全文获取类型
收费全文 | 1299篇 |
免费 | 21篇 |
国内免费 | 113篇 |
出版年
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 8篇 |
2020年 | 11篇 |
2019年 | 20篇 |
2018年 | 20篇 |
2017年 | 20篇 |
2016年 | 23篇 |
2015年 | 13篇 |
2014年 | 32篇 |
2013年 | 60篇 |
2012年 | 35篇 |
2011年 | 41篇 |
2010年 | 20篇 |
2009年 | 42篇 |
2008年 | 53篇 |
2007年 | 61篇 |
2006年 | 60篇 |
2005年 | 44篇 |
2004年 | 54篇 |
2003年 | 52篇 |
2002年 | 88篇 |
2001年 | 56篇 |
2000年 | 65篇 |
1999年 | 63篇 |
1998年 | 44篇 |
1997年 | 55篇 |
1996年 | 46篇 |
1995年 | 34篇 |
1994年 | 31篇 |
1993年 | 23篇 |
1992年 | 29篇 |
1991年 | 47篇 |
1990年 | 13篇 |
1989年 | 12篇 |
1988年 | 10篇 |
1987年 | 11篇 |
1986年 | 11篇 |
1985年 | 20篇 |
1984年 | 22篇 |
1983年 | 12篇 |
1982年 | 10篇 |
1981年 | 13篇 |
1980年 | 18篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1973年 | 2篇 |
排序方式: 共有1433条查询结果,搜索用时 15 毫秒
141.
巧花兜兰——越南中部兰科一新种 总被引:1,自引:0,他引:1
在今年年初的一次访问云南南部的旅行中,笔者曾购得数苗小型的兜兰,据兰商称系采自越南中部,又叫越南黄花仔。此种兜兰的叶甚似小叶兜兰PaphiopedilumbarbigerumTangetWang和海伦兜兰Paph.helenaeAveryanov,但花却有着明显的不同。小叶兜兰的花大,直径达5.5~7cm;合萼片狭窄,其宽度仅为中萼片的1/2~3/5。海伦兜兰花纯黄色;花瓣线形或宽线形。而此种兜兰的花直径3~3.5cm,呈淡黄绿色,唇瓣表面、合萼片中脉下半部和花瓣的中脉及中脉上方一侧均有枣红色晕;合萼片宽度为中萼片的4/5;… 相似文献
142.
3种植物精油对霉菌的抑制作用 总被引:13,自引:0,他引:13
肉桂 ( Cinnamomum cassia Presl)别名连桂 ,属樟科樟属 ,常绿乔木 ,高 1 0~ 1 5m,多为栽培 ,主产于广西、广东等地 ,云南、福建等省亦有分布。人们可从其叶、枝或树皮、籽中提取精油 ,精油主要用于医药及食品香精[1 ] 。山苍子 [Litsea cubeba ( Lour.) Pers]别名山鸡椒、木姜子 ,属樟科木姜子属 ,落叶灌木和乔木 ,高 8~ 1 0 m,果期 7~ 8月份 ,我国长江以南各省都有分布。民间广泛使用水蒸汽蒸馏法 ,从其果实中提制精油 ,精油主要用于调配食品、化妆品香精 ,合成其它原料及维生素 [2 ]。丁子香 [Stzygium aromaticum( Linn.)Merr.et… 相似文献
143.
Takeo Horiguchi 《Phycological Research》1996,44(3):143-150
A new raphidophyte flagellate is described from the river mouth of the Daintree River, north-east Australia where there are extensive mangrove forests. The organism has two distinct phases: a club-shaped motile form, and a more or less spherical benthic non-motile form. The motile cell is metabolic and possesses 10–20 chloroplasts. The chloroplasts are imbricated, somewhat reminiscent of roofing tiles. A unique structure has been found at the posterior end of the cell. It is a tubular invagination, which consists of a single membrane supported by many small flattened vesicles. In addition, the structure is surrounded by many fibril-containing vesicles. The tubular invagination is different from both the contractile vacuoles and the pusules of dinoflagellates in both behavior and structure. Based on the possession of these unique features, it is concluded that the this mangrove flagellate should be described as a new species in a new genus and the name Haramonas dimorpha Horiguchi gen. et sp. nov. is proposed. 相似文献
144.
