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231.
Physiological and biochemical events leading to vitrification of plants cultured in vitro 总被引:12,自引:0,他引:12
Water content, peroxidase activity and isoperoxidases, phenylalanine ammonia-lyase activity and phenolic content were comparatively analyzed in tissues of normal and vitreous plants cultured in vitro. The release of ethylene in flask atmospheres by normal and vitrifying plants was also measured. On the basis of the results, it is hypothesized that vitrification results from a burst of ethylene controlled by the peroxidase-IAA-oxidase system. An initiating stress (e.g. excess of cytokinins or of NH4 + ions) would mediate the enhancement of the activity of soluble and membrane-bound peroxidases through a rapid modification of the phenolic level. The excess of ethylene in the atmosphere of stressed plants would retroinhibit its own biosynthesis and as a consequence decrease the activities of PAL and acidic peroxidases, thus hindering lignification processes. A parallel decrease in cellulose synthesis due to a diverted conversion of sugars to amino acids is expected (from data in the literature). Deficiency of both cellulose and lignin would allow more water uptake due to reduced wall pressure and bring about the hyperhydric malformations. 相似文献
232.
M. J. Babiano J. J. Aldasoro J. Hernández-Nistal D. Rodriguez A. Matilla G. Nicolás 《Physiologia plantarum》1984,61(3):391-395
Nonanoic acid, which inhibits germination in several seeds, enhanced ion efflux from embryonic axes of Cicer arietinum L., especially at temperatures above 25°C. Other short chain fatty acids had little effect on germination and ion leakage. Nonanoic acid also decreased uptake of 86 Rb+ and 22 Na+ and increased efflux of both isotopes from the embryonic axes into the incubation solution. Fusicoccin, which stimulates early germination in C. arietinum , counteracted the effects of nonanoic acid at both 25 and 30°C. These results suggest that nonanoic acid affects the integrity of plasmalemma and other membrane systems. Nonanoic acid thus inhibits cell elongation during early germination by disturbing ion exchange and inhibiting water uptake. 相似文献
233.
F González Echeverría P S Cuasnicú A Piazza L Pi?eiro J A Blaquier 《Journal of reproduction and fertility》1984,71(2):433-437
The fertility of spermatozoa from the different epididymal segments of hamsters was tested by in-vivo insemination. Caput and proximal corpus spermatozoa were non-fertile; spermatozoa from the distal corpus epididymidis fertilized 13% (38/290) oocytes and those from the proximal and distal cauda epididymidis 71 and 87%, respectively. When tested by in-vitro insemination, distal corpus spermatozoa penetrated 44% of oocytes while those from the distal cauda fertilized 87% of oocytes. Spermatozoa from the distal corpus recovered in Medium BMOC fertilized 13% (28/219) of oocytes in vivo, while those mixed with an epididymal protein preparation (0.8 mg protein/ml) fertilized 24% (49/204; P less than 0.01) of oocytes. When distal corpus spermatozoa were inseminated in vivo with 0.8 mg epididymal protein preparation 34% (31/90) oocytes were fertilized and only 22% (23/103; P less than 0.05) oocytes were fertilized when the proteins were obtained from epididymides of animals castrated for 30 days. When distal corpus spermatozoa were preincubated for 5 h in medium without (control) or with protein preparation (0.8 or 1.6 mg protein/ml), a significant increase in in-vitro oocyte penetration was found (25 compared with 45%; P less than 0.05) when the protein was present at 1.6 mg/ml. These results confirm and extend previous observations suggesting a role for androgen-dependent glycoproteins secreted by the epididymis in the acquisition of fertilizing ability that occurs during sperm maturation. 相似文献
234.
Nicole Crozet D. Huneau Vronique Desmedt Marie-Claire Thron D. Szllsi Suzanne Torrs Claude Svellec 《Molecular reproduction and development》1987,16(2):159-170
Ovine tubal (n = 87) and ovarian in vitro matured oocytes (n = 99) were fertilized in vitro with ejaculated spermatozoa capacitated for 8 h in modified defined medium buffered with Hepes. High levels of fertilization were obtained as assessed by development to two-to six-cell stage within 40 h (75. 8% for ovulated and 62. 6% for in vitro matured oocytes). Electron microscope analysis of oocytes 20–22 h after insemination indicated that in vitro fertilization approximated the in vivo events. Embryos (two- to six-cell) were transferred surgically to the oviducts of pseudopregnant rabbits. Three days later, 42 (from ovulated oocytes) and 15 (from in vitro matured oocytes) embryos were recovered; 26 (61. 9%) and 10 (66. 6%), respectively, had cleaved at least once. Embryos incubated in vivo (n = 20 from ovulated oocytes; n = 9 from in vitro matured oocytes) were transferred surgically to the uteri of seven and four recipient ewes resulting in four and two pregnancies, respectively, from which three and one, respectively, have been maintained ( > 3 months). The first lamb resulting from the in vitro fertilization of an ovulated oocyte was born. In addition, six embryos (two- to four-cell) from tubal oocytes and ten embryos (two- to six-cell) from in vitro matured oocytes were directly transferred to the oviducts of two and three ewes, respectively. Two pregnancies resulting from in vitro matured fertilized oocytes are in progress ( > 3 months). 相似文献
235.
