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   228篇
  免费   11篇
  国内免费   3篇
林业   5篇
农学   5篇
基础科学   1篇
  19篇
综合类   67篇
农作物   2篇
水产渔业   2篇
畜牧兽医   104篇
园艺   5篇
植物保护   32篇
  2022年   3篇
  2021年   4篇
  2020年   3篇
  2019年   3篇
  2018年   2篇
  2017年   10篇
  2016年   6篇
  2015年   8篇
  2014年   5篇
  2013年   6篇
  2012年   11篇
  2011年   12篇
  2010年   13篇
  2009年   7篇
  2008年   12篇
  2007年   14篇
  2006年   8篇
  2005年   11篇
  2004年   5篇
  2003年   8篇
  2002年   5篇
  2001年   3篇
  2000年   8篇
  1999年   5篇
  1998年   6篇
  1997年   5篇
  1995年   2篇
  1994年   4篇
  1993年   4篇
  1992年   3篇
  1991年   2篇
  1990年   3篇
  1989年   8篇
  1988年   3篇
  1986年   2篇
  1985年   2篇
  1984年   2篇
  1981年   2篇
  1977年   2篇
  1973年   3篇
  1971年   2篇
  1970年   1篇
  1969年   2篇
  1967年   2篇
  1965年   1篇
  1959年   2篇
  1957年   1篇
  1948年   1篇
  1944年   1篇
  1936年   1篇
排序方式: 共有242条查询结果,搜索用时 31 毫秒
51.
Treatment of dogs with acute canine polyradiculoneuritis (ACP) is restricted to physical rehabilitation and supportive care. In humans with Guillain-Barré syndrome, the counterpart of ACP, randomized trials show that IV immunoglobulin (IVIg) speeds recovery. The authors of the current study hypothesized that dogs with ACP would tolerate IVIg well and recover faster than dogs managed with supportive treatment only. Sixteen client-owned dogs with ACP were treated with IVIg, and 14 client-owned dogs served as a retrospective control group. Diagnosis was confirmed using clinical features, electrodiagnostics, cerebrospinal fluid analysis, and muscle/nerve biopsies. The duration of the initial progressive phase, the time from IVIg administration until the dogs were ambulating without assistance, and the duration of the complete episode were evaluated. Adverse reactions (anaphylaxis, mild hematuria) were observed in two dogs. Dogs treated with IVIg were ambulating without assistance after a median of 27.5 days (range, 15-127 days) from onset of clinical signs. The control group was ambulatory without assistance at a median of 75.5 days (range, 5-220 days). Even though this result is not statistically significant, there is a clear trend toward faster recovery in dogs treated with IVIg.  相似文献   
52.
为了探讨Ghrelin在绵羊卵母细胞体外成熟过程中与BCL-2、BAX的相关性及Ghrelin在绵羊卵母细胞成熟过程中可能的作用机理,试验在绵羊卵母细胞成熟液中添加500 ng/mL Ghrelin,采用实时荧光定量PCR分别在0,8,16,24小时时检测卵母细胞BCL-2、BAX的表达量。结果表明:试验组添加Ghrelin后8,16小时时卵母细胞BCL-2 mRNA相对表达量显著升高(P<0.05),但成熟后16,24小时时较8小时时有下降趋势;下降到24小时时,其表达量与0小时时没有显著变化(P>0.05);8,16小时时试验组与对照组比较差异显著(P<0.05),0,24小时时差异不显著(P>0.05)。试验组添加Ghrelin后8,16,24小时卵母细胞BAX mRNA相对表达量较0小时时下降,且差异显著(P<0.05),但成熟后16,24小时时与8小时时比较有上升趋势;在8,16小时时试验组较对照组BAX mRNA相对表达量均有所下降,且差异有显著性(P<0.05),而在0,24小时时差异不显著(P>0.05)。说明Ghrelin在绵羊卵母细胞成熟过程中与BCL-2和BAX的表达存在相关性,推测Ghrelin在卵母细胞成熟过程中存在积极调控作用。  相似文献   
53.
疣枝桦是阿勒泰地区广泛分布的乡土树种,文章简要介绍了疣枝桦在阿勒泰地区的分布、生物学特性以及播种繁殖过程,其中包括采种、种子处理、播种前的整地、播种、苗期管理等。文章阐述了疣枝桦育苗技术措施,在生产实践中具有较强的可操作性。  相似文献   
54.
The purpose of this study was to determine the frequency of different tumor types within a large cohort of cats with intracranial neoplasia and to attempt to correlate signalment, tumor size and location, and survival time for each tumor. Medical records of 160 cats with confirmed intracranial neoplasia evaluated between 1985 and 2001 were reviewed. Parameters evaluated included age, sex, breed, FeLV/FIV status, clinical signs, duration of signs, number of tumors, tumor location(s), imaging results, treatment, survival times, and histopathologic diagnosis. Most of the cats were older (11.3 +/- 3.8 years). Primary tumors accounted for 70.6% of cases. Metastasis and direct extension of secondary tumors accounted for only 5.6 and 3.8% of cases, respectively. Twelve cats (7.5%) had 2 or more discrete tumors of the same type, whereas 16 cats (10.0%) had 2 different types of intracranial tumors. The most common tumor types were meningioma (n = 93, 58.1%), lymphoma (n = 23, 14.4%), pituitary tumors (n = 14, 8.8%), and gliomas (n = 12, 7.5%). The most common neurological signs were altered consciousness (n = 42, 26.2%), circling (n = 36, 22.5%), and seizures (n = 36, 22.5%). Cats without specific neurological signs were common (n = 34, 21.2%). The tumor was considered an incidental finding in 30 (18.8%) cats. In addition to expected relationships (eg, meninges and meningioma, pituitary and pituitary tumors), we found that lesion location was predictive of tumor type with diffuse cerebral or brainstem involvement predictive of lymphoma and third ventricle involvement predictive of meningioma.  相似文献   
55.
