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961.
《植物养料与土壤学杂志》2017,180(2):220-230
Standard procedures to assess P availability in soils are based on batch experiments with various extractants. However, in most soils P nutrition is less limited by bulk stocks but by strong adsorption and transport limitation. The basic principle of root‐phosphate uptake is to strip phosphate locally from the solid phase by forming a radial depletion zone in the soil solution, optionally enhanced by release of mobilizing substances. Microdialysis (MD), a well‐established method in pharmacokinetics, is capable to mimic important characteristics of P root uptake. The sampling is by diffusional exchange through a semipermeable membrane covering the probes with their sub‐mm tubular structure. Additionally, the direct environment of the probe can be chemically modified by adding, e.g ., carboxylates to the perfusate. This study is the first approach to test the applicability of MD in assessing plant available phosphate in soils and to develop a framework for its appropriate use.We used MD in stirred solutions to quantify the effect of pumping rate, concomitant ions, and pH value on phosphate recovery. Furthermore, we measured phosphate yield of top‐soil material from a beech forest, a non‐fertilized grassland, and from a fertilized corn field. Three perfusates have been used based on a 1 mM KNO3 solution: pure (1), with 0.1 mM citric acid (2), and with 1 mM citric acid (3). Additionally, a radial diffusion model has been parametrized for the stirred solutions and the beech forest soil.Results from the tests in stirred solutions were in good agreement with reported observations obtained for other ionic species. This shows the principal suitability of the experimental setup for phosphate tests. We observed a significant dependency of phosphate uptake into the MD probes on dialysate pumping rate and on ionic strength of the outside solution. In the soils, we observed uptake rates of the probes between 1.5 × 10−15 and 6.7 × 10−14 mol s−1 cm−1 in case of no citrate addition. Surprisingly, median uptake rates were mostly independent of the bulk soil stocks, but the P‐fertilized soil revealed a strong tailing towards higher values. This indicates the occurrence of hot P spots in soils. Citrate addition increased P yields only in the higher concentration but not in the forest soil. The order of magnitude of MD uptake rates from the soil samples matched root‐length related uptake rates from other studies. The micro‐radial citrate release in MD reflects the processes controlling phosphate mobilization in the rhizosphere better than measurements based on “flooding” of soil samples with citric acid in batch experiments. Important challenges in MD with phosphate are small volumes of dialysate with extremely low concentrations and a high variability of results due to soil heterogeneity and between‐probe variability. We conclude that MD is a promising tool to complement existing P‐analytical procedures, especially when spatial aspects or the release of mobilizing substances are in focus. 相似文献
962.
《Journal of Crop Improvement》2013,27(1):51-65
Abstract Only a few studies have been conducted in which regenerability of barley has been examined. In the current study, 17 barley genotypes (nine two-row malting type: Aster, Emon, Ruen, Jubiley, PV101, Körten, Krassi 2, Perun and Igri, and eight six-row feed types: Karnobat, Hemus, Jerun, Veslets, Aheloi 2, Diana, Panagon, and Izrgev) were evaluated for tissue-culture response from seedlings during a three-year period. Regenerable calli were obtained from all tested genotypes. Although there was much variation in regeneration capacity among the cultivars, plants were obtained from all cultivars. The majority of green plants grown to maturity were fertile and normal in appearance. The frequency of embryogénie callus induction and regenerability was influenced by genotype and growth conditions of the donor plants. Genotype was the most important determinant of the in vitro response. The best in vitro performance, based on ability to form regenerable calli and to regenerate plants was observed for Ruen, Aster, and Emon. 相似文献
963.
964.
