection of diseases, self‐testing diagnostic devices may improve disease prevention, slow the progression of disease and facilitate better treatment outcomes. These devices have the potential to benefit both the individual and society by enabling individuals to take a more proactive role in the maintenance of their health and by helping society improve health and reduce health costs. However, the full implications of future home‐based diagnostic technology for individuals and society remain unclear due to their novelty. We argue that the development of diagnostic tools, especially for home use, will heighten a number of ethical challenges. This paper will explore some of the ethical implications of home‐based self‐testing diagnostic devices for the autonomous and relational dimensions of the person. This will be facilitated by examining the impact of diagnostic devices for individual autonomy, for the delivery of accurate diagnosis and for the personal significance of the information for the user. The latter will be examined using Charles Taylor's view of personhood and his emphasis on human agency and interpretation. While the ethical issues are not necessarily new, the development of home‐based self‐testing diagnostic devices will make issues regarding autonomy, accuracy of information and personal significance more and more demanding. This will be the case particularly when an individual's autonomous choices come into conflict with the person's relational responsibilities. 相似文献
207.
奥陶纪是串管海绵早期演化的一个关键阶段,记录了该类群的首次大规模辐射演化事件(属级分类单元达15个)。然而,现有大部分奥陶系串管海绵的报道来自澳大利亚东部和北美等地,在中国至今仅发现了两个属,与前述地区相比研究程度偏低。早期研究主要基于形态学特征对串管海绵进行系统分类描述,对其滤食策略知之甚少,因此制约了对此类海绵在奥陶纪底栖生态系统作用的相关探讨。本文系新疆塔里木柯坪地区奥陶纪串管海绵的首次系统古生物学报道,详细描述凯迪阶(上奥陶统)印干组中保存完好的阔室丛花海绵(Corymbospongia amplia)化石的形态学特征,并通过研究标本外壁微孔孔径的大小分布,探讨其滤食选择性。海绵外壁微孔孔径的分析表明:小型和微型浮游生物可能是其食物的主要来源,而多细胞浮游动物因个体尺寸大于海绵外壁微孔,不能被阔室丛花海绵捕获。本研究为奥陶纪串管海绵古生态学及其地球生物学意义的探讨提供了进一步的依据。 相似文献