全文获取类型
收费全文 | 2305篇 |
免费 | 160篇 |
出版年
2023年 | 17篇 |
2022年 | 38篇 |
2021年 | 61篇 |
2020年 | 35篇 |
2019年 | 75篇 |
2018年 | 79篇 |
2017年 | 64篇 |
2016年 | 82篇 |
2015年 | 137篇 |
2014年 | 126篇 |
2013年 | 149篇 |
2012年 | 216篇 |
2011年 | 207篇 |
2010年 | 119篇 |
2009年 | 95篇 |
2008年 | 145篇 |
2007年 | 129篇 |
2006年 | 124篇 |
2005年 | 95篇 |
2004年 | 89篇 |
2003年 | 68篇 |
2002年 | 64篇 |
2001年 | 15篇 |
2000年 | 16篇 |
1999年 | 13篇 |
1998年 | 14篇 |
1997年 | 7篇 |
1996年 | 17篇 |
1995年 | 14篇 |
1994年 | 9篇 |
1993年 | 11篇 |
1992年 | 14篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 9篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 9篇 |
1984年 | 7篇 |
1982年 | 11篇 |
1981年 | 6篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1969年 | 4篇 |
1968年 | 5篇 |
1964年 | 4篇 |
排序方式: 共有2465条查询结果,搜索用时 46 毫秒
1.
2.
Paloma Rocha Arakaki Paula Andrea Borges Salgado Joo Diego de Agostini Losano Dbora Rodrigues Gonalves Rodrigo del Rio do Valle Ricardo Jos Garcia Pereira Marcilio Nichi 《American journal of primatology》2019,81(12)
Wild animal genetic resource banking (GRB) represents a valuable tool in conservation breeding programs, particularly in cases involving endangered species such as the golden‐headed lion tamarin (Leontopithecus chrysomelas). Thus, we aimed to assess a sperm freezing protocol for golden‐headed lion tamarins using two different exenders: BotuBOV® (BB) and Test Yolk Buffer® (TYB). Ejaculates were collected by penile vibrostimulation from animals housed at São Paulo Zoological Park Foundation, São Paulo, Brazil, and after immediate analysis, two aliquots were diluted in BB and TYB. Postthawing samples were evaluated for total and progressive motility, plasma membrane and acrosome integrities, mitochondrial activity, susceptibility to oxidative stress, and sperm–egg‐binding. No differences between BB and TYB were found for most seminal parameters, except for acrosome integrity and susceptibility to oxidative stress (in both cases BB showed higher values). However, in spite of these differences and regardless of the extender used, postthaw sperm motility and viability with the described protocol were encouraging (on average >50% and >80%, respectively), indicating that sperm cryopreservation may be a short‐term measure for the conservation of golden‐headed lion tamarins. 相似文献
3.
4.
5.
6.
7.
L D'Agostino S Pignata B Daniele R Ventriglia G Ferrari C Ferraro S Spagnuolo P E Lucchelli G Mazzacca 《Biochimica et biophysica acta》1989,993(2-3):228-232
Plasma diamine oxidase (DAO) values are enhanced by intravenous injection of heparin which releases the enzyme, synthesized in small bowel enterocytes, from binding sites located on endothelial cells of the intestinal microvasculature. Intestinal DAO, in analogy with lipoprotein lipase (another heparin-released enzyme), is believed to be electrostatically linked to endothelial binding sites composed of a glycosaminoglycan (GAG) which is presumably heparan sulphate, but the complete mechanism of enzyme release is not known. In this study we assayed in rats the DAO-releasing capability of heparan sulphate, dermatan sulphate, chondroitin sulphate A and hyaluronic acid, all heparin related compounds. Heparan sulphate, a compound with the same hexosamine as heparin but with a lower concentration of sulphated iduronic acid, induced a very high release of DAO (3-fold less than heparin), while the other tested GAGs, composed of higher proportions of non sulphated uronic acid and with galactosamine instead of glucosamine, induced a significantly lower release. In rats treated with 60 mg heparan sulphate the significant decrease in ileal mucosal DAO activity indicates that, in analogy with heparin, the high plasma enzymatic activity induced is of enterocytic origin. It is suggested that the high charge density of the compounds tested, due to the degree of sulphatation, is the decisive factor in promoting the release of intestinal DAO. 相似文献
8.
Daniele Arobba Andrea Quaglia Paolo Panagia Paolo Minuti Sergio Innocenti Pier Luigi Odda 《Aerobiologia》1988,4(1-2):38-46
Riassunto Sono state rilevate durante un monitoraggio aerobiologico effettuato a Pietra Ligure (Savona) nel corso del 1987 le concentrazioni
polliniche di 50 taxa ed è stata valutata l'influenza relativa dei fattori meteorologici. Le osservazioni palinologiche sono
state rapportate alle concentrazioni sieriche delle IgE specifiche, alla reattività bronchiale specifica ed aspecifica valutate
in 101 pazienti allergici (rinitici ed asmatici), sensibilizzati a Graminaceae ed Urticaceae (Parietaria) al fine di riconoscere
correlazioni tra le caratteristiche aerobiologiche di questi allergeni edi meccanismi patogenetici che sostengono la reattività
bronchiale.
相似文献
9.
Arsenio Corrado Negrini Renato Ariano Guiseppina Delbono Antonio Ebbli Antonio Quaglia Daniele Arobba 《Aerobiologia》1992,8(3):355-358
Summary The authors examined 734 sensitised patients living in four localities in Liguria (Genoa, Savona, Pietra Ligure and Sanremo). The commonest source of sensitisation (62.7%) was Urticaceae (Parietaria), followed by Poaceae (52.5%) andOlea europaea L. (24.0%). A survey of airborne pollens revealed a greater presence of Urticaceae and Poaceae in Genoa and of Oleaceae in Pietra Ligure and Sanremo. 相似文献
10.