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91.
Martin J. Milner Alison J. Bleasby Andrew Pyott 《Development genes and evolution》1984,193(6):406-413
Summary The fusion of the eye-antennal discs during culturein vitro has been investigated, and the complex morphogenetic movements which occur during the formation of the head capsule of the insect are described. The initial contact between the eye anlagen is by means of cell processes spanning the gap between the two discs. Subsequently the two epithelia become firmly apposed, and then the integrity of the epithelium in the region of fusion breaks down, cells appearing to move to new positions in order to form an epithelium which unites the two discs. The epithelium eventually secretes a pattern of cuticular structures which is continuous between the derivatives of the two discs. Bristles on either side of the line of fusion are perfectly aligned, and structures such as the median ocellus, which are formed jointly by the cells of the two discs, differentiate normally. This is also found when left and right eye-antennal discs of different genotypes are placed side-by-side, indicating that processes of pattern regulation can occur in culture. 相似文献
92.
R. J. J. Kanoza D. M. Brunette A. D. Purdon J. Sodek 《In vitro cellular & developmental biology. Plant》1978,14(9):746-753
Summary An operational criterion for the identification and isolation of epithelial-like (E) cells, based on their ability to cover
and protect, a collagen gel from the action of collagenase, has been developed. The E cells isolated by this collagenase-separation
technique (CST) exhibited the ultrastructural features, including desmosomes and abundant tonofilaments, that are considered
characteristic of this cell type. Unlike confluent cultures of fibroblast-like (F) cells, E cells were not found to have large
external transformation-sensitive (LETS) protein on their surface membranes. The CST provides a nondestructive, and efficient
means of identifying and isolating E cells from mixed populations. 相似文献
93.
A new cell culture microcarrier that can be covalently bonded by cell attachment proteins and can be thin-sectioned for electron microscopy was synthesized. It was easily made by sulfonating cross-linked polystyrene beads for a negative surface charge followed by covalent attachment of polyethylenimine for a positive charge. Cell attachment proteins, e.g. collagen, was covalently bonded directly to the microcarrier using a carbodiimide or after activating the microcarrier surface with glutaraldehyde. HeLa-S3 cells attached, spread and grew to confluence more efficiently on the positive microcarriers and those coated with collagen than on the negative ones. Endothelial cells grew best on those with a negative surface charge. The nature of the microcarrier surface was not the only aspect involved in cell adhesion but also the type of serum proteins adsorbed. Qualitatively different proteins coated the microcarriers depending upon whether the carrier was negative, positive or coated with collagen. Comparison of various types of available microcarriers indicated that the modified cross-linked polystyrene beads used here were best for transmission and scanning electron microscopy. Endothelial cells grown on the microcarriers had the same ultrastructure as cells grown in monolayers in culture dishes. Of a variety of microcarriers tested the modified cross-linked polystyrene beads were the only ones that could be used for both ultrastructural and biochemical techniques. 相似文献
94.
Reversion of Texas male-sterile cytoplasm maize in culture to give fertile,T-toxin resistant plants 总被引:5,自引:0,他引:5
R. I. S. Brettell Dr. E. Thomas D. S. Ingram 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1980,57(4):55-58
Summary Plants carrying Texas male-sterile (Tms) cytoplasm are normally sensitive to Drechslera maydis T-toxin. Tissue cultures were initiated from immature embryos of maize carrying Tms-cytoplasm, and plants were regenerated after selection for resistance to T-toxin. Fertile, T-toxin resistant plants were obtained from the unselected control cultures as well as from the selected material. In addition, one regenerant from an unselected culture was fertile and T-toxin sensitive. The progeny of the regenerants showed the phenotype of the female parent with respect to pollen-fertility, and T-toxin resistance. The data are consistent with the heritable changes observed being the result of the expression of an altered mitochondrial genome. 相似文献
95.
A DNA polymerase activity was isolated from cells of Oryza sativa L. grown in suspension culture. Molecular mass ( 180,000), optimal requirements for pH (neutral), Mg2+ (5–10 mM), Mn2+ (1 mM), template preference (activated DNA), lack of activity with native or denatured DNA, and sensitivity to N-ethylmaleimide and ionic strength are similar to those of the vertebrate -polymerase. Like DNA polymerase , the DNA polymerase described in this work is the most abundant in proliferating cells of Oryza sativa L., Parthenocissus tricuspidata (Siebold et Zucc.) Planchon, Acer pseudoplatanus L., and Medicago sativa L. and responds to changes in the rate of cell multiplication. We therefore postulate that this -like DNA polymerase is the replicating enzyme of plant cells.Abbreviations BSA
bovine serum albumin
- EDTA
ethylendiamino-tetracetic acid
- DTT
dithiothreitol
- PTSF
p-toluenesulfonyl fluoride 相似文献
96.
