全文获取类型
收费全文 | 727篇 |
免费 | 53篇 |
国内免费 | 2篇 |
专业分类
林业 | 14篇 |
农学 | 11篇 |
46篇 | |
综合类 | 132篇 |
农作物 | 8篇 |
水产渔业 | 8篇 |
畜牧兽医 | 535篇 |
园艺 | 8篇 |
植物保护 | 20篇 |
出版年
2022年 | 6篇 |
2021年 | 5篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 15篇 |
2017年 | 9篇 |
2016年 | 18篇 |
2015年 | 14篇 |
2014年 | 17篇 |
2013年 | 61篇 |
2012年 | 22篇 |
2011年 | 30篇 |
2010年 | 19篇 |
2009年 | 20篇 |
2008年 | 29篇 |
2007年 | 30篇 |
2006年 | 13篇 |
2005年 | 13篇 |
2004年 | 14篇 |
2003年 | 25篇 |
2002年 | 16篇 |
2001年 | 15篇 |
2000年 | 12篇 |
1999年 | 14篇 |
1998年 | 15篇 |
1997年 | 13篇 |
1996年 | 13篇 |
1995年 | 12篇 |
1994年 | 10篇 |
1993年 | 12篇 |
1992年 | 17篇 |
1991年 | 14篇 |
1990年 | 23篇 |
1989年 | 14篇 |
1988年 | 12篇 |
1987年 | 12篇 |
1986年 | 15篇 |
1985年 | 10篇 |
1984年 | 7篇 |
1983年 | 12篇 |
1982年 | 9篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1975年 | 5篇 |
1974年 | 9篇 |
1973年 | 8篇 |
1972年 | 8篇 |
1971年 | 8篇 |
1970年 | 8篇 |
1969年 | 5篇 |
排序方式: 共有782条查询结果,搜索用时 15 毫秒
11.
Responses of the two‐spotted oak buprestid,Agrilus biguttatus (Coleoptera: Buprestidae), to host tree volatiles 下载免费PDF全文
12.
L R Bramlage S M Reed R M Embertson 《Journal of the American Veterinary Medical Association》1985,186(6):565-567
The medical records and follow-up data for 4 horses with fibrotic myopathy of the semitendinosus muscle treated by semitendinosus tenotomy were reviewed. The gait deficit for each of the 4 horses was typical of fibrotic myopathy. Two of the horses had the gait deficit since birth. The efficacy of semitendinosus tenotomy was compared with the traditional treatment of partial myotenectomy of the affected muscle. The functional results in the 4 horses appeared to be equal to partial myotenectomy in returning the horses to athletic function and, compared with what has been reported, was cosmetically superior. 相似文献
13.
Meadowfoam ( Limnanthes alba) is an oilseed crop grown in western Oregon. The seed meal has potential value as a biopesticide due to glucosinolate degradation products and phytoecdysteroids, a group of polyhydroxylated triterpenoids with potent activities as arthropod molting hormones. Liquid chromatography in combination with tandem mass spectrometry operated in the precursor ion mode revealed the presence of four ecdysteroid glycosides in meadowfoam seed meal. The carbohydrate sequence and the identity of the ecdysteroid aglycones, ponasterone A and 20-hydroxyecdysone, were determined by product ion scanning. Ecdysteroids were detected in the negative ion mode as [M + formate] (-) ions, which yielded [M - H] (-) and alpha-cleavage fragments with retention of hydroxyl groups in MS/MS experiments (not seen in the positive ion mode), allowing the determination of the number of hydroxyl groups in the side chain and in the steroid ring system. MS/MS of glycoside ions ([MH] (+) or [M + formate] (-)) provided carbohydrate sequence information. 相似文献
14.
15.
16.
During a recent investigation of parasites infecting fishes from the Okavango River and Delta, Botswana (southern Africa) fourteen sharptooth catfish, Clarias gariepinus (Burchell, 1822) (Siluriformes: Clariidae) were examined for the presence of myxozoan infections. Results revealed the presence of two species of the genus Henneguya Thélohan, 1895 and one species of the genus Myxobolus Bütschli, 1882 infecting this fish host. Two of the sampled fish exhibited large plasmodia of Henneguya suprabranchiae Landsberg, 1987 in the cartilage of the accessory breathing organ, another two individuals were infected with H. samochimensis sp. n. plasmodia in the gills and another three individuals revealed an infection with Myxobolus gariepinus sp. n. plasmodia in the ovaries. 相似文献
17.
