全文获取类型
收费全文 | 9409篇 |
免费 | 748篇 |
国内免费 | 10篇 |
专业分类
林业 | 217篇 |
农学 | 239篇 |
基础科学 | 48篇 |
733篇 | |
综合类 | 330篇 |
农作物 | 191篇 |
水产渔业 | 197篇 |
畜牧兽医 | 7662篇 |
园艺 | 110篇 |
植物保护 | 440篇 |
出版年
2023年 | 105篇 |
2021年 | 40篇 |
2020年 | 245篇 |
2019年 | 66篇 |
2018年 | 207篇 |
2017年 | 233篇 |
2016年 | 163篇 |
2015年 | 202篇 |
2014年 | 307篇 |
2013年 | 439篇 |
2012年 | 351篇 |
2011年 | 434篇 |
2010年 | 340篇 |
2009年 | 407篇 |
2008年 | 360篇 |
2007年 | 275篇 |
2006年 | 254篇 |
2005年 | 244篇 |
2004年 | 290篇 |
2003年 | 286篇 |
2002年 | 334篇 |
2001年 | 287篇 |
2000年 | 235篇 |
1999年 | 223篇 |
1998年 | 220篇 |
1997年 | 213篇 |
1996年 | 197篇 |
1995年 | 194篇 |
1994年 | 182篇 |
1993年 | 201篇 |
1992年 | 255篇 |
1991年 | 220篇 |
1990年 | 264篇 |
1989年 | 203篇 |
1988年 | 155篇 |
1987年 | 203篇 |
1986年 | 101篇 |
1985年 | 134篇 |
1984年 | 141篇 |
1983年 | 131篇 |
1982年 | 88篇 |
1981年 | 41篇 |
1980年 | 38篇 |
1979年 | 39篇 |
1978年 | 46篇 |
1977年 | 47篇 |
1976年 | 43篇 |
1974年 | 41篇 |
1971年 | 34篇 |
1969年 | 42篇 |
排序方式: 共有10000条查询结果,搜索用时 18 毫秒
851.
Exotic animals are becoming increasingly popular and more exotic pet owners are seeking veterinary care. This has led to a demand for properly trained veterinarians who are capable of providing quality, up-to-date medical and surgical treatments. Many surgeries are now performed on exotic pets, and selection of the appropriate suture material is an important part of the treatment protocol. An understanding of different available suture materials, healing times of different tissues, and knowledge of different anatomic and physiologic characteristics in different species is important in the selection of the most appropriate suture material. This review will summarize important aspects of suture selection in exotic animals. 相似文献
852.
853.
The term minimally invasive surgery refers to procedures performed using endoscopic guidance to enter a part of the body (e.g., laparoscopy, thoracoscopy, arthroscopy, rhinoscopy, gastroscopy). Endoscope-assisted procedures generally use a rigid endoscope to improve visualization and/or access or permit completion of the procedure extracorporeally to access internal body structures through small openings compared with traditional “open” incision techniques. Endoscope-assisted procedures currently performed in exotics include, but are not limited to, exploratory laparoscopy/coelioscopy/thoracoscopy, procurement of thoracic and abdominal organ biopsies, intestinal foreign body removal, cystotomy, and reproductive sterilization. 相似文献
854.
855.
