全文获取类型
收费全文 | 507篇 |
免费 | 23篇 |
专业分类
林业 | 19篇 |
农学 | 50篇 |
基础科学 | 2篇 |
56篇 | |
综合类 | 116篇 |
农作物 | 17篇 |
水产渔业 | 12篇 |
畜牧兽医 | 220篇 |
园艺 | 5篇 |
植物保护 | 33篇 |
出版年
2023年 | 4篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 11篇 |
2017年 | 9篇 |
2016年 | 4篇 |
2014年 | 7篇 |
2013年 | 26篇 |
2012年 | 11篇 |
2011年 | 20篇 |
2010年 | 11篇 |
2009年 | 9篇 |
2008年 | 16篇 |
2007年 | 16篇 |
2006年 | 22篇 |
2005年 | 23篇 |
2004年 | 16篇 |
2003年 | 10篇 |
2002年 | 18篇 |
2001年 | 15篇 |
2000年 | 14篇 |
1999年 | 10篇 |
1998年 | 4篇 |
1996年 | 5篇 |
1995年 | 17篇 |
1994年 | 9篇 |
1993年 | 6篇 |
1992年 | 13篇 |
1991年 | 11篇 |
1990年 | 12篇 |
1989年 | 10篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1971年 | 4篇 |
1907年 | 4篇 |
1905年 | 5篇 |
1904年 | 5篇 |
1903年 | 4篇 |
1902年 | 3篇 |
1900年 | 3篇 |
1897年 | 4篇 |
1896年 | 6篇 |
1884年 | 6篇 |
排序方式: 共有530条查询结果,搜索用时 15 毫秒
111.
Identification of a target‐site mutation conferring resistance to triazine herbicides in oriental mustard (Sisymbrium orientale L.) from Australia 下载免费PDF全文
Hue T. Dang Jenna M. Malone Peter Boutsalis Gurjeet Gill Christopher Preston 《Weed Biology and Management》2017,17(4):153-160
In southern Australia, oriental mustard (Sisymbrium orientale) has been controlled successfully by triazine herbicides for several decades. The screening of 40 populations that were collected from the southern grain belt of Australia during 2010 and 2013 for resistance to six different herbicides (glyphosate, diflufenican, imazamox, chlorsulfuron, atrazine and 2,4‐dichlorophenoxyacetic acid) identified two oriental mustard populations as highly resistant to atrazine. Compared to the known oriental mustard‐susceptible populations (S1 and S2), these two resistant populations (P17 and P18) from near Horsham, Victoria, Australia, were 311‐ and 315‐fold resistant to atrazine, as determined by a comparison of the LD50 values. However, there was no resistance to diuron detected in these populations. Sequencing of the chloroplast psbA gene identified a missense mutation of serine 264 to glycine in both herbicide‐resistant oriental mustard populations, which is known to confer high‐level atrazine resistance in other species. 相似文献
112.
A wild Peregrine Falcon (Falco peregrinus) was presented with extensive bilateral fluorescein positive corneal damage. Local therapy and bilateral tarsorrhaphies resulted in slow improvement over 5 weeks. When bilateral 360 degree conjunctival flaps were used subsequently, healing proceeded more rapidly over the next 8 weeks. Although bulbar conjunctival flaps have been reported as difficult in birds due to their small size and relatively immobile bulbar conjunctiva, 360 degree conjunctival flaps made from palpebral rather than bulbar conjunctiva were found to be technically feasible in a larger bird species such as the Peregrine Falcon. 相似文献
113.
