全文获取类型
收费全文 | 26251篇 |
免费 | 1109篇 |
国内免费 | 2143篇 |
专业分类
林业 | 2925篇 |
农学 | 1967篇 |
基础科学 | 3735篇 |
3518篇 | |
综合类 | 12581篇 |
农作物 | 758篇 |
水产渔业 | 804篇 |
畜牧兽医 | 1840篇 |
园艺 | 523篇 |
植物保护 | 852篇 |
出版年
2024年 | 121篇 |
2023年 | 329篇 |
2022年 | 527篇 |
2021年 | 650篇 |
2020年 | 657篇 |
2019年 | 753篇 |
2018年 | 478篇 |
2017年 | 764篇 |
2016年 | 1047篇 |
2015年 | 925篇 |
2014年 | 1350篇 |
2013年 | 1288篇 |
2012年 | 2051篇 |
2011年 | 2203篇 |
2010年 | 1704篇 |
2009年 | 1759篇 |
2008年 | 1735篇 |
2007年 | 2028篇 |
2006年 | 1653篇 |
2005年 | 1417篇 |
2004年 | 1006篇 |
2003年 | 866篇 |
2002年 | 669篇 |
2001年 | 588篇 |
2000年 | 448篇 |
1999年 | 378篇 |
1998年 | 338篇 |
1997年 | 281篇 |
1996年 | 263篇 |
1995年 | 237篇 |
1994年 | 201篇 |
1993年 | 185篇 |
1992年 | 147篇 |
1991年 | 90篇 |
1990年 | 128篇 |
1989年 | 81篇 |
1988年 | 90篇 |
1987年 | 36篇 |
1986年 | 13篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1956年 | 2篇 |
1955年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
The IgG index measures the intrathecal immunoglobulin production and it is a useful tool for diagnosis of inflammatory diseases involving the central nervous system. This index is based on the precise quantification of albumin and IgG in canine cerebrospinal fluid and serum. Here, we report the development of an indirect competitive ELISAs for the detection of both antigens. Thirty-two dogs were included in this study, divided into three experimental groups. Group A was composed of 22 healthy animals, as determined by standard clinical examination. In group B, six animals, presented neurological pathologies associated with endogenous IgG production and, in group C four animals presented neurological diseases or symptoms not associated with intrathecal IgG production. Cerebrospinal fluid and serum samples were obtained from these animals. As expected, by using the indirect ELISAs proposed here, the IgG indexes obtained in healthy animals (A) were 0.371+/-0.252 (SD). In B and C, the values (3.002+/-1.897; 0.36+/-0.306, respectively), were in agreement with the pathologic conditions of the individuals in each group. Thus, the immunometric competition ELISA methods proposed here allow the discrimination of abnormal intrathecal IgG production, in a variety of inflammatory pathologic conditions of the central nervous system. 相似文献
23.
我国新一轮的税制改革即将开始,这将是继1994年分税制改革以来,我国又一次大的税收制度的调整,其目标是使我国的分税制体制更加完善,更加与市场经济相适应.税制改革中地方税制度的改革是十分关键的一部分,文中分析了当前我国地方税制度中存在的问题,并提出了一些构思性的设想. 相似文献
24.
25.
对家蚕育种亲本及其新品种性状数据档案实行信息化管理,可在家蚕育种和品种的种性维持过程中自动实现完整的信息采集、计算、调用、选择等功能。开发了一个基于B/S结构的家蚕育种与种性维持信息管理系统,主要包括品种管理、计划任务管理、饲育信息管理、蚕茧信息管理、选种信息管理、选优信息管理等功能模块。选种信息管理模块的运行过程是通过电子天平称量蚕茧质量,然后根据计算模型自动进行数据信息处理与统计分析实施选择。用户可以方便地通过网络访问该系统,实现家蚕新品种选育及种性维持工作的自动化。 相似文献
26.
Ellen Kaye Gehrke Ann Baldwin Patric M. Schiltz 《Journal of Equine Veterinary Science》2011,31(2):78-84
Although there has been a recent surge in using horses to treat mental and emotional human health issues, the consequences of horse-assisted interventions on the stress response of horses have not been well documented. Assessment of the autonomic nervous system and its regulation of cardiovascular function has been used as an indicator of acute and chronic stress in human beings and horses. Heart rate variability (HRV) is a noninvasive measurement that has been used to assess autonomic nervous system regulation of cardiovascular function. There is evidence to suggest that several factors including the genotype, behavior, environment, temperament, and nutritional status of the horse play a key role in the large inter-individual variations in basal HRV. The present study determined whether 24-hour HRV recordings in horses currently working in equine-assisted therapy (EAT) differ from those previously shown in Thoroughbred horses. Findings from the present study found that in contrast to previous studies in Thoroughbred horses, diurnal and nocturnal low frequency and high frequency powers were not significantly different in horses that are currently engaged in EAT. Future studies are needed to determine the short- and long-term consequences of horses participating in EAT programs. Findings from this study will provide the basis for the development of a physiological/behavioral assessment criteria to determine the consequences of EAT on the well-being of horses as well as to help EAT Centers to improve the beneficial effects of EAT in human beings. 相似文献
27.
Richard A. Rockar VMD Kenneth S. Drobatz DVM Frances S. Shofer PhD 《Journal of Veterinary Emergency and Critical Care》1994,4(2):77-83
An animal trauma triage (ATT) scoring system was devised to provide stratification of veterinary trauma patient populations based upon severity of injury. A retrospective population of 101 trauma patients and a prospective population of 88 patients were used to evaluate the predictive power of the ATT scoring system for survival seven days after initial presentation of the emergency service. In Both groups, the mean ATT score for survivors was significantly lower than the mean ATT score for non-survivors. In a logistic regression mode, the ATT score was found to be a significant predictor of the likelihood of survival seven days after initial presentation for both populartions. Each point increase in the ATT score resulted in a 2.3–2.6 times decreased likelihood of survival. The ATT scoring system is a useful objective classification scheme for predicting the likelihood to survive a traumatic incident and can serve as prototype for severity of injuroy scoring systems for the veterinary trauma patient. 相似文献
28.
29.
30.