全文获取类型
收费全文 | 6792篇 |
免费 | 620篇 |
国内免费 | 68篇 |
出版年
2023年 | 50篇 |
2022年 | 47篇 |
2021年 | 194篇 |
2020年 | 129篇 |
2019年 | 180篇 |
2018年 | 190篇 |
2017年 | 201篇 |
2016年 | 241篇 |
2015年 | 414篇 |
2014年 | 402篇 |
2013年 | 521篇 |
2012年 | 607篇 |
2011年 | 554篇 |
2010年 | 399篇 |
2009年 | 350篇 |
2008年 | 419篇 |
2007年 | 360篇 |
2006年 | 325篇 |
2005年 | 278篇 |
2004年 | 299篇 |
2003年 | 217篇 |
2002年 | 225篇 |
2001年 | 69篇 |
2000年 | 44篇 |
1999年 | 51篇 |
1998年 | 48篇 |
1997年 | 45篇 |
1996年 | 36篇 |
1995年 | 37篇 |
1994年 | 34篇 |
1993年 | 40篇 |
1992年 | 30篇 |
1991年 | 29篇 |
1990年 | 36篇 |
1989年 | 32篇 |
1988年 | 19篇 |
1987年 | 20篇 |
1986年 | 18篇 |
1985年 | 26篇 |
1984年 | 29篇 |
1983年 | 18篇 |
1982年 | 25篇 |
1981年 | 16篇 |
1980年 | 16篇 |
1979年 | 15篇 |
1978年 | 12篇 |
1977年 | 11篇 |
1976年 | 11篇 |
1975年 | 12篇 |
1967年 | 7篇 |
排序方式: 共有7480条查询结果,搜索用时 453 毫秒
111.
Michael Meyer Maya Ben‐Yehuda Greenwald Theresa Rauschendorfer Catharina Snger Marko Jukic Haruka Iizuka Fumimasa Kubo Lin Chen David M. Ornitz Sabine Werner 《Journal of cellular and molecular medicine》2020,24(2):1774-1785
Fibroblast growth factors (FGFs) are key regulators of tissue development, homeostasis and repair, and abnormal FGF signalling is associated with various human diseases. In human and murine epidermis, FGF receptor 3 (FGFR3) activation causes benign skin tumours, but the consequences of FGFR3 deficiency in this tissue have not been determined. Here, we show that FGFR3 in keratinocytes is dispensable for mouse skin development, homeostasis and wound repair. However, the defect in the epidermal barrier and the resulting inflammatory skin disease that develops in mice lacking FGFR1 and FGFR2 in keratinocytes were further aggravated upon additional loss of FGFR3. This caused fibroblast activation and fibrosis in the FGFR1/FGFR2 double‐knockout mice and even more in mice lacking all three FGFRs, revealing functional redundancy of FGFR3 with FGFR1 and FGFR2 for maintaining the epidermal barrier. Taken together, our study demonstrates that FGFR1, FGFR2 and FGFR3 act together to maintain epidermal integrity and cutaneous homeostasis, with FGFR2 being the dominant receptor. 相似文献
112.
Schlacher Thomas A. Gilby Ben L. Olds Andrew D. Henderson Christopher J. Connolly Rod M. Peterson Charles H. Voss Christine M. Maslo Brooke Weston Michael A. Bishop Melanie J. Rowden Ashley 《Ecosystems》2020,23(4):906-916
Ecosystems - Ecotones can form hot spots of biodiversity by containing species from multiple ecosystems. Because biodiversity is often linked to ecological function, we posit that rates of key... 相似文献
113.
Hansen Joan H. Skov Christian Baktoft Henrik Brönmark Christer Chapman Ben B. Hulthén Kaj Hansson Lars-Anders Nilsson P. Anders Brodersen Jakob 《Ecosystems》2020,23(2):292-306
Ecosystems - Patterns of animal migration and the ecological forces that shape them have been studied for centuries. Yet ecological impacts caused by the migration, such as altered... 相似文献
114.