Newer genetic lines of pigs are being used in indoor and outdoor production systems. The objectives of Exp. 1 were to describe the effects of the maternal sow line genotype, environment (indoor vs outdoor), and the genotype x environment interactions on blood hemoglobin (Hb), immunoglobulin G (IgG) concentrations, white blood cell (WBC) numbers, lymphocyte transformation/blastogenesis (LTA), natural killer (NK) cell activity, neutrophil chemotaxis, cortisol concentrations, and leukocyte differentials. Studies were performed using two genotypes: PIC Experimental-94 (Exp-94, an experimental line containing 25% Meishan) and PIC Camborough-15 (C-15). The Exp-94 sows had lower LTA at 0.2 microg/mL mitogen than the C-15 sows, whereas Exp-94 sows had higher NK cytotoxicity than the C-15 sows. When indoors, the two genotypes showed similar neutrophil chemotaxis. When outdoors, the C-15 genotype had higher (P < .01) neutrophil chemotaxis than the Exp-94 sows. The other immune measures were statistically similar for the two genotypes for each environment and for the genotype x environment interaction of sows. Experiment 2 sought to determine the effects of genotype on the immune system of nursery-age offspring of the experimental lines. Each sow line was bred to a common PIC 405 boar line. The Exp-94 x 405 pigs had elevated WBC numbers than C-15 x 405 pigs. The social status of the Exp-94 x 405 or the C-15 x 405 pigs showed no effect on any of the immune measures studied. The other immune measures were statistically similar for the two lines of pigs. The Exp-94 line had marginally increased NK activity but reduced lymphocyte blastogenesis and neutrophil chemotaxis compared with the C-15 line. 相似文献
18.
Adenylyl cyclase amino acid sequence: possible channel- or transporter-like structure 总被引:47,自引:0,他引:47
J Krupinski F Coussen H A Bakalyar W J Tang P G Feinstein K Orth C Slaughter R R Reed A G Gilman 《Science (New York, N.Y.)》1989,244(4912):1558-1564
Complementary DNA's that encode an adenylyl cyclase were isolated from a bovine brain library. Most of the deduced amino acid sequence of 1134 residues is divisible into two alternating sets of hydrophobic and hydrophilic domains. Each of the two large hydrophobic domains appears to contain six transmembrane spans. Each of the two large hydrophilic domains contains a sequence that is homologous to a single cytoplasmic domain of several guanylyl cyclases; these sequences may represent nucleotide binding sites. An unexpected topographical resemblance between adenylyl cyclase and various plasma membrane channels and transporters was observed. This structural complexity suggests possible, unappreciated functions for this important enzyme. 相似文献
19.
Sarah A Reed Joseline S Raja Maria L Hoffman Steven A Zinn Kristen E Govoni 《畜牧与生物技术杂志(英文版)》2014,5(1):43
Background
Maternal over and restricted nutrition has negative consequences on the muscle of offspring by reducing muscle fiber number and altering regulators of muscle growth. To determine if over and restricted maternal nutrition affected muscle growth and gene and protein expression in offspring, 36 pregnant ewes were fed 60%, 100% or 140% of National Research Council requirements from d 31 ± 1.3 of gestation until parturition. Lambs from control-fed (CON), restricted-fed (RES) or over-fed (OVER) ewes were necropsied within 1 d of birth (n = 18) or maintained on a control diet for 3 mo (n = 15). Semitendinosus muscle was collected for immunohistochemistry, and protein and gene expression analysis.Results
Compared with CON, muscle fiber cross-sectional area (CSA) increased in RES (58%) and OVER (47%) lambs at 1 d of age (P < 0.01); however at 3 mo, CSA decreased 15% and 17% compared with CON, respectively (P < 0.01). Compared with CON, muscle lipid content was increased in OVER (212.4%) and RES (92.5%) at d 1 (P < 0.0001). Muscle lipid content was increased 36.1% in OVER and decreased 23.6% in RES compared with CON at 3 mo (P < 0.0001). At d 1, myostatin mRNA abundance in whole muscle tended to be greater in OVER (P = 0.07) than CON. Follistatin mRNA abundance increased in OVER (P = 0.04) and tended to increase in RES (P = 0.06) compared with CON at d 1. However, there was no difference in myostatin or follistatin protein expression (P > 0.3). Phosphorylated Akt (ser473) was increased in RES at 3 mo compared with CON (P = 0.006).Conclusions
In conclusion, maternal over and restricted nutrient intake alters muscle lipid content and growth of offspring, possibly through altered gene and protein expression. 相似文献20.
The diagnosis of eastern equine encephalitis (EEE) virus infection in avian species is relatively difficult when compared with other species. There are no characteristic histologic lesions in the avian brain that would serve to distinguish EEE from infections with, for example, Newcastle disease or highly pathogenic avian influenza virus. Traditionally, virus isolation (VI) and/or hemagglutination inhibition (HI) has been used for a definitive diagnosis of EEE in birds. Recently, we developed an immunohistochemistry (IHC) technique for confirmatory diagnosis of EEE infection in equine brain. This test also detected EEE virus in formalin-fixed avian brain. VI confirmed IHC finding in two cases of EEE in ring-neck pheasants. IHC is a rapid, sensitive test for confirming and differentiating a histopathologic diagnosis of EEE in avian species and should be considered as an alternative test to VI or HI. 相似文献