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51.
This research note offers a brief summary of recent cartographic work in the province of Lao Cai in northern Vietnam, with a specific focus on the districts of Sa Pa and Bac Ha. By providing a representation of topography in digital format, which enables a connection between demographic and physical variables, the long term aim is to illustrate the relationship between ethnicity and topography.  相似文献   
52.
滴灌条件下枯草芽胞杆菌S37和S44对棉花黄萎病的防治效果   总被引:1,自引:0,他引:1  
采用拌种和随水滴施2次的方法测定了2株芽胞杆菌对棉花黄萎病的防治效果。结果表明,在滴灌条件下2株枯草芽胞杆菌对棉花黄萎病均表现出较好的防治作用,在小区试验中,S37和S44对棉花黄萎病的防治效果分别为29.86%和42.81%,产量分别增加了25.22%和34.73%。在田间试验中,S37在143团和147团的防病效果分别为51.3%和55.1%,增产效果分别达到7.43%和17.62%,S44在143团和147团的防病效果分别为35.2%和39.3%,增产效果分别达到5.56%和15.51%。  相似文献   
53.
咸水资源农业灌溉应用研究进展与展望   总被引:11,自引:1,他引:11  
灌溉水资源的短缺已成为干旱半干旱地区农业持续发展的一个重要限制因素,咸水资源的开发利用可有效的解决灌溉水源短缺的问题。从咸水灌溉对作物、生态环境的影响、咸水灌溉技术以及咸水灌溉条件下的改良等方面总结了国内外咸水资源灌溉利用的研究进展,为合理的利用咸水资源进行灌溉提供指导。从咸水资源灌溉利用现状来看,膜下滴灌为干旱半干旱地区有效的利用咸水和微咸水资源以及盐碱地的开发利用提供了有效的手段。但利用膜下滴灌方式进行咸水灌溉,目前仍存在一些问题,需要进一步研究。此外,如何从流域或区域尺度上评价咸水灌溉的影响,并从更大尺度维持盐分平衡及环境的可持续发展值得深入研究。  相似文献   
54.
土壤生态系统服务的概念、量化及其对城市化的响应   总被引:5,自引:1,他引:5  
土壤生态系统是陆地生态系统的重要组成部分,是人类赖以生存的重要资源。全球的快速城市化进程使土壤生态系统服务发生了部分不可逆转的变化。本文归纳了土壤生态系统服务定义和分类的发展过程,介绍了土壤生态系统服务定量化表征方法以及GUMBO、In VEST等几种常用的评价模型,并从供给服务、调节服务、文化服务和支持服务几个方面阐述土壤生态系统服务对城市化的响应。针对土壤生态系统服务分类、建模、空间表达以及其对人为活动的响应等方面研究存在的不足,本文提出未来的研究重点方向:建立土壤生态系统服务分类体系与标准,构建基于生态过程的土壤生态系统服务量化模型,开展土壤生态系统服务制图与权衡研究,加强土壤生态系统服务对城市化的动态响应机制与过程研究。期望更多的人关注和参与土壤生态系统服务研究,并将其应用于土壤资源管理、生态文明建设等政府决策。  相似文献   
55.
Volatile compounds were extracted by a pentane/ether (1:1) mixture from the leaves of seven citrus somatic tetraploid hybrids sharing mandarin as their common parent and having lime, Eurêka lemon, lac lemon, sweet orange, grapefruit, kumquat, or poncirus as the other parent. Extracts were examined by GC-MS and compared with those of their respective parents. All hybrids were like their mandarin parent, and unlike their nonmandarin parents, in being unable to synthesize monoterpene aldehydes and alcohols. The hybrids did retain the ability, although strongly reduced, of their nonmandarin parents to synthesize sesquiterpene hydrocarbons, alcohols, and aldehydes. These results suggest that complex forms of dominance in the mandarin genome determine the biosynthesis pathways of volatile compounds in tetraploid hybrids. A down-regulation of the biosynthesis of methyl N-methylanthranilate, a mandarin-specific compound, originates from the genomes of the nonmandarin parents. Statistical analyses showed that all of the hybrids were similar to their common mandarin parent in the relative composition of their volatile compounds.  相似文献   
56.
Conservation: limits of land sparing   总被引:1,自引:0,他引:1  
  相似文献   
57.
为了探讨miR-202在鱼类胚胎发育中的功能,采用实时定量反转录PCR技术和整体原位杂交技术检测了miR-202在斑马鱼胚胎发育阶段的表达。结果发现miR-202是母源性分子并在斑马鱼胚胎发育过程中持续表达,尤其在早期胚胎发育阶段表达水平较高。在此基础上,采用基因沉默技术在斑马鱼受精卵中显微注射miR-202的反义锁核苷酸,实时荧光定量反转录PCR技术和整体原位杂交技术结果显示miR-202反义锁核苷酸可以显著下调斑马鱼胚胎中miR-202表达水平,同时发现反义抑制miR-202后胚胎发育停滞在4 hpf时左右。共同注射miR-202前体可以部分挽救反义抑制miR-202后导致的胚胎发育停滞。本研究证明miR-202在斑马鱼胚胎发育过程中起着重要的调控作用,其功能是斑马鱼胚胎早期发育所必需的。为进一步探索miR-202在鱼类胚胎发育过程的功能奠定了基础。  相似文献   
58.
