全文获取类型
收费全文 | 308篇 |
免费 | 14篇 |
专业分类
林业 | 14篇 |
农学 | 1篇 |
基础科学 | 1篇 |
42篇 | |
综合类 | 16篇 |
农作物 | 11篇 |
水产渔业 | 28篇 |
畜牧兽医 | 186篇 |
园艺 | 10篇 |
植物保护 | 13篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 7篇 |
2021年 | 6篇 |
2020年 | 15篇 |
2019年 | 21篇 |
2018年 | 6篇 |
2017年 | 9篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 5篇 |
2013年 | 18篇 |
2012年 | 10篇 |
2011年 | 35篇 |
2010年 | 14篇 |
2009年 | 9篇 |
2008年 | 23篇 |
2007年 | 20篇 |
2006年 | 18篇 |
2005年 | 9篇 |
2004年 | 17篇 |
2003年 | 17篇 |
2002年 | 16篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
排序方式: 共有322条查询结果,搜索用时 15 毫秒
121.
Susan Bowers Scott Gandy Ken Paul Lisa Woods Denise D'Angelo Carolyn Horton Chris Tabaka Scott Willard 《Journal of zoo and wildlife medicine》2005,36(3):451-456
In this study, an attempt was made to use vaginal electrical impedance to predict calving in a female white rhinoceros (Ceratotherium simum simum) and to determine the relationship between vaginal electrical impedance and hormonal profiles during pregnancy. The principle behind vaginal electrical impedance is that a change in the ionic balance of vaginal and cervical mucus occurs in response to changes in reproductive hormones. Three times weekly vaginal electrical impedance readings and fecal samples were collected from midgestation to calving (a 6-mo period). The extracted fecal samples were analyzed for immunoreactive estrogens, progestagens, and corticoids by RIA. Vaginal electrical impedance readings did not decrease before calving but remained consistent throughout the last 140 days of pregnancy. Fecal progestagens in the white rhinoceros decreased between day 17 and day 1 before calving, whereas estrogens increased between 4 and 2 mo before calving, with an additional increase occurring 1 mo before calving. Fecal corticoids increased 5 mo before calving, slowly declined, and increased again within 3 wk before calving. A decline in vaginal electrical impedance was noted 168 days before calving and remained at low levels for 4 wk. At the time of this decrease, the female became aggressive toward the male and began lactating. Fecal progestagens and estrogens did not change during this time; however, fecal corticoids increased as vaginal electrical impedance readings returned to normal along with her behavior and cessation of lactation. In summary, the use of vaginal electrical impedance could not predict parturition in the white rhinoceros. However, an anomaly occurred during pregnancy that was supported by vaginal electrical impedance readings, a change in female behavior, premature lactation, and a subsequent increase in fecal corticoids. The etiology of this physiological anomaly is unknown, yet it did not compromise pregnancy. 相似文献
122.
Wess G Thomas WP Berger DM Kittleson MD 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2006,20(4):877-884
We reviewed the indications for age and breeds of dogs who received transvenous endocardial artificial pacemaker (AP) implantation (n = 105) and complications and survival thereafter at a single institution over a 6-year period. A third-degree atrioventricular (AV) block (59%) and sick sinus syndrome (SSS; 27%) were the most common indications, along with a high-grade second-degree AV block (9%) and atrial standstill (5%). The most common breeds identified were Labrador Retriever (n = 16; 11 with a third-degree AV block), American Cocker Spaniel (n = 14; 10 with SSS), and Miniature Schnauzer (n = 13; all with SSS). Common presenting complaints were syncope (n = 66) and exercise intolerance or lethargy (n = 25). Half of the dogs (n = 52) had a history of acute onset of clinical signs (<2 weeks). Mean survival time for the 60 dogs who died during the study period was 2.2 years (range, 0.1-5.8 years). Major complications occurred in 13% of dogs and included lead displacement (n = 7), sensing problems that led to syncope (n = 3), infection at the pacemaker site (n = 1), bleeding (n = 1), and ventricular fibrillation during implantation (n = 1; successfully defibrillated). Minor complications occurred in 11 dogs (11%). The success rate of transvenous AP implantation was comparatively high (all dogs survived the first 48 hours), and the complication rate was comparatively low when compared with a previous multicenter study, most likely because of how commonly the procedure was performed and supervisory experience. 相似文献
123.
