全文获取类型
收费全文 | 3339篇 |
免费 | 139篇 |
国内免费 | 3篇 |
专业分类
林业 | 239篇 |
农学 | 481篇 |
基础科学 | 87篇 |
861篇 | |
综合类 | 87篇 |
农作物 | 272篇 |
水产渔业 | 72篇 |
畜牧兽医 | 996篇 |
园艺 | 99篇 |
植物保护 | 287篇 |
出版年
2023年 | 23篇 |
2022年 | 39篇 |
2021年 | 51篇 |
2020年 | 87篇 |
2019年 | 88篇 |
2018年 | 121篇 |
2017年 | 139篇 |
2016年 | 108篇 |
2015年 | 83篇 |
2014年 | 94篇 |
2013年 | 300篇 |
2012年 | 141篇 |
2011年 | 161篇 |
2010年 | 127篇 |
2009年 | 113篇 |
2008年 | 116篇 |
2007年 | 141篇 |
2006年 | 146篇 |
2005年 | 113篇 |
2004年 | 74篇 |
2003年 | 79篇 |
2002年 | 74篇 |
2001年 | 57篇 |
2000年 | 53篇 |
1999年 | 55篇 |
1998年 | 42篇 |
1997年 | 44篇 |
1996年 | 35篇 |
1995年 | 34篇 |
1994年 | 29篇 |
1993年 | 28篇 |
1992年 | 30篇 |
1991年 | 36篇 |
1990年 | 34篇 |
1989年 | 39篇 |
1988年 | 47篇 |
1987年 | 34篇 |
1986年 | 29篇 |
1985年 | 25篇 |
1984年 | 25篇 |
1983年 | 26篇 |
1982年 | 22篇 |
1980年 | 34篇 |
1979年 | 37篇 |
1978年 | 20篇 |
1976年 | 20篇 |
1971年 | 20篇 |
1970年 | 37篇 |
1969年 | 24篇 |
1968年 | 23篇 |
排序方式: 共有3481条查询结果,搜索用时 15 毫秒
51.
52.
Disseminated histoplasmosis and disseminated intravascular coagulopathy were diagnosed in a 7 mo old, female spayed mixed-breed dog. The dog improved transiently with supportive care, but deteriorated shortly after initiation of antifungal therapy. The dog was subsequently euthanized. At necropsy, marked granulomatous vasculitis was identified in all affected organs. The tunicae and laminae of the arteries and arterioles were obscured by epithelioid macrophages and multinucleated giant cells admixed with necrotic material. Intracytoplasmic yeast were present within some of these macrophages. To the authors' knowledge, this is the first reported case of granulomatous vasculitis associated with Histoplasma capsulatum in a dog. 相似文献
53.
54.
In vitro evaluation of a simulated pneumoperitoneum environment using carbon dioxide on canine transitional cell carcinoma 下载免费PDF全文
55.
56.
57.
58.
Comparative Expression Analysis of Gametogenesis‐Associated Genes in Foetal and Adult Bubaline (Bubalus bubalis) Ovaries and Testes 下载免费PDF全文
SM Shah N Saini S Ashraf M Zandi MK Singh RS Manik SK Singla P Palta MS Chauhan 《Reproduction in domestic animals》2015,50(3):365-377
This study was conducted to identify and analyse the expression of gametogenesis‐associated genes and proteins in foetal and adult buffalo gonads of both the sexes. Relative quantification of the genes was determined by qPCR and Western blotting. Immunohistochemistry was also performed for various gametogenesis‐associated proteins in foetal and adult gonads of both the sexes. We observed significantly (p < 0.05) increased expression of primordial germ cell‐specific, meiotic as well as genes associated with oocyte maturation and development in foetal ovaries as compared to the adult ones. However, significantly (p < 0.05) increased expression of proteins associated with oocyte maturation like GDF9 and ZP4 was found in adult ovaries, indicating temporal regulation of mRNA translation during oogenesis. Meiotic genes showed significantly (p < 0.05) increased expression in adult testes as compared to foetal testes and ovaries, indicating onset of meiosis at a later stage in spermatogenesis. In general, the expression of primordial germ cell‐associated as well as meiotic genes was higher in adult testes, indicating the increased biological activity in the organ. Immunohistochemistry revealed localized expression of gametogenesis‐associated proteins in ovarian follicles and seminiferous tubules of testes, while the surrounding somatic tissues were devoid of these proteins. The study gives an understanding of the sequential and temporal events of gene expression as well as mRNA translation during male and female gametogenesis. It could also be concluded that follicles and seminiferous tubules are the functional units of the female and male gonads, respectively, and their function could be enhanced by appropriate chemical and genetic intervention of the somatic tissue immediately surrounding them. This assumes importance in the context that buffalo attains sexual maturity at an older age of 2–3 years and have smaller ovaries with lesser number of primordial follicles in comparison with cattle, which is suggested to be the main reason of their poor breeding performance. 相似文献
59.
