全文获取类型
收费全文 | 2863篇 |
免费 | 190篇 |
出版年
2023年 | 10篇 |
2021年 | 26篇 |
2020年 | 27篇 |
2019年 | 25篇 |
2018年 | 36篇 |
2017年 | 40篇 |
2016年 | 50篇 |
2015年 | 78篇 |
2014年 | 105篇 |
2013年 | 137篇 |
2012年 | 162篇 |
2011年 | 160篇 |
2010年 | 115篇 |
2009年 | 116篇 |
2008年 | 153篇 |
2007年 | 135篇 |
2006年 | 134篇 |
2005年 | 135篇 |
2004年 | 159篇 |
2003年 | 157篇 |
2002年 | 116篇 |
2001年 | 92篇 |
2000年 | 71篇 |
1999年 | 63篇 |
1998年 | 53篇 |
1997年 | 36篇 |
1996年 | 38篇 |
1995年 | 33篇 |
1994年 | 34篇 |
1993年 | 50篇 |
1992年 | 47篇 |
1991年 | 46篇 |
1990年 | 42篇 |
1989年 | 35篇 |
1988年 | 22篇 |
1987年 | 33篇 |
1986年 | 34篇 |
1985年 | 23篇 |
1984年 | 17篇 |
1983年 | 19篇 |
1982年 | 17篇 |
1981年 | 19篇 |
1980年 | 12篇 |
1979年 | 20篇 |
1978年 | 12篇 |
1977年 | 16篇 |
1975年 | 11篇 |
1974年 | 13篇 |
1973年 | 14篇 |
1972年 | 12篇 |
排序方式: 共有3053条查询结果,搜索用时 781 毫秒
91.
92.
Karin Dahlgren Caldwell Rolf Axn Margareta Bergwall Ingmar Olsson Jerker Porath 《Biotechnology and bioengineering》1976,18(11):1605-1614
Hexyl-groups have been introduced into crosslinked Sepharose 6B, yielding gels with degrees of substitution which range from 0.02 to 0.70 mol hexyl-side chain per mole galactose residue. The gels were exposed to β-amylase in solution, and the resulting adsorbates indicated a monotonic increase in adsorption capacity with an increasing hexyl-content. Adsorbate activity, by contrast, displayed a maximum for a carrier gel with a hexyl–galactose ratio of 0.51. Adsorbates based on gels with different hexyl-content were used in column reactors for continuous maltose production from a soluble starch substrate. 相似文献
93.
94.
Mats Thulin 《Nordic Journal of Botany》1999,19(2):199-208
Pavonia friisii , sp. nov., from south-eastern Ethiopia and south-central and southern Somalia, P. nigrescens , sp. nov., from south-central and southern Somalia, P. matteiana , sp. nov., from south-central Somalia, P. longipilosa , sp. nov., from eastern Ethiopia, P. rotundifolia , sp. nov., from eastern Ethiopia and northern and central Somalia, P. marginata , sp. nov., from central Somalia, and P. paucibracteata , sp. nov., from central Somalia, are described and illustrated. 相似文献
95.
The rapidly growing body of sequenced DNA demands efficientcomputer programs for its analysis and storage. The programdescribed in this paper, SEQ-ED, has been designed to handlea large number of DNA sequences up to 200 kilobases [kb] longstored in a sequence library. In order to minimize the requiredstorage space, the sequences are stored in a compressed formatusing three binary digits per base. In the development of thisprogram, special care has been given to make it easy to usefor molecular biologists without any previous computer experience.
Received on September 10, 1984; accepted on October 30, 1984 相似文献
96.
97.
98.
99.
Luise Ehlers Karen Bannert Sarah Rohde Peggy Berlin Johannes Reiner Mats Wiese Julia Doller Markus M. Lerch Ali A. Aghdassi Fatuma Meyer Luzia Valentini Ottavia Agrifoglio Cornelia C. Metges Georg Lamprecht Robert Jaster 《Journal of cellular and molecular medicine》2020,24(15):8304-8314
Muscle wasting represents a constant pathological feature of common chronic gastrointestinal diseases, including liver cirrhosis (LC), inflammatory bowel diseases (IBD), chronic pancreatitis (CP) and pancreatic cancer (PC), and is associated with increased morbidity and mortality. Recent clinical and experimental studies point to the existence of a gut‐skeletal muscle axis that is constituted by specific gut‐derived mediators which activate pro‐ and anti‐sarcopenic signalling pathways in skeletal muscle cells. A pathophysiological link between both organs is also provided by low‐grade systemic inflammation. Animal models of LC, IBD, CP and PC represent an important resource for mechanistic and preclinical studies on disease‐associated muscle wasting. They are also required to test and validate specific anti‐sarcopenic therapies prior to clinical application. In this article, we review frequently used rodent models of muscle wasting in the context of chronic gastrointestinal diseases, survey their specific advantages and limitations and discuss possibilities for further research activities in the field. We conclude that animal models of LC‐, IBD‐ and PC‐associated sarcopenia are an essential supplement to clinical studies because they may provide additional mechanistic insights and help to identify molecular targets for therapeutic interventions in humans. 相似文献
100.
Katharina Meurer Jennie Barron Claire Chenu Elsa Coucheney Matthew Fielding Paul Hallett Anke M. Herrmann Thomas Keller John Koestel Mats Larsbo Elisabet Lewan Dani Or David Parsons Nargish Parvin Astrid Taylor Harry Vereecken Nicholas Jarvis 《Global Change Biology》2020,26(10):5382-5403
Soil degradation is a worsening global phenomenon driven by socio‐economic pressures, poor land management practices and climate change. A deterioration of soil structure at timescales ranging from seconds to centuries is implicated in most forms of soil degradation including the depletion of nutrients and organic matter, erosion and compaction. New soil–crop models that could account for soil structure dynamics at decadal to centennial timescales would provide insights into the relative importance of the various underlying physical (e.g. tillage, traffic compaction, swell/shrink and freeze/thaw) and biological (e.g. plant root growth, soil microbial and faunal activity) mechanisms, their impacts on soil hydrological processes and plant growth, as well as the relevant timescales of soil degradation and recovery. However, the development of such a model remains a challenge due to the enormous complexity of the interactions in the soil–plant system. In this paper, we focus on the impacts of biological processes on soil structure dynamics, especially the growth of plant roots and the activity of soil fauna and microorganisms. We first define what we mean by soil structure and then review current understanding of how these biological agents impact soil structure. We then develop a new framework for modelling soil structure dynamics, which is designed to be compatible with soil–crop models that operate at the soil profile scale and for long temporal scales (i.e. decades, centuries). We illustrate the modelling concept with a case study on the role of root growth and earthworm bioturbation in restoring the structure of a severely compacted soil. 相似文献