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961.
Kevin C Williams Brian D Paterson Christopher G Barlow † Anne Ford & Robert Roberts 《Aquaculture Research》2003,34(1):33-42
The organoleptic quality of barramundi fed for 66 days on pelleted diets containing varying amounts of fish meal and meat meal was determined in two experiments (E1 and E2). Each compared four diets: a 430 g kg?1 crude protein (CP) control diet (containing 35% Chilean anchovy fish meal); two diets containing high inclusions (40% or more) of meat meal; and a proprietary barramundi diet. In E1, the two meat meal diets contained 10% Chilean fish meal whereas the two meat meal diets in E2 had no marine protein ingredients. Panellists identified and rated the colour of flesh, and scored odour, flavour and texture characteristics and overall liking on structured graphic line scales (0–100). Fish fed the high‐meat meal diets were sweeter and firmer than those fed the high‐fish meal control diet in E1 (P < 0.05). Scores for fishy flavour were also highest for the meat meal diets and lowest for the proprietary diet. In both E1 and E2, scores were high (> 60) for overall liking and low (< 10) for undesirable odours and tastes. Exclusion of all sources of marine protein from the diet in E2 did not detract from the sensory value of the fish. The influence of diet on the fatty acid profile of the fish was examined in E2. Compared with fish fed the control diet, the neutral lipid fraction of those fed the meat meal diets had higher proportions of saturated and short‐chain monounsaturated fatty acids at the expense of longer chain fatty acids, especially 22:6n‐3. Polar lipids showed only subtle dietary effects, which were confined to the long‐chain unsaturated fatty acids. 相似文献
962.
We investigated how stream fragmentation affects local fish species persistence and extinction from three Rio Grande systems (Texas, USA) stream reaches with different levels of natural fragmentation. We examined species–volume (SV) relationships of fish assemblages in 42 pools across the watersheds and predicted greater fragmentation would correspond to an increase in the slope of the SV relationship due to decreased within‐reach rescue effects. In addition, we examined relationships among tributary‐specific nested subset patterns, local habitat features and spatial position of the reaches relative to the Rio Grande mainstem to better understand the importance of local and regional processes on fish species richness patterns in the stream reaches. Slopes of the SV curves did not differ among the stream reaches, but the intercepts of the SV curves were significantly different. These results indicated rescue effects among habitats within a stream reach were not apparent; however, rescue effects from the mainstem largely determined the species richness of a given stream reach. The nested subset patterns in all stream reaches were related to several local environmental factors, and large, deep pools provided important aquatic refugia in all three systems. We suggest declines in mainstem and tributary flows will likely continue to impact local and regional fish assemblage attributes. High flow events are important for dispersal and can reset tributary fish communities for the next extinction‐driven, successional cycle. 相似文献
963.
964.
Brian M. Savory Christopher J. Hibbitt Anthony H. Catchpole 《Pest management science》1975,6(2):145-158
Outdoor pot experiments, carried out between 1967 and 1971, mainly with Polygonum lapathifolium L. and Stellaria media (L.) Vill., showed that herbicidal potency of ioxynil and bromoxynil salts and esters was affected by climatic conditions, particularly solar radiation and relative humidity. Multiple regression equations were frequently obtained which accounted for 80% or more of the observed variation in effective dose (ED90). By contrast, experiments in growth cabinets suggested that air temperature was the most important climatic variable; the reasons for this disagreement are discussed. It is concluded that climatic factors affect the potency of ioxynil and bromoxynil via their influence on leaf uptake; ester formulations (emulsions) were much less affected than aqueous salt solutions. 相似文献
965.
Christopher M. Pearce Tara L. Daggett Shawn M. C. Robinson 《Journal of the World Aquaculture Society》2002,33(3):268-277
Adult green sea urchins Strongylocentrotus droebachiensis were fed three different quantities (0.25, 0.50, 1.00% body weight/d) of a prepared feed during a 12‐wk experiment to determine the effect of food ration on gonad quantity and quality. A diet of kelp, Laminaria longicruris and/or L. digitata, fed at satiation (3% body weight/d) and urchins taken from the wild at the beginning and end of the experiment served as controls. Urchins fed prepared feed or kelp increased their percent gonad yield significantly over the experimental period. Affer 12 wk, individuals fed the prepared diet at 0.50 or 1.00% body weighffd had significantly higher percent gonad yields (mean ± SEM: 23.5 ± 0.6% and 23.4 ± 0.7%, respectively) than urchins fed at 0.25% body weight/d (18.0 ± 1.0%) or control animals given kelp (18.3 ± 0.8%). There was no significant difference in gonad yield between the 0.50 and 1.00% feeding levels. All feeding treatments had significantly higher percent gonad yields than urchins sampled from the wild at the end of the experiment that had recently spawned (2.8 ± 0.5%). There was no significant difference in gonad taste among urchins fed the prepared diet at 0.25% body weight/d, those given kelp, or those collected from the wild at the end of the experiment (good to very good ratings), but all of these treatments had significantly better tasting gonads than urchins given the prepared feed at 0.50 or 1.00% body weight/d (satisfactory ratings). Gonad taste rating of urchins fed a prepared diet was dependent on ration with greater feed amounts leading to worse tasting gonads (linear regression: r2= 0.68, P < 0.01). Gonad color, texture, and firmness did not differ significantly among any of the feed ration treatments or kelp control. Results suggest that the best ration for prepared feed would be 0.50% body weightld since this would optimize gonad yield while minimizing feed costs. Further research on prepared feeds is required to optimize both gonad color and taste. 相似文献
966.
