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91.
K Kaneko J Milic-Emili M B Dolovich A Dawson D V Bates 《Journal of applied physiology》1966,21(3):767-777
92.
`Phosphatido-peptide'-like complexes formed by the interaction of calcium triphosphoinositide with protein 总被引:4,自引:0,他引:4 下载免费PDF全文
R. M. C. Dawson 《The Biochemical journal》1965,97(1):134-138
1. The sodium salt of triphosphoinositide partitions in the upper polar phase in a biphasic chloroform-methanol-water system similar to that of Folch et al. (1957). 2. On the addition of 2mug.atoms of Ca(2+) or Mg(2+) per mumole of triphosphoinositide the phospholipid passes entirely into the lower non-polar phase as the dicalcium or dimagnesium salt. 3. When serum albumin is included in the biphasic system, some of the dicalcium (dimagnesium) triphosphoinositide becomes attached to the protein material at the interface. 4. The affinity of Ca(2+) for triphosphoinositide is 2-2.5 times as great as that of Mg(2+) and the salt is not dissociated appreciably by equimolar amounts of EDTA or cyclohexane-1,2-diaminetetra-acetate. 5. When dicalcium triphosphoinositide is mixed with serum albumin a complex is formed which is insoluble in chloroform-methanol (2:1, v/v) but which dissolves completely when 0.25% (v/v) of concentrated hydrochloric acid is added. 6. On homogenizing a chloroform-methanol solution of dicalcium triphosphoinositide with guinea-pig liver the phospholipid becomes quantitatively attached to the insoluble residue, but it can be completely extracted from this with acidified chloroform-methanol. 7. The relevance of these observations to the significance of the phosphatido-peptide-complexes extracted from brain is discussed. 相似文献
93.
Jila H. Boal Scott F. Deamond Daniel E. Callahan Sarah A. Bruce Paul O. P. Ts'o L. L. Kan 《Cell biochemistry and biophysics》1989,14(3):245-256
The nuclear magnetic resonance (NMR) parameters, spin-lattice (T1), and spin-spin (T2) relaxation time, are usually longer for neoplastic cells than for normal cells of the same cell type. This has generally
been true at low NMR frequencies (≤100 MHz) when comparisons have been made between normal and neoplastic cells that have
both spent a short time in culture. We have previously demonstrated that although the T1 values of paired normal and neoplastic Syrian hamster (SH) fibroblastic cells in culture are not significantly different
when measured at 300 MHz, the 300 MHz T2 values for the neoplastic cells are smaller than those of the normal cells. (Xin et al. (1986),Cell Biophysics
8, 213.) Since treatment of normal diploid cells with polypeptide growth factors or tumor promoters frequently results in reversible
expression of neoplasia-associated phenotypes, T1 and T2 were obtained at 300 MHz for treated and untreated SH cells to see if these compounds could also produce smaller 300 MHz
T2 values. Secondary culture SH fetal fibroblast cells were treated with epidermal growth factor (EGF), fibroblast growth factor
(FGF), phorbol-12,13-didecanoate (PDD) and 4-α-phorbol-12,13-didecanoate (4αPDD). Treatment with either growth factor resulted
in smaller T2 values, but a statistically significant decrease was not observed for PDD or 4αPDD. The observed reductions in T2 values were correlated with the morphological and growth-stimulatory effects of these compounds on the cells. 相似文献
94.
J H Linehan C A Dawson R D Bongard T A Bronikowski D L Roerig 《Journal of applied physiology》1989,66(6):2617-2628
The influence of plasma albumin binding of the synthetic angiotensin-converting enzyme (ACE) substrate [3H]benzoyl-phenylalanyl-alanyl-proline (BPAP) on BPAP hydrolysis by pulmonary endothelial ACE was studied in isolated rabbit lungs perfused with a salt solution containing either 5% bovine serum albumin (BSA) or 5% dextran. The single-pass indicator-dilution method was used to measure the fraction (M) of [3H]BPAP hydrolyzed. Lung M was greater with albumin-free perfusate than when BSA was present. M decreased as the time (ti) that the BPAP was in contact with the BSA before reaching the lung was increased, suggesting that some BSA binding sites for BPAP were not in equilibrium during bolus transit through the lungs. The M vs. ti data were correlated using a model incorporating both rapid and slow binding kinetics of BPAP and BSA. For the slow BPAP-BSA interaction, the dissociation rate constant was approximately 0.015 s-1, and the fraction of the BPAP bound to these slowly equilibrating sites at equilibrium was approximately 22%. The results indicate that transient plasma protein binding kinetics can affect lung BPAP hydrolysis. 相似文献
95.
96.
97.
