全文获取类型
收费全文 | 24875篇 |
免费 | 1287篇 |
国内免费 | 10篇 |
专业分类
林业 | 877篇 |
农学 | 752篇 |
基础科学 | 154篇 |
3616篇 | |
综合类 | 3529篇 |
农作物 | 910篇 |
水产渔业 | 1339篇 |
畜牧兽医 | 13169篇 |
园艺 | 268篇 |
植物保护 | 1558篇 |
出版年
2019年 | 250篇 |
2018年 | 415篇 |
2017年 | 508篇 |
2016年 | 471篇 |
2015年 | 337篇 |
2014年 | 457篇 |
2013年 | 961篇 |
2012年 | 794篇 |
2011年 | 951篇 |
2010年 | 686篇 |
2009年 | 669篇 |
2008年 | 966篇 |
2007年 | 917篇 |
2006年 | 808篇 |
2005年 | 735篇 |
2004年 | 644篇 |
2003年 | 705篇 |
2002年 | 605篇 |
2001年 | 803篇 |
2000年 | 799篇 |
1999年 | 633篇 |
1998年 | 274篇 |
1997年 | 282篇 |
1995年 | 259篇 |
1994年 | 227篇 |
1993年 | 232篇 |
1992年 | 424篇 |
1991年 | 516篇 |
1990年 | 434篇 |
1989年 | 411篇 |
1988年 | 400篇 |
1987年 | 409篇 |
1986年 | 363篇 |
1985年 | 388篇 |
1984年 | 339篇 |
1983年 | 287篇 |
1982年 | 243篇 |
1979年 | 383篇 |
1978年 | 289篇 |
1977年 | 290篇 |
1976年 | 299篇 |
1975年 | 317篇 |
1974年 | 332篇 |
1973年 | 302篇 |
1972年 | 290篇 |
1971年 | 245篇 |
1969年 | 289篇 |
1968年 | 269篇 |
1967年 | 326篇 |
1966年 | 304篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
A. E. Joetzke K. A. Sterenczak N. Eberle S. Wagner J. T. Soller I. Nolte J. Bullerdiek H. Murua Escobar D. Simon 《Veterinary and comparative oncology》2010,8(2):87-95
Overexpression of high mobility group A (HMGA) genes was described as a prognostic marker in different human malignancies, but its role in canine haematopoietic malignancies was unknown so far. The objective of this study was to analyse HMGA1 and HMGA2 gene expression in lymph nodes of canine lymphoma patients. The expression of HMGA1 and HMGA2 was analysed in lymph node samples of 23 dogs with lymphoma and three control dogs using relative quantitative real‐time RT‐PCR. Relative quantity of HMGA1 was significantly higher in dogs with lymphoma compared with reference samples. HMGA2 expression did not differ between lymphoma and control dogs. With the exception of immunophenotype, comparison of disease parameters did not display any differences in HMGA1 and HMGA2 expression. The present findings indicate a role of HMGA genes in canine lymphoma. This study represents the basis for future veterinary and comparative studies dealing with their diagnostic, prognostic and therapeutic values. 相似文献
104.
I. Srugo O. Chai D. Yaakov L. Sharon M. H. Shamir 《The Journal of small animal practice》2010,51(8):447-450
Thoracolumbar disc herniation was diagnosed in a two-year-old ferret using a myelogram followed by a computed tomography scan. The ferret was paraplegic with no control over urination and defecation. Conservative treatment that included cage rest and passive range of motion exercises for three weeks followed by extensive physiotherapy and hydrotherapy resulted in full recovery two months after the onset of treatment. Although intervertebral disc disease has been reported previously in four ferrets, this is the first report in which a postmyelogram computed tomography was used to demonstrate the herniated disc, and physiotherapy was used as principal treatment modality. 相似文献
105.