Wood production represents a large but variable fraction of gross primary production (GPP) in highly productive Eucalyptus plantations. Assessing patterns of carbon (C) partitioning (C flux as a fraction of GPP) between above- and belowground components is essential to understand mechanisms driving the C budget of these plantations. Better knowledge of fluxes and partitioning to woody and non-woody tissues in response to site characteristics and resource availability could provide opportunities to increase forest productivity. Our study aimed at investigating how C allocation varied within one apparently homogeneous 90 ha stand of Eucalyptus grandis (W. Hill ex Maiden) in Southeastern Brazil. We assessed annual above-ground net primary production (ANPP: stem, leaf, and branch production) and total belowground C flux (TBCF: the sum of root production and respiration and mycorrhizal production and respiration), GPP (computed as the sum of ANPP, TBCF and estimated aboveground respiration) on 12 plots representing the gradient of productivity found within the stand. The spatial heterogeneity of topography and associated soil attributes across the stand likely explained this fertility gradient. Component fluxes of GPP and C partitioning were found to vary among plots. Stem NPP ranged from 554 g C m(-2) year(-1) on the plot with lowest GPP to 923 g C m(-2) year(-1) on the plot with highest GPP. Total belowground carbon flux ranged from 497 to 1235 g C m(-2) year(-1) and showed no relationship with ANPP or GPP. Carbon partitioning to stem NPP increased from 0.19 to 0.23, showing a positive trend of increase with GPP (R(2) = 0.29, P = 0.07). Variations in stem wood production across the gradient of productivity observed at our experimental site were a result of the variability in C partitioning to different forest system components.  相似文献   
59.
Any apparatus that restricts a horse’s movement can compromise welfare. Eye temperature as measured remotely using infrared thermography is emerging as a correlate of salivary cortisol concentrations in horses. This article explores the effect on the temperature of the eyes and facial skin of horses wearing devices that restrict jaw movements. In certain equestrian disciplines, unacceptable equine oral activity, such as gaping of the mouth, is penalized because it reflects poor training and lack of compliance. This explains the wide range of nosebands and flash straps designed to prevent the mouth opening. Some of these nosebands are banned from higher-level dressage competitions in which double bridles are mandatory, possibly because they are regarded as restrictive. Nevertheless, the current international rules overlook the possibility that noseband can appear innocuous even though some designs, such as the so-called crank noseband, can be ratcheted shut to clamp the jaws together. Some equestrian manuals and competition rule books propose that “two-fingers” be used as a spacer to guard against overtightening of nosebands but fail to specify where this gauge should be applied. The vagueness of this directive prompted us to undertake a small random survey of the finger dimensions of adult men (n = 10) and women (n = 10). There were significant sex differences in the measurements of fingers of adults (P < 0.001), thus illustrating that the “two-finger rule” is not a reliable guide for standardized noseband fastening. Infrared thermography was used to measure the temperature of facial skin and eyes of adult horses (n = 5) wearing a double bridle with and without a cavesson noseband. A taper gauge was developed based on the mean circumference of adult index and middle fingers (9.89 ± 0.21 cm), and this was used as a spacer at the nasal planum or beside the mandible when tightening the noseband. The nosebands were fastened significantly tighter when the taper gauge was used beside the mandible than at the nasal planum (P = 0.02). Wearing double bridles and nosebands that had been tightened with and without the taper gauge caused an increase in eye temperature compared with baseline values (P = 0.012), and the tighter the noseband was fastened, the cooler the facial skin of the horse (and, presumably, the greater the impairment of vascular perfusion) when compared with baseline values (P = 0.016). This study suggests that horses wearing double bridles and tight nosebands undergo a physiological stress response and may have compromised vascular perfusion. Consequently, on welfare grounds, the use of nosebands that cause any constriction of jaw movement should be reviewed as soon as possible.  相似文献   
60.
Biochars, derived from rambutan (Nepheliumlappaceum) peel through slow pyrolysis, were characterised and investigated as potential adsorbent for the removal of copper ion, Cu(II) from aqueous solution. Characteristics of five biochars of rambutan peel with different pyrolytic temperatures ranging from 300 to 700 °C (B300, B400, B500, B600, B700) were studied, and adsorption abilities of respective biochars were evaluated. Adsorption experiments were carried out by varying adsorbent dosage (0.2, 0.4, 0.8, 1.0, 2.0, and 4.0 g/L) and initial copper ion, Cu(II) concentrations (50 and 100 mg/L) to determine the optimum pyrolytic temperature of biochar with high adsorption affinity. The adsorption kinetics were best described by the pseudo-second order model for all the tested biochars, while the adsorption equilibrium best fitted by Langmuir isotherm. The overall results showed that biochar derived at 600 °C can be used as an effective adsorbent for removal of Cu(II) from aqueous solutions. Furthermore, feedforward artificial neural network (FFBP) modelling was performed to compare the simulated results with experimental output data of Thermogravimetric analysis (TGA) and atomic absorption spectroscopy (AAS) analysis which were trained using Levenberg-Marquardt (LM) backpropagation algorithm. The FFBP structure for pyrolysis process comprised of TGA temperature as input and biomass final weight as output. The adsorption modelling was simulated using adsorption time, temperature, biochar dosage and initial Cu(II) concentration as input data, while final Cu(II) concentration was used as output data to the network. Finally, modelling structure of 1-9-1 and 4-8-1 gave best performance with regression, R 2 value of 0.9999 and 0.9547 for TGA and AAS analysis, respectively.  相似文献   
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