Tiffany I. Green DVM Caroline C. Tonozzi DVM DACVECC Rebecca Kirby DVM DACVIM DACVECC Elke Rudloff DVM DACVECC 《Journal of Veterinary Emergency and Critical Care》2011,21(1):36-44
Objective – To test whether an initial plasma lactate≥6.0 mmol/L is associated with the presence of macroscopic gastric wall necrosis and overall survival in dogs presenting with gastric dilatation‐volvulus (GDV). Additionally, if no association was identified we sought to identify a different predictive initial plasma lactate concentration and to examine whether serial plasma lactate concentrations provide better prediction of survival. Design – Retrospective study over a 5‐year period (2003–2007). Setting – Urban private referral small animal teaching hospital. Animals – Eighty‐four client‐owned dogs with a diagnosis of GDV and plasma lactate measurements. Interventions – None. Measurements and Main Results – There was no statistically significant relationship found between survival and the presence of macroscopic gastric wall necrosis with the initial plasma lactate≥6 mmol/L. There was a significant relationship between the initial plasma lactate >2.9 mmol/L for predicting necrosis and <4.1 mmol/L for predicting survival to discharge. Forty dogs that had an increased initial plasma lactate (>2.5 mmol/L) also had a subsequent plasma lactate measured within 12 hours of presentation, with 37/40 dogs surviving and 70% of these surviving dogs having the subsequent lactate decrease by≥50% within 12 hours. The 3/40 that died failed to decrease their plasma lactate by≥50% from the initial blood lactate. Conclusion – The results of this study indicate that an initial presenting plasma lactate concentration≥6.0 mmol/L is not predictive of macroscopic gastric wall necrosis or survival in dogs presenting with GDV. A decrease in plasma lactate concentrations≥50% within 12 hours may be a good indicator for survival. Limitations to the study include its retrospective nature, the small number of patients, and the number of dogs that were euthanized rather than allowed to progress to a natural outcome. 相似文献
856.
Edward E. Payne DVM Brian K. Roberts DVM DACVECC Nick Schroeder DVM DACVIM Ronald L. Burk DVM MS DACVR Thomas Schermerhorn VMD DACVIM 《Journal of Veterinary Emergency and Critical Care》2011,21(3):217-225
Objectives – To (1) determine a reference interval for cardiac troponin I (cTnI) using a point‐of‐care device in normal dogs and compare the results with those published by the manufacturer and (2) determine if cTnI differs among dogs with cardiogenic and noncardiogenic respiratory distress. Design – Prospective observational study. Setting – Emergency and referral veterinary hospital. Animals – Twenty‐six clinically normal dogs and 67 dogs in respiratory distress. Interventions – All dogs underwent whole blood sampling for cTnI concentrations. Measurements and Results – Normal dogs had a median cTnI concentration of 0.03 ng/mL (range 0–0.11 ng/mL). Thirty‐six dogs were diagnosed with noncardiogenic respiratory distress with a median cTnI concentration of 0.14 ng/mL (range 0.01–4.31 ng/mL). Thirty‐one dogs were diagnosed with cardiogenic respiratory distress with a median cTnI concentration of 1.74 ng/mL (range 0.05–17.1 ng/mL). A significant difference between cTnI concentrations in normal dogs and dogs with noncardiogenic respiratory distress was not detected. Significant differences in cTnI concentrations were found between normals versus cardiogenic and cardiogenic versus noncardiogenic respiratory distress groups. Significant differences in cTnI concentrations were identified in >10 when compared with the <5 and the 5–10 years of age groups. Receiver operating curve analysis identified cTnI concentrations >1.5 ng/mL as the optimal “cut‐off point” having a sensitivity of 78% and specificity of 51.5%. The area under the receiver operating curve was 0.72. Overall test accuracy was 65%. Conclusions – cTnI concentrations were significantly increased in dogs with cardiogenic respiratory distress versus dogs with noncardiogenic respiratory distress and normal dogs. A significant difference between normal dogs and dogs with noncardiogenic causes of respiratory distress was detected. Although highly sensitive when cTnI concentrations exceed 1.5 ng/mL, the test has low specificity. Assessment of cTnI by the methodology used cannot be recommended as the sole diagnostic modality for evaluating the cause of respiratory distress in dogs. 相似文献
857.