Damian F. J. Purcell Nicholas J. Deacon Sarah M. Andrew Ian F. C. McKenzie 《Immunogenetics》1990,31(1):21-28
CD46, until recently known as HuLy-m5, is a non-lineage restricted surface antigen ubiquitously expressed by almost all human cells except erythrocytes. The CD46 antigen is identified by the E4.3 monoclonal antibody (mAb) and exists at the surface of human peripheral blood lymphocytes (PBLs) as two acidic, non-disulfide bonded chains, and , ofM
r 66 000 and 56 000. Receptor density analysis showed that CD46 was of moderately low abundance on PBLs with 7.5×103 molecules present on each cell. The two chains of CD46 were purified (144 000-fold) by immunoaffinity-chromatography with E4.3 mAb from the plasma membranes of a human spleen infiltrated with chronic myelogenous leukemia cells. Amino acid sequence analysis of the NH2-terminal of both and chains yielded the same sequence; XEEPPQ/TFEAMELIGKPKPYYEIGE. Peptide mapping studies confirmed that both CD46 chains were closely related, except for one peptide fragment. This amino acid sequence is identical to that of the NH2-terminal of the recently cloned membrane co-factor protein (MCP), a membrane protein that binds the C3b and C4b fragments of complement and acts as a co-factor for I protein-mediated decay of the complement convertases. CD46 shares a cross-reactive epitope with some primate retroviruses, and this may indicate that some retroviruses mimic the mechanisms used by autologous human cells to evade complement-mediated immune clearance.
Offprint requests to: I. F. C. McKenzie. 相似文献
98.
Mutation analysis of the cystic fibrosis transmembrane regulator gene in native American populations of the southwest 下载免费PDF全文
Theresa A. Grebe Winifred W. Doane Sarah F. Richter Carol Clericuzio R. A. Norman William K. Seltzer Susan N. Rhodes Bruce E. Goldberg Lucy S. Hernried Melody McClure Gail Kaplan 《American journal of human genetics》1992,51(4):736-740
We report DNA and clinical analyses of cystic fibrosis (CF) in two previously unstudied, genetically isolated populations: Pueblo and Navajo Native Americans. Direct mutation analysis of six mutations of the CFTR gene--namely, delta F508, G542X, G551D, R553X, N1303K, and W1282X--was performed on PCR-amplified genomic DNA extracted from blood samples. Haplotype analyses with marker/enzyme pairs XV2c/TaqI and KM19/PstI were performed as well. Of the 12 affected individuals studied, no delta F508 mutation was detected; only one G542X mutation was found. None of the other mutations was detected. All affected individuals have either an AA, AC, or CC haplotype, except for the one carrying the G542X mutation, who has the haplotype AB. Clinically, six of the affected individuals examined exhibit growth deficiency, and five (all from the Zuni Pueblo) have a severe CF phenotype. Four of the six Zunis with CF are also microcephalic, a finding not previously noted in CF patients. Our DNA data have serious implications for risk assessment of CF carrier status for these people. 相似文献
99.
Sarah L. Roberts-Oehlschlager James M. Dunwell 《Plant Cell, Tissue and Organ Culture》1990,20(3):235-240
A period of four days preincubation at 25 °C on a medium containing mannitol was found to be superior to those pretreatments requiring incubation at 4 °C. In addition, the yield of green plants was improved by orienting anthers flat on the medium during mannitol preincubation, and reducing the number of anthers cultured per dish. 相似文献
100.
Toshimitsu Okeda Yasushi Yokogawa Hiroaki Ueo Mary A. Bury Paul O. P. Ts'o Sarah A. Bruce 《In vitro cellular & developmental biology. Plant》1990,26(12):1157-1166
Summary Primary cultures of 9-d-gestation Syrian hamster embryo (E9) cells are distinct from primary cultures of later gestational
age in terms of their growth and differentiation. First, primary E9 cell cultures express multiple mesenchymal differentiation
lineages (e.g., adipocyte, myoblast) only rarely seen in cultures of 13-d-gestation fetal (F13) cells. Second, although most
primary E9 cultures have a limited in vitro proliferative life span and exhibit cellular senescence similar to primary cultures
of F13 cells, E9 cultures seem to have higher frequency of escape from senescence and conversion to continuous cell lines
compared to F13 cells. Moreover, this frequency can be further increased 4- to 5-fold by continuous exposure of the E9 cells
to tumor promoters or epidermal growth factor. Eleven continuous cell lines have been isolated from unreated, promoter-treated,
or epidermal growth factor-treated primary E9 cultures. Seven of these are neoplastic or preneoplastic. However, the remaining
four do not show any evidence of being in neoplastic progression and three of these continue to express the same differentiated
phenotype observed in ther parental primary cell cultures.
These studies were supported in part by grants from the National Institutes of Health (AG 01998), Bethesda, MD, and the U.S.
Department of Energy (DE-A-C02-76-EVO-3280), Washington, DC. 相似文献