全文获取类型
收费全文 | 2124篇 |
免费 | 123篇 |
国内免费 | 63篇 |
专业分类
林业 | 240篇 |
农学 | 69篇 |
基础科学 | 23篇 |
380篇 | |
综合类 | 184篇 |
农作物 | 115篇 |
水产渔业 | 215篇 |
畜牧兽医 | 841篇 |
园艺 | 76篇 |
植物保护 | 167篇 |
出版年
2024年 | 5篇 |
2023年 | 24篇 |
2022年 | 34篇 |
2021年 | 64篇 |
2020年 | 48篇 |
2019年 | 44篇 |
2018年 | 93篇 |
2017年 | 85篇 |
2016年 | 81篇 |
2015年 | 47篇 |
2014年 | 77篇 |
2013年 | 151篇 |
2012年 | 119篇 |
2011年 | 131篇 |
2010年 | 102篇 |
2009年 | 92篇 |
2008年 | 102篇 |
2007年 | 106篇 |
2006年 | 77篇 |
2005年 | 99篇 |
2004年 | 56篇 |
2003年 | 95篇 |
2002年 | 98篇 |
2001年 | 95篇 |
2000年 | 64篇 |
1999年 | 47篇 |
1998年 | 21篇 |
1997年 | 13篇 |
1996年 | 15篇 |
1995年 | 29篇 |
1994年 | 14篇 |
1993年 | 9篇 |
1992年 | 16篇 |
1991年 | 6篇 |
1990年 | 10篇 |
1989年 | 19篇 |
1988年 | 15篇 |
1986年 | 10篇 |
1985年 | 9篇 |
1984年 | 5篇 |
1983年 | 8篇 |
1982年 | 4篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1972年 | 5篇 |
1967年 | 9篇 |
1966年 | 6篇 |
排序方式: 共有2310条查询结果,搜索用时 31 毫秒
981.
G Zamaratskaia HK Andersson G Chen K Andersson A Madej K Lundström 《Reproduction in domestic animals》2008,43(3):351-359
The objective of this study, comprising two trials, was to evaluate the effect of a gonadotropin‐releasing hormone (GnRH‐vaccine ImprovacTM; Pfizer Ltd) in a sample of the Swedish pig population. The pigs (n = 120) were assigned to three groups: control (entire male pigs), surgical castration and immunization against GnRH. Surgically castrated pigs did not express detectable levels of either testosterone or estrone sulphate (E1S) in plasma, or androstenone in fat and had lower skatole and indole levels in fat than entire male pigs. Immunization significantly reduced testes weight and bulbourethral gland length, plasma levels of the testicular hormones testosterone and E1S, and fat levels of androstenone, skatole and indole. Skatole levels in plasma were significantly lower than in entire male pigs in the second trial, but not in the first due to overall low skatole levels. All immunized pigs and surgically castrated pigs expressed skatole concentrations in fat below the level of 0.2 μg/g, above which meat is regarded as tainted. In contrast, eight entire male pigs exceeded this level. Indole levels in plasma from immunized pigs were lower than those from entire male pigs. Surgical castration caused lower daily weight gain in the suckling period compared with piglets raised intact, whereas in the post‐weaning period no difference was observed. Immunization resulted in higher feed intake and daily weight gain after the second injection. The estimated lean meat content was improved in comparison with the castrated pigs, but was lower than for entire male pigs. Dressing percentage was lower in immunized pigs than in surgically castrated and entire male pigs. The frequency of skin damage did not differ between immunized and entire male pigs or between immunized and surgically castrated pigs. 相似文献
982.
983.
The present study was conducted to determine the phenological changes in leaf nutrient contents in 10-years Vitis labrusca L. grapes grafted on 140Ru, 5BB and 5C rootstocks. In the experiment, changes of leaf macro and micro element contents from bud burst to post harvest period were investigated in the heavy clay soil conditions. Nutrient contents of leaf blades showed varied depending on the phenological stages and rootstocks (P < 0.01). P, K, Mg and Ca levels of leaf blade exhibited significant differences based on rootstocks and phenological periods between blooming and veraison. While Zn level was obtained sufficient on 5BB of grafted grapevines, it was found to be insufficient in grapevines grafted on 140Ru and 5C rootstocks. In general, grapevines were found insufficient for P, K and Mg nutrients. Total chlorophyll contents of leaves were found at high in the blooming period. Although the highest chlorophyll contents were found in the blooming period, it was determined at the lowest through to harvest. In the study, 5BB rootstock was evaluated to be favorable in terms of nutrient uptake. 相似文献
984.
