全文获取类型
收费全文 | 676篇 |
免费 | 45篇 |
国内免费 | 59篇 |
专业分类
林业 | 72篇 |
农学 | 45篇 |
基础科学 | 12篇 |
80篇 | |
综合类 | 88篇 |
农作物 | 62篇 |
水产渔业 | 120篇 |
畜牧兽医 | 207篇 |
园艺 | 25篇 |
植物保护 | 69篇 |
出版年
2024年 | 1篇 |
2023年 | 12篇 |
2022年 | 15篇 |
2021年 | 29篇 |
2020年 | 19篇 |
2019年 | 16篇 |
2018年 | 30篇 |
2017年 | 31篇 |
2016年 | 25篇 |
2015年 | 12篇 |
2014年 | 24篇 |
2013年 | 49篇 |
2012年 | 42篇 |
2011年 | 42篇 |
2010年 | 42篇 |
2009年 | 30篇 |
2008年 | 43篇 |
2007年 | 33篇 |
2006年 | 20篇 |
2005年 | 18篇 |
2004年 | 16篇 |
2003年 | 42篇 |
2002年 | 63篇 |
2001年 | 53篇 |
2000年 | 35篇 |
1999年 | 14篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1992年 | 1篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1982年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有780条查询结果,搜索用时 234 毫秒
21.
Ilhami Kiziro?lu Levend Turan Ali Erdo?an ?zdemir Adizel Nahit Pamuko?lu 《Anzeiger für Sch?dlingskunde》2002,37(1):99-102
Analysis of nestling food in four species of Parus and one species of Ficedula using the 'Halsringmethode' showed a high quota of adults and caterpillars of the important forest pests: Tortrix viridana, Euproctis chrysorrhoea, Diprion pini, and Lymantria dispar. These four major pest species amounted in the nestling food of Parus major to 50%, P. coeruleus to 52.6%, P. ater to 40.9%, and Ficedula hypoleuca to 30.2%. 相似文献
22.
国外土地整理实践对我国土地整理的启示 总被引:1,自引:0,他引:1
土地整理在我国起步较晚,很多理论还不成熟。采用文献参阅法,从土地整理的发展阶段、内容和特点等方面介绍了德国、俄国和荷兰等国外土地整理的基本情况,并由此得出其对我国土地整理的启示:建立健全土地整理法律政策,重视土地整理的权属调整,拓宽土地整理融资渠道,重视土地整理中的生态环境保护,积极推动土地整理公众参与和高度重视土地整理规划等。 相似文献
23.
SixBassus species were recorded for the first time in Turkey:B. calculator (Fabricius, 1798),B. cingulipes (Nees, 1814),B. conspicuus (Wesmael, 1837),B. graecus Achterberg, 1992,B. rugulosus (Needs, 1834) andB. zaykovi (Nixon, 1986). By adding these new records, the number ofBassus species in Turkey has been raısed from seven to 13. Distribution and known hosts are given. 相似文献
24.
The development time, survivorship and reproduction ofTuberolachnus salignus (Gmelin) (Hemiptera: Aphididae) [Lachninae, Lachnini] were studied onSalix babylonica (weeping willow) andSalix matsudana (corkscrew willow) at five constant temperatures (17.5, 20, 22.5, 25 and 27.5°C). The development time of immature stages
ofT. salignus ranged from 14.56 days at 17.5°C to 12.50 days at 25°C onS. babylonica, and 16.47 days at 20°C to 12.28 days at 25°C onS. matsudana. The total survivorship of immature stages ofT. salignus varied from 28% to 85% at 22.5 and 17.5°C, respectively, onS. babylonica, and from 13% to 63%, respectively, at 17.5 and 25°C onS. matsudana. The greatest intrinsic rate of increase occurred at 25°C onS. babylonica (0.2691) and also onS. matsudana (0.2607). The mean generation time of the aphid population ranged from 14.15 days at 25°C to 16.24 days at 17.5°C onS. babylonica, and from 14.33°C days at 25°C to 19.86 days at 20°C onS. matsudana. The optimal temperature forS. babylonica growth, development time, reproduction and percent survival was 25°C. 相似文献
25.
The Eucalyptus gall waspOphelimus maskelli (Ashmead) (Hymenoptera: Chalcidoidea: Eulophidae: Ophelimini) and its introduced parasitoidClosterocerus chamaeleon (Hymenoptera: Chalcidoidea: Eulophidae: Entedoninae) are recorded for the first time in the Mediterranean and Aegean Regions
of Turkey. Some morphological characters of adult and larva ofO. maskelli and larva ofC. chamaeleon are described and illustrated. Distributions of the two wasps collected in Turkey are given. Results indicate that the biological
control agent,C. chamaeleon, has spread over 1,300 km in the 16 months since its initial release. 相似文献
26.
