全文获取类型
收费全文 | 5765篇 |
免费 | 409篇 |
国内免费 | 3篇 |
专业分类
林业 | 149篇 |
农学 | 123篇 |
基础科学 | 50篇 |
642篇 | |
综合类 | 1465篇 |
农作物 | 192篇 |
水产渔业 | 224篇 |
畜牧兽医 | 3081篇 |
园艺 | 63篇 |
植物保护 | 188篇 |
出版年
2020年 | 48篇 |
2019年 | 50篇 |
2018年 | 71篇 |
2017年 | 66篇 |
2016年 | 77篇 |
2015年 | 55篇 |
2014年 | 87篇 |
2013年 | 231篇 |
2012年 | 165篇 |
2011年 | 185篇 |
2010年 | 104篇 |
2009年 | 104篇 |
2008年 | 202篇 |
2007年 | 197篇 |
2006年 | 203篇 |
2005年 | 180篇 |
2004年 | 177篇 |
2003年 | 187篇 |
2002年 | 159篇 |
2001年 | 140篇 |
2000年 | 167篇 |
1999年 | 144篇 |
1998年 | 55篇 |
1997年 | 54篇 |
1995年 | 50篇 |
1992年 | 124篇 |
1991年 | 123篇 |
1990年 | 121篇 |
1989年 | 117篇 |
1988年 | 97篇 |
1987年 | 94篇 |
1986年 | 135篇 |
1985年 | 152篇 |
1984年 | 119篇 |
1983年 | 113篇 |
1982年 | 70篇 |
1981年 | 83篇 |
1980年 | 65篇 |
1979年 | 110篇 |
1978年 | 98篇 |
1977年 | 59篇 |
1976年 | 50篇 |
1975年 | 54篇 |
1974年 | 57篇 |
1973年 | 77篇 |
1972年 | 77篇 |
1971年 | 67篇 |
1970年 | 56篇 |
1969年 | 62篇 |
1968年 | 62篇 |
排序方式: 共有6177条查询结果,搜索用时 15 毫秒
101.
102.
Sakamoto K Lewbart GA Smith TM 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2001,30(2):50-52
Abstract: Blood samples were collected from 29 juvenile red pacu ( Piaractus brachypomus ), ornamental freshwater fish, to establish baseline blood chemistry values. Mean (minimum-maximum) values, obtained by automated bichromatic analysis and ion selective electrode analysis, were as follows: sodium, 150.4 (146–159) mmol/L; potassium, 3.93 (2.7–5.0) mmol/L; chloride, 138.7 (128–150) mmol/L; total CO2 , 7.5 (6–10) mmol/L; albumin, 0.86 (0.5–1.0) g/dL; lactate dehydrogenase, 237.8 (65–692) IU/L; aspartate aminotransferase, 49.1 (0–125) IU/L; creatinine, 0.31 (0.2–0.4) mg/dL; calcium, 10.80 (9.5–12.5) mg/dL; anion gap, 6.89 (1.2–12.5) mmol/L; and phosphorus, 7.29 (4.1–8.9) mg/dL. 相似文献
103.
A new syndrome of anemia, alopecia, and dyskeratosis was identified in Polled Hereford calves in this study. Cutaneous changes included hyperkeratosis and hair loss around the muzzle and ear margins, which progressed to a generalized alopecia and hyperkeratotic dermatitis. Histologically, orthokeratotic hyperkeratosis with dyskeratosis of epidermal and follicular keratinocytes was present. Alopecia was correlated with dyskeratosis of Huxley's layer and an increasing proportion of follicles in the telogen phase of the hair cycle. Dermatitis was characterized by a mild dermal mononuclear cell infiltrate and mild lymphocytic perivascular dermatitis. The anemia present at birth was nonprogressive and was classified as normochromic and normocytic to macrocytic. Reticulocytosis was absent, but bone marrow was markedly hyperplastic. Nuclear cytoplasmic asynchrony of the rubricyte and metarubricyte stages occurred in the bone marrow. Abnormal rubricyte nuclei and maturation arrest at the late rubricyte stage were common. Cytologic features of the erythroid series are similar to those of type I congenital dyserythropoietic anemia of human beings. Genealogic features suggest that this is a primary hereditary defect. The mode of inheritance, however, remains to be determined. 相似文献
104.
105.
OBJECTIVE: To document the clinical signs and management of primary glaucoma in Burmese cats. DESIGN: A retrospective study of six affected Burmese cats, from 1996 to 2001. Procedure Six Burmese cats diagnosed with primary glaucoma were managed over periods varying from 3 months to 4.5 years. Clinical details were obtained from practice records. Gonioscopic examination of the drainage or iridocorneal angle in eyes of these affected cats was made. RESULTS: Six desexed female Burmese cats (ages 7.0 to 10.5 years) presented with complaints of either unilateral (n = 4) or bilateral (n = 2) red eye, dilated pupil or enlarged eye. In one of the affected cats, one eye had been enucleated prior to the commencement of the study, thus a total of 11 eyes were examined. Clinically, all affected eyes (n = 8) had injected episcleral blood vessels and elevated intraocular pressure. Gonioscopy revealed the presence of nine narrow and two closed iridocorneal angles. Medical therapy included topical 2% dorzolamide (n = 8), 0.5% timolol maleate (n = 1), 0.005% latanoprost (n = 1) and 0.5-1.0% prednisolone acetate (n = 8). Surgery was performed in six eyes using either diode laser (n = 5) and/or cryothermy (n = 2) and one eye was eviscerated, with implantation of a prosthesis. With therapy, five affected eyes maintained vision and normal intraocular pressure, one eye remained blind with normal intraocular pressure, one eye remained blind with elevated intraocular pressure and one eye was eviscerated. CONCLUSIONS: The Burmese cat may be predisposed to primary narrow-angle glaucoma. Early diagnosis and continuous antiglaucoma therapy can help control intraocular pressure and maintain vision. 相似文献
106.
