全文获取类型
收费全文 | 751篇 |
免费 | 35篇 |
国内免费 | 1篇 |
出版年
2021年 | 6篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 6篇 |
2016年 | 11篇 |
2015年 | 8篇 |
2014年 | 10篇 |
2013年 | 26篇 |
2012年 | 36篇 |
2011年 | 30篇 |
2010年 | 15篇 |
2009年 | 19篇 |
2008年 | 25篇 |
2007年 | 25篇 |
2006年 | 41篇 |
2005年 | 49篇 |
2004年 | 28篇 |
2003年 | 34篇 |
2002年 | 54篇 |
2001年 | 59篇 |
2000年 | 46篇 |
1999年 | 31篇 |
1998年 | 15篇 |
1997年 | 8篇 |
1996年 | 17篇 |
1995年 | 12篇 |
1994年 | 8篇 |
1992年 | 6篇 |
1991年 | 10篇 |
1990年 | 15篇 |
1989年 | 11篇 |
1988年 | 12篇 |
1987年 | 5篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 3篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 11篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 7篇 |
1971年 | 3篇 |
1970年 | 5篇 |
1969年 | 4篇 |
排序方式: 共有787条查询结果,搜索用时 31 毫秒
1.
Anthony J. Hesketh Caroline Maloney Christopher A. Behr Morris C. Edelman Richard D. Glick Yousef Al-Abed Marc Symons Samuel Z. Soffer Bettie M. Steinberg 《PloS one》2015,10(12)
Metastatic Ewing Sarcoma carries a poor prognosis, and novel therapeutics to prevent and treat metastatic disease are greatly needed. Recent evidence demonstrates that tumor-associated macrophages in Ewing Sarcoma are associated with more advanced disease. While some macrophage phenotypes (M1) exhibit anti-tumor activity, distinct phenotypes (M2) may contribute to malignant progression and metastasis. In this study, we show that M2 macrophages promote Ewing Sarcoma invasion and extravasation, pointing to a potential target of anti-metastatic therapy. CNI-1493 is a selective inhibitor of macrophage function and has shown to be safe in clinical trials as an anti-inflammatory agent. In a xenograft mouse model of metastatic Ewing Sarcoma, CNI-1493 treatment dramatically reduces metastatic tumor burden. Furthermore, metastases in treated animals have a less invasive morphology. We show in vitro that CNI-1493 decreases M2-stimulated Ewing Sarcoma tumor cell invasion and extravasation, offering a functional mechanism through which CNI-1493 attenuates metastasis. These data indicate that CNI-1493 may be a safe and effective adjuvant agent for the prevention and treatment of metastatic Ewing Sarcoma. 相似文献
2.
W. Maartin Strauss Robyn S. Hetem Duncan Mitchell Shane K. Maloney Leith C. R. Meyer Andrea Fuller 《PloS one》2015,10(2)
In artiodactyls, arterial blood destined for the brain can be cooled through counter-current heat exchange within the cavernous sinus via a process called selective brain cooling. We test the hypothesis that selective brain cooling, which results in lowered hypothalamic temperature, contributes to water conservation in sheep. Nine Dorper sheep, instrumented to provide measurements of carotid blood and brain temperature, were dosed with deuterium oxide (D2O), exposed to heat for 8 days (40◦C for 6-h per day) and deprived of water for the last five days (days 3 to 8). Plasma osmolality increased and the body water fraction decreased over the five days of water deprivation, with the sheep losing 16.7% of their body mass. Following water deprivation, both the mean 24h carotid blood temperature and the mean 24h brain temperature increased, but carotid blood temperature increased more than did brain temperature resulting in increased selective brain cooling. There was considerable inter-individual variation in the degree to which individual sheep used selective brain cooling. In general, sheep spent more time using selective brain cooling, and it was of greater magnitude, when dehydrated compared to when they were euhydrated. We found a significant positive correlation between selective brain cooling magnitude and osmolality (an index of hydration state). Both the magnitude of selective brain cooling and the proportion of time that sheep spent selective brain cooling were negatively correlated with water turnover. Sheep that used selective brain cooling more frequently, and with greater magnitude, lost less water than did conspecifics using selective brain cooling less efficiently. Our results show that a 50kg sheep can save 2.6L of water per day (~60% of daily water intake) when it employs selective brain cooling for 50% of the day during heat exposure. We conclude that selective brain cooling has a water conservation function in artiodactyls. 相似文献
3.