Toxicological effects and recovery of the corneal epithelium in Cyprinus carpio communis Linn. exposed to monocrotophos: an scanning electron microscope study 下载免费PDF全文
Ravneet Kaur Uppal Mohinder Singh Johal Madan Lal Sharma 《Veterinary ophthalmology》2015,18(3):214-220
This study was conducted based on the evidence of fish habitats in North India being affected by organophosphate pesticides draining from agricultural fields into bodies of water, especially during the rainy season. Various tissues of fish such as scales, gills ovaries, kidney, and liver have been studied from the toxicological point of view, but the toxicological effects of aquatic pollutants on fish cornea have not been investigated to date. We conducted comparative toxicological studies on the cornea of Cyprinus carpio communis using two sublethal (0.038 and 0.126 ppm) concentrations of monocrotophos pesticide for 30 days. Corneas from all the groups were evaluated by a scanning electron microscope. The fish exposed to the monocrotophos pesticide developed corneal necrosis due to the formation of crystalloid‐like structures, thinning and shrinkage of microridges on the corneal epithelium. After 30 days, fish from the monocrotophos‐treated tank were transferred to normal environmental conditions. After 60 days under natural condition, epithelial cells did not fully recover. In conclusion, exposure to monocrotophos induces irreversible changes in the cornea of C. carpio communis. As fish and mammalian visual systems share many similarities, the reported finding may offer useful insights for further toxicological and ophthalmological studies in humans. 相似文献
60.
A. K. Dixit G. Das Pooja Dixit A. P. Singh N. K. Kumbhakar M. Sankar R. L. Sharma 《Tropical animal health and production》2017,49(7):1471-1478
Current status of resistance to benzimidazole (BZ) group of anthelmintic drugs against caprine nematodes in Central India at Amanala goat farm, Jabalpur, Madhya Pradesh (M. P.), was systematically investigated using faecal egg count reduction (FECR) test and egg hatch test (EHT). Besides, allele-specific PCR (AS-PCR) was deployed to ascertain the susceptible genotype (alleles) especially of the Haemonchus contortus. Randomly selected 30 goats, irrespective of age and sex, were divided into three groups of 10 each, to serve as treated and untreated controls. It was ensured that the animals were not administered with an anthelmintic drug for the past 3 months prior to undertaking the study, and faecal egg counts were estimated. FECR test evidenced fenbendazole resistance by partial elimination (24.90%) copro-egg counts in the treated group of animals vis-à-vis controls with a lower confidence interval of ?26%. Further, EHT revealed ED-50 value of 0.335 μg of thiabendazole/ml, confirming benzimidazole resistance in the animals of that farm. AS-PCR showed that 62% of H. contortus larvae were homozygous resistant (rr), 24% heterozygous (rS) and 14% homozygous susceptible (SS). The genotypic frequencies of three genotypes (rr, rS and SS) were significantly (P < 0.01) different. The prevalence of benzimidazole resistance allele (r) was also significantly (P < 0.01) higher (74%) as compared to susceptible allele (S) (26%). The resistance to benzimidazole has been discussed while emphasizing improved managemental practices designed to reduce exposure of the goat population to parasites, minimize frequency of anthelmintic use at optimum dose and rotational use of different chemical groups of medicines with different mode of action, so as to overcome and combat the upcoming problem in the field. 相似文献