Effects of supplemental vitamin D3 on feed intake, carcass characteristics, tenderness, and muscle properties of beef steers. 总被引:4,自引:0,他引:4
K Karges J C Brooks D R Gill J E Breazile F N Owens J B Morgan 《Journal of animal science》2001,79(11):2844-2850
Research was conducted to determine the effects of supplemental dietary vitamin D3 on DMI, carcass traits, Warner Bratzler shear (WBS) force, calpastatin activity, plasma minerals, pH (0, 3, 12, and 24 h after slaughter), water-holding capacity (WHC), and sensory characteristics of three muscles. Pre-slaughter vitamin D3 treatments included no supplemental vitamin D3, 6 x 106 IU (MIU) of vitamin D3 for 4 d, or 6 MIU of vitamin D3 for 6 d. Cattle were slaughtered and carcasses were chilled for 48 h before removal of steaks from the longissimus, gluteus medius, and biceps femoris muscles. Steaks were aged at 2 degrees C for 7, 14, or 21 d before cooking to a final internal temperature of 70 degrees C for WBS and sensory panel analysis. Dry matter intake was lower for steers supplemented with vitamin D3 for 4 or 6 d. Live and carcass weights were lower (P < 0.05) in steers supplemented with vitamin D3. Supplementing 6 MIU/6 d of vitamin D3 decreased (P < 0.05) WBS values of gluteus steaks (pooled over aging times). Longissimus steaks from steers supplemented with vitamin D3 for 6 d had lower (P < 0.05) WBS force values than these steaks from control steers or steers fed vitamin D3 for 4 d at 7 d postmortem. Biceps femoris steaks from steers receiving vitamin D3 for 4 d had higher WBS values than steaks from control steers at 14 and 21 d postmortem. Feeding vitamin D3 at 6 MIU for 6 d decreased (P < 0.05) the percentage of steaks that had WBS values > or = 3.86 kg for all steaks. Feeding vitamin D3 had no effect on palatability traits evaluated by trained panelists. Blood Ca concentrations were greater (P < 0.05) when vitamin D3 was fed and with increased vitamin D3 feeding time. Feeding vitamin D3 for 6 d (vs 4 d) delayed pH decline for all muscle types after 0, 3, and 12 h postmortem. Water-holding capacity was increased (P > 0.02) after 0 h, 24 h, and 21 d postmortem when vitamin D3 was fed and was greater at 0 and 24 h if vitamin D3 was fed for 6 d rather than 4 d. These data suggest that supplementing 6 MIU of vitamin D3 will decrease DMI and improve beef tenderness through increased blood plasma Ca concentrations and WHC. 相似文献
114.
Infection of six guinea pigs with up to 100 third-stage larvae of Elaphostrongylus cervi produced clinical signs of severe weight loss and ataxia or death in five. These signs occurred approximately eighty days after the larvae had been given per os. Single female E. cervi sub-adults were recovered from four affected animals and both a male and female E. cervi from one animal. Individual worms were found at the base of the brain against the internal surface of the dura mater. Histological and haematological parameters differed significantly between infected and control animals. 相似文献
115.
H R Spires A Olmsted L L Berger J P Fontenot D R Gill J G Riley M I Wray R A Zinn 《Journal of animal science》1990,68(10):3382-3391
One thousand twenty steers and heifers were used in six feeding trials to examine the influence of laidlomycin propionate on feedlot performance and to determine the most efficacious dietary concentrations of that ionophore. Cattle were fed diets ranging in energy content from 1.08 to 1.49 Mcal NEg/kg of DM. Laidlomycin propionate improved rate of gain and feed conversion in both steers and heifers. Improvements in performance were not evident when laidlomycin propionate was fed at only 3 mg/kg. However, both average daily gain and feed conversion were improved by laidlomycin propionate within the range of 6 to 12 mg/kg of DM (P less than .001). Feed consumption was not substantially affected by inclusion of laidlomycin propionate in the diet. Improvements in ADG and feed conversion were greater on lower-energy diets than on higher-energy diets, but both these performance characteristics were improved regardless of the type of diet fed. Average daily gain was maximized with laidlomycin propionate at 6 mg/kg, whereas improvements in feed conversion were sustained through 12 mg/kg. Carcasses of cattle fed diets containing 6 to 12 mg/kg of laidlomycin propionate weighed 7.3 kg more (P less than .001) than carcasses of cattle fed the control diets. Yield grade and quality grade were not affected by laidlomycin propionate (P greater than .05). 相似文献
116.
Katzman S Kern AD Bejerano G Fewell G Fulton L Wilson RK Salama SR Haussler D 《Science (New York, N.Y.)》2007,317(5840):915
Ultraconserved elements in the human genome are defined as stretches of at least 200 base pairs of DNA that match identically with corresponding regions in the mouse and rat genomes. Most ultraconserved elements are noncoding and have been evolutionarily conserved since mammal and bird ancestors diverged over 300 million years ago. The reason for this extreme conservation remains a mystery. It has been speculated that they are mutational cold spots or regions where every site is under weak but still detectable negative selection. However, analysis of the derived allele frequency spectrum shows that these regions are in fact under negative selection that is much stronger than that in protein coding genes. 相似文献
117.
