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901.
Summary Procedures have been developed for the initiation and long-term maintenance of embryogenic suspension cultures of pickling
cucumber (Cucumis sativus) cultivar Endeavor and for the regeneration of normal plantlets. Embryogenic calluses from petiole explants plated on Murashige
and Skoog (MS) medium with 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzylaminopurine (BA), both at 5μM, were used to initiate the embryogenic suspension cultures. Among various growth regulator combinations evaluated for initiation
and maintenance of these suspension cultures, only MS medium with 2,4-D and BA, both at 1μM, produced cultures that were yellow, friable, and still regenerable after repeated subculture (every two wk) over a 3- to
15-mo. period. The effects of various concentrations of auxin and cytokinin in the plating medium, the addition of AgNO3, and various plating procedures were also evaluated. The highest frequency of regeneration of shoots and plantlets was achieved
by plating aggregates onto filter paper overlaid on MS medium with naphthalene acetic acid (NAA)/BA at a concentration of
2:1 or 1:1μM. The addition of activated charcoal (0.5%) or AgNO3 (30μM) in the plating medium did not enhance the frequency of plantlet regeneration. The highest frequency of normal-appearing
plantlets recovered was 42 to 46% per petri dish. The procedures described in this study can be used to increase plantlet
recovery from individual embryogenic calluses of pickling cucumber. 相似文献
902.
S. Wright-Perkins M. R. Daniel C. Walker 《In vitro cellular & developmental biology. Animal》1994,30(7):450-459
Summary This study investigates the characteristics of two human cell lines—1PT and 1PT VARIANT A—both derived from the same histologically
undifferentiated, neuroendocrine positive, non-small cell lung carcinoma (NSCLC) and capable of growth in unsupplemented serum-free
minimum essential medium. In stationary culture, the cells of both lines grew both attached to a plastic substratum and in
suspension; the 1PT VARIANT A line formed three-dimensional clusters of loosely adherent cells. The cell lines differed in
their DNA content, the 1PT having 1.44 times and the 1PT VARIANT A having 2.39 times the normal human diploid DNA content.
Chromosome counts supported this observation, the ploidy of the 1PT and VARIANT A lines being 1.11 and 1.64, respectively.
On transmission electron microscopy the cells of both lines had dense core granules and immature desmosomes, whereas only
the 1PT VARIANT A line had mucin granules. Both lines formed, in nude mice, tumors that, like the original tumor from which
they were derived, were histologically undifferentiated and showed local invasion. The original tumor and both lines had demonstrable
neuroendocrine markers. Cytokeratins were apparent in the tumor but not the cell lines, and neurofilaments were present in
the cell lines only. Staining for epithelial membrane antigen, neural cell adhesion molecule, and desmoplakin differentiated
between the two lines. These lines provide a useful model for the investigation of the biology of the neuroendocrine positive
subgroup of NSCLC, which is clinically important because of the possible responsiveness of these tumors to chemotherapy. 相似文献
903.
Yoshiko Myoken Yoshinari Myoken Tetsuji Okamoto Mikio Kan J. Denry Sato Kazuaki Takada 《In vitro cellular & developmental biology. Animal》1994,30(11):790-795
Summary A squamous cell carcinoma cell line Nakata proliferated in serum-free culture and was not responsive to exogenous fibroblast
growth factor-1 (FGF-1). Immunostaining revealed that Nakata cells expressed FGF-1 in their cytoplasms and nuclei. Two molecular
mass species of FGF-1 (16 and 18 kDa) were identified in cell extracts by Western blot. These cells also expressed high-affinity
FGF-1 binding sites (Kd=360 pM, 28 000 sites/cell). The results of cross-linking with [125I]FGF-1 demonstrated the presence of two bands with molecular masses of 160 and 140 kDa. The addition of FGF-1 specific antisense
oligonucleotides at 25 μM to Nakata cells resulted in an 82% inhibition in cell growth and suppressed FGF-1 expression. This effect was dose-dependent
and specific, because sense oligonucleotides were ineffective in inhibiting cell growth. In addition, Nakata cell growth was
suppressed by an anti-FGF-1 neutralizing antibody, which resulted in a 52% inhibition at 8 μg/ml. These results demonstrate
that Nakata cells produce FGF-1, and indicate that this growth factor acts in an autocrine manner by interacting with FGF-1
binding sites on Nakata cells. 相似文献
904.
Kumiko Ui Shoko Nishihara M. Sakuma S. Togashi R. Ueda Y. Miyata T. Miyake 《In vitro cellular & developmental biology. Animal》1994,30(4):209-216
Summary From the central nervous system ofDrosophila melanogaster 3rd instar larvae, eight continuous cell lines have been established (named ML-DmBG1 to 8). Using ML-DmBG2, single colony
isolation was carried out and six colonial clones were obtained. All reacted to the antibody to horseradish peroxidase, which
is a neuronal marker in insects. Acetylcholine, a known neurotransmitter inDrosophila, was detected in three of the colonial clones by high performance liquid chromatography. Therefore, it is concluded that
the established colonial clones are neural cells originating in the larval central nervous system. Among them, some variation
was observed with respect to morphology, acetylcholine content, and reactivity to anti-HRP. The variation may reflect the
heterogeneity of cells composing the central nervous system. 相似文献
905.
