全文获取类型
收费全文 | 12082篇 |
免费 | 830篇 |
专业分类
林业 | 1592篇 |
农学 | 427篇 |
基础科学 | 48篇 |
2662篇 | |
综合类 | 766篇 |
农作物 | 503篇 |
水产渔业 | 790篇 |
畜牧兽医 | 4712篇 |
园艺 | 298篇 |
植物保护 | 1114篇 |
出版年
2023年 | 103篇 |
2022年 | 132篇 |
2021年 | 240篇 |
2020年 | 229篇 |
2019年 | 157篇 |
2018年 | 557篇 |
2017年 | 531篇 |
2016年 | 475篇 |
2015年 | 388篇 |
2014年 | 440篇 |
2013年 | 667篇 |
2012年 | 928篇 |
2011年 | 849篇 |
2010年 | 465篇 |
2009年 | 352篇 |
2008年 | 718篇 |
2007年 | 682篇 |
2006年 | 555篇 |
2005年 | 576篇 |
2004年 | 525篇 |
2003年 | 479篇 |
2002年 | 393篇 |
2001年 | 279篇 |
2000年 | 243篇 |
1999年 | 225篇 |
1998年 | 69篇 |
1997年 | 58篇 |
1996年 | 44篇 |
1995年 | 64篇 |
1994年 | 38篇 |
1993年 | 34篇 |
1992年 | 81篇 |
1991年 | 66篇 |
1990年 | 61篇 |
1989年 | 56篇 |
1988年 | 55篇 |
1987年 | 48篇 |
1986年 | 49篇 |
1985年 | 48篇 |
1984年 | 43篇 |
1983年 | 37篇 |
1979年 | 37篇 |
1974年 | 30篇 |
1948年 | 31篇 |
1942年 | 49篇 |
1941年 | 32篇 |
1940年 | 36篇 |
1939年 | 45篇 |
1938年 | 28篇 |
1935年 | 36篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Analgesic efficacy of an oral transmucosal spray formulation of meloxicam alone or in combination with tramadol in cats with naturally occurring osteoarthritis 下载免费PDF全文
62.
Marie-Etancelin C Basso B Davail S Gontier K Fernandez X Vitezica ZG Bastianelli D Baéza E Bernadet MD Guy G Brun JM Legarra A 《Journal of animal science》2011,89(3):669-679
Genetic parameters of traits related to hepatic lipid metabolism, carcass composition, and product quality of overfed mule ducks were estimated on both parental lines of this hybrid: the common duck line for the maternal side and the Muscovy line for the paternal side. The originality of the statistical model was to include simultaneously the additive genetic effect of the common ducks and that of the Muscovy ducks, revealing a greater genetic determinism in common than in Muscovy. Plasma metabolic indicators (glucose, triglyceride, and cholesterol contents) were heritable, in particular at the end of the overfeeding period, and heritabilities increased with the overfeeding stage. Carcass composition traits were highly heritable in the common line, with values ranging from 0.15 for liver weight, 0.21 for carcass weight, and 0.25 for abdominal fat weight to 0.32 for breast muscle weight. Heritabilities of technological outputs were greater for the fatty liver (0.19 and 0.08, respectively, on common and Muscovy sides for liver melting rate) than for the pectoralis major muscle (between 0.02 and 0.05 on both parental sides for cooking losses). Fortunately, the processing industry is mainly facing problems in liver quality, such as too high of a melting rate, than in meat quality. The meat quality appraisal criteria (such as texture and cooking losses), usually dependent on pH and the rate of decline of pH, were also very lowly heritable. This study demonstrated that genetic determinism of meat quality and ability of overfeeding is not similar in the common population and in the Muscovy population; traits related to fattening, muscle development, and BW have heritability values from 2 to 4 times greater on the common line than on the Muscovy line, which is relevant for considering different selection strategies. 相似文献
63.
Emaga Thomas Happi Bindelle Jérôme Agneesens Richard Buldgen André Wathelet Bernard Paquot Michel 《Tropical animal health and production》2011,43(1):171-177
Musa sp. peels are widely used by smallholders as complementary feeds for cattle in the tropics. A study of the influence of the
variety and the maturation stage of the fruit on fermentability and metabolisable energy (ME) content of the peels was performed
using banana (Yangambi Km5) and plantain (Big Ebanga) peels at three stages of maturation in an in vitro model of the rumen.
