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Nitrogen (N) deficiency is one of the most yield-limiting nutrients in upland rice growing regions word wide. A greenhouse experiment was conducted with the objective to evaluate nineteen upland rice (Oryza sativa. L.) genotypes for N use efficiency. The soil used in the experiment was an Oxisol and two N levels used were without N application (low level) and an application of 400 mg N kg?1 of soil (high level). Grain yield and yield components and N uptake parameters were significantly affected by N and genotype treatments. Regression analysis showed that plant height, shoot dry weight, number of panicles per pot, number of grains per panicle, grain harvest index, N uptake in shoot and grain were having significant positive relation with grain yield. Nitrogen concentration of 6.4 g kg?1 in the shoot is established as deficient level and 9.5 g kg?1 as sufficient level at harvest. Agronomic efficiency of N (grain yield/unit of N applied) and N utilization efficiency (physiological efficiency X apparent recovery efficiency) were significantly different among genotypes. These two N use efficiencies were having significant quadratic relationship with grain yield. Soil pH, exchangeable soil Ca and base saturation were having significantly positive association with grain yield. However, soil extractable phosphorus (P), potassium (K), hydrogen (H+), aluminum (Al) and cation exchange capacity were having significantly negative association with grain yield. 相似文献
104.
山西省西山地区退耕还林还草后续产业的发展与保障问题分析 总被引:1,自引:0,他引:1
赵艺学 《中国生态农业学报》2012,20(3):378-383
本文通过随机抽取5个典型县区的有关数据,从退耕与林草建设的模式入手,利用比较和综合分析的方法,分析了山西省西山地区以林牧业发展为主的退耕还林还草后续产业的现状和趋势,以及后续产业发展的保障性等问题。结果认为,从整体上看,山西省西山地区退耕还林还草后续产业发展过程可分为倒退式发展(2000—2003年)、明显加快发展(2003—2006年)和迅速发展(2006—2009年)3个时段。选定的典型县区总体情况表明,在区域耕地减少、人口增多的情况下,粮食总产量和人均粮食产量均有所增长,表明典型区域耕地质量明显提高和后续产业持续发展的趋势;从典型县区个案情况看,在某一定时段内粮食总产量和人均粮食产量均出现不同幅度的负增长态势,也显示了该区后续产业存在严重的发展问题。最后提出了稳定耕地数量、保障人均粮食拥有量是后续产业发展的根本,以及需要进一步分析的主要问题。 相似文献
105.
B. GLENCROSS D. BLYTH S. TABRETT N. BOURNE S. IRVIN M. ANDERSON T. FOX‐SMITH R. SMULLEN 《Aquaculture Nutrition》2012,18(4):388-399
This study examined the digestibilities of whole diets and ingredients of a range of starch/cereal grains when fed to barramundi (Lates calcarifer). The ingredients included wheat, oats, sorghum, triticale, barley, among others. Twelve diets were prepared using a twin‐screw extruder to mimic modern aquafeed‐manufacturing processes. The diets were then fed to juvenile barramundi and the faeces collected using stripping methods. Significant variability in the digestible energy and starch value was seen among the test ingredients and diets. Diet starch digestibility ranged from 49.1% to 93.9%. Ingredient starch digestibility ranged from 18.0% to 96.5%. Among the different starch ingredients, a strong negative correlation between the ingredient amylopectin content and starch digestibility of that ingredient was observed. This relationship was also mirrored by a similar relationship, although not as strong, between total starch and starch digestibility. This study demonstrates that barramundi have limited ability to digest starch and that there is an effect of inclusion level on the ability of the animal to digest this nutrient. But it also demonstrates that there is a wide range of cereal sources that can be effectively used as starch sources in extruded diets for this species. 相似文献
106.
