全文获取类型
收费全文 | 952篇 |
免费 | 43篇 |
国内免费 | 65篇 |
出版年
2023年 | 11篇 |
2022年 | 17篇 |
2021年 | 23篇 |
2020年 | 19篇 |
2019年 | 26篇 |
2018年 | 16篇 |
2017年 | 21篇 |
2016年 | 24篇 |
2015年 | 31篇 |
2014年 | 32篇 |
2013年 | 51篇 |
2012年 | 32篇 |
2011年 | 39篇 |
2010年 | 32篇 |
2009年 | 31篇 |
2008年 | 40篇 |
2007年 | 47篇 |
2006年 | 53篇 |
2005年 | 51篇 |
2004年 | 45篇 |
2003年 | 40篇 |
2002年 | 34篇 |
2001年 | 12篇 |
2000年 | 35篇 |
1999年 | 22篇 |
1998年 | 29篇 |
1997年 | 27篇 |
1996年 | 17篇 |
1995年 | 18篇 |
1994年 | 19篇 |
1993年 | 17篇 |
1992年 | 9篇 |
1991年 | 9篇 |
1990年 | 16篇 |
1989年 | 11篇 |
1988年 | 15篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 17篇 |
1984年 | 17篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1974年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有1060条查询结果,搜索用时 31 毫秒
1.
Kenji Tsuji Shinji KitamuraHirofumi Makino 《Biochemical and biophysical research communications》2014
The kidneys are exposed to hypoxic conditions during development. Hypoxia-inducible factor (HIF), an important mediator of the response to hypoxia, is believed to have an important role in development. However, the relationship between HIF and branching morphogenesis has not been elucidated clearly. 相似文献
2.
Means to increase the reproductive capacity of Crocus sativus L., in vitro, are described. Cytokinins and auxin were found to be essential for development of bud explants. Ethylene and ethaphon pretreatments inhibited leaf development but induced corm production. Microsurgery of the apical bud combined with ethylene pretreatment increased both sprouting and corm production. 相似文献
3.
Antoine Fleureau Mathieu Lacome Martin Buchheit Antoine Couturier Giuseppe Rabita 《Biology of sport / Institute of Sport》2020,37(4):351
The aim of this study was to examine the concurrent validity of the Kinexon local positioning system (LPS) in comparison with the Vicon motion capture system used as the reference. Five recreationally active men performed ten repetitions of linear sprints, medio-lateral side-to-side and handball-specific movements both in the centre and on the side of an indoor field. Validity was assessed for peak speed, peak acceleration and peak deceleration using standardised biases, Pearson coefficient of correlation (r), and standardised typical error of the estimate. With the exception of peak decelerations during specific movements in the centre and peak acceleration and deceleration during linear sprints on the side of the field, the standardised typical error of the estimate (TEE) values were all small to moderate (0.06–0.48), standardised bias ranged between 0.01 and 2.85 and Pearson coefficient values were all > 0.90 for all variables in all conditions. Peak acceleration and deceleration during linear sprints on the side of the field showed the largest TEEs and the greatest differences between the two systems. The ultra-wideband based (UWB) local positioning system had acceptable validity compared with Vicon to assess players’ movements in handball with the exception of high accelerations and decelerations during linear sprints on the side of the field. 相似文献
4.
A single treatment with lidocaine(2-Diethylamino-N-[2,6-dimethylphenyl]-acetamide) – a potent localanaesthetic(LA), caused significant and extensive inhibition of epiphyllous buddifferentiation in Kalanchoe pinnata, in a long –term irreversible manner. These effects were both concentration and treatmentduration dependent, with either variant generating similar and additiveeffects.The growth responses studied had differential sensitivity towards the applieddosage of the anaesthetic. Lidocaine also appears to influence expression oftheorganogenic potential of buds since for all inhibitory doses a significantpercentage produced shoots but not roots. 相似文献
5.
