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111.
LAURE LECOIN PASCALE MERCIER NICOLE M. LE DOUARIN 《Pigment cell & melanoma research》1994,7(4):210-216
In the Silky Fowl (SF) breed of chicken, most of the internal organs are infiltrated with melanocytes. Previous studies have shown that this generalized mesodermal pigmentation is not due to a cell autonomous abnormality of the melanocytes but to environmental factors able to promote both the homing of pigment cell precursors in abnormal embryonic sites and their proliferation and differentiation. To analyse the mode of these environmental cues, we tested the effect of SF embryo extract (SFEE) on cultured quail neural crest cells as compared with that of EE from normal chickens of the JA57 strain (JA57EE). We found that SFEE enhances crest cell proliferation as judged by 3H-TdR incorporation and cell counting. In contrast, no effect of SFEE was observed either on the proportion of cultured cells that are engaged into the melanocytic differentiation pathway or on the amount of melanin produced by each differentiated pigment cell. The simple observation, however, reveals that SFEE has a significant effect on pigmentation of the cultured quail neural crest cells. This effect has therefore to be accounted for by the general increase in cell number induced by SFEE. The question is raised as to whether the in vivo SF phenotype is generated exclusively by this mechanism. 相似文献
112.
利用离体诱变技术选育小麦大粒种质的研究 总被引:3,自引:0,他引:3
以鲁麦12等为材料进行幼层培养,转分化前辐照1000rad,在R2代调查千粒重变异情况,结果表明,后代千粒重发生了显著变化,变异范围为39.5—68.5g.突变率高达63.08%,最高千粒重超过对照40.95%。已选出一批大粒材料应用于生产.其中核生二号新品种千粒重65g,杂交后代表明,大粒变异多为显性突变。 相似文献
113.
T. E. Tautorus M. M. Lulsdorf S. I. Kikcio D. I. Dunstan 《In vitro cellular & developmental biology. Plant》1994,30(1):58-63
Summary Embryogenic cell cultures ofPicea mariana (black spruce) and the species complexPicea glauca-engelmannii (interior spruce) were maintained either as suspensions in liquid medium in 250 or 500-ml-capacity shake-flasks, 7-liter-capacity
airlift or mechanically stirred bioreactors, or on agar-solidified medium. Cultures from each of the maintenance conditions
were subsequently transferred to agar-solidified LP medium containing 40μM (±) -abscisic acid for maturation into cotyledonary stage embryos. For both species, the highest maturation frequency resulted
from cultures grown in the airlift bioreactor. With black spruce cells grown in the airlift bioreactor containing LP medium
with 60 mM sucrose, a maximum of 7.1 g·liter−1 dry weight and 2892 embryos·ml−1 were obtained after 15 days. For interior spruce cells, a maximum dry weight of 5.9 g·liter−1 and 2698 embryos·ml−1 were obtained after 21 to 30 days. During culture over 2 wk, ammonia was almost completely utilized by both species, wherease
nitrate was depleted to 40% of the initial concentration. Sucrose was rapidly hydrolyzed to glucose and fructose by both species.
Black spruce cultures preferentially metabolized glucose, whereas interior spruce preferentially metabolized fructose. Improved
growth of interior spruce cells in mechanically stirred bioreactors occurred when cultured in LP medium with 60 mM fructose as the sole carbon source.
NRCC no. 36479 相似文献
114.
Summary Somatic embryos could be induced from the cotyledons of zygotic embryos from immature fruits ofFeijoa sellowiana Berg (Feijoa) in the presence of a wide range of concentrations of fructose, glucose, maltose, and sucrose. Mannitol or sorbitol
alone were ineffective. The highest frequencies of induction (99%) and the greatest number of somatic embryos per explant
(134) were obtained with 0.4M fructose and 0.3M sucrose, respectively. This sucrose concentration also showed greater induction capacity than equimolar combinations of its
monosaccharide constituents combined. Somatic embryo development was arrested at the globular stage at concentrations higher
than 0.5M of all the sugars tested. When transferred to solid germination medium containing 2.0 mg/liter (5.77μM) gibberellic acid, 0.5 mg/liter (2.32μM) kinetin, and 0.029M sucrose, somatic embryos formed under 0.3 or 0.4M sucrose had better germination capacity than those induced under lower (0.1 and 0.2M) concentrations, as assessed by the frequency of explants presenting germinated embryos and by the number of plants obtained
from those explants. On liquid media of similar composition somatic embryos did not germinate. Our data suggest that high
(0.3 to 0.4M) carbohydrate levels improve somatic embryogenesis by acting both as carbon source and as osmotic regulator. 相似文献
115.
