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991.
Telomere shortening in normal somatic cells has been proposed as a major barrier to unlimited cellular proliferation. Telomerase is an enzyme capable of maintaining telomere length, and thus bypassing this barrier. In human beings, telomerase activity is restricted to cancer cells and cells of stem or germ cell lineages. Dogs represent a potentially useful clinical model for the development of telomerase‐based therapies because telomerase activity is also restricted to cancer cells and stem cells in this species. We examined the ability of telomestatin to inhibit telomerase activity in telomerase‐positive D17 and CMT7 canine cancer cell lines. At a concentration of 2 μM, telomestatin treatment resulted in a decrease in telomerase activity, telomere shortening, growth inhibition and apoptosis in telomerase‐positive cancer cells. These effects were not seen in telomerase‐negative skin fibroblasts or negative controls. These results confirm that telomestatin specifically inhibits telomerase activity in canine cancer cells and strengthens the usefulness of dogs as a model for testing telomerase‐based therapies. 相似文献
992.
Summary Seven and a half thousand wheat varieties, including over 2,000 durums, were screened for resistance to Septoria tritici under conditions of artificial inoculation in the field. From this screening, 460 varieties were selected on the basis of resistance and earliness and were subject to more detailed observation.Selected varieties were tested in the field with two replications under both natural and artificial epidemic conditions. The agreement between varietal scores in the two replications and under the two conditions was good; 91–94% of varieties showing consistent disease scores. The correlation coefficient between varietal scores for the natural epidemic and the artificial epidemic conditions was 0.63***.A number of the very early maturing varieties of T. aestivum showed good resistance as measured by pycnidial production but exhibited extensive leaf necrosis. This reaction was not observed in later varieties and in accessions of T. durum.Varieties of Triticum durum were typically more resistant than varieties of T. aestivum. Thirty-four varieties of T. aestivum and 266 varieties of t. durum showed a consistent expression of resistance. A list of these 34 accessions of T. aestivum and selected accessions of T. durum is provided, along with agronomic data. 相似文献
993.
Tuta absoluta (Meyrick) is an invasive pest of tomato native to South America, where it is responsible for extensive damage. It rapidly spread into several European countries, becoming a key pest. Knowledge of its main biological traits can be used to develop effective plant protection management strategies. It is a multivoltine species with a homodynamous behaviour, and the length of its life cycle depends on environmental conditions, particularly temperature. The larvae feed and develop inside tomato leaves, stems and fruits throughout the entire growing cycle. The adults have crepuscular habits, and in Mediterranean conditions they can be easily detected throughout the year. Damage is directly related to the reduction of plants' photosynthetic capacity and of production levels in both protected and open‐field tomato crops; indirect damage can be also caused by secondary infections, with pathogens developing on the infested plant and fruit tissues. 相似文献
994.
R B Truscott O Onoviran H L Ruhnke N A Fish C A Barker 《Canadian journal of veterinary research》1975,39(4):416-420
The in vitro antimicrobial sensitivity of 14 mycoplasma and 13 ureaplasma strains isolated from the genital tracts of bulls was examined. It was found that at relatively low concentrations, tetracycline, declomycin and tylosin were lethal to both types of organisms. Lincospectin, berenil, streptomycin and erythromycin were lethal to mycoplasmas but were only inhibitory to the ureaplasma strains at the same concentrations. Polymyxin B and novobiocin were ineffective at the levels tested. 相似文献
995.
ABSTRACT Coverless petri dishes with water suspensions of sporangia and zoospores of Phytophthora infestans were embedded in sandy soil in eastern Washington in July and October 2001 and July 2002 to quantify longevity of spores in water under natural conditions. Effects of solar radiation intensity, presence of soil in petri dishes (15 g per dish), and a 2-h chill period on survival of isolates of clonal lineages US-8 and US-11 were investigated. Spores in water suspensions survived 0 to 16 days under nonshaded conditions and 2 to 20 days under shaded conditions. Mean spore survival significantly increased from 1.7 to 5.8 days when soil was added to the water. Maximum survival time of spores in water without soil exposed to direct sunlight was 2 to 3 days in July and 6 to 8 days in October. Mean duration of survival did not differ significantly between chilled and nonchilled sporangia, but significantly fewer chilled spores survived for extended periods than that of nonchilled spores. Spores of US-11 and US-8 isolates did not differ in mean duration of survival, but significantly greater numbers of sporangia of US-8 survived than did sporangia of US-11 in one of three trials. 相似文献
996.
