全文获取类型
收费全文 | 369篇 |
免费 | 21篇 |
专业分类
林业 | 34篇 |
农学 | 9篇 |
56篇 | |
综合类 | 73篇 |
农作物 | 16篇 |
水产渔业 | 16篇 |
畜牧兽医 | 160篇 |
园艺 | 5篇 |
植物保护 | 21篇 |
出版年
2023年 | 8篇 |
2022年 | 6篇 |
2021年 | 11篇 |
2020年 | 15篇 |
2019年 | 12篇 |
2018年 | 7篇 |
2017年 | 12篇 |
2016年 | 15篇 |
2015年 | 9篇 |
2014年 | 18篇 |
2013年 | 24篇 |
2012年 | 27篇 |
2011年 | 19篇 |
2010年 | 19篇 |
2009年 | 13篇 |
2008年 | 16篇 |
2007年 | 16篇 |
2006年 | 12篇 |
2005年 | 14篇 |
2004年 | 14篇 |
2003年 | 6篇 |
2002年 | 10篇 |
2001年 | 11篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 6篇 |
1985年 | 9篇 |
1984年 | 14篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1972年 | 3篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有390条查询结果,搜索用时 15 毫秒
381.
Antigens on HTLV-infected cells recognized by leukemia and AIDS sera are related to HTLV viral glycoprotein 总被引:7,自引:0,他引:7
Cross-reactive antigens of molecular size of 61,000 to 68,000 daltons are found on the surface of human cells infected by human T-cell leukemia-lymphoma virus (HTLV). They are recognized by antibodies from patients with adult T-cell leukemias and lymphomas, from healthy carriers of HTLV, and from patients with the acquired immunodeficiency syndrome (AIDS). The latter finding has been one of the major reasons for suggesting an association of HTLV with AIDS. However, whether these antigens are of cellular or viral origin has not been clear. These antigens have now been shown to be associated with the presence of viral proteins in the cells, and a cross-reactive glycoprotein of molecular size of 46,000 daltons has been found to be a consistent structural part of viruses purified from several HTLV-producer cell lines. The findings thus suggest a viral (HTLV) origin of these antigens. 相似文献
382.
Ruggeri L Capanni M Urbani E Perruccio K Shlomchik WD Tosti A Posati S Rogaia D Frassoni F Aversa F Martelli MF Velardi A 《Science (New York, N.Y.)》2002,295(5562):2097-2100
T cells that accompany allogeneic hematopoietic grafts for treating leukemia enhance engraftment and mediate the graft-versus-leukemia effect. Unfortunately, alloreactive T cells also cause graft-versus-host disease (GVHD). T cell depletion prevents GVHD but increases the risk of graft rejection and leukemic relapse. In human transplants, we show that donor-versus-recipient natural killer (NK)-cell alloreactivity could eliminate leukemia relapse and graft rejection and protect patients against GVHD. In mice, the pretransplant infusion of alloreactive NK cells obviated the need for high-intensity conditioning and reduced GVHD. NK cell alloreactivity may thus provide a powerful tool for enhancing the efficacy and safety of allogeneic hematopoietic transplantation. 相似文献
383.
Bernd Weber Ernst A. Stadlbauer Elmar Schlich Sabrina Eichenauer Juergen Kern Diedrich Steffens 《植物养料与土壤学杂志》2014,177(1):84-90
Recycling of P is a common strategy in efficient use of P. The aims of our investigation were to study the P extractability of biochars produced by low temperature conversion and to determine the effect of soda application on low‐temperature conversion of organic compounds and the bioavailability of P to rye grass (Lolium perenne L., cv. Grazer). In this study canola cake, dried distillers grains with solubles, and meat‐and‐bone meal were converted to biochars with thermo‐chemical conversion at 400°C. The P availability was measured in terms of solubility in water, 2% citric, and 2% formic acid, and in a pot experiment with rye grass (Lolium perenne L.) which was cut three times. Application of 8% (w/w) soda to the process of thermo‐chemical conversion of canola cake, dried distillers grains with soluble and meat‐and‐bone meal resulted in an increase of water‐, 2% citric‐, and 2% formic‐acid‐extractable P in the biochars. In contrast to the application of soda, addition of 12% wood ash (w/w) to the conversion of dried distillers grains with solubles resulted in a lower increase of water‐soluble P in the corresponding biochar compared to processing biochar without additives. Addition of biochar P (100 mg P [kg soil]–1) to a Luvisol resulted in an increase of CAL‐extractable soil P. The P uptake of rye grass from biochars produced with the addition of soda was as effective as basic slag and MgNH4 phosphate fertilizers and even better than rock phosphate. 相似文献
384.
