全文获取类型
收费全文 | 1327篇 |
免费 | 120篇 |
专业分类
林业 | 57篇 |
农学 | 29篇 |
基础科学 | 6篇 |
193篇 | |
综合类 | 148篇 |
农作物 | 37篇 |
水产渔业 | 73篇 |
畜牧兽医 | 784篇 |
园艺 | 47篇 |
植物保护 | 73篇 |
出版年
2024年 | 6篇 |
2023年 | 28篇 |
2022年 | 40篇 |
2021年 | 69篇 |
2020年 | 55篇 |
2019年 | 64篇 |
2018年 | 55篇 |
2017年 | 57篇 |
2016年 | 38篇 |
2015年 | 44篇 |
2014年 | 60篇 |
2013年 | 67篇 |
2012年 | 121篇 |
2011年 | 144篇 |
2010年 | 65篇 |
2009年 | 58篇 |
2008年 | 92篇 |
2007年 | 73篇 |
2006年 | 80篇 |
2005年 | 52篇 |
2004年 | 49篇 |
2003年 | 47篇 |
2002年 | 26篇 |
2001年 | 7篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有1447条查询结果,搜索用时 15 毫秒
1.
Sarah L Ralston 《Veterinary Clinics of North America: Equine Practice》2002,18(2):295-304, vii
Abnormally high or low blood glucose and insulin concentrations after standardized glucose tolerance tests can reflect disorders such as pituitary dysfunction, polysaccharide storage myopathies, and other clinical disorders. Glucose and insulin responses, however, are modified by the diet to which the animal has adapted, time since it was last fed, and what it was fed. Body fat (obesity), fitness level, physiologic status, and stress also alter glucose and insulin metabolism. Therefore, it is important to consider these factors when evaluating glucose and insulin tests, especially if only one sample it taken. This article describes the factors affecting glucose and insulin metabolism in horses and how they might influence the interpretation of standardized tests of glucose tolerance. 相似文献
2.
优化蛋白质营养不再仅仅是对日粮进行大致的氨基酸平衡。蛋白质的形式对猪的健康和生长会产生长远的影响。 蛋白质摄入量是生长猪营养中的一个基本要素。要提高瘦肉生长率,就需要平衡良好的氨基酸以供蛋白质合成之用,这些氨基酸需要以一定的形式通过日粮来提供。现在能够对饲料进行精确的分析,并且有来源可靠的合成氨基酸,已经为猪的蛋白质营养提供了坚实的基础。然而,有时候这会导致过量氮的排泄,因为并非提供的所有的蛋白质都会被猪吸收。过量氮的排出,不但会造成浪费,而且还会对环境造成污染。近年来,新的证据表明,单独提供氨基酸可能… 相似文献
3.
Kim M. Plummer Sarah J. Clark Lana M. Ellis Ashwini Loganathan Taha H. Al-Samarrai Erik H.A. Rikkerink Patrick A. Sullivan Matthew D. Templeton Peter C. Farley 《European journal of plant pathology / European Foundation for Plant Pathology》2004,110(3):265-274
Peptidases have been implicated in the pathogenicity of fungi that cause disease in plants. Expression of the secreted aspartic peptidase gene (gcsap), of a Glomerella cingulata isolate pathogenic on apples, is induced during appressorium formation. To determine whether the secreted aspartic peptidase (GcSAP) is essential to pathogenicity, gcsap was disrupted using a vector containing a 637 bp fragment of genomic DNA that encodes the sequence spanning the two active site aspartic acid (Asp) residues. To ensure that the truncated gcsap gene products could not have residual peptidase activity the codons for the active site residues Asp112 and Asp297 were both mutated to histidine residues. Both PCR and Southern analysis confirmed disruption of gcsap. Neither gcsap mRNA nor GcSAP activity was detected in the disruption mutant. Pathogenicity tests on fruit from three apple cultivars showed that GcSAP was not required for pathogenicity. The disruption mutant grew on medium containing protein as the sole source of nitrogen because G. cingulata secretes a previously undetected peptidase(s). A serine peptidase that had a pH optimum between pH 7.0 and 8.0 and a K
m of 0.25 mM for the synthetic substrate succinyl-Ala–Ala–Pro–Phe-p-nitroanilide was identified. 相似文献
4.
5.
Paixão Sonália Ferreira Fritzen Juliana Torres Tomazi Crespo Sarah Elizabeth Izzo de Moraes Pereira Helder Alfieri Alice Fernandes Alfieri Amauri Alcindo 《Tropical animal health and production》2018,50(8):1947-1950
Tropical Animal Health and Production - Serological studies have characterized the presence of the bovine viral diarrhea virus (BVDV) infection in water buffalo herds worldwide. However, the... 相似文献
6.
Effects of hyperbaric oxygen therapy on uncomplicated incisional and open wound healing in dogs
下载免费PDF全文
![点击此处可从《Veterinary surgery : VS》网站下载免费的PDF全文](/ch/ext_images/free.gif)
7.
8.
