全文获取类型
收费全文 | 1283篇 |
免费 | 68篇 |
国内免费 | 2篇 |
专业分类
林业 | 61篇 |
农学 | 15篇 |
基础科学 | 2篇 |
111篇 | |
综合类 | 187篇 |
农作物 | 29篇 |
水产渔业 | 135篇 |
畜牧兽医 | 751篇 |
园艺 | 19篇 |
植物保护 | 43篇 |
出版年
2021年 | 12篇 |
2020年 | 10篇 |
2019年 | 19篇 |
2018年 | 17篇 |
2017年 | 15篇 |
2016年 | 17篇 |
2015年 | 15篇 |
2014年 | 15篇 |
2013年 | 53篇 |
2012年 | 37篇 |
2011年 | 50篇 |
2010年 | 27篇 |
2009年 | 31篇 |
2008年 | 50篇 |
2007年 | 45篇 |
2006年 | 49篇 |
2005年 | 31篇 |
2004年 | 37篇 |
2003年 | 31篇 |
2002年 | 59篇 |
2001年 | 32篇 |
2000年 | 42篇 |
1999年 | 42篇 |
1998年 | 29篇 |
1997年 | 31篇 |
1996年 | 23篇 |
1995年 | 14篇 |
1994年 | 9篇 |
1993年 | 13篇 |
1992年 | 26篇 |
1991年 | 31篇 |
1990年 | 44篇 |
1989年 | 23篇 |
1988年 | 30篇 |
1987年 | 17篇 |
1986年 | 18篇 |
1985年 | 20篇 |
1984年 | 15篇 |
1983年 | 17篇 |
1982年 | 11篇 |
1981年 | 12篇 |
1980年 | 12篇 |
1979年 | 20篇 |
1978年 | 14篇 |
1977年 | 11篇 |
1975年 | 16篇 |
1973年 | 15篇 |
1972年 | 15篇 |
1971年 | 10篇 |
1970年 | 16篇 |
排序方式: 共有1353条查询结果,搜索用时 15 毫秒
11.
Gonçalves R Platt SR Llabrés-Díaz FJ Rogers KH de Stefani A Matiasek LA Adams VJ 《Journal of Feline Medicine and Surgery》2009,11(2):53-59
Medical records of 92 cats presented with clinical signs of spinal cord disease, which had undergone magnetic resonance imaging (MRI), were reviewed. The cats were grouped into seven categories based upon the diagnosis suggested by results of MRI, cerebrospinal fluid analysis and other diagnostic procedures: neoplastic (n=25), inflammatory or infectious (n=13), traumatic (n=8), vascular (n=6), degenerative (n=5), anomalous (n=3) and those with an unremarkable MRI (n=32). There were two independent predictors of abnormal MRI findings: severity of clinical signs and presence of spinal pain. Abnormal MRI findings and speed of onset of disease were significantly associated with survival. For the 32 cats with unremarkable MRI findings, only nine died due to spinal disease and, therefore, the median survival time (MST) was not reached (lower 95% confidence interval (CI)=970 days). For the 60 cats with abnormal MRI findings, 37 died due to their disease and the MST was 138 days (95% CI: 7-807). 相似文献
12.
Ultrasonographic findings in dogs and cats with oxalate nephrosis attributed to ethylene glycol intoxication: 15 cases (1984-1988) 总被引:1,自引:0,他引:1
W H Adams R L Toal M A Breider 《Journal of the American Veterinary Medical Association》1991,199(4):492-496
Renal ultrasonographic findings in 12 dogs and 3 cats determined to have oxalate nephrosis presumed to be secondary to ethylene glycol intoxication were examined. Ultrasonographic changes varied from mild to marked increases in renal cortical echogenicity. A pattern of greater than normal cortical and medullary echogenicity with persistence of areas of lesser echo intensity at the corticomedullary junction and central medullary regions was observed. This pattern, termed the halo sign, was recognized in 7 dogs and 1 cat concurrent with the development of clinical anuria. Ultrasonographic patterns in these clinical cases were similar to those observed in a previous study of dogs with experimentally induced ethylene glycol nephrosis. Ultrasonographic findings were not considered pathognomonic of ethylene glycol nephrosis. Due to the high death rate reported in the cases surveyed, detection of ultrasonographic changes was considered to warrant a guarded to poor prognosis. Because of the association of the halo sign with anuria, its detection was considered to warrant a grave prognosis. 相似文献
13.