Alginate-chitosan coacervation in production of artificial seeds 总被引:5,自引:0,他引:5
Survival of secondary embryoids of winter oilseed rape (Brassica napus ssp. oleifera cv. Primor) has been used as an assay for the development of artificial seeds involving complex coacervation of alginate (polyanion) with chitosan (polycation). Germination frequency of 100% was achieved for encapsulated embryoids when alginate formed the inner matrix and chitosan the outer layer. When the matrix makeup was reversed, there was no germination of embryoids. The artificial seeds produced were hardened in dilute alkaline solutions of NaOH and Ca(OH)(2). An optimum setting time could be selected based on a quantitative measurement of resistance of hardened capsules to compression and the germination frequency of the encapsulated embryoids. (c) 1993 John Wiley & Sons, Inc. 相似文献
116.
A novel method is described for the on-line determination of viable cell number. It has been tested in fermentations of Escherichia coli. The cells are transfected with the gene for firefly luciferase and fed low levels of luciferin in the medium. The reaction requires ATP, so the nonviable cells cannot produce light. Thus, light production is linear with viable cell density from innoculation through most of exponential growth. The light emitted by these cells is then conducted from the reaction vessel to the light detection equipment by an optical fiber. With the equipment described below, as few as a 10(6) cells/mL, or an OD(600) of 0.004, are easily detectable and concentrations greater than 10(10) cells/mL are well within range. The data are collected by a computer, so adaptation to on-line control applications is straightforward. During lag phase, this method is much more accurate then optical density measurements. At the end of exponential growth, rapid changes in light production mark carbon source depletion and the onset of cell lysis. A simple model accounts for the luciferin used during the fermentation and corrects the light detected to the proper cell density. (c) 1993 John Wiley & Sons, Inc. 相似文献
117.
A systematic survey for the presence of birefringent (anisotropic) structures in rotifers was undertaken. Several common features of rotifers exhibit anisotropism (e.g. trophi & muscles). However, unusual anisotropic crystalline structures (ACS) were found in late stage embryos (i.e. possessing eyespots and trophi, and showing movement). ACS were found in 18 of 26 species of monogonont rotifers (comprising 11 genera of 5 families). In Sinantherina socialis, ACS were present in the lower gut as compact, spherical masses of minute crystals that slowly broke apart and disappeared within 20 hours of hatching. Although several authors have described the existence of refractive bodies in rotifers, to my knowledge this is the first report of their birefringent properties. 相似文献
118.
Scott L. Nyberg Russell A. Shatford William D. Payne Wei-Shou Hu Frank B. Cerra 《Biotechnic & histochemistry》1993,68(1):56-63
To establish the importance of fluorescein diacetate (FDA) as a viability stain for cultured hepatocytes. we hypothesized that FDA staining would correlate positively with hepatocyte viability and function. Mixtures of live and dead cells were stained with FDA and scanned by flow cytometry. A close correlation was observed between the live cell fraction and percent viability as determined by FDA staining (R2 = 0.962). Hepatocytes were also sorted into low fluorescence and high fluorescence groups. Both albumin production and lidocaine metabolism (P-450 activity) were significantly increased in the high fluorescence group compared to the low fluorescence group. An automated, fluorescence-activated assay was useful for rapid assessment of hepatocyte viability. In addition. the intensity of green fluorescence following staining with FDA correlated well with two specific measures of hepatocyte function. 相似文献
119.
David I. Dunstan Terry D. Bethune Cheryl A. Bock 《In vitro cellular & developmental biology. Plant》1993,29(3):109-112
Summary The production of cotyledonary somatic embryos of white spruce from cultures grown long-term as suspensions was investigated.
We report the effects of removal of 2,4-dichlorophenoxyacetic acid (2,4-D) from the maintenance medium (ordinarily containing
both 2,4-D and benzyl adenine) before (±)-ABA-stimulated maturation. In particular the use of a 1-wk culture period
without 2,4-D was found to improve the production of normal-looking cotyledonary somatic embryos. Using high performance liquid
chromatography analyses of culture supernatants, it was determined that this affect was not related to altered ABA metabolism.
Germination of cotyledonary somatic embryos from cultures pretreated by the 1-wk culture period without 2,4-D was improved
compared with similar embryos from cultures that had not been pretreated. 相似文献
120.
Alberto C. Q. Pinto David H. Byrne Suzanne M. Dethier Rogers 《In vitro cellular & developmental biology. Plant》1993,29(2):55-58
Summary Ovule perforation technique and media components (plant growth regulators andl-glutamine) were tested on in vitro growth of immature (<3 mm) embryos of “Springcrest” and “Earligrande” peaches. Ovule perforation
was 2 to 4 times more effective in promoting embryo growth than leaving ovules intact.l-Glutamine (400 mg·liter−1) promoted an increase in growth but could not be used with indole-acetic acid plus kinetin because an antagonistic effect
on embryo growth occurred. The use of these exogenous plant growth regulators did not increase embryo growth over in vivo
growth. 相似文献