全文获取类型
收费全文 | 16389篇 |
免费 | 958篇 |
国内免费 | 1584篇 |
专业分类
林业 | 1473篇 |
农学 | 1648篇 |
基础科学 | 980篇 |
1988篇 | |
综合类 | 6215篇 |
农作物 | 1222篇 |
水产渔业 | 822篇 |
畜牧兽医 | 2841篇 |
园艺 | 918篇 |
植物保护 | 824篇 |
出版年
2024年 | 72篇 |
2023年 | 191篇 |
2022年 | 484篇 |
2021年 | 588篇 |
2020年 | 539篇 |
2019年 | 511篇 |
2018年 | 411篇 |
2017年 | 629篇 |
2016年 | 506篇 |
2015年 | 660篇 |
2014年 | 799篇 |
2013年 | 988篇 |
2012年 | 1269篇 |
2011年 | 1297篇 |
2010年 | 1256篇 |
2009年 | 1110篇 |
2008年 | 1184篇 |
2007年 | 1150篇 |
2006年 | 965篇 |
2005年 | 821篇 |
2004年 | 558篇 |
2003年 | 477篇 |
2002年 | 637篇 |
2001年 | 547篇 |
2000年 | 368篇 |
1999年 | 237篇 |
1998年 | 105篇 |
1997年 | 89篇 |
1996年 | 69篇 |
1995年 | 49篇 |
1994年 | 52篇 |
1993年 | 41篇 |
1992年 | 45篇 |
1991年 | 46篇 |
1990年 | 28篇 |
1989年 | 32篇 |
1988年 | 23篇 |
1987年 | 21篇 |
1986年 | 13篇 |
1985年 | 4篇 |
1983年 | 3篇 |
1981年 | 3篇 |
1976年 | 5篇 |
1974年 | 3篇 |
1972年 | 3篇 |
1967年 | 4篇 |
1966年 | 9篇 |
1965年 | 4篇 |
1962年 | 4篇 |
1955年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 162 毫秒
151.
桑枝屑香菇与杂木屑香菇的品质比较 总被引:3,自引:0,他引:3
以桑枝屑和杂木屑为试材,采用标准及实验室常用方法对香菇营养成分进行测定,研究桑枝屑和杂木屑2种培养料对香菇产量和营养成分(蛋白质、氨基酸、脂肪、多糖、纤维、部分矿质元素)含量的影响。结果表明:桑枝屑栽培的单袋香菇产量比杂木屑的低6.4%,但生物转化率比木屑的高1.7%,粗蛋白质含量是杂木屑栽培的1.03倍,但总氨基酸含量和必需氨基酸含量都比杂木屑香菇中的略低一些;脂肪含量是杂木屑栽培的1.82倍,纤维含量是杂木屑栽培的1.01倍,多糖含量是杂木屑栽培的1.34倍;重金属铅含量仅为杂木屑的11.3%,均达到国家绿色食品标准;矿质元素除钾元素外,钙、镁、铁、锌均高于杂木屑栽培的香菇。可见,用桑枝屑栽培的香菇子实体的营养性和药用保健性优于杂木屑栽培的香菇。 相似文献
152.
153.
为解决新疆吐鲁番地区甜瓜工厂化育苗当中遇到的容易出现徒长苗,不易培育出适龄壮苗等问题,选用甜瓜品种"西州密十七号"为试材,研究不同浓度植物生长延缓剂多效唑(PP333)和比久(B9)浸种处理对甜瓜幼苗质量的影响。结果表明:甜瓜幼苗发芽势随着PP333溶液浓度的增大而降低,幼苗的株高和下胚轴长显著小于对照;浓度为60mg/L的PP333溶液浸种处理下的幼苗叶片厚度和幼苗壮苗指数最大;60mg/L和80mg/L的PP333溶液浸种处理下幼苗根冠比最大。PP333溶液浸种处理对甜瓜幼苗的株高、下胚轴长、叶片大小和厚度的抑制作用大于B9溶液,可以用于防止幼苗徒长,培育壮苗。 相似文献
154.
155.
156.
