全文获取类型
收费全文 | 29174篇 |
免费 | 1106篇 |
国内免费 | 2篇 |
专业分类
林业 | 4666篇 |
农学 | 1709篇 |
基础科学 | 185篇 |
5575篇 | |
综合类 | 1509篇 |
农作物 | 2663篇 |
水产渔业 | 2850篇 |
畜牧兽医 | 6693篇 |
园艺 | 1368篇 |
植物保护 | 3064篇 |
出版年
2023年 | 127篇 |
2022年 | 194篇 |
2021年 | 374篇 |
2020年 | 396篇 |
2019年 | 350篇 |
2018年 | 3174篇 |
2017年 | 3124篇 |
2016年 | 1713篇 |
2015年 | 537篇 |
2014年 | 575篇 |
2013年 | 856篇 |
2012年 | 1788篇 |
2011年 | 3007篇 |
2010年 | 2505篇 |
2009年 | 1645篇 |
2008年 | 2076篇 |
2007年 | 2264篇 |
2006年 | 662篇 |
2005年 | 729篇 |
2004年 | 669篇 |
2003年 | 678篇 |
2002年 | 502篇 |
2001年 | 323篇 |
2000年 | 320篇 |
1999年 | 240篇 |
1998年 | 85篇 |
1997年 | 64篇 |
1996年 | 56篇 |
1995年 | 69篇 |
1994年 | 46篇 |
1993年 | 48篇 |
1992年 | 91篇 |
1991年 | 73篇 |
1990年 | 68篇 |
1989年 | 68篇 |
1988年 | 70篇 |
1987年 | 49篇 |
1986年 | 48篇 |
1985年 | 49篇 |
1984年 | 49篇 |
1983年 | 40篇 |
1981年 | 23篇 |
1979年 | 39篇 |
1974年 | 26篇 |
1973年 | 24篇 |
1972年 | 24篇 |
1971年 | 26篇 |
1970年 | 29篇 |
1969年 | 29篇 |
1968年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
Ménard M Fontaine M Morin M 《The Canadian veterinary journal. La revue veterinaire canadienne》1986,27(12):504-510
Fine needle aspiration biopsy is a fast and inexpensive technique well tolerated by animals. Its efficacy for the diagnosis of malignancy and determination of cellular origin was investigated for 97 malignant tumors and five benign lesions in 83 dogs and 19 cats. Histological examination of the lesions was performed in each case. Malignancy was detected by cytology in 69% of the malignant tumors. The cellular origin of the lesion was determined in 74% of the cases. Confirmation of malignancy and determination of cellular origin permitted an early diagnosis and prognosis. Since fine needle aspiration biopsy and cytology cannot definitely rule out malignancy, a surgical biopsy and histopathology should be done when malignancy is suspected clinically and not confirmed cytologically. Specimens of good quality, adequate collaboration between the cytologist and clinicians, and sufficient knowledge of pathology and cytology are basic requirements for obtaining good results with fine needle aspiration biopsy and cytology. 相似文献
22.
Transitional Cell Carcinoma of the Urinary Bladder in a Beluga Whale (Delphinapterus leucas) 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《The Canadian veterinary journal. La revue veterinaire canadienne》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Martineau D Lagacé A Massé R Morin M Béland P 《The Canadian veterinary journal. La revue veterinaire canadienne》1985,26(10):297-302
A transitional cell carcinoma of the urinary bladder was found in a beluga whale stranded in the St. Lawrence middle estuary. Various organs of this animal were submitted to high resolution gas chromatography coupled with mass spectrometry analysis. High frequency of urinary bladder cancer in the human population of the same area and the presence of carcinogenic compounds in the marine environment of this animal are discussed.
Concurrent isolation of Edwardsiella tarda from various organs of this whale is also reported.
相似文献23.
24.
Rob W. Briddon Patricia Lunness Ian D. Bedford Leony C. L. Chamberlin Theo Mesfin Peter G. Markham 《European journal of plant pathology / European Foundation for Plant Pathology》1996,102(4):397-400
The cause of a streak disease of pearl millet (Pennisetum glaucum), originating from Nigeria, has been attributed to a geminivirus belonging to the African streak virus cluster. A full-length, infectious clone of the virus was obtained which was transmissible by the vectorCicadulina mbila (Naudé). Analysis of the complete nucleotide sequence of the coat protein gene of this virus shows it to be most closely related to sugarcane streak virus. The possible evolutionary implications of this finding are discussed. 相似文献
25.
