全文获取类型
收费全文 | 33508篇 |
免费 | 3172篇 |
国内免费 | 226篇 |
专业分类
36906篇 |
出版年
2023年 | 156篇 |
2022年 | 325篇 |
2021年 | 605篇 |
2020年 | 447篇 |
2019年 | 566篇 |
2018年 | 682篇 |
2017年 | 622篇 |
2016年 | 903篇 |
2015年 | 1455篇 |
2014年 | 1460篇 |
2013年 | 1950篇 |
2012年 | 2189篇 |
2011年 | 2037篇 |
2010年 | 1425篇 |
2009年 | 1309篇 |
2008年 | 1726篇 |
2007年 | 1713篇 |
2006年 | 1553篇 |
2005年 | 1568篇 |
2004年 | 1555篇 |
2003年 | 1535篇 |
2002年 | 1591篇 |
2001年 | 625篇 |
2000年 | 517篇 |
1999年 | 579篇 |
1998年 | 476篇 |
1997年 | 349篇 |
1996年 | 357篇 |
1995年 | 356篇 |
1994年 | 300篇 |
1993年 | 271篇 |
1992年 | 387篇 |
1991年 | 360篇 |
1990年 | 290篇 |
1989年 | 315篇 |
1988年 | 251篇 |
1987年 | 260篇 |
1986年 | 224篇 |
1985年 | 278篇 |
1984年 | 270篇 |
1983年 | 219篇 |
1982年 | 250篇 |
1981年 | 252篇 |
1980年 | 202篇 |
1979年 | 212篇 |
1978年 | 207篇 |
1977年 | 185篇 |
1976年 | 164篇 |
1974年 | 146篇 |
1973年 | 154篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
Pierre Bongrand Gilles Bouvenot Robert Bartolin J Jeanne Tatossian Bernard Bruguerolle 《Chronobiology international》1988,5(1):81-83
Eleven male subjects were investigated to detect a possible circadian rhythm of the polymorphonuclear phagocytosis. Both cell activity and serum opsonins were studied for numerical detection of granulocytes having ingested at least one particle and for the mean number of ingested particles per cell. No significant temporal differences (ANOVA and cosinor) were found. 相似文献
52.
53.
54.
Pierre Livet 《PSN》2003,1(1):45-52
Every emotion can be characterized by its temporal dynamics, which also allow emotions to be categorised. Emotions, understood as resulting from the perception of a difference between expectations and the observed consequences of a course of action, are constantly interacting with cognitive processes that underlie these emotions and react to them. This is the case, in particular, for revision processes concerning one’s beliefs. In this view, anxiety can be understood as a signal of a difficulty to revise profoundly one’s beliefs, which explains the tendency to make only small revisions. Resistance to revision (of beliefs or preferences) can also be an indication of one’s values. It is mainly at the level of affective attitudes (with longer temporal scope and requiring deeper revisions) that mental diseases can be observed and can be described from the standpoint of their own strategies of revision. 相似文献
55.
56.
Véronique Lavoie Anne‐Elen Kernaleguen Guy Charron Nada Farhat Mariève Cossette Aida M. Mamarbachi Bruce G. Allen Eric Rhéaume Jean‐Claude Tardif 《Obesity (Silver Spring, Md.)》2011,19(4):722-728
Adiponectin is an adipokine whose plasma levels are inversely correlated to metabolic syndrome components. Adiponectin protects against atherosclerosis and decreases risks in myocardial infarction. Endothelial progenitor cells (EPCs) are a heterogeneous population of circulating cells involved in vascular repair and neovascularization. EPCs number is reduced in patients with cardiovascular disease. We hypothesize that the positive effects of adiponectin against atherosclerosis are explained in part by its interactions with EPCs. Cells were obtained from healthy volunteers' blood by mononuclear cell isolation and plating on collagen‐coated dishes. Three sub‐populations of EPCs were identified and characterized using flow cytometry. EPCs' expression of adiponectin receptors, AdipoR1, and AdipoR2 was evaluated by quantitative PCR. The effects of recombinant adiponectin on EPCs' susceptibility to apoptosis were assessed. Finally, expression of neutrophil elastase by EPCs and activity of this enzyme on adiponectin processing were assessed. Quantitative PCR analysis of EPCs mRNAs showed that AdipoR1 mRNA is expressed at higher levels than AdipoR2. Expression of AdipoR1 protein was confirmed by western blot. Adiponectin significantly increased survival of two sub‐populations of EPCs in conditions of serum deprivation. Such effect could not be demonstrated in the third EPCs sub‐population. We also demonstrated that EPCs, particularly one sub‐population, express neutrophil elastase. Neutrophil elastase activity was confirmed in EPCs' conditioned media. Adiponectin protects some EPCs sub‐populations against apoptosis and therefore could modulate EPCs ability to induce repair of vascular damage. Neutrophil elastase activity of EPCs could locally modulate adiponectin activity by its involvement in the generation of the globular form of adiponectin. 相似文献
57.
Effects of applications of municipal compost on uptake of copper,zinc and boron by garden vegetables
Summary Municipal compost applied to soils in plot experiments with cabbages, lettuces, beans, potatoes and peas in three successive years (25–100 tonnes per hectare) has produced significant enhancement of available soil Cu, Zn and B in each year. Associated significant increases in uptake were as follows: Cu, Zn and B with lettuces and beans, Zn and B with potatoes and B with peas. No significant increases in uptake of any of these elements was obtained in two experiments with cabbages.Compost treatment was associated with severe phytotoxic effects in the experiment with beans and with yield responses in the experiments with peas and potatoes. re]19721116 相似文献
58.
Six bisindole alkaloids have been isolated from the leaves of Dyera costulata (Apocynaceae). One is the known ochrolifuanine A and the others are the novel ochrolifuanines E and F, and the 18-dehydroochrolifuanines A, E and F. 相似文献
59.
60.
Jorge E. Ramos Gretta T. Pecl Natalie A. Moltschaniwskyj Jan M. Strugnell Rafael I. León Jayson M. Semmens 《PloS one》2014,9(8)
Understanding the response of any species to climate change can be challenging. However, in short-lived species the faster turnover of generations may facilitate the examination of responses associated with longer-term environmental change. Octopus tetricus, a commercially important species, has undergone a recent polewards range shift in the coastal waters of south-eastern Australia, thought to be associated with the southerly extension of the warm East Australian Current. At the cooler temperatures of a polewards distribution limit, growth of a species could be slower, potentially leading to a bigger body size and resulting in a slower population turnover, affecting population viability at the extreme of the distribution. Growth rates, body size, and life span of O. tetricus were examined at the leading edge of a polewards range shift in Tasmanian waters (40°S and 147°E) throughout 2011. Octopus tetricus had a relatively small body size and short lifespan of approximately 11 months that, despite cooler temperatures, would allow a high rate of population turnover and may facilitate the population increase necessary for successful establishment in the new extended area of the range. Temperature, food availability and gender appear to influence growth rate. Individuals that hatched during cooler and more productive conditions, but grew during warming conditions, exhibited faster growth rates and reached smaller body sizes than individuals that hatched into warmer waters but grew during cooling conditions. This study suggests that fast growth, small body size and associated rapid population turnover may facilitate the range shift of O. tetricus into Tasmanian waters. 相似文献