全文获取类型
收费全文 | 1749篇 |
免费 | 170篇 |
国内免费 | 1篇 |
专业分类
林业 | 240篇 |
农学 | 77篇 |
基础科学 | 8篇 |
322篇 | |
综合类 | 125篇 |
农作物 | 56篇 |
水产渔业 | 164篇 |
畜牧兽医 | 700篇 |
园艺 | 43篇 |
植物保护 | 185篇 |
出版年
2024年 | 3篇 |
2023年 | 26篇 |
2022年 | 32篇 |
2021年 | 56篇 |
2020年 | 52篇 |
2019年 | 29篇 |
2018年 | 120篇 |
2017年 | 106篇 |
2016年 | 100篇 |
2015年 | 62篇 |
2014年 | 67篇 |
2013年 | 119篇 |
2012年 | 131篇 |
2011年 | 128篇 |
2010年 | 69篇 |
2009年 | 67篇 |
2008年 | 115篇 |
2007年 | 114篇 |
2006年 | 95篇 |
2005年 | 85篇 |
2004年 | 70篇 |
2003年 | 72篇 |
2002年 | 65篇 |
2001年 | 29篇 |
2000年 | 18篇 |
1999年 | 12篇 |
1998年 | 12篇 |
1997年 | 6篇 |
1996年 | 10篇 |
1995年 | 13篇 |
1994年 | 6篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1968年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有1920条查询结果,搜索用时 250 毫秒
181.
Kiliç N Kirkan S 《Journal of veterinary medicine. A, Physiology, pathology, clinical medicine》2004,51(7-8):363-364
An actinomycotic granuloma caused by Actinomyces viscosus is reported in a dromedary camel. Two hard, cutaneous, large granulamatous nodules were present on both sides of the postero-ventral side of the mandible exhibiting exudation and necrosis. After radical excision of the lesion, the daily treatment with penicillin-streptomycin combination was continued for 4 weeks. About 8 and 24 weeks from the initial treatment, no new nodules were noticed. 相似文献
182.
Ongör H Cetinkaya B Açik MN Karahan M Bulut H 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2004,51(1):43-45
The present study was carried out to investigate the presence of Chlamydophila abortus, the causative agent of ovine enzootic abortion, in milk samples collected from sheep flocks with and without the history of abortion in Eastern Turkey by means of immunomagnetic separation (IMS) in conjunction with the polymerase chain reaction (PCR). A total number of 201 milk samples collected from 10 flocks with abortion and four flocks without abortion were tested. In the analysis of the milk samples by IMS-PCR, correct amplification was obtained with three (1.5%) samples originating from one flock with abortion. In the digestion of PCR positive products by AluI, restriction profiles observed in all three samples were determined to be the same as C. abortus S26/3. 相似文献
183.
Bibring JP Langevin Y Mustard JF Poulet F Arvidson R Gendrin A Gondet B Mangold N Pinet P Forget F Berthé M Bibring JP Gendrin A Gomez C Gondet B Jouglet D Poulet F Soufflot A Vincendon M Combes M Drossart P Encrenaz T Fouchet T Merchiorri R Belluci G Altieri F Formisano V Capaccioni F Cerroni P Coradini A Fonti S Korablev O Kottsov V Ignatiev N Moroz V Titov D Zasova L Loiseau D Mangold N Pinet P Douté S Schmitt B Sotin C Hauber E Hoffmann H Jaumann R Keller U Arvidson R Mustard JF Duxbury T 《Science (New York, N.Y.)》2006,312(5772):400-404
Global mineralogical mapping of Mars by the Observatoire pour la Mineralogie, l'Eau, les Glaces et l'Activité (OMEGA) instrument on the European Space Agency's Mars Express spacecraft provides new information on Mars' geological and climatic history. Phyllosilicates formed by aqueous alteration very early in the planet's history (the "phyllocian" era) are found in the oldest terrains; sulfates were formed in a second era (the "theiikian" era) in an acidic environment. Beginning about 3.5 billion years ago, the last era (the "siderikian") is dominated by the formation of anhydrous ferric oxides in a slow superficial weathering, without liquid water playing a major role across the planet. 相似文献
184.