开瓶炼苗对菜用大黄组培苗气孔特性的影响 总被引:2,自引:0,他引:2
研究了菜用大黄组培苗开瓶炼苗过程中叶片气孔的特性。结果表明,菜用大黄组培苗经直接开瓶炼苗0~14 d,气孔大小、气孔长径、气孔宽径随开瓶炼苗时间的延长而逐渐减小,并趋向稳定;气孔的关闭率随开瓶时间的延长而迅速增加,达到76.5%;14 d炼苗结束后,叶表皮细胞密度显著增加,气孔密度与气孔指数稍有增加,但不显著。闭瓶炼苗7 d、然后开瓶炼苗7 d可以较快恢复菜用大黄组培苗叶片气孔关闭的适应能力;显微观察发现,不同开瓶时间处理对叶片表皮气孔的细胞结构有明显影响,有光环境与无光环境对炼苗最终没有显著影响。 相似文献
965.
Jeremy Midgley Huyam Altayeb Patrick Mbosso 《African Journal of Range and Forage Science》2016,33(2):127-129
Pseudo-galls of three East African acacia (Vachellia) species were compared to determine the correlates of gall colour and their potential defensive functions. Although all three species produce white thorns, the pseudo-galls of V. gerrardii and V. drepanolobium are dark coloured. In contrast, pseudo-galls of V. seyal var. fistula are white. Associated with this, they are thin-walled and poorly used by aggressive mutualistic ants. We suggest that this weak functionality is compensated for by the highly visible white colour. This aposematism may also involve mimicry as only the fistula variety of V. seyal has galls and only this variety co-occurs with other Vachellia species that have functional galls. Vachellia seyal seyal does not have pseudo-galls and this variety does not occur with other Vachellia species that have pseudo-galls. 相似文献
966.
记述了1994年采自新疆布尔津,贾登玉,南山林场等地部分植物寄生真菌的35个种。从采集的标本中初步鉴定出35个种,其中白粉菌16种,锈菌13种,其他菌类6种。其中有5个种为新疆新记录,并对其进行了较详细的特征描述。 相似文献
967.
以杂交油菜秦油2 号和普通油菜中油821 为试验材料,研究了在施硼砂的基础上喷施植物生长调控剂对油菜的生物学效应- 结果表明:喷施多效唑(MET)使油菜叶片的气孔数、有效荚果数大幅度增加,对千粒重影响不明显,但使荚果内的表现粒数明显减少,尤其使秦油2 号的成棵率极显著降低,且减产达显著水平;喷施802 使油菜的有效荚果数和千粒重增加,但使叶片的气孔数和荚果内的表现粒数减少,增产效果不显著;喷施增产菌除使千粒重有增加的趋势外,但使中油821 的成棵率极显著降低,增产效果也不显著 相似文献
968.
969.
北方城市地被植物应用质量评价方法探讨 总被引:5,自引:0,他引:5
根据地被植物固有的特征和北方城市配置应用特点,将地被植物分为基础型地被、骨干型地被和点缀型地被3类。运用频数统计法选择株高、生育期、观赏价值、绿色期、覆盖力、生长势、适应性、养护频度8项指标,构建了地被植物外观质量、生态质量和使用质量3大指标体系。制定评价标准,采用综合指数评价法,验证地被植物的质量等级。通过实例分析验证,该质量评价指标体系和评价方法具有较强的科学性和可操作性,评价结果符合客观实际,对于北方城市地被植物的评价选择应用,具有普遍的适应性和推广价值。 相似文献
970.
研究了白三叶无性系植物种群,在相互连接的分株之间生理上相互依存的程度。结果显示子代在生理上取决于母株资源的转移,这一依赖性随时间而下降。相互连接的分株,一部分被遮荫至10%,而照光分株光合速率明显增加。光被限制期间,分株将重新整合,遮荫分株无性系中由其它分株提供同化物。在子代匍匐茎数目和长度上有一个权衡。当资源受限制时,产生极少较长的子代匍匐茎,结果提高了子代能够占据更有利条件的可能性。在分株之间,生理整合作用降低了子代建立所面临的危险,使同源分株在资源的可利用能力上整合到一个局部的异质环境,增加同源分株间的竞争能力,缓冲所面对的局部微生境的选择。 相似文献