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51.
Morphology and lactose synthesis in tissue culture of mammary alveoli isolated from lactating mice 总被引:1,自引:0,他引:1
Polly R. Cline Paul O. Zamora Howard L. Hosick 《In vitro cellular & developmental biology. Plant》1982,18(8):694-702
Summary Mammary epithelial cells from lactating mice synthesize and secrete lactose in culture and retain many features of their in
vivo morphology if mammary glands are only partially dissociated to alveoli, rather than completely dissociated to single
cells. After 5 d in culture lactose synthesis by alveoli cultured on floating collagen gels is 10 to 20 times higher than
in cultures of single cells on floating collagen gels. Moreover, mammary alveoli in culture retain sensitivity to lactogenic
hormones; the synthesis of lactose by alveoli depends on the continued presence of insulin and either hydrocortisone or prolactin.
In addition, within alveoli the original juxtaposition of constituent epithelial cells is retained, and cells are cuboidal
and have many microvilli and fat droplets. In contrast, alveoli on attached gels flatten and lose their secretory morphology.
These results indicate that the shape of the cells, presence of lactogenic hormones, and maintenance of epithelial:epithelial
cell contacts are required for maintenance of mammary epithelial cell differentiation in culture.
This research was supported by Grants CA-16392 and AG-02909 from the National Institutes of Health and Institutional Grant
IN 119 from the American Cancer Society. 相似文献
52.
Summary The symbiotic heterocystous cyanobacteriumAnabaena azollae present in the leaf cavities of the water fernAzolla spp. was studied. The cyanobacteria extracted from the leaf cavities showed differences in pigment composition in three species ofAzolla, i.e A.pinnata var.pinnata, A.caroliniana and A.filiculoides, as observed by pigment absorption and epifluorescence tests. These differences suggest that of these species the cyanobiont ofA. pinnata is the most actively nitrogenfixing form. This has been confirmed by nitrogen fixation (acetylene reduction) tests. Heterocysts of the symbiont ofA. pinnata were characterized by high chlorophylla and low phycocyanin content, a low fluorescence yield of chlorophyll in the heterocysts compared to vegetative cells and a gradient of phycocyanin concentration in the vegetative cells adjacent to heterocysts. This indicates that only photosystem I is present in the heterocyst. In the two otherAzolla species quantitative shifts in the pigment composition occurred suggesting a lower nitrogen fixation activity.In the cyanobiontAnabaena azollae the heterocyst frequency could reach a value of 44–45%. It is argued that there are two generations of heterocysts in a matureAzolla plant, which are concomitant with two peaks of nitrogen fixation activity correlated with leaf age,i.e. leaf number along the main axis of the plant. At both peaks of maximal N2-ase activity, only 20–25% of the heterocysts present are metabolically active as demonstrated by the reduction of Neotetrazolium chloride (NTC) in the heterocysts and darkening of nuclear emulsions by silver salt reduction. Vegetative cells of the cyanobiont reduce Neotetrazolium chloride (NTC) to formazan more rapidly than has been observed in the free-living heterocystous cyanobacteriumAnabaena cylindrica tested in parallel experiments. This feature may be due to a more permeable cell wall of the vegetative cells of the cyanobiont compared to the free-living form, since the vegetative cells of the symbiont play a role in cross-feeding of the host (Azolla).Evidence is obtained that only the heterocysts of the cyanobiont ofAzolla are involved in the nitrogen fixation process as in free-living heterocystous cyanobacterium species. This situation is different from other cyanobacterial symbioses such as inGunnera, Blasia andAnthoceros, where physiological modifications are reported in the symbiosis with another photosynthetic partner such as the absence of O2 evolution and the absence of photo-fixation of CO2 in the cyanobionts.Pigment composition and N2-ase activity in the symbiotic cyanobacteria of three Azolla species have indicated the superiority of theA. pinnata symbiont.A. pinnata var.pinnata is a semidomesticated form used in S.E. Asia for agricultural purposes (irrigated rice culture) to increase soil fertility.It is suggested that by selection (domestication) more efficient strains (clones) can be obtained, and further that with more advanced techniques such as gene mutation and genetic manipulation even more efficient and for agriculture more beneficial clones can be obtained. 相似文献
53.
Lev Fishelson 《Environmental Biology of Fishes》1980,5(2):161-165
Synopsis The architecture of the gill structure of variousTilapia species was studied in relation to their adaptability to hypersaline media. Using SEM and EM, it was shown that the squamose
epithelial cells of the gills have species-typical patterns of ridges on their outer surfaces. These have previously been
misinterpreted by other authors as microvilli or stereocillia. The ridges are more dense and better developed in euryhaline
species, likeT. zillii, and less so in stenohaline species likeSarotherodon niloticus. Comparing freshwater and seawater-adapted individuals ofT. zillii, S. niloticus, S. galflaeus, andTristramella sacra, it was shown that in fresh water the surface cells are slightly swollen, extending over the openings of the chloride cells.
During adaptation to sea water, these ridges become higher and denser and the cell surface shrinks, exposing the underlying
orifices of the apical crypts of the chloride cells. The more euryhaline the species, the less change there is in the ridge
pattern of the cells during passage from fresh to sea water. This evidence implicates the gill epithelium, together with the
chloride cells, in the process of osmoregulation. 相似文献
54.
55.