Imogen C. Johns BVSc DACVIM Anne Desrochers DVM DACVIM Kathryn L. Wotman DVM DACVIM Raymond W. Sweeney VMD DACVIM 《Journal of Veterinary Emergency and Critical Care》2011,21(3):273-278
Objective – To describe the clinical presentation, case management, and outcome in 2 foals with Rhodococcus equi infection associated with presumptive severe immune‐mediated hemolytic anemia. Series Summary – Two foals diagnosed with R. equi pneumonia on the basis of tracheal wash cultures, thoracic radiographs, and thoracic ultrasonography were concurrently diagnosed with hemolytic anemia. Both foals required whole blood transfusions, and were treated with the antimicrobial combination of rifampin and a macrolide (eg, clarithromycin, erythromycin, or azithromycin). Dexamethasone was used to prevent further hemolysis in both foals, and to treat acute lung injury/acute respiratory distress syndrome in 1 of the foals. Both foals survived, and required prolonged antimicrobial therapy. New or Unique Information Provided – Although extra‐pulmonary disorders are commonly diagnosed in foals infected with R. equi, hemolytic anemia is rarely described. Dexamethasone is considered the treatment of choice for immune‐mediated hemolytic anemia, but may be contra‐indicated in foals with severe bacterial infections. In these foals, a relatively low dose and short duration of dexamethasone was utilized in an attempt to minimize immune suppression, although early discontinuation in 1 foal precipitated a second hemolytic crisis. 相似文献
858.
859.
Adesola Odunayo DVM MS DACVECC Marie E. Kerl DVM MPH DACVIM DACVECC 《Journal of Veterinary Emergency and Critical Care》2011,21(3):236-241
Objective – To determine the difference between colloid osmotic pressure (COP) values determined from plasma versus those determined from whole blood. Design – Prospective observational study. Settings – University veterinary teaching hospital. Animals – Fifty‐three healthy dogs. Interventions – None. Measurements and Main Results – Whole blood and plasma COP, CBC, plasma biochemistry. In all dogs, plasma COP values were significantly lower (P=0.02) than whole blood COP, with a mean of difference of 0.5 mm Hg. The mean and median whole blood COP was 21.75 and 21.4 mm Hg, respectively, with a range of 17.9–27.1 mm Hg. The mean and median plasma COP was 21.2 and 20.9 mm Hg with a range of 16.7–28.9 mm Hg. Conclusions – While significant difference exists between plasma and whole blood COP, the individual values are within expected reference intervals for dogs (21–25 mm Hg). Using either sample appears to provide the same information in clinically healthy dog; however, it is recommended that clinicians utilize the same sample type for comparison in an individual patient. 相似文献
860.
Alexander Valverde DVM DVSc DACVA Giacomo Gianotti DVM Eva Rioja DVM PhD DVSc DACVA Amanda Hathway RVT 《Journal of Veterinary Emergency and Critical Care》2011,21(4):328-334
Objective – To compare the determination of cardiac output (CO) via arterial pulse pressure waveform analysis (FloTrac/Vigileo) versus lithium dilution method. Design – Prospective study. Setting – University teaching hospital. Animals – Six adult dogs. Interventions – Dogs were instrumented for CO determinations using lithium dilution (LiDCO) and FloTrac/Vigileo methods. Direct blood pressure, heart rate, arterial blood gases, and end‐tidal isoflurane (ETIso) and CO2 concentrations were measured throughout the study while CO was manipulated with different depth of anesthesia and rapid administration of isotonic crystalloids at 60 mL/kg/h. Measurements and Main Results – Baseline CO measurements were obtained at 1.3% ETIso and were lowered by 3% ETIso. Measurements were obtained in duplicate or triplicate with LiDCO and averaged for comparison with corresponding values measured continuously with the FloTrac/Vigileo method. For 30 comparisons between methods, a mean bias of ?100 mL/kg/min and 95% limits of agreement between ?311 and +112 mL/kg/min (212 mL/kg/min) was determined. The mean (mL/kg/min) of the differences of LiDCO?Vigileo=62.0402+?0.8383 × Vigileo, and the correlation coefficient (r) between the 2 methods 0.70 for all CO determinations. The repeatability coefficients for the individual LiDCO and FloTrac/Vigileo methods were 187 and 400 mL/kg/min, respectively. Mean LiDCO and FloTrac/Vigileo values from all measurements were 145 ± 68 mL/kg/min (range, 64–354) and 244 ± 144 mL/kg/min (range, 89–624), respectively. The overall mean relative error was 48 ± 14%. Conclusion – The FloTrac/Vigileo overestimated CO values compared with LiDCO and the relative error was high, which makes this method unreliable for use in dogs. 相似文献