Luke A Roy ré Bordinhon Daranee Sookying D Allen Davis Travis W Brown & Gregory N Whitis 《Aquaculture Research》2009,40(4):496-503
The replacement of marine proteins with vegetable proteins or terrestrial animal byproducts in aquaculture diets has been gaining momentum. This study examines the viability of replacing fish meal in shrimp production diets with alternative protein sources (combinations of vegetable proteins) in inland low salinity waters of west Alabama. The test diets were formulated to contain 36% protein and 8% lipid. The basal diet contained 10% fish meal. The fish meal was then replaced (on a weight to weight basis) with poultry meal (PM), pea meal or distiller's dried grain with solubles (DDGS). Two separate experiments (laboratory trial and farm trial) were devised to test the efficacy of the diets for Litopenaeus vannamei reared in low salinity waters. The laboratory trial was conducted at the E. W. Shell Fisheries Research Station in Auburn, Alabama, USA, whereas the farm trial examined the same diets in an outdoor flow-through system at a low salinity shrimp farm in west Alabama. Results indicate no significant differences in shrimp growth, weight gain, survival or feed conversion ratio among dietary treatments, suggesting that PM, pea meal and DDGS can serve as alternatives to fish meal as a protein source for shrimp reared in low salinity environments. 相似文献
107.
108.
The global seafood industry, influenced by consumer demand, is closely linked to the global fishing industry, which determines the variety of fish available for consumption. The recently revealed issue of seafood mislabelling threatens to weaken this link by removing consumer power to influence patterns of fisheries exploitation through informed choice. Recognizing this, there is an urgent need to go beyond the mere documentation of the phenomenon and learn more about the origins of this problem and the nature of factors influencing its occurrence to develop solutions. In an attempt to understand seafood mislabelling more thoroughly in Europe, 226 cod products were purchased from Ireland and the UK, genetically identified using a DNA barcoding technique (COI barcoding gene), and species identification results were compared against product labels. Cod mislabelling proved more severe in Ireland than in the UK (28.4% vs. 7.4%). Moreover, whereas data show that in Ireland, cheaper species are sold as cod, in the UK, threatened Atlantic cod (Gadus morhua) may be sold as ‘sustainably sourced’ Pacific cod. Considering these countries operate under the same EU policies for seafood traceability and labelling, it is likely that this situation has been influenced by heightened consumer awareness in the UK, which has created an environment where mislabelling is discouraged. In addition to identifying samples, traceability information from packaged cod was used to trace products back to supplying companies. Although inconclusive in determining blame, this exercise has demonstrated that using traceability information can add explanatory power when attempting to determine responsibility for the occurrence of mislabelling. 相似文献
109.
QIU Jian-jun WANG Li-gang LI Hu TANG Hua-jun LI Chang-sheng Eric Van Ranst 《中国农业科学(英文版)》2009,8(4):464-471
This study quantified the impacts of soil organic carbon (SOC) content on the grain yield of crops using a biogeochemical model (DNDC, denitrification-decomposition). Data on climate, soil properties, and farming management regimes of cropping systems were collected from six typical agricultural zones (northeast, north, northwest, mid-south, east and southwest regions of China, respectively) and integrated into a GIS database to support the model runs. According to the model, if the initial SOC content in the cropland was increased by 1 g C kg^-1, the crop yield may be increased by 176 kg ha^-1 for maize in the northeast region, 454 kg ha^-1 for a maize-wheat rotation in the north region, 328 kg ha^-1 for maize in the northwest region, 185 kg ha^-1 for single-rice in the mid-south region, 266 kg ha^-1 for double-rice in east region, and 229 kg ha^-1 for rice and wheat rotation in southwest region. There is a great potential for enhancing the crop yield by improving the SOC content in each region of China. 相似文献
110.
试验旨在探索研究不同的水深和容器的透光性是否影响望天眼金鱼最终成功翻眼率,并通过杂交试验,探讨金鱼望天眼性状是否稳定遗传。试验首先选取红望天眼金鱼两雌一雄和一雄偏龙睛五花金鱼,进行人工混合繁殖,随机选取后代分四组,分别在透明玻璃缸水深15 cm(A)、透明玻璃缸水深30 cm(B)、不透光塑缸水深15 cm(C)和不透光塑缸水深30 cm(D)环境中养殖290 d,统计最终金鱼成功翻眼率,进行双因素方差分析,同时进行望天眼金鱼与翻眼不成功的介于望天和龙睛中间体的金鱼进行正反交和各自自交,统计后代最终的眼睛性状。结果显示:水深对望天眼金鱼成功翻眼率影响极显著,容器透光性对其影响不显著;亲本翻眼程度越大,其后代望天比例越高,表明望天眼性状受遗传影响较大,并且一定程度上受母体遗传效应影响。 相似文献