Michael Kleyer 《植被学杂志》1999,10(5):697-708
Abstract. In this study, plant functional types are understood as groups of plants with similar biological traits displaying significant optima or maxima on a gradient plane of resource supply and disturbance intensity. The biological traits refer to expansion, vegetative regeneration, generative reproduction, dispersal and seed bank longevity. 129 vegetation samples were taken in an agricultural landscape in southwestern Germany, covering a wide range of terrestrial vegetation types – but with the exception of forests and wetlands. For each site, also soil data were recorded. Mean daily soil moisture was estimated with a simple model. Soil moisture, balanced nitrogen supply and available phosphorus were combined into a factor ‘resource supply’. In addition, disturbance intensity was estimated for each site. This factor was based on (1) frequency of disturbance, (2) disturbance depth below or above the soil surface, and (3) proportion of the area affected by a discrete disturbance event. 30 plant groups with similar biological characteristics resulted from a cluster analysis, based on a compilation of 19 biological traits for a regional species pool. Logistic regression on a gradient plane of disturbance intensity and resource supply yielded response curves for 28 groups. The dependent variable was defined as the probability of encountering all members of a group in a sample. 17 groups display a significant response curve on the gradient plane. Plants with a potential for long- range dispersal are concentrated on sites with low or high disturbance intensities (e.g. fallow land, fields, lawns). On sites with medium disturbance intensity (e.g. meadows) and low to medium resource supply, small-range dispersal predominates. There are no distinct trends concerning seed bank longevity. The potential for vertical and lateral expansion increases with decreasing disturbance intensity. Only at medium disturbance intensities does vertical expansion correlate positively with resource supply. Rapid detachment of daughter individuals occurs more often on productive sites than on less productive sites. Diversity of groups with similar biological traits is highest on sites with medium disturbance intensities. 相似文献
145.
146.
147.
148.
149.
Tao Zuo Jinshuai Shan Yang Liu Rong Xie Xiaochun Yu Chen Wu 《Translational oncology》2018,11(2):346-352
N-Acetylgalactosaminyltransferase-14 (GALNT14) is a member of acetylgalactosaminyltransferases family. We have shown that GALNT14 could promote breast cancer cell invasion. However, the underlying molecular mechanism is unclear. Here, using yeast two hybrid, we find that EGF-containing fibulin-like extracellular matrix protein 2 (EFEMP2) interacts with GALNT14. Both in vitro and in vivo binding assays show that EFEMP2 is associated with GALNT14. Moreover, we find that GALNT14 mediates glycosylation of EFEMP2. EFEMP2 significantly increased the invasion ability of breast cancer cells including MCF-7 and MBA-MD-231 cells, and this phenomenon is suppressed by knockdown expression of GALNT14. In addition, the GALNT14-dependent O-glycosylation of EFEMP-2 regulates the stability of EFEMP-2 protein in breast cancer cells. Taken together, our results demonstrate a novel molecular mechanism underlying breast cancer invasion. 相似文献
150.
Nienke van Beek Daniel J. Klionsky Fulvio Reggiori 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》2018,1865(5):803-816
The catabolic process of macroautophagy, through the rapid degradation of unwanted cellular components, is involved in a multitude of cellular and organismal functions that are essential to maintain homeostasis. Those functions include adaptation to starvation, cell development and differentiation, innate and adaptive immunity, tumor suppression, autophagic cell death, and maintenance of stem cell stemness. Not surprisingly, an impairment or block of macroautophagy can lead to severe pathologies. A still increasing number of reports, in particular, have revealed that mutations in the autophagy-related (ATG) genes, encoding the key players of macroautophagy, are either the cause or represent a risk factor for the development of several illnesses. The aim of this review is to provide a comprehensive overview of the diseases and disorders currently known that are or could be caused by mutations in core ATG proteins but also in the so-called autophagy receptors, which provide specificity to the process of macroautophagy. Our compendium underlines the medical relevance of this pathway and underscores the importance of the eventual development of therapeutic approaches aimed at modulating macroautophagy. 相似文献