全文获取类型
| 收费全文 | 94379篇 |
| 免费 | 8217篇 |
| 国内免费 | 43篇 |
专业分类
| 林业 | 3832篇 |
| 农学 | 3800篇 |
| 基础科学 | 632篇 |
| 12319篇 | |
| 综合类 | 13434篇 |
| 农作物 | 3359篇 |
| 水产渔业 | 6967篇 |
| 畜牧兽医 | 50527篇 |
| 园艺 | 1162篇 |
| 植物保护 | 6607篇 |
出版年
| 2021年 | 720篇 |
| 2020年 | 1158篇 |
| 2019年 | 1861篇 |
| 2018年 | 2247篇 |
| 2017年 | 2519篇 |
| 2016年 | 2357篇 |
| 2015年 | 2022篇 |
| 2014年 | 2305篇 |
| 2013年 | 4433篇 |
| 2012年 | 3284篇 |
| 2011年 | 3923篇 |
| 2010年 | 2802篇 |
| 2009年 | 2519篇 |
| 2008年 | 3634篇 |
| 2007年 | 3261篇 |
| 2006年 | 3212篇 |
| 2005年 | 2736篇 |
| 2004年 | 2649篇 |
| 2003年 | 2656篇 |
| 2002年 | 2449篇 |
| 2001年 | 3452篇 |
| 2000年 | 3391篇 |
| 1999年 | 2558篇 |
| 1998年 | 983篇 |
| 1997年 | 1062篇 |
| 1996年 | 887篇 |
| 1995年 | 1026篇 |
| 1994年 | 898篇 |
| 1993年 | 894篇 |
| 1992年 | 1844篇 |
| 1991年 | 1920篇 |
| 1990年 | 1856篇 |
| 1989年 | 1856篇 |
| 1988年 | 1607篇 |
| 1987年 | 1594篇 |
| 1986年 | 1627篇 |
| 1985年 | 1527篇 |
| 1984年 | 1226篇 |
| 1983年 | 1033篇 |
| 1982年 | 716篇 |
| 1979年 | 1061篇 |
| 1978年 | 820篇 |
| 1975年 | 818篇 |
| 1974年 | 899篇 |
| 1973年 | 864篇 |
| 1972年 | 805篇 |
| 1971年 | 795篇 |
| 1970年 | 803篇 |
| 1969年 | 780篇 |
| 1967年 | 734篇 |
排序方式： 共有10000条查询结果，搜索用时 890 毫秒
991.
P.C. Barko M.A. McMichael K.S. Swanson D.A. Williams 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2018,32(1):9-25
The gastrointestinal microbiome is a diverse consortium of bacteria, archaea, fungi, protozoa, and viruses that inhabit the gut of all mammals. Studies in humans and other mammals have implicated the microbiome in a range of physiologic processes that are vital to host health including energy homeostasis, metabolism, gut epithelial health, immunologic activity, and neurobehavioral development. The microbial genome confers metabolic capabilities exceeding those of the host organism alone, making the gut microbiome an active participant in host physiology. Recent advances in DNA sequencing technology and computational biology have revolutionized the field of microbiomics, permitting mechanistic evaluation of the relationships between an animal and its microbial symbionts. Changes in the gastrointestinal microbiome are associated with diseases in humans and animals including inflammatory bowel disease, asthma, obesity, metabolic syndrome, cardiovascular disease, immune‐mediated conditions, and neurodevelopmental conditions such as autism spectrum disorder. While there remains a paucity of data regarding the intestinal microbiome in small animals, recent studies have helped to characterize its role in host animal health and associated disease states. This review is intended to familiarize small animal veterinarians with recent advances in the field of microbiomics and to prime them for a future in which diagnostic tests and therapies will incorporate these developments into clinical practice. 相似文献
992.
