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31.
32.
Miller FG 《Science (New York, N.Y.)》2004,304(5674):1109-11; author reply 1109-11
  相似文献   
33.
34.
Molecular defect in a gamma-2 heavy chain   总被引:9,自引:0,他引:9  
The first gamma-2 (gamma2) heavy chain disease protein Gif has pyrroli-dinecarboxylic acid as its amino terminal residue, much of the Fd variable region, and an internal deletion of the heavy chain of about 100 residues corresponding to most of the Fd constant region. Normal sequence resumes with a glutamic acid residue at position 216 in the hinge region. This is the third gamma heavy chain disease protein where normal sequence resumes at the same position after the deletion.  相似文献   
35.
Long- and short-term direct-drilling and seed broadcasting plus rotovation were examined as possible quick and cheap alternatives to conventional mouldboard ploughing and drilling. The experiment was the continuation of an existing long-term tillage experiment for spring barley. The conventional ploughing and long-term direct-drilling treatments continued on the same plots. The broadcasting and the short-term direct-drilling treatments were applied to previously chisel-ploughed and deep mouldboard-ploughed treatments, respectively. Autumn nitrogen treatments of 30 or 60 kg ha−1 and spring nitrogen treatments of 150 or 225 kg ha−1 were applied. The experiment is located on a cambisol (15% clay in topsoil) and on a gleysol (17% clay in topsoil) in south-east Scotland. Straw was removed by baling and the stubble remained when the treatments were applied.

Long-term direct-drilling yielded most over the 3 years of the experiment and was particularly successful after the unusually wet autumn and winter of the third season. Short-term direct-drilling was the lowest yielding treatment in the first season only. The success of the long-term direct-drilling treatment was associated with the development of a stable, protective surface tilth as a result of organic-matter accumulation. This was associated with some soil structural improvement deeper in the profile in the long-term direct-drilled gleysol as shown by measurements of air permeability. Crop performance apparently was not related to soil compactness or cone resistance. The relatively high rates of nitrogen applied, both autumn and spring, gave worthwhile crop responses except for the third season, when the crop lodged. Short-term direct-drilling, broadcasting with rotovation and ploughing with drilling gave similar average yields on the gleysol, but on the cambisol broadcasting with rotovation outyielded the other two treatments by an average of 0.3 t ha−1.  相似文献   

36.
The metabolism of α-pinene, a major monoterpene in Pinus spp. in the United States, has been examined utilizing microsomal fractions from larval and adult Dendroctonus terebrans and rat liver. Under hydroxylating conditions, both insect and rat liver microsomes convert α-pinene into α-pinene oxide and several other undentified products. α-Pinene oxide was identified by mass spectrometry. α-Pinene is an inducer of cytochrome P-450 in rat liver microsomes and its effect on the pattern of α-pinene metabolism is very similar to β-naphthoflavone. No increase in cytochrome P-450 was observed when insects were treated with α-pinene; however, the quantity of α-pinene metabolic products was increased by α-pinene pretreatment. The role of cytochrome P-450 linked reactions in the production of insect pheromones via the α-pinene epoxide intermediate is discussed.  相似文献   
37.
Wild caught Asian catfish were spawned manually following HCG injection, and a portion of the eggs were subjected to cold-shock at 4 C for 15 min within 2-min post-fertilization. Nuclear diameter measurements of cold-shocked fish revealed that 96% were triploids (3N), while non-shocked fish were all diploids (2N). During larval and fry culture (first 26 d), triploid fish mortality was =50%, while diploid mortality was =25%. Following 8-mo culture in tanks at three stocking densities, triploid fish survival was significantly greater ( P < 0.05), than diploids, with 84.0% and 57.3%, respectively. Triploid live weight was also significantly greater than diploids, with 69.2 and 45.9 g averages, respectively. Ninety-two percent of diploids had welldeveloped gonads after 8 mo; whereas none of the triploids had mature gonads. Gonads were undifferentiated with 31% of the triploids. These sexually undifferentiated fish had greater growth rates than male or female triploids, and greater growth than all diploids. Carcass weight (gutted) of triploids was 95.8% of live weight, compared with 92.5% for diploids. Lastly, triploids had very few deformities compared with diploids, with 1.3% and 17.6%, respectively. Deformities included curved spines, and humped backs just posterior of the head.  相似文献   
38.
Induction of IL-2 and lymphokine activated killer cells in the cat   总被引:4,自引:0,他引:4  
We have described the use of a cloned murine IL-2-dependent T-cell line to directly measure feline IL-2. Concanavalin A stimulated feline peripheral blood lymphocytes produced an IL-2-rich supernatant that supported the growth of this murine IL-2-dependent T-cell line. In addition to producing IL-2, Con A stimulated killer cells in PBL were cytotoxic for the FeLV transformed tumor cell line FL74. Incubating feline PBL with a cocktail of the calcium ionophore A23187 and phorbol ester also led to the generation of cytotoxic cells as well as the production of high levels of IL-2. Finally, IL-2-rich supernatant was able to stimulate cytotoxic activity in PBL from normal cats.  相似文献   
39.
The minimum inhibitory concentration (MIC) of ten antimicrobial drugs for 287 S. aureus strains recently isolated from bovine mastitic milk in different herds all over Sweden was determined. The minimum bactericidal concentration (MBC) of benzylpenicillin for 20 strains was determined. Thirty strains (10%) produced beta-lactamase. All strains were susceptible to oxacillin and neomycin, and more than 90% to streptomycin, trimethoprim-sulphamethoxazole chloramphenicol, erythromycin and tetracycline, whereas all were resistant to sulphamethoxazole. None of 20 strains investigated was tolerant to benzylpenicillin. However, S. aureus strains, isolated from bovine milk, should be tested for beta-lactamase production prior to treating mastitic cases with beta-lactam drugs.  相似文献   
40.
Recent developments of new families of pesticides and growing awareness of the importance of wild pollinators for crop pollination have stimulated interest in potential effects of novel pesticides on wild bees. Yet pesticide toxicity studies on wild bees remain rare, and few studies have included long-term monitoring of bumble bee colonies or testing of foraging ability after pesticide exposure. Larval bees feeding on exogenous pollen and exposed to pesticides during development may result in lethal or sub-lethal effects during the adult stage. We tested the effects of a naturally derived biopesticide, spinosad, on bumble bee (Bombus impatiens Cresson) colony health, including adult mortality, brood development, weights of emerging bees and foraging efficiency of adults that underwent larval development during exposure to spinosad. We monitored colonies from an early stage, over a 10-week period, and fed spinosad to colonies in pollen at four levels: control, 0.2, 0.8 and 8.0 mg kg(-1), during weeks 2 through 5 of the experiment. At concentrations that bees would likely encounter in pollen in the wild (0.2-0.8 mg kg(-1)) we detected minimal negative effects to bumble bee colonies. Brood and adult mortality was high at 8.0 mg kg(-1) spinosad, about twice the level that bees would be exposed to in a 'worst case' field scenario, resulting in colony death two to four weeks after initial pesticide exposure. At more realistic concentrations there were potentially important sub-lethal effects. Adult worker bees exposed to spinosad during larval development at 0.8 mg kg(-1) were slower foragers on artificial complex flower arrays than bees from low or no spinosad treated colonies. Inclusion of similar sub-lethal assays to detect effects of pesticides on pollinators would aid in development of environmentally responsible pest management strategies.  相似文献   
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