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91.
Dusty L. McDonald Timothy H. Bonner Paul D. Cason Britt W. Bumguardner Shane Bonnot 《Journal Of Applied Aquaculture》2013,25(1):26-34
ABSTRACTTo determine the minimum age/size at which Southern Flounder, Paralichthys lethostigma, can safely be moved to outdoor rearing facilities in Texas, we examined survival of simulated temperature drops in two distinct life stages: premetamorphic larvae and two size classes of postmetamorphic juveniles (small = 9.8 ± 0.3 mm in TL; large = 19.7 ± 0.6 mm). Temperature was lowered by ?0.33°C/h to 4°C, 7°C, or 10°C, held for 48 h and then raised at +0.33°C/h back to normal rearing temperature. Fish were monitored daily for survival. Larger postmetamorphic flounder had high survival for all temperature treatments (89%–100% survival), whereas both premetamorphic larvae and smaller postmetamorphic juveniles had low survival (<30%) for all temperature treatments. 相似文献
92.
In this paper, we explore the entrepreneurial leadership strategies and routine work of actors located across a diverse array of organizational settings (i.e., farmers’ markets, community farms, community-supported agriculture programs, food and seed banks, local food print media) that combine to shape and sustain the Southern Arizona (AZ) local food system (LFS). We use the theoretical principles of institutional entrepreneurship and logic multiplicity to show how the strategies and routine work of local food actors at the organizational level combine to negotiate system-level meaning and structure within and across the Southern AZ LFS, which is an otherwise seemingly fragmented and contentious social space. We illustrate how the entrepreneurial work performed within multiple organizations and organizational types converge to form a hybrid (or blended) local food logic. Implications are discussed and recommendations for practice are proposed. 相似文献
93.
Hussein Abdel-Haleem Jan Bowman Mike Giroux Vladimir Kanazin Hope Talbert Lisa Surber Tom Blake 《Euphytica》2010,172(3):405-418
Cultivated barley is the major livestock feed grain in the Northern Plains and Northwestern United States due to the fact
that its short growing season and limited rainfall limit the planting and production of corn. Starch and fiber content play
a significant role in feedlot performance of animals raised on barley feed. To study the underlying genetic locations and
mechanisms for these traits, a recombinant inbred line population was derived from a cross between the hulled barley cultivar
Valier and a hull-less Swiss landrace line, PI370970. Valier has a high acid detergent fiber content (ADF) and low starch
and protein while PI370970 contains low ADF and high starch and protein content. To detect associated QTLs, data were collected
and analyzed from irrigated and rain-fed environments. A total of 30 main effect QTLs and four epistatic QTLs were identified
which conditioned ADF, starch and protein content under rain-fed, irrigated and combined analyses. These QTLs were located
on chromosomes 2H, 3H, 5H, 6H and 7H. Major ADF and starch QTL were identified on chromosome 7H near the nud locus (the locus controlling hulled vs. hull-less caryopsis). High heritability estimates for both ADF and starch content
suggest that early selection for these traits during breeding would be productive. Low ADF-QTL were independently verified
in a second population in a different genetic background. 相似文献
94.
Hussein Abdel-Haleem Jan G. P. Bowman Vladimir Kanazin Lisa Surber Hope Talbert Patrick M. Hayes Tom Blake 《Euphytica》2010,172(3):419-433
More than half of the barley grown in the USA is used for livestock feed, with the remaining stocks diverted for human food
and malting purposes. The use of barley grain as a major source of cattle feed has been criticized because of its rapid digestion
in the rumen, which can result in digestive disorders in cattle. In sacco dry matter digestibility (ISDMD) and particle size
(PS) after dry rolling have been found to play a role in the feedlot performance of barley as a feed grain. Reducing the rate
of ISDMD is predicted to result in significantly improved animal health and average daily gain. A recombinant inbred line
population derived from a cross between a high ISDMD, two-rowed barley cultivar (Valier) and a six-rowed Swiss landrace line
(PI370970) exhibiting far slower ISDMD has been developed for studying the underlying genetic locations and mechanisms of
these traits. To detect associated quantitative trait loci (QTLs), we collected and analyzed data from irrigated and rain-fed
environments. A significant negative correlation was observed between ISDMD and PS. High heritability estimates for ISDMD
and PS suggest that early selection for these traits during breeding would be achievable. Four QTLs were identified on chromosomes
2H, 6H, and 7H, explaining 73–85% of ISDMD phenotypic variation, while three QTLs on 2H and 7H were associated with variation
in PS and explained 58–77% of its variation. A major QTL on chromosome 2H tightly linked to the morphology-modifying gene
vrs1 was found to dramatically control 35–62% of the phenotypic variation of ISDMD and 26–53% of that of PS. The impact of the
vrs1 locus on ISDMD was validated in two populations representing different genetic backgrounds. Our results suggest that it may
also be advantageous to simultaneously overlap these QTLs around the vrs1 locus. 相似文献
95.
