首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   5715篇
  免费   284篇
  国内免费   542篇
林业   711篇
农学   797篇
基础科学   346篇
  836篇
综合类   1514篇
农作物   463篇
水产渔业   229篇
畜牧兽医   1139篇
园艺   164篇
植物保护   342篇
  2024年   11篇
  2023年   63篇
  2022年   170篇
  2021年   232篇
  2020年   178篇
  2019年   185篇
  2018年   142篇
  2017年   188篇
  2016年   219篇
  2015年   241篇
  2014年   273篇
  2013年   337篇
  2012年   380篇
  2011年   386篇
  2010年   372篇
  2009年   315篇
  2008年   273篇
  2007年   333篇
  2006年   315篇
  2005年   243篇
  2004年   156篇
  2003年   141篇
  2002年   172篇
  2001年   148篇
  2000年   136篇
  1999年   124篇
  1998年   106篇
  1997年   95篇
  1996年   92篇
  1995年   82篇
  1994年   77篇
  1993年   73篇
  1992年   61篇
  1991年   75篇
  1990年   37篇
  1989年   32篇
  1988年   27篇
  1987年   12篇
  1986年   6篇
  1985年   6篇
  1984年   5篇
  1983年   4篇
  1982年   4篇
  1981年   5篇
  1980年   3篇
  1979年   2篇
  1978年   1篇
  1972年   1篇
  1971年   1篇
  1963年   1篇
排序方式: 共有6541条查询结果,搜索用时 0 毫秒
41.
Abstract: An 18-month-old male Doberman Pinscher was referred to the Veterinary Medical Teaching Hospital of the College of Veterinary Medicine for an erythemic nodular mass on the right forelimb. The mass was diagnosed as cutaneous lymphoma, based on cytologic examination of a mass aspirate and histopathology. Using immunohistochemistry the neoplastic cells were positive for CD3 but negative for CD79a, E-cadherin, and pancytokeratin, confirming their origin as T lymphocytes. No tumor recurrence was noted 18 months after surgery. To our knowledge, this is the first report of a solitary nodular form of cutaneous lymphoma in a young dog.  相似文献   
42.
对四川省阿坝州若尔盖县鼠荒地采取“害鼠控制+围栏封育+禁牧+整地施肥+草种补播”的综合治理措施,并于治理前(2017年)和治理后(2018—2020年),采用堵洞开洞法调查高原鼠兔(Ochotona curzoniae)有效洞口数量,利用植物群落调查法调查植物群落结构和植物物种多样性,分析治理后高原鼠兔相对种群密度、植物群落结构和植物物种多样性的变化。结果显示:治理后第1年、第2年和第3年,高原鼠兔有效洞口数分别减少了90.4%、90.6%和64.7%;植物种类分别增加了60.0%、40.0%和35.0%;植被平均高度分别增加了437.3%、441.0%和442.2%;植被盖度增幅分别为153.6%、152.0%和140.8%;平均鲜草产量分别达到15 862.5、15 007.5和12 547.5 kg/hm2,比治理前分别增加了272.2%、252.0%和194.3%;丰富度指数、Shannon-Wiener指数、Simpson指数和Pielou指数在治理1年后分别增加了60.0%、26.0%、11.6%和8.9%,治理2年后分别增加了40.0%、27.6%、...  相似文献   
43.
Three dead dogs were brought to the College of Veterinary Medicine, Kyungpook National University for study. Clinically, all the dogs showed emaciation, anorexia, depression, hemorrhagic vomiting and diarrhea for 7~10 days before death. All the clinical signs were first noted for about one month after feeding the dogs with commercial diets. At necropsy, all 3 dogs had severe renal damage with the same green-yellowish colored nephroliths in the renal pelvis. They also showed systemic hemorrhage and calcification of several organs, which might have been induced by uremia. Microscopically, necrosis, calcification and calculi were detected in the renal tubules, and especially in the proximal convoluted tubules and collecting ducts of the kidney. These findings were supportive of a mycotoxic effect, and especially on their kidneys. However, the precise cause of the toxic effect in these cases of canine renal failure could not be determined.  相似文献   
44.