One of the most serious diseases of banana is fusarium wilt, caused by Fusarium oxysporum f.sp. cubense ( Foc ). The objectives of this study were to isolate and identify nonpathogenic F. oxysporum strains from soils suppressive to banana wilt, and to determine the diversity of these isolates. More than 100 Fusarium strains were isolated from the rhizosphere of banana plants and identified to species level. Pathogenicity testing was carried out to confirm that these isolates were nonpathogens of banana. A PCR-based RFLP analysis of the intergenic spacer region of the ribosomal RNA operon was used to characterize the nonpathogens. The isolates were also compared with isolates of Foc from South Africa and the known biological control isolate of F. oxysporum , Fo47. The species-specific primers FOF1 and FOR1, in addition to morphological features, were used to confirm the identity of F. oxysporum isolates included in the PCR-RFLP analysis. Twelve different genotypes could be distinguished, identified by a six-letter code allocated to each isolate following digestion with the restriction enzymes Hae III, Hha I, Hin fI, Msp I, Rsa I and Scrf I. Eleven of these included nonpathogenic F. oxysporum isolates, and these groups could all be distinguished from the genotype that included Foc . Fo47 was included in one of the genotype groups consisting of nonpathogenic F. oxysporum isolates from South Africa.  相似文献   
56.
SONOGRAPHIC RENAL FINDINGS IN 20 DOGS WITH LEPTOSPIROSIS   总被引:1,自引:0,他引:1  
Abdominal ultrasound examinations of 20 dogs with confirmed leptospirosis were reviewed retrospectively for renal abnormalities. Three dogs had a normal ultrasound examination. The remaining 17 dogs had sonographic abnormalities of the kidneys. These abnormalities, seen either alone or in combination, included renalmegaly (n=10), pyelectasia (n=9), increased cortical echogenicity (n=15), perinephric effusion (n=5), and a medullary band of increased echogenicity (n=6). At our institution, the medullary band of increased echogencity has only been seen in dogs with leptospirosis and may therefore be a specific sonographic sign for this disease.  相似文献   
57.
ABSTRACT The effect of the plant on the diversity of soilborne populations of Fusarium oxysporum was assessed after successive cultures of flax, melon, tomato, and wheat in separate samples of the same soil. Forty soil-borne isolates of F. oxysporum and forty root-colonizing isolates of each plant species were sampled during the first (T0) and fourth (T1) cultures. The population structures were assessed by a genotypic method based on restriction fragment analysis of polymerase chain reaction-amplified ri-bosomal intergenic spacer (IGS) DNA. Sixteen IGS types were defined among the four hundred isolates analyzed. The distributions of soil isolates among IGS types were similar at both sampling times. The structure of F. oxysporum populations associated with the roots of flax or melon did not differ from the structure of soilborne populations. In contrast, the structure of F. oxysporum populations associated with roots of wheat or tomato differed from the structure of soilborne populations. High frequencies were found for IGS type 4 among wheat isolates at both T0 and T1 and for IGS type 11 among tomato isolates at T1. Moreover, a high level of genetic divergence was obtained between IGS types 4 and 11. Our results suggest that tomato and wheat have a selective effect on soilborne populations of F. oxysporum and that this effect seems to be plant specific.  相似文献   
58.
Disseminated pulmonary and subcutaneous-muscular hemangiosarcoma at the left hemimandible was diagnosed postmortem in a 2-year-old Jersey bull that presented with a 7-day history of facial swelling from suspected traumatic injury. Hemangiosarcoma is uncommon in cattle and has never been reported to affect the bones of the skull.  相似文献   
59.
An 8-year-old female spayed domestic shorthair cat was presented for several months of weight loss, decreased appetite, and 2 bilateral, ventral cervical masses. Initial cytologic samples were interpreted as reactive lymphoid hyperplasia. Evaluation of subsequent mass aspirates revealed small numbers of large binucleated and multinucleated cells resembling Reed-Sternberg cells admixed with more numerous small and intermediate-sized lymphocytes. In histopathologic sections, the normal architecture of the lymph node was largely effaced by a slightly heterogeneous mass composed of round cells arranged in densely cellular sheets with a minor population of large (25-mum diameter) mononuclear cells and a few very large (30-40-mum diameter) binucleated or multinucleated cells interpreted as Reed-Sternberg-like cells. Immunohistochemically, the large neoplastic (Reed-Sternberg-like) cells were negative for CD18, CD3, CD20, and CD79a while the background population consisted of about 70% T cells and 30% B cells. This pattern of immunohistochemical staining along with cytologic and histopathologic findings supported a diagnosis of Hodgkin's-like lymphoma, specifically, the lymphocyte-rich subtype. Hodgkin's-like lymphoma has been reported previously in cats and should be suspected when Reed-Sternberg-like cells are observed in cytologic preparations of lymph node aspirates. Histopathology and immunohistochemistry are necessary for a definitive diagnosis.  相似文献   
60.
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