全文获取类型
收费全文 | 292633篇 |
免费 | 16429篇 |
国内免费 | 681篇 |
专业分类
林业 | 24231篇 |
农学 | 14159篇 |
基础科学 | 3002篇 |
45523篇 | |
综合类 | 34815篇 |
农作物 | 17365篇 |
水产渔业 | 17527篇 |
畜牧兽医 | 121411篇 |
园艺 | 6491篇 |
植物保护 | 25219篇 |
出版年
2020年 | 2944篇 |
2019年 | 3734篇 |
2018年 | 4149篇 |
2017年 | 4558篇 |
2016年 | 4946篇 |
2015年 | 4427篇 |
2014年 | 5827篇 |
2013年 | 16530篇 |
2012年 | 7363篇 |
2011年 | 9525篇 |
2010年 | 7725篇 |
2009年 | 8194篇 |
2008年 | 8849篇 |
2007年 | 7963篇 |
2006年 | 8607篇 |
2005年 | 7822篇 |
2004年 | 7633篇 |
2003年 | 7322篇 |
2002年 | 6834篇 |
2001年 | 7522篇 |
2000年 | 7157篇 |
1999年 | 6477篇 |
1998年 | 4316篇 |
1997年 | 4353篇 |
1996年 | 4077篇 |
1995年 | 4711篇 |
1994年 | 4154篇 |
1993年 | 3832篇 |
1992年 | 5291篇 |
1991年 | 5520篇 |
1990年 | 5313篇 |
1989年 | 5271篇 |
1988年 | 4781篇 |
1987年 | 4842篇 |
1986年 | 4864篇 |
1985年 | 4999篇 |
1984年 | 4530篇 |
1983年 | 4181篇 |
1982年 | 3311篇 |
1981年 | 3162篇 |
1980年 | 3124篇 |
1979年 | 3962篇 |
1978年 | 3486篇 |
1977年 | 3163篇 |
1976年 | 2860篇 |
1975年 | 2787篇 |
1974年 | 3309篇 |
1973年 | 3308篇 |
1972年 | 3050篇 |
1971年 | 2861篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
921.
Christiane Stehmann Maarten A. De Waard 《European journal of plant pathology / European Foundation for Plant Pathology》1996,102(2):171-180
Sensitivity of field isolates (121) ofBotrytis cinerea from France (1992), Germany (1979–1992), Israel (1990) and the Netherlands (1970–1989) to the triazoles tebuconazole and triadimenol, the benzimidazole benomyl and the dicarboximide vinclozolin were tested in radial growth experiments. Resistance to benomyl (in 21 to 100% of isolates tested) and vinclozolin (in 25 to 71% of isolates tested) was common in most countries. EC50s (concentrations of fungicides inhibiting radial mycelial growth ofB. cinerea on B5-agar by 50%) for tebuconazole and triadimenol ranged between 0.01–1.64 and 0.4–32.6g ml–1, respectively, and were log-normally distributed. The variation factor (ratio between EC50s of the least and most sensitive isolate tested) amounts 164 and 82 for tebuconazole and triadimenol, respectively. These values are comparable to those for azole fungicides applied in control of other pathogens. Hence, variation in sensitivity to triazoles can probably not explain limited field performance of triazoles towardsB. cinerea. Isolates from south west Germany (1992) were significantly less sensitive to tebuconazole than isolates collected earlier in Germany, Israel and the Netherlands. Such less sensitive populations may contribute to the limited field performance of DMI fungicides towardsB. cinerea. The sensitivity of isolates from south west Germany to tebuconazole was similar to that of DMI-resistant mutants generated in the laboratory. These mutants displayed stable resistance with Q-values (ratio between EC50 of resistant mutant and wild type isolate) between 5 and 20. Sensitivity of field isolates and laboratory mutants to tebuconazole and triadimenol was correlated. 相似文献
922.
P. D. de Jong 《European journal of plant pathology / European Foundation for Plant Pathology》1996,102(3):293-295
Based on a simple model, the possible effects of certification of planting material on the occurrence of leek rust in a region can be derived from information on the proportion of infected fields (v) and the proportion of newly planted fields with infected planting material (i) in that region. Ifv i, certification of planting material will be highly effective. 相似文献
923.
K. Tagata S. Yokoyama T. Ginbo M. Honda T. Okimura M. Odakura M. Nomura S. Yamamoto 《Veterinary research communications》1996,20(1):21-30
A capillary reversed passive latex agglutination test (capillary RPLA) was developed which allows quantification of serum C-reactive protein (CRP) within approximately 15 min. The logarithmic regression line (calibration curve) obtained after measuring each CRP concentration three times in twofold dilutions of a standard canine serum containing 222 g/ml of CRP was y=6.394+0.030x (r=0.995). Capillary RPLA permitted quantification of CRP in the range 6.9–222 g/ml. The coefficients of variation ranged from 10.28% to 12.40%. The recovery rates (percentage recovery) of CRP by capillary RPLA were within the range 87% to 106%. On measuring the CRP concentrations in sera from 78 dogs by capillary RPLA, single radial immunodiffusion (SRID) and enzyme-linked immunosorbent assay (ELISA), close correlations were demonstrated between SRID and capillary RPLA (y=7.250+1.109x, r=0.978), between SRID and ELISA (y=3.042+1.059x, r=0.967), and between capillary RPLA and ELISA (y=1.778+0.929x, r=0.962). Capillary RPLA may be considered useful as a routine biochemical technique for measurement of serum CRP concentration in the dog.Abbreviations CRP
C-reactive protein
- ELISA
enzyme-linked immunosorbent assay
- RPLA
reversed passive latex agglutination test
- SRID
single radial immunodiffusion 相似文献
924.
Latimer KS Bounous DI Colatos C Carmichael KP Howerth EW 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》1996,25(1):23-26
Extreme eosinophilia with disseminated eosinophilic granulomatous disease is described in a 4-year-old Arabian mare. Clinical signs included weight loss, coughing, jugular distention, and ventral edema. Cutaneous lesions were not observed. Eosinophilic inflammation was observed in cytologic specimens from the respiratory tract, body cavities, and lymph nodes. At necropsy, a 20-cm diameter intrathoracic mass was observed. Smaller nodules were present in the lymph nodes, liver, spleen, adrenal glands, pancreas, and skeletal muscle. Histologically, these masses and nodules were characterized by infiltrates of eosinophils, macrophages, and multinucleated giant cells, reactive fibroplasia; and multifocal eosinophilic coagula. Microscopically, mild eosinophilic infiltrates were observed in sections of stomach, small intestine, colon, and pleura; however, gross lesions were not observed in these tissues at necropsy. The etiology of the extreme eosinophilia and disseminated eosinophilic granulomatous disease in this horse was not determined. 相似文献
925.
926.
927.
Glanz J 《Science (New York, N.Y.)》1994,263(5145):321-322
928.
929.
Amelinckx S Zhang XB Bernaerts D Zhang XF Ivanov V Nagy JB 《Science (New York, N.Y.)》1994,265(5172):635-639
The concept of a spatial-velocity hodograph is introduced to describe quantitatively the extrusion of a carbon tubule from a catalytic particle. The conditions under which a continuous tubular surface can be generated are discussed in terms of this hodograph, the shape of which determines the geometry of the initial nanotube. The model is consistent with all observed tubular shapes and explains why the formation process induces stresses that may lead to "spontaneous" plastic deformation of the tubule. This result is due to the violation of the continuity condition, that is, to the mismatch between the extrusion velocity by the catalytic particle, required to generate a continuous tubular surface, and the rate of carbon deposition. 相似文献
930.