Vaccination of rats and pigs against Trichinella spiralis spiralis using the subspecies, T. spiralis nativa. 下载免费PDF全文
H J Smith 《Canadian journal of veterinary research》1987,51(3):370-372
Rats and pigs were vaccinated against Trichinella spiralis spiralis either by feeding infective larvae of the subspecies, Trichinella spiralis nativa in musculature or by gavage. The number of larvae established in the musculature of vaccinated nonchallenged and vaccinated challenged rats and pigs were negligible and statistically comparable, while highly significant infections were established in the nonvaccinated challenged rats and pigs. High vaccination doses of T. spiralis nativa gave virtually complete protection to challenge with T. spiralis spiralis in pigs. The results of one trial in rats with a lower vaccination dose of larvae suggest that there is a minimal vaccination dose of larvae required to elicit marked resistance to challenge. The low numbers of muscle larvae established due to the high vaccination doses of larvae confirm the low infectivity of the subspecies, T. spiralis nativa in rats and pigs. 相似文献
107.
S L Peterson M M Smith C W Senders 《Journal of the American Veterinary Medical Association》1987,191(12):1582-1584
After laryngeal surgery, cranial glottic stenosis secondary to laryngeal web formation was diagnosed as the cause of upper airway obstruction in 4 dogs. Initial treatment of 3 dogs by peroral laryngeal web excision resulted in rapid recurrence of clinical signs. Subsequently, these 3 and the fourth dog were treated by scar excision, mucosal flap coverage, and placement of a silicone intraluminal laryngeal stent for 14 days. By 5 months (average) after surgery, on the basis of clinical evaluation of exercise intolerance, respiratory distress, and stridor, all dogs had alleviation of upper airway obstruction. 相似文献
108.
109.
Several pharmaceutical compounds were evaluated for their ability to selectively inhibit activated coagulation factor-XIII-like enzyme activity (eg, XIIIa*) in pooled equine plasma. Presence of coagulation factor-XIIIa*-like enzyme activity in plasma was established by assay procedures involving incorporation of the fluorescent amine compound, monodansylcadaverine, into purified casein, which served as a protein substrate. Pharmaceuticals inhibitory to coagulation factor-XIIIa*-like enzyme activity were recognized by plasma gel formation of high spectrophotometric transmittance (transparency), solubility of transparent fibrin gels in concentrated urea solution, in conjunction with simultaneous depletion of native fibrinogen fractions, and production of fibrin monomer. Compounds acting primarily as anticoagulants were recognized by lack of plasma gel formation, but retaining high spectrophotometric transmittance and no detectable depletion of native fibrinogen fractions. Compounds failing to inhibit either thrombin-mediated fibrinogen-fibrin transformation (ie, coagulation) or coagulation factor-XIIIa*-like enzyme activity were recognized by opaque plasma gels caused by fibrin polymerization, low spectrophotometric transmittance values, and coinciding with depletion of native fibrinogen fractions. Pharmaceuticals capable of exerting selective inhibition of coagulation factor-XIIIa*-like enzyme activity were further classified as competitive inhibitors of phase 1 (carbamide) or phase 2 (terminal amine) of the transglutamination process. 相似文献
110.
A selected group of pharmaceutical compounds were evaluated for the ability to inhibit the biochemical activity of fibrinoligase (coagulation factor XIIIa*) in pooled equine plasma. Criteria for the pharmaceuticals selected were based on the mechanism of the transglutamination biochemical reaction mediated by coagulation factor XIIa*. These criteria were complemented by recognition of the molecular configuration and chemical composition of amino acid residue side chains involved in the process of covalent fibrin monomer polymerization (cross-linking, transglutamination) mediated by this enzyme. Each pharmaceutical was evaluated individually and in combination with other potential coagulation factor XIIIa* inhibitors in an effort to detect additive and synergistic phenomenon. In this context, pharmaceuticals with a carbonylamide (eg, cefuroxime, Girard's reagent-P, prolinamide) were applied in concert with compounds with a terminal amine (eg, D-arginine, L-lysine) functional group. In concept, this method theoretically served to competitively simulate glutamine and lysine amino acid residues within strands of fibrin monomer substrate involved in phase I (carbonylamide) and phase II (terminal amine) of the transglutamination reaction (covalent fibrin monomer cross-linking). Halogen-dinitro and ethylene compounds were also evaluated because of their reported ability to inactivate enzyme systems dependent on an intact sulfhydryl group located at their biochemically active site (eg, cystine amino acid residue). This group of pharmaceutical compounds failed to inhibit the biochemical activity mediated by coagulation factor XIIIa* in equine plasma. 相似文献