William R. Tolbert Joseph Peder Richard C. Kimes 《In vitro cellular & developmental biology. Plant》1981,17(10):885-890
Summary A system has been developed for growth and maintenance of mammalian cells in suspension culture at high density. In principle,
the maintenance of constant levels of required nutrients coupled with the removal of toxic cell byproducts can support much
higher suspension cell densities than may be obtained in conventional spinners. The system consisted of 4- or 40-liter reaction
vessels equipped with a vertically supported rotating cylindrical filter. Agitation was provided by the magnetically driven,
rotating filter. Fresh medium was supplied at a rate of 10 to 20 ml/h per 109 cells and the expended medium free of cells was withdrawn through the rotating filter. Both pH and dissolved O2 and CO2 were monitored and regulated. Walker 256 carcinosarcoma cells have been grown in these reactors to densities 10-to 30-fold
greater than that obtained in Bellco spinners. In addition to high cell densities, the yield of cells per liter of medium
used was 2- to 3-fold that obtained in the conventional systems. Both 4-and 40-liter versions of this reactor have been operated
without the use of antibiotics. The 40-liter reactor also has been modified for chemostat operation. In a single run, for
example, the Walker cell density was maintained between 6 and 10×106 cells/ml with a total yield of 8.7×1011 cells from 360 liters of medium. 相似文献
97.
P/2e ratios were calculated from anaerobic chemostat cultures of Paracoccus denitrificans with nitrogenous oxides as electron acceptor. P/2e ratios were calculated, using the Y
ATP
max
values determined for aerobic cultures. When succinate was the carbon and energy source the average P/2e values of the sulphate-and succinate-limited cultures with nitrate as electron acceptor were 0.5 and 0.7, respectively, and of the nitrite-limited culture 0.9. With gluconate as carbon and energy source the average P/2e values of the gluconate-limited with nitrate as electron acceptor and nitrate limited cultures were 0.9 and 1.1, respectively.H+/O ratios measured in cells obtained from sulphate-, succinate, nitrite-, gluconate-and nitratelimited cultures yielded respective average values of 3.4, 4.5, 3.5, 4.8 and 6.2 for endogenous substrates. From our data we conclude that sulphate-and nitritelimitation causes the loss of site I phosphorylation. Nitrite has no influence on the maximum growth yield on ATP. We propose that metabolism in heterotrophically grown cells of Paracoccus dentrificans is regulated on the level of phosphorylation in the site I region of the electron transport chain. 相似文献
98.
Rangil Singh Consuelo M. Perez Cynthia G. Pascual Bienvenido O. Juliano 《Phytochemistry》1978,17(11):1869-1874
Five rices (Oryza sativa L.) differing in final grain size were studied at the midmilky stage to determine if any factor could be identified which might limit rate of starch accumulation. Only UDP glucose pyrophosphorylase activity increased with increasing grain size. Detached rice panicles incubated in liquid medium containing 1% sucrose and 0.1% glutamine, in addition to minerals and vitamins, produced grains similar to those on intact plants. Sucrose level (0–1.5%) in the medium determined the extent of dry matter and starch accumulation and influenced physiological development of the ripening grains. Chemical and enzymic composition of the grain were similar to previously reported levels in grains of intact panicles analysed at regular intervals after anthesis. Addition of 3-P glycerate or K+ to the medium did not improve dry matter accumulation in the developing grain. 相似文献
99.
G. W. Schaeffer 《In vitro cellular & developmental biology. Plant》1977,13(1):31-35
Summary This report describes the culture of Su/Su, Su/su and su/su tissue in vitro. High levels of auxin and low levels of cytokinin
increase growth of the cells. The cells do not need exogenous amino acids for rapid growth and the chlorophyll deficiency
cannot be overcome by amino acids. Reduced levels of auxin and sucrose enhance differentiation, whereas cysteine in the autoclaved
medium inhibit differentiation. The Su chlorophyll mutant of tobacco provides a marker for in vitro studies on photosynthesis
and photorespiration, chloroplast genetics and cell fusion techniques. 相似文献
100.