全文获取类型
收费全文 | 815篇 |
免费 | 91篇 |
出版年
2021年 | 18篇 |
2020年 | 8篇 |
2018年 | 10篇 |
2016年 | 22篇 |
2015年 | 29篇 |
2014年 | 30篇 |
2013年 | 23篇 |
2012年 | 34篇 |
2011年 | 42篇 |
2010年 | 22篇 |
2009年 | 15篇 |
2008年 | 33篇 |
2007年 | 30篇 |
2006年 | 24篇 |
2005年 | 18篇 |
2004年 | 25篇 |
2003年 | 25篇 |
2002年 | 27篇 |
2001年 | 20篇 |
2000年 | 18篇 |
1999年 | 10篇 |
1998年 | 9篇 |
1997年 | 7篇 |
1996年 | 10篇 |
1995年 | 7篇 |
1994年 | 13篇 |
1993年 | 11篇 |
1992年 | 20篇 |
1991年 | 15篇 |
1990年 | 13篇 |
1989年 | 16篇 |
1988年 | 26篇 |
1987年 | 18篇 |
1986年 | 17篇 |
1985年 | 14篇 |
1984年 | 7篇 |
1983年 | 12篇 |
1982年 | 9篇 |
1981年 | 9篇 |
1979年 | 8篇 |
1978年 | 11篇 |
1977年 | 12篇 |
1976年 | 8篇 |
1975年 | 21篇 |
1974年 | 14篇 |
1972年 | 6篇 |
1971年 | 9篇 |
1970年 | 10篇 |
1969年 | 7篇 |
1965年 | 8篇 |
排序方式: 共有906条查询结果,搜索用时 15 毫秒
151.
Integrating correlation between traits improves spatial predictions of plant functional composition 下载免费PDF全文
Rafael O. Wüest Tamara Münkemüller Sébastien Lavergne Laura J. Pollock Wilfried Thuiller 《Oikos》2018,127(3):472-481
Functional trait composition is increasingly recognized as key to better understand and predict community responses to environmental gradients. Predictive approaches traditionally model the weighted mean trait values of communities (CWMs) as a function of environmental gradients. However, most approaches treat traits as independent regardless of known tradeoffs between them, which could lead to spurious predictions. To address this issue, we suggest jointly modeling a suit of functional traits along environmental gradients while accounting for relationships between traits. We use generalized additive mixed effect models to predict the functional composition of alpine grasslands in the Guisane Valley (France). We demonstrate that, compared to traditional approaches, joint trait models explain considerable amounts of variation in CWMs, yield less uncertainty in trait CWM predictions and provide more realistic spatial projections when extrapolating to novel environmental conditions. Modeling traits and their co‐variation jointly is an alternative and superior approach to predicting traits independently. Additionally, compared to a ‘predict first, assemble later’ approach that estimates trait CWMs post hoc based on stacked species distribution models, our ‘assemble first, predict later’ approach directly models trait‐responses along environmental gradients, and does not require data and models on species’ distributions, but only mean functional trait values per community plot. This highlights the great potential of joint trait modeling approaches in large‐scale mapping applications, such as spatial projections of the functional composition of vegetation and associated ecosystem services as a response to contemporary global change. 相似文献
152.
153.
154.
Kirti Richa Callie W. Babbitt Nenad G. Nenadic Gabrielle Gaustad 《The International Journal of Life Cycle Assessment》2017,22(1):66-81
Purpose
The purpose of this study was to analyze the environmental trade-offs of cascading reuse of electric vehicle (EV) lithium-ion batteries (LIBs) in stationary energy storage at automotive end-of-life.Methods
Two systems were jointly analyzed to address the consideration of stakeholder groups corresponding to both first (EV) and second life (stationary energy storage) battery applications. The environmental feasibility criterion was defined by an equivalent-functionality lead-acid (PbA) battery. A critical methodological challenge addressed was the allocation of environmental impacts associated with producing LIBs across the EV and stationary use systems. The model also tested sensitivity to parameters such as the fraction of battery cells viable for reuse, service life of refurbished cells, and PbA battery efficiency.Results and discussion
From the perspective of EV applications, cascading reuse of an LIB in stationary energy storage can reduce net cumulative energy demand and global warming potential by 15 % under conservative estimates and by as much as 70 % in ideal refurbishment and reuse conditions. When post-EV LIB cells were compared directly to a new PbA system for stationary energy storage, the reused cells generally had lower environmental impacts, except in scenarios where very few of the initial battery cells and modules could be reused and where reliability was low (e.g., life span of 1 year or less) in the secondary application.Conclusions
These findings demonstrate that EV LIB reuse in stationary application has the potential for dual benefit—both from the perspective of offsetting initial manufacturing impacts by extending battery life span as well as avoiding production and use of a less-efficient PbA system. It is concluded that reuse decisions and diversion of EV LIBs toward suitable stationary applications can be based on life cycle centric studies. However, technical feasibility of these systems must still be evaluated, particularly with respect to the ability to rapidly analyze the reliability of EV LIB cells, modules, or packs for refurbishment and reuse in secondary applications.155.
William R. T. Darwall Caroline M. Pollock Kevin G. Smith Jean-Christophe Vié 《Diversity & distributions》2008,14(1):159-160
De Silva et al . (2007) present an overview of the distribution and conservation status of the endemic freshwater fish of Asia. Within that review they use data from the IUCN Red List of Threatened Species™ (2006) to conduct an analysis of the conservation status of those endemic fish species. Their analysis is incorrect and provides a very misleading impression of the level of threat to Asian freshwater fish and to freshwater fish at the global scale. The errors stem from a misinterpretation of the data presented on the IUCN Red List. The sources of errors are discussed below and the opportunity is taken to clarify what the information on the IUCN Red List represents. 相似文献
156.
A virtual screening approach was used to identify new glycomimetics. The National Cancer Institute Diversity Set was docked into the carbohydrate binding site of the lectin concanavalin A (ConA). The resulting poses were analyzed and 19 molecules were tested for inhibition with an enzyme-linked lectin assay (ELLA). Eight of the 19 molecules inhibited ConA-carbohydrate binding. The two most potent inhibitors have IC(50) values that are an order of magnitude smaller than the monosaccharide methyl alpha-D-mannopyranoside. 相似文献
157.
158.
159.
160.