全文获取类型
收费全文 | 5899篇 |
免费 | 331篇 |
国内免费 | 7篇 |
专业分类
林业 | 290篇 |
农学 | 255篇 |
基础科学 | 16篇 |
1049篇 | |
综合类 | 747篇 |
农作物 | 595篇 |
水产渔业 | 494篇 |
畜牧兽医 | 2286篇 |
园艺 | 75篇 |
植物保护 | 430篇 |
出版年
2023年 | 35篇 |
2022年 | 106篇 |
2021年 | 135篇 |
2020年 | 108篇 |
2019年 | 115篇 |
2018年 | 142篇 |
2017年 | 169篇 |
2016年 | 191篇 |
2015年 | 171篇 |
2014年 | 207篇 |
2013年 | 303篇 |
2012年 | 372篇 |
2011年 | 435篇 |
2010年 | 244篇 |
2009年 | 247篇 |
2008年 | 337篇 |
2007年 | 329篇 |
2006年 | 287篇 |
2005年 | 260篇 |
2004年 | 241篇 |
2003年 | 195篇 |
2002年 | 212篇 |
2001年 | 150篇 |
2000年 | 120篇 |
1999年 | 84篇 |
1998年 | 45篇 |
1997年 | 30篇 |
1996年 | 40篇 |
1995年 | 33篇 |
1994年 | 25篇 |
1993年 | 41篇 |
1992年 | 39篇 |
1991年 | 37篇 |
1990年 | 44篇 |
1989年 | 51篇 |
1988年 | 38篇 |
1987年 | 53篇 |
1986年 | 25篇 |
1985年 | 41篇 |
1984年 | 27篇 |
1983年 | 32篇 |
1981年 | 30篇 |
1980年 | 24篇 |
1979年 | 22篇 |
1978年 | 26篇 |
1977年 | 23篇 |
1976年 | 34篇 |
1974年 | 22篇 |
1973年 | 23篇 |
1972年 | 24篇 |
排序方式: 共有6237条查询结果,搜索用时 15 毫秒
31.
J. M. Lenis M. Ellersieck D. G. Blevins D. A. Sleper H. T. Nguyen D. Dunn J. D. Lee J. G. Shannon 《Journal of Agronomy and Crop Science》2011,197(4):302-310
Salinity reduces crop yield by limiting water uptake and causing ion‐specific stress. Soybean [Glycine max (L.) Merr.] is sensitive to soil salinity. However, there is variability among soybean genotypes and wild relatives for salt tolerance, suggesting that genetic improvement may be possible. The objective of this study was to identify differences in salt tolerance based on ion accumulation in leaves, stems and roots among accessions of four Glycine species. Four NaCl treatments, 0, 50, 75 and 100 mm , were imposed on G. max, G. soja, G. tomentella and G. argyrea accessions with different levels of salinity tolerance. Tolerant genotypes had less leaf scorch and a greater capacity to prevent Na+ and Cl? transport from soil solution to stems and leaves than sensitive genotypes. Magnitude of leaf injury per unit increase in leaf Na+ or Cl? concentrations was lower in tolerant than in susceptible accessions. Also, plant injury was associated more with Na+ rather than with Cl? concentration in leaves. Salt‐tolerant accessions had greater leaf chlorophyll‐meter readings than sensitive genotypes at all NaCl concentrations. Glycine argyrea and G. tomentella accessions possessed higher salt tolerance than G. soja and G. max genotypes. 相似文献
32.
Taesik Yun Yoonhoi Koo Sanggu Kim Wonguk Lee Hakhyun Kim Dongwoo Chang Soochong Kim Mhan-Pyo Yang Byeong-Teck Kang 《The Veterinary quarterly》2021,41(1):163
An 8-year-old neutered male Yorkshire Terrier dog presented with head pressing, vestibular ataxia, neck tenderness, and no oculocephalic reflex. A demarcated lesion in the pons was identified on MRI. The patient was tentatively diagnosed with a glioma and was treated with hydroxyurea plus imatinib and prednisolone. After 30 days of therapeutic treatment, the patient showed a clear improvement in neurological signs, which lasted for 1117 days. On day 569 after the initiation of treatment, 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) was performed with no significant findings on visual analysis. The average and maximal standardized uptake values (SUVs) were 1.92 and 2.29, respectively. The tumor-to-normal-tissue (T/N) ratio was 0.97. The first evidence of clinical deterioration was noticed on day 1147. On day 1155, 3,4-dihydroxy-6-[18F]-fluoro-l-phenylalanine (18F-FDOPA)-PET was performed. High uptake of 18F-FDOPA was observed in the intracranial lesion. The mean and maximal SUVs of the tumor were 1.59 and 2.29, respectively. The T/N ratio was 2.22. The patient was euthanized on day 1155 and histopathologic evaluations confirmed glioma (astrocytoma). This case shows that chemotherapy with hydroxyurea plus imatinib may be considered in the treatment of canine glioma. Furthermore, this is the first case describing the application of 18F-FDG and 18F-FDOPA in a dog with glioma. 相似文献
33.