Holdsworth M Delpeuch F Landais E Gartner A Eymard-Duvernay S Maire B 《Public health nutrition》2006,9(8):975-981
OBJECTIVE: To assess knowledge of dietary and behaviour-related determinants of non-communicable disease (NCD) of urban Senegalese women. DESIGN: A cross-sectional, population study using an interviewer-administered knowledge questionnaire, developed and validated for this study. The questionnaire consisted of 24 items with six scores measuring knowledge of: (1) diet- and behaviour-related causes of NCD; (2) diet quality-NCD relationship; (3) fruit and vegetable link with NCD; (4) health consequences of obesity; (5) causes of cardiovascular disease (CVD); and (6) causes of certain cancers. SUBJECTS: A random sample of 301 women aged 20-50 years. RESULTS: The knowledge scores developed suggest that the health consequences of obesity (mean score of 65.4%) were best understood followed by causes of CVD (mean score of 60.6%), because obesity, smoking, high blood cholesterol and dietary fat were well recognised as risk factors for CVD. Subjects scored least for their knowledge of the protective effect of fruit and vegetables (mean score of 19.9%). Knowledge of causes of certain cancers (mean score of 36.1%) was also low. Women who worked outside the home had better knowledge for two scores but otherwise no relationship was found between knowledge and literacy, formal education or body mass index. CONCLUSIONS: Findings suggest reasonable overall knowledge concerning diet and behaviour with NCD, especially given the relatively new context of the obesity epidemic in Senegal. However, there was poor knowledge of the benefit of eating fruit and vegetables and other preventable causes of certain cancers. Education targeting the benefits of vegetables and fruit may have the greatest impact on NCD prevention. 相似文献
385.
The importance of demographic niches to tree diversity 总被引:1,自引:0,他引:1
Condit R Ashton P Bunyavejchewin S Dattaraja HS Davies S Esufali S Ewango C Foster R Gunatilleke IA Gunatilleke CV Hall P Harms KE Hart T Hernandez C Hubbell S Itoh A Kiratiprayoon S Lafrankie J de Lao SL Makana JR Noor MN Kassim AR Russo S Sukumar R Samper C Suresh HS Tan S Thomas S Valencia R Vallejo M Villa G Zillio T 《Science (New York, N.Y.)》2006,313(5783):98-101
Most ecological hypotheses about species coexistence hinge on species differences, but quantifying trait differences across species in diverse communities is often unfeasible. We examined the variation of demographic traits using a global tropical forest data set covering 4500 species in 10 large-scale tree inventories. With a hierarchical Bayesian approach, we quantified the distribution of mortality and growth rates of all tree species at each site. This allowed us to test the prediction that demographic differences facilitate species richness, as suggested by the theory that a tradeoff between high growth and high survival allows species to coexist. Contrary to the prediction, the most diverse forests had the least demographic variation. Although demographic differences may foster coexistence, they do not explain any of the 16-fold variation in tree species richness observed across the tropics. 相似文献
386.
Sabrina Lomax Emily Witenden Peter Windsor Peter White 《Veterinary anaesthesia and analgesia》2017,44(1):163-172
Objective
To evaluate the efficacy of a vapocoolant spray to provide local anaesthesia for calves during ear tagging and ear notching.Study design
Randomized study.Animals
Twenty Black Angus calves aged 4–16 weeks old.Methods
Temperature validation studies using thermocouples and a temperature data logger were conducted on dead and live tissue to determine optimal spray distance and duration to achieve tissue anaesthesia (<10 °C). A behavioural trial was conducted to assess efficacy for ear tagging and ear notching. Calves (n = 20) were randomly assigned to the vapocoolant spray (VS) or the water spray (WS) group. A 3 second spray was administered from 10 cm to both sides of the ear immediately prior to ear tagging and ear notching. A numerical rating scale (NRS) was used to score behavioural response to each procedure, with responses categorized from 0 (no response) to 3 (severe).Results
Temperature and tissue validation studies indicated that a vapocoolant spray reduced dead and live tissue temperature to below nociceptive threshold levels (10 °C) for 10–16 seconds. Univariate analysis indicated that ear notching was more painful than ear tagging [odds ratio (OR) = 19.2, 95% confidence interval (CI): 5.34–68.99, p < 0.001]. When adjusted for the multivariate model, there was a significant effect of treatment, with WS calves showing higher pain response scores than VS calves (OR = 4.08, 95% CI: 1.34–12.42, p = 0.011). Ear notching resulted in greater pain response scores than ear tagging (OR = 23.19, 95% CI: 6.18–87.05, p < 0.001).Conclusions
and clinical relevance Vapocoolant spray induced local anaesthesia and significantly reduced the pain response to ear tagging and ear notching in calves. Ear notching is more painful than ear tagging. Cryoanaesthesia is an effective option for reducing the perioperative pain associated with these simple husbandry procedures. 相似文献387.
388.
