全文获取类型
收费全文 | 504篇 |
免费 | 28篇 |
国内免费 | 1篇 |
专业分类
林业 | 36篇 |
农学 | 52篇 |
基础科学 | 3篇 |
112篇 | |
综合类 | 57篇 |
农作物 | 19篇 |
水产渔业 | 14篇 |
畜牧兽医 | 194篇 |
园艺 | 12篇 |
植物保护 | 34篇 |
出版年
2022年 | 5篇 |
2021年 | 11篇 |
2020年 | 8篇 |
2019年 | 11篇 |
2018年 | 14篇 |
2017年 | 9篇 |
2016年 | 7篇 |
2015年 | 10篇 |
2014年 | 7篇 |
2013年 | 16篇 |
2012年 | 30篇 |
2011年 | 32篇 |
2010年 | 24篇 |
2009年 | 19篇 |
2008年 | 28篇 |
2007年 | 30篇 |
2006年 | 32篇 |
2005年 | 21篇 |
2004年 | 36篇 |
2003年 | 26篇 |
2002年 | 28篇 |
2001年 | 4篇 |
2000年 | 5篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 8篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 8篇 |
1992年 | 7篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1978年 | 4篇 |
1976年 | 3篇 |
1967年 | 2篇 |
1962年 | 1篇 |
1958年 | 1篇 |
1955年 | 1篇 |
1939年 | 1篇 |
排序方式: 共有533条查询结果,搜索用时 0 毫秒
21.
OBJECTIVE: To evaluate single and double layer end-to-end anastomosis in equine jejunum. STUDY DESIGN: Experimental in vitro study. ANIMALS: Mid-jejunal sections from 12 adult horses without gastrointestinal disease. METHODS: Jejunal end-to-end anastomoses were performed by a continuous Lembert pattern or a simple continuous pattern oversewn with a Cushing pattern. Jejunal segments were distended with fluid at 1 L/min, and intraluminal pressure at failure, and mode of failure were recorded. Bursting pressure and bursting wall tension were calculated. Anastomosis construction time and degree of luminal reduction were recorded. Results- Single layer anastomoses were constructed in less time than 2-layer anastomoses. Both anastomotic techniques resulted in luminal reduction compared with control tissue; however, the reduction was smaller with a 1-layer continuous Lembert anastomosis. No differences were noted in bursting pressure or bursting wall tension between groups. CONCLUSIONS: Anastomosis using a 1-layer continuous Lembert pattern resulted in a larger stoma, was faster to perform, and as strong as a 2-layer anastomosis. CLINICAL RELEVANCE: Use of a 1-layer continuous Lembert pattern for jejunojejunosotomy may be beneficial by decreasing anastomosis time and produce a larger stoma than a 2-layer anastomosis. 相似文献
22.
23.
Hsieh YH Ofori JA Rao Q Bridgeman CR 《Journal of agricultural and food chemistry》2007,55(16):6720-6725
Bovine plasma proteins are used as high-quality protein supplements in animal feed and as binders or colorants in food for human consumption. Religious observance, as well as recent fears of epidemic bovine spongiform encephalopathy, highlights the need for methods to detect bovine blood in processed food and animal feed for regulatory purposes, as the currently available methods are neither species-specific, blood-specific, nor valid for excessively heat-processed samples. This paper reports the development of monoclonal antibodies (MAbs) raised against bovine thermostable plasma proteins that display a unique species specificity pattern for plasma proteins. Immunoblotting revealed several thermostable antigenic proteins (10, 25, 40, and 60 kDa) in bovine plasma sterilized at 121 degrees C for 15 min. These MAbs can be employed individually or combined in immunoassays for analytical purposes and investigations of the chemical and biological properties of the thermostable plasma proteins identified here. 相似文献
24.
The feeding of ruminant proteins to ruminants is prohibited in most countries because the practice is thought to be responsible for the spread of bovine spongiform encephalopathy. However, currently available methods to detect ruminant blood products in rendered feedstuffs are inadequate because they lack species specificity, tissue specificity, and are not based on a thermostable analyte. A sandwich enzyme-linked immunosorbent assay (ELISA) was developed for this study that provides reliable and sensitive (0.05-0.5% v/v) detection of bovine blood materials in animal feed. The new sandwich ELISA employs two previously developed monoclonal antibodies (MAbs), Bb6G12 as the capture antibody and biotinylated MAb Bb3D6 as the detecting antibody, and is bovine-specific and blood-specific. The assay is based on the detection of a 60 kDa thermostable protein in bovine blood and provides a useful regulatory tool for monitoring fraudulent labeling or contamination of bovine blood in both heat-processed feedstuffs and unprocessed raw materials. Keywords: Bovine; blood; monoclonal antibody; sandwich ELISA. 相似文献
25.
Agu RC Brosnan JM Bringhurst TA Palmer GH Jack FR 《Journal of agricultural and food chemistry》2007,55(9):3702-3707
Detailed studies were carried out on the influence of corn size distribution on the values obtained for diastatic power (DP) of commercially malted barley. Malted barley was screened using a screening box, and the DP activities of the different corns retained on the different compartments of the screening box were determined. The malt samples retained on the 2.8 mm screen had the highest DP activity, whereas the small corns (相似文献
26.
Freshwater suspensions of pulp fiber in concentrations exceeding 1000 ppm at 15°C are acutely lethal to sockeye salmon fingerlings. Limited adaptation of such fish to fiber is possible but injury, at least in the short term, is irreversible. The acute lethality of various toxicants associated with industrial pulps is synergistically enhanced by the presence of fiber, and pulp storage up to 158 days at 15°C had no significant effect on the acute lethality. Highly purified fibers are less toxic in fresh than in sea water. The sensitivity to fiber of fish from two sources did not differ significantly. 相似文献
27.
