全文获取类型
收费全文 | 688篇 |
免费 | 24篇 |
专业分类
林业 | 39篇 |
农学 | 107篇 |
基础科学 | 15篇 |
179篇 | |
综合类 | 41篇 |
农作物 | 33篇 |
水产渔业 | 42篇 |
畜牧兽医 | 149篇 |
园艺 | 14篇 |
植物保护 | 93篇 |
出版年
2023年 | 9篇 |
2022年 | 4篇 |
2021年 | 10篇 |
2020年 | 9篇 |
2019年 | 8篇 |
2018年 | 14篇 |
2017年 | 19篇 |
2016年 | 21篇 |
2015年 | 19篇 |
2014年 | 11篇 |
2013年 | 54篇 |
2012年 | 30篇 |
2011年 | 45篇 |
2010年 | 21篇 |
2009年 | 27篇 |
2008年 | 32篇 |
2007年 | 39篇 |
2006年 | 23篇 |
2005年 | 22篇 |
2004年 | 9篇 |
2003年 | 21篇 |
2002年 | 25篇 |
2001年 | 21篇 |
2000年 | 20篇 |
1999年 | 15篇 |
1998年 | 4篇 |
1997年 | 12篇 |
1996年 | 12篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 11篇 |
1992年 | 8篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 15篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 8篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 10篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1969年 | 4篇 |
1968年 | 3篇 |
1967年 | 3篇 |
排序方式: 共有712条查询结果,搜索用时 31 毫秒
71.
Effects of bovine respiratory disease viruses and isoprinosine on bovine leukocyte function in vitro 总被引:1,自引:0,他引:1
Peripheral blood mononuclear cells obtained from 4- to 6-month-old-calves were inoculated in vitro with bovine herpesvirus-1, parainfluenza-3, or bovine virus diarrhea viruses. No increase in infectious virus progeny was observed; however, the viruses were detected in the cells for at least 96 h post-infection without any significant reduction in cell viability. The three viruses, either alone or in combination, suppressed phytohemagglutinin-induced proliferation of the mononuclear cells. The greatest suppression was observed in cultures inoculated with bovine virus diarrhea virus. Addition of isoprinosine partially restored this viral-induced suppression of proliferative response, and the efficiency of reversal was greater in bovine virus diarrhea virus-infected cells. Interleukin-2 activity was higher in cultures of virus-infected mononuclear cells than in cultures of non-infected cells. 相似文献
72.
The surface irrigation system design was formulated as a mathematical programming problem. The minimum cost of a furrow irrigation system for a hypothetical case was calculated for different design depths (25, 51, 76, 102 and 127 mm). The crop yields and net returns were simulated for the given design depths. A design (depletion) depth of 51 mm was found optimal under the given conditions. 相似文献
73.
The glutathione (GSH) -oxidant defence system protects the erythrocytes and leucocytes from oxidative damage. Leucocyte -superoxide dismutase (SOD), GSH-peroxidase (GSH-px), GSH-reductase (GR), GSH-S-transferase (GSH-S-t) and arginase were examined in samples from buffaloes infected with Anaplasma marginale. All the enzymes, except arginase, were also studied in the red cell haemolysates from these animals. GSH-S-t, GSH- and glutathione-reductase (GR) levels in leucocytes decreased in infected animals suggesting a decline in the efficiency of the GSH-oxidant defence system. SOD levels increased but there was no change in leucocyte-arginase activity due to infection. Infection caused no significant changes in red cell SOD, GSH-px, GR and GSH. However, GSH-S-t significantly decreased (P less than 0.05). 相似文献
74.
75.
76.
Nalini Mallikarjuna Deepak R. Jadhav Kanaka Reddy Fatema Husain Kumkum Das 《European journal of plant pathology / European Foundation for Plant Pathology》2012,132(1):17-21
Cultivated groundnut is susceptible to late leaf spot (LLS) caused by Phaeoisariopsis personata [(Berk. & M.A. Curtis) Aex] and resistance is low to moderate in the primary gene pool of groundnut. Closely related wild
species in the secondary gene pool are highly resistant to the disease. All the closely related Arachis species are diploid and cultivated groundnut is a tetraploid. Utilization of diploid Arachis species to transfer LLS resistance is time consuming and cumbersome. New sources of Arachis hypogaea (also called synthetic groundnut) were developed at ICRISAT. These are tetraploids and the present investigation has shown
that they are resistant to LLS. 相似文献
77.
