全文获取类型
收费全文 | 26682篇 |
免费 | 4530篇 |
国内免费 | 645篇 |
专业分类
林业 | 2067篇 |
农学 | 1493篇 |
基础科学 | 401篇 |
5401篇 | |
综合类 | 3874篇 |
农作物 | 1161篇 |
水产渔业 | 3635篇 |
畜牧兽医 | 10228篇 |
园艺 | 846篇 |
植物保护 | 2751篇 |
出版年
2024年 | 48篇 |
2023年 | 288篇 |
2022年 | 504篇 |
2021年 | 852篇 |
2020年 | 1141篇 |
2019年 | 1583篇 |
2018年 | 1670篇 |
2017年 | 1790篇 |
2016年 | 1694篇 |
2015年 | 1608篇 |
2014年 | 1669篇 |
2013年 | 2207篇 |
2012年 | 2146篇 |
2011年 | 2119篇 |
2010年 | 1701篇 |
2009年 | 1244篇 |
2008年 | 1528篇 |
2007年 | 1275篇 |
2006年 | 1060篇 |
2005年 | 1004篇 |
2004年 | 819篇 |
2003年 | 721篇 |
2002年 | 639篇 |
2001年 | 397篇 |
2000年 | 399篇 |
1999年 | 256篇 |
1998年 | 96篇 |
1997年 | 83篇 |
1996年 | 63篇 |
1995年 | 77篇 |
1994年 | 55篇 |
1993年 | 50篇 |
1992年 | 91篇 |
1991年 | 77篇 |
1990年 | 70篇 |
1989年 | 63篇 |
1988年 | 59篇 |
1987年 | 50篇 |
1986年 | 55篇 |
1985年 | 53篇 |
1984年 | 47篇 |
1983年 | 38篇 |
1979年 | 37篇 |
1978年 | 27篇 |
1974年 | 28篇 |
1972年 | 23篇 |
1971年 | 27篇 |
1970年 | 31篇 |
1969年 | 25篇 |
1968年 | 27篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
Biochemical variables from Holstein‐Friesian calves older than one week are comparable to those obtained from adult animals of stable metabolic status on the same farm 下载免费PDF全文
994.
Traditional veterinary anatomical models describe the branches of the caudal gluteal artery as the iliolumbar, cranial gluteal, lateral caudal, satellite of the ischiatic nerve and dorsal perineal arteries. However, some classical veterinary anatomy textbooks often indicate variations the general organization of the arterial tree, without giving any pattern of origin or illustrations of the different branching. The aim of this study was to investigate the presumptive variability of the caudal gluteal artery. Two hundred and thirty‐two pelvic halves from 116 adult dogs were examined. Twelve anatomical variations were found, nine occurring in more than 5% of the dogs, and three in <5%. A ‘long‐type’ internal iliac artery, which means short caudal gluteal and internal pudendal arteries, was identified, while a ‘perineal trunk’ was observed as an interesting arterial variation. If the caudal segment alone is taken into consideration, identical vascular patterns in both hemi‐pelvises are found in 17% of the dogs. Significant statistical correlation was found for four different types of anatomic variations and gender, two types of variations and body size, one type of variation for body side and one type of variation for head shape. 相似文献
995.
Plastic hematocrit tubes (PHTs) are convenient tools for electron microscopy (EM) of peripheral blood buffy coats, and the PHT‐EM technique is expected to be a practical method for veterinary clinical medicine. In this study, fixatives composed of various concentrations of sucrose, glutaraldehyde, and phosphate buffer (PB) were tested for preparing canine and feline buffy coats. The highest quality images were obtained using a fixative consisting of 2.5% glutaraldehyde in 0.1 m PB, and it was concluded that this method allows clinicians who are inexperienced in histological techniques can conveniently transport buffy coat samples to diagnostic laboratories for analysis by EM. 相似文献
996.
Distribution of Galanin and Galanin Receptor 2 in the Pre‐optic Area of the Female Guinea Pig 下载免费PDF全文
B. Hermanowicz K. Bogus‐Nowakowska M. Równiak W. Żakowski B. Wasilewska J. Najdzion A. Robak 《Anatomia, histologia, embryologia》2015,44(4):308-316
This study describes the distribution of galanin (Gal) and galanin receptor 2 (GalR2) in the pre‐optic area (POA) of the female guinea pig. Frozen sections were undergone for a routine immunofluorescence labelling. Gal and GalR2 display immunoreactivity in all parts of the pre‐optic area. Gal shows reactivity both in perikarya and fibres, whereas GalR2 was observed only in perikarya. Gal‐ and GalR2‐immunoreactive (‐ir) perikarya were the most numerous in the medial pre‐optic area (MPA) with the highest reactivity in its dorsal part. In the median pre‐optic nucleus (MPN) and periventricular pre‐optic nucleus (PPN), only single Gal‐ and GalR2‐ir neurons were observed. The highest density of Gal‐ir fibres was revealed in the PPN and the lowest in the lateral pre‐optic area (LPA). The results of this study indicate that the distribution pattern of Gal containing neurons overlaps well with the distribution pattern of GalR2‐positive neurons, especially in the MPA. This may suggest GalR2‐dependent activity in this brain region. 相似文献
997.
L. Gatel D. Rault K. Chalvet‐Monfray J. Saunders S. Buff 《Anatomia, histologia, embryologia》2015,44(4):241-246
This study investigated the prediction of parturition in queens, as well as the effects of the queens' age and weight and the litter size on the accuracy of the prediction. A prospective study was performed in 24 purebred queens of 11 different breeds, all in normal body condition, using radiographic and ultrasonographic measurements of foetal femoral length (FL) and biparietal diameter (BPD) of f?tal skull that apply to different breeds. Pregnant queens with aborted or malformed foetuses were excluded. The examinations were performed up to three times during the second half of pregnancy; litter size was obtained with radiography, and FL and BPD measurements were taken of each foetus using both radiography and ultrasonography. The maximal FL and the transversal BPD were recorded for each foetus. Radiography showed the number of foetuses accurately but did not allow accurate prediction of time of parturition. However, ultrasonography did establish the best predictive model according to the data with the FL. This model corresponded to the formula Y = 37.864 ? 0.193 × FL + 1.227 × W ? 0.615 × LS ? 0.832 × A using the FL (10?1 mm), litter size (LS, number of foetuses per queen) and maternal parameters (weight (W, kg) and age (A, years)). Time to parturition correlated positively with the queen's weight and negatively with her age (P < 0.01). The ultrasonographic FL associated with pregnancy and maternal factors appeared to be an accurate model to predict parturition . 相似文献
998.
999.
1000.