全文获取类型
收费全文 | 27957篇 |
免费 | 2397篇 |
国内免费 | 2533篇 |
出版年
2024年 | 37篇 |
2023年 | 217篇 |
2022年 | 321篇 |
2021年 | 984篇 |
2020年 | 840篇 |
2019年 | 1008篇 |
2018年 | 1029篇 |
2017年 | 832篇 |
2016年 | 1047篇 |
2015年 | 1632篇 |
2014年 | 2008篇 |
2013年 | 2214篇 |
2012年 | 2702篇 |
2011年 | 2425篇 |
2010年 | 1668篇 |
2009年 | 1445篇 |
2008年 | 1934篇 |
2007年 | 1669篇 |
2006年 | 1531篇 |
2005年 | 1292篇 |
2004年 | 1269篇 |
2003年 | 1129篇 |
2002年 | 1011篇 |
2001年 | 443篇 |
2000年 | 335篇 |
1999年 | 274篇 |
1998年 | 264篇 |
1997年 | 157篇 |
1996年 | 146篇 |
1995年 | 145篇 |
1994年 | 108篇 |
1993年 | 91篇 |
1992年 | 85篇 |
1991年 | 72篇 |
1990年 | 54篇 |
1989年 | 60篇 |
1988年 | 45篇 |
1987年 | 46篇 |
1986年 | 37篇 |
1985年 | 43篇 |
1984年 | 16篇 |
1983年 | 20篇 |
1982年 | 27篇 |
1981年 | 11篇 |
1979年 | 14篇 |
1978年 | 10篇 |
1977年 | 12篇 |
1976年 | 10篇 |
1975年 | 9篇 |
1973年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 553 毫秒
951.
Xiao‐Jun Zhou Li Ma Wen‐Zhe Liu 《Botanical journal of the Linnean Society. Linnean Society of London》2016,180(4):504-514
Tapiscia sinensis, a rare endemic woody plant with both male and hermaphrodite individuals, is distributed in southern China. Whether T. sinensis is functionally androdioecious is unknown. In this study, we compare the male fitness between male and hermaphrodite individuals and perform pollination experiments in different habitats, identify the ability of actual siring of pollen from hermaphrodites and males under natural pollination, and discuss the evolution and maintenance of androdioecy in T. sinensis. Research suggests that flowers and fruits grow synchronously on hermaphrodite plants of T. sinensis from April to June. The males of T. sinensis had more than twice the genetic contribution of hermaphrodites through their male function and the fruit set from male pollination and cross‐pollination was the highest in all of the treatments, whereas that from self‐pollination was the lowest. Additionally, paternity analysis showed that the hermaphroditic pollen could result in siring success under natural pollination. The results showed that T. sinensis is a functionally androdioecious tree, that male individuals might evolve from a hermaphroditic ancestor and that the synchronous growth of flowers and fruit in hermaphrodites might facilitate the evolution and maintenance of androdioecy in T. sinensis. 相似文献
952.
953.
954.
ángela María Sánchez-López Abdellatif Bahaji Nuria De Diego Marouane Baslam Jun Li Francisco José Mu?oz Goizeder Almagro Pablo García-Gómez Kinia Ameztoy Adriana Ricarte-Bermejo Ond?ej Novák Jan F. Humplík Luká? Spíchal Karel Dole?al Sergio Ciordia María Carmen Mena Rosana Navajas Edurne Baroja-Fernández Javier Pozueta-Romero 《Plant physiology》2016,172(3):1989-2001
955.
956.
957.
958.
Yoshihisa Shimizu Chiaki Yoshikawa Junji Suzuki Jun Qiu Edith van den Bosch 《Biotechnology letters》2016,38(3):403-408
Objective
When polymer brushes are applied as the inner coating for artificial blood vessels, they may induce unwanted responses in vascular endothelial cells continuously exposed to the polymer surface. Accordingly, we have examined the in vitro effect of non-biofouling concentrated polymer brushes (CPBs) on pro-inflammatory and angiogenic responses of human umbilical vein endothelial cells (HUVECs).Results
Micro-patterned CPBs were prepared on silicon wafers using biocompatible polymers, poly(poly(ethylene glycol)methyl ether methacrylate) (PPEGMA) and poly(2-hydroxyethyl methacrylate) (PHEMA). HUVECs were cultured on PPEGMA-CPBs and PHEMA-CPBs with different channel widths (20, 50, and 80 µm) and analyzed for mRNA expression of the pro-inflammatory cytokines IL-6 and IL-8 and angiogeneic vascular endothelial growth factor (VEGF). Irrespective of channel width, PHEMA-CPBs reduced the expression of all target genes, whereas PPEGMA-CPBs reduced VEGF and did not affect IL-6 and IL-8 levels.Conclusion
Micro-patterned CPBs, irrespective of chemical structure or adhesion area, do not induce the expression of important pro-inflammatory and angiogenic mediators in endothelial cells.959.
Jun Feng Su Sheng Chen Zheng Ting Lin Huang Fang Ma Si Cheng Shao Shao Fei Yang 《Geomicrobiology journal》2016,33(7):586-591
A novel bacterium, strain SZ28, identified as Acinetobacter sp., showed anaerobic denitrification ability using Mn(II) as the electron donor. Nitrate-nitrogen concentration decreased from nearly 16.52–mg L?1 to 4.4–mg L?1, without accumulation of nitrite as an intermediate, with a maximum of 0.063–mg NO3?-N L?1 h?1, reaching a peak of 0.085–mg NO3?-N L?1 h?1 in sodium acetate. The nitrate removal rate reached 0.067–mg NO3?-N L?1 h?1, 0.059–mg NO3?-N L?1 h?1, and 0.078 mg NO3?-N L?1 h?1 using Mn(II), S(II), and Fe(II) as electron donors, respectively. The optimum pH was 6.0, with a removal rate of 0.063–mg NO3?-N L?1 h?1 相似文献
960.