V. Selvakumar P. R. Anbudurai T. Balakumar 《In vitro cellular & developmental biology. Plant》2001,37(2):280-284
Summary A protocol for rapid in vitro propagation using nodal explants obtained from 2-yr-old, field-grown medicinal plants of Plumbago zeylanica L. belonging to the family Plumbaginaceae is described. High frequency bud break and fast development of shoots were induced
on Murashige and Skoog's basal medium supplemented with 27.2 μM adenine sulfate +2.46 μM indole-3-butyric acid (IBA). Induction of rooting was achieved by transferring the shoots to the same basal medium containing
4.92 μM IBA. Using our protocol from one twig of P. zeylanica (eight responsive nodes per explant shoot) within a period of 5 mo., eight plantlets could be raised. After a hardening period
of 4 wk, there was a 90% transplantation success in the field compared to the 60–65% survival of plantlets recorded in the
experiments of previous workers. The plantlets derived through in vitro propagation mimic the growth and morphological characteristics of the donor plants. 相似文献
6.
F. Fontaine E. Kiefer C. Clément M. Burrus J. L. Druelle 《Trees - Structure and Function》1999,14(2):83-90
In the present work, we described the fate of proventitious epicormic buds on the trunks of 40-year-old Quercus petraea trees and in parallel the vascular trace they produced in the wood. Our results show that small and large individual epicormic
buds can survive as buds for 40 years and that both are composed of a terminal meristem and scales. Meristematic areas are
detected in the scale axils of small buds; in addition to these meristems the large buds also have secondary bud primordia.
The small buds are connected to the pith of the main stem by a unique trace, whereas the large buds are connected by one or
multiple traces. A single trace might imply that the whole bud is still alive and multiple traces might indicate that the
terminal meristem has died. In the latter case, each trace is connected to a secondary bud of the large bud. The buds found
in a cluster are composed of a terminal meristem and scales with axillary meristems in the scale axils. A cluster is connected
to the pith of a stem either by a unique trace when it seems to be the result of partial abscission of an epicormic shoot
or multiple traces when it might have originated from an epicormic bud in which the terminal meristem has died. Whatever the
type of the bud, the vascular trace in the bark is composed of a cambium, secondary xylem and parenchyma cells and the trace
present in the wood had parenchyma cells with vestiges of secondary xylem. Each year, the vascular trace should be produced
in the bark by the cambium of the tree but not by the bud itself. On 40-year-old Q. petraea, we observed a proliferation of epicormic buds and in parallel a multiplication of the number of vascular traces in the trunk,
but the knots caused by the traces of epicormic buds in the wood, either as individuals or in clusters, are minor since their
colours are only slightly darker than those of woody rays and they are less than 2 mm in diameter. The knots will appear when
epicormic buds develop into shoots.
Received: 30 March 1999 / Accepted: 09 June 1999 相似文献
7.
8.
Length of elementary shoots and the number of metamers in them have been compared in a number of ligneous plants. The shoot length varies to a greater extent than the number of metamers. The number of metamers with bud scales is the most invariable and species-specific. This indicates relative independence of the intrabud stage of the shoot development. 相似文献
9.
10.
The capacity of preformation and neoformation and the structure of winter buds are vegetative attributes that may vary between plant species and according to ontogenetic stages of the same species. The present study describes and evaluates these features for the four tree species of Proteaceae occurring in Patagonia. In particular, it analyzes the structure and development of the distal buds of the trunk and the preformed or neoformed nature of the organs involved. Two of the species, Embothrium coccineum and Lomatia hirsuta, have scaly buds, in which primordia of green leaves are covered by cataphylls. The shoots of both species may include neoformed organs, more frequently so in juvenile trees. Lomatia ferruginea and Gevuina avellana have naked buds with a low number of primordia; in juvenile and adult trees of both species trunk shoots are entirely preformed. The structure of buds and shoots suggests two different growth modalities of the axes, which would be related to ecological breadth (narrower in the species with naked buds than in those with scaly buds) and distribution area of these species. The considerable morphological differences between the two Lomatia species studied raise the question whether they ought to be included in the same genus. 相似文献