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1.
Ralstonia solanacearum (RS) race 1 biovar 4 (R1bv4), causal agent of bacterial wilt in vegetable sweet potato (VSP), is often latent in VSP vines and is important in introduction of the pathogen to newly planted fields. In this study, the effects of biological and environmental factors on the distribution and multiplication of R1bv4 in VSP tissues were examined. Based on stem-injection inoculation, the R1bv4strain of NC01 could cause 49.0% and 33.0% wilting on VSP cultivars TN71 and WS, respectively. The populations of NC01 in diseased TN71 and WS were 108–109 cfu/g tissue at 28th day after inoculation. On the other hand, the R1bv4 could not cause symptom in cultivars of TN57 and VSPSL-1 vine and the NC01 was confined to near the injection sites. Temperature tests indicated that NC01 could cause 28.0% and 14.0% wilting on cultivar TN71 at 28 and 20°C, respectively. Moreover, the populations of NC01in diseased plants were 1.6 × 109 and 7.9 × 108 cfu/g tissue at 28 and 20°C, respectively. The distribution of NC01 in VSP stem indicated that the isolation frequency of NC01 was lower than 31.0% in terminal shoots or erect stems and 45.0 to 100.0% in creeping stem after 8 wks planted in infested soil (106 cfu/g soil). The results demonstrated that terminal shoots or erect stems were not common carrier for transmitting R1bv4. Furthermore, two R1bv4 strains, NC01 and HsinT01, were examined the ability for latent infection on cv. TN71. The results revealed that NC01 and HsinT01 showed different ability of latent infection on cultivar TN71. NC01 had lower percentage (46.8% and 45.1%) than HsinT01 (93.4% and 75.3%) at 20 and 28°C. 相似文献
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P. R. Warman 《Plant and Soil》1991,134(1):115-119
A field-size experiment was initiated in 1982 on an acid, low fertility Springhill silt loam to determine the effect of five
unfertilized green manure crops (alsike clover, sweet clover, single- and double-cut red clover, and buckwheat) on subsequent
oat production and soil fertility. The field was limed in 1982 and green manures were seeded (without fertilizer) in spring,
1983 in 1400 m2 strips randomly assigned within three treatment blocks. Plant tissue samples were taken from different locations in each
plot in the fall of 1983 and all crops were incorporated. In 1984 the field was separated into an upper and lower section
and each section received three rates of NPK fertilizer (0; 30-36-36; 60-72-72 kg ha-1) spread across the previous strips. Gary oats were seeded and at harvest were divided into grain and straw. The results indicated
significant effects of field sample location, green manure type and fertilizer level on oat yields. Buckwheat significantly
reduced oat production compared to the four clovers, while the highest fertilizer rate improved oat yields compared with the
other levels of fertilizers. Elemental analysis of the green manure crops and soil fertility was compared with data of the
same crops grown in more fertile, neutral soils. 相似文献
4.
茶园生态环境对红茶芳香化学物质及品质影响 总被引:7,自引:1,他引:6
国内外研究均表明,芳香化学物质是构成红茶品质的主要化学物质。茶叶中芳香化学物质的形成,与茶树品种、加工工艺密切相关。至于茶园生态环境和气象因子对红茶 相似文献
5.