Hormones within the somatotropin cascade influence several physiological traits, including growth and reproduction. Active immunization against growth hormone-releasing factor (GRFi) initiated at 3 or 6 mo of age decreased weight gain, increased deposition of fat, and delayed puberty in heifers. Two experiments were conducted to investigate the effects of GRFi on puberty and subsequent ovulation rate in gilts. Crossbred gilts were actively immunized against GRF-(1-29)-(Gly)2-Cys-NH2 conjugated to human serum albumin (GRFi) or against human serum albumin alone (HSAi). In Exp. 1, gilts were immunized against GRF (n = 12) or HSA (n = 12) at 92 +/- 1 d of age. At 191 d of age, antibody titers against GRF were greater (P < .05) in GRFi (55.5 +/- 1.3%) than in HSAi (.4 +/- 2%) gilts. The GRFi decreased (P < .05) BW (86 +/- 3 vs 104 +/- 3 kg) by 181 d of age and increased (P < .05) backfat depth (15.7 +/- .4 vs 14.8 +/- .4 mm) by 130 d of age. At 181 d of age, GRFi reduced the frequency of ST release (1.0 +/- .5 vs 5.0 +/- .5, peaks/24 h; P < .0001) and decreased (P < .01) ST (1.1 +/- .06 vs 1.7 +/- .06 ng/mL), IGF-I (29 +/- 2 vs 107 +/- 2 ng/mL), and insulin concentrations (3.5 +/- .2 vs 6.3 +/- .2 ng/mL). The GRFi decreased (P < .05) feed conversion efficiency but did not alter age at puberty (GRFi = 199 +/- 5 d vs HSAi = 202 +/- 5 d) or ovulation rate after second estrus (GRFi = 10.7 +/- .4 vs HSAi = 11.8 +/- .5). In Exp. 2, gilts were immunized against GRF (n = 35) or HSA (n = 35) at 35 +/- 1 d of age. The GRFi at 35 d of age did not alter the number of surface follicles or uterine weight between 93 and 102 d of age, but GRFi decreased (P < .05) ovarian weight (.41 +/- .08 vs 1.58 +/- .4 g) and uterine length (17.2 +/- 1.1 vs 25.3 +/- 2.3 cm). Immunization against GRF reduced (P < .05) serum IGF-I (GRFi = 50 +/- 4 vs HSAi = 137 +/- 4 ng/mL) and BW (GRFi = 71 +/- 3 vs HSAi = 105 +/- 3 kg) and increased (P < .05) backfat depth (GRFi = .38 +/- .03 vs HSAi = .25 +/- .02 mm/kg). Age at puberty was similar in GRFi and HSAi gilts, but ovulation rate was lower (P < .05) after third estrus in GRFi (11.3 +/- .8) than in HSAi (13.8 +/- .8) gilts. Thus, GRFi at 92 or 35 d of age decreased serum ST, IGF-I, and BW in prepubertal gilts without altering age of puberty. However, GRFi at 35 d of age, but not 92 d of age, decreased ovulation rate. These results indicate that alterations in the somatotropic axis at 1 mo of age can influence reproductive development in pubertal gilts. 相似文献
96.
S S Trostle R T O'Brien J Britt K R Waller 《Journal of the American Veterinary Medical Association》1999,215(3):366-368
OBJECTIVE: To determine whether exogenous isobutane gas infused into the udders of dairy cattle could be detected ultrasonographically, and if so, what effects volume of gas infused and infusion pressure had on how long after infusion exogenous isobutane gas could be detected. DESIGN: Randomized block design. ANIMALS: 8 Holstein cows 28 to 32 days after parturition. PROCEDURE: In each cow, 1 mammary gland was not treated and the other 3 received 1 of 3 treatments by means of intramammary infusion: low volume-high pressure, low volume-low pressure, and high volume-high pressure infusion of isobutane gas. Mammary glands were examined ultrasonographically 1 hour before and 1, 3, 12, 24, 36, 48, 72, and 96 hours after treatment. RESULTS: After intramammary infusion of isobutane gas, bright echoes and associated acoustic shadows were seen ultrasonographically; echoes were no longer seen 72 hours after gas infusion. Percentages of mammary glands in which bright echoes were detected were not significantly different among the 3 treatment groups at any time during the study. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that exogenous isobutane gas infused into the mammary glands to enhance the appearance of the udder of show dairy cattle can be readily detected by ultrasonography. 相似文献
97.
Inferring spatial structure from population genetics and spatial synchrony in demography of Baltic Sea fishes: implications for management 下载免费PDF全文
Örjan Östman Jens Olsson Johan Dannewitz Stefan Palm Ann‐Britt Florin 《Fish and Fisheries》2017,18(2):324-339
The spatial structure of species is important for their dynamics and evolution, but also for management and conservation. There are numerous ways of inferring spatial structures, and information from multiple methods is becoming more common to examine how different processes shape the spatial structures of species to improve fish management. Here, we investigate the spatial structure of a suite of Baltic Sea fish species based on the following: (i) spatial (presumably neutral) genetic differentiation, reviewed from the literature, and (ii) spatial synchrony in abundance changes from time series of fishery‐independent surveys, which we currently find to be underused given the amount of data available. For each of these two methods, species were classified as having a distinct, continuous or no/weak spatial structure. In addition, based on each source of information, we estimated the spatial scale of management units for species. The results show that only among species confined to the coastal zone the two sources of information yielded a congruence of the spatial structure (displaying a continuous spatial structure). In contrast, offshore species show weak spatial genetic structure but stronger spatial structure of synchrony in abundance. Based on this, we suggest that population genetic structure and synchrony in abundance should be used as complementary information as they reflect different spatial processes and suggest that management actions should differ with respect to scale depending on the management targets applied. We propose similar analysis should be applied to areas outside the Baltic Sea, and other stock identification methods, to improve management of fish resources. 相似文献
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