全文获取类型
收费全文 | 18339篇 |
免费 | 123篇 |
国内免费 | 3篇 |
专业分类
林业 | 3750篇 |
农学 | 1324篇 |
基础科学 | 155篇 |
3080篇 | |
综合类 | 1013篇 |
农作物 | 2134篇 |
水产渔业 | 1951篇 |
畜牧兽医 | 1845篇 |
园艺 | 1148篇 |
植物保护 | 2065篇 |
出版年
2023年 | 10篇 |
2022年 | 13篇 |
2021年 | 32篇 |
2020年 | 35篇 |
2019年 | 49篇 |
2018年 | 2770篇 |
2017年 | 2729篇 |
2016年 | 1226篇 |
2015年 | 107篇 |
2014年 | 61篇 |
2013年 | 90篇 |
2012年 | 917篇 |
2011年 | 2243篇 |
2010年 | 2166篇 |
2009年 | 1324篇 |
2008年 | 1450篇 |
2007年 | 1697篇 |
2006年 | 150篇 |
2005年 | 201篇 |
2004年 | 208篇 |
2003年 | 238篇 |
2002年 | 153篇 |
2001年 | 54篇 |
2000年 | 68篇 |
1999年 | 30篇 |
1998年 | 22篇 |
1997年 | 19篇 |
1996年 | 16篇 |
1995年 | 16篇 |
1994年 | 14篇 |
1993年 | 21篇 |
1992年 | 22篇 |
1991年 | 15篇 |
1990年 | 11篇 |
1989年 | 24篇 |
1988年 | 26篇 |
1987年 | 19篇 |
1986年 | 12篇 |
1985年 | 18篇 |
1984年 | 23篇 |
1983年 | 21篇 |
1982年 | 12篇 |
1981年 | 7篇 |
1980年 | 11篇 |
1979年 | 6篇 |
1977年 | 7篇 |
1976年 | 7篇 |
1973年 | 11篇 |
1972年 | 7篇 |
1968年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 940 毫秒
1.
2.
3.
Methods of augmenting bovine mononuclear cell responsiveness during physiological transitions of the udder may enhance resistance of the mammary gland to intramammary infections. Interleukin-2 is required for proliferation of T-lymphocytes and may contribute to B-lymphocyte proliferation. Recombinant bovine interleukin-2 (rBoIL-2) was evaluated as a potential immunoenhancer of bovine mammary gland mononuclear cells. Bovine mononuclear cells were isolated from five primiparous Holstein cows at 14-18 and 28-32 days of involution and at 7-13 days prior to parturition. Bovine blood and mammary gland mononuclear cells were highly responsive to rBoIL-2. Response of mammary gland mononuclear cells to rBoIL-2 was comparable with response of blood mononuclear cells. These data suggest that rBoIL-2 may be an effective immunoenhancer of bovine mononuclear cells during the non-lactating and prepartum periods. 相似文献
4.
H M Syme J C Scott-Moncrieff N G Treadwell M F Thompson P W Snyder M R White J W Oliver 《Journal of the American Veterinary Medical Association》2001,219(12):1725-8, 1707-8
An 11-year-old spayed female Labrador Retriever and a 9-year-old castrated male miniature Poodle were evaluated because of clinical signs of hyperadrenocorticism. Cortisol testing did not support a diagnosis of hypercortisolemia in either dog; however, imaging studies revealed unilateral adrenal tumors in both dogs. Serum concentrations of 17-hydroxyprogesterone, progesterone, and estradiol were high in both dogs, and androstenedione concentrations were also high in 1 dog. It is suspected that sex hormone secretion by the adrenal tumors in these dogs resulted in clinical signs of hyperadrenocorticism. Clinical signs and hormonal abnormalities resolved in the male dog after surgical resection of the tumor. There was no improvement in clinical signs after treatment with mitotane in the female dog, which died 2 months after diagnosis. Histologic evaluation confirmed the presence of adrenocortical carcinoma in both dogs. 相似文献
5.
Michael S. Stone Ian B. Johnstone Marjory Brooks Trent K. Bollinger Susan M. Cotter 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1994,8(1):57-61
A circulating anticoagulant was detected in a 2-year-old Chesapeake Bay Retriever with hemolytic anemia, nephrotic syndrome, thrombocytopenia, polyarthropathy, and pulmonary thromboembolism. A persistent prolongation of the activated partial thromboplastin time (aPTT) was detected, and it did not correct with repeated administration of fresh frozen plasma. The aPTT was still prolonged, with a 1:1 mixture of patient's plasma and normal dog plasma in vitro, suggesting the presence of a circulating inhibitor. Results of assays to characterize the inhibitor were compatible with those described for the lupus anticoagulant in human patients with systemic lupus erythematosus. Paradoxically, patients having the lupus anticoagulant are at increased risk for thrombosis. Pulmonary thromboembolism has been described as a frequent complication of immune-mediated hemolytic anemia in the dog, and the presence of a circulating anticoagulant should be considered as a potential mechanism. 相似文献
6.
M Kachani R A Oliver C G Brown H Ouhelli R L Spooner 《Veterinary immunology and immunopathology》1992,34(3-4):221-234
Western blot analysis of Theileria annulata antigens was carried out using sera collected from cattle which had been immunised and challenged with either T. annulata sporozoites or schizont-infected cells. Three antigens between 71 and 73 kDa proved to be common to the three stages of parasite studied: sporozoites, schizonts and piroplasms. An antigen was found at 32 kDa which was specific to T. annulata piroplasms. Results were reproducible using sera from Morocco and the UK. At least one of the proteins at 71-73 kDa, but not that at 32 kDa were also recognised by sera from animals infected with Babesia species. 相似文献
7.
8.
9.
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
10.
The plasma concentration of hydrocortisone was determined in mares given either cosyntropin (100 IU, given IV) or corticotropin (200 IU, given IM). Plasma hydrocortisone concentrations of the mares treated with cosyntropin increased by 46%, 57% and 80% at 30, 60, and 120 minutes, respectively, when compared with base-line values; these values returned to base line at 240 minutes. In mares treated with corticotropin, mean plasma hydrocortisone concentrations increased by 42%, 143%, 101% and 155% at 30, 60, 120, and 240 minutes, respectively, when compared with base-line values. Differences in total leukocyte count, total eosinophil count, and plasma concentrations of electrolytes (calcium, sodium, magnesium, potassium) of cosyntropin- and corticotropin-treated mares, and these values in control animals were not significant. Results of the present study indicated that the horse responds to small dosages of cosyntropin (IV) in a prompt and reproducible manner as determined by plasma hydrocortisone values. Response to corticotropin was slow and less consistent. Thus, administration of cosyntropin to the horse, according to test results with paired samples collected (before administration and again at 2 hours after injection), was found to be a prompt and meaningful test of adrenal gland function. 相似文献