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91.
Effects of sterol biosynthesis-inhibiting (SBI) fungicides on cytochrome P-450 oxygenations in fungi
The fungicides miconazole, fenarimol, and etaconazole block ergosterol biosynthesis in fungi by inhibiting sterol 14α-demethylation, which is mediated by a cytochrome P-450 enzyme. The sensitivity of cytochrome P-450-dependent hydroxylation or demethylation of several substrates to these fungicides and similar compounds was compared to that of fungal growth and sterol 14α-demethylation. Demethylation of p-chloro-N-methylaniline (PCMA) by sporidia of Ustilago maydis and 11α-hydroxylation of progesterone by Aspergillus nidulans were relatively insensitive to these compounds and to metyrapone. The ability of a sterol 14α-demethylation-deficient mutant to demethylate PCMA indicates that this substrate is not demethylated by the sterol 14α-demethylation system of U. maydis. The 14α-hydroxylation of progesterone by cells of Curvularia lunata was quite sensitive to the three fungicides, and also to metyrapone and isopropylphenylimidazole. This system was less sensitive to the three fungicides than sterol 14α-demethylation, but was appreciably more sensitive than PCMA demethylation. A study of progesterone 14α-hydroxylation in cell-free preparations of C. lunata showed the reaction to be inhibited by CO, and to be competitively inhibited by low concentrations of miconazole. These data suggest that the primary action of sterol biosynthesis-inhibiting (SBI) fungicides is competitive inhibition of sterol/steroid-type cytochrome P-450 enzymes rather than interference with the function of sterol carrier proteins or enzyme-modulating phospholipids. 相似文献
92.
Henry Sgaard 《Acta veterinaria Scandinavica》1975,16(3):388
It has been studied whether R factor transfer had an inhibitory effect on the growth rate of Escherichia coli in mixed cultivation. A total of 39 antibiotic resistant E. coli strains were grown together with E. coli K12 W 3132 as prospective recipient. Thirteen crosses turned out successfully. When comparing generation times for these crosses with those of negative crosses no difference could be demonstrated. This, however, does not exclude that R factor transfer impairs bacterial growth capacity at a level which can not be detected in a short-term experiment. 相似文献
93.
Rectal transmission of bovine leukemia virus in cattle and sheep 总被引:2,自引:0,他引:2
Bovine leukemia virus (BLV) was transmitted by rectal inoculation of BLV-infective whole blood into cattle and sheep. Two cows and 2 sheep each were given 500 ml and 50 ml of blood, respectively, by rectal infusion. Two sheep which served as positive controls each were given 1 ml of the same blood, IV. All animals became seropositive to BLV by postinoculation week 5. Although relatively large volumes of blood were used for rectal inoculation, a base line for infectivity was established for the rectal route. 相似文献
94.
Ammonium thiocyanate ( I ) was shown to inhibit the oxidation of aminotriazole (3-amino-1,2,4-triazole) in two free-radical generating systems: (a) riboflavin photo-sensitised oxidation; and (b) oxidation by hydroxyl radicals. Evidence from in-vitro studies is presented to show that I could enhance aminotriazole performance by being preferentially oxidised within the leaf, thereby preventing aminotriazole free-radical formation and subsequent conjugation with amino acids and other compounds. This opens up the possibility of a whole new range of additives which could enhance translocation by inhibiting free-radical reactions. A comparison of possible inhibitors revealed that cyanides, iodides and perhaps bromides may be of use in this respect. In addition to inhibiting free-radical reactions, I and potassium iodide ( II ) were shown to have a considerable effect on the uptake of aminotriazole by bean leaves (Phaseolus vulgaris var. Canadian Wonder). In the absence of additives, uptake of aminotriazole was negligible (1.8%); in the presence of a 1:1 molar ratio of I or II , uptake of aminotriazole was increased to 36.6% and 54.2% respectively. At a 3:1 molar ratio of additive:aminotriazole, the respective figures were 63.5% and 81.0%. II appeared to be the more efficient of the two additives at higher humidity. However, the results and observations indicated that the situation may be reversed under low-humidity conditions. 相似文献
95.
96.
The process of obtaining a veterinary medical education creates a number of potential cognitive, emotional, physical, interpersonal, and developmental stressors for veterinary students. Although most universities offer stress management interventions for their students, these programs are often directed toward undergraduate students or non-veterinary graduate students, whose educational programs differ significantly from those of veterinary students. There is a need for specific stress management programs tailored to the needs of veterinary students. This article summarizes research drawn from the psychology, medical, and veterinary medical literature about the causes of stress that veterinary students experience. Interventions are discussed, and several Oregon State University (OSU) programs and liaisons are described. Stress management resources are suggested. 相似文献
97.
Mihalis Cutrubinis Henry Delincée Mario Stahl Olaf R?der Hans Jürgen Schaller 《Gesunde Pflanzen》2005,224(4):129-136
Saatgut und Getreide kann mit niederenergetischen Elektronen (<300 kev) oder=" hochenergetischen=" elektronen=" (1–10 mev)=" wirksam=" behandelt=" werden,=" um=" mikroorganismen=" und=" insekten=" abzutöten.=" in=" dieser=" vorläufigen=" studie=" wurde=" mais=" mit=" niederenergetischen=" (125 kev)=" und=" hochenergetischen=" elektronen=" (10 mev)=" behandelt.=" um=" diese=" elektronenbehandlung=" nachzuweisen,=" wurden=" verschiedene=" verfahren=" eingesetzt:=" photostimulierte=" lumineszenz=" (psl),=" thermolumineszenz=" (tl)=" und=" dna-kometentest.=" für=" diese=" drei=" nachweismethoden=" existieren=" bereits=" europäische=" normen=" und=" sie=" sind=" als=">300 kev)>Allgemeine Codex Methoden zum Nachweis bestrahlter Lebensmittel etabliert. Die Ergebnisse zeigen, dass PSL und TL geeignete Verfahren sind, um sowohl eine Behandlung von Mais mit niederenergetischen als auch mit hochenergetischen Elektronen zu erkennen. Der DNA-Kometentest erwies sich als weniger geeignet: die Behandlung mit niederenergetischen Elektronen konnte—wie erwartet—nicht nachgewiesen werden. Die Behandlung mit hochenergetischen Elektronen konnte bei einer Maissorte erkannt werden, jedoch nicht bei einer anderen Sorte. 相似文献
98.
Henry Sgaard 《Acta veterinaria Scandinavica》1975,16(1):31
Of 178 strains of E. coli isolated on non-selective medium from faeces of pigs and humans living in the same farm 14 produced hydrogen sulphide. The H2S producing variants all belonged to different clones suggesting that the H2S character was plasmid-mediated. Attempts to transfer the H2S character were not successful nor were attempts to motilize the gene by introduction of a transmissible R factor. 相似文献
99.
100.