Cystic alterations of the canine endometrium compromise reproduction and fertility of the bitch and may lead to life-threatening diseases, such as pyometra. Even without clinical evidence, reduction of the uterine lumen by cysts implicates disturbances during migration, nidation and development of the embryo. Several studies point to the high variability of morphology of uterine endometrial cysts but they lack detailed analyses of alterations. In the present study, immunohistochemistry was used to investigate the expression of steroid hormone receptors (oestrogen, progesterone), proliferation activity, inflammation and infection in the cystic affected tissue regions in contrast to the normal endometrium. Oestrogen receptor expression showed a high density of receptors throughout the surface epithelial cells, crypt epithelial cells, glandular epithelial cells and stromal cells of the normal endometrium as well as the cystic affected regions. Proliferation in the cysts was verified in the middle and basal cells of the crypts. Neither in the endometrium nor in the cysts inflammatory processes or evidence of infection could be detected. Furthermore, lectin histochemistry and electron microscopic methods showed that lectin binding patterns and cell morphology of internal epithelial lining and surface epithelium of the cysts can be used to characterize and distinguish different types of cystic alterations. Analogies between epithelial cells of the glandular chambers of the canine placenta and the cystic cellular morphology, steroid hormone receptor distribution as well as lectin binding patterns of the endometrial cysts, as observed in this study, suggest to introduce the term 'pseudo-placentational endometrial cysts'. 相似文献
106.
The morphology of Onchocerca lupi, responsible for canine ocular onchocercosis, is unique within the genus. Earlier analyses of the 5S ribosomal RNA gene spacer region sequence of the parasite and the 16S ribosomal RNA gene sequence of its Wolbachia endosymbiotic bacteria (Rickettsiales) supported the morphological and biological arguments that O. lupi is a distinct species. However, the exact phylogenetic position of O. lupi and its endosymbiont could not be unambiguously determined. Herein we report analyses based on the mitochondrial cytochrome oxidase I (COI) gene of the filarial species and the Wolbachia surface protein (wsp) and the bacterial cell-cycle ftsZ genes of their wolbachiae. Our results indicate that O. lupi separated from other Onchocerca spp. early in evolution. This is in line with the previous morphological analysis demonstrating that O. lupi is an atypical Onchocerca species showing both primitive and evolved characters. The phylogenetic trees generated for the COI sequences of filariae and the wsp and ftsZ sequences of their wolbachiae were congruent with each other, which supports the hypothesis that nematodes and their Wolbachia endobacteria share a long co-evolutionary history. 相似文献
107.
An unusual case of entropion, corneal ulcer and corneal haemorrhages in a one‐humped camel (Camelus dromedaries) is described. The most prominent clinical findings were entropion of both eyelids, severe blephrospasm, epiphora, conjunctivitis, conjunctival oedema, mucopurulent conjunctival discharges, hyperaemia, lacrimation and photophobia. Corneal ulcers and corneal haemorrhages were also observed. 相似文献
108.
D. J. STEWART B. L. CLARK J. E. PETERSON D. L. EMERY E. F. SMITH† D. A. GRIFFITHS† I. J. O'DONNELL‡ 《Australian veterinary journal》1985,62(5):153-159
A highly purified pilus vaccine prepared from cells of Bacteroides nodosus strain 198 provided a high level of protection against homologous challenge and small, not statistically significant, levels of protection against challenge with 4 other strains each from different serogroups. In a second experiment, a partially purified pilus vaccine from strain 198 induced significant immunity to 1 of 4 heterologous strains which were different from those used in the first experiment. In a third experiment a strain 198 whole cell vaccine produced significant immunity against 3 of 6 heterologous strains used in the first 2 experiments. There was no obvious relationship between the colony type, degree of piliation and level of cross-protection obtained against a particular strain. The results provide further evidence that immunogens associated with, but distinct from, the pilus are involved in cross-protection and that cross-protective antigens are common to some, but not all, strains. 相似文献
109.
H B Gelberg J F Zachary J I Everitt R C Jensen D L Smetzer 《Journal of the American Veterinary Medical Association》1985,187(12):1354-1356
We reviewed case records, necropsy reports, and histologic sections from 25 Thoroughbred racehorses that died suddenly at 3 Chicago racetracks. These were young horses ranging in age from 2 to 5 years. There were more females (n = 16) than males (n = 9), and the incidence of death increased slightly in the spring and summer. Twenty-one of the 25 horses died while racing or training. Only 8 of the 25 horses (32%) had lesions sufficient to account for the death. In 6 of those 8 cases, death was caused by massive thoracic or abdominal hemorrhage. The site or nature of the vascular defect in these cases could not be determined. One horse died of severe preexisting pulmonary disease, and one died of encephalitis and cardiac papillary muscle fibrosis. The cause of death was undetermined in 17 horses (68%). Nearly all horses had pulmonary edema, congestion, and/or hemorrhage. We postulate that these unexplained deaths were a result of exercise-induced acute cardiovascular failure. 相似文献
110.