Stephen D. Bird Robert J. Walker Michael J. Hubbard 《In vitro cellular & developmental biology. Animal》1994,30(7):420-424
Summary The effect of a conventional antibiotic (penicillin/streptomycin) mixture on the widely used kidney epithelial cell line,
LLC-PK1, was investigated by measuring growth and intracellular free calcium. Free calcium concentration was the same in cells cultured
for 3 to 7 wk with (“plus”) and without (“minus”) antibiotics both at rest and when challenged with high (14 mM) external calcium. When exposed to vasopressin, minus cells exhibited significantly smaller calcium transients than plus
cells. A similar difference existed for transients elicited by a calcium ionophore, 4-br-A23187. After longer periods of culture
(>20 wk), minus cells grew slower than plus cells but on reaching confluence (minus cells took 1 day longer) the morphologies
and viabilities were indistinguishable. The finding that culture with penicillin/streptomycin reversibly modified some properties
of LLC-PK1 cells, at least partly through altered calcium homeostasis, is of importance for workers using this cell model to study drug
effects and raises the general possibility of similar effects on other cultured cells. 相似文献
906.
P. J. Hatt M. Moriniere H. Oberlander P. Porcheron 《In vitro cellular & developmental biology. Animal》1994,30(10):717-720
Summary During postembryonic development of insects, molting cycles affect epidermal cells with alternate periods of proliferation
and differentiation. Cells of the cell line established from imaginal discs of the Indian meal moth (IAL-PID2) differentiate
under the action of the molting hormone, 20-hydroxyecdysone, in a manner that is meaningful in terms of the development of
the tissue from which they were derived. In particular, the hormone caused an accumulation of the cells in the G2 phase of
their cycle and induced the formation of epithelial-like aggregates and the synthesis of specific proteoglycans. Recent discovery
of members of the insulin superfamily in insects and the role of growth factors played by this family of molecules in vertebrates
led us to check for their potential effects on IAL-PID2 cell cycle regulation. On the one hand, our results showed that insulin
was involved in partial resumption of the cell cycle after an arrest caused by serum deprivation, but that other growth factors
present in fetal calf serum were needed for full completion of mitosis. On the other hand, the cytostatic effect of 20-hydroxyecdysone
was reversible, and, prior exposure of the cells to the hormone allowed the cells to complete one cell cycle in serum-free
medium. These results suggest that the production of autocrine growth factors induced by ecdysteroids could circumvent the
absence of serum. This cell culture model provides potential for further study of interactions between ecdysteroids and growth
factor homologs during differentiation of insect epidermal cells. 相似文献
907.
908.
909.
Bo Skaaning Jensen Flemming Jessen Else K. Hoffmann 《The Journal of membrane biology》1993,131(3):161-178
Summary Net Cl– uptake as well as unidirectional36Cl influx during regulatory volume increase (RVI) require external K+. Half-maximal rate of bumetanide-sensitive36Cl uptake is attained at about 3.3mm external K+. The bumetanide-sensitive K+ influx found during RVI is strongly dependent on both Na+ and Cl–. The bumetanide-sensitive unidirectional Na+ influx during RVI is dependent on K+ as well as on Cl–. The cotransporter activated during RVI in Ehrlich cells, therefore, seems to transport Na+, K+ and Cl–. In the presence of ouabain and Ba+ the stoichiometry of the bumetanide-sensitive net fluxes can be measured at 1.0 Na+, 0.8 K+, 2.0 Cl– or approximately 1 : Na, 1 : K, 2 : Cl. Under these circumstances the K+ and Cl– flux ratios (influx/efflux) for the bumetanide-sensitive component were estimated at 1.34 ±0.08 and 1.82 ± 0.15 which should be compared to the gradient for the Na+, K+, 2Cl– cotransport system at 1.75 ± 0.24.Addition of sucrose to hypertonicity causes the Ehrlich cells to shrink with no signs of RVI, whereas shrinkage with hypertonic standard medium (all extracellular ion concentrations increased) results in a RVI response towards the original cell volume. Under both conditions a bumetanide-sensitive unidirectional K+ influx is activated. During hypotonic conditions a small bumetanide-sensitive K+ influx is observed, indicating that the cotransport system is already activated.The cotransport is activated 10–15 fold by bradykinin, an agonist which stimulates phospholipase C resulting in release of internal Ca2+ and activation of protein kinase C.The anti-calmodulin drug pimozide inhibits most of the bumetanide-sensitive K+ influx during RVI. The cotransporter can be activated by the phorbol ester TPA. These results indicate that the stimulation of the Na+, K+, Cl– cotransport involves both Ca2+/calmodulin and protein kinase C. 相似文献
910.
Jacob Barg† Mariana Mancheva Belcheva Jan Rowiski Carmine James Coscia 《Journal of neurochemistry》1993,60(4):1505-1511
Abstract: A body of evidence has indicated that μ-opioid agonists can inhibit DNA synthesis in developing brain. We now report that K -selective opioid agonists (U69593 and U50488) modulate [3 H]thymidine incorporation into DNA in fetal rat brain cell aggregates in a dose- and developmental stage-dependent manner. K agonists decreased thymidine incorporation by 35% in cultures grown for 7 days, and this process was reversed by the K -selective antagonist, norbinaltorphimine, whereas in 21-day brain cell aggregates a 3,5-fold increase was evident. Cell labeling by [3 H]thymidine was also inhibited by the K -opioid agonist as shown by autoradiography. In addition, U69593 reduced basal rates of phosphoinositide formation in 7-day cultures and elevated it in 21-day cultures. Control levels were restored by norbin-altorphimine. Pertussis toxin blocked U69593-mediated inhibition of DNA synthesis. The action of K agonists on thymidine incorporation in the presence of chelerythrine, a protein kinase C (PKC) inhibitor, or in combination with LiCl, a noncompetitive inhibitor of inositol phosphatase, was attenuated in both 7- and 21-day cultures. These results suggest that K agonists may inhibit DNA synthesis via the phosphoinositide system with a pertussis toxin-sensitive G protein as transducer. In mixed glial cell aggregates, U50488 increased thymidine incorporation into DNA 3.1-fold, and this stimulation was reversed by the opioid antagonist naltrexone. 相似文献