In this study, the genetic relatedness of 22 low chill requiring walnut genotypes adapted to the south east Mediterranean region of Turkey was analysed by amplified fragment length polymorphism (AFLP) markers. Relatively low level of genetic variation was detected among the genotypes examined by five AFLP primer combinations, suggesting that these walnut genotypes selected predominantly for their low chill requirement have relatively narrow genetic base. In addition, the geographical proximity of the genotypes analysed was not correlated with their level of genetic relatedness. These results have implications for walnut breeding and conservation. 相似文献
27.
Menşure Özgüven Bilge Şener Ilkay Orhan Nazım Şekeroğlu Muzaffer Kirpik Murat Kartal Ipek Peşin Zülküf Kaya 《Industrial Crops and Products》2008,27(1):60-64
Artemisia annua L. is an aromatic-antibacterial herb that destroys malarial parasites, lowers fevers and checks bleeding, and of which the secondary compound of interest is artemisinin. The objective of the present study was to determine yield, yield components and artemisinin content of A. annua L. grown under four nitrogen applications (0, 40, 80 and 120 kg ha−1) in the Çukurova region of Turkey in 2004 and 2005. Field trials were conducted at Çukurova University, Agricultural Faculty Field Crops Department. In the study, plant height, number of branches, fresh herbage yield, dry herbage yield, fresh leaf yield, dry leaf yield, essential oil content and artemisinin content (by high performance liquid chromatography, HPLC) were examined. By analysis of variance, nitrogen doses had no any statistical effect on the traits investigated except for artemisinin content. Artemisinin content of the dried leaves were significantly affected by nitrogen applications, which varied from 6.32 to 27.50 mg 100 g−1. Contents were from 120 and 80 kg ha−1 nitrogen for the years of 2004 and 2005, respectively. 相似文献
28.
29.
Yusuf Bozkurt Fatih Öğretmen Uğur Erçin Ümmügülsüm Yιldιz 《Aquaculture Research》2008,39(15):1666-1672
In this research, the mineral and organic composition of the seminal plasma, physical spermatological parameters and their physiological relationships were investigated in grass carp (Ctenopharyngodon idella). The seminal plasma contained 98.14±5.23 mM L?1 (Na+), 380.85±25.95 mM L?1 (K+), 30.25±4.96 mg dL?1 (Ca2+), 19.16±1.70 mEq L?1 (Mg2+), 1.36±0.11 mg dL?1 glucose, 0.37±0.08 g dL?1 total protein, 12.02±1.18 mg dL?1 cholesterol, 14.85±1.50 mg dL?1 triglyceride and 43.5±9.56 mg dL?1 urea. The following spermatological parameters were found: sperm volume 14.44±1.16 mL, sperm motility 80.60±1.55%, movement duration 67.68±4.32 s, density 15.43±0.72 × 109 mL?1, total density 337.43+45.86 × 109 and pH 7.24±0.17. The Na+ and Ca2+ ions correlated negatively with spermatozoa motility (r=?0.453, P>0.05 and r=?0.192, P>0.05) respectively. The K+ ion correlated positively with spermatozoa motility (r=0.545, P>0.05). But a statistically significant correlation was not observed between sperm motility and seminal plasma parameters. The following correlations were observed between mineral and organic components. The Mg2+ was positively correlated with glucose and cholesterol (r=0.692, P<0.05 and r=0.680, P<0.05) respectively. A highly significant positive relationship was also found between Mg2+ and total protein (r=0.837, P<0.01). On the other hand, a significantly negative relationship was found between Ca2+ and triglyceride (r=?0.639, P<0.05). These parameters should be considered when developing procedures for either artificial fertilization or for cryopreservation of grass carp sperm. 相似文献
30.
Orhan Tufan Eroldoan O. Tabozan S. Tabakolu 《Journal of the World Aquaculture Society》2008,39(2):267-274
The effect of restricted feeding on growth, feed efficiency, and body composition was studied in juveniles of gilthead sea bream, Sparus aurata. Juveniles (6.4 g) were stocked into 12 tanks at a density of 16 fish per tank. Four different feeding schedules were tested on triplicate groups of juvenile fish: (1) control fed for 48 d without deprivation, (2) starvation for 1 d and then refed for 2 d (S1), (3) 50% satiation for 2 d and then refed to apparent satiation for 2 d (R2), and (4) 50% satiation for 6 d and then refed to apparent satiation for another 6 d (R6). Results indicated that all fish subjected to cycled restricted feeding regimes were unable to achieve catching up with control group. The specific growth rate of fish in the control was significantly higher than those in S1, R2, and R6, which were not significantly different from each other. Protein efficiency and protein productive value were significantly higher in R2 compared to control, S1, and R6. Fish in R2 had lowest feed conversion ratio (1.12) compared to the control (1.17). Body protein composition in R6 was less than that of the control, S1, and R2, while moisture, lipid, and ash content were not significantly different compared to the control. 相似文献