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   214篇
  免费   10篇
林业   20篇
农学   14篇
  12篇
综合类   8篇
农作物   6篇
水产渔业   20篇
畜牧兽医   132篇
园艺   7篇
植物保护   5篇
  2022年   1篇
  2021年   1篇
  2020年   2篇
  2019年   1篇
  2018年   2篇
  2017年   5篇
  2016年   7篇
  2015年   1篇
  2014年   4篇
  2013年   5篇
  2012年   5篇
  2011年   14篇
  2010年   3篇
  2009年   8篇
  2008年   10篇
  2007年   17篇
  2006年   4篇
  2005年   15篇
  2004年   15篇
  2003年   15篇
  2002年   10篇
  2001年   12篇
  2000年   10篇
  1999年   7篇
  1998年   6篇
  1997年   3篇
  1996年   3篇
  1995年   1篇
  1992年   8篇
  1991年   4篇
  1990年   6篇
  1989年   5篇
  1988年   1篇
  1985年   1篇
  1984年   1篇
  1982年   2篇
  1981年   1篇
  1978年   1篇
  1977年   1篇
  1975年   1篇
  1974年   1篇
  1973年   1篇
  1969年   1篇
  1968年   1篇
  1964年   1篇
排序方式: 共有224条查询结果,搜索用时 15 毫秒
51.
We measured the concentrations of S-100B, a marker protein used in humans to detect brain damage, in the cerebrospinal fluid (CSF) of clinically normal cattle (n=15, mean age +/- SD: 31.8 +/- 37.5 months) and of cattle with various inflammatory disorders (n=43, 70.6 +/- 31.9 months). The mean +/- SD CSF S-100B level was 2.9 +/- 1.6 ng/ml in the normal group and 7.0 +/- 7.4 ng/ml in the diseased group. Thirteen diseased cattle that had developed no obvious neurological signs showed abnormally high S-100B concentrations (> 8.0 ng/ml), whereas the two cattle with neurological disorders did not. No particular disease could be related to the S-100B rise. Therefore, it remains inconclusive whether measurement of CSF S-100B concentration is useful in veterinary neurological diagnosis.  相似文献   
52.
Intracerebral microdialysis combined with electroencephalographic recordings was performed on 4 dogs of a familial idiopathic epileptic Shetland sheepdog colony to identify the kinds of neurotransmitters responsible for seizure activity. Immunohistochemistry using glutamate (Glu), glutamate transporter (GLT-1 and GLAST), and glutamine synthetase (GS) antibodies was also carried out on the cerebrum of four familial dogs that died of status epilepticus (SE). High values for extracellular levels of Glu and aspartate (ASP) were detected in association with an increased number of spikes and sharp waves during hyperventilation in 3 of 4 the familial epileptic dogs. The values of other amino acids analyzed were not altered in any of the familial epileptic dogs. Immunohistochemically, Glu-positive granules were occasionally found in the perineuronal spaces of the cerebral cortex in 3 of the familial epileptic dogs that died of SE. Immunostains for GLT-1 antibody predominantly decreased in the cerebral cortex and lateral nucleus of the thalamus in all the dogs that died of SE, whereas there were no differences detected in immunolabellings for GLAST and GS antibodies between familial epileptic dogs and controls. These results suggest that an extracellular release of both Glu and Asp may play an important role in the occurrence of seizure activity in this epileptic colony, and that a decreased expression of astrocytic GLT-1 may be related to development of SE.  相似文献   
53.
Genetically modified corn has been approved as an animal feed in several countries, but information about the fate of genetically modified DNA and protein in vivo is insufficient. Genetically modified corn Bt11 is developed by inserting a recombinant DNA sequence encoding insecticidal Cry1Ab protein from Bacillus thuringiensis subsp. kurstaki. We examined the presence of corn intrinsic and recombinant cry1Ab gene by PCR, and the Cry1Ab protein by immunological tests in the gastrointestinal contents of five genetically modified corn Bt11-fed and five nongenetically modified corn-fed pigs. Fragments of corn zein (242 bp), invertase (226 bp) and of ribulose-1,5-bisphosphate carboxylase/ oxygenase genes (1,028 bp) were detected in the gastrointestinal contents of both Bt11 and nongenetically modified corn-fed pigs. Fragments of recombinant cry1Ab gene (110 bp and 437 bp) were detected in the gastrointestinal contents of the Bt11-fed pigs but not in the control pigs. Neither corn intrinsic nor cry1Ab gene fragments were detected in the peripheral blood by PCR. The gastrointestinal contents were positive for Cry1Ab protein by ELISA, immunochromatography, and immunoblot; however, these methods did not work for blood and precluded conclusions about any potential absorption of the protein. These results suggest that ingested corn DNA and Cry1Ab protein were not totally degraded in the gastrointestinal tract, as shown by their presence in a form detectable by PCR or immunological tests.  相似文献   
54.
