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Molecular analysis of de novo germline mutations in the von Hippel-Lindau disease gene 总被引:4,自引:0,他引:4
Richards Frances M.; Payne Stewart J.; Zbar Berton; Affara Nabeel A.; Ferguson-Smith Malcolm A.; Maher Eamonn R. 《Human molecular genetics》1995,4(11):2139-2143
VHL disease is a dominantly inherited familial cancer syndromewith variable expression and age-dependent penetrance. The diagnosisof isolated cases is often delayed compared with familial cases,and estimates of the new mutation rate have varied more than20-fold. To investigate the frequency and origin of de novoVHL gene mutations we have analysed: (i) families with identicalmutations to determine if there is a common haplotype, and (ii)apparent new mutation cases to determine whether the clinicaldiagnosis of such cases is reliable and to define the parentalorigin of de novo VHL gene mutations. Haplotyping of 12 VHLmutations occurring in two or more families (total 42 kindreds)revealed that for most mutations there was no evidence of afounder effect. A marked bias for a paternal origin of new mutationshas been reported in other familial cancer syndromes such asneurofibromatosis type 1 (NF1), multiple endocrine neoplasia(MEN) 2B and bilateral retinoblastoma, but it is unclear whetherthis bias results from a greater susceptibility for mutagenesisduring male gametogenesis because of the larger number of celldivisions compared with that in oogenesis, or from genomic imprintingeffects. Analysis of 13 de novo VHL mutations in which the parentof origin could be established, showed no evidence for a biasfor a paternal origin (seven paternal, six maternal), and differedsignificantly from that reported in NF1, MEN2B and bilateralretinoblastoma. This result demonstrates that an increased susceptibilityto paternal allele mutation is not a universal finding in autosomalgenetic diