全文获取类型
收费全文 | 3184篇 |
免费 | 160篇 |
国内免费 | 2篇 |
专业分类
林业 | 94篇 |
农学 | 56篇 |
基础科学 | 18篇 |
294篇 | |
综合类 | 846篇 |
农作物 | 136篇 |
水产渔业 | 86篇 |
畜牧兽医 | 1671篇 |
园艺 | 42篇 |
植物保护 | 103篇 |
出版年
2021年 | 27篇 |
2020年 | 32篇 |
2019年 | 31篇 |
2018年 | 38篇 |
2017年 | 41篇 |
2016年 | 40篇 |
2015年 | 33篇 |
2014年 | 35篇 |
2013年 | 111篇 |
2012年 | 104篇 |
2011年 | 136篇 |
2010年 | 47篇 |
2009年 | 60篇 |
2008年 | 134篇 |
2007年 | 141篇 |
2006年 | 159篇 |
2005年 | 126篇 |
2004年 | 105篇 |
2003年 | 96篇 |
2002年 | 116篇 |
2001年 | 80篇 |
2000年 | 75篇 |
1999年 | 83篇 |
1998年 | 37篇 |
1997年 | 31篇 |
1996年 | 31篇 |
1995年 | 39篇 |
1992年 | 79篇 |
1991年 | 75篇 |
1990年 | 58篇 |
1989年 | 57篇 |
1988年 | 52篇 |
1987年 | 55篇 |
1986年 | 52篇 |
1985年 | 70篇 |
1984年 | 37篇 |
1983年 | 37篇 |
1982年 | 22篇 |
1981年 | 19篇 |
1980年 | 22篇 |
1979年 | 24篇 |
1976年 | 21篇 |
1974年 | 24篇 |
1973年 | 40篇 |
1972年 | 29篇 |
1971年 | 34篇 |
1970年 | 25篇 |
1969年 | 27篇 |
1967年 | 22篇 |
1966年 | 24篇 |
排序方式: 共有3346条查询结果,搜索用时 62 毫秒
61.
W W Miller J S Wilkins L L Dunham 《Journal of the Association of Official Analytical Chemists》1975,58(1):10-18
Residues of isopropyl (2E,4E)-11-methoxy-3,7,11-trimethyl-2,4-dodecadienoate (Altosid) insect growth regulator are determined in waters, soils, plants, milk, eggs, fish, shellfish, poultry and cattle tissues, blood, urine, and feces. Acetonitrile is the primary extraction solvent for all samples. Residues are extracted by high-speed blending followed by vacuum filtration. Fatty extracts are subjected to cold-temperature precipitation and filtration. Samples are cleaned up by petroleum ether partitioning and Florisil and neutral alumina chromatography. The concentrated eluants are analyzed by gas-liquid chromatography (GLC) on columns of differing polarity, using hydrogen flame ionization detectors. The identity of suspected residues is confirmed by additional GLC and by mass fragmentography. The lower limits of detection were: water samples, 0.0004-0.001 ppm; soils, blood, and urine, 0.001 ppm; forage grasses, forage legumes, and rice foliage, 0.005 ppm; and milk, eggs, fish, shellfish, poultry and cattle tissues, and feces, 0.010 ppm. 相似文献
62.
63.
64.
65.
66.
67.
68.
D.G.M. Miller 《African Zoology》2013,48(3):139-142
Basking activity in the turtle Pelomedusa subrufa L. apparently is initiated by the presence of a suitable heat source, whereas subsequent basking is largely determined by prevailing environmental temperatures as well as requirements for avoiding overheating. 相似文献
69.
大麦黄矮病毒(BYDV) cDNA的合成、克隆及初步应用 总被引:6,自引:0,他引:6
以大麦黄矮病毒二叉蚜和麦长管蚜专化株的病毒核酸为模板,以小牛胸腺DNA为引物,合成cDNA的第一条链,再用缺口翻译法合成第二条链,然后采用加装BamH1人工接头的方法将ds-cDNA插入到质粒载体pUC8中,重组质粒于大肠杆菌JM—83中进行克隆,以克隆的颜色变化选择含有外源DNA的克隆,再用病毒核酸制备的探针筛选真正病毒cDNA插入的克隆。重组质粒中ds-DNA的插入长度在300—1600bp之间。用缺口翻译法制备质粒DNA分子探针检测同源病毒液,反应灵敏度在100pg-1ng之间。应用cDNA探针检测不同病毒和病毒株系,从中筛选出黄矮病毒株系专化克隆系,黄矮病毒专化克隆系和黄矮病毒组专化克隆系. 相似文献
70.
Meurs KM Miller MW Wright NA 《Journal of the American Veterinary Medical Association》2001,218(5):729-732
OBJECTIVE: To determine clinical features of dilated cardiomyopathy (DCM) in Great Danes and to determine whether DCM is familial in this breed. DESIGN: Retrospective study. ANIMALS: 17 Great Danes with DCM. PROCEDURE: Medical records of Great Danes in which DCM was diagnosed on the basis of results of echocardiography (fractional shortening < 25%, end-systolic volume index > 30 ml/m2 of body surface area) were reviewed. Pedigrees were obtained for affected animals, as well as for other Great Danes in which DCM had been diagnosed. RESULTS: Dilated cardiomyopathy appeared to be familial and was characterized by ventricular dilatation, congestive heart failure (left-sided or biventricular), and atrial fibrillation. Pedigree analysis suggested that DCM was inherited as an X-linked recessive trait, but the mode of inheritance could not be definitively identified. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that DCM may be an X-linked recessive trait in Great Danes. Thus, dogs with DCM probably should not be used for breeding, and female offspring of affected dogs should be used cautiously. Male offspring of affected females are at an increased risk of developing DCM and should be evaluated periodically for early signs of disease. Results of pedigree analysis were preliminary and should be used only as a guide for counseling breeders, rather than as a basis for making breeding decisions. 相似文献