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111.
Contributions of quisqualate and NMDA receptors to the induction and expression of LTP 总被引:18,自引:0,他引:18
The contributions of two subclasses of excitatory amino acid transmitter receptors to the induction and expression of long-term potentiation (LTP) were analyzed in hippocampal slices. The quisqualate/kainate receptor antagonist DNQX (6,7-dinitro-quinoxaline-2,3-dione) blocked 85% of the evoked field potential, leaving a small response that was sensitive to D-AP5 (D-2-amino-5-phosphonopentanoate), an N-methyl-D-aspartate (NMDA) receptor blocker. This residual D-AP5-sensitive response was of comparable size in control and previously potentiated inputs. High-frequency stimulation in the presence of DNQX did not result in the development of robust LTP. Washout of the drug, however, revealed the potentiation effect. Thus NMDA-mediated responses can induce, but are not greatly affected by, LTP; non-NMDA receptors, conversely, mediate responses that are not needed to elicit LTP but that are required for its expression. 相似文献
112.
Lunar Gravity over Large Craters from Apollo 12 Tracking Data 总被引:1,自引:0,他引:1
The Doppler residuals from the Apollo 12 lunar module radio tracking data indicate large negative accelerations over the craters Ptolemaeus and Albategnius. The mass deficienicies required to produce these accelerations are approximately equivalent to the removal of the surface material to a depth of 1 kilometer over the entire area of these craters. Several other features of the gravity fine structure can also be correlated with topography. 相似文献
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According to the Milankovitch theory, changes in the incident solar radiation, called insolation, in the Northern Hemisphere provide the driving force for global glacial cycles. In their Perspective, Karner and Muller discuss recent studies of corals from around the world that shed doubt on the applicability of the theory to the termination of the penultimate glaciation. The authors argue that a fresh, unbiased look at the data is warranted. 相似文献
115.
Uniaxial compression at 800 degrees C and 5 kilobars confining pressure of a specimen cored from a single crystal of orthoenstatite [(Mg,Fe)SiO(3)] produced fine lamellae 100 to 1000 angstroms thick of untwinned clinoenstatite. The two phases are joined along (100) planes and have b and c axes in common. The orientation of the clinoenstatite a axis contradicts several previously suggested transformation mechanisms and reduces the set of possible mechanisms by a factor of 2. 相似文献
116.
The age of a sample of carbon dioxide has been determined by accelerating the carbon with a cyclotron and detecting the carbon-14 ions in the beam. Nitrogen-14 was eliminated as a background through the use of a range-separation technique. To avoid all possibility of experimenter bias, the measurement was conducted in a blind fashion. 相似文献
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Arora H Du P Tan KW Hyun JK Grazul J Xin HL Muller DA Thompson MO Wiesner U 《Science (New York, N.Y.)》2010,330(6001):214-219
Epitaxy is a widely used method to grow high-quality crystals. One of the key challenges in the field of inorganic solids is the development of epitaxial single-crystal nanostructures. We describe their formation from block copolymer self-assembly-directed nanoporous templates on single-crystal Si backfilled with Si or NiSi through a laser-induced transient melt process. Depending on thickness, template removal leaves either an array of nanopillars or porous nanostructures behind. For stoichiometric NiSi deposition, the template pores provide confinement, enabling heteroepitaxial growth. Irradiation through a mask provides access to hierarchically structured materials. These results on etchable and non-etchable materials suggest a general strategy for growing epitaxial single-crystal nanostructured thin films for fundamental studies and a wide variety of applications, including energy conversion and storage. 相似文献
120.
van Galen G Saegerman C Marcillaud Pitel C Patarin F Amory H Baily JD Cassart D Gerber V Hahn C Harris P Keen JA Kirschvink N Lefere L McGorum B Muller JM Picavet MT Piercy RJ Roscher K Serteyn D Unger L van der Kolk JH van Loon G Verwilghen D Westermann CM Votion DM 《Equine veterinary journal》2012,44(5):621-625
Reasons for performing study: Appropriate management of atypical myopathy (AM) requires the establishment of an accurate diagnosis and prognosis. Furthermore, preventive measures to avoid AM need to be refined. Objectives: The aims of the study were as follows: 1) to improve the diagnosis of AM; 2) to identify prognostic predictors; and 3) to refine recommended preventive measures based on indicators of risk factors. Methods: An exploratory analysis of cases in Europe between 2006 and 2009 reported to the Atypical Myopathy Alert Group was conducted. Based on clinical data, reported cases were allocated into 2 groups: confirmed or highly probable AM (AM group; further divided into survivors and nonsurvivors); and cases with a low probability of having AM or with another final diagnosis (non‐AM group). Using Welch's test and odds ratios corrected for multiple comparisons, the AM vs. non‐AM groups were compared to identify indicators for diagnosis and risk factors, and survivors vs. nonsurvivors in the AM group were compared to identify prognostic factors. Sensitivity, specificity and positive and negative predictive values were calculated for specific clinical signs related to final diagnosis and outcome. Results: From 600 reported cases, 354 AM cases (survival rate of 26%) and 69 non‐AM cases were identified, while there were insufficient data to categorise the remainder. Variables valuable for diagnosing AM compared with similar diseases were as follows: presence of dead leaves and wood and/or trees on pastures; sloping pastures; full‐time pasture access; no food supplementation; normal body condition; pigmenturia; normothermia; and congested mucous membranes. Nonsurvival was associated with recumbency, sweating, anorexia, dyspnoea, tachypnoea and/or tachycardia. Survival was associated with remaining standing most of the time, normothermia, normal mucous membranes, defaecation and vitamin and antioxidant therapy. Conclusions and potential relevance: This study refines the list of risk factors for AM. Clinical signs valuable for diagnosis and prognosis have been identified, enabling clinicians to improve management of AM cases. 相似文献