全文获取类型
收费全文 | 27662篇 |
免费 | 846篇 |
国内免费 | 111篇 |
学科分类
农业科学 | 28619篇 |
出版年
2024年 | 19篇 |
2023年 | 104篇 |
2022年 | 182篇 |
2021年 | 345篇 |
2020年 | 363篇 |
2019年 | 343篇 |
2018年 | 3079篇 |
2017年 | 3080篇 |
2016年 | 1680篇 |
2015年 | 509篇 |
2014年 | 528篇 |
2013年 | 794篇 |
2012年 | 1683篇 |
2011年 | 2912篇 |
2010年 | 2573篇 |
2009年 | 1663篇 |
2008年 | 1934篇 |
2007年 | 2199篇 |
2006年 | 576篇 |
2005年 | 634篇 |
2004年 | 553篇 |
2003年 | 576篇 |
2002年 | 393篇 |
2001年 | 244篇 |
2000年 | 278篇 |
1999年 | 206篇 |
1998年 | 57篇 |
1997年 | 62篇 |
1996年 | 41篇 |
1995年 | 38篇 |
1994年 | 23篇 |
1993年 | 36篇 |
1992年 | 72篇 |
1991年 | 47篇 |
1990年 | 56篇 |
1989年 | 59篇 |
1988年 | 51篇 |
1987年 | 48篇 |
1986年 | 49篇 |
1985年 | 55篇 |
1984年 | 41篇 |
1983年 | 36篇 |
1982年 | 21篇 |
1979年 | 34篇 |
1978年 | 32篇 |
1977年 | 33篇 |
1974年 | 26篇 |
1973年 | 47篇 |
1972年 | 36篇 |
1971年 | 29篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
B Hofírek P Horín M Granátová M Machatková J Franz I Svoboda J Blecha 《Veterinární medicína》1986,31(3):129-140
A trial was performed with heifers at the age of six to seven months. The animals were experimentally infected with the lymphocytes of a virus-productive donor. Infection was produced in all the nine cases, as demonstrated by means of the positive syncytial test. As indicated by the results of the trial, the antibodies to the enzootic bovine leucosis virus (BLV) were produced soon after experimental infection. A high sensitivity of the serum-neutralization test and the ELISA method was demonstrated in this connection: by these methods, the antibodies were identified already two to three weeks after experimental infection whereas by the immunodiffusion test they could be detected only after five weeks. Twenty-four animals were exposed to natural contact infection. Within 270 days of the trial, the disease after contact was recorded only in one heifer out of the four that were in close contact with the experimentally infected animals. In this case, as compared with experimental infection, the antibodies were produced much later--after 85 to 93 days. Leucosis was recorded in none of the remaining animals. The reasons why such a favourable result was obtained were the thorough disinfection of the stables after blood collections and the strict observance of the aseptic conditions. The results of experimental infection in three cows were identical with those obtained in young cattle. In the experimentally infected dairy cows, antibodies in milk were determined by the ELISA method. As found, in milk the antibodies to BLV appear two to three weeks later than they do in serum. The ELISA method of BLV antibody detection can be used for the identification of infected animals in herds where enzootic bovine leucosis occurs. 相似文献
2.
The state of mucus synthesis in the goblet cells of the small intestine was studied in conventional piglets infected with a dose of 200,000 oocytes of the coccidium Isospora suis the first and fifth day after parturition. The synthesis of mucus and its chemical characteristics undergo significant changes during the third and fourth day after infection. The activity of acid and neutral mucous substances declines; their level and the physiological synthetic function of goblet cells begin to return to the normal during the period starting on the eight to tenth day after infection. However, there were no fully functioning goblet cells in the broken numerical ratio even at the end of the period of investigation, i.e. the 13th day after infection. The thin surface layer of mucus remained almost unchanged within the whole extent of the small intestine parts studied. 相似文献
3.
