全文获取类型
收费全文 | 309篇 |
免费 | 26篇 |
出版年
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 8篇 |
2015年 | 10篇 |
2014年 | 12篇 |
2013年 | 17篇 |
2012年 | 20篇 |
2011年 | 14篇 |
2010年 | 13篇 |
2009年 | 21篇 |
2008年 | 15篇 |
2007年 | 14篇 |
2006年 | 15篇 |
2005年 | 16篇 |
2004年 | 7篇 |
2003年 | 12篇 |
2002年 | 10篇 |
2001年 | 12篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 8篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1994年 | 3篇 |
1989年 | 6篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1983年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1972年 | 2篇 |
1970年 | 2篇 |
1968年 | 3篇 |
1967年 | 2篇 |
1964年 | 2篇 |
1960年 | 2篇 |
1955年 | 3篇 |
1951年 | 3篇 |
1944年 | 1篇 |
1943年 | 1篇 |
1917年 | 1篇 |
1904年 | 1篇 |
排序方式: 共有335条查询结果,搜索用时 78 毫秒
161.
162.
Evaluating citizen science data for forecasting species responses to national forest management
下载免费PDF全文
![点击此处可从《Ecology and evolution》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Louise Mair Philip J. Harrison Mari Jönsson Swantje Löbel Jenni Nordén Juha Siitonen Tomas Lämås Anders Lundström Tord Snäll 《Ecology and evolution》2017,7(1):368-378
The extensive spatial and temporal coverage of many citizen science datasets (CSD) makes them appealing for use in species distribution modeling and forecasting. However, a frequent limitation is the inability to validate results. Here, we aim to assess the reliability of CSD for forecasting species occurrence in response to national forest management projections (representing 160,366 km2) by comparison against forecasts from a model based on systematically collected colonization–extinction data. We fitted species distribution models using citizen science observations of an old‐forest indicator fungus Phellinus ferrugineofuscus. We applied five modeling approaches (generalized linear model, Poisson process model, Bayesian occupancy model, and two MaxEnt models). Models were used to forecast changes in occurrence in response to national forest management for 2020‐2110. Forecasts of species occurrence from models based on CSD were congruent with forecasts made using the colonization–extinction model based on systematically collected data, although different modeling methods indicated different levels of change. All models projected increased occurrence in set‐aside forest from 2020 to 2110: the projected increase varied between 125% and 195% among models based on CSD, in comparison with an increase of 129% according to the colonization–extinction model. All but one model based on CSD projected a decline in production forest, which varied between 11% and 49%, compared to a decline of 41% using the colonization–extinction model. All models thus highlighted the importance of protected old forest for P. ferrugineofuscus persistence. We conclude that models based on CSD can reproduce forecasts from models based on systematically collected colonization–extinction data and so lead to the same forest management conclusions. Our results show that the use of a suite of models allows CSD to be reliably applied to land management and conservation decision making, demonstrating that widely available CSD can be a valuable forecasting resource. 相似文献
163.
164.
Joel A Dave Nico C Gey van Pittius Albert D Beyers Mario RW Ehlers Gordon D Brown 《BMC microbiology》2002,2(1):30
Background
Exported proteases are commonly associated with virulence in bacterial pathogens, yet there is a paucity of information regarding their role in Mycobacterium tuberculosis. There are five genes (mycP1-5) present within the genome of Mycobacterium tuberculosis H37Rv that encode a family of secreted, subtilisin-like serine proteases (the mycosins). The gene mycP1 (encoding mycosin-1) was found to be situated 3700 bp (four ORF's) from the RD1 deletion region in the genome of the attenuated vaccine strain M. bovis BCG (bacille de Calmette et Guérin) and was selected for further analyses due to the absence of expression in this organism. 相似文献165.
Mechanism of high-mobility group protein B enhancement of progesterone receptor sequence-specific DNA binding 总被引:2,自引:1,他引:1
下载免费PDF全文
![点击此处可从《Nucleic acids research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The DNA-binding domain (DBD) of progesterone receptor (PR) is bipartite containing a zinc module core that interacts with progesterone response elements (PRE), and a short flexible carboxyl terminal extension (CTE) that interacts with the minor groove flanking the PRE. The chromosomal high-mobility group B proteins (HMGB), defined as DNA architectural proteins capable of bending DNA, also function as auxiliary factors that increase the DNA-binding affinity of PR and other steroid receptors by mechanisms that are not well defined. Here we show that the CTE of PR contains a specific binding site for HMGB that is required for stimulation of PR-PRE binding, whereas the DNA architectural properties of HMGB are dispensable. Specific PRE DNA inhibited HMGB binding to the CTE, indicating that DNA and HMGB–CTE interactions are mutually exclusive. Exogenous CTE peptide increased PR-binding affinity for PRE as did deletion of the CTE. In a PR-binding site selection assay, A/T sequences flanking the PRE were enriched by HMGB, indicating that PR DNA-binding specificity is also altered by HMGB. We conclude that a transient HMGB–CTE interaction alters a repressive conformation of the flexible CTE enabling it to bind to preferred sequences flanking the PRE. 相似文献
166.
167.
S. K. J. McConnell J. Leamon D. O. F. Skibinski G. C. Mair 《Molecular ecology resources》2001,1(3):115-116
The Indian major carp Catla catla is indigenous to the major river systems of Northern India, Pakistan and Bangladesh, and is an important contributor to aquaculture production in India and Bangladesh. Five polymorphic microsatellite loci, developed from Catla catla are described and their utility in other major carp and cyprinid species is tested. 相似文献
168.
169.
170.
During preimplantation development in mammals, distinct epigenetic marks on oocyte and sperm DNA are remodeled to an embryonic pattern. A recent study examining global methylation of repetitive elements in various mammals showed that the reprogramming that occurs during normal preimplantation development is aberrant in cloned embryos. 相似文献