Retrospective Evaluation of the Effect of Heart Rate on Survival in Dogs with Atrial Fibrillation 
下载免费PDF全文
下载免费PDF全文 B. Pedro J. Dukes‐McEwan M.A. Oyama M.S. Kraus A.R. Gelzer 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2018,32(1):86-92
Background
Atrial fibrillation (AF) usually is associated with a rapid ventricular rate. The optimal heart rate (HR) during AF is unknown.Hypothesis/Objectives
Heart rate affects survival in dogs with chronic AF.Animals
Forty‐six dogs with AF and 24‐hour ambulatory recordings were evaluated.Methods
Retrospective study. Holter‐derived HR variables were analyzed as follows: mean HR (meanHR, 24‐hour average), minimum HR (minHR, 1‐minute average), maximum HR (maxHR, 1‐minute average). Survival times were recorded from the time of presumed adequate rate control. The primary endpoint was all‐cause mortality. Cox proportional hazards analysis identified variables independently associated with survival; Kaplan‐Meier survival analysis estimated the median survival time of dogs with meanHR <125 bpm versus ≥125 bpm.Results
All 46 dogs had structural heart disease; 31 of 46 had congestive heart failure (CHF), 44 of 46 received antiarrhythmic drugs. Of 15 dogs with cardiac death, 14 had CHF. Median time to all‐cause death was 524 days (Interquartile range (IQR), 76–1,037 days). MeanHR was 125 bpm (range, 62–203 bpm), minHR was 82 bpm (range, 37–163 bpm), maxHR was 217 bpm (range, 126–307 bpm). These were significantly correlated with all‐cause and cardiac‐related mortality. For every 10 bpm increase in meanHR, the risk of all‐cause mortality increased by 35% (hazard ratio, 1.35; 95% CI, 1.17–1.55; P < 0.001). Median survival time of dogs with meanHR<125 bpm (n = 23) was significantly longer (1,037 days; range, 524‐open) than meanHR ≥125 bpm (n = 23; 105 days; range, 67–267 days; P = 0.0012). Mean HR was independently associated with all‐cause and cardiovascular mortality (P < 0.003).Conclusions and Clinical Importance
Holter‐derived meanHR affects survival in dogs with AF. Dogs with meanHR <125 bpm lived longer than those with meanHR ≥ 125 bpm. 相似文献993.
Computed Tomographic Angiography of the Pancreas in Cats with Chronic Diabetes Mellitus Compared to Normal Cats 下载免费PDF全文
下载免费PDF全文 S. Secrest A. Sharma A. Bugbee 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2018,32(3):962-966
Background
Diabetes mellitus (DM) is a common endocrinopathy in cats. No known diagnostic test or patient characteristic at the time of diagnosis can predict likely disease course, unlike in people in whom computed tomographic angiography (CTA) is used. No published data exist regarding the CTA appearance of the pancreas in cats with DM, and thus, it is unknown what if any CTA variables should be further assessed for associations with pancreatic endocrine function.Hypothesis/Objectives
A significant difference in pancreatic attenuation, volume, and size will be identified between normal cats and those with chronic DM on CTA.Animals
Ten healthy control cats and 15 cats with naturally occurring DM present for >12 months.Methods
Prospective cross‐sectional study comparing pancreatic attenuation, enhancement pattern, size, volume, pancreatic volume‐to‐body weight ratio (V:BW), pancreatic arterial: portal phase ratio (A:P), time‐to‐arterial enhancement, and time‐to‐peak portal enhancement on CTA between sedated healthy control cats and those with chronic DM.Results
The pancreas in cats with chronic DM was significantly larger, had higher volume, higher V:BW, and shorter time‐to‐peak portal enhancement on CTA when compared to normal cats.Conclusions and Clinical Importance
Peak portal enhancement time, pancreatic size, pancreatic volume, and V:BW can be used to differentiate normal sedated cats from those with chronic DM by CTA. These variables warrant further investigation to identify possible associations with endocrine function. 相似文献994.