Peter M. Chapman J. David Popham Jack Griffin David Leslie John Michaelson 《Water, air, and soil pollution》1987,33(3-4):295-308
This study showed that particulate (i.e., physical) toxicity was responsible for rainbow trout deaths in bioassays with two separate solid wastes. This conclusion was based on: (1) fish necropsies which indicated physical damage to gills but no evidence of chemical damage to liver or kidney, (2) chemical analyses which indicated that levels of Priority Pollutants and other target compounds were too low to cause the observed toxicity, (3) structural and chemical analyses of the waste particles which showed that these consisted of inert materials, and (4) the use of centrifugation techniques to remove most of the suspended particulate material in bioassay tanks resulting in an elimination of most of the toxicity. The particles associated with the lethal effects were approximately 5 to 10 μm in size. Regulatory testing of solid wastes must distinguish physical and chemical toxicity since disposal options can vary depending on the mode of toxicity. For instance, chemical toxicity raises concern regarding leaching through soils into groundwater, whereas if physical particles are responsible for toxicity, such leaching is not of concern. 相似文献
28.
Weel KG Boelrijk AE Burger JJ Verschueren M Gruppen H Voragen AG Smit G 《Journal of agricultural and food chemistry》2004,52(21):6564-6571
This paper describes a novel device to simulate in vivo aroma release from liquids. This artificial throat simulates the act of swallowing followed by exhalation and shows aroma release curves that are similar in shape to in vivo release profiles. Liquids are poured down a tube, and a thin liquid film remains at the inner wall of the tube. Subsequently, aroma compounds release from this film into a stream of air flowing through this tube, which is analyzed by MS-Nose analysis. The effects of air flow rate, contact time with glass surface, presence of saliva, and addition of whey protein, as well as volume, concentration, temperature, and viscosity of the liquid have been studied and compared with aroma release measurements in vivo. A high level of agreement was found. These results confirm the importance of swallowing for aroma release of liquids, as mentioned in the literature, and the usefulness of the new mimicking device. 相似文献
29.
Tusar K. Behera Jack E. Staub Snigdha Behera Isabelle Y. Delannay Jin Feng Chen 《Euphytica》2011,178(2):261-272
Cucumber (Cucumis sativus L.) is a major cucurbit vegetable species whose genetic base has been drastically reduced during its domestication. The crop’s
narrow genetic base (3–12% DNA polymorphism) has resulted from the use of limited genetic material and intense selection during
plant improvement. Recently, however, interspecific hybridization has been successful in Cucumis via mating of C. hystrix Chakr. and C. sativus, which resulted in the amphidiploid C. hytivus. We report herein a marker-assisted strategy for increasing genetic diversity in cucumber through introgression backcrossing
employing C. hytivus. The comparatively late-flowering but high-yielding, indeterminate, monoecious line WI 7012A (P1; donor parent) derived from a C. hytivus × C. sativus-derived line (long-fruited Chinese C. sativus cv. Beijingjietou) was initially crossed to the determinate, gynoecious C. sativus line WI 7023A (P2; recurrent parent 1), and then advanced backcross generation progeny (BC2) were crossed with the gynoecious indeterminate line WI 9-6A (P3; recurrent parent 2). More specifically, a single F1 individual (P1 × P2) was backcrossed to P2, and then BC progeny were crossed to P2 and P3, where marker-assisted selection (MAS) for genetic diversity (8 mapped and 16 unmapped markers; designated Sel) or no selection
(designated NSel) was applied to produce BC3P2 (Sel) and BC3P3 (Sel), and BC2P2 (NSel) and BC2P2S1 (NSel) progeny. Relative vegetative growth, number of lateral branches (LB), days to flowering (DF), yield (fruit number),
and fruit quality [as measured by length:diameter (L:D) and endocarp:total diameter (E:T) ratios] were assessed in parents
and cross-progeny. DF varied from ~20 (BC3P2Sel) to ~25 days (BC2P3Sel) among the populations examined, where progeny derived from P2 possessed the shortest DF. Differences in cumulative yield among the populations over six harvests were detected, varying
from ~8 fruits per plant in BC3P2 (Sel) to ~39 fruits per plant in BC2P3 (Sel). Although the vigorous vegetative growth of line P1 was observed in its backcross progeny, highly heterozygous and polymorphic backcross progeny derived from P3 were comparatively more vigorous and bore many high-quality fruit. Response to selection was detected for LB, DF, L:D, and
E:T, but the effectiveness of MAS depended upon the parental lines used. Data indicate that the genetic diversity of commercial
cucumber can be increased by introgression of the C. hystrix genome through backcrossing. 相似文献
30.
Zhu Z Zheng T Homer RJ Kim YK Chen NY Cohn L Hamid Q Elias JA 《Science (New York, N.Y.)》2004,304(5677):1678-1682
Chitin is a surface component of parasites and insects, and chitinases are induced in lower life forms during infections with these agents. Although chitin itself does not exist in humans, chitinases are present in the human genome. We show here that acidic mammalian chitinase (AMCase) is induced via a T helper-2 (Th2)-specific, interleukin-13 (IL-13)-mediated pathway in epithelial cells and macrophages in an aeroallergen asthma model and expressed in exaggerated quantities in human asthma. AMCase neutralization ameliorated Th2 inflammation and airway hyperresponsiveness, in part by inhibiting IL-13 pathway activation and chemokine induction. AMCase may thus be an important mediator of IL-13-induced responses in Th2-dominated disorders such as asthma. 相似文献