全文获取类型
收费全文 | 701篇 |
免费 | 45篇 |
专业分类
林业 | 22篇 |
农学 | 18篇 |
基础科学 | 2篇 |
51篇 | |
综合类 | 160篇 |
农作物 | 19篇 |
水产渔业 | 38篇 |
畜牧兽医 | 412篇 |
园艺 | 8篇 |
植物保护 | 16篇 |
出版年
2021年 | 7篇 |
2020年 | 7篇 |
2019年 | 13篇 |
2018年 | 9篇 |
2017年 | 9篇 |
2016年 | 15篇 |
2015年 | 9篇 |
2014年 | 18篇 |
2013年 | 25篇 |
2012年 | 16篇 |
2011年 | 22篇 |
2010年 | 12篇 |
2009年 | 22篇 |
2008年 | 15篇 |
2007年 | 19篇 |
2006年 | 13篇 |
2005年 | 17篇 |
2004年 | 27篇 |
2003年 | 13篇 |
2002年 | 16篇 |
2001年 | 10篇 |
2000年 | 11篇 |
1999年 | 14篇 |
1998年 | 12篇 |
1996年 | 10篇 |
1995年 | 10篇 |
1993年 | 11篇 |
1992年 | 16篇 |
1991年 | 22篇 |
1990年 | 15篇 |
1989年 | 24篇 |
1988年 | 13篇 |
1987年 | 13篇 |
1986年 | 25篇 |
1985年 | 19篇 |
1984年 | 24篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1980年 | 7篇 |
1979年 | 18篇 |
1978年 | 6篇 |
1977年 | 13篇 |
1975年 | 6篇 |
1974年 | 10篇 |
1973年 | 13篇 |
1972年 | 8篇 |
1971年 | 12篇 |
1969年 | 8篇 |
1935年 | 5篇 |
1928年 | 5篇 |
排序方式: 共有746条查询结果,搜索用时 187 毫秒
741.
John W. Harvey Kendal E. Harr David Murphy Michael T. Walsh Elizabeth C. Nolan Robert K. Bonde Melanie G. Pate Charles J. Deutsch Holly H. Edwards William L. Clapp 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2009,38(2):183-193
Background: Hematologic analysis is an important tool in evaluating the general health status of free‐ranging manatees and in the diagnosis and monitoring of rehabilitating animals. Objectives: The purpose of this study was to evaluate diagnostically important hematologic analytes in healthy manatees (Trichechus manatus) and to assess variations with respect to location (free ranging vs captive), age class (small calves, large calves, subadults, and adults), and gender. Methods: Blood was collected from 55 free‐ranging and 63 captive healthy manatees. Most analytes were measured using a CELL‐DYN 3500R; automated reticulocytes were measured with an ADVIA 120. Standard manual methods were used for differential leukocyte counts, reticulocyte and Heinz body counts, and plasma protein and fibrinogen concentrations. Results: Rouleaux, slight polychromasia, stomatocytosis, and low numbers of schistocytes and nucleated RBCs (NRBCs) were seen often in stained blood films. Manual reticulocyte counts were higher than automated reticulocyte counts. Heinz bodies were present in erythrocytes of most manatees. Compared with free‐ranging manatees, captive animals had slightly lower MCV, MCH, and eosinophil counts and slightly higher heterophil and NRBC counts, and fibrinogen concentration. Total leukocyte, heterophil, and monocyte counts tended to be lower in adults than in younger animals. Small calves tended to have higher reticulocyte counts and NRBC counts than older animals. Conclusions: Hematologic findings were generally similar between captive and free‐ranging manatees. Higher manual reticulocyte counts suggest the ADVIA detects only reticulocytes containing large amounts of RNA. Higher reticulocyte and NRBC counts in young calves probably reflect an increased rate of erythropoiesis compared with older animals. 相似文献
742.
743.