Sarah C. Roode Heather R. Shive Willemijn Hoorntje Jennifer Bernard Devorah M. Stowe Roy R. Pool Carol B. Grindem 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2018,47(3):484-488
A 20‐month‐old female spayed Staffordshire Terrier (22.3 kg) presented to the Orthopedic Surgery Service at North Carolina State University Veterinary Teaching Hospital for evaluation of a 6‐week history of toe‐touching to nonweight‐bearing lameness in the right hind limb. Radiographs of the right stifle revealed a multiloculated lytic lesion of the distal femur, with a large open lytic zone centrally, numerous osseous septations peripherally, and focal areas of cortical thinning and loss. An aspirate of the right distal femoral lesion yielded mildly cloudy serosanguineous fluid. Cytologic examination of the fluid revealed a pleomorphic population of discrete cells that exhibited marked anisocytosis and anisokaryosis and a variable nuclear‐to‐cytoplasmic (N:C) ratio, which were interpreted as probable neoplastic cells, with few macrophages, and evidence of hemorrhage. Given the clinical signs of pain, lesion size, and concern for malignant neoplasia, amputation of the right hind limb was performed. Histologically, the lesion had undulating walls 1‐3 mm thick with a continuous outer layer of dense fibrous tissue and an inner layer composed of reactive cancellous bone with no cortical compacta remaining. Remnants of thin fibrous or fibro‐osseous septa projected from the bony wall into the cyst lumen. The final histologic diagnosis was a benign multiloculated solitary (unicameral) bone cyst of the distal right femur. Based on the histopathologic findings, it was speculated that the cells identified on cytology were a mixture of developing osteoclasts, osteoblasts, endothelial, and stromal cells. This is the first report describing the cytologic examination of a solitary bone cyst in veterinary medicine. 相似文献
9.
Christina A. Chambers Sarah E. Smith F.A. Smith M.D. Ramsey D.J.D. Nicholas 《Soil biology & biochemistry》1980,12(2):93-100
The symbioses between Trifolium subterraneum, mycorrhizal fungi and Rhizohium are affected by (NH4)2SO4 and by the nitrification inhibitors 2-chloro-6 (trichloromethyl) pyridine (N-Serve) and 2-trichloromethyl pyridine (2TMP). At 50 μg · g?1 soil N-Serve and 2TMP had toxic effects on plant growth, measured as leaf expansion, root length and dry weight. Lower concentrations of N-Serve also produced some toxic symptoms. The addition of (NH4)2SO4 to the soil at 2 and 6 m-equiv NH+4 per pot, resulted in reduced root length and nodulation. Shoot dry weight was reduced at 6 m-equiv NH+4 per pot. In the presence of (NH4)2SO4 the toxic effects of the nitrification inhibitors on plant growth were less.Both nitrification inhibitors reduced development of mycorrhizal entry-points and extent of root colonization (% infection). Percentage infection of the root system was also reduced by (NH4)2SO4. Development of nodules on the lateral roots was increased in the presence of N-Serve at 5 and 15 μ · g?1. This effect, however, was accompanied by a marked reduction in N2ase activity. Smaller increases in nodulation were apparent with 2TMP and were associated with variable N2ase activity. 相似文献
10.
Naugle David E. Higgins Kenneth F. Nusser Sarah M. Johnson W. Carter 《Landscape Ecology》1999,14(3):267-276
We evaluated the influence of scale on habitat use for three wetland-obligate bird species with divergent life history characteristics and possible scale-dependent criteria for nesting and foraging in South Dakota, USA. A stratified, two-stage cluster sample was used to randomly select survey wetlands within strata defined by region, wetland density, and wetland surface area. We used 18-m (0.1 ha) fixed radius circular-plots to survey birds in 412 semipermanent wetlands during the summers of 1995 and 1996. Variation in habitat use by pied-billed grebes (Podilymbus podiceps) and yellow-headed blackbirds (Xanthocephalus xanthocephalus), two sedentary species that rarely exploit resources outside the vicinity of nest wetlands, was explained solely by within-patch variation. Yellow-headed blackbirds were a cosmopolitan species that commonly nested in small wetlands, whereas pied-billed grebes were an area-sensitive species that used larger wetlands regardless of landscape pattern. Area requirements for black terns (Chlidonias niger), a vagile species that typically forages up to 4 km away from the nest wetland, fluctuated in response to landscape structure. Black tern area requirements were small (6.5 ha) in heterogeneous landscapes compared to those in homogeneous landscapes (15.4–32.6 ha). Low wetland density landscapes composed of small wetlands, where few nesting wetlands occurred and potential food sources were spread over large distances, were not widely used by black terns. Landscape-level measurements related to black tern occurrence extended past relationships between wetlands into the surrounding matrix. Black terns were more likely to occur in landscapes where grasslands had not been tilled for agricultural production. Our findings represent empirical evidence that characteristics of entire landscapes, rather than individual patches, must be quantified to assess habitat suitability for wide-ranging species that use resources over large areas. 相似文献