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991.
Sex ratio variations during brood development have important implications for the study of sex allocation in haplodiploid insects. So far, few studies have addressed this question because of the difficulty to determine the sex of the brood. We used flow cytometry to differentiate haploid males from diploid females in the ant Linepithema humile. Our data show that flow cytometry can be used successfully to distinguish between male and female brood on the basis of their DNA content, from the very first larval stage. Moreover, we show that flow cytometry allows sex brood determination in other ant species, as well as in nonsocial Hymenoptera. 相似文献
992.
Leone Tranqui Serge Soyez Marc R. Block 《In vitro cellular & developmental biology. Animal》1992,28(1):17-23
Summary A new approach was investigated to study the interaction between integrins and actin via intracytoplasmic proteins. Because
intracellular processes are hampered by the limiting plasma membrane, we developed an in vitro model with cells perforated
by a bacterial toxin, streptolysin O. The specific conditions for the use of permeabilized cells to study the intramolecular
associations occurring at adhesion plaques are described. The two cell types used, HUVEC and CHO, showed that the choice of
the perforation method is of great importance. After perforation of cells in a monolayer, 75±10% of the cells remained adherent
to a fibronectin substrate; after perforation of cells in suspension, only 25±10% of the cells readhered. Specific conditions
were required however to maintain these adhesive properties up to 4 h: the presence of 1 mM Mg++ in the medium was crucial, and it was necessary to layer the cells on a specific coat rather than a substitute such as gelatin.
Immunofluorescence investigations of actin, talin and vinculin, and Normarsky differential interference contrast microscopy
showed retention of focal adhesion plaques in perforated cells. Moreover, in perforated cells antibodies directed against
actin led to actin disorganization, showing that our model of perforated cells in a monolayer can give new insight to adhesion
study. 相似文献
993.
Anti-substance P anti-idiotypic antibodies. Characterization and biological activities 总被引:2,自引:0,他引:2
J Y Couraud E Escher D Regoli V Imhoff B Rossignol P Pradelles 《The Journal of biological chemistry》1985,260(16):9461-9469
Antibodies to substance P (SP) produced in rabbits have been characterized for their specificity toward SP and some 30 SP-related peptides. For each compound, we observed a close correlation between capacity of binding to anti-SP antibodies and biological activity, namely their spasmogenic effect on guinea pig ileum in vitro and their hypotensive effect in the rat in vivo, indicating that the combining sites of anti-SP and SP receptor(s) are structurally very similar. Further immunization of five rabbits with anti-SP immunoglobulins elicited in two allotype-matched animals the production of anti-SP anti-idiotypic antibodies. These latter antibodies were found to strongly inhibit the spasmogenic action of SP on the guinea pig ileum. In contrast, they specifically enhanced, like SP, phospholipid turnover in rat parotid gland cells, a physiological function mediated through an activation of SP receptors. Immunocytochemical studies actually revealed the presence of specific membranous binding sites for anti-idiotypic antibodies on the parotid gland-dissociated cells. The anti-idiotypic antibodies described here, which thus behave either as agonists or antagonists for SP depending on the biological test, might be used as original and powerful tools not only in studies of the receptor stereospecificity but also in attempts to purify the membranous SP receptors. 相似文献
994.
995.
Kamiel Spoelstra Serge Daan 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2008,194(3):235-242
Mutations in each of the genes mPer1, mPer2, mCry1 and mCry2 separately cause deviations from the wild type circadian system. Differences between these mutant strains have inspired the
hypothesis that the duality of circadian genes (two mPer and two mCry genes involved) is related to the existence of two components in the circadian oscillator (Daan et al., J Biol Rhythms 16:105–116,
2001). We tested the predictions from this theory that the circadian period (τ) lengthens under constant illumination (LL)
in mCry1 and mPer1 mutant mice, while it shortens in mCry2 and mPer2 mutants. mCry1
−/−
and mCry2
−/−
knockout mice both consistently increased τ with increasing light intensity, as did wild type mice. With increasing illumination,
rhythmicity is reduced in mCry1, mCry2 and mPer1, but not in mPer2 deficient mice. Results for mPer mutant mice are in agreement with data reported on these strains earlier by Steinlechner et al. (J Biol Rhythms 17:202–209,
2002), and also with the predictions from the model. The increase in cycle length of the circadian system by light in the
mCry2 deficient mice violates the predictions. The model is thereby rejected: the mCry genes do not play a differential role, although the opposite responses of mPer mutants to light remain consistent with a functional Evening–Morning differentiation. 相似文献
996.
997.
Ludovic Micallef Serge Battu Aline Pinon Jeanne Cook-Moreau Philippe J.P. Cardot Christiane Delage Alain Simon 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2010,878(15-16):1051-1058
The spontaneously immortalized human keratinocyte cell line HaCaT is widely used as a human keratinocyte model. In a previous comparative study between normal human keratinocytes (NHKs) and HaCaT, we reported that Ca2+ concentrations greater than 1 mM induced differentiation in vitro in both cell types, notably characterized by increased expression of differentiation markers keratins 1 (K1), 10 (K10) and involucrin. Surprisingly, cells had a higher proliferative activity than those cultured with low Ca2+ levels. These results raised many questions; in particular concerning the emergence of HaCaT cells subpopulation which would have different differentiation states and/or proliferation rates throughout Ca2+-induced differentiation. To isolate these subpopulations, we used sedimentation field-flow fractionation (SdFFF). Results demonstrated that the most differentiated cells (HC-F1), characterized by the highest expression of keratinocyte differentiation markers, had the lowest proliferative activity. In contrast, less differentiated cells (HC-F2) maintained a higher proliferative activity. SdFFF is a tool to sort differentiated and/or proliferating cells from a total pool previously treated with a Ca2+ concentration inducing differentiation, and can be use to prepare biological models necessary for studying HaCaT cell proliferation after Ca2+-induced differentiation treatment. 相似文献
998.
999.
Irina V. Budunova Leonid A. Mittleman Radjab D. Safaev Serge Yu. Fuchs Gennady A. Belitsky 《Cell biology and toxicology》1993,9(2):131-140
Benzo(e)pyrene (B(e)P) promotes carcinogenesis in the skin. Unlike some other promoters however, B(e)P does notproduce an uncoupling effect on gap junction permeability in DM15 transformedfibroblasts. This study demonstrates thatDM15 cells exhibit a relatively high level of B(e)P metabolism. Moreover, although pretreatment of DM15 cells with benz(a)anthracene results in an 8-fold increase of arylhydrocarbon hydroxylase activity and a 2-fold increase in the rate ofB(e)P metabolism, it did not enable B(e)P to affectLucifer Yellow transfer between DM15 cells. We conclude that neitherB(e)P nor its metabolites are capable of uncoupling gap junction permeability in DM15 cells.Abbreviations AHH
aryl hydrocarbon hyroxylase
- BA
benz(a)anthracene
- B(a)P
benzo(a)pyrene
- B(e)P
benzo(e)pyrene
- LY
Lucifer Yellow
- MFO
mixed-function oxidases
- PAH
polycyclic aromatic hydrocarbons 相似文献
1000.