Park C Yoo JH Jeon HW Kang BT Kim JH Jung DI Lim CY Lee HJ Hahm DH Woo EJ Park HM 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2007,69(9):951-955
Three dogs were presented to us for evaluation of cardiac problems. Electrocardiographic recordings revealed severe tachyarrhythmia and atrial fibrillation with ventricular tachycardia in 2 of the 3 dogs. The echocardiographic findings of the 3 dogs revealed markedly decreased fractional shortening and a marked increase in E-point septal separation. Based on the results of electrocardiographic and echocardiographic evaluation, the 3 dogs were diagnosed as dilated cardiomyopathy (DCM). The dogs were treated with conventional cardiac medication, but cardiac function did not improve and the clinical signs remained. We subsequently attempted treatment with granulocyte-colony stimulating factor (G-CSF; 10 microg/kg, subcutaneously). The specific purpose of G-CSF therapy for DCM was to improve cardiac function and a significant improvement in cardiac function was confirmed. The three dogs had no treatment side effects. This case report suggests that G-CSF might have therapeutic effects for medically refractory DCM in dogs. 相似文献
157.
158.
Glutathione content of in vivo and in vitro matured canine oocytes collected from different reproductive stages 总被引:3,自引:0,他引:3
Kim MK Hossein MS Oh HJ Fibrianto HY Jang G Kim HJ Hong SG Park JE Kang SK Lee BC 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2007,69(6):627-632
Glutathione (GSH) concentrations of oocytes are considered as an important marker of the cytoplasmic maturation. The present study was designed to compare GSH concentrations of in vivo and in vitro matured canine oocytes. In vivo matured oocytes were collected 72 hr after ovulation by flushing fallopian tubes after laparotomy. Ovaries were collected from bitches with different reproductive stages, and collected oocytes were divided into 2 groups according to the size viz. < 120 microm and > 120 microm in diameter and cultured for 72 hr in Tissue Culture Medium-199 supplemented with 10% FBS, 2.2 mg/ml sodium bicarbonate, 2.0 microg/ml estrogen, 0.5 microg/ml FSH, 0.03 IU/ml hCG, and 1% penicillin-streptomycin solution in the presence or absence of 50 microM beta-mercaptoethanol. GSH concentrations were determined by the dithionitrobenzoic acid-glutathione disulfide (DTNB-GSSG) reductase recycling assay. GSH concentrations of immature canine oocytes were 2.9 and 3.8, 3.5 and 6.8, and 3.1 and 6.5 pM/oocyte for < 120 microm and > 120 microm in diameter oocyte groups at anestrous, follicular and luteal stage, respectively (P<0.05). In vivo matured oocytes had significantly higher GSH concentrations compared with in vitro matured oocytes. The GSH content was 19.2 pM/oocyte for in vivo matured oocytes, while 4.1 to 8.1 and 5.7 to 13.2 pM/oocyte for in vitro matured oocytes cultured in the absence or presence of beta-mercaptoethanol, respectively (P<0.05). Presence of beta-mercaptoethanol increased GSH synthesis in canine oocytes cultured in vitro, and oocytes collected from follicular and luteal stage was superior to anestrus oocytes. 相似文献
159.
Kim CS Koh PO Cho JH Park OS Cho KW Kim GS Won CK 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2007,69(6):653-655
A male deformed Korean native calf was examined macroscopically. The deformed calf had no caudal vertebral columns from 5th lumbar vertebra, sacrum and coccygeal vertebrae. The spinal cord was terminated in the vertebral foramen of the 3rd lumbar vertebra. The cervical vertebrae had scoliosis and the 3rd and 4th cervical vertebrae were fused. The 2nd and 3rd lumbar vertebrae were fused and the left and right transverse processes of the 4th lumbar vertebra articulated with ala of the ilium. The rectum was greatly expanded by the imperforate anus and a rectourethral fistula was formed between the rectum and urethra. The deformed calf was recorded as a first documentation of sacrocaudal agenesis confirmed in a Korean native calf. 相似文献
160.
基于"3S"技术的甘肃子午岭自然保护区土地利用变化研究 总被引:1,自引:0,他引:1
以甘肃省子午岭自然保护区为研究对象,运用"3S"技术,对研究区的地形图、不同时相的TM遥感影像进行数据预处理,并分类提取了研究区2个时段的土地利用信息.对分类信息进行统计分析后并与实地调查数据进行比较,结果表明,近20年来甘肃子午岭自然保护区的森林覆盖面积在稳步提高,乔木林面积明显增加.为甘肃子午岭自然保护区工程的建设提供了基础信息,为林区植物种群生长及分布调查研究提供了宏观数据,并且输出了研究区不同时相土地利用专题图. 相似文献