Peel samples were analysed for starch, free sugars and fibre composition. Samples were incubated in the presence of rumen
fluid. Kinetics of gas production were modelled, ME content was calculated using prediction equation and short-chain fatty
acids production and molar ratio were measured after 72 h of fermentation. Final gas production was higher in plantain (269–339 ml
g−1) compared to banana (237–328 ml g−1) and plantain exhibited higher ME contents (8.9–9.7 MJ/kg of dry matter, DM) compared to banana (7.7–8.8 MJ/kg of DM). Butyrate
molar ratio decreased with maturity of the peels. The main influence of the variety and the stage of maturation on all fermentation
parameters as well as ME contents of the peels was correlated to changes in the carbohydrate fraction of the peels, including
starch and fibre. 相似文献
64.
The EFSA quantitative approach to pest risk assessment – methodological aspects and case studies 下载免费PDF全文
G. Gilioli G. Schrader J.‐C. Grégoire A. MacLeod O. Mosbach‐Schulz T. Rafoss V. Rossi G. Urek W. van der Werf 《EPPO Bulletin》2017,47(2):213-219
A new method for pest risk assessment and the identification and evaluation of risk‐reducing options is currently under development by the European Food Safety Authority (EFSA) Plant Health Panel. The draft method has been tested on pests of concern to the European Union (EU). The method is adaptable and can focus either on all the steps and sub‐steps of the assessment process or on specific parts if necessary. It is based on assessing changes in pest population abundance as the major driver of the impact on cultivated plants and on the environment. Like other pest risk assessment systems the method asks questions about the likelihood and magnitude of factors that contribute to risk. Responses can be based on data or expert judgment. Crucially, the approach is quantitative, and it captures uncertainty through the provision by risk assessors of quantile estimates of the probability distributions for the assessed variables and parameters. The assessment is based on comparisons between different scenarios, and the method integrates risk‐reducing options where they apply to a scenario, for example current regulation against a scenario where risk‐reducing options are not applied. A strategy has been developed to communicate the results of the risk assessment in a clear, comparable and transparent way, with the aim of providing the requestor of the risk assessment with a useful answer to the question(s) posed to the EFSA Plant Health Panel. The method has been applied to four case studies, two fungi, Ceratocystis platani and Cryphonectria parasitica, the nematode Ditylenchus destructor and the Grapevine flavescence dorée phytoplasma. Selected results from these case studies illustrate the types of output that the method can deliver. 相似文献
65.
Abed C Legrave N Dufies M Robert G Guérineau V Vacelet J Auberger P Amade P Mehiri M 《Marine drugs》2011,9(7):1210-1219
Chemical investigation of the Mediterranean sponge Sarcotragus spinosulus led to the isolation of a new hydroxylated nonaprenylhydroquinone, along with two known metabolites, hepta- and octaprenylhydroquinones. The structure of the new metabolite was assigned by extensive 1D and 2D NMR analyses and MS studies. The antileukemic effect of the three compounds towards the chronic myelogenous leukemia (CML) cells line K562 was also evaluated. 相似文献
66.
The sialyl transferase of disialoganglioside formation is depressed in mammary tumors induced in the rat by 7,12-dimethylbenz[a]anthracene. Specific activities of other glycosyltransferases of the pathway ceramide to monosialo-ganglioside are unchanged or elevated so that the ganglioside GM(1) accumulates and higher gangliosides are depressed. These findings with a solid tumor are critical to an involvement of gangliosides in the cell-surface changes of tumorigenesis. 相似文献
67.
Treatment of canine parvoviral enteritis with interferon-omega in a placebo-controlled challenge trial 总被引:3,自引:0,他引:3
Martin V Najbar W Gueguen S Grousson D Eun HM Lebreux B Aubert A 《Veterinary microbiology》2002,89(2-3):115-127
Canine parvoviral enteritis continues to cause significant morbidity and mortality in dogs worldwide, and efficacious antiviral therapies are lacking. The present trial was aimed at evaluating the therapeutic efficacy of a recombinant feline interferon (type omega) preparation in the treatment of parvoviral enteritis in dogs. A double-blind, placebo-controlled challenge trial was performed in beagle pups (8-9 weeks); clinical signs, body weight, hematologic parameters, and mortality were monitored for a period of 14 days after challenge. Fourteen animals were inoculated with virulent canine parvovirus; 10 animals that developed clinical signs thereby meeting the inclusion criteria were admitted to the treatment phase in two randomly selected groups (placebo and IFN) of equal size. The IFN group received daily intravenous injections of rFeIFN-omega (2.5 MU/kg) for three consecutive days. The placebo group received daily injections of saline without IFN. Both groups of animals received individual supportive treatment consisting of adjusted diet and electrolyte solution.All five dogs in the placebo group developed fulminating enteritis with typical clinical signs and died within 10 days post-inoculation (or 6 days post-treatment). In the IFN-treated group, one animal died on day 2 after the treatment was started, whereas the other four dogs survived the challenge and gradually recovered. Our data confirm that the rFeIFN-omega can exert a significant therapeutic effect on dogs with parvoviral enteritis by improving clinical signs and reducing mortality. 相似文献
68.