Spectrophotometry and Ultracentrifugation for Measurement of Plasma Lipids in Dogs with Diabetes Mellitus 下载免费PDF全文
下载免费PDF全文 E.C. Seage K.J. Drobatz R.S. Hess 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2018,32(1):93-98
Background
There are conflicting reports of plasma lipoprotein lipid content in dogs with diabetes mellitus (DM).Objectives
To determine lipoprotein lipid content of plasma of dogs with DM by spectrophotometry and ultracentrifugation; to compare lipoprotein lipid content in diabetic and healthy dogs; and to quantify apolipoprotein B‐100 (ApoB) in dogs with DM.Animals
22 dogs with DM and 9 healthy dogs.Methods
Cross‐sectional study. Triglyceride (TG), total cholesterol (TC), and high‐density lipoprotein cholesterol (HDL‐C) concentrations were measured by spectrophotometry. Very low‐density lipoprotein cholesterol (VLDL‐C) and low‐density lipoprotein cholesterol (LDL‐C) concentrations were calculated after ultracentrifugation. Non‐HDL‐C cholesterol was calculated by subtracting HDL‐C from TC. ApoB was quantified by ELISA. The Mann‐Whitney test was used for comparison of median lipoprotein concentrations, and Spearman's correlation was used to assess associations between ApoB and lipoprotein fractions.Results
All values are reported in mg/dL. Median TG (122), TC (343.5), HDL‐C, (200), VLDL‐C, (27) LDL‐C (68), non‐HDL‐C (114), and ApoB (320) were significantly higher in dogs with DM, compared to healthy dogs (57, 197, 168, 12, 16, 31, and 258, respectively, P‐values 0.0079, <0.001, 0.029, 0.011, <0.001, <0.001, 0.025, respectively). A significant association was found between ApoB and LDL‐C (Spearman's rho = 0.41, P = 0.022) and between ApoB and non‐HDL‐C (Spearman's rho = 0.40, P = 0.027).Conclusions and Clinical Importance
Dyslipidemia of dogs with DM is characterized by pronounced increases in LDL‐C and non‐HDL‐C concentrations, although all lipoprotein fractions are significantly increased. Knowledge of specific lipoprotein fraction alterations in dogs with DM can enhance treatment options for diabetic dyslipidemia in dogs. 相似文献995.
996.
Familial Congenital Methemoglobinemia in Pomeranian Dogs Caused by a Missense Variant in the NADH‐Cytochrome B5 Reductase Gene 下载免费PDF全文
下载免费PDF全文 H. Shino Y. Otsuka‐Yamasaki T. Sato K. Ooi O. Inanami R. Sato M. Yamasaki 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2018,32(1):165-171
Background
In veterinary medicine, congenital methemoglobinemia associated with nicotinamide adenine dinucleotide (NADH)‐cytochrome b5 reductase (b5R) deficiency is rare. It has been reported in several breeds of dogs, but little information is available about its etiology.Objectives
To analyze the NADH‐cytochrome b5 reductase gene, CYB5R3, in a Pomeranian dog family with methemoglobinemia suspected to be caused by congenital b5R deficiency.Animals
Three Pomeranian dogs from a family with methemoglobinemia were analyzed. Five healthy beagles and 5 nonrelated Pomeranian dogs without methemoglobinemia were used as controls.Methods
Methemoglobin concentration, b5R activity, and reduced glutathione (GSH) concentration were measured, and a turbidity index was used to evaluate Heinz body formation. The CYB5R3 genes of the affected dog and healthy dogs were analyzed by direct sequencing.Results
Methemoglobin concentrations in erythrocytes of the affected dogs were remarkably higher than those of the control dogs. The b5R activity of the affected dogs was notably lower than that of the control dogs. DNA sequencing indicated that this Pomeranian family carried a CYB5R3 gene missense variant (ATC→CTC at codon 194) that resulted in the replacement of isoleucine (Ile) by leucine (Leu).Conclusions and Clinical Importance
This dog family had familial congenital methemoglobinemia caused by b5R deficiency, which resulted from a nonsynonymous variant in the CYB5R3 gene. This variation (c.580A>C) led to an amino acid substitution (p.Ile194Leu), and Ile194 was located in the proximal region of the NADH‐binding motif. Our data suggested that this variant in the canine CYB5R3 gene would affect function of the b5R in erythrocytes. 相似文献997.
W. G. Haile S. Banerjee A. Ayele T. Mestawet G. Klemetsdal T. Ådnøy 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2018,68(4):174-180
ABSTRACTThe present study was conducted to estimate milk production performance and fit lactation curves for groups of ewes of Local and of Awassi crosses, with a variable blood level, reared under farmer’s environment. The Weigh-Suckle-Weigh method plus hand milking was used to estimate milk yield for ewes. A total of 466 observations from 115 ewes were used. Estimated least-squares adjusted means for the milk production over 120 days were 0.56?kg day?1 (Local), 0.67 (<30% Awassi), 0.86 (30–50% Awassi), and 0.96 (>50% Awassi). Groups with 30–50% Awassi and >50% Awassi ewes produced significantly (p?<?0.05) more milk than Local ewes. Significant differences were observed between <30% Awassi and >50% Awassi crossbred groups. The best crosses (>50% Awassi) produced over 70% more milk than the local ewes which demonstrates the potential that exists in increasing milk production through the initiated crossbreeding programme with sheep in Ethiopia. 相似文献
998.
Barriers to and enablers of implementing antimicrobial stewardship programs in veterinary practices 下载免费PDF全文
下载免费PDF全文 999.
1000.