全文获取类型
收费全文 | 507篇 |
免费 | 12篇 |
国内免费 | 2篇 |
专业分类
林业 | 74篇 |
农学 | 10篇 |
基础科学 | 1篇 |
184篇 | |
综合类 | 61篇 |
农作物 | 11篇 |
水产渔业 | 12篇 |
畜牧兽医 | 109篇 |
园艺 | 12篇 |
植物保护 | 47篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 9篇 |
2019年 | 7篇 |
2018年 | 10篇 |
2017年 | 6篇 |
2016年 | 14篇 |
2015年 | 11篇 |
2014年 | 13篇 |
2013年 | 23篇 |
2012年 | 20篇 |
2011年 | 30篇 |
2010年 | 24篇 |
2009年 | 10篇 |
2008年 | 27篇 |
2007年 | 35篇 |
2006年 | 37篇 |
2005年 | 18篇 |
2004年 | 20篇 |
2003年 | 23篇 |
2002年 | 23篇 |
2001年 | 15篇 |
2000年 | 4篇 |
1999年 | 9篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1991年 | 4篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 7篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 6篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1978年 | 8篇 |
1977年 | 6篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1970年 | 2篇 |
1969年 | 3篇 |
1968年 | 2篇 |
1967年 | 3篇 |
1966年 | 7篇 |
排序方式: 共有521条查询结果,搜索用时 750 毫秒
181.
Ulrich Kleine-Kleffmann 《植物养料与土壤学杂志》2023,186(6):615-622
The birth of potash industry was 1861 in Staßfurt, Duchy of Prussia with commissioning of the first potash plant. During the mining of rock salt in Staßfurt, seams containing potassium had previously only been discovered by chance and initially treated as overburden. Until 1918, potash production was only in the German Empire with a total capacity of about 0.83 million t K. Subsequently, a successful global exploration for further potash deposits began. Large and high-quality potash deposits are found in the Northern Hemisphere in Europe, Canada, Russia, and Belarus. From around 1950 onward, the industry began to grow strongly. In 2021, the global production was about 36 million t K. More than 90% is marketed as fertilizer, mainly potassium chloride. Feeding the world's growing population requires a safe and adequate supply of fertilizer. The potash production capacities are correspondingly high and the global supply of potassium fertilizer is secured for centuries to come. 相似文献
182.
Mees A Klar T Gnau P Hennecke U Eker AP Carell T Essen LO 《Science (New York, N.Y.)》2004,306(5702):1789-1793
DNA photolyases use light energy to repair DNA that comprises ultraviolet-induced lesions such as the cis-syn cyclobutane pyrimidine dimers (CPDs). Here we report the crystal structure of a DNA photolyase bound to duplex DNA that is bent by 50 degrees and comprises a synthetic CPD lesion. This CPD lesion is flipped into the active site and split there into two thymines by synchrotron radiation at 100 K. Although photolyases catalyze blue light-driven CPD cleavage only above 200 K, this structure apparently mimics a structural substate during light-driven DNA repair in which back-flipping of the thymines into duplex DNA has not yet taken place. 相似文献
183.
Age-associated increases in collagen cross-linking and accumulation of advanced glycosylation products are both accelerated by diabetes, suggesting that glucose-derived cross-link formation may contribute to the development of chronic diabetic complications as well as certain physical changes of aging. Aminoguanidine, a nucleophilic hydrazine compound, prevented both the formation of fluorescent advanced nonenzymatic glycosylation products and the formation of glucose-derived collagen cross-links in vitro. Aminoguanidine administration to rats was equally effective in preventing diabetes-induced formation of fluorescent advanced nonenzymatic glycosylation products and cross-linking of arterial wall connective tissue protein in vivo. The identification of aminoguanidine as an inhibitor of advanced nonenzymatic glycosylation product formation now makes possible precise experimental definition of the pathogenetic significance of this process and suggests a potential clinical role for aminoguanidine in the future treatment of chronic diabetic complications. 相似文献
184.
Cuomo CA Güldener U Xu JR Trail F Turgeon BG Di Pietro A Walton JD Ma LJ Baker SE Rep M Adam G Antoniw J Baldwin T Calvo S Chang YL Decaprio D Gale LR Gnerre S Goswami RS Hammond-Kosack K Harris LJ Hilburn K Kennell JC Kroken S Magnuson JK Mannhaupt G Mauceli E Mewes HW Mitterbauer R Muehlbauer G Münsterkötter M Nelson D O'donnell K Ouellet T Qi W Quesneville H Roncero MI Seong KY Tetko IV Urban M Waalwijk C Ward TJ Yao J Birren BW Kistler HC 《Science (New York, N.Y.)》2007,317(5843):1400-1402
We sequenced and annotated the genome of the filamentous fungus Fusarium graminearum, a major pathogen of cultivated cereals. Very few repetitive sequences were detected, and the process of repeat-induced point mutation, in which duplicated sequences are subject to extensive mutation, may partially account for the reduced repeat content and apparent low number of paralogous (ancestrally duplicated) genes. A second strain of F. graminearum contained more than 10,000 single-nucleotide polymorphisms, which were frequently located near telomeres and within other discrete chromosomal segments. Many highly polymorphic regions contained sets of genes implicated in plant-fungus interactions and were unusually divergent, with higher rates of recombination. These regions of genome innovation may result from selection due to interactions of F. graminearum with its plant hosts. 相似文献
185.
Unconditioned aggression between paired animals in response to electric shock has been previously demonstrated. In this study, with the use of classical Pavlovian conditioning procedures, aggression was produced between paired rats as a response to a tone stimulus. 相似文献
186.
Krieger UK Huthwelker T Daniel C Weers U Peter T Lanford WA 《Science (New York, N.Y.)》2002,295(5557):1048-1050
Here we describe the use of Rutherford backscattering spectrometry (RBS) to measure quantitative in situ elemental profiles with high depth resolution, online and nondestructively, in volatile substances (liquid and frozen acids, ice). Samples for analysis are held in a chamber with controlled temperature and partial pressures designed to match conditions for aerosols in Earth's atmosphere. This technique is demonstrated in studies of water solubility in sulfuric acid, hydrochloric acid (HCl) on ice surfaces, the formation of a HCl-hexahydrate surface layer on evaporating HCl-doped ice, and the diffusion of water through this layer. 相似文献
187.
A water culture technique was developed for the study of the nutrient requirements of the potato plant. Tuber formation was avoided by pinching off the stolons as they developed and hence vegetative growth could be studied without the complication of abnormal tuber formation in the culture solution. The K deficiency symptoms obtained by this method were essentially the same as those observed for field grown plants. 相似文献
188.
189.
Bernhard Ulrich 《植物养料与土壤学杂志》1988,151(3):171-176
Eco-chemical parameters of soils Parameters are described which allow the ecochemical characterization of the mineral substance, of the pool of mobilizable surface bound ions, and of the pool of dissolved ions. In the soil solution (dissolved ion pool) distinction is made between parameters quantifying nutrient and acid stress and indication parameters. Indication parameters, which are derived from the anion composition of the dissolved ion pool, allow the identification of the anion source. Anion sources may be located in the ecosystem itself (HCO3?, NO3?, organic anions), may be atmospheric deposition (SO42?, NO3?, Cl?) and may originate from fertilization. 相似文献
190.