967.
968.
969.
ULTRASONOGRAPHIC DIAGNOSIS OF CONGENITAL PORTOSYSTEMIC SHUNTS IN DOGS: RESULTS OF A PROSPECTIVE STUDY 总被引:2,自引:0,他引:2
The aims of this study were to determine if accurate diagnosis of congenital portosystemic shunt was possible using two dimensional, grey-scale ultrasonography, duplex-Doppler, and color-flow Doppler ultrasonography in combination, and to determine if dogs with congenital portosystemic shunts have increased or variable mean portal blood flow velocity. Eighty-two dogs with clinical and/or clinicopathologic signs compatible with portosystemic shunting were examined prospectively. Diagnosis of congenital portosystemic shunt was subsequently confirmed in 38 of these dogs using operative mesenteric portography: 14(37%) dogs had an intrahepatic shunt and 24(63%) had an extrahepatic shunt. Ultrasonography had a sensitivity of 95%, specificity of 98%, and accuracy of 94%. Ultrasonographic signs in dogs with congenital portosystemic shunts included small liver, reduced visibility of intrahepatic portal vessels, and anomalous blood vessel draining into the caudal vena cava. Correct determination of intra - versus extrahepatic shunt was made ultrasonographically in 35/38 (92%) dogs. Increased and/or variable portal blood flow velocity was present in 21/30 (70%) dogs with congenital portosystemic shunts. In one dog with an intrahepatic shunt the ultrasonographic diagnosis was based partly on finding increased mean portal blood flow velocity because the shunting vessel was not visible. Detection of the shunting vessel and placement of duplex-Doppler sample volumes were facilitated by use of color-flow Doppler. Two-dimensional, grey-scale ultrasonography alone is sufficient to detect most intrahepatic and extrahepatic shunts; sensitivity is increased by additional use of duplex-Doppler and color-flow Doppler. Increased and/or variable portal blood flow velocity occurs in the majority of dogs with congenital portosystemic shunts. 相似文献
970.
David F. Millie Oscar M. Schofield Christopher P. Dionigi Peter B. Johnsen 《Journal of the World Aquaculture Society》1995,26(4):329-345
Management practices in aquaculture systems contribute to maximum growth of phytoplankton, often resulting in extensive blooms of noxious cyanobacteria. Because periods of oxygen depletion and “off flavor” events correspond to intense algal growth and metabolic activity, accurate identification of algal dynamics and physiological state is important. Current efforts to assess algal assemblages rely upon microscopic evaluation; however, the incorporation of such evaluation into monitoring programs is limited due to the level of skill and training required, the excessive costs and time required to assess algal heterogeneity within/among aquaculture systems, and the lack of information provided concerning physiological state. The distinct biwptical characteristics of the blooms lend themselves to pigment-based methodologies (pigment and in vivo absorption “signatures”, chlorophyll a fluorescence, multi-spectral remote sensing) which complement microscopic evaluation and can be implemented into large-scale monitoring programs. For example, because the key ingredient for success of such programs is the rapid, reliable, and accurate characterization of algal biomass along variable temporal/spatial scales, remotely-sensed data acquisition most likely will be required. High-performance liquid chromatography (HPLC)-derived pigment and in vivo absorption “signatures” can delineate problematic algal phylogenetic groups and physiological states. Further, measurements of chlorophyll a fluorescence provide estimates of phytoplankton absorption, quantum efficiency, and potentially production potential and growth rate. As such, they can be used to confirm the systematic significance of remotely-sensed data. It would be highly desirable to integrate an evaluation program using bio-optical methodologies into a geographic information system to allow for integrating, modeling, and predicting parameters of management interest over the scales relevant to aquacultural and water resource management. 相似文献