985.
Bruce W. Keene Clarke E. Atkins John D. Bonagura Philip R. Fox Jens Hggstrm Virginia Luis Fuentes Mark A. Oyama John E. Rush Rebecca Stepien Masami Uechi 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2019,33(3):1127-1140
This report, issued by the ACVIM Specialty of Cardiology consensus panel, revises guidelines for the diagnosis and treatment of myxomatous mitral valve disease (MMVD, also known as endocardiosis and degenerative or chronic valvular heart disease) in dogs, originally published in 2009. Updates were made to diagnostic, as well as medical, surgical, and dietary treatment recommendations. The strength of these recommendations was based on both the quantity and quality of available evidence supporting diagnostic and therapeutic decisions. Management of MMVD before the onset of clinical signs of heart failure has changed substantially compared with the 2009 guidelines, and new strategies to diagnose and treat advanced heart failure and pulmonary hypertension are reviewed. 相似文献
986.
Levente Vrkonyi Zoltn Bokor Jzsef Molnr Ferenc Fodor Zsolt Szri rpd Ferincz dm Staszny Levente Zete Lng Balzs Csorbai Bla Urbnyi Gergely Bernth 《Reproduction in domestic animals》2019,54(3):639-645
In our study, a traditionally used (Grayling, already used in cyprinid species) and a newly tested (Pike) extender was tested to avoid sperm agglutination phenomenon following thawing during carp sperm cryopreservation. A large‐scale (elevated volume of sperm) freezing method in a controlled‐rate freezer using 5 ml straw and 10 ml cryotube was also systematically established. In all experiments, the sperm cryopreserved in using Grayling extender (except only one sample) showed an agglutination phenomenon (damaged and intact cells adhered to each other) after thawing where Pike extender resulted the regular cell suspension. No significant difference was observed between the two cryopreserved groups (Pike and Grayling extender) in all motility parameters using the 0.5 ml straw and the polystyrene box. Similarly, motility parameters did not show a significant difference in the two frozen groups with the 5 ml straw, also in the polystyrene box. A significantly higher progressive motility (pMOT, Grayling: 54% ± 8%, Pike: 37% ± 5%), straight line velocity (VSL, Grayling: 50 ± 5 µm/s, Pike: 39 ± 4 µm/s) and beat cross frequency (BCF, Grayling: 20 ± 1 Hz, Pike: 17 ± 1 Hz) was observed in the case of the grayling extender by the 5 ml straw cryopreserved in a controlled‐rate freezer (CRF) compare to the pike extender. A significantly higher VSL (Grayling: 45 ± 3 µm/s, Pike: 38 ± 4 µm/s) was observed by the grayling extender using the 10 ml cryotube than with the pike extender. Despite the randomly occurring differences in a few parameters, our new controlled freezing method using the newly tested Pike extender, the 5 ml straw or the 10 ml cryotube can be a good solution for the preservation of elevated volume of carp sperm. 相似文献
987.
Rootstocks-scion relations have critical consequences about nutritional status, tree vigour, resistance to pest and pathogens, yield and yield quality. In this study, we therefore investigated seasonal variations of leaf mineral nutrient concentrations in Satsuma mandarin’s cvs. ‘Okitsu’, ‘Clausellina’ and ‘Silverhill’ budded on different citrus rootstocks under Dörtyol-Hatay, Turkey ecological conditions. Nitrogen (N), phosphorus (P) and K (potassium) concentrations of the leaves showed slightly similar trend each other, in general these nutrients reduced from January to March–April, and increased during the growing season until mid- and late summer, then decreased until December. Despite rootstocks did not significantly affect the leaf N, P and K concentrations rootstock-scion relation was pre-eminent and nutrient dependent. Most conspicuous scion dependent changes were recorded for K concentration whereas P concentration was little influenced. In terms of scion-rootstock combination, the range of N and K concentrations were 2.11% (‘Okitsu’/sour orange) to 2.34% (Silverhill/sour orange), and 1.09% (‘Okitsu’/Carrizo citrange) to 1.39% (‘Clausellina’/Carrizo citrange), respectively; but P concentrations were highly similar %0.13 (‘Okitsu’/sour orange) – %0.16 (‘Clausellina’/Carrizo citrange), in the entire growing season. It can be concluded that there are considerable differences in nutrient uptake ability of scion-rootstock combination. 相似文献
988.