David B. Lindenmayer Peter Lane Martin J. Westgate Ben C. Scheele Mason Crane Daniel Florance Clare Crane David Smith 《Austral ecology》2020,45(6):813-824
Many studies have documented the individual effects of variables such as vegetation, long‐term climate and short‐term weather on biodiversity. Few, however, have explicitly explored how interactions among these major drivers can influence species abundance. We used data from a 15‐year study (2002–2017) in the endangered temperate woodlands of south‐eastern Australia to test hypotheses associated with the effects of vegetation type, long‐term climate and short‐term weather on population trajectories of seven species of (largely) nocturnal mammals and birds. Despite prolonged drought conditions, there was a significant increase in the abundance of some species over time (e.g. the Eastern Grey Kangaroo). It is possible that destocking of domestic livestock may have reduced competition with Kangaroos, thereby facilitating increases in abundance. The Common Brushtail Possum and Common Ringtail Possum were significantly less likely to occur in replanted woodlands, possibly because of the paucity of nesting sites. We found no evidence that replanted woodlands are refuges for exotic pest species like the European Rabbit and Red Fox. Short‐ and long‐term rainfall and vegetation type had important independent and combined effects on animal abundance. That is, responses to periods of high short‐term rainfall were dependent on vegetation type and whether sites occurred in long‐term climatically wet versus climatically dry locations. For example, the Red Fox responded positively to high levels of short‐term rainfall, but only at climatically dry sites. Our results highlight the complementary value of different vegetation types across the landscape and the context‐specific responses of animals to short‐term fluctuations in moisture availability. They also underscore the value of long‐term monitoring at a landscape scale for examining how multiple interacting factors influence trends in animal abundance. 相似文献
115.
116.
The hypothesis that environmental heterogeneity promotes species richness by increasing opportunities for niche partitioning is a fundamental paradigm in ecology. However, recent studies suggest that heterogeneity–diversity relationships (HDR) are more complex than expected from this niche‐based perspective, and often show a decrease in richness at high levels of heterogeneity. These findings have motivated ecologists to propose new mechanisms that may explain such deviations. Here we provide an overview of currently recognised mechanisms affecting the shape of HDRs and present a conceptual model that integrates all previously proposed mechanisms within a unified framework. We also translate the proposed framework into an explicit community dynamic model and use the model as a tool for generating testable predictions concerning how landscape properties interact with species traits in determining the shape of HDRs. Our main finding is that, despite the enormous complexity of such interactions, the predicted HDRs are rather simple, ranging from positive to unimodal patterns in a highly consistent and predictable manner. 相似文献
117.
Koffler Christoph Amor Ben Carbajales-Dale Michael Cascio Joseph Conroy Alison Fava James A. Gaudreault Caroline Gloria Thomas Hensler Connie Horvath Arpad Humbert Sebastien Manzardo Alessandro Margni Manuele Osset Philippe Sinistore Julie Vigon Bruce Wallace Michele L Wang Michael Prox Martina 《The International Journal of Life Cycle Assessment》2020,25(3):478-482
The International Journal of Life Cycle Assessment - 相似文献
118.
大熊猫是生态保护的旗舰物种,保护大熊猫及其栖息地具有重要的示范作用和科学价值。中国致力于建设以国家公园为主体的自然保护地体系,分析大熊猫保护地生态安全,为建立大熊猫国家公园提供理论依据,具有重要意义。以四川省为例,选取被划入或将来可能被划入大熊猫保护地的典型县域,构建大熊猫保护地生态安全评价指标体系,采用熵权法、层次分析法进行综合评价,并结合空间相关性分析,从时间和空间两个维度对大熊猫保护地生态安全状况进行时空动态分析。结果表明:(1)2003-2017年四川省大熊猫保护地生态安全综合指数呈波动性上升趋势,生态环境改善显著,但仍有部分县域出现不同程度的环境恶化现象。(2)各县域生态安全状况表现出较强的差异性,并且相邻县域生态安全指数存在显著的空间正相关性和空间集聚性。(3)大熊猫保护地生态安全与周边社会经济发展之间矛盾依然尖锐,相邻县域之间的经济发展和生态保护状况相互影响的作用明显,需联合治理,共同促进生态平衡,提高大熊猫及其栖息地保护效果。 相似文献
119.
120.
Hansford Kayleigh M. McGinley Liz Wilkinson Samantha Gillingham Emma L. Cull Ben Gandy Sara Carter Daniel P. Vaux Alexander G. C. Richards Simon Hayes Alister Medlock Jolyon M. 《Experimental & applied acarology》2021,84(3):593-606
Experimental and Applied Acarology - Assessing the risk of tick-borne disease in areas with high visitor numbers is important from a public health perspective. Evidence suggests that tick presence,... 相似文献