全文获取类型
收费全文 | 1169篇 |
免费 | 146篇 |
国内免费 | 81篇 |
出版年
2023年 | 19篇 |
2022年 | 33篇 |
2021年 | 45篇 |
2020年 | 35篇 |
2019年 | 62篇 |
2018年 | 43篇 |
2017年 | 42篇 |
2016年 | 44篇 |
2015年 | 39篇 |
2014年 | 86篇 |
2013年 | 100篇 |
2012年 | 46篇 |
2011年 | 93篇 |
2010年 | 54篇 |
2009年 | 44篇 |
2008年 | 57篇 |
2007年 | 48篇 |
2006年 | 46篇 |
2005年 | 49篇 |
2004年 | 37篇 |
2003年 | 26篇 |
2002年 | 27篇 |
2001年 | 21篇 |
2000年 | 19篇 |
1999年 | 20篇 |
1998年 | 22篇 |
1997年 | 19篇 |
1996年 | 20篇 |
1995年 | 21篇 |
1994年 | 15篇 |
1993年 | 18篇 |
1992年 | 17篇 |
1991年 | 10篇 |
1990年 | 15篇 |
1989年 | 17篇 |
1988年 | 21篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 11篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1976年 | 4篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1972年 | 2篇 |
排序方式: 共有1396条查询结果,搜索用时 328 毫秒
941.
VA菌根真菌、根瘤菌双接种对大豆增产效果的影响 总被引:1,自引:0,他引:1
本文论述了在自然状态下的土壤里,VA菌根真菌、根瘤菌双接种对大豆结瘤、菌根真菌侵染率、固氮酶活性及植株养分吸收状况的影响.研究结果表明,VA菌根真菌、根瘤菌双接种明显提高大豆结瘤能力与固氮酶活性,并可促进植物对养分的吸收,双接种比单接种VA菌根真菌处理提高产量140%,比单接种根瘤菌处理提高55.84%. 相似文献
942.
粪产碱菌对水稻根质子分泌作用及根际微生态的影响 总被引:1,自引:0,他引:1
用粪产碱菌浸种或沾根均能增强水稻根的质子分泌能力,促使介质酸化,pH值下降约2.2,浸种的效应更为明显。接种粪产碱菌能刺激水稻在缺铁胁迫条件下的质子分泌作用,提高根际溶液和根内ATP含量,同时增强根际土壤中铁、磷元素的有效性,促进植物根系对磷的吸收利用。 相似文献
943.
The effects of vesicular-arbuscular mycorrhizae inoculation on the growth of cacao seedlings (Theobroma cacao var. Ocumare 60) grown for 5 months in a nursery were studied. The effects of introduced VAM fungi (Glomus occultum, Acaulospora appendicula, Glomus manihotis, Acaulospora morrowae and Scutellospora pellucida) in soils treated with copper oxychloride or methyl bromide, were compared with the indigenous VAM and with their respective non-inoculated controls.Cacao seedlings responded well to indigenous VAM fungi, which included Scutellospora calospora as the dominant species, inducing increases significant in height, dry weight and foliar uptake of P, Cu and Zn in relation to the sterile control. G. occultum and A. appendicula increased the height of cacao seedlings but to an extent not yet statistically significant through the duration of the experiment. S. pellucida and A. appendicula doubled the phosphorus uptake of cacao seedlings. The methyl bromide sterilization induced the lowest Cu and Zn uptake in the cacao seedlings but this effect was ameliorated with VAM inoculation. Manifest deficiency symptoms were not observed in the treatments.Copper oxychloride treatment depressed growth to the same level as the sterile control although its residual effects did not kill VAM. It could change the competitive relations among the VAM species and in this case seemed to affect adversely the more efficient native fungi.The influence of the presence and long permanence of large cotyledons in cacao on the results obtained is discussed. 相似文献
944.
945.
Kentaro Minami Koji Kumagai Yoshinao Sugai Kohki Nakamura Shigeto Naito Shigeru Oshima 《Indian pacing and electrophysiology journal》2018,18(3):115-119
In patients with atrial fibrillation (AF) having congenital anatomical abnormalities, such as complete situs inversus and dextrocardia, pulmonary vein isolation (PVI) ablation can be performed safety using a three-dimensional electroanatomical mapping system. However, it is not clear whether a three-dimensional electroanatomical mapping system can be used to detect non-PV ectopic beats initiating AF in patients with complete situs inversus and dextrocardia. Here, we report a 21-year-old man with complete situs inversus and dextrocardia, who showed AF caused by non-PV ectopic beats. We successfully detected the origin of the triggered activity from the non-PV foci using three-dimensional electroanatomical mapping. 相似文献
946.
An evaluation of a double‐tailed deformity in a coral‐reef surgeonfish Acanthurus nigrofuscus (Acanthuridae) using micro‐computed tomography 下载免费PDF全文
X‐ray micro‐computed tomography scans were used to examine the caudal‐fin structure of an unusual double‐tailed deformity in an adult brown surgeonfish Acanthurus nigrofuscus from the Great Barrier Reef. In both this case and in a similar double‐tailed deformity in a juvenile Tomini surgeonfish Ctenochaetus tominiensis from the Philippines, the caudal fin was duplicated along the dorsoventral axis. Detailed examination of the A. nigrofuscus specimen revealed that the deformity was associated with duplication and reflection of the hypural plates and the posterior vertebrae, yet the fish survived to adulthood, indicating that the effects of duplication on survival may be limited. 相似文献
947.
Establishment of a new fish cell line from the caudal fin of golden pompano Trachinotus ovatus and its susceptibility to iridovirus 下载免费PDF全文
A new cell line derived from the caudal fin of golden pompano Trachinotus ovatus (TOCF) was successfully established and characterized. TOCF cells grew well at 28° C in L‐15 medium supplemented with 10% foetal bovine serum (FBS). The cell line has been subcultured in more than 100 passages. Molecular characterization of 18S ribosomal (r)RNA and cytochrome oxidase subunit 1 (COI) confirmed that the TOCF cells were derived indeed from T. ovatus. TOCF cells have a modal chromosome number of 54. It was further showed that TOCF cells were transfected successfully with pEGFP‐N3 and pDsRED‐N1 plasmid, suggesting that TOCF cells could be used to research gene functions in vitro. Viral susceptibility tests showed that TOCF cells were susceptible to Singapore grouper iridovirus (SGIV), observed by the occurrence of the cytopathic effect (CPE) with the formation of inclusion bodies. In addition, the expression of major capsid protein (MCP) gene of SGIV changed during virus infection in TOCF cells. Thus, our present results described the characteristic of a TOCF cell line that could be a valuable tool for genetic manipulation, as well as isolation and propagation of iridovirus studies. 相似文献
948.
949.
950.