Carnagey KM Huff-Lonergan EJ Lonergan SM Trenkle A Horst RL Beitz DC 《Journal of animal science》2008,86(7):1637-1648
The objective of this trial was to determine how 25-hydroxyvitamin D(3) (25-OH D(3)) supplementation, altering supplemental dietary calcium, or their combination influence postmortem biochemical and tenderness changes in muscles from the round of mature cows. Twenty-seven Angus cows (3 to 7 yr old) were allotted randomly to 9 pens with 3 cows per pen. Treatments were arranged in a 3 x 3 factorial design with 3 dosages of 25-OH D(3) (0, 250, or 500 mg of 25-OH D(3) administered as a 1-time oral bolus 7 d before slaughter) and 3 percentages of supplemental limestone (0.5, 0.75, and 1.0%) replenished in the diet for 3 d before slaughter and after a 2-wk limestone withdrawal. Plasma samples were obtained during the feeding period. Upon slaughter, adductor, gracilus, pectineus, sartorius, semimembranosus, vastus intermedius, and vastus lateralis muscles were obtained and aged for 1, 3, or 7 d. Calcium concentrations were increased in plasma when 250 or 500 mg of 25-OH D(3) were administered (P = 0.05). Calcium concentrations in muscle increased (P = 0.001) when 500 mg of 25-OH D(3) were administered. Concentrations of 25-OH D(3) in meat and in plasma and 1,25-dihydroxyvitamin D(3) [1,25-(OH)(2) D(3)] in plasma were increased when 25-OH D(3) was administered (P = 0.05). The percentage of limestone replenished in the diet had no effect on 25-OH D(3) or 1,25-(OH)(2) D(3) in meat or in plasma. Calpastatin activity was affected by treatments only in the gracilus and vastus intermedius muscles (P = 0.05). Among all muscles and aging periods, calpastatin activity and intensity of troponin-T degradation product were related inversely. Results indicate that supplemental 25-OH D(3) has some influence on muscle characteristics known to improve tenderness, but improved tenderness was not observed. 相似文献
997.
998.
We studied the ability of lambs to select safe foods in the presence of harmful foods. In a series of feeding experiments, 3- to 6-mo-old lambs were offered a choice between 1) a familiar, safe and a novel, harmful food, 2) a novel, safe and a novel, harmful food and 3) a familiar, harmful and a novel, safe food. All harmful foods were palatable feeds that had been treated with lithium chloride (LiCl), a non-lethal gastrointestinal poison. When lambs ingested a meal composed of a novel food containing LiCl and a familiar, safe food, lambs subsequently avoided the novel food. Lambs avoided the novel food even when the familiar food contained LiCl. The response of lambs varied when lambs were given a choice between a novel, safe food and a novel food containing LiCl. Lambs either avoided the novel food containing LiCl and ingested the safe food or they limited their intake of both novel foods. Their response was dependent on the novelty of the food containing LiCl. When a novel, palatable food contained 2% LiCl, lambs always ate some of the food, even after experiencing illness from ingesting it. Lambs experienced with foods containing LiCl displayed greater food neophobia than lambs naive to LiCl-treated foods. Thus, novelty was the major criterion that lambs used to associate foods with gastrointestinal illness. 相似文献
999.
A. T. Szabó 《Genetic Resources and Crop Evolution》2010,57(3):471-472
1000.
Janusz A Madej Jan P Madej Piotr Dziegiel Bartosz Pula Marcin Nowak 《Acta veterinaria Scandinavica》2013,55(1):73