全文获取类型
收费全文 | 763篇 |
免费 | 42篇 |
国内免费 | 1篇 |
专业分类
林业 | 27篇 |
农学 | 11篇 |
基础科学 | 13篇 |
87篇 | |
综合类 | 121篇 |
农作物 | 20篇 |
水产渔业 | 30篇 |
畜牧兽医 | 464篇 |
园艺 | 9篇 |
植物保护 | 24篇 |
出版年
2023年 | 6篇 |
2021年 | 11篇 |
2020年 | 18篇 |
2019年 | 17篇 |
2018年 | 11篇 |
2017年 | 21篇 |
2016年 | 17篇 |
2015年 | 15篇 |
2014年 | 16篇 |
2013年 | 29篇 |
2012年 | 27篇 |
2011年 | 28篇 |
2010年 | 15篇 |
2009年 | 20篇 |
2008年 | 30篇 |
2007年 | 26篇 |
2006年 | 27篇 |
2005年 | 25篇 |
2004年 | 27篇 |
2003年 | 20篇 |
2002年 | 28篇 |
2001年 | 22篇 |
2000年 | 18篇 |
1999年 | 22篇 |
1998年 | 13篇 |
1997年 | 9篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1994年 | 9篇 |
1993年 | 6篇 |
1992年 | 10篇 |
1991年 | 13篇 |
1990年 | 11篇 |
1989年 | 13篇 |
1988年 | 11篇 |
1987年 | 14篇 |
1986年 | 11篇 |
1985年 | 11篇 |
1984年 | 10篇 |
1983年 | 10篇 |
1980年 | 6篇 |
1979年 | 8篇 |
1974年 | 12篇 |
1973年 | 10篇 |
1972年 | 5篇 |
1970年 | 6篇 |
1966年 | 8篇 |
1941年 | 6篇 |
1940年 | 7篇 |
1927年 | 5篇 |
排序方式: 共有806条查询结果,搜索用时 109 毫秒
91.
92.
93.
In a series of greenhouse bioassays, tree seedling growth and root-tip development were compared among soils from two areas that had been clearcut and site prepared 16 years earlier and adjacent, undisturbed forest. Seedlings grown in soil from logged areas were shorter and had fewer root tips than those grown in undisturbed forest soil; however, effects on seedling weights were not consistent among species or experimental series. Fertilizing with nitrogen eliminated size differences due to soil source. In Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco], the only species tested in sterilized soils, sterilization of logged soils resulted in increased seedling size and root-tip formation, whereas sterilization of unlogged soils had either no or a negative effect. 相似文献
94.
95.
96.
P L Rose J P Watkins J A Auer 《Journal of the American Veterinary Medical Association》1984,185(7):795-797
A comminuted, mid-diaphyseal femoral fracture was diagnosed radiographically in a 4-month-old Quarter Horse colt. Disruption of the distal blood supply was suspected, as evidenced by coolness and diminished pulses of the distal portion of the limb. The fracture was repaired by compression plating but the foal's condition continued to deteriorate. A femoral arteriogram of the affected limb was obtained. Positive contrast agent was visible only as far as the mid-shaft of the femur. The foal was euthanatized and the postmortem examination revealed a transected popliteal artery accounting for ischemic necrosis of the distal limb. 相似文献
97.
R J Rose 《The Veterinary record》1978,102(23):498-500
The case histories of four horses with osteomyelitis involving the metacarpal and metatarsal bones are reviewed and the surgical treatments discussed. The horses recovered after curettage of all infected tissue and post operative drainage. The role of antibiotics in treatment is considered and reference is made to the acute treatment of deep wounds to avoid osteomyelitis. 相似文献
98.
Harr KE Raskin RE Heard DJ 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2005,34(4):383-388
BACKGROUND: Few studies have been done to evaluate anticoagulants for use with blood samples from birds and reptiles. Heparin currently is the most commonly used anticoagulant in practice, but may adversely affect blood cell staining and quantitation. OBJECTIVE: The purpose of this study was to evaluate the effects of lithium heparin, K3-EDTA, and sodium citrate, with and without the addition of albumin, on hematologic variables in macaw (Ara sp) and python (Python molurus bivittatus) blood samples. METHODS: Blood samples from 10 macaws and 10 Burmese pythons were collected in heparin-coated syringes and placed into tubes containing either lithium heparin, K3-EDTA, or sodium citrate with and without the addition of 0.25 mL of a 22% bovine serum albumin solution. Cell lysis was determined by counting the number of lysed cells/200 WBCs in Wright's-Giemsa-stained blood smears and by qualitative evaluation of pink plasma in microhematocrit tubes. A CBC was done after 3, 12, and 24 hours of storage at 4 degrees C in anticoagulant-containing tubes and results were compared with those obtained at 0 hour for the heparin-coated syringe sample. A biochemical panel also was done at each time point in similarly stored lithium-heparin samples. RESULTS: Hemolysis was significantly increased in citrated samples from both macaws and pythons beginning at 12 hours. At 24 hours, 19 of 30 (63%) macaw samples in all anticoagulants had >100 lysed cells/200 WBCs. There were no significant differences in hematologic values in samples from pythons collected in heparin or EDTA at any time point. No significant differences were found in the number of lysed cells or in other hematologic data in samples with albumin. Glucose concentration decreased and potassium concentration increased significantly over time in heparinized blood samples. CONCLUSIONS: Based on the results of this study, whole blood samples anticoagulated with lithium heparin or EDTA should be evaluated within 12 hours (macaws) or 24 hours (pythons) of collection and stored at 4 degrees C for best results. Citrate should be avoided as it may result in increased cell lysis. The addition of albumin does not prevent cell lysis. 相似文献
99.
A 16.5 liter spherical ion chamber was constructed of conducting muscle-equivalent plastic and filled to 760 mm-Hg with a muscle-equivalent gas. The use of the chamber for measurements of natural environmental backgrounds was made quite feasible with the aid of the recently developed Shonka vibrating quartz fiber electrometer. This instrument is routinely operable at the extremely high sensitivity of better than 5000 divisions per volt. This system, therefore, has made possible reproducible measurements of absorbed dose-rates of fractions of a micro-rad per hour without any need for the usual corrections for wall-effect, stopping power, and so forth. 相似文献
100.