P C Maloney 《BioEssays : news and reviews in molecular, cellular and developmental biology》1992,14(11):757-762
This article summarizes the study of anion exchange mechanisms in bacteria. Along with defining at least two different families of anion exchange, an examination of such carrier-mediated antiport reactions has led to techniques that considerably broaden the scope of biochemical methods for examining membrane proteins. Such advances have been exploited to show that anion exchange itself forms the mechanistic base of an entirely new kind of proton pump, one which may shed light on a variety of bacterial events, including methanogenesis. Perhaps most important, the study of exchange provided the final link in a chain of evidence pointing to a structural 'rhythm' that seems to characterize membrane carriers. These three issues--a biochemical tool, a new proton pump, and a common structural rhythm--are briefly examined in the context of their origins in the analysis of bacterial anion exchange. 相似文献
4.
5.
6.
7.
A simple analysis was developed to compare granulocyte production in marrow with granulocyte turnover in peripheral blood of the dog. the analysis is anchored to the relative number of granulopoietic and erythropoietic cells that are flashlabeled with tritiated thymidine. This provides a convenient measure of relative production rates, since there is little, if any, difference in the duration of the respective DNA synthesis periods. the latter was confirmed in the present work by comparison of myeloid and erythroid cells in respect to (1) labeled mitosis curves and (2) changes in labeling intensity with constant infusion of tritiated thymidine. the ratio of flash-labeled granulocyte to erythrocyte progenitors was unity (1.02 ± 0.05) in the eight dogs studied, which means that gross production rates were essentially the same. Since net production as revealed by peripheral blood turnover is greater for erythrocytes than for granulocytes, it follows that there must be some ineffective granulopoiesis. This may correspond to over half of the total production. It is suggested that this phenomenon, which apparently occurs in man as well as in dog, could represent an important feature of granulocyte regulation. 相似文献
8.
A viable option for increasing nitrogen (N) use efficiency and mitigation of negative impacts of N on the environment is to capitalize on multi-element interactions through implementation of nutrient management programs that provide balanced nutrition. Numerous studies have demonstrated the immediate efficacy of this approach in the developing regions like China and India as well as developed countries in North America. Based on 241 site-years of experiments in these countries, the first-year N recovery efficiency (RE) for the conventional or check treatments averaged 21% while the balanced treatments averaged 54% RE, for an average increase of 33% in RE due to balanced nutrition. Effective policies to promote adoption are most likely those that enable site-specific approaches to nutrient management decisions rather than sweeping, nation-wide incentives supporting one nutrient over another. Local farmers, advisers and officials need to be empowered with tools and information to help them define necessary changes in practices to create more balanced nutrient management. 相似文献
9.
Tenzin Gayden Annabel Perez Patrice J. Persad Areej Bukhari Shilpa Chennakrishnaiah Tanya Simms Trisha Maloney Kristina Rodriguez Rene J. Herrera 《American journal of physical anthropology》2013,151(2):169-182
The Himalayan mountain range is strategically located at the crossroads of the major cultural centers in Asia, the Middle East and Europe. Although previous Y‐chromosome studies indicate that the Himalayas served as a natural barrier for gene flow from the south to the Tibetan plateau, this region is believed to have played an important role as a corridor for human migrations between East and West Eurasia along the ancient Silk Road. To evaluate the effects of the Himalayan mountain range in shaping the maternal lineages of populations residing on either side of the cordillera, we analyzed mitochondrial DNA variation in 344 samples from three Nepalese collections (Newar, Kathmandu and Tamang) and a general population of Tibet. Our results revealed a predominantly East Asian‐specific component in Tibet and Tamang, whereas Newar and Kathmandu are both characterized by a combination of East and South Central Asian lineages. Interestingly, Newar and Kathmandu harbor several deep‐rooted Indian lineages, including M2, R5, and U2, whose coalescent times from this study (U2, >40 kya) and previous reports (M2 and R5, >50 kya) suggest that Nepal was inhabited during the initial peopling of South Central Asia. Comparisons with our previous Y‐chromosome data indicate sex‐biased migrations in Tamang and a founder effect and/or genetic drift in Tamang and Newar. Altogether, our results confirm that while the Himalayas acted as a geographic barrier for human movement from the Indian subcontinent to the Tibetan highland, it also served as a conduit for gene flow between Central and East Asia. Am J Phys Anthropol 151:169–182, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
10.
Mark J. Mitton-Fry Steven J. Brickner Judith C. Hamel Lori Brennan Jeffrey M. Casavant Michael Chen Tao Chen Xiaoyuan Ding James Driscoll Joel Hardink Thuy Hoang Erbing Hua Michael D. Huband Meghan Maloney Anthony Marfat Sandra P. McCurdy Dale McLeod Michael Plotkin Christopher Zook 《Bioorganic & medicinal chemistry letters》2013,23(10):2955-2961
A structurally novel set of inhibitors of bacterial type II topoisomerases with potent in vitro and in vivo antibacterial activity was developed. Dual-targeting ability, hERG inhibition, and pharmacokinetic properties were also assessed. 相似文献