45.
Su  Q. L.  Song  H. Q.  Lin  R. Q.  Yuan  Z. G.  Yang  J. F.  Zhao  G. H.  Huang  W. Y.  Zhu  Xing Quan 《Tropical animal health and production》2010,42(8):1805-1808
Candidatus Mycoplasma haemobos” is a hemoplasma species found in cattle and has been recently reported in Switzerland and Japan. In this study, “Candidatus Mycoplasma haemobos” was shown to occur in cattle and buffalo in tropical China by PCR amplification and sequence analysis of the 16S rRNA gene from blood samples. Based on the 16S rDNA sequence, a specific PCR assay was developed. Occurrence of “Candidatus Mycoplasma haemobos” in cattle and buffalo in Guangxi, China, was determined by examining 25 buffalo blood samples, 12 yellow cattle blood samples and 42 dairy cow blood samples. The results showed that 32% (8/25) of buffalo, 41.7% (5/12) of yellow cattle, and 14.3% (6/42) of dairy cows were positive for “Candidatus Mycoplasma haemobos”, respectively. Direct sequencing of representative PCR products confirmed that the amplified partial 16S rDNA sequence represented “Candidatus Mycoplasma haemobos”. This is the first report of “Candidatus Mycoplasma haemobos” in buffalo, yellow cattle, and dairy cows in China.  相似文献   
46.
对山羊胚胎脊髓胶状质发育的形态学变化了系统研究,结果表明:(1)山羊脊髓胶状质在胚胎第17周以后逐渐较多的神经元胞体和较大的淡染的神经元细胞核,提示胚胎第17周龄是山羊脊髓胶状质神经元发育的关键时期;(2)山羊脊髓胶状质内神经纤维在胚胎第11周时就已出现,而在髓神经纤维的髓鞘则在胚胎第15周时形成,以后逐渐发育成熟;(3)山羊脊髓胶状质的胶质细胞发育较早,在胚胎第6周末胶状质的胶质细胞发育较早,在胚胎第6周末胶状质原基刚形成时,胶质细胞核已经开始分化,到胚胎第18-19周时,胶质细胞又出现一个增殖高峰。  相似文献   
47.
动物检疫员在产地检疫、屠宰检疫环节中.动物防疫监督人员在日常监督检查中,经常会发现病害动物、动物产品,相当多的检疫监督人员在对病害动物、动物产品进行无害化处理时,不出具任何文书,直接进行无害化处理.事后甚至没有记录,在病害动物、动物产品无害化处理程序上存在很多问题,如果货主提起行政诉讼,那动物防疫监督机构就面临着败诉的危险.笔者现就病害动物、动物产品无害化处理程序谈谈自己的看法。  相似文献   
48.
49.
Objective To determine the effect of 0.5% proparacaine in tonometry by evaluating corneal touch threshold (CTT) and intraocular pressure (IOP). Animal studied Nine rats (18 eyes, Sprague–Dawley) and 10 dogs (20 eyes, Beagle) Procedures The IOP and CTT were measured in each eye before and after topical anesthesia with 0.5% proparacaine. The IOP was evaluated using Tonopen for dogs and Tonolab for rats. The corneal sensitivity was evaluated by CTT through a Cochet–Bonnet aesthesiometer. Results The mean IOP was not significantly changed in rats or dogs before and after topical anesthesia. However, after application of proparacaine, CTT was significantly increased in both animal groups compared with that before application of proparacaine. Conclusion From this study, topical anesthesia was found to significantly lower the corneal sensitivity but have little effect on IOP measurements. In ophthalmologic examination, topical anesthesia can be used to reduce corneal sensation without an effect on IOP.  相似文献   
50.
通过显微镜检查对来源于全国各地的37种出口观赏鸟进行了血液原虫调查。共检查血样1144份,结果为:血液原虫的检出率为2.1%,主要是血变原虫和/或疟原虫。感染季节以秋冬两季为主,易感鸟品种主要是白腰文鸟、红喉歌鸲、蓝歌鸲、暗绿绣眼鸟、豆冠、白燕、情侣鹦鹉。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号