全文获取类型
收费全文 | 24684篇 |
免费 | 546篇 |
国内免费 | 50篇 |
专业分类
林业 | 4100篇 |
农学 | 1675篇 |
基础科学 | 214篇 |
4201篇 | |
综合类 | 1314篇 |
农作物 | 2501篇 |
水产渔业 | 2416篇 |
畜牧兽医 | 5033篇 |
园艺 | 1224篇 |
植物保护 | 2602篇 |
出版年
2023年 | 83篇 |
2022年 | 149篇 |
2021年 | 284篇 |
2020年 | 263篇 |
2019年 | 339篇 |
2018年 | 2930篇 |
2017年 | 2922篇 |
2016年 | 1487篇 |
2015年 | 288篇 |
2014年 | 327篇 |
2013年 | 500篇 |
2012年 | 1260篇 |
2011年 | 2617篇 |
2010年 | 2330篇 |
2009年 | 1508篇 |
2008年 | 1714篇 |
2007年 | 1964篇 |
2006年 | 410篇 |
2005年 | 456篇 |
2004年 | 435篇 |
2003年 | 447篇 |
2002年 | 392篇 |
2001年 | 245篇 |
2000年 | 281篇 |
1999年 | 204篇 |
1998年 | 59篇 |
1997年 | 59篇 |
1996年 | 55篇 |
1995年 | 52篇 |
1994年 | 37篇 |
1993年 | 50篇 |
1992年 | 85篇 |
1991年 | 52篇 |
1990年 | 62篇 |
1989年 | 73篇 |
1988年 | 71篇 |
1987年 | 53篇 |
1986年 | 46篇 |
1985年 | 58篇 |
1984年 | 37篇 |
1983年 | 42篇 |
1982年 | 30篇 |
1980年 | 23篇 |
1979年 | 37篇 |
1978年 | 21篇 |
1977年 | 23篇 |
1974年 | 23篇 |
1973年 | 25篇 |
1972年 | 25篇 |
1970年 | 26篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Polymethylmethacrylate orbital implants with interconnecting channels. A retrospective study following enucleation in dogs and cats
下载免费PDF全文
![点击此处可从《Veterinary ophthalmology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
102.
103.
104.
105.
106.
107.
108.
Amália Turner Giannico Elaine Mayumi Ueno Gil Daniela Aparecida Ayres Garcia Marlos Gonçalves Sousa Tilde Rodrigues Froes 《Veterinary research communications》2016,40(1):11-19
The aim of this study was to develop regression models for correlation of canine fetal heart development with body size to characterize normal development or suggest cardiac anomalies. Twenty clinically healthy pregnant bitches, either brachycephalic and non-brachycephalic, were examined ultrasonographically. Transabdominal fetal echocardiography was conducted every 4 days from the beginning of cardiac chambers differentiation until parturition. Ten cardiac parameters were measured: length, width and diameter of the heart; heart area; left and right ventricular dimensions; left and right atrial dimensions; and aortic and pulmonary artery diameter. Femoral length, biparietal diameter and abdominal cross-sectional area were also recorded. Regression equations were developed for each parameter of fetal body size, and linear and logarithmic models were compared. The model with the highest correlation coefficient was chosen to produce equations to calculate relative dimensions based on the correlations. Only the left-ventricular chamber differed between the two racial groups. Biparietal diameter was the independent parameter that produced the highest correlation coefficient for the most fetal cardiac dimensions, although good correlations were also observed using femoral length and abdominal cross-sectional area. Heart width and heart diameter were used as surrogates of cardiac development, as these measurements showed the best statistical correlation. Quantitative evaluation of fetal cardiac structures can be used to monitor normal and abnormal cardiac development. 相似文献
109.
Chiara Gomiero Giulia Bertolutti Tiziana Martinello Nathalie Van Bruaene Sarah Y. Broeckx Marco Patruno Jan H. Spaas 《Veterinary research communications》2016,40(1):39-48
Tendons regenerate poorly due to a dense extracellular matrix and low cellularity. Cellular therapies aim to improve tendon repair using mesenchymal stem cells and tenocytes; however, a current limitation is the low proliferative potential of tenocytes in cases of severe trauma. The purpose of this study was to develop a method useful in veterinary medicine to improve the differentiation of Peripheral Blood equine mesenchymal stem cells (PB-MSCs) into tenocytes. PB-MSCs were used to study the effects of the addition of some growth factors (GFs) as TGFβ3 (transforming growth factor), EGF2 (Epidermal growth factor), bFGF2 (Fibroblast growth factor) and IGF-1 (insulin-like growth factor) in presence or without Low Level Laser Technology (LLLT) on the mRNA expression levels of genes important in the tenogenic induction as Early Growth Response Protein-1 (EGR1), Tenascin (TNC) and Decorin (DCN). The singular addition of GFs did not show any influence on the mRNA expression of tenogenic genes whereas the specific combinations that arrested cell proliferation in favour of differentiation were the following: bFGF2 + TGFβ3 and bFGF2 + TGFβ3 + LLLT. Indeed, the supplement of bFGF2 and TGFβ3 significantly upregulated the expression of Early Growth Response Protein-1 and Decorin, while the use of LLLT induced a significant increase of Tenascin C levels. In conclusion, the present study might furnish significant suggestions for developing an efficient approach for tenocyte induction since the external administration of bFGF2 and TGFβ3, along with LLLT, influences the differentiation of PB-MSCs towards the tenogenic fate. 相似文献
110.