Denise M. Lindley BS DVM John T. Hathcock DVM MS William W. Miller DVM MS M. Nina DiPinto VMD 《Veterinary radiology & ultrasound》1988,29(5):209-212
Following head trauma, the left globe of a Red Tail Hawk showed demonstrable indentation on palpation. Recurrent anterior chamber collapse and reformation dependent on head position was the most significant clinical finding. A fracture of the scleral ossicles in the caudal portion of the scleral ring was identified in the rostrocaudal radiograph of the skull. Conservative management of the fracture resulted in phthisis bulbi. Fractured scleral ossicles have been shown radiographically in the enucleated globe but have not been previously demonstrated in the eye of the living bird. 相似文献
124.
Thomas A. Spies Thomas W. Giesen Frederick J. Swanson Jerry F. Franklin Denise Lach K. Norman Johnson 《Landscape Ecology》2010,25(8):1185-1199
Conserving biological diversity in a changing climate poses major challenges for land managers and society. Effective adaptive
strategies for dealing with climate change require a socio-ecological systems perspective. We highlight some of the projected
ecological responses to climate change in the Pacific Northwest, U.S.A and identify possible adaptive actions that federal
forest managers could take. The forest landscape, ownership patterns and recent shift toward ecologically based forest management
provide a good starting place for conserving biological diversity under climate change. Nevertheless, undesirable changes
in species and ecosystems will occur and a number of adaptive actions could be undertaken to lessen the effects of climate
change on forest ecosystems. These include: manipulation of stand and landscape structure to increase ecological resistance
and resilience; movement of species and genotypes; and engaging in regional, multi-ownership planning to make adaptive actions
more effective. Although the language and goals of environmental laws and policies were developed under the assumption of
stable climate and disturbance regimes, they appear to be flexible enough to accommodate many adaptive actions. It is less
certain, however, if sufficient social license and economic capacity exist to undertake these actions. Given the history of
contentious and litigious debate about federal forest management in this region, it is likely that some of these actions will
be seen as double-edge swords, spurring social resistance, especially where actions involve cutting trees. Given uncertainties
and complexity, collaborative efforts that promote learning (e.g. adaptive management groups) must be rejuvenated and expanded. 相似文献
125.
Genhua Niu Denise S. Rodriguez Evan Call Paul W. Bosland April Ulery Erik Acosta 《Scientia Horticulturae》2010
Salt tolerance of five cultivars of Capsicum annuum L. Early Jalapeno, Golden Treasure, NuMex Sweet, NuMex Joe E. Parker, and Santa Fe Grande, two cultivars of C. chinense Jacq. Habanero and Pimienta De Chiera, and one accession of C. annuum, NMCA 10652, were evaluated in a field study. Seedlings were transplanted in late May to field raised beds containing loamy sand soils in a semi-arid environment. Plants were well irrigated throughout the experiment. Three saline solution treatments, prepared by adding NaCl, MgSO4, and CaCl2 to tap water at different amounts to create three salinity levels of 0.82 dS m−1 (control, tap water), 2.5 dS m−1, and 4.1 dS m−1 electrical conductivity (EC), were initiated on 15th June and ended in late August. Among the eight varieties, NMCA 10652 had the highest survival percentage at 100% in the 4.1 dS m−1 treatment, followed by ‘Early Jalapeno’, ‘NuMex Sweet’, ‘Pimienta De Chiera’, ‘Santa Fe Grande’, ‘Golden Treasure’, and ‘NuMex Joe E. Parker’. ‘Habanero’ had the lowest survival at 28%. Compared to control, final shoot dry weight of the plants irrigated with saline solution at 4.1 dS m−1 was reduced by 92% in ‘Habanero’, followed by ‘Golden Treasure’ at 80%. For fruit fresh weight in 4.1 dS m−1 vs. control, ‘Habanero’ had the highest reduction at 86%, followed by ‘Golden Treasure’ at 74%, while NMCA 10652 and ‘Santa Fe Grande’ had the least at 26% and 19%, respectively. NMCA 10652, the most tolerant to salinity, had the lowest leaf Na+ accumulation, while ‘Habanero’, the most sensitive to salinity, had the highest Na+ in the leaves. For leaf Cl−, ‘Early Jalapeno’ had the highest, while ‘Habanero’ had the lowest Cl− accumulation in the leaves. Generally, sensitive varieties accumulated more Na+ and/or Cl− in leaves, except for ‘Early Jalapeno’, which was relatively tolerant to salinity but had high Na+ and Cl− accumulation in leaves. 相似文献
126.
127.