Kip E. Panter Bryan L. Stegelmeier Dale R. Gardner Clinton A. Stonecipher Stephen T. Lee Don Kitchen Adeline Brackett Charlie Davis 《Journal of veterinary diagnostic investigation》2021,33(3):538
Salvia reflexa (lance-leaf sage)-contaminated alfalfa hay was fed to ~500 mixed-breed beef cattle. Within hours of exposure, nearly half of the cattle developed lethargy, anorexia, depression, and recumbency, followed by bellowing, colic, and death. Even though the uneaten contaminated hay was removed the first day, nearly 100 animals died within the first 48 h. Three of these cattle were examined postmortem, and tissues and hay samples were collected for microscopic and chemical analysis. Several days later, a smaller number of the clinically poisoned cattle developed neurologic disease with aberrant behavior, aggression, icterus, blindness, exhaustion, and death. A total of 165 cattle were fatally poisoned. Poisoned cattle had swollen, dark, mottled livers that had a prominent nutmeg-like lobular pattern on cut section. Histologically, there was severe centrilobular-to-panlobular hepatic necrosis with marked hepatocellular swelling, degeneration, and necrosis. The surviving cattle developed liver disease characterized by altered serum biochemical analyses and microscopic hepatocellular degeneration and necrosis. In subsequent biopsies and analysis, these lesions resolved within 6–7 mo. After confirming toxicity of the hay in cattle, goats, and mice, followed by a mouse bioassay–guided chemical fractionation process, Salvia reflexa was identified as the contaminant in the hay responsible for the hepatotoxicity. S. reflexa has not been reported previously to cause fatal hepatotoxicity in livestock in North America, to our knowledge. 相似文献
34.
Hyunseok Kim Min Jang Chi Won Shin Hyungjoo Han Jeesoo Cha Inhyung Lee Won-gyun Son 《Veterinary anaesthesia and analgesia》2021,48(1):92-100
ObjectiveTo describe an approach for ethmoidal nerve block (EBLOCK) and to compare the effects of a maxillary nerve block (MBLOCK), EBLOCK and their combination (M-EBLOCK) on heart rate (HR), systolic (SAP), mean (MAP), diastolic (DAP) arterial pressures and respiratory rate (fR) during nasal stimulation in dogs.Study designProspective, blinded, randomized, crossover placebo-controlled study.AnimalsBeagle dogs (five cadavers, nine live dogs), with a median (interquartile range) weight of 10.5 (10.3–11.0) kg.MethodsThe accuracy of iohexol injections (each 1 mL) at the maxillary and ethmoidal foramina in cadavers was evaluated using computed tomography. Then, anesthetized dogs were administered four bilateral treatments separated by 1 week, saline or 2% lidocaine 1 mL per injection: injections of saline at the maxillary and ethmoidal foramina (Control), injections of lidocaine at the maxillary foramina and saline at the ethmoidal foramina (MBLOCK), injections of saline at the maxillary foramina and lidocaine at the ethmoidal foramina (EBLOCK) and injections of lidocaine at all foramina (M-EBLOCK). The ventral nasal meatus was bilaterally stimulated using cotton swabs, and HR, SAP, MAP, DAP and fR were continuously recorded. Values for each variable were compared before and after stimulation using Wilcoxon signed-rank test. Changes in variables among treatments were analyzed using Mann–Whitney U and Kruskal–Wallis tests (p ≤ 0.05).ResultsComputed tomography revealed iohexol distribution around the openings of the target foramina in all cadavers. In living dogs, HR, SAP, MAP, DAP and fR significantly increased after stimulation within each treatment (p < 0.03). Physiologic responses were significantly attenuated, but not absent, in the M-EBLOCK [HR (p = 0.019), SAP, MAP, DAP and fR (all p ≤ 0.001)] compared with those in the Control.Conclusions and clinical relevanceConcurrent injections of lidocaine at the maxillary and ethmoidal foramina attenuated HR, arterial pressure and fR responses to nasal stimulation in Beagle dogs. 相似文献
35.