OBJECTIVE: To map central benzodiazepine receptors (BZRs) in the brain of cats by use of positron-emission tomography (PET) and [11C]flumazenil. ANIMALS: 6 male cats that weighed between 2.0 and 3.6 kg. PROCEDURE: Brain images obtained by PET evaluation of [11C]flumazenil were superimposed on T2-weighted magnetic-resonance imaging (MRI) scans of the same cats. Detailed anatomic regions, such as the cerebral cortex, striatum, thalamus, midbrain, and cerebellum, on the PET images were evident by PET-MRI registration. Regional binding of [11C]flumazenil to BZRs was quantitatively measured by use of a model with 2 tissue compartments and 4 variables. RESULTS: The highest value for distribution volume was observed in the cerebral cortex, and the lowest value was found in the midbrain of cats. CONCLUSIONS AND CLINICAL RELEVANCE: Binding of [11C]flumazenil to BZRs in the brain of cats can be quantitatively measured by use of PET with the aid of PET-MRI registration. It is difficult to diagnose changes in these neuroreceptors within the field of current veterinary science. In the future, PET should prove useful for investigating and diagnosing brain disorders in animals in clinical settings.  相似文献   
55.
A 7-year-old female Labrador Retriever dog showed extreme muscular weakness, muscle wasting, dysbasia, and mild dysphagia. An elevated value of creatine kinase (335 IU/liter) in the serum was detected. Electromyographic findings included increased insertional activity, fibrillation potentials, and bizarre high-frequency repetitive potentials. Histopathologic examination of skeletal muscles revealed myofiber necrosis and phagocytosis, regeneration of myofibers, and perivascular, perimysial, and endomysial infiltrations of lymphocytes, macrophages and plasma cells. Immunohistochemical evaluation demonstrated that infiltrative cells in the early stage of myositis were CD8+ T-cells and that an increased expression of major histocompatibility complex (MHC) class I was apparent on the surface of nonnecrotic muscle fibers. In contrast, many CD3+ cells (T cells) and HLA-DR-positive macrophages and B lymphocytes were found in the severely affected areas. These results suggest that both expression of MHC class I and CD8+ T-cell infiltration may play an important role in initiation of myositis. These histopathologic findings resemble those reported in naturally occurring polymyositis in humans.  相似文献   
56.
Sequences of the internal transcribed spacer (ITS) region 1 were used to examine the phylogenetic relationships among races of 19 isolates of Phytophthora vignae f. sp. adzukicola and between this forma specialis and three isolates of the closely related P. vignae f. sp. vignae. The ITS 1 sequences were highly conserved (> 98.7% similarity) among representatives of both formae speciales groups. The results of this study indicate that P. vignae is a monophyletic group. The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank databases under the accession nos. AB120062–AB120080 and AB120122  相似文献   
57.
A 10-year-old Golden Retriever dog had a solitary tumor mass arising from the greater omentum. Histologically, the tumor showed varying cellularity and patterns of cellular arrangement. In dense cellular areas, spindle-shaped cells were arranged in interlacing bundles. The sparse cellular area was characterized by loosely arranged fusiform cells. The neoplastic cells frequently contained PAS-positive eosinophilic globules in the cytoplasm, and mitotic figures were frequently observed. The tumor cells were positive to vimentin, S-100 protein, glial fibrillary acidic protein, myelin basic protein, neuron-specific enolase and myoglobin. The present tumor was diagnosed as a malignant peripheral nerve sheath tumor (MPNST) with eosinophilic cytoplasmic globules arising from the greater omentum. To our knowledge, this may be the first case of primary omental MPNST in domestic animals.  相似文献   
58.
The correlation between skin barrier function and transepidermal water loss (TEWL) was evaluated in dogs. Stratum corneum (SC) of 10 healthy dogs was removed by tape stripping (TS), which decreased the corneal layer to allow for permeation of fluorescent dye into skin. TEWL of damaged skin was measured with the closed-chamber-type TEWL analyzer, CC-01. The frequency of TS was directly related to the decrease of SC and the increased permeation of fluorescent dye, and TEWL increased with increasing impairment of skin barrier function. The results suggest that increased TEWL reflects impaired canine skin barrier function.  相似文献   
59.
60.
The development of a layout plan for a new plant with the aid of genetic algorithms was studied to place the machines so that the plant floor was effectively utilized and the operation would not be impeded. Genetic algorithms are search algorithms based on the mechanics of natural evolution and natural genetics to solve problems in engineering fields. Simulation with the aid of genetic algorithms was undertaken step by step. The first seven hundred strings (chromosomes) were generated at random to organize an initial population. Each string consisted of 40 bits (genes), which represented characteristics of machines (x- andy-coordinates and inlet and outlet formations of materials on machines) in the binary coding. Then the simulation was undertaken by repeating selection, crossover, reproduction, and mutation of strings until all strings were saturated with the highest evaluation (fitness of chromosomes to environments in the case of creatures). Under some limitations, an acceptable layout plan of the modeled plant involving four wood-processing machines was obtained according to evaluation indices.Part III of this series appeared inMokuzai Gakkaishi 37: 702–710, 1991.Part of this report was presented at the 47th annual meeting of the Japan Wood Research Society, Kocht, April 1997  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