Experimental exposure to Cr(VI) induced anomalies in the peripheral blood and tissues of a freshwater fish, Barbus conchonius. Clinical findings in the blood corpuscles included swelling of erythrocytes, numerous circulating polychromatophils, and vacuolation of large lymphocytes during acute exposure. Poikilocytosis, severe cytoplasmic vacuolation and deterioration of cytoplasmic membrane in erythrocytes occurred following chronic exposure. Significant polycythemia with collateral rise in Hb and Hct were manifest in the acutely intoxicated fish. By contrast, chronic exposure caused marked erythropenia and an accompanying reduction in Hb and Hct values. Leucocyte subpopulations showed an initial rise and then a fall in the thrombocytes together with a significant lymphocytosis, neutropenia, and basophilia. Pathological changes were observed in the gills, kidneys, and liver of Cr-exposed fish. 相似文献
118.
119.
D.R. Coventry R.S. PoswalS.C. Gill R.S. ChhokarV. Kumar R.K. SharmaA. Kumar A. MehtaS.G.L. Kleemann J.A. Cummins 《Field Crops Research》2011,123(3):234-240
This article reports on field experiments with 4 different rotations that are commonly used throughout Haryana in NW India (rice-wheat, cotton-wheat, pearl millet-wheat, cluster bean-wheat), where we assess wheat yield and chapatti quality measures with different crop establishment methods and input of micronutrients. In a series of experiments conducted on farmers’ fields in 2007-2008 and 2008-2009 winter seasons, the addition of micronutrients and sulphur to wheat crops was used alongside the use of a common farmer practice, the use of farmyard manure (FM) and best practice inputs of N-fertilizer (150 kg N ha−1), P-fertilizer (26 kg P ha−1) and K-fertilizer (33 kg K ha−1). The application of FM with the recommended NPK treatment produced 9-13% more grain yield in the rice-wheat rotation when compared with the recommended NPK only treatment. Given that the farm sites used here had low levels of soil P, this may suggest that the recommended rate of 26 kg P ha−1 for the rice-wheat rotation is too low. The addition of FM did not improve any grain quality outcomes at any of the sites. There were no yield responses with S application with any of the rotations but the S input resulted in more wheat protein from all sites (average 8%). The addition of S also gave similar increases in grain hardness and the chapatti score. The inclusion of micronutrients (boron, copper, iron, zinc and manganese) with the recommended NPK treatment did not increase the grain yield at any of the sites when compared with the recommended NPK treatment, and sometimes, but not consistently, gave small responses with protein, grain hardness and chapatti score. In concurrent experiments wheat growth and chapatti quality were compared in zero till and conventionally sown systems, and with and without S fertilizer amendment. Here too there were no grain yield responses to S, and the protein, grain hardness and chapatti score were increased with S addition. Grain yields with zero till and conventional wheat were similar in the rice-wheat system and zero till sowing resulted in small increases in yield at all of the non-rice sites. The grain from the zero till treatments had higher protein (1-3%), grain hardness (3-10%) and chapatti score from all 4 rotations. Zero till has substantial adoption in the rice-wheat districts of Haryana but little farmer awareness and adoption in the areas where the other rotations are used. The data given here show that with zero tillage and an integrated practice of nutrient management farmers in Haryana can maintain grain yields of wheat whilst improving quality outcomes. 相似文献
120.
Santokh Gill Tracey Goldstein Donna Situ Tanja S. Zabka Frances M. D. Gulland Rudi W. Mueller 《Marine drugs》2010,8(5):1637-1649
Domoic acid produced by marine algae has been shown to cause acute and chronic neurologic sequelae in Californian sea lions following acute or low-dose exposure. Histological findings in affected animals included a degenerative cardiomyopathy that was hypothesized to be caused by over-excitation of the glutamate receptors (GluRs) speculated to be present in the sea lion heart. Thus tissues from five sea lions without lesions associated with domoic acid toxicity and one animal with domoic acid-induced chronic neurologic sequelae and degenerative cardiomyopathy were examined for the presence of GluRs. Immunohistochemistry localized mGluR 2/3, mGluR 5, GluR 2/3 and NMDAR 1 in structures of the conducting system and blood vessels. NMDAR 1 and GluR 2/3 were the most widespread as immunoreactivity was observed within sea lion conducting system structures. PCR analysis, cloning and subsequent sequencing of the seal lion GluRs showed only 80% homology to those from rats, but more than 95% homologous to those from dogs. The cellular distribution and expression of subtypes of GluRs in the sea lion hearts suggests that exposure to domoic acid may induce cardiac damage and functional disturbances. 相似文献