Distribution of CD68‐, CD8‐, MHCI‐ and MHCII‐positive cells in the bull and ram testis and epididymis 下载免费PDF全文
B. Güney Saruhan H. Sağsöz E. Akbalık M. A. Ketani S. Erdoğan 《Anatomia, histologia, embryologia》2018,47(4):313-321
The mammalian testis possesses a special immunological environment because of its properties of remarkable immune privilege and effective local innate immunity. The testicular immune privilege protects immunogenic germ cells from systemic immune attack, and local innate immunity is important in preventing testicular microbial infections. Thus, this study aimed to immunohistochemically demonstrate the distribution and localization of CD68‐, CD8‐, MHCI‐ and MHCII‐positive immune cells in the testes and epididymes. Negative immunoreactivity was detected in the seminiferous tubule epithelium and peritubular myoid cells of the testes upon staining in CD68, CD8 and MHC Class I. Positive CD68 immunoreaction was determined in the Sertoli cells and some Leydig cells. The detection of positive cells for CD8 clearly indicated the presence of lymphocytes. Furthermore, the staining with MHCI intensity was ascertained to vary from weak to moderate in the Sertoli and Leydig cells and connective tissue cells. MHCII‐positive immunoreactivity was determined in myoid cells and Leydig cells in the interstitial area. The epithelium of the epididymis showed positive staining for CD68 and CD8, but the stroma displayed a rather weak staining. In the ram epididymis, neither intraepithelial nor interstitial positive reaction was observed for MHCI. In the epididymis, the basal cells displayed a stronger staining for MHCII. In conclusion, these cells not only contribute to local immunity through their direct effects on the quality of fertility in males, but also contribute either directly or indirectly to immune privilege by minimizing the development of both autoimmune reactions and potentially harmful risks. 相似文献
989.
Magdalena Presto Åkerfeldt Sara Holmström Anna Wallenbeck Emma Ivarsson 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2018,68(4):190-201
ABSTRACTThis study investigated how intensively manipulated grass/clover silage (finer structure than chopped silage) fed in total mixed ration (TMR), influenced feed consumption, total tract apparent digestibility (TTAD) and pig behaviour. Ten Yorkshire x Hampshire (YH) pigs were included in a digestibility experiment and 64 YH pigs in a behaviour experiment. Pigs received TMR with 20% dry matter inclusion of either intensively manipulated (SI) or chopped silage (SC). Behaviour was registered with instantaneous and continuous sampling. SI pigs consumed more silage (p?=?0.001) and spent more time eating from the through (p?<?0.01), however no significant difference in TTAD was found (p?>?0.05). Less social interactions prior to feeding (p?=?0.029) and less rooting after feeding (p?<?0.05) were found among SI pigs, indicating SI pigs being more satisfied for a longer time after feeding. We conclude that TMR with intensively manipulated silage benefits feed consumption and increases the opportunities for pigs perform feed-related behaviours. 相似文献
990.
Pharmacokinetics of cefquinome in red‐eared slider turtles (Trachemys scripta elegans) after single intravenous and intramuscular injections 下载免费PDF全文
K. Uney F. Altan G. Cetin M. Aboubakr B. Dik Z. Sayın A. Er M. Elmas 《Journal of veterinary pharmacology and therapeutics》2018,41(1):e40-e44
The purpose of this study was to evaluate the pharmacokinetics of cefquinome (CFQ ) following single intravenous (IV ) or intramuscular (IM ) injections of 2 mg/kg body weight in red‐eared slider turtles. Plasma concentrations of CFQ were determined by high‐performance liquid chromatography and analyzed using noncompartmental methods. The pharmacokinetic parameters following IV injection were as follows: elimination half‐life (t 1/2λz) 21.73 ± 4.95 hr, volume of distribution at steady‐state (V dss) 0.37 ± 0.11 L/kg, area under the plasma concentration–time curve (AUC 0–∞) 163 ± 32 μg hr?1 ml?1, and total body clearance (ClT) 12.66 ± 2.51 ml hr?1 kg?1. The pharmacokinetic parameters after IM injection were as follows: peak plasma concentration (C max) 3.94 ± 0.84 μg/ml, time to peak concentration (T max) 3 hr, t 1/2λz 26.90 ± 4.33 hr, and AUC 0–∞ 145 ± 48 μg hr?1 ml?1. The bioavailability after IM injection was 88%. Data suggest that CFQ has a favorable pharmacokinetic profile with a long half‐life and a high bioavailability in red‐eared slider turtles. Further studies are needed to establish a multiple dosage regimen and evaluate clinical efficacy. 相似文献