全文获取类型
收费全文 | 841篇 |
免费 | 48篇 |
国内免费 | 2篇 |
专业分类
林业 | 63篇 |
农学 | 34篇 |
基础科学 | 2篇 |
165篇 | |
综合类 | 40篇 |
农作物 | 68篇 |
水产渔业 | 81篇 |
畜牧兽医 | 357篇 |
园艺 | 20篇 |
植物保护 | 61篇 |
出版年
2024年 | 1篇 |
2023年 | 9篇 |
2022年 | 20篇 |
2021年 | 48篇 |
2020年 | 52篇 |
2019年 | 54篇 |
2018年 | 40篇 |
2017年 | 29篇 |
2016年 | 32篇 |
2015年 | 38篇 |
2014年 | 36篇 |
2013年 | 51篇 |
2012年 | 70篇 |
2011年 | 73篇 |
2010年 | 35篇 |
2009年 | 27篇 |
2008年 | 53篇 |
2007年 | 39篇 |
2006年 | 36篇 |
2005年 | 39篇 |
2004年 | 26篇 |
2003年 | 20篇 |
2002年 | 23篇 |
2001年 | 7篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1967年 | 1篇 |
排序方式: 共有891条查询结果,搜索用时 0 毫秒
91.
de Vasconcellos Abdon AP Coelho de Souza G Noronha Coelho de Souza L Prado Vasconcelos R Araújo Castro C Moreira Guedes M Pereira Lima RC de Azevedo Moreira R de Oliveira Monteiro-Moreira AC Rolim Campos A 《Fitoterapia》2012,83(3):604-608
The present study was designed to verify whether frutalin (FTL) affords gastroprotection against the ethanol-induced gastric damage and to examine the underlying mechanism(s). Gastric damage was induced by intragastric administration of 0.2 ml of ethanol (96%). Mice in groups were pretreated with FTL (0.25, 0.5 and 1 mg/kg; i.p.), cimetidine (100 mg/kg; p.o.), or vehicle (0.9% of NaCl, 10 mL/kg; p.o.), 30 min before ethanol administration. They were sacrificed 30 min later, the stomachs excised, and the mucosal lesion area (mm2) measured by planimetry. Gastroprotection was assessed in relation to inhibition of gastric lesion area. To study the gastroprotective mechanism(s), its relations to capsaicin-sensitive fibers, endogenous prostaglandins, nitric oxide, sulphydryls, ATP-sensitive potassium channels, adrenoceptors, opioid receptors and calcium channels were analyzed. Treatments effects on ethanol-associated oxidative stress markers GSH and MDA were measured in gastric tissue. FTL afforded a dose-unrelated gastroprotection against the ethanol damage. However, it failed to prevent the ethanol-induced changes in the levels of GSH and MDA. It was observed that the gastroprotection by FTL was greatly reduced in animals pretreated with capsazepine, indomethacin, L-NAME or glibenclamide. Considering the results, it is suggested that the FTL could probably be a good therapeutic agent for the development of new medicine for the treatment of gastric ulcer. 相似文献
92.
Ana Vasques Paula Maia Mariana Pedro Concei??o Santos V. Ramón Vallejo J. Jacob Keizer 《Annals of Forest Science》2012,69(4):499-507
? Context
Maritime Pine forests cover important mountain areas in Portugal and are known to be a particularly fire-prone forest type. Understory composition plays an important role in maintaining biodiversity and ecosystem services after recurrent wildfires.? Aims
This study aims to improve the knowledge on the germination ecology of understory species of Maritime Pine forests, focusing on the importance of seed provenance, including in relation to germination enhancement by heating.? Methods
The selected species were Cistus ladanifer L., Erica australis L., Erica umbellata L., Pterospartum tridentatum L. (Willk), and Genista triacanthos Brot. Seeds were collected from two or three distant populations. Besides a control treatment, two heating regimes were applied, i.e., 100°C during 5?min and 80°C during 30?min.? Results
Heating treatments significantly enhanced germination in four out of the five species. Differences between provenances were most evident for C. ladanifer and E. australis, especially following the heating treatments. Overall, the seeds from the southern provenances germinated better and, at the same time, were smaller.? Conclusion
The present results confirmed that seed provenance should not be ignored as a key factor in germination ecology, so that further work is needed to untangle the roles of environmental and genetic factors in the observed differences between provenances. 相似文献93.
