全文获取类型
收费全文 | 280篇 |
免费 | 7篇 |
专业分类
林业 | 43篇 |
农学 | 10篇 |
基础科学 | 1篇 |
65篇 | |
综合类 | 12篇 |
农作物 | 17篇 |
水产渔业 | 32篇 |
畜牧兽医 | 85篇 |
园艺 | 6篇 |
植物保护 | 16篇 |
出版年
2023年 | 1篇 |
2022年 | 6篇 |
2021年 | 3篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 6篇 |
2017年 | 3篇 |
2016年 | 10篇 |
2015年 | 8篇 |
2014年 | 9篇 |
2013年 | 27篇 |
2012年 | 18篇 |
2011年 | 25篇 |
2010年 | 10篇 |
2009年 | 14篇 |
2008年 | 23篇 |
2007年 | 19篇 |
2006年 | 19篇 |
2005年 | 14篇 |
2004年 | 15篇 |
2003年 | 15篇 |
2002年 | 13篇 |
2001年 | 10篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1980年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有287条查询结果,搜索用时 31 毫秒
281.
Hashimoto S Ohsumi K Tsuji Y Harauma N Miyata Y Fukuda A Hosoi Y Iritani A Morimoto Y 《The Journal of reproduction and development》2007,53(2):379-384
The aim of this study was to establish a culture system to improve the meiotic competence of porcine oocyte-granulosa cell complexes (OGCs) obtained from preantral or early antral follicles. Porcine OGCs were recovered from follicles with diameters of 230-300 (preantral follicles), 300-500, and 500-700 mum (early antral follicles) using scalpels. The OGCs were cultured for 2 weeks in culture medium. We examined the effects of the sizes of the follicles from which OGCs were recovered, the concentrations of polyvinylpyrrolidone (PVP, 0-8%) in the culture medium, and 2 types of culture dish (Falcon 3002 vs 1007) on formation of the antrum of OGCs. After culture, the oocytes were matured for 44 h to assess their meiotic competence. OGCs recovered from small follicles (230-500 microm) required longer (P<0.05) than larger follicles to form the antrum structure. The percentage of OGCs forming the antrum structure that were cultured in 2% PVP (31%) was higher (P<0.05) than for those cultured in other PVP concentrations (0-11%). The percentages of antrum-structure formation for OGCs cultured on Falcon 3002 (83% for 2% PVP and 60% for 4% PVP) were higher (P<0.05) than those cultured on Falcon 1007 (47% for 2% PVP and 9% for 4% PVP). Furthermore, all of the intact oocytes that were obtained from culture of OGCs and that formed an antrum were in the GV stage (n=28). When these immature oocytes were cultured for 44 h, the percentage of oocytes that reached the metaphase II stage (25%, n=68) was higher (P<0.0001) than that of oocytes matured without culture (0.7%, n=137). The results of the present study show that porcine OGCs obtained from preantral or early antral follicles acquire meiotic competence in vitro. 相似文献
282.
283.
Stefan Bräger Stephen M. Dawson Elisabeth SlootenSusan Smith Gregory S. StoneAusten Yoshinaga 《Biological conservation》2002,108(3):281-287
To document site fidelity and the alongshore range of individual Hector's dolphins we analysed sightings of 32 photographically identified dolphins, each seen ?10 times at Banks Peninsula, New Zealand, between 1985 and 1997. The furthest two sightings of an individual were 106 km apart. All other individuals ranged over less than 60 km (x?=31.0 km, SE=2.43) of coastline. Gender did not significantly influence alongshore range (female x?=30.4 km, SE =3.21, n=18; male x?=27.4 km, SE=5.68, n=5). Site fidelity was high: for example, on average, individuals were seen in Akaroa Harbour for about two thirds of the years they were known to be alive. These data suggest that impacts on Hector's dolphins are most appropriately managed on a small spatial scale. 相似文献
284.
285.
Germination response in wheat grains to dihydroactinidiolide,a germination inhibitor in wheat husks,and related compounds 总被引:2,自引:0,他引:2
Kato T Imai T Kashimura K Saito N Masaya K 《Journal of agricultural and food chemistry》2003,51(8):2161-2167
On the basis of our recent findings that the germination of intact wheat grains with glumes (husks) belonging to dormant varieties was restrained as compared with that of dehusked grains, we have explored the identities of germination inhibitors in the glumes, resulting in the characterization of dihydroactinidiolide (1) and some aromatic compounds. A related natural product, tetrahydroactinidiolide (2), showed similar activity. The present study has demonstrated that the sensitivity in inhibition response of germination of the grains to 1 and 2 declined during after-ripening, in parallel with changes in germinability; the sprouting of after-ripened seeds on a whole spike was preventable by exogenous application of 2 in laboratory conditions, and germination of after-ripened grains was delayed by more than two weeks by the action of 1 or 2. The term "pseudodormancy" is proposed for the phenomenon of delay of germination caused by the inhibitor. After accumulation of additional evidence on inhibition response of actinidiolide-type natural products, structurally related to inhibitor 1, a mechanism concerning germination inhibition by 1 or 2 is proposed on the basis of the concept of nonbonding interaction with the inhibitors at an active site of an acceptor. 相似文献
286.
In Okinawa, red soil runoff emerged as a social problem long ago, and many control measures have been adopted. However, their
effect has been gauged as insufficient. So, models to predict red soil runoff are required. Within this context, we have been
developing the suspended sediment concentration (SSC) analysis model. In this study, the SSC analysis model, a lumped storage-type
runoff model that includes a sediment runoff process, has been applied to two watersheds with different circumstances of land
use. In the application of this model, we tried to do a multi-objective optimization and examined some policies concerning
the choice of parameter sets. As a result, we were able to conclude that the SSC analysis model produced a good agreement
between the calculated value and the observed value. In multi-objective optimization, the relation between the root mean square
error (RMSE) of discharge and SSC became the Pareto relation. Moreover, it was recognized that, in taking into consideration
the viewpoint of the RMSE of sediment load and the total sediment load error, the optimization of discharge should be regarded
as important in choosing the set of parameters in an actual application. 相似文献
287.