Wei‐Shan Lee Jih‐Jong Lee Albert Taiching Liao Chia‐Lien Kao Shang‐Lin Wang 《Veterinary and comparative oncology》2021,19(1):53-60
The majority of the known prognostic factors in dogs with lymphoma have been evaluated before treatment commences or at the time of diagnosis. Prognostic factors evaluated during the initial phase of treatment are less described but may provide important clinical information. In this retrospective study, 82 canine lymphoma patients were categorized according to the weight change between diagnosis and after 5 weeks of chemotherapy. Dogs that gained greater than 5% or lost greater than 5% of initial body weight were categorized as increased‐ or decreased‐weight groups, respectively. Those in which weight changed less than 5% were categorized as the maintained‐weight group. The median progression‐free survival (PFS) in the increased‐weight group, maintained‐weight group and decreased‐weight group was 226, 256 and 129 days, respectively. The decreased‐weight group had significantly shorter PFS than the increased and maintained groups (P = .023, P = .003, respectively). The median survival time (ST) in the increased‐weight group, maintained‐weight group and decreased‐weight group was 320, 339 and 222 days, respectively. There was no significant difference in ST among the three groups (P = .128). In Cox‐regression results, weight change group and initial body weight were significant risk factors associated to PFS (P = .007, P = .001, respectively) while only patient's initial body weight was a significant risk factor to ST (P = .013). In conclusion, evaluation of initial body weight and weight changes over time can provide valuable information regarding PFS and ST in dogs with multicentric lymphoma. 相似文献
36.
37.
Jee-Hoon Lee Ik-Jae Kang A-Reum Kim You-Sun Noh Hee-Chun Chung Bong-Kyun Park 《Journal of veterinary science (Suw?n-si, Korea)》2016,17(2):253-256
This study was conducted to determine if humoral antibody response of foot-and-mouth disease (FMD) vaccine improved in 8-week-old growing pigs born to well-vaccinated sows pre-treated with 60 mg of poly-γ-glutamic acid (γ-PGA) three days before vaccination. Antibody against FMD virus serotype O was measured 0, 2, 4 and 6 weeks post-vaccination, using a PrioCHECK FMDV type O ELISA kit. The results showed that positive antibody reactions against FMDV serotype O antigen among a component of the vaccine significantly increased in response to pre-injection with γ-PGA. 相似文献
38.
Woo-Jung Park Byung-Joo Park Hee-Seop Ahn Joong-Bok Lee Seung-Yong Park Chang-Seon Song Sang-Won Lee Han-Sang Yoo In-Soo Choi 《Journal of veterinary science (Suw?n-si, Korea)》2016,17(1):1-11
Hepatitis E outbreaks are a serious public health concern in developing countries. The disease causes acute infections, primarily in young adults. The mortality rate is approximately 2%; however, it can exceed 20% in pregnant women in some regions in India. The causative agent, hepatitis E virus (HEV), has been isolated from several animal species, including pigs. HEV genotypes 3 and 4 have been isolated from both humans and animals, and are recognized as zoonotic pathogens. Seroprevalence studies in animals and humans indirectly suggest that HEV infections occur worldwide. The virus is primarily transmitted to humans via undercooked animal meats in developed countries. Moreover, transfusion- and transplantation-mediated HEV infections have recently been reported. This review summarizes the general characteristics of hepatitis E, HEV infection status in animals and humans, the zoonotic transmission modes of HEV, and HEV vaccine development status. 相似文献
39.
Apparent ileal digestibility of nutrients and amino acids in soybean meal,fish meal,spray‐dried plasma protein and fermented soybean meal to weaned pigs 下载免费PDF全文
This study sought to determine whether fermentation could increase apparent ileal digestibility (AID) of dry matter (DM), nitrogen (N), energy (E) and amino acids (AA) in fermented soybean meal (FSBM) greater than that of soybean meal (SBM) in weaned pigs. Four weaned pigs (10.00 ± 0.30 kg) were surgically equipped with T‐cannulas and randomly followed a 4 × 4 Latin square design of treatments (SBM, FSBM, fish meal and spray‐dried plasma protein). Overall, the fermentation process was able to reduce the amount of anti‐nutritional factors (ANF), including trypsin inhibitors, raffinose and stachyose, in the FSBM diet, which were significantly reduced by 39.4, 92.2, and 92.9%, respectively, as compared to the SBM diet. As a consequence of ANF reduction in FSBM, the AID of DM, N and E as well as AA was significantly greater with FSBM than SBM. Taken all together, the fermentation process improved the nutritional quality of SBM, due to ANF reduction, leading to improvement of digestibility of AA. As such, FSBM can be potentially used as a specialized feed ingredient, especially for young animal diets in an attempt to reduce diet costs. 相似文献
40.
Rita M. Hanel DVM DACVIM DACVECC Lee Palmer DVM MS DACVECC NREMT‐T WEMT CCRP Janice Baker DVM DACVPM Jo‐Anne Brenner BA EMT‐I EMT‐T David Dorman DVM PhD DABVT John C. Gicking DVM DACVECC Brian Gilger DVM MS DACVO DABT Cynthia M. Otto DVM PhD DACVECC DACVSMR Elizabeth Rozanski DVM DACVECC DACVIM Brian Trumpatori DVM 《Journal of Veterinary Emergency and Critical Care》2016,26(2):166-233