J. D. Sobel R. Tchao J. Bozzola M. E. Levison D. Kaye 《In vitro cellular & developmental biology. Plant》1979,15(12):993-1000
Summary Fragments of normal human adult vagina, when explanted onto glass slides gave rise to outgrowing sheets of pure epithelium,
which had microscopic morphological features in common with normal vaginal epithelium. Infrequent fibroblast contamination
was observed. Proliferating epithelial cells formedmultilayers of stratified squamous epithelium and demonstrated a progressive decrease in proliferative activity after 14 days. Continuous
lines of epithelial cells were not obtained. Even in the absence of estrogens, transmission electron microscopy revealed evidence
of keratinization of the superficial cells of the multilayer. Scanning electron microscopy of the surface of mature epithelial
cells in culture revealed ultrastructural features that closely resembled those present on the surface of exfoliated cells
obtained by scraping the vagina in vivo. This in vitro tissue culture model of human vaginal epithelium may provide a simple
method of studying factors that influence vaginal epithelium growth, maturation and function. 相似文献
56.
Summary The nine-banded armadillo possesses a salivary bladder which is a dilated portion of the main duct of the submandibular gland at its origin. The wall of the bladder is composed of an epithelium, a submucosa and a thick coat of skeletal muscle. The ultrastructure of the epithelium reveals that it is complex and consists of three cell types: 1) principal cells, 2) light cells, and 3) basal cells. The general organization of the epithelium suggests that it is a transporting type of epithelium such as that found in the amphibian and reptilian urinary bladders and the mammalian gall bladder. The submucosa is composed primarily of densely-packed collagen fibers. The skeletal muscle is very vascular and richly innervated.This study was supported in part by a research grant from U.S.P.H.S. (GRS 5-S01-RR-05705)The authors wish to acknowledge the technical assistance of Elizabeth Underwood 相似文献
57.
Dr. H. A. R. Fritsch 《Cell and tissue research》1976,175(1):131-135
Summary Argyrophilic and argentaffin cells occur in the stomach and intestinal epithelium of the sea-squirt, Ciona intestinalis L.. These cells are characterized by their basal swelling which contains the nucleus surrounded by small secretory granules and by a filamentous cell-apex which reaches the gut lumen. The cells are scattered unevenly within the epithelium. Their number decreases rapidly towards the lower part of the intestine. The localization, size of granules and their shape are features which differentiate these cells from other secretory cells in the gut epithelium such as mucous cells. These cells are thought to possess an endocrine function.The excellent technical assistance of Mrs. R. Sprang is gratefully acknowledged 相似文献
58.
The caecal epithelium of Calicotyle kröyeri consists of a single cell type which functions in the uptake and intracellular digestion of host epidermis and associated mucus. Each cell is columnar with a small basal nucleus and prominent nucleolus. Perinuclear cytoplasm contains narrow profiles of GER and mitochondria with numerous cristae. Golgi complexes are small and indistinct. Most of the cell is filled with vacuoles of heterogeneous content, the largest occupying the cell apex. There is in each cell an apical endocytotic complex comprising cell surface lamellae, apical vesicles and numerous tubular invaginations of the plasmalemma. The limiting membrane of all these components is structurally modified and bears a highly organized array of peg-like structures on its luminal surface. The complex is capable of ingesting particulate food material from the gut lumen for transfer, via vesicles, to the vacuoles for digestion. Most of the vacuoles represent the digestive elements of the cell and, histochemically, are reactive for protein, mucus and carboxylic esterases. Indigestible residues and lipid droplets accumulate in the large apical vacuole and are periodically released to the lumen by exocytosis. Small, undifferentiated caecal cells were occasionally observed in the epithelium, but their development has not been recorded. 相似文献
59.
Dr. Rolf Dierichs 《Cell and tissue research》1975,160(3):399-410
Summary Scanning and transmission electron microscopy were used to study the inner architecture of the frog lung. In some specimens the alveolar surface mucus layer was removed to permit the examination of underlying features. The inner surface of the frog's lung is covered by a layer of microvilli belonging to only one type of epithelial cells. The boundaries of these epithelial cells are demarcated by small ridges. Different degrees of lung expansion cause variations of the surface topography. The morphology of certain surface features is examined in detail. Several methods of drying the specimens are compared.The author wishes to thank Dr. I. E. Richter, Institut für allgemeine und experimentelle Pathologie der Bundeswehr, Mainz, for the opportunity to do these investigations and for helpful discussions. 相似文献
60.
Gene delivery to respiratory epithelial cells by magnetofection 总被引:4,自引:0,他引:4
Gersting SW Schillinger U Lausier J Nicklaus P Rudolph C Plank C Reinhardt D Rosenecker J 《The journal of gene medicine》2004,6(8):913-922
BACKGROUND: For the topical application of DNA vector complexes to the airways, specific extracellular barriers play a major role. In particular, short contact time of complexes with the cell surface caused by the mucociliary clearance hinders cellular uptake of complexes. The aim of this study was to evaluate the ability of magnetofection, a technique based on the principle of magnetic drug targeting, to overcome these barriers in comparison with conventional nonviral gene transfer methods such as lipofection and polyfection. METHODS: Experiments were carried out on permanent (16HBE14o-) and primary airway epithelial cells (porcine and human), and native porcine airway epithelium ex vivo. Transfection efficiency and dose-response relationship of magnetofection were examined by luciferase reporter gene expression. Sedimentation patterns and uptake of gene transfer complexes were characterized by fluorescence and electron microscopy, respectively. RESULTS: We show that (i) application of a magnetic field allows the magnetofectins to sediment and to enrich at the cell surface within a few minutes, (ii) magnetofection bears an improved dose-response relationship, (iii) magnetofection enhances transfection efficiency in both, permanent and primary airway epithelial cells, and (iv) magnetofection leads to significant transgene expression at very short incubation times in an ex vivo airway epithelium organ model. CONCLUSIONS: Magnetofection provides a potential novel method, which may overcome fundamental limitations of nonviral gene transfer to the airways. Due to the accelerated enrichment at the cell surface it may be of major interest for in vivo applications, where long-term incubation times at the target tissue are hardly achievable. 相似文献