Theories about sexual selection can be traced back to Darwin in 1871. He proposed that males fertilize as many females as possible with inexpensive sperm, whereas females, with a limited supply of large eggs, select the genetically highest quality males to endow their offspring with superior capabilities. Since its proposal, problems with this narrative have continued to accumulate, and it is our view that sexual selection theory needs to be replaced. We suggest an approach that relies on the exchange of direct ecological benefits among cooperating animals without reference to genetic benefits. This approach can be expressed mathematically in a branch of game theory that pertains to bargaining and side payments. 相似文献
185.
Philippe S Barron C Robert P Devaux MF Saulnier L Guillon F 《Journal of agricultural and food chemistry》2006,54(14):5113-5119
The time course and pattern of arabinoxylan deposition in the wheat (Triticum aestivum) endosperm during grain development were studied using Raman spectroscopy. The presence of arabinoxylans (AX) is detected at the beginning of grain filling. At this stage, AX appear more substituted than at the later stages. Feruloylation of AX increases during the grain-filling stage, especially in the case of the aleurone layer. Whatever the stage of grain development, four populations of cells could be defined according to Raman arabinoxylan signatures. In the walls of the aleurone cells, AX appeared to be little substituted and highly esterified with phenolic acids. In the walls of prismatic cells, AX were found to be highly substituted and poorly esterified. Apart from aleurone and prismatic cells, the substitution degree of AX in endosperm was in the same range. Cells in the crease region were distinguished from cells in the starchy endosperm by their lower amount of esterified phenolic compounds. 相似文献
186.
Grougnet R Magiatis P Mitaku S Terzis A Tillequin F Skaltsounis AL 《Journal of agricultural and food chemistry》2006,54(20):7570-7574
A procedure, based on XAD-4 adsorption resin, which permits the obtainment of enriched polyphenolic extracts from Sesamum indicum perisperm (coat) has been developed. Chemical analysis of the obtained extracts led to the identification of 16 lignans. Among them, two new lignans, (+)-saminol and (+)-episesaminone-9-O-beta-D-sophoroside, have been isolated. Additionally, the relative stereochemistry of (-)-sesamolactol, previously reported as todolactol A epimer, has been unequivocally defined using X-ray crystallography. The structures of all new compounds were determined by spectroscopic methods, mainly by the concerted application of 1D and 2D NMR techniques (HMQC, HMBC, and NOESY) and mass spectroscopy. 相似文献
187.
188.
189.
Cam Y Cetin E Iça A Atalay O Cetin N 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2006,53(4):201-202
The objective of this study was to evaluate some coagulation parameters in hepatic coccidiosis experimentally induced with Eimeria stiedai in rabbits. Fourteen healthy New Zealand rabbits were equally divided into two groups. One group received no treatment, the other group was orally inoculated with 40 000 sporulated oocysts of E. stiedai in a 1 ml inoculum using a catheter. At day 24 after inoculation, blood samples were collected into sodium citrate-containing tubes to evaluate some coagulation parameters. Although statistically not significant, infected rabbits had prolonged prothrombin time and activated partial thromboplastin time compared with rabbits in the control group. A significant reduction (P < 0.05) was observed in the level of fibrinogen of infected rabbits compared with that of the controls. A slight decrease in thrombocyte counts of infected rabbits was not statistically significant. 相似文献
190.
Reliable detection of Coxiella burnetii shedders is a critical point for the control of the spread of this bacterium among animals and from animals to humans. Coxiella burnetii is shed by ruminants mainly by birth products (placenta, birth fluids), but may also be shed by vaginal mucus, milk, and faeces, urine and semen. However, the informative value of these types of samples to identify shedders under field conditions is unknown. Our aim was then to describe the responses obtained using a real-time PCR technique applied to milk, vaginal mucus and faeces samples taken from 242 dairy cows in commercial dairy herds known to be naturally infected with Coxiella burnetii, and to assess their putative associations. Positive results were found in all types of tested samples even in faeces. No predominant shedding route was identified. Among the shedder cows, 65.4% were detected as shedders by only one route. By contrast, cows with positive results for all three samples were scarce (less than 7%). Testing a cow based on only one type of biological sample may lead to misclassify it with regards to its shedding of Coxiella burnetii and thereby underestimate the risk of bacterial spread within a herd. 相似文献