全文获取类型
收费全文 | 2344篇 |
免费 | 191篇 |
专业分类
林业 | 148篇 |
农学 | 50篇 |
基础科学 | 8篇 |
374篇 | |
综合类 | 320篇 |
农作物 | 118篇 |
水产渔业 | 176篇 |
畜牧兽医 | 1120篇 |
园艺 | 65篇 |
植物保护 | 156篇 |
出版年
2024年 | 10篇 |
2023年 | 21篇 |
2022年 | 32篇 |
2021年 | 69篇 |
2020年 | 79篇 |
2019年 | 74篇 |
2018年 | 83篇 |
2017年 | 76篇 |
2016年 | 78篇 |
2015年 | 58篇 |
2014年 | 88篇 |
2013年 | 112篇 |
2012年 | 142篇 |
2011年 | 189篇 |
2010年 | 86篇 |
2009年 | 91篇 |
2008年 | 122篇 |
2007年 | 113篇 |
2006年 | 92篇 |
2005年 | 105篇 |
2004年 | 85篇 |
2003年 | 86篇 |
2002年 | 61篇 |
2001年 | 32篇 |
2000年 | 30篇 |
1999年 | 26篇 |
1998年 | 12篇 |
1997年 | 13篇 |
1995年 | 16篇 |
1994年 | 9篇 |
1992年 | 23篇 |
1991年 | 20篇 |
1990年 | 9篇 |
1989年 | 18篇 |
1988年 | 21篇 |
1986年 | 15篇 |
1985年 | 12篇 |
1984年 | 15篇 |
1983年 | 11篇 |
1981年 | 9篇 |
1980年 | 13篇 |
1979年 | 10篇 |
1974年 | 11篇 |
1973年 | 15篇 |
1972年 | 20篇 |
1971年 | 16篇 |
1970年 | 12篇 |
1969年 | 8篇 |
1968年 | 9篇 |
1967年 | 9篇 |
排序方式: 共有2535条查询结果,搜索用时 15 毫秒
21.
Julia B. Montgomery Wendy M. Duckett Andrea C. Bourque 《The Canadian veterinary journal. La revue veterinaire canadienne》2009,50(7):751-754
A 6-year-old mare was presented for evaluation of dysuria and pollakiuria. A
pelvic mass, which caused obstruction of urinary outflow, was identified.
Evidence of renal failure was also present. Due to poor prognosis the mare was
euthanized. A postmortem examination revealed a pelvic lymphoma that surrounded
and compressed the urethra. 相似文献
22.
23.
24.
C. Renee Andrea DVM Lisle W. George DVM PhD Diplomate ACVIM 《Veterinary surgery : VS》1999,28(5):311-314
OBJECTIVE: To report surgical correction of hypertrophic periocular fat pads that cause loss of vision and behavioral changes in pot-bellied pigs. STUDY DESIGN: A retrospective study. ANIMALS OR SAMPLE POPULATION: Nine Vietnamese pot-bellied pigs. METHODS: Medical records of nine pot-bellied pigs admitted between 1994 and 1997 for loss of vision associated with hypertrophied periocular fat accumulations were reviewed. Outcome was assessed by contacting owners 4 months to 5 years after surgery. RESULTS: The most common clinical signs were related to impaired vision and included periocular dermatitis, lethargy, and aggressive behavior. Surgical removal of redundant periorbital fat and skin resulted in marked improvement in vision and behavior in all pigs. Overall client satisfaction was excellent. 相似文献
25.
The effects of high intensity exercise on the plasma concentration of lactate, potassium and other electrolytes 总被引:1,自引:0,他引:1
To study the effect of short term high intensity exercise on plasma lactate, potassium, sodium and chloride concentrations, five Thoroughbred horses were galloped on a treadmill at a 5 degree incline. Following a standardised warm-up period, they were galloped at 8, 10, or 12 metres/sec for 2 mins. One horse also galloped at 14 metres/sec for 1.5 mins. Sequential arterial and/or venous blood samples were collected during exercise and recovery. At 12 metres/sec, the effect of different recovery modes, ie, standing, walking or trotting, on the electrolytes was also examined. There was a progressive rise in plasma potassium concentration during galloping, with peak values occurring at the end of the exercise bout. In some cases, values above 10 mmol/litre were recorded at the highest workloads. Plasma lactate concentrations peaked during early recovery, with values up to 32 mmol/litre. A high correlation existed between peak potassium and lactate concentrations (venous r = 0.923, and arterial r = 0.989). Following exercise there was a rapid return to baseline plasma potassium concentrations, but by 12 mins recovery there was still an elevated lactate concentration, the extent depending on the intensity of the exercise bout and the recovery mode. There was a small rise in plasma sodium but no significant change in plasma chloride concentrations during exercise. However, when adjusted for the decrease in plasma volume, as determined from total plasma protein concentration, there was a decrease in circulating amounts of both electrolytes. 相似文献
26.
