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31.
Calcium channels were studied in isolated spontaneously rhythmic rabbit jejunum using the muscarinic agonist carbachol as stimulant. Carbachol failed to produce the characteristic phasic and tonic components of smooth muscle contractions. A variety of chemically distinct calcium antagonists, viz. bepridil, diltiazem, isradipine (PN 200-110), nifedipine, and verapamil, non-competitively inhibited the contractions. Diltiazem was most potent (-logIC50 = 8.30) and bepridil least potent (-logIC50 = 6.19) in inhibiting the contractions. The findings conclude with the presence of pharmacologically distinct receptor-operated calcium-channels, besides the potential-dependent calcium-channels, in the rabbit jejunum. 相似文献
32.
A microtiter plate-based enzyme immunoassay has been developed for phaseolinone, a phytotoxin isolated from the culture filtrate of the plant-pathogenic fungus Macrophomina phaseolina (Tassi) Goid. The smallest amount of phaseolinone detectable by the method is 5 pg per well. The method is validated by comparison with high-performance liquid chromatography and used to confirm and estimate phaseolinone production in seeds infected with the fungus. The degree of seed inhibition correlated well with the amount of toxin produced in infected seeds, 50% inhibition being observed at a toxin concentration of 0.60 micrograms/g of wet tissue. 相似文献
33.
G. M. Shah U. C. Goswami R. K. Bhattacharya 《Journal of biochemical and molecular toxicology》1992,7(3):177-181
Several vitamin A compounds have been tested for their ability to suppress formation of DNA adduct by the carcinogen benzo[a]pyrene (B[a]P) in an in vitro reaction catalyzed by rat liver microsomes. Retinol, retinal, 3-dehydroretinol and 3-hydroxyretinol were found to be effective inhibitors of adduct formation. Certain carotenoids that are precursors of these retinoids also displayed considerable inhibitory capacity. Carotenoids and the 3-substituted retinoids appeared to modulate the DNA adduct formation exclusively through their action on microsomal enzymes, since an effective inhibition in each case was observed on the formation of B[a]P-7,8-diol, a proximate carcinogenic metabolite of B[a]P. Unsubstituted retinoids, on the other hand, had marginal effect on enzymes but were found effective in accelerating inactivation of B[a]P-7,8-diol-9,10-epoxide, the ultimate carcinogenic metabolite that binds to DNA. 相似文献
34.
Effects of a selective monoamine oxidase (MAO)--A inhibitor, clorgyline, a selective MAO-B inhibitor, deprenyl, and a non-selective MAO inhibitor, nialamide, were investigated on footshock-induced aggression (FIA) in paired rats. The doses and pretreatment times of the inhibitors used were based on an earlier reported in vivo dose-response and time-course study. In addition, apomorphine, a dopaminergic receptor agonist, and beta-phenylethylamine, a preferred substrate for MAO-B, were also used to garner corroborative evidence. The results of the study indicate that selective MAO-A inhibitors are likely to attenuate FIA by augmenting central serotonergic activity, while selective MAO-B inhibitors accentuate the behaviour by facilitating dopaminergic activity. A permissive role for noradrenaline could not be delineated by the available data. 相似文献
35.
G Mukherjee D Banerjee D K Bhattacharya G C Chatterjee 《Indian journal of experimental biology》1990,28(6):550-552
Collagen stimulation of blood platelets resulted in significant increases in malondialdehyde (MDA) formation and activity of glucose-6-phosphate dehydrogenase (G6PDH) and a decrease in catalase and glutathione peroxidase (GPx). Retinoic acid (RA) pretreatment did not show any appreciable changes except for a decrease in G6PDH activity as compared with collagen alone. RA pretreatment of human blood platelets resulted in an increase in the activities of catalase and GPx, two important radical scavenging enzymes, with significant decrease in MDA formation when compared with ADP alone. It is suggested that RA has a significant effect on the antioxidant defence system in ADP stimulated platelets but not in the collagen stimulated platelets. 相似文献
36.
S K Bhattacharya S R Tripathi C K Pradhan S K Kashyap 《Indian journal of experimental biology》1990,28(9):849-857
To examine the effects of heat and noise individually and jointly on certain physiological responses and cognitive and neuromotor based functions, 12 male participants were tested under 6 experimental conditions which resulted by combining 3 levels of heat (25 degrees, 30 degrees and 35 degrees C) and 2 levels of white noise (70 and 100 dB). The experiment was carried out in a controlled climatic chamber following two 6 x 6 latin square designs. The results indicated elevations in heart rate, oxygen uptake and body temperature due to the independent effect of heat or the combined effects of heat and noise. The independent action of noise was found to be depressive on the first two responses. On the neuropsychological effects, the heat adversely affected the speed in card sorting (by design configuration) and digit symbol tests, and also the accuracy and error rate in the reasoning ability test. The noise caused performance improvements in critical flicker frequency (simultaneous) and in error rates in card sorting (by design configuration). The combined effects of heat and noise indicated higher error rates in card sorting (by face value), decreased accuracy in reasoning ability and improvements in performance in accuracy scores and error rates in digit symbol test. 相似文献
37.
A Bhattacharya B K Vonderhaar 《Biochemical and biophysical research communications》1979,88(4):1405-1411
Membranes from mammary glands of mildly hypothyroid mice show a 70–85% reduction in prolactin binding while those from hyperthyroid mice bound 66% more prolactin compared to similar preparations from euthyroid animals. The prolactin binding data for mammary glands correlate well with the ability of the tissue from animals in various thyroid states to respond to prolactin with increased lactose synthetase activity. Binding of prolactin to mammary membranes is enhanced when explants from mid-pregnant mice are cultured overnight in the presence of insulin, hydrocortisone and 10?9 M L-T3. This enhancement is not blocked by puromycin. These data suggest that thyroid hormones control the level of prolactin binding in mouse mammary tissue. This may be accomplished, at least in part, by activation of preexisting receptor molecules. 相似文献
38.
39.
Exogenously supplied ribose and deoxyribose in a medium containingsucrose+ IAA considerably enhanced the formation of roots onhypocotyl cuttings of Phaseolus mungo with intact apex andleaves.The effect increased with increasing concentration of pentosesugars and was more pronounced with deoxyribose than with ribosesugar. (Received October 25, 1975; ) 相似文献
40.
Payal Singh Pradipta Bandyopadhyay Sudha Bhattacharya A Krishnamachari Supratim Sengupta 《BMC bioinformatics》2009,10(1):325