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991.
992.
在节水栽培条件下,研究了不同施氮量及氮肥施用时期对冬小麦产量、生育期间土壤硝态氮含量的影响。结果表明,冬小麦施氮处理产量均高于N0,N88.5 69处理产量最高,氮肥生理效率则随施氮量增加而显著降低。开花期以及成熟期各施氮处理0~100 cm土体硝态氮含量均明显高于N0,各生育期0~60 cm土层硝态氮含量均随施氮量增加而增加,开花期各处理2 m土体硝态氮含量达到最高值,成熟期20~60 cm土层相同施氮量(157.5,226.5kg/hm2)均表现为氮肥分次施用处理硝态氮含量高于一次性底施处理(N88.5 69>N157.5,N123 103.5>N226.5)。成熟期土壤硝态氮2 m土体累积量随施氮量增加显著增加,且等量氮肥分次施用显著高于一次性底施。 相似文献
993.
D. K. Papakosta 《Journal of Agronomy and Crop Science》1992,168(4):238-242
In a soil lacking indigenous Bradyrhizobium japonicum , soybean ( Glycine max [L.] Merr.) nodulation depends upon the number of rhizobia applied with the inoculum. This field study reports the effect of different rates of applied rhizobia on nodulation, dry matter and nitrogen content in soybean in a Mediterranean soil lacking B. japonicum.
Treatments included six rates of B. japonicum , ranging from 2.5 × 104 to 6.075 × 106 rhizobia cells per seed applied to the seed as peat inoculant at planting, 100 kg N ha−1 and an uninoculated control. The experiment was conducted in an Entisol soil. Regression analysis showed linear relationship between the rate of applied rhizobia and the number of the nodules per plant or the dry weight per nodule. In early stages of development (32 and 68 days after planting) plant dry weight was not affected by inoculation rate. At harvest a rate of 7.5 × 104 rhizobia cells per seed was necessary for maximum total and stover dry weight. A higher rate, 6.75 × 105 rhizobia cells per seed, was required to obtain maximum grain yield, total N content in plant tops and grain N content. Grain percentage N was increased up to 2.025 × 106 rhizobia cells per seed. Nitrogen application increased grain yield, total N content and grain N content at the same level as the lower inoculation rate. 相似文献
Treatments included six rates of B. japonicum , ranging from 2.5 × 10
994.
为了明确吡草醚对棉花催熟效果,探明吡草醚催熟对棉花产量和品质性状的影响,采用田间试验及室内药效测定方法,对施用2%吡草醚ME后棉花叶片脱落速度、吐絮率及产量结果等进行分析。结果显示:2%吡草醚ME脱叶、吐絮效果明显,与常规脱叶剂噻苯隆相当;药后30天收获籽棉产量比清水对照区增加10.75%~21.60%,霜前花比例增加显著;单铃重减小、僵桃增多;对衣分、纤维长度等品质指标影响不明显。吡草醚具有安全性好、脱叶速度快、棉铃吐絮早、大幅度提高霜前花比例等优点,可以作为一种新型的棉花脱叶催熟剂推广应用。 相似文献
995.
996.
Vernonia galamensis is a potential new industrial crop growing wild in Ethiopia. The seed oil is rich in vernolic acid, an epoxy fatty acid, which is of interest for oleochemical uses. Basic information on the reproductive system of Vernonia is still very limited. The amount of natural outcrossing was estimated at two locations in Ethiopia (Alemaya and Babile) using flower colour as a marker. Single plants with white flowers, which is a monogenic recessive trait, were planted in plots with normal pink flowers and the outcrossing rate was estimated from the frequency of pink‐flowered plants in the progeny of the white‐flowered plants. Estimates of the natural outcrossing rate ranged between individual plants from 3.5 to 16% at Alemaya and 2.5 to 12% at Babile. Vernonia galamensis can be classified as a mainly self‐pollinated species. 相似文献
997.
Compensatory Growth Responses During Reproductive Phase of Cowpea after Relief of Water Stress 总被引:1,自引:0,他引:1
Unpredictable drought affects growth and yield of dryland cowpea ( Vigna unguiculata [L.] Walp.) during rainy season. With the objective of identifying compensatory growth responses after relief of water stress, pot-grown plants (cv. C-752) were water-stressed at flowering, and physiological responses, short term dry matter partitioning upon relief of water stress, and productivity at maturity were studied. Water stress decreased, to varying degrees, leaf water potential, stomatal conductance, photosynthesis rate and transpiration rate. Recovery in assimilation lagged behind that in water relations. Assimilate supply seemed to be limiting early pod growth upon relief of water stress due to low photosynthesis rate, reduced leaf area per pod, and increased partitioning to leaf expansion. However, later pod growth was not limited by assimilate supply and final dry matter per pod was similar in both non-stressed and stress-affected plant. Cowpea exhibited the following growth responses during pod-fill stage upon relief of water stress: 1. increase in leaf area, 2. shift in dry matter partitioning in favour of leaf expansion, 3. extended green leaf duration, and 4. increase in pod number. These partially compensating physiological responses probably ensure reasonable productivity of dryland cowpea during rainy season. 相似文献
998.
According to different deformation conditions required in working process for manufacturing of 3104 aluminum alloy, the authors design the simulation experiments of hot rolling process at different deformation temperature and strain rates, analyze the relationships of deformation resistance, flow stress and strain rate, deformation temperature when alloy deformation. Based on experimental data analysis, it was concluded that the dominant factors affecting flow stress were the strain rate and deformation temperature, and the two parameters were also important for deforming process control. 相似文献
999.
1000.
Employing the Gleeble-1500D thermal analogue machine and the STA449 synthesis thermal analyzer,the study on hot ductility and parts of thermology performance of 20CrMo steel has been carried out , many consulted foundation data has been obtained, the optimum ductility temperature arrange has been found, contraction of cross sectional area is only 30% between 600 degree and 775 degree, but contraction of cross sectional area is more than 80% between 800 degree and 1 250 degree, contraction of cross sectional area drops to under 60% rapidly between 1 350 degree and melting point,a curve is drawn showing the relationshi Pbetween heat capacity and the variation of temperature for the first time, the counting formulas of the heat capacity are regressed by disjunction. A curve is drawn showing the relationshi Pbetween the coefficient of thermal expansion and the variation of temperature, and their application in continuous casting is discussed herein. 相似文献