全文获取类型
收费全文 | 1965篇 |
免费 | 166篇 |
出版年
2023年 | 16篇 |
2022年 | 18篇 |
2021年 | 77篇 |
2020年 | 40篇 |
2019年 | 46篇 |
2018年 | 48篇 |
2017年 | 45篇 |
2016年 | 80篇 |
2015年 | 116篇 |
2014年 | 118篇 |
2013年 | 151篇 |
2012年 | 182篇 |
2011年 | 156篇 |
2010年 | 102篇 |
2009年 | 87篇 |
2008年 | 105篇 |
2007年 | 108篇 |
2006年 | 119篇 |
2005年 | 89篇 |
2004年 | 83篇 |
2003年 | 58篇 |
2002年 | 55篇 |
2001年 | 15篇 |
2000年 | 11篇 |
1999年 | 11篇 |
1998年 | 17篇 |
1997年 | 11篇 |
1996年 | 13篇 |
1995年 | 10篇 |
1994年 | 10篇 |
1993年 | 9篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1986年 | 9篇 |
1985年 | 3篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1973年 | 5篇 |
1971年 | 7篇 |
1968年 | 3篇 |
1963年 | 3篇 |
1933年 | 2篇 |
1932年 | 2篇 |
1924年 | 2篇 |
排序方式: 共有2131条查询结果,搜索用时 15 毫秒
1.
2.
3.
l-Prolyl-l-leucyl-glycinamide is rapidly hydrolyzed by hypothalamic, hypophyseal and cortical homogenates from male or female rats. The peptidase activity is higher in the pituitary followed in decreasing order by the hypothalamus and the cerebral cortex. It is mostly localized in the supernatant fraction of a 100,000 g centrifugation and is inhibited by bacitracin.Tissues from female rats are half as active as those from male rats and show variations during the estrous cycle, with very low PLG metabolism at diestrus 1 in pituitary and hypothalamus. In contrast, the cerebral cortex at proestrus and estrus has significant lower hydrolyzing activity than at diestrus. No change of the peptidase activity is observed in tissues from ovariectomized animals after treatment with estrogen or progesterone.The results obtained suggest the existence of a correlation between peptidasic activity and melanotropin secretion. 相似文献
4.
5.
Patterns of Sleeping Site and Sleeping Tree Selection by Black-and-Gold Howler Monkeys (Alouatta caraya) in Northern Argentina 总被引:1,自引:0,他引:1
Brividoro Melina V. Kowalewski Martin M. Scarry Clara J. Oklander Luciana I. 《International journal of primatology》2019,40(3):374-392
International Journal of Primatology - The selection of sleeping sites and sleeping trees in nonhuman primates is related to social and ecological factors. We investigate the role of body... 相似文献
6.
Plant Ecology - Due to increased reserves available to face adverse conditions, drought tolerance should increase with seed size. This has been confirmed in the laboratory, but under field... 相似文献
7.
Marta Tejera-Alhambra Armanda Casrouge Clara de Andrés Ansgar Seyfferth Rocío Ramos-Medina Bárbara Alonso Janet Vega Lidia Fernández-Paredes Matthew L. Albert Silvia Sánchez-Ramón 《PloS one》2015,10(6)
Multiple sclerosis, the most common cause of neurological disability in young population after trauma, represents a significant public health burden. Current challenges associated with management of multiple sclerosis (MS) patients stem from the lack of biomarkers that might enable stratification of the different clinical forms of MS and thus prompt treatment for those patients with progressive MS, for whom there is currently no therapy available. In the present work we analyzed a set of thirty different plasma cytokines, chemokines and growth factors present in circulation of 129 MS patients with different clinical forms (relapsing remitting, secondary progressive and primary progressive MS) and 53 healthy controls, across two independent cohorts. The set of plasma analytes was quantified with Luminex xMAP technology and their predictive power regarding clinical outcome was evaluated both individually using ROC curves and in combination using logistic regression analysis. Our results from two independent cohorts of MS patients demonstrate that the divergent clinical and histology-based MS forms are associated with distinct profiles of circulating plasma protein biomarkers, with distinct signatures being composed of chemokines and growth/angiogenic factors. With this work, we propose that an evaluation of a set of 4 circulating biomarkers (HGF, Eotaxin/CCL11, EGF and MIP-1β/CCL4) in MS patients might serve as an effective tool in the diagnosis and more personalized therapeutic targeting of MS patients. 相似文献
8.
9.
10.
Sara Teller Clara Granell Manlio De Domenico Jordi Soriano Sergio Gómez Alex Arenas 《PLoS computational biology》2014,10(9)
The analysis of the activity of neuronal cultures is considered to be a good proxy of the functional connectivity of in vivo neuronal tissues. Thus, the functional complex network inferred from activity patterns is a promising way to unravel the interplay between structure and functionality of neuronal systems. Here, we monitor the spontaneous self-sustained dynamics in neuronal cultures formed by interconnected aggregates of neurons (clusters). Dynamics is characterized by the fast activation of groups of clusters in sequences termed bursts. The analysis of the time delays between clusters'' activations within the bursts allows the reconstruction of the directed functional connectivity of the network. We propose a method to statistically infer this connectivity and analyze the resulting properties of the associated complex networks. Surprisingly enough, in contrast to what has been reported for many biological networks, the clustered neuronal cultures present assortative mixing connectivity values, meaning that there is a preference for clusters to link to other clusters that share similar functional connectivity, as well as a rich-club core, which shapes a ‘connectivity backbone’ in the network. These results point out that the grouping of neurons and the assortative connectivity between clusters are intrinsic survival mechanisms of the culture. 相似文献