全文获取类型
收费全文 | 112篇 |
免费 | 4篇 |
专业分类
林业 | 6篇 |
农学 | 8篇 |
6篇 | |
综合类 | 31篇 |
农作物 | 8篇 |
水产渔业 | 13篇 |
畜牧兽医 | 25篇 |
园艺 | 5篇 |
植物保护 | 14篇 |
出版年
2023年 | 1篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2014年 | 7篇 |
2013年 | 8篇 |
2012年 | 9篇 |
2011年 | 5篇 |
2010年 | 2篇 |
2009年 | 5篇 |
2008年 | 9篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2003年 | 3篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1967年 | 1篇 |
1965年 | 2篇 |
1959年 | 1篇 |
1892年 | 1篇 |
排序方式: 共有116条查询结果,搜索用时 343 毫秒
21.
The genome sequence of Drosophila melanogaster 总被引:2,自引:0,他引:2
Adams MD Celniker SE Holt RA Evans CA Gocayne JD Amanatides PG Scherer SE Li PW Hoskins RA Galle RF George RA Lewis SE Richards S Ashburner M Henderson SN Sutton GG Wortman JR Yandell MD Zhang Q Chen LX Brandon RC Rogers YH Blazej RG Champe M Pfeiffer BD Wan KH Doyle C Baxter EG Helt G Nelson CR Gabor GL Abril JF Agbayani A An HJ Andrews-Pfannkoch C Baldwin D Ballew RM Basu A Baxendale J Bayraktaroglu L Beasley EM Beeson KY Benos PV Berman BP Bhandari D Bolshakov S Borkova D Botchan MR Bouck J 《Science (New York, N.Y.)》2000,287(5461):2185-2195
The fly Drosophila melanogaster is one of the most intensively studied organisms in biology and serves as a model system for the investigation of many developmental and cellular processes common to higher eukaryotes, including humans. We have determined the nucleotide sequence of nearly all of the approximately 120-megabase euchromatic portion of the Drosophila genome using a whole-genome shotgun sequencing strategy supported by extensive clone-based sequence and a high-quality bacterial artificial chromosome physical map. Efforts are under way to close the remaining gaps; however, the sequence is of sufficient accuracy and contiguity to be declared substantially complete and to support an initial analysis of genome structure and preliminary gene annotation and interpretation. The genome encodes approximately 13,600 genes, somewhat fewer than the smaller Caenorhabditis elegans genome, but with comparable functional diversity. 相似文献
22.
About 100 pure-bred samples of nine varieties of pulses raised in different state agricultural farms of India in 1957, when analyzed, indicated variations in the protein content of a single variety extending up to 60 percent in some cases, depending upon the strain and the locality where grown. 相似文献
23.
J Christensen-Dalsgaard W Dappen SV Ajukov ER Anderson HM Antia S Basu VA Baturin G Berthomieu B Chaboyer SM Chitre AN Cox P Demarque J Donatowicz WA Dziembowski M Gabriel DO Gough DB Guenther JA Guzik JW Harvey F Hill G Houdek CA Iglesias AG Kosovichev JW Leibacher P Morel CR Proffitt J Provost J Reiter EJ Rhodes FJ Rogers IW Roxburgh MJ Thompson RK Ulrich 《Science (New York, N.Y.)》1996,272(5266):1286-1292
Data from the Global Oscillation Network Group (GONG) project and other helioseismic experiments provide a test for models of stellar interiors and for the thermodynamic and radiative properties, on which the models depend, of matter under the extreme conditions found in the sun. Current models are in agreement with the helioseismic inferences, which suggests, for example, that the disagreement between the predicted and observed fluxes of neutrinos from the sun is not caused by errors in the models. However, the GONG data reveal subtle errors in the models, such as an excess in sound speed just beneath the convection zone. These discrepancies indicate effects that have so far not been correctly accounted for; for example, it is plausible that the sound-speed differences reflect weak mixing in stellar interiors, of potential importance to the overall evolution of stars and ultimately to estimates of the age of the galaxy based on stellar evolution calculations. 相似文献
24.