The expansion of tree species within a grassland-woodland matrix relies heavily on an abundant seed crop, which may be affected by many factors; among these, browsing by livestock has gone largely ignored. Here we explore how seed production is affected by tree size, grazing by large domestic herbivores and interannual climate fluctuations in a small-sized tree (Polylepis australis, Rosaceae), which dominates the remnant forests in the high mountains of central Argentina. Seed number and seed mass per tree were quantified in 100 different-sized trees located in areas with and without livestock. Using seed traps we also determined seed rain variation in 15 plots between 2005 and 2008. The estimated number of seeds per tree ranged from 0 to 224,000 and increased with tree height (power relation); for trees smaller than 354 cm in height, seed production was lower in areas with livestock and higher in areas without livestock. Mass per seed increased with tree height, with no significant livestock effect. The largest seed rain was recorded in 2008, probably due to growth of seed trees and not in response to climate. To promote seed production and forest expansion, livestock should be excluded from areas with small trees, such as forest edges. 相似文献
94.
Abstract Embryogenic callus was obtained from immature regions of the leaf of Digitaria eriantha when grown in the dark on a MS medium supplemented with 1,0 or 2,0mg/dm3, 2,4‐D and 3–9 % sucrose. Plantlet regeneration occurred when the calli were transferred to MS medium containing 0,1 mg/dm3, 2,4‐D and 7–8 % sucrose, and placed under 16 hour photoperiod. The regenerated plantlets were successfully planted out into a mixture of sand and potting soil. 相似文献
95.
96.
Michel Anderson Almeida Colmanetti Allan Lopes Bacha Pedro Luis da Costa Aguiar Alves Rinaldo Cesar de Paula 《林业研究》2019,(2):537-543
In silvopasture system, the coexistence of eucalyptus seedlings with other species may result in growth reduction, especially during eucalyptus early development.Therefore, studies elucidating how forage species affect the eucalyptus growth can provide important information for their rational management aiming to obtain the maximum gain of the system. The aim of this work was to evaluate the effect of increasing densities of Urochloa brizantha cv.Marandu in the early development of Eucalyptus urograndis. An experiment was conducted in 20 L pots, in an open and semi-controlled area, during 90 days after planting of eucalyptus. A completely randomized design with four replications was used, in a 6 9 7 factorial system, meaning six evaluation periods and seven densities of U. brizantha: 0(control), 22, 33, 44, 67, 89 and111 plants m-2. Fortnightly, eucalyptus height, stem diameter and chlorophyll fluorescence(Fv/Fm) were evaluated. At the end of experimental period, the net assimilation rate, stomatal conductance and transpiration rate of eucalyptus plants were determined, in addition to the dry matter of eucalyptus(leaves and stem) and U. brizantha (leaves). In coexistence with 111 plants m-2, eucalyptus had reduction of 63.9% on total dry matter and 72.7% on leaf area, compared to the control. From the density of22 plants m-2, U. brizantha negatively interfere significantly the growth of E. urograndis. Up to 8 plants m-2 there are no reductions greater than 5% in eucalyptus height and stem diameter. 相似文献
97.
de Castro Ana Paula Ribeiro Barcelos da Cunha Diogo Thimoteo Antunes Adriane Elisabete Costa Corona Ligiana Pires Bezerra Rosângela Maria Neves 《Plant foods for human nutrition (Dordrecht, Netherlands)》2019,74(2):232-234
Plant Foods for Human Nutrition - Obesity is an important public health concern and is directly related with chronic noncommunicable diseases that affect the health of millions of people around the... 相似文献
98.
99.
100.