Strasser A May B Teltscher A Wistrela E Niedermüller H 《Veterinary immunology and immunopathology》2003,94(3-4):113-121
A decline in T-cell-mediated immunity and transient state of immunosuppression after immunization has been reported in dogs. Nevertheless, dogs are still routinely vaccinated with polyvalent live vaccines and severe disease does not generally occur. In order to investigate these effects on the canine immune system and to elucidate possible mechanisms we determined the following immune parameters in the blood of 33 clinically sound German shepherd dogs before and after standard vaccination with a polyvalent vaccine against distemper, parvovirus, viral hepatitis, leptospirosis, kennel cough and rabies: white and differential blood cell count, the serum concentrations and/or activities of IL-1, IL-2, IFN-gamma, TNF-alpha, neopterin and IgG, natural killer (NK) cell activity, bactericidal activity and complement hemolytic activity, lymphocyte proliferation test (LPT) and nitroblue tetrazolium test (NBT).Our major findings were that significant postvaccinal decreases in T-cell mitogenic response to PHA and in neutrophil function and neopterin serum concentration were accompanied by simultaneous increase in plasma IgG and hemolytic complement activity. This suggests a transient shift in the balance between cell-mediated and humoral (T(H)1/T(H)2) immunity rather than immunosuppression.These results do not imply that dogs should not receive live vaccines, as the response to vaccines just seems to create a state of altered homeostasis when immunization elicits protection by humoral and cell-mediated immunity. However, these recognized compromises of immune function should be considered and vaccines still be applied only in healthy animals and strictly according to the rules and regulations given by the manufacturer. 相似文献
27.
Kroll JJ Roof MB Hoffman LJ Dickson JS Harris DL 《Animal health research reviews / Conference of Research Workers in Animal Diseases》2005,6(2):173-197
Proliferative enteropathy (PE; ileitis) is a common intestinal disease affecting susceptible pigs raised under various management systems around the world. Major developments in the understanding of PE and its causative agent, Lawsonia intracellularis, have occurred that have led to advances in the detection of this disease and methods to control and prevent it. Diagnostic tools that have improved overall detection and early onset of PE in pigs include various serological and molecular-based assays. Histological tests such as immunohistochemistry continue to be the gold standard in confirming Lawsonia-specific lesions in pigs post mortem. Despite extreme difficulties in isolating L. intracellularis, innovations in the cultivation and the development of pure culture challenge models, have opened doors to better characterization of the pathogenesis of PE through in vivo and in vitro L. intracellularis-host interactions. Advancements in molecular research such as the genetic sequencing of the entire Lawsonia genome have provided ways to identify various immunogens, metabolic pathways and methods for understanding the epidemiology of this organism. The determinations of immunological responsiveness in pigs to virulent and attenuated isolates of L. intracellularis and identification of various immunogens have led to progress in vaccine development. 相似文献
28.
Rebecca Manley Andrea R. Matthews Federica Morandi George A. Henry Katherine H. DeAnna Gordon Conklin Ann Reed 《Veterinary radiology & ultrasound》2013,54(3):253-262
Motion artifact is an important limiting factor for abdominal magnetic resonance imaging (MRI) in veterinary patients. The purpose of this study was to determine the effects of pulse sequence on abdominal MRI diagnostic quality in dogs. Ten normal dogs were each scanned using 16 MRI pulse sequences. Sequences included breath‐holding sequences, respiratory navigation sequences, and traditional spin‐echo sequences. Four observers independently scored diagnostic quality for each sequence based on the appearance of specific organs, overall diagnostic quality, and degree of artifactual interference. Signal‐to‐noise ratio and contrast‐to‐noise ratio were also calculated for each sequence. The sequence with the highest overall mean diagnostic quality score was the dorsal T2 turbo spin echo (TSE) with fat saturation and breath‐holding. The sequence with the lowest mean diagnostic quality score was the dorsal T2 fast spin echo. The sequence with the highest signal‐to‐noise ratio for all evaluated organs was the sagittal T1 spin echo. Signal‐to‐noise and contrast‐to‐noise ratios did not correlate with subjective assessment of overall diagnostic quality for the majority of the sequences evaluated (P < 0.05). The three sequences considered to have the highest diagnostic quality for the cranial abdomen were the dorsal T2 TSE with fat saturation and breath‐hold, transverse T1 turbo fast low‐angle shot gradient echo with breath‐hold, and dorsal T2 half‐Fourier acquisition single shot TSE with respiratory navigation. These sequences had short acquisition times, yielded studies of similar diagnostic quality, provided complementary information, and are therefore recommended for routine canine abdominal MRI protocols. 相似文献
29.
R.E. Harris B.A. B.Sc. Ph.D. M.R.C.V.S. W.A.G. Charleston B.V.Sc. Ph.D. M.R.C.V.S. M.A.C.V.Sc. 《New Zealand veterinary journal》2013,61(1-2):11-17
Extract From time to time, interest is shown in the use of licks for providing anthelmintic medication to livestock. This paper presents results from two trials on the use, with sheep, of a solidified molasses block incorporating phenothiazine and thiabendazole. 相似文献
30.
Kjelgaard-Hansen M Wiinberg B Aalbaek B Olsen L Harris D Romaschin A Kristensen AT Jensen AL 《Comparative immunology, microbiology and infectious diseases》2008,31(6):477-485
The dog is widely used as a translational experimental model studying the host response and new treatments for human endotoxemia. The present study evaluated the applicability of a novel patient-near neutrophil chemiluminescence assay for the measurement of endotoxin activity in human blood when applied to canine blood samples. The assay was observed to be analytically sensitive and specific to endotoxin when tested in vitro, spiked with purified Escherichia coli lipopolysaccharide and live E. coli. The diagnostic sensitivity was sustained during Gram-positive contamination. Finally, it also demonstrated diagnostic potential when able to discriminate dogs with spontaneously occurring endotoxemia from both healthy dogs and diseased dogs without endotoxemia. The rapid patient-near assessment of endotoxin activity in canine blood should facilitate future studies on endotoxemia in both spontaneous disease and in experimental settings. 相似文献