Three separate randomized, blinded, vehicle-controlled studies were conducted to determine the effectiveness of a single treatment and consecutive monthly treatments of a combination flavored tablet product containing spinosad and milbemycin oxime (MBO) in the prevention of the establishment of heartworm infections in dogs challenged with recent field isolates of the heartworm (HW), Dirofilaria immitis. For each study, dogs were allocated randomly based on pre-treatment body weights to treated or control groups of 10 animals each. Dogs were infected once with infective HW larvae, on Day-30, using either a Michigan isolate or a Georgia (MP3) isolate of D. immitis. Treatments of beef-flavored chewable tablets were administered in two studies one time either on Day 0 or Day 15, and in one study twice (Days 0 and 30, or Days 15 and 45) or 3 times (Days 0, 30 and 60). For the combination product groups, dosages were in the range of 30-45 mg/kg (13.6-20.5mg/lb) for spinosad and 0.5-0.75 mg/kg (0.2-0.34 mg/lb) for MBO. Necropsies for heartworm counts were completed following euthanasia on Day 120 or Day 123. A single treatment with the combination product of spinosad and MBO 30 or 45 days post-inoculation with infective HW larvae was completely effective (100%) in preventing establishment of the Michigan D. immitis isolate, but efficacy against the Georgia MP3 isolate was incomplete, with geometric mean reductions in HW counts relative to vehicle treated controls of 99% reduction of the 30 day infection and a 98.9% reduction of the 45 day old infection. Against this same MP3 isolate, 3 consecutive monthly treatments provided complete prevention (100%) against establishment of D. immitis infections. The combination product of spinosad and MBO provides effective control of canine heartworms. A single treatment at 30 days post infection showed high but incomplete effectiveness against a heartworm isolate that had been shown to be partially refractory to treatment with marketed monthly heartworm preventives. Three consecutive monthly treatments provided complete control, providing support to the recommendation that heartworm prophylaxis should be maintained year round for optimal effectiveness. 相似文献
128.
The Massachusetts population of the northern red-bellied cooter (Pseudemys rubriventris) is listed as federally endangered due to its extremely restricted geographic range and low population. A captive rearing program has been used since 1984 to augment the population. Blood from 30 juvenile specimens from three rearing institutions was collected prior to release, and hematologic and plasma biochemical data were analyzed. Results were generally consistent with previously published data for other species of the family Emydidae. Basophils were the most numerous type of leucocyte. Results for some values varied significantly between institutions, possibly due to unrecognized differences in husbandry at each facility. 相似文献
129.
Siqueira AK Ribeiro MG Leite Dda S Tiba MR Moura Cd Lopes MD Prestes NC Salerno T Silva AV 《Research in veterinary science》2009,86(2):206-210
The aim of this study was to compare the prevalence of virulence genes in 158 Escherichia coli strains isolated from 51 clinical cases of UTIs, 52 of pyometra and from 55 fecal samples from healthy dogs by PCR. papC was found in 12 (23.5%) strains isolated from UTIs, 19 (36.5%) from pyometra and 10 (18.2%) from feces. papGII was observed in 3 (5.8%) strains from pyometra, and papGIII in 10 (19.6%) from UTIs, 15 (28.8%) from pyometra and 9 (16.4%) from feces. sfaS was detected in 22 (43.1%) strains from UTIs, 24 (46.1%) from pyometra and 19 (34.5%) from feces. hlyA was observed in 17 (33.3%) strains from UTIs, 18 (34.6%) from pyometra and 7 (12.7%) from feces, while cnf-1 was detected in 11 (21.6%) from UTIs, 21 (40.4%) from pyometra and 9 (16.4%) from feces. iucD was observed in 12 (23.5%) strains from UTIs, 9 (17.3%) from pyometra and 1 (1.8%) from feces. usp was found 17 (33.3%) isolates from UTIs and 36 (69.9%) from pyometra. 相似文献
130.
Denise Jarvinen 《Aquaculture Economics & Management (Blackwell Science)》2013,17(3-4):209-225
Abstract Despite a generally uniform federal support infrastructure, aquaculture development in individual states differs widely in the United States. Even among eastern coastal states with shared natural attributes, introduction of reared species and rates of development may differ noticeably. Aquaculture development reflects existing natural, human and physical capital resources and may be influenced by statutes, regulations and public support. One dimension of the existing and emerging industry support involves financial and development programs. This paper presents data on the structure and utilization of public financing programs and nonprofit economic development support by commercial marine and inland aquaculture enterprises in the United States and selected subdivisions. The research illustrates the scope and magnitude of public sector financial support in eight states; however, the costs and benefits of the public investment need to be carefully examined. 相似文献