全文获取类型
收费全文 | 100287篇 |
免费 | 812篇 |
国内免费 | 884篇 |
专业分类
101983篇 |
出版年
2023年 | 79篇 |
2022年 | 149篇 |
2021年 | 236篇 |
2020年 | 163篇 |
2019年 | 243篇 |
2018年 | 12016篇 |
2017年 | 10844篇 |
2016年 | 7715篇 |
2015年 | 1033篇 |
2014年 | 710篇 |
2013年 | 864篇 |
2012年 | 4786篇 |
2011年 | 13390篇 |
2010年 | 12335篇 |
2009年 | 8530篇 |
2008年 | 10199篇 |
2007年 | 11722篇 |
2006年 | 623篇 |
2005年 | 832篇 |
2004年 | 1242篇 |
2003年 | 1277篇 |
2002年 | 1016篇 |
2001年 | 334篇 |
2000年 | 217篇 |
1999年 | 78篇 |
1998年 | 58篇 |
1997年 | 71篇 |
1996年 | 52篇 |
1995年 | 36篇 |
1994年 | 27篇 |
1993年 | 56篇 |
1992年 | 54篇 |
1991年 | 65篇 |
1990年 | 28篇 |
1989年 | 22篇 |
1988年 | 40篇 |
1987年 | 28篇 |
1984年 | 24篇 |
1983年 | 33篇 |
1982年 | 16篇 |
1981年 | 21篇 |
1980年 | 15篇 |
1977年 | 12篇 |
1976年 | 15篇 |
1975年 | 16篇 |
1972年 | 248篇 |
1971年 | 275篇 |
1965年 | 13篇 |
1962年 | 25篇 |
1944年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Takahiro Ishii Tatsufumi Okino Yosuke Mino Hiroaki Tamiya Fuyuhiko Matsuda 《Plant Growth Regulation》2007,52(2):131-139
Starfish waste has been shown to be an effective compost material not only in the promotion of plant growth but also in terms
of having insecticidal activity. In the present study, plant growth regulation by chemicals from starfish was examined. The
aqueous fraction from a hot water extract of the starfish Asterias amurensis Lütken showed plant-growth activity, while the aqueous fraction from a methanol extract inhibited growth of Brassica campestris. The lipophilic fraction from the methanol extract also exhibited a plant growth-promoting effect. The active components
from each extract were identified. Asterubine from the hot water extract promoted plant growth. A ceramide from the lipophilic
fraction showed root growth promoting effect, and three glucocerebrosides had promotive effects on the entire plant. Asterosaponins
were identified as the main growth inhibitors in the aqueous fraction of the methanol extract. These active compounds from
starfish waste could be analyzed as potential plant growth regulators in agricultural applications in the future. 相似文献
102.
This editorial addresses the debate concerning the origin of adult nucleus pulposus cells in the light of profiling studies
by Minogue and colleagues. In their report of several marker genes that distinguish nucleus pulposus cells from other related
cell types, the authors provide novel insights into the notochordal nature of the former. Together with recently published
work, their work lends support to the view that all cells present within the nucleus pulposus are derived from the notochord.
Hence, the choice of an animal model for disc research should be based on considerations other than the cell loss and replacement
by non-notochordal cells. 相似文献
103.
There are an increasing number of studies that are now focussing on the influence of climate change on species’ distributions. However, access to predictive climatic datasets for future scenarios is difficult due to their specific formats and/or the need to be geographically downscaled. The TYN dataset is freely available to users and provides a synthetic format with several climatic models and IPCC future climate scenarios. Moreover, the CRU historical dataset (1901–2000) is also available which allows users to create baseline models for current climatic variables. E‐clic is a free, user‐friendly software package that offers three different ways to convert these two datasets into a spatially explicit raster format which is compatible with the most common geographic information systems and usable on different platforms. 相似文献
104.
105.
Kevin B. Potts 《Journal of Mammalian Evolution》2010,17(3):221-222
106.
107.
108.
Background
Arsenic contamination is widespread throughout the world and this toxic metalloid is known to cause cancers of organs such as liver, kidney, skin, and lung in human. In spite of a recent surge in arsenic related studies, we are still far from a comprehensive understanding of arsenic uptake, detoxification, and sequestration in plants. Crambe abyssinica, commonly known as 'abyssinian mustard', is a non-food, high biomass oil seed crop that is naturally tolerant to heavy metals. Moreover, it accumulates significantly higher levels of arsenic as compared to other species of the Brassicaceae family. Thus, C. abyssinica has great potential to be utilized as an ideal inedible crop for phytoremediation of heavy metals and metalloids. However, the mechanism of arsenic metabolism in higher plants, including C. abyssinica, remains elusive. 相似文献109.
G. Matthew Hebdon Harry Le Vine Naji E. Sahyoun Claus J. Schmitges Pedro Cuatrecasas 《Life sciences》1980,26(17):1385-1396
3T3C2 mouse fibroblasts rendered permeable to (α?32P)NAD+ show cholera toxin-dependent labeling of a 45,000 m.w. protein and of a doublet of polypeptides around 52,000 m.w. These same bands are ADP-ribosylated in broken cells. Membranes prepared from pigeon erythrocytes pretreated with choleragen show a decrease in subsequent cholera toxin-specific ADP-ribosylation of a 43,000 m.w. polypeptide. Both whole cell and broken cell adenylate cyclase activation and toxin-specific ADP-ribosylation are reversed specifically by low pH and high concentrations of toxin and nicotinamide in all systems. Thus ADP-ribosylation appears to be relevant to the molecular action of choleragen in whole cells as well as in broken cells. 相似文献
110.