78.
Bheema Lingeswara Reddy Inja Naga Lakshmi Narasu Mangamoori Sivaramakrishnan Subramanyam 《Journal of Crop Science and Biotechnology》2012,15(1):9-16
In recent years, microsatellites have become the most used markers for studying population genetic diversity. The increased
availability of the DNA sequences has given the possibility to develop EST-derived SSR markers. A total of 1,927 ESTs of Eleusine coracana available in the NCBI database were mined for SSRs. Di-nucleotides are the most occurring motifs accounting for more than
50% of the repeats, of which GA was the most abundant motif and tetra-nucleotides are the least occurring motifs. Of the 132
markers identified, 30 primer pairs based were synthesized. SSR markers were used for variety discrimination and genetic assessment
in 15 finger millet accessions; 20 primers showed polymorphism and 13 primers were identified as having a PIC value above
0.5. On the basis of the distribution of these polymorphic alleles, the 15 accessions were classified into two groups. This
study has demonstrated the potential of EST-derived SSR primer pairs in finger millet. These primers will serve as valuable
source for further breeding programs. 相似文献
79.
Haunshi S Shanmugam M Padhi MK Niranjan M Rajkumar U Reddy MR Panda AK 《Tropical animal health and production》2012,44(5):969-973
The present study was conducted to evaluate two Indian native chicken breeds, namely, Aseel and Kadaknath for fertility, hatchability,
genetic parameters of juvenile growth traits, and semen quality traits at the onset of sexual maturity. The fertility was
similar in Aseel (86.96%) and Kadaknath (85.15%); however, a relatively higher hatchability was observed in Kadaknath (77.94%)
than Aseel (70.74%). Heritability estimates of body weights at 4 weeks of age were almost similar in Aseel (0.37) and Kadaknath
(0.39), while the estimate of body weight at 6 weeks of age was higher in Aseel (0.42) than Kadaknath (0.31). The heritability
estimate of shank length at 6 weeks of age was lower in Aseel (0.16) compared to Kadaknath (0.35). The age at first egg in
the flock was comparable in Aseel (148 days) and Kadaknath (150 days). Aseel breed with significantly (P ≤ 0.001) higher body weight, absolute and relative testes weights had significantly higher semen volume (P ≤ 0.05) and sperm motility (P ≤ 0.01) but had lower seminal plasma cholesterol level (P ≤ 0.05) as compared to Kadaknath. It can be concluded that there is a scope for genetic improvement of these two native breeds
for juvenile growth traits since heritability estimates of these traits were relatively high. 相似文献
80.
Reddy IJ David CG Selvaraju S Mondal S Ravi Kiran G 《Tropical animal health and production》2012,44(6):1311-1317
The objective of this was to establish the effects of red spectrum of light (650 nm, treated n = 12) and normal spectrum of light (450 nm control = 12) on GnRH-I mRNA expression, amplitude and frequency of luteinizing hormone (LH), and egg production from 72-82 weeks of age in white leghorn hens. Birds exposed to red spectrum of wavelength significantly improved (P < 0.01) steroid hormone, and egg production improved over old laying 72 to 82 weeks. Weekly interval profiles followed the same pattern. At 77th weeks of age blood, samples from both the groups were collected at every 3 h for 36 h to study the pulsatile secretion of LH surges. Plasma LH concentration was higher (P < 0.01) in treated birds with more number of frequencies and amplitude LH surges in plasma of treated birds. LH frequencies were more pronounced and advanced during 36 h of sampling at 3 h interval in treated birds. Weekly interval of plasma LH, E2β, and P(4) concentrations increased (P < 0.01) in treated birds from 72 to 82 weeks of age. GnRH-I mRNA concentration was significantly (P < 0.01) higher in birds exposed to red spectrum of light compared to controls. It is hypothesized that exposure of birds to red spectrum of light-enhanced (P < 0.01) GnRH-I mRNA with more number of yellow yolky follicles was found in birds exposed to red spectrum of light during 77 days (72-82 weeks of age) of experimental period. It is concluded that higher levels of GnRH-I mRNA, LH, E2β, and P(4) concentration with lower incidence of pause days enabled the birds to lay more eggs even later in the productive period by modulating the wavelengths of light under normal husbandry conditions. 相似文献