全文获取类型
收费全文 | 23032篇 |
免费 | 737篇 |
国内免费 | 23篇 |
专业分类
林业 | 1302篇 |
农学 | 751篇 |
基础科学 | 180篇 |
3839篇 | |
综合类 | 3372篇 |
农作物 | 1152篇 |
水产渔业 | 1319篇 |
畜牧兽医 | 10180篇 |
园艺 | 363篇 |
植物保护 | 1334篇 |
出版年
2021年 | 254篇 |
2020年 | 295篇 |
2019年 | 336篇 |
2018年 | 407篇 |
2017年 | 486篇 |
2016年 | 395篇 |
2015年 | 287篇 |
2014年 | 455篇 |
2013年 | 920篇 |
2012年 | 806篇 |
2011年 | 1002篇 |
2010年 | 669篇 |
2009年 | 604篇 |
2008年 | 964篇 |
2007年 | 887篇 |
2006年 | 867篇 |
2005年 | 806篇 |
2004年 | 733篇 |
2003年 | 718篇 |
2002年 | 670篇 |
2001年 | 561篇 |
2000年 | 543篇 |
1999年 | 458篇 |
1998年 | 244篇 |
1997年 | 255篇 |
1996年 | 202篇 |
1995年 | 235篇 |
1994年 | 179篇 |
1993年 | 207篇 |
1992年 | 315篇 |
1991年 | 348篇 |
1990年 | 345篇 |
1989年 | 355篇 |
1988年 | 323篇 |
1987年 | 271篇 |
1986年 | 314篇 |
1985年 | 284篇 |
1984年 | 231篇 |
1983年 | 241篇 |
1979年 | 263篇 |
1978年 | 183篇 |
1977年 | 172篇 |
1975年 | 180篇 |
1974年 | 249篇 |
1973年 | 232篇 |
1972年 | 264篇 |
1971年 | 236篇 |
1970年 | 212篇 |
1969年 | 196篇 |
1966年 | 170篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Acacia etbaica Schweinf. and Dichrostachys cinerea (L.) Wight et Arn. are among the common woody browse plants that naturally grow in many arid and semi-arid rangelands in sub Saharan Africa. An experiment was conducted to compare the voluntary dry matter intake, body weight gain, nitrogen balance, carcass composition and sensory attributes of goats supplemented with different levels of A. etbaica and D. cinerea fruits. Average initial body weight of the goats was 20.4 kg (± 0.8SE) and received one of the following fruit supplementation regimes for 120 days (on body weight basis, n = 4 goats per group): (1) Control, no supplement; (2) 0.5% of A. etbaica; (3) 0.5% of D. cinerea; (4) 1.0% of A. etbaica; (5) 1.0% of D. cinerea; (6) 1.5% of A. etbaica; (7) 1.5% of D. cinerea. All groups were allowed to graze/browse during the day. Compared to A. etbaica, D. cinerea fruits contained higher amounts of crude protein (182 vs 135 g/kg DM), metabolizable energy (11 vs 8.4 MJ/kg DM), and in vitro dry matter digestibility coefficient (0.7 vs 0.6). The concentrations of acid detergent fiber (ADF), sulphuric acid solubulized lignin, and tannin (soluble and condensed) were lower (P < 0.05) in D. cinerea than in A. etbaica fruits. A. etbaica fruits, however, contained higher amounts of Na, K, Fe, and Zn concentrations than D. cinerea fruits. Dry matter intake was markedly higher in supplemented groups than in the control group without supplement. Similarly, body weight gain in the control group was negative and lower (P < 0.05) than any of the supplemented groups. During the course of the experimental period (120 days) the group placed in the 1.5% D. cinerea fruit diet gained 2.6 kg whereas the control group lost 2.0 kg. Thus, the difference between these two groups was 4.6 kg, which suggests about 22.5% increment of the goats' initial body weight. N retention was negative for the control group and varied little among the remaining treatment groups. Dressing percent increased with increased level of either type of fruit supplement, the highest (51.8%) being achieved at the 1.5% D. cinerea level. There was no difference in bone tissue across treatment groups. D. cinerea fruit intake also resulted in juicy/watery flavor and tender carcass. D. cinerea fruits appeared to have no adverse effects when included at the highest level (1.5%) and could be collected and stored as dry season supplement to smallholder goats. This study shows that poor farmers can increase goat performance substantially through supplement feeding with wild fruits. Areas in Ethiopia originally set aside for provision of ecological services and biodiversity protection can also be used for wild fruit production and feeding of small stock. The effect of increasing D. cinerea fruits above the 1.5% body weight level should be a focus of future investigation. Further work on deactivation mechanism of tannins is required for A. etbaica fruits included at levels higher than 1.0%. 相似文献
32.
33.
Hanley CS MacWilliams P Giles S Paré J 《The Canadian veterinary journal. La revue veterinaire canadienne》2006,47(10):1015-1017
A domestic ferret was presented for episodic regurgitation. Cytologic examination and culture of an enlarged submandibular lymph node revealed Cryptococcus neoformans variety grubii (serotype A). The ferret was successfully treated with itraconazole. This is the first documented case of Cryptococcus neoformans variety grubii in a ferret in the United States. 相似文献
34.
Verster RS Botha CJ Naidoo V Van Schalkwyk OL 《Journal of the South African Veterinary Association》2004,75(4):177-181
A survey of aldicarb poisoning in companion animals was conducted by posting questionnaires to all private practitioners in Gauteng Province, South Africa. The survey was designed to determine the percentage of aldicarb cases seen, treatment regimen, clinical signs observed, proposals for preventative actions and more effective treatments. Other questions included duration of treatment, survival rate, cost to clients, post mortem findings and reasons for poisonings. 相似文献
35.
36.
In a 7 year old female poodle an adrenocortical tumor was diagnosed on basis of laboratory and ultrasonographic examinations. One year after adrenalectomy, a relapse was diagnosed, at that time the suspicion of metastases in the liver arose for the first time. By treatment with Mitotane in a dose aiming at completely destroying the adrenal cortex, a complete disappearance of the tumor as well as a dramatic reduction of the size of the metastases could be achieved. 12 months after the begin of the chemotherapy, the dog is in good general condition. 相似文献
37.
A method is described for production of an equine anti-bovine leukocyte serum (EABLS). Leukocytes were harvested from the milk of cow's udders which had been irritated with endotoxin. The washed leukocytes as antigens were administered to 2 horses in a series of subcutaneous and intravenous injections. There was a variably progressive increase in total serum proteins and a decrease in albumin/blobulin ratios, but the most pronounced change was an increase in beta2-globulins. Accompanying these changes was an increase in the number of precipitin lines as shown by Ouchterlony analysis. Four old cows and 2 calves were intravenously given a 50- and 20-ml dose, respectively, of the EABLS. Two of the cows and 1 of the calves were given the EABLS which had been heated to 56 C for 30 minutes. Both calves and the 2 cows given heated EABLS and 1 cow given unheated EABLS developed marked neutropenia within the 1st hour. The 4th cow given unheated EABLS developed only slight neutropenia. It was concluded that there may be variation in the individual animal's susceptibility to the neutropenia-inducing activity of EABLS. 相似文献
38.
39.
Peter Irwin 《Australian veterinary journal》1994,71(4):128-128
Veterinary Virology, 2nd edition, FJ Fenner, EPJ Gibbs, FA
Murphy, R Roitt, MJ Studded and DO White, Russia. 相似文献
Murphy, R Roitt, MJ Studded and DO White, Russia. 相似文献
40.