Md. Khurshid Alam Bhuiyan Sabrina Qureshi Md. Masum Billah Suresh Varma Kammella Md. Rushna Alam Sunuram Ray Md. Mostafa Monwar Abu Hena M. K. 《Water, air, and soil pollution》2018,229(1):14
Recently, Sancti Petri channel on the southwestern (SW) part of Iberian Peninsula has been experiencing urban, industrial, and vehicular expansion. Until recently, there have been only few published reports documenting the pattern of metal accumulation in this estuarine sediment. In the present study, trace metals such as Cu, Zn, Ni, Mn, Pb, Co, Cd, As, and Hg concentrations were analyzed from 69 sediment samples collected from 23 sampling sites of the Santi Petri channel. The magnitude of trace metal accumulation found as the following trend: Mn > Zn > Cu > Pb > Ni > Co > As > Cd > Hg. Spatial distribution pattern demonstrated overall decreasing trend of trace metal from Cadiz Bay mouth to the open ocean mouth, clearly correlative to the presence of anthropogenic inputs. Results of the principle component analysis (PCA) revealed that sediment metal chemistry of Sancti Petri channel is mainly regulated by the concentrations of Pb, Cu, Zn, and Ni; possible sources of those were from vehicular-related emissions. Pollution load index (PLI) and geo-accumulation index (I geo ) indicated overall low values. The study will stimulate improvement of our understanding regarding the pattern of accumulation of metals in the coastal sediments, and the recorded values of metals in the present study can be used as suitable reference for future studies. 相似文献
389.
Lordrick Alinaitwe Clovice Kankya Kathryn J. Allan Sabrina Rodriguez‐Campos Paul Torgerson Anou Dreyfus 《Zoonoses and public health》2019,66(6):636-646
Leptospirosis is a zoonotic bacterial disease reported worldwide. In Uganda, seropositivity has been reported in both humans and domesticated animals, including cattle. However, it remains unknown whether cattle are shedding leptospires and thus acting as potential source for human leptospirosis. We conducted this cross‐sectional study in two cattle abattoirs in Kampala, Uganda between June and July 2017. Kidney and urine samples from 500 cattle sourced from across the country were analysed by real‐time PCR to establish the prevalence of Leptospira‐positive cattle and risk of exposure to abattoir workers. The species of infecting Leptospira was determined by amplification of secY gene and compared to reference sequences published in GenBank. Of 500 cattle tested, 36 (7.2%) had Leptospira DNA in their kidneys (carriers), 29 (5.8%) in their urine (shedders); with an overall prevalence (kidney and/or urine) of 8.8%. Leptospira borgpetersenii was confirmed as the infecting species in three cattle and Leptospira kirschneri in one animal. Male versus female cattle (OR = 3, p‐value 0.003), exotic versus local breeds (OR = 21.3, p‐value 0.002) or cattle from Western Uganda (OR = 4.4, p‐value 0.001) and from regions across the border (OR = 3.3, p‐value 0.032) versus from the central region were more likely to be Leptospira‐positive. The daily risk of exposure of abattoir workers to ≥1 (kidney and/or urine) positive carcass ranged from 27% (95% credibility interval 18.6–52.3) to 100% (95% CI 91.0–100.0), with halal butchers and pluck inspectors being at highest risk. In conclusion, cattle slaughtered at abattoirs in Uganda carry and shed pathogenic Leptospira species; and this may pose occupation‐related risk of exposure among workers in these abattoirs, with workers who handle larger numbers of animals being at higher risk. 相似文献
390.
Marco Schiavon Travis W. Shaddox Karen E. Williams Sergio Gallo P. Agustin Boeri J. Bryan Unruh Jason Kruse Kevin Kenworthy 《Journal of Agronomy and Crop Science》2023,209(1):1-11
Several new bermudagrass cultivars are available and commonly used on golf course fairways. However, little is known about their cultural requirements or how these cultivars perform under lower inputs regimes. A 2-year study was conducted at University of Florida, Fort Lauderdale Research and Education Center, to assess performance of four hybrid bermudagrass [Cynodon dactylon L. Pers. X Cynodon transvaalensis (Burtt-Davy)] cultivars (‘Latitude 36’, ‘Tifway 419’, ‘TifGrand’ and ‘TifTuf’), and 2 common bermudagrass (Cynodon dactylon L. Pers.) cultivars (‘Bimini’ and ‘Celebration’) irrigated at either 50% or 80% reference evapotranspiration (ETo) and fertilised at either 0, 146, 244, or 342 kg N ha−1 year−1. Plots were evaluated monthly for turfgrass quality, dark green colour index (DGCI), normalised difference vegetation index (NDVI), and Chlorophyll Index, and seasonally for N tissue content. Plots watered at 80% ETo enhanced bermudagrass quality compared to 50% ETo, DGCI and NDVI only in two months out of 24. Latitude 36 and Celebration were the top-rated cultivars, and their quality was not affected by no N fertilisation. Conversely, TifGrand, TifTuf and Tifway that received no N fertilisation resulted in insufficient quality during the second year of the study. Insufficient quality may be linked to reduced N metabolization compared to the highest rated cultivars. Results show that new cultivars such as Latitude 36 and Bimini could be maintained at sufficient quality levels with reduced water and N inputs in South Florida. 相似文献