LCG Silva CF Lúcio GAL Veiga JA Rodrigues CI Vannucchi 《Reproduction in domestic animals》2009,44(S2):160-163
This study aimed to standardize signs and diagnostic criteria of respiratory function in newborn puppies delivered normally or after dystocia and caesarean operation. A total of 48 neonates were allocated into groups: eutocia (n = 20), dystocia (n = 8), caesarean (c)-section (n = 20). Neonatal health was assessed using the Apgar score and body temperature was determined at 0, 5 and 60 min after delivery. Venous blood gases (pO2 and SO2 ) was measured immediately and 60 min after delivery, and a thoracic radiograph was made between 0 and 5 min of life. The c-section group had significantly lower Apgar scores at birth and 5 min. Hypothermia was present at 5 min in the eutocia and c-section groups, and at 60 min in all groups. The eutocia group had an irregular respiratory pattern in 78% of puppies at birth, 27.7% at 5 min and 21% at 60 min compared with 87.5%, 62.5% and 12.5% of the pups in the dystocia group where there was irregular respiratory rhythm, moderate to intense respiratory sounds with agonic episodes. The c-section group had respiratory alterations in 70%, 45% and 16% of puppies at 0, 5 and 60 min, respectively. Radiographic abnormalities were present in 17% of the pups in the eutocia group, 25% of the pups in the dystocia group and 30% of the pups in the c-section group, respectively. The c-section group had significantly lower SO2 values at 60 min than at birth. All puppies had hypoxaemia, but a significant decrease was observed in the c-section group. Newborn puppies had tissue hypoxia and irregular respiratory pattern at birth. Caesarean-section puppies had lower vitality; however, all developed satisfactory Apgar scores at 5 min of life, regardless of the obstetric condition. 相似文献
744.
JC Monteiro JSA Gonçalves JA Rodrigues CF Lúcio LCG Silva MEOA Assumpção CI Vannucchi 《Reproduction in domestic animals》2009,44(S2):359-362
Poor sperm viability post-thaw has resulted in constant research into methods of cryopreservation of canine semen. One factor that may be involved in poor viability is sperm oxidative stress caused by excessive formation of reactive oxygen species. The present study was performed in order to evaluate the effect of different concentrations of ascorbic acid (AA) and glutathione (Glu) added to an extender for the freeze-thawing of dog sperm. Semen from five mature dogs was collected and frozen in two studies. Prior to and after freezing, sperm motility, morphology and membrane status were examined. In addition, sperm motility was examined up to 120 min after thawing to evaluate thermo-resistance. In study I, semen was collected twice from each dog. On both occasions, semen was divided into three aliquots: control, Glu 1 m m and Glu 5 m m . In study II, semen was collected twice and divided into three aliquots; control, AA 50 μ m and AA 250 μ m . Initial sperm motility was significantly higher in sperm diluted with AA 50 μ m ; sperm longevity, however, measured by a thermal-resistance test (TRT), was higher for Glu treatments. Higher concentration of Glu produced significant improvement in TRT and membrane status, whereas higher concentration of AA had a negative impact in sperm longevity. Antioxidant supplementation to semen freezing extenders improved semen quality post-thaw. Moreover, Glu had the most beneficial effect when supplemented at 5 m m . 相似文献
745.
746.
Chlorpropham is a carbamate herbicide that inhibits cell division and has been widely used as a potato sprout suppressant. Recently we showed that the microalga Dunaliella salina treated with chlorpropham massively accumulated the colourless carotenoids phytoene and phytofluene. Phytoene and phytofluene are valued for their antioxidant, UV-absorption and skin protectant properties; however, they are present in very low quantities in nature. The low toxicity herbicide chlorpropham seems a promising catalyst to produce phytoene in large quantities from CO2 and solar energy with D. salina. This study explored chlorpropham uptake by the algal cells, the formation of potential intermediate metabolites, and the removal of residual chlorpropham from harvested D. salina biomass. Algal biomass rapidly concentrated chlorpropham from culture media. However, washing the harvested biomass with fresh culture medium twice and five times removed ~83 and ~97% of the chlorpropham from the biomass, respectively, and retained algal cell integrity. Furthermore, chloroaniline, a common metabolite of chlorpropham degradation, was not detected in chlorpropham-treated cultures, which were monitored every two days for thirty days. Cells treated with chlorpropham for either 10 min or 24 h continued to over-accumulate phytoene after resuspension in an herbicide-free medium. These data imply that whilst Dunaliella cells do not possess the intracellular capacity to degrade chlorpropham to chloroaniline, the effect of chlorpropham is irreversible on cell nuclear division and hence on carotenoid metabolism. 相似文献