26.
Evaluation of an in-office allergy screening test in nonatopic dogs having various intestinal parasites
下载免费PDF全文
![点击此处可从《The Canadian veterinary journal. La revue veterinaire canadienne》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Paradis M Lécuyer M 《The Canadian veterinary journal. La revue veterinaire canadienne》1993,34(5):293-295
An in-office allergy screening kit was evaluated in 10 dogs that had no clinical signs of atopy but had various intestinal parasites. All 10 dogs had a positive reaction to the dust mite Dermatophagoïdes farinae, and four dogs had positive reactions to at least one other group of allergens. The kit as presently marketed gives numerous false positive results in parasitized nonatopic dogs. 相似文献
27.
28.
Two strains of bovine Theileria from northern Nigeria were shown to be identical to Theileria mutans in the indirect immunofluorescent antibody test. One of the strains was transmitted by the tick Amblyomma variegatum; large macroschizonts, typical for T mutans, could be demonstrated in infected cattle. It is concluded from these experiments and from the literature that there is reliable evidence so far for the occurrence in Nigeria of only two bovine Tehileria species, T mutans and T velifera. 相似文献
29.
Une néphrose toxique chez des veaux traités par un médicament contenant des produits de dégradation des tétracyclines
下载免费PDF全文
![点击此处可从《The Canadian veterinary journal. La revue veterinaire canadienne》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Teuscher E Lamothe P Tellier P Lavallée JC 《The Canadian veterinary journal. La revue veterinaire canadienne》1982,23(11):327-331
A toxic nephrosis in calves treated with a drug containing tetracycline degradation products 相似文献
30.
A. Schots J. De Boer A. Schouten J. Roosien J. F. Zil Verentant H. Pomp L. Bouwman-Smits H. Overmars F. J. Gommers B. Visser W. J. Stiekema J. Bakker 《European journal of plant pathology / European Foundation for Plant Pathology》1992,98(2):183-191
Engineering resistance against various diseases and pests is hampered by the lack of suitable genes. To overcome this problem we started a research program aimed at obtaining resistance by transfecting plants with genes encoding monoclonal antibodies against pathogen specific proteins. The idea is that monoclonal antibodies will inhibit the biological activity of molecules that are essential for the pathogenesis. Potato cyst nematodes are chosen as a model and it is thought that monoclonal antibodies are able to block the function of the saliva proteins of this parasite. These proteins are, among others, responsible for the induction of multinucleate transfer cells upon which the nematode feeds. It is well documented that the ability of antibodies to bind molecules is sufficient to inactivate the function of an antigen and in view of the potential of animals to synthesize antibodies to almost any molecular structure, this strategy should be feasible for a wide range of diseases and pests.Antibodies have several desirable features with regard to protein engineering. The antibody (IgG) is a Y-shaped molecule, in which the domains forming the tips of the arms bind to antigen and those forming the stem are responsible for triggering effector functions (Fc fragments) that eliminate the antigen from the animal. Domains carrying the antigen-binding loops (Fv and Fab fragments) can be used separately from the Fc fragments without loss of affinity. The antigen-binding domains can also be endowed with new properties by fusing them to toxins or enzymes. Antibody engineering is also facilitated by the Polymerase Chain Reaction (PCR). A systematic comparison of the nucleotide sequence of more than 100 antibodies revealed that not only the 3′-ends, but also the 5′-ends of the antibody genes are relatively conserved. We were able to design a small set of primers with restriction sites for forced cloning, which allowed the amplification of genes encoding antibodies specific for the saliva proteins ofGlobodera rostochiensis. Complete heavy and light chain genes as well as single chain Fv fragments (scFv), in which the variable parts of the light (VL) and heavy chain (VH) are linked by a peptide, will be transferred to potato plants. A major challenge will be to establish a correct expression of the antibody genes with regard to three dimensional folding, assembly and intracellular location. 相似文献