全文获取类型
收费全文 | 901篇 |
免费 | 87篇 |
专业分类
988篇 |
出版年
2023年 | 7篇 |
2022年 | 15篇 |
2021年 | 20篇 |
2020年 | 15篇 |
2019年 | 17篇 |
2018年 | 20篇 |
2017年 | 18篇 |
2016年 | 20篇 |
2015年 | 48篇 |
2014年 | 44篇 |
2013年 | 58篇 |
2012年 | 89篇 |
2011年 | 74篇 |
2010年 | 54篇 |
2009年 | 36篇 |
2008年 | 52篇 |
2007年 | 44篇 |
2006年 | 43篇 |
2005年 | 42篇 |
2004年 | 39篇 |
2003年 | 42篇 |
2002年 | 29篇 |
2001年 | 10篇 |
2000年 | 4篇 |
1999年 | 8篇 |
1998年 | 12篇 |
1997年 | 8篇 |
1996年 | 11篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1980年 | 2篇 |
1978年 | 7篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1975年 | 6篇 |
1974年 | 3篇 |
1973年 | 6篇 |
1969年 | 2篇 |
1967年 | 2篇 |
排序方式: 共有988条查询结果,搜索用时 0 毫秒
981.
P Douzou E Campion G Hui Bon Hoa 《Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie》1987,304(3):71-75
Gelated networks of biopolymers submitted to thermal cycles may undergo phase-transitions and phase-separations, and their cryobehavior is chiefly associated with such phenomena. The properties unveiled with models on a macroscopic scale may have implications in the cryobehavior of living systems while the lability of biopolymer gels under the influence of other external conditions may be involved in a number of biological functions. 相似文献
982.
983.
984.
985.
A postal questionnaire study was carried out in an urban general practice to determine the effect of the introductory letter being sent by the participants'' own general practitioner compared with that from a letter sent directly from a research unit. By sequential sampling 409 individuals aged between 40 and 59 were assigned to one of two groups. The people in one group were written to by their own general practitioner and those in the other by a doctor from a research unit. Husbands and wives were paired and were always sent the same letter. A second letter was sent to nonresponders after one month. The response rate to the general practitioner was significantly higher than that to the doctor in the research unit (85% compared with 75%) and differed by age and sex. The results have important implications for other research workers and suggest that general practitioners are in a key position in the conduct of medical and epidemiological research. 相似文献
986.
987.
988.
Cong Zhou Zhaohui Guo Chi Peng Peng Zeng Ataa Fosua Bridget 《International journal of phytoremediation》2021,23(1):80-88
Abstract A sand hydroponic experiment with different concentrations of 0, 5, 10, 20, 40?mg L?1 Cd was used to study the growth and physiological response of Hylotelephium spectabile (Boreau) H. Ohba. and its phytoextraction potential for Cd. The results showed that total plant biomass under 5?mg L?1 Cd treatment was slightly affected. The content of malondialdehyde (MDA) in leaf exposed to Cd was higher, and the POD and CAT activity exhibited a positive response to the low level of Cd addition (5?mg·L?1). The photosynthesis pigments were slightly inhibited, and the ultrastructure of chloroplast remained intact after treatment with 10?mg L?1 Cd. The maximum leaf Cd content (603?mg·kg?1) was found in 5?mg L?1 Cd treatment, then decreased with the Cd level increased. The maximum Cd content in the shoots far exceeds the threshold level (100?mg kg?1) for a Cd-hyperaccumulator plant with the value of translocation factor (TFshoot/root) for Cd reaching up to 5.62. In conclusion, H. spectabile showed normal growth and physiological response and high shoot Cd accumulation under 5?mg L?1 Cd stress, which made it to be a good candidate for phytoextraction of low-level Cd polluted environment. 相似文献