69.
C. Ekstrand C. Ingvast‐Larsson L. Olsén M. Hedeland U. Bondesson J. Gabrielsson 《Journal of veterinary pharmacology and therapeutics》2016,39(3):255-263
The cortisol response to glucocorticoid intervention has, in spite of several studies in horses, not been fully characterized with regard to the determinants of onset, intensity and duration of response. Therefore, dexamethasone and cortisol response data were collected in a study applying a constant rate infusion regimen of dexamethasone (0.17, 1.7 and 17 μg/kg) to six Standardbreds. Plasma was analysed for dexamethasone and cortisol concentrations using UHPLC‐MS/MS. Dexamethasone displayed linear kinetics within the concentration range studied. A turnover model of oscillatory behaviour accurately mimicked cortisol data. The mean baseline concentration range was 34–57 μg/L, the fractional turnover rate 0.47–1.5 1/h, the amplitude parameter 6.8–24 μg/L, the maximum inhibitory capacity 0.77–0.97, the drug potency 6–65 ng/L and the sigmoidicity factor 0.7–30. This analysis provided a better understanding of the time course of the cortisol response in horses. This includes baseline variability within and between horses and determinants of the equilibrium concentration–response relationship. The analysis also challenged a protocol for a dexamethasone suppression test design and indicated future improvement to increase the predictability of the test. 相似文献
70.
The objective of this study was to investigate the effect of infusing whole dead semen (WDS) after AI with diluted commercial semen on uterine inflammatory reaction and embryonic survival rate in gilts. Sixty Yorkshire-Landrace gilts were assigned at their second estrus to one of the following AI treatments: 1) commercial semen adjusted to 1 x 10(9) sperm cells (S1) per dose, followed by an infusion of 80 mL of WDS (S1-WDS); 2) S1 followed by an infusion of 80 mL of Beltsville Thawing Solution (S1-BTS); 3) commercial semen adjusted to 3 x 10(9) sperm cells (S3) per dose, followed by an infusion of 80 mL of BTS (S3-BTS); and 4) a negative control group, in which gilts received two infusions of 80 mL of BTS (BTS). Two days after the first AI, eight gilts from Groups 1, 2, and 4 were slaughtered and reproductive tracts were collected. One horn was cut open longitudinally along the antimesometrial aspect and endometrial samples were taken and immediately frozen for analysis of messenger RNA (mRNA) abundance for inflammatory cytokines and growth factors. The other horn was flushed with 20 mL of PBS, and the contents of interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta1 (TGF-beta1) were determined by ELISA. On d 25 after AI, gilts from Groups 1, 2, and 3 were slaughtered and their reproductive tracts were collected to evaluate the number of fetuses and corpora lutea. On d 2 after the first AI, only TGF-beta1 was detected in the flush of all gilts, and no difference was observed between S1-WDS, S1-BTS, and BTS gilts. Endometrial levels of IFN-gamma and interleukin (IL)-6 mRNA were marked in all gilts, but they were not affected by the AI treatments, whereas the mRNA abundances for IL-1 and IL-2 were negligible. Infusions of WDS or BTS after a fertile AI did not affect IGF-I, IGF-I receptor, or IGF-II mRNA levels compared with gilts infused with BTS only, whereas the mRNA abundance for the IGF-II receptor was decreased (P < 0.05) in WDS-infused gilts. In gilts inseminated with S1 doses, infusion of WDS did not affect the number of live embryos. Although infusions of WDS did not affect the mRNA level and secretion of the cytokines measured and did not improve embryonic survival rates, further studies are needed to better understand the influence of semen composition on the uterine response after mating. 相似文献