The fertility of male coypu sperm following seminal vesicle extirpation was investigated using the penetration test into the egg of Syrian golden hamster (Mesocricetus auratus). Ejaculates were obtained from five males by means of electro-ejaculation under halothane narcosis. The results of the zona-free hamster eggs (ZFHE) penetration test showed that the ejaculates of all the surgically treated coypu males were fertile and that ZFHE value fluctuated from 54 to 76.6%. The results obtained in experiments with natural mating revealed that the extirpation of male coypu seminal vesicles did not affect their fertility. In total 47 foetuses were found post mortem in ten coypu females covered by surgically treated males, which on average represented 4.7 foetuses per female. 相似文献
4.
Bacillary rickettsia-like organisms (BRLO) were found in the tick Dermacentor marginatus. They are gram-negative and differ from common bacteria and reckettsiae both in the cultivation conditions and morphology. BRLO are non-pathogenic for ticks and guinea pigs. In our studies they were isolated on half-engorged females of D. marginatus, on which they are still maintained. 相似文献
5.
6.
Nataa Mehle Maja Kova
Nataa Petrovi
Marua Pompe Novak pela Baebler Hana Kre
i
Stres Kristina Gruden Maja Ravnikar 《Physiological and Molecular Plant Pathology》2004,64(6):19
The aim of this work was to correlate the appearance of the symptoms, multiplication and spread of virus after mechanical inoculation of potato (Solanum tuberosum L.) cultivars showing different levels of susceptibility and sensitivity to Potato virus YNTN (PVYNTN). The potato cultivars used were the resistant cultivar Sante and susceptible cultivars Igor, Pentland squire and Désirée. The spread of the virus PVYNTN in infected plants was monitored using different methods: DAS-ELISA, tissue printing, immuno-serological electron microscopy and real-time PCR. In all three susceptible cultivars, the virus was detected in the inoculated leaves 4–5 days after inoculation. From there virus spread rapidly, first into the stem, then more or less simultaneously to the upper leaves and roots. Real-time PCR was shown to be very sensitive and enabled viral RNA to be detected in non-inoculated leaves of susceptible cultivar Igor earlier than other methods. Therefore, for exact studies of plant–virus interaction, a combination of methods which detect viruses on the basis of their different properties (coat protein, morphology or RNA) should be used to monitor the spread of viruses. 相似文献
7.
A. L. Echemendía P. L. Ramos L. Díaz R. Peral A. Fuentes M. Pujol G. González 《Plant pathology》2004,53(2):234-234
8.
Fracture of the medial intercondylar eminence of the tibia in horses treated by arthroscopic fragment removal (21 horses) 下载免费PDF全文
9.
Azarpajouh S. Marchewka J. Segura Correa J. C. Calderón Díaz J. A. 《Tropical animal health and production》2018,50(6):1343-1348
Tropical Animal Health and Production - The objective of this study was to compare hoof anatomy, hoof growth pattern, and hoof weight-bearing surface of six different Iranian sheep breeds to... 相似文献
10.
Eric Lim Teik Chung Michael Predith Frisco Nobilly Anjas Asmara Samsudin Faez Firdaus Abdullah Jesse Teck Chwen Loh 《Tropical animal health and production》2018,50(8):1727-1732
Brachiaria decumbens is an extremely productive tropical grass due to its aggressive growth habit and its adaptation to a varied range of soil types and environments. As a result of the vast availability, treated B. decumbens demonstrates as a promising local material that could be utilised as an improved diet for sheep and goats. Despite the fact that the grass significantly increases weight gains in grazing farm animals, there were many reports of general ill-thrift and sporadic outbreaks of photosensitivity in livestock due to the toxic compound of steroidal saponin found in B. decumbens. Ensiling and haymaking were found to be effective in removing toxin and undesirable compounds in the grass. Biological treatments using urea, activated charcoal, polyethylene glycol, and effective microorganisms were found to be useful in anti-nutritional factor deactivation and improving the nutritive values of feedstuffs. Besides, oral administration of phenobarbitone showed some degree of protection in sheep that fed on B. decumbens pasture. In this review, we aim to determine the effect of B. decumbens toxicity and possible treatment methods on the grass to be used as an improved diet for small ruminant. 相似文献