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71.
Compressed wooden plates and dowels were used to connect members in post-and-beam structures as a substitute for a steel fastener.
In order to take advantage of the characteristic properties of compressed wood and to achieve optimum joint performance, two
compressed wooden plates were used in each joint to give multiple shear planes for each compressed wooden dowel. Consequently,
this type of joint showed very good properties in pull-out and momen-trotation performance, and its engineering design could
be further optimized. This joint is expected to be introduced to many kinds of structural systems, including long-span frame
structures made of domestic timber found in Japanese residential houses. 相似文献
72.
In Seong Choi Seung Gon Wi Se Ra Jung Darshan H. Patel Hyeun-Jong Bae 《Journal of Wood Science》2009,55(5):329-334
β-Glucosidase (β-1,4-D-glucoside glucohydrolase: EC.3.2.1.21) catalyzes the hydrolysis of β-glucosidic bonds between saccharides
and aryl or alkyl groups. A gene encoding β-glucosidase from Bacillus licheniformis KCTC 1918, an anaerobic spore-forming soil bacterium, was cloned and characterized. The structural gene for the β-glucosidase
consists of 1410 bp encoding 469 amino acid residues, and has a molecular weight of 53.4 kDa as estimated by sodium dodecyl
sulfate polyacrylamide gel electrophoresis with 12% separating gel. The enzyme activity was determined against pNPG as a substrate. The enzyme was optimally active at pH 6.0 (citrate-phosphate buffer) and 47°C. β-Glucosidase retained
100% of its original activity for 24 h. The activity of the enzyme was stimulated by glycerol and urea and was decreased by
Ca2+, Cu2+, Hg2+, Mg2+, and Mn2+. In particular, Cu2+ had the strongest negative effect on β-glucosidase activity. The purified β-glucosidase was active against pNPG and cellobiose. When the β-glucosidase was tested for cellulose hydrolysis, the supplement of β-glucosidase with cellulose
increased the glucose yield from pine wood powder by 139.8%. 相似文献
73.
During the monitoring of the mycological complex on different forest tree species in the Biogradska Gora National Park in north‐east Montenegro, symptoms indicative of ash dieback caused by Hymenoscyphus fraxineus were observed on young Fraxinus excelsior trees in the protected virgin forest, including dieback of plants and branches, wilting of leaves and shoots leading to a “flag‐like” habitus, premature shedding of leaves and longitudinal bark necroses. Using standard isolation methods, slow‐growing cultures with numerous phialides, typical of the asexual phase of the ash dieback fungus, were obtained. In addition, petioles with numerous characteristic apothecia were also recorded. This is the first report of H. fraxineus on common ash in Montenegro. Possible pathways of introduction and implications of the findings are discussed. 相似文献
74.
Cherry laurel (Prunus laurocerasus) is a native plant species in Serbian forests, but is also widely used for ornamental plantings. Following two extremely wet summers in 2014 and 2015, in spring and summer of 2016 and 2017, numerous cherry laurel plants with symptoms indicative for Phytophthora diseases, like wilting and chlorosis of leaves, dieback and bleeding bark necroses, were recorded in a park in Belgrade and in two ornamental nurseries in central Serbia. From necrotic bark samples and rhizosphere soil, self‐sterile Phytophthora isolates with woolly colonies were obtained. Due to the production of ellipsoid and elongated, non‐papillate sporangia in water and of ornamented oogonia with two‐celled antheridia in mating tests with tester strains of both Phytophthora × cambivora and P. cryptogea, these isolates were identified as P. ×cambivora which was confirmed by ITS sequence analysis. Pathogenicity of P. ×cambivora from cherry laurel (PCCL) was tested by inoculating one‐year‐old seedlings of cherry laurel under the bark. P. ×cambivora from European beech (PCB), and isolates of P. cactorum (CAC), P. cryptogea (CRY), P. plurivora (PLU) and P. ×serendipita (SER) were included as comparison. Three and a half months after inoculation, nine of the twelve plants in PCB, three in PCCL and CAC and two in PLU declined with longitudinal necroses and chlorosis, wilting and premature shedding of leaves. These results demonstrate the ability of P. ×cambivora to infect and cause decline of cherry laurel plants. The particularly high aggressiveness of the P. ×cambivora isolate from beech shows that this pathogen poses a serious risk to cherry laurel in the rare natural communities of cherry laurel and beech in Serbia. 相似文献
75.
76.
This study established a prediction model for bending properties of glued-laminated timber (glulam) using optimized knot and
modulus of elasticity (MOE) distributions of lumber laminate as the main input variables. For this purpose, knot and MOE data
were investigated for all pieces of lumber that were prepared for glulam manufacturing, and statistical distributions of knot
size, knot number in one lumber, and MOE of each laminate were optimized as distribution functions. These knot and MOE data
were used as input variables in the prediction model for bending properties, and were also used in generating virtual glulam
using the inverse transform method. Prediction of bending properties for glulam was carried out using the transformed section
method, which is partially provided in ASTM D 3737 (Annex A4). Predicted values were compared with those from full-scale four-point
bending tests for 60 six-layered glulams with 10 different laminar combinations. Finally, the allowable bending properties
of glulam for each specific laminate combination were determined by calculating the fifth percentile of the modulus of rupture
and the average modulus of elasticity from virtual test results of more than 1000 virtual glulams. From the results of this
study, predicted bending properties for glulam and their distributions could be used for structural design in both allowable
stress design and limit state design. 相似文献
77.