Nine cats, from 11 to 17 years of age (mean 13.6 years of age), were diagnosed with a cranial mediastinal cyst. Thoracic radiographs in all cats were characterized by an increased soft tissue opacity in the cranial mediastinum confirmed to be a cyst by ultrasonography or necropsy. Ultrasonographically cysts appeared as an anechoic mass. A low-cellularity clear fluid was obtained on aspiration. The majority of the cats (n = 8) presented for unrelated conditions with no signs of respiratory distress. No treatment for the cyst was pursued except for drainage during ultrasonographic-guided aspiration in several cats. On follow-up of eight cats, none were symptomatic for the cyst from 3-45 months after diagnosis. Mediastinal cyst should be considered when a cranial mediastinal mass is evident radiographically in an older cat. The majority of feline cranial mediastinal cysts are benign with no need for treatment. 相似文献
14.
Bonnie K. Lefbom DVM William H. Adams DVM Diann L. Weddle DVM 《Veterinary radiology & ultrasound》1996,37(6):420-423
In radiographs of a domestic short haired cat of unknown age, mineralization was identified in the pulmonary parenchyma, peripheral pulmonary vessels, the aortic outflow tract, aortic valve, celiac artery, cranial mesenteric artery, and the internal and external iliac arteries. The diffuse arterial mineralization was characterized histopathologically as arteriosclerosis. This is the first report of mineralized arteriosclerosis in a cat with corresponding radiographic signs. The arteriosclerosis is thought to be due to systemic hypertension but a definitive cause for the profound mineralization was not found. Causes of soft tissue mineralization are reviewed. 相似文献
15.
16.
Subcellular calcium transients visualized by confocal microscopy in a voltage-clamped vertebrate neuron 总被引:25,自引:0,他引:25
Confocal laser-scanned microscopy and long-wavelength calcium (Ca2+) indicators were combined to monitor both sustained and rapidly dissipating Ca2+ gradients in voltage-clamped sympathetic neurons isolated from the bullfrog. After a brief activation of voltage-dependent Ca2+ channels, Ca2+ spreads inwardly, and reaches the center of these spherical cells in about 300 milliseconds. Although the Ca2+ redistribution in the bulk of the cytosol could be accounted for with a radial diffusion model, local nonlinearities, suggesting either nonuniform Ca2+ entry or spatial buffering, could be seen. After electrical stimulation, Ca2+ signals in the nucleus were consistently larger and decayed more slowly than those in the cytosol. A similar behavior was observed when release of intracellular Ca2+ was induced by caffeine, suggesting that in both cases large responses originate from Ca2+ release sites near or within the nucleus. These results are consistent with an amplification mechanism involving Ca2(+)-induced Ca2+ release, which could be relevant to activity-dependent, Ca2(+)-regulated nuclear events. 相似文献
17.
R Smith J C Kapatsa S J Sherwood T A Ficht J W Templeton L G Adams 《American journal of veterinary research》1990,51(4):518-523
The reactivity of bovine lymphocytes to 4 species of Brucella was tested in thymidine-uptake assays, using long-term cultured lymphocytes and freshly obtained blood mononuclear cells. Lymphocytes were taken from cows that had been challenge exposed with a virulent strain of B abortus at midgestation. The cows were classified retrospectively as being naturally resistant or susceptible to brucellosis. Lymphocytes taken from these cows had 3 patterns of reactivity with species of Brucella: pattern 1 was defined by reactivity with 4 species (B abortus, B canis, B suis, and B melitensis); pattern 2 was defined by reactivity with all these species, except B melitensis; pattern 3 was defined by reactivity with B abortus and B canis, but not with B suis or B melitensis. There was a statistically significant correlation between susceptibility to brucellosis and expression of lymphocyte cross-reactivity with B suis (P less than 0.01) and with B melitensis (P less than 0.001). 相似文献
18.
