全文获取类型
收费全文 | 779篇 |
免费 | 42篇 |
专业分类
林业 | 9篇 |
农学 | 13篇 |
基础科学 | 3篇 |
81篇 | |
综合类 | 123篇 |
农作物 | 31篇 |
水产渔业 | 29篇 |
畜牧兽医 | 495篇 |
园艺 | 15篇 |
植物保护 | 22篇 |
出版年
2023年 | 8篇 |
2021年 | 6篇 |
2020年 | 9篇 |
2019年 | 8篇 |
2017年 | 6篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2014年 | 12篇 |
2013年 | 35篇 |
2012年 | 25篇 |
2011年 | 21篇 |
2010年 | 30篇 |
2009年 | 14篇 |
2008年 | 33篇 |
2007年 | 35篇 |
2006年 | 24篇 |
2005年 | 20篇 |
2004年 | 32篇 |
2003年 | 33篇 |
2002年 | 39篇 |
2001年 | 24篇 |
2000年 | 27篇 |
1999年 | 20篇 |
1998年 | 7篇 |
1996年 | 13篇 |
1995年 | 7篇 |
1993年 | 9篇 |
1992年 | 16篇 |
1991年 | 11篇 |
1990年 | 21篇 |
1989年 | 14篇 |
1988年 | 14篇 |
1987年 | 16篇 |
1986年 | 11篇 |
1985年 | 11篇 |
1984年 | 6篇 |
1982年 | 9篇 |
1981年 | 9篇 |
1979年 | 5篇 |
1974年 | 8篇 |
1972年 | 11篇 |
1971年 | 11篇 |
1970年 | 8篇 |
1968年 | 6篇 |
1967年 | 6篇 |
1966年 | 7篇 |
1965年 | 6篇 |
1963年 | 5篇 |
1961年 | 5篇 |
1946年 | 9篇 |
排序方式: 共有821条查询结果,搜索用时 62 毫秒
51.
B S Beale R L Goring M Schaer S A Robertson 《Journal of the American Veterinary Medical Association》1991,198(2):281-285
Modified choledochoduodenostomy and gastrojejunostomy were used successfully to treat extensive duodenal ulceration and perforation in a dog. Concomitant pyometra, simultaneously managed by ovariohysterectomy, may have predisposed the dog to stress ulceration. Choledochoduodenostomy was performed by transplantation of the entire common bile duct and associated major duodenal papilla to a more distal duodenal location. An indwelling choledochostomy tube was used to stent the anastomotic site, externally divert bile flow, and allow postoperative cholangiography. Early postoperative complications included presumed metronidazole-induced neurotoxicosis, choledochostomy tube obstruction, and pancreatitis, all of which resolved within 2 weeks. The dog was clinically normal and medication (ranitidine and sucralfate) was discontinued 35 months later. 相似文献
52.
53.
Guy R. Alexander BVSc Cert VR Katherine T. Gibson BVSc MS Diplomate ACVS Robert E. Day MBiomedEng BEng CPEng Ian D. Robertson BVSc PhD MACVSc 《Veterinary surgery : VS》2001,30(6):522-527
OBJECTIVE: To measure the effects of transection of the accessory ligament of the superficial digital flexor (SDF) muscle (superior check desmotomy) on flexor tendon and suspensory ligament (SL) strain in vitro. STUDY DESIGN: In vitro experimental biomechanical investigation. ANIMALS USED: Ten equine cadaver forelimbs. METHODS: The effects of superior check desmotomy were determined using equine cadaver forelimbs secured in a servocontrolled hydraulic testing machine. Strain sensors were used to measure strain on the superficial and deep digital flexor tendons and SL, and a goniometer was used to measure joint angles when the limb was loaded at 890 N and 3,115 N before desmotomy, and at 3,115 N after desmotomy. RESULTS: Superior check desmotomy was associated with significantly increased strains on the SDF tendon and SL, and significant alterations in the angles of the metacarpophalangeal and carpal joints. CONCLUSIONS: The superior check ligament has an important role in maintaining joint angles and load distribution in the forelimb. Lengthening of the SDF musculotendinous unit after superior check desmotomy may be associated with increased strain on the SL. CLINICAL RELEVANCE: Transection of the accessory ligament of the SDF muscle may predispose horses to SL desmitis postoperatively. 相似文献
54.
D. A. Bond G. J. Jellis G. G. Rowland J. Le Guen L. D. Robertson S. A. Khalil L. Li-Juan 《Euphytica》1993,73(1-2):151-166
Progress is being made, mainly by ICARDA but also elsewhere, in breeding for resistance to Botrytis, AScochyta, Uromyces, and Orobanche; and some lines have resistance to more than one pathogen. The strategy is to extend multiple resistance but also to seek new and durable forms of resistance. Internationally coordinated programs are needed to maintain the momentum of this work.Tolerance of abiotic stresses leads to types suited to dry or cold environments rather than broad adaptability, but in this cross-pollinated species, the more hybrid vigor expressed by a cultivar, the more it is likely to tolerate various stresses. 相似文献
55.