Changes in flavor release and aroma characteristics in a medium including food phenolics may be attributed to an intermolecular interaction between flavor compounds and phenolics. To investigate the interaction, one- and two-dimensional NMR studies have been carried out on the binding of two phenolics, gallic acid and naringin, with three aroma compounds, 2-methylpyrazine, vanillin, and ethyl benzoate. Evaluation of thermodynamic parameters and intermolecular nuclear Overhauser effects reveals that gallic acid can interact more strongly with aromatic flavors than naringin. The supramolecular complexation is also dependent on the structural nature of the flavors, with 2-methylpyrazine and vanillin interacting more strongly than ethyl benzoate. The interaction is principally pi-pi stacking between the galloyl ring and the aromatic ring of the aroma compounds, but secondary hydrogen-bonding effects help to stabilize the complex and enhance the specificity. 相似文献
78.
Methylation methods for the quantitative analysis of conjugated linoleic acid (CLA) isomers in various lipid samples 总被引:8,自引:0,他引:8
Park SJ Park CW Kim SJ Kim JK Kim YR Park KA Kim JO Ha YL 《Journal of agricultural and food chemistry》2002,50(5):989-996
Precise methylation methods for various chemical forms of conjugated linoleic acid (CLA), which minimize the formation of t,t isomers and allylmethoxy derivatives (AMD) with the completion of methylation, were developed using a 50 mg lipid sample, 3 mL of 1.0 N H(2)SO(4)/methanol, and/or 3 mL of 20% tetramethylguanidine (TMG)/methanol solution(s). Free CLA (FCLA) was methylated with 1.0 N H(2)SO(4)/methanol (55 degrees C, 5 min). CLA esterified in safflower oil (CLA-SO) was methylated with 20% TMG/methanol (100 degrees C, 5 min), whereas CLA esterified in phospholipid (CLA-PL) was methylated with 20% TMG/methanol (100 degrees C, 10 min), followed by an additional reaction with 1.0 N H(2)SO(4)/methanol (55 degrees C, 5 min). Similarly, CLA esterified in egg yolk lipid (CLA-EYL) was methylated by base hydrolysis, followed by reaction with 1.0 N H(2)SO(4)/methanol (55 degrees C, 5 min). These results suggest that for the quantitative analysis of CLA in lipid samples by GC, proper methylation methods should be chosen on the basis of the chemical forms of CLA in samples. 相似文献
79.
Lee KT Choi J Jung WT Nam JH Jung HJ Park HJ 《Journal of agricultural and food chemistry》2002,50(15):4190-4193
We isolated a new saponin named codonoposide (1) from the roots of Codonopsis lanceolata (Campanulaceae) and characterized it as 3-O-[beta-D-xylopyranosyl(1-3)-beta-D-glucuronopyranosyl]-3beta,16alpha-dihydroxyolean-28-oic acid 28-O-[beta-D-xylopyranosyl (1-3)-alpha-L-rhamnopyranosyl (1-2)-alpha-L-arabinopyranosyl] ester by chemical, physicochemical, and 2DNMR techniques. Complete hydrolysis of 1 produced a sapogenin (1a), and the partial hydrolysis and further isolation afforded two prosapogenins (1b, 1c). The structures of 1a, 1b, and 1c were found to be 3beta,16alpha-dihydroxyolean-28-oic acid (echinocystic acid, 1a), 3-O-beta-D-glucuronopyranoside of 1a, and 3-O-beta-D-xylopyranosyl (1-3)-beta-D-glucuronopyranoside of 1a, respectively, on the basis of spectroscopic data. On MTT assay, 1a showed marginal cytotoxic activity whereas 1b exhibited more cytotoxicity than 1a. However, the bisdesmosylsaponin 1 exhibited no cytotoxicity (IC(50)>0.3 mM against tested cell lines). This result indicated that glycoside linkage of glucuronic acid at C-3 enhances the cytotoxicity of sapogenin (1a), and additive glycosylation of xylose to 1b strongly enhances the cytotoxicity of 3-O-monosaccharides (1b). Therefore, true forms of codonoposide for the cytotoxicity must be sapogenins or prosapogenins. 相似文献
80.
The effects of feeding chemically treated dietary supplements (CTDS) containing sunflower oil and dl-alpha-tocopheryl acetate (TA) on alpha-tocopherol content and fatty acid profile in edible tissues of lambs were estimated. Compared with lambs fed control diet (CD), lambs fed CD plus 250 IU of either TA or CTDS increased serum alpha-tocopherol. The CTDS-fed lambs further increased serum alpha-tocopherol by 29% over those fed CD plus 250 IU of TA. Lambs supplemented with TA or CTDS increased alpha-tocopherol in muscle and adipose tissues as compared with lambs fed CD. The CTDS-fed lambs had higher levels of alpha-tocopherol in gluteus medius (7.55 vs 6.05 mug/g), psoas major (7.43 vs 6.02 mug/g), and subcutaneous fat (12.6 vs 9.98 mug/g) compared with the TA-fed lambs. Feeding lambs CTDS also substantially increased levels of linoleic acid in the adipose tissues while decreasing the content of palmitic and oleic acids. 相似文献