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排序方式: 共有202条查询结果,搜索用时 31 毫秒
1.
Alla M. Gol’Berg Shoshana Yathom Ahuva ALmogi-Labin G. Fridland-Wunder 《Phytoparasitica》1989,17(2):81-89
Adult populations ofMaladera matrida Argaman (Coleoptera: Scarabaeidae), a beetle highly injurious to agricultural crops, were studied in the coastal plain of Israel from 1985 to 1988. There were two generations annually. Adults emerged in March, April or May and disappeared in October or November. The beetles are on the wing, mate, and feed at twilight and in the dark. Feeding and mating behavior, sex ratio, and preferred food plants were studied. 相似文献
2.
During June to September 1992, a special campaign was held to measure rapid changes in Earth's rotation rate and to relate these measurements to variations in the atmosphere's angular momentum, due principally to changes in zonal winds. A strong rise in both length of day and atmospheric momentum during a particular 6-day subperiod is documented, and this example of a short-period perturbation is identified with a specific regional coupling mechanism. Mountain torques within the southern tropics appear to account for most of the rapid momentum transfer between the solid Earth and atmosphere, with those across South America especially important. 相似文献
3.
Rosen GD 《British poultry science》2007,48(1):27-32
1. This holo-analysis of the effects in turkey nutrition of Bio-Mos(R) (BM) (Alltech Inc., Nicholasville, KY) aims to elaborate comprehensive empirical models for the assessment of responses under practical conditions and for its comparison with other potential pronutrient antibiotic replacements. 2. The data bank utilised was obtained from 54 publications on BM in turkeys from a total collection of 57 papers (1995-2003) on the use of saccharide products as turkey feed additives. These yielded 33 start-to-finish negatively-controlled feed intake, liveweight gain and feed conversion and 24 mortality effects in the USA, France and Poland, using 12,723 birds with a mean of 212 birds per treatment. 3. The feed, gain, conversion and mortality responses to BM compared with the relevant negative controls average -243 g, 57.0 g, -0.0156 and 1.29% with coefficients of variation of 451, 451, 705 and 426%, respectively. Beneficial gain, conversion and mortality effects were found in 52, 52 (33% jointly) and 52% of the tests, respectively. 4. Holo-analytical multiple regression models comparing conventional Por=0.10 out and less stringent Por=0.34 out partial regression coefficient standards, with and without>or=1.5xroot mean square error outliers, contain significant independent variables for negative control performance, duration, year of test, not-USA test, discontinuous dosage, cage housing, mash feed, feed antibiotic, feed anticoccidial, disease condition and high control (>10%) mortality. 5. These developmental models indicate fruitful pathways for future developments with an accent on the definition of specific dose-response relationships, whilst also confirming the value and future potential for BM in turkey production in praxis. 相似文献
4.
Navarre WW Porwollik S Wang Y McClelland M Rosen H Libby SJ Fang FC 《Science (New York, N.Y.)》2006,313(5784):236-238
Horizontal gene transfer plays a major role in microbial evolution. However, newly acquired sequences can decrease fitness unless integrated into preexisting regulatory networks. We found that the histone-like nucleoid structuring protein (H-NS) selectively silences horizontally acquired genes by targeting sequences with GC content lower than the resident genome. Mutations in hns are lethal in Salmonella unless accompanied by compensatory mutations in other regulatory loci. Thus, H-NS provides a previously unrecognized mechanism of bacterial defense against foreign DNA, enabling the acquisition of DNA from exogenous sources while avoiding detrimental consequences from unregulated expression of newly acquired genes. Characteristic GC/AT ratios of bacterial genomes may facilitate discrimination between a cell's own DNA and foreign DNA. 相似文献
5.
G J Collins J D Rosen 《Journal of the Association of Official Analytical Chemists》1979,62(6):1274-1280
A method for the analysis of T-2 toxin in milk is presented. Ethyl acetate extracts of milk samples which had been spiked with T-2 toxin were purified by thin layer chromatography and derivatized with N,O-bis(trimethylsilyl)acetamide to produce the T-2 toxin trimethylsilyl ether (T-2 toxin-TMS). N,O-bis(trimethylsilyl-d9)acetamide was used to make T-2 toxin d9-trimethylsilyl ether (T-2 toxin-d9 TMS) which was added to the derivatized milk extract as an internal standard. Samples were analyzed by combined gas-liquid chromatography/mass spectrometry using either electron impact ionization or chemical ionization mass spectrometry. In electron impact ionization analyses, simultaneous monitoring of the T-2 toxin-TMS fragment ion at m/z 436 and the T-2 toxin-d9TMS fragment ion at m/z 445 gave a T-2 toxin-TMS detectability estimated at 6 microgram/kg. In chemical ionization analyses, the T-2 toxin-TMS fragment ion at m/z 377 and the T-2 toxin-d9TMS fragment ion at m/z 386 were simultaneously monitored to give a T-2 toxin-TMS detectability estimated at 3 microgram/kg. Average recovery was 85% at 200 microgram/kg and 65% at 20 microgram/kg. 相似文献
6.
A study was carried out to determine the distribution of feeding and oviposition punctures made byLiriomyza trifolii Burgess on gypsophila(Gypsophila paniculata ) and bean(Phaseolus vulgaris) leaves, and the development times of the immature stages on these plants. The absolute number of punctures per leaf area
was much greater on bean leaves than on gypsophila leaves. The number of mines per leaf was also higher on beans than on gypsophila,
but the ratio of mines/punctures was higher on gypsophila. Gypsophila leaves were punctured on both sides, but most of the
punctures were on the distal third of the upper leaf side. On beans the punctures were dispersed uniformly on the upper side
of the leaf. The larval period (±SE) at temperatures of 20, 25 and 30°C was 9.9±0.2, 4.4±0.1 and 3.7±0.1, and 5.5±O. l, 3.7±0.1
and 2.4±0.1 days, on gypsophila and bean, respectively. The pupal period at 17, 20, 25 and 30°C lasted 19.9±0.2, 14.7±0.1,
10.4±0.1 and 7.8±0.1 days, respectively. 相似文献
7.
The effects of γ-radiation on the immature stages ofLiriomyza trifolii Burgess were studied with doses of 2000-25 Gy. The high doses were lethal to all stages. At doses of 750 Gy or less, larvae
survived to pupate, but their number was reduced and the majority were either dead or deformed and did not give rise to adults.
Eggs and prepupae were more susceptible to radiation than other stages. Larval radiosensitivity decreased with progressing
instar, and pupal sensitivity decreased with increasing age.
Contribution from the Agricultural Research Organization. No. 2922-E, 1990 series. 相似文献
8.
9.
F. Widén H. Everett S. Blome J. Fernandez Pinero Å. Uttenthal M. Cortey T. von Rosen M. Tignon L. Liu 《Research in veterinary science》2014
Classical swine fever is one of the most important infectious diseases for the pig industry worldwide due to its economic impact. Vaccination is an effective means to control disease, however within the EU its regular use is banned owing to the inability to differentiate infected and vaccinated animals, the so called DIVA principle. This inability complicates monitoring of disease and stops international trade thereby limiting use of the vaccine in many regions. The C-strain vaccine is safe to use and gives good protection. It is licensed for emergency vaccination in the EU in event of an outbreak. Two genetic assays that can distinguish between wild type virus and C-strain vaccines have recently been developed. Here the results from a comparison of these two real-time RT-PCR assays in an interlaboratory exercise are presented. Both assays showed similar performance. 相似文献
10.