Samarium-neodymium data for nine granitic and tonalite gneisses occurring as remnants within the Singhbhum granite batholith in eastern India define an isochron of age 3775 +/- 89 x 10(6) years with an initial (143)Nd/(144)Nd ratio of 0.50798 +/- 0.00007. This age contrasts with the rubidium-strontium age of 3200 x 10(6) years for the same suite of rocks. On the basis of the new samarium-neodynium data, field data, and petrologic data, a scheme of evolution is proposed for the Archean crust in eastern India. The isotopic data provide evidence that parts of the earth's mantle were already differentiated with respect to the chondritic samarium-neodymium ratio 3800 x l0(6) years ago. 相似文献
25.
Becker L Poreda RJ Basu AR Pope KO Harrison TM Nicholson C Iasky R 《Science (New York, N.Y.)》2004,304(5676):1469-1476
The Bedout High, located on the northwestern continental margin of Australia, has emerged as a prime candidate for an end-Permian impact structure. Seismic imaging, gravity data, and the identification of melt rocks and impact breccias from drill cores located on top of Bedout are consistent with the presence of a buried impact crater. The impact breccias contain nearly pure silica glass (SiO2), fractured and shock-melted plagioclases, and spherulitic glass. The distribution of glass and shocked minerals over hundreds of meters of core material implies that a melt sheet is present. Available gravity and seismic data suggest that the Bedout High represents the central uplift of a crater similar in size to Chicxulub. A plagioclase separate from the Lagrange-1 exploration well has an Ar/Ar age of 250.1 +/- 4.5 million years. The location, size, and age of the Bedout crater can account for reported occurrences of impact debris in Permian-Triassic boundary sediments worldwide. 相似文献
26.
Tropical Animal Health and Production - Search for cost-effective, eco-friendly and sustainable plant resources as potential feedstuff to replace fishmeal in the formulation of feed for fish has... 相似文献
27.
28.
Samarium-neodymium isotopic data on whole rocks and minerals of the Sudbury Complex in Canada gave an igneous crystallization age of 1840 +/- 21 x 10(6) years. The initial epsilon neodymium values for 15 whole rocks are similar to those for average upper continental crust, falling on the crustal trend of neodymium isotopic evolution as defined by shales. The rare earth element concentration patterns of Sudbury rocks are also similar to upper crustal averages. These data suggest that the Sudbury Complex formed from melts generated in the upper crust and are consistent with a meteoritic impact. 相似文献
29.
DO Gough AG Kosovichev J Toomre E Anderson HM Antia S Basu B Chaboyer SM Chitre J Christensen-Dalsgaard WA Dziembowski A Eff-Darwich JR Elliott PM Giles PR Goode JA Guzik JW Harvey F Hill JW Leibacher MJPFG Monteiro O Richard T Sekii H Shibahashi M Takata MJ Thompson S Vauclair SV Vorontsov 《Science (New York, N.Y.)》1996,272(5266):1296-1300
Global Oscillation Network Group data reveal that the internal structure of the sun can be well represented by a calibrated standard model. However, immediately beneath the convection zone and at the edge of the energy-generating core, the sound-speed variation is somewhat smoother in the sun than it is in the model. This could be a consequence of chemical inhomogeneity that is too severe in the model, perhaps owing to inaccurate modeling of gravitational settling or to neglected macroscopic motion that may be present in the sun. Accurate knowledge of the sun's structure enables inferences to be made about the physics that controls the sun; for example, through the opacity, the equation of state, or wave motion. Those inferences can then be used elsewhere in astrophysics. 相似文献
30.
The effect of the nitrogen nutrition of stock plants of Justicia gendarussa L. on the rooting of cuttings was studied in sand culture under high, medium and low levels of nitrogen.Nitrogen starvation induced rooting. Exogenous application of the auxins IAA (indol-3yl-acetic acid), IBA (indol-3yl-butyric acid) and NAA (naphth-lyl-acetic acid) greatly increased the rooting response of cuttings from-stock plants grown with small amounts of nitrogen.The root-promoting effect of a low nitrogen supply was associated with a retardation of growth in the stock plants from which the cuttings were made. High C/N (total available carbohydrates/total nitrogen) and P/N (total phosphorus/total nitrogen) ratios increased anthocyanin pigmentation in the shoot, and increased rooting cofactor activity in the tissues of cuttings. The phenolic compounds, ferulic acid, p-hydroxybenzoic acid and p-coumaric acid were present in the shoots of all three nutritional treatments and acted as important cofactors in the cuttings. In general, rooting cofactor activity was inversely related to nitrogen supply and the activity was highest under low nitrogen.The cuttings taken from plants grown under different levels of nitrogen interacted differentially with the exogenously applied auxins. 相似文献