Carolina Fernandez-Senac Sophie Fridman Jadwiga Sokolowska Sean J. Monaghan Teresa Garzon Monica Betancor Giuseppe Paladini Alexandra Adams James E. Bron 《Journal of fish diseases》2020,43(11):1463-1472
Routine gill swabbing is a non-destructive sampling method used for the downstream qPCR detection and quantitation of the pathogen Neoparamoeba perurans, a causative agent of amoebic gill disease (AGD). Three commercially available swabs were compared aiming their application for timelier AGD diagnosis (Calgiswab® (calcium alginate fibre-tipped), Isohelix® DNA buccal and cotton wool-tipped). Calcium alginate is soluble in most sodium salts, which potentially allows the total recovery of biological material, hence a better extraction of target organisms’ DNA. Thus, this study consisted of (a) an in vitro assessment involving spiking of the swabs with known amounts of amoebae and additional assessment of retrieval efficiency of amoebae from agar plates; (b) in vivo testing by swabbing of gill arches (second, third and fourth) of AGD-infected fish. Both in vitro and in vivo experiments identified an enhanced amoeba retrieval with Calgiswab® and Isohelix® swabs in comparison with cotton swabs. Additionally, the third and fourth gill arches presented significantly higher amoebic loads compared to the second gill arch. Results suggest that limiting routine gill swabbing to one or two arches, instead of all, could likely lead to reduced stress-related effects incurred by handling and sampling and a timelier diagnosis of AGD. 相似文献
19.
J. M. Kelly G. E. Taylor Jr. N. T. Edwards M. B. Adams G. S. Edwards A. L. Friend 《Water, air, and soil pollution》1993,69(3-4):363-391
Previously published results from a multidisciplinary research program, Response of Plants to Interacting Stress (ROPIS), initiated by the Electric Power Research Insitute are summarized here. The overall objective of the ROPIS program was to develop a general mechanistic theory of plant response to air pollutants and other stresses. Direct and indirect phytotoxic impacts of O3 combined with induced deficiencies of key nutrients as a consequence of acidic deposition are important components in many of the hypotheses used to explain reported declines in forest growth. In order to address these concerns as they relate to loblolly pine (Pinus taeda L.) growth and develop a greater level of mechanistic understanding of stress response, a study was formulated with two major objectives: (i) over a multi-yr period evaluate the role of loblolly pine genotype in governing loblolly growth response to O3; and (ii) determine the underlying physiological and edaphic basis for loblolly growth response to O3, acidic precipitation, and soil Mg status. An open-top chamber facility located at Oak Ridge, TN provided controlled O3 exposure for the genotype screening study (1986–88) and controlled O3 exposure and rainfall exclusion and addition for the O3-rainfall acidity-soil Mg interaction study (1987–89). A variety of experimental techniques, measurements, and statistical procedures were used over a 4-yr period to quantify various aspects of plant growth, physiology, and soil-plant relationships. Results from the genotype screening study indicate that although family-specific O3 effects were observed at the end of the first year, no statistically significant O3 effects on diameter, height, or total biomass were evident at the end of three growing seasons; nor were any significant O3-family interactions found. In the interaction study, rainfall acidity and soil Mg level had only minimal affects on seedling growth and physiology. Ozone exposure produced significant changes in many variables, the most important being a net retention of carbon in above-ground biomass and a subsequent reduction in carbon allocation to the root system. This change could have important longterm implications for the tree's ability to obtain water and nutrients, maintain important rhizosphere organisms, and achieve a level of vigor that protects against disease and insect attack. 相似文献
20.