湿地松(Pinus elliottii)是阳性乔木,茶树(Camellia sinensis)是阴性灌木。这两种树种间作,形成针阔、乔灌两层树冠结构的茶园复合生态系统,可以改善茶树生态条件,提高茶叶的产量和品质。但间作存在胁地现象。一般认为这是上层树木的过度遮荫和根系间的竞争造成的。为了解这两种树种根系的分布状况和相互关系,并为间作茶园的合理配置和加强这种茶园的耕作管理提供依据,我们进行了湿地松与茶树间作根系分布状况的研究。 相似文献
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The interactive effects of increased carbon dioxide (CO2) concentration and ultraviolet-B (UV-B, 280–320 nm) radiation on Acacia karroo Hayne, a C3 tree, and Themeda triandra Forsk., a C4 grass, were investigated. We tested the hypothesis that A. karroo would show greater CO2-induced growth stimulation than T. triandra, which would partially explain current encroachment of A. karroo into C4 grasslands, but that increased UV-B could mitigate this advantage. Seedlings were grown in open-top chambers in a greenhouse in ambient (360 μmol mol-1) and elevated (650 μmol mol-1) CO2, combined with ambient (1.56 to 8.66 kJ m-2 day-1) or increased (2.22 to 11.93 kJ m-2 day-1) biologically effective (weighted) UV-B irradiances. After 30 weeks, elevated CO2 had no effect on biomass of A. karroo, despite increased net CO2 assimilation rates. Interaction between UV-B and CO2 on stomatal conductance was found, with conductances decreasing only where elevated CO2 and UV-B were supplied separately. Increases in water use efficiencies, foliar starch concentrations, root nodule numbers and total nodule mass were measured in elevated CO2. Elevated UV-B caused only an increase in foliar carbon concentrations. In T. triandra, net CO2 assimilation rates were unaffected in elevated CO2, but stomatal conductances and foliar nitrogen concentrations decreased, and water use efficiencies increased. Biomass of all vegetative fractions, particularly leaf sheaths, was increased in elevated CO2. and was accompanied by increased leaf blade lengths and individual leaf and leaf sheath masses. However, tiller numbers were reduced in elevated CO2. Significantly moderating effects of elevated UV-B were apparent only in individual masses of leaf blades and sheaths, and in total sheath and shoot biomass. The direct CO2-induced growth responses of the species therefore do not support the hypothesis of CO2-driven woody encroachment of C4 grasslands. Rather, differential changes in resource use efficiency between grass and woody species, or morphological responses of grass species, could alter the competitive balance. Increased UV-B radiation is unlikely to substantially alter the CO2 response of these species. 相似文献
8.
The apoplastic fluids of field-grown Zea mays and Zea luxurians plants were isolated from surface sterilized stem tissue by centrifugation and spread on agar plates containing a nitrogen-free, defined medium. The predominant bacterium isolated from these plates was characterized further. The ability of this bacterium to fix nitrogen was confirmed by its ability to grow on a semi-solid, nitrogen-free medium and reduce 15N2 to 15NH3 and acetylene to ethylene. Protions of the nifH and 16S rRNA genes from this organism were amplified by PCR and sequenced. The nifH gene, which codes for dinitrogenase reductase, from this organism is closely related to nifH from Klebsiella pneumoniae. Similarly, the 16S rRNA gene sequences and carbon utilization tests grouped it closely with K. pneumoniae. Based an these data, the isolates from Z. mays and Z. luxurians are tentatively classified as Klebsiella spp. (Zea). The ability of this bacterium to contribute to the nitrogen economy of the corn plant is unknown. 相似文献
9.
中国茶对变形链球菌的抑菌作用 总被引:2,自引:0,他引:2
对36只spraque-Dawley鼠分4组给予诱龋饲料(Diet2000,keys),并连续5天在口腔内接种变链菌6715菌株,分别给予我国主要产茶区的三种茶浸液:龙井绿茶(B组),四川涪陵红茶(C组),乌龙茶(D组),先用0.5g茶和50ml双蒸馏水加热煮沸过滤后浸泡10分钟以及对照组(A组)用双蒸馏水为饮料喂养实验鼠。实验60天后,杀鼠观察计算鼠磨牙面的菌落形成单位(CFU)和菌斑指数(plaquescore)均显著下降。实验结果,实验组和对照组菌斑指数下降值顺序如下:C组>D组>B组>A组,并与实验组含氟量有相关性。很多研究表明变链菌是较为肯定的致龋菌、茶中氟化物对变链菌生长、粘附都有抑制作用。本研究选用茶来源广泛、价廉、无毒安全等优点,为开拓新的防龋方法进行探索。 相似文献
10.
合理用药生态控制茶小绿叶蝉主要措施与评价 总被引:10,自引:0,他引:10
合理用药生态控制茶小绿叶蝉主要措施与评价张觉晚,王沅江(湖南省茶叶研究所,长沙410145)PrincipalTechniquesofRationalUseofPesticideforEcologicalControloverTeaGresnLeaf... 相似文献