A. Soltani M. J. Robertson A. Rahemi-Karizaki J. Poorreza H. Zarei 《Journal of Agronomy and Crop Science》2006,192(5):379-389
Quantitative information regarding biomass accumulation and partitioning in chickpea (Cicer arietinum L.) is limited or inconclusive. The objective of this study was to obtain baseline values for extinction coefficient (KS), radiation use efficiency (RUE, g MJ?1) and biomass partitioning coefficients of chickpea crops grown under well‐watered conditions. The stability of these parameters during the crop life cycle and under different environmental and growth conditions, caused by season and sowing date and density, were also evaluated. Two field experiments, each with three sowing dates and four plant densities, were conducted during 2002–2004. Crop leaf area index, light interception and crop biomass were measured between emergence and maturity. A KS value of 0.5 was obtained. An average RUE of 1 g MJ?1 was obtained. Plant density had no effect on RUE, but some effects of temperature were detected. There was no effect of solar radiation or vapour pressure deficit on RUE when RUE values were corrected for the effect of temperature. RUE was constant during the whole crop cycle. A biphasic pattern was found for biomass partitioning between leaves and stems before first‐seed stage. At lower levels of total dry matter, 54 % of biomass produced was allocated to leaves, but at higher levels of total dry matter, i.e. under favourable and prolonged conditions for vegetative growth, this portion decreased to 28 %. During the period from first‐pod to first‐seed, 60 % of biomass produced went to stems, 27 % to pods and 13 % to leaves. During the period from first‐seed to maturity, 83 % of biomass was partitioned to pods. It was concluded that using fixed partitioning coefficients after first‐seed are not as effective as they are before this stage. Environmental conditions (temperature and solar radiation) and plant density did not affect partitioning of biomass. 相似文献
56.
57.
58.
We have induced and controlled normal aggregation of Dictyostelium discoideum amoebas by electrophoretic release of pulses of cyclic adenosine monophosphate from a microelectrode. This has yielded information about the sequence of development of aggregation competences during interphase. We believe that modifications of the technique will have wide application in investigations of other developing systems. 相似文献
59.
Guam amyotrophic lateral sclerosis-parkinsonism-dementia linked to a plant excitant neurotoxin 总被引:24,自引:0,他引:24
P S Spencer P B Nunn J Hugon A C Ludolph S M Ross D N Roy R C Robertson 《Science (New York, N.Y.)》1987,237(4814):517-522
The decline in the high incidence of amyotrophic lateral sclerosis, parkinsonism, and Alzheimer-type dementia among the Chamorro population of the western Pacific islands of Guam and Rota, coupled with the absence of demonstrable viral and hereditable factors in this disease, suggests the gradual disappearance of an environmental factor selectively associated with this culture. One candidate is seed of the neurotoxic plant Cycas circinalis L., a traditional source of food and medicine which has been used less with the Americanization of the Chamorro people after World War II. Macaques were fed the Cycas amino acid beta-N-methylamino-L-alanine, a low-potency convulsant that has excitotoxic activity in mouse brain, which is attenuated by N-methyl-D-aspartate receptor antagonists. These animals developed corticomoto-neuronal dysfunction, parkinsonian features, and behavioral anomalies, with chromatolytic and degenerative changes of motor neurons in cerebral cortex and spinal cord. In concert with existing epidemiological and animal data, these findings support the hypothesis that cycad exposure plays an important role in the etiology of the Guam disease. 相似文献
60.
Cloned viral protein vaccine for foot-and-mouth disease: responses in cattle and swine 总被引:88,自引:0,他引:88
D G Kleid D Yansura B Small D Dowbenko D M Moore M J Grubman P D McKercher D O Morgan B H Robertson H L Bachrach 《Science (New York, N.Y.)》1981,214(4525):1125-1129
A DNA sequence coding for the immunogenic capsid protein VP3 of foot-and-mouth disease virus A12, prepared from the virion RNA, was ligated to a plasmid designed to express a chimeric protein from the Escherichia coli tryptophan promoter-operator system. When Escherichia coli transformed with this plasmid was grown in tryptophan-depleted media, approximately 17 percent of the total cellular protein was found to be an insoluble and stable chimeric protein. The purified chimeric protein competed equally on a molar basis with VP3 for specific antibodies to foot-and-mouth disease virus. When inoculated into six cattle and two swine, this protein elicited high levels of neutralizing antibody and protection against challenge with foot-and-mouth disease virus. 相似文献