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21.
Stephen AC Marklevitz Elizabete Almeida Joanna Flemming Jocelyne Hellou 《Journal of Soils and Sediments》2008,8(2):92-97
Background, Aims and Scope
Our study determined if and when an avoidance or attraction behavioural response would be displayed by Ilyanassa obsoleta when presented with a choice between harbour and reference sediments. Our goal was to develop a non-lethal approach that could be used in future assessments of the environmental quality of field sediments. 相似文献22.
Jennifer Anne Davidson Rohan B. E. Kimber 《European journal of plant pathology / European Foundation for Plant Pathology》2007,119(1):99-110
Ascochyta blight causes significant yield loss in pulse crops worldwide. Integrated disease management is essential to take
advantage of cultivars with partial resistance to this disease. The most effective practices, established by decades of research,
use a combination of disease-free seed, destruction or avoidance of inoculum sources, manipulation of sowing dates, seed and
foliar fungicides, and cultivars with improved resistance. An understanding of the pathosystems and the inter-relationship
between host, pathogen and the environment is essential to be able to make correct decisions for disease control without compromising
the agronomic or economic ideal. For individual pathosystems, some components of the integrated management principles may
need to be given greater consideration than others. For instance, destruction of infested residue may be incompatible with
no or minimum tillage practices, or rotation intervals may need to be extended in environments that slow the speed of residue
decomposition. For ascochyta-susceptible chickpeas the use of disease-free seed, or seed treatments, is crucial as seed-borne
infection is highly effective as primary inoculum and epidemics develop rapidly from foci in favourable conditions. Implemented
fungicide strategies differ according to cultivar resistance and the control efficacy of fungicides, and the effectiveness
of genetic resistance varies according to seasonal conditions. Studies are being undertaken to develop advanced decision support
tools to assist growers in making more informed decisions regarding fungicide and agronomic practices for disease control. 相似文献
23.
Huimin Yang Murray Unkovich Ann McNeill Xianzhi Wang 《Biology and Fertility of Soils》2011,47(4):377-385
Symbiotic N2 fixation by lucerne (Medicago sativa) has capacity to provide significant inputs of N to agro-ecosystems, and the species has also been shown to scavenge soil mineral N and thus act as a sink for excess reactive N. The balance between these two N cycle processes was investigated in an extensive irrigated lucerne growing region where nitrate contamination of groundwater has been reported. We sampled 18 permanent pure lucerne stands under irrigation for standing dry matter, total shoot N, and N2 fixation using 15N natural abundance along with activity of the inducible enzyme nitrate reductase as indicators of use of soil NO3− by lucerne. On average 65% of lucerne N was obtained from symbiotic N2 fixation. Converting standing dry matter estimates to annual N2 fixation amounts we calculated average N2 fixation of 311 kg N/ha, including N in roots and nodules. Uptake of N from soil by lucerne was calculated to be 181 kg N/ha/year. We were not able to identify the source of this soil mineral N, although nitrate reductase activity of lucerne was higher than that of non-N2 fixing species examined. 相似文献
24.
Catia Pereira Itziar Aurora Montalbán Olatz García-Mendiguren Tomás Goicoa Maria Dolores Ugarte Sandra Correia Jorge Manuel Canhoto Paloma Moncaleán 《Journal of Forest Research》2016,21(3):143-150
Pinus halepensis has been described as a drought-tolerant species with high plasticity to growth in different environments. Its eco-physiological characteristics could facilitate the use of this species in large afforestations in the future scenery of climate change. Somatic embryogenesis is a biotechnological tool with potential for large-scale clonal propagation. In order to establish an improved regeneration protocol for Pinus halepensis, the effects of different temperatures (18, 23, and 28 °C) and water availability conditions (2, 3, and 4 g L?1 Gelrite®), during initiation of embryonal masses on the rate of initiation, proliferation, maturation, and the number of embryos developed, were evaluated. It was found that environmental conditions during the initiation stage of Pinus halepensis somatic embryogenesis influence the success of initiation and proliferation. In contrast, there was no effect of these conditions on the maturation rates and the number of somatic embryos. Somatic embryos were obtained in all treatments tested, indicating that plants can be produced from extreme conditions of induction, such as high temperatures (28 °C) and low water availability conditions (4 g L?1). 相似文献
25.
CX3CR1-mediated dendritic cell access to the intestinal lumen and bacterial clearance 总被引:3,自引:0,他引:3
Niess JH Brand S Gu X Landsman L Jung S McCormick BA Vyas JM Boes M Ploegh HL Fox JG Littman DR Reinecker HC 《Science (New York, N.Y.)》2005,307(5707):254-258
Dendritic cells (DCs) and macrophages are critical to innate and adaptive immunity to the intestinal bacterial microbiota. Here, we identify a myeloid-derived mucosal DC in mice, which populates the entire lamina propria of the small intestine. Lamina propria DCs were found to depend on the chemokine receptor CX3CR1 to form transepithelial dendrites, which enable the cells to directly sample luminal antigens. CX3CR1 was also found to control the clearance of entero-invasive pathogens by DCs. Thus, CX3CR1-dependent processes, which control host interactions of specialized DCs with commensal and pathogenic bacteria, may regulate immunological tolerance and inflammation. 相似文献
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Monica L. Bond Curtis M. Bradley Christian Kiffner Thomas A. Morrison Derek E. Lee 《Landscape Ecology》2017,32(8):1705-1721