236.
237.
Study of elastase-type activity in blister fluids of recessive dystrophic epidermolysis bullosa 总被引:1,自引:0,他引:1
Recessive dystrophic epidermolysis bullosa (RDEB) is characterized clinically by blister formation due to minor trauma and ultrastructurally by a progressive disappearance of anchoring fibrils at the dermoepidermal junction and of the oxytalan-type fibers which belong to the elastic fiber system. In this study, we determined the elastase-type activity in blister fluid obtained from 8 patients suffering from RDEB as compared to the suction fluid of experimental blisters in a healthy person and to the blister fluid of a patient suffering from epidermolysis bullosa simplex. One patient with dominant dystrophic epidermolysis of the albopapuloid type was also studied. Seven of the eight children with RDEB showed highly elevated values. The eighth child, treated with etretinate, as well as the patient suffering from dominant epidermolysis bullosa had moderately increased values. The determination of elastase-type activity in the blister fluid could therefore be useful to establish the differential diagnosis of recessive dystrophic epidermolysis bullosa. 相似文献
238.
239.
Gabriella Fóris MD PhD George A. Medgyesi Mátyás Hauck 《Molecular and cellular biochemistry》1986,69(2):127-137
Summary Met-enkephalin (ME) exerts a bimodal effect on functional activities of rat peritoneal macrophages (PM); in a range of low concentration (10-9-10-7 M) antibody dependent cellular cytotoxicity (ADCC)was markedly stimulated with a simultaneous decrease of Fc receptor (FcR) mediated phagocytosis while the opposite was observed at 10-6-10-5 M concentrations.Studying the possible underlying mechanism(s) the followings were recorded: (1) ME in all applied concentrations induced an early Na+ influx which was followed by a Ca2+ efflux in the range of low concentrations. In the range of high concentrations Na+ influx was accompanied by a Ca2+ influx. (2) ME at 10-8 M concentration induced a rise in cGMP level with a plateau in the 60–120th min of incubation. This effect was prevented by 10-5 M of naloxone. At 10-6 M concentration a transient rise of cAMP level was recorded which was not affected by naloxone. (3) Verapamil in 10-6 M abolished both the Ca2+ influx and the rise in cAMP level induced by 10-6-10-5 M ME but not the rise in cGMP level induced by lower ME concentrations. (4) cAMP elevation by high ME concentrations was abolished by enkephalinase inhibitory puromycin. (5) PM-enkephalinase as assessed by the cleavage of fluorogenic substrate L-alanine beta naphthylamide (ABNA), was inhibited by 10-6-10-5 M of ME. This inhibition was abolished by verapamil, but not affected by naloxone. In the range of low concentrations ME appears to act on specific delta opioid receptors and its action is positively coupled to guanylate cyclase. In relatively higher concentrations ME-action is not mediated by specific delta opioid receptors and it appears to involve Ca2+ influx, adenylate cyclase activation as well as the processing of hormone by PM-enkephalinase. 相似文献
240.
Ethanol-sensitive mutants of Saccharomyces cerevisiae 总被引:3,自引:0,他引:3
Saccharomyces cerevisiae mutants unable to grow at ethanol concentrations at which the wild type strain S288C does grow, have been isolated. Some of them show additional phenotypic alterations in colony size, temperature sensitivity and viability in ethanol, which cosegregate with the growth sensitivity in ethanol. 21 selected monogenic ethanol-sensitive mutants define 20 complementation groups, denominated ETA1 to ETA20, which indicates that there is a high number of genes involved in the ethanol tolerance/sensitivity mechanism.Out of 21 selected monogenic mutants, 20 are not altered in the glycolytic pathway since, when maintained in glucosesupplemented medium, they can produce as much ethanol as the wild type and at about the same velocity. Nor do any of the mutants seem to be altered in the lipid biosynthetic pathway since, whether grown in the absence or in the presence of ethanol, their concentration of fatty acids and ergosterol is similar to that of the wild type under the same conditions. Therefore growth sensitivity to ethanol does not seem necessarily to be related to carbohydrate or lipid metabolism.Non-common abbreviations YP
yeast extract peptone medium
- YPD
yeast extract peptone dextrose agar or medium
- YPG
yeast extract peptone glycerol agar
- YPDE
yeast extract peptone dextrose ethanol agar or medium
- SD
yeast nitrogen base dextrose agar
- SPO
yeast extract potassium acetate glucose agar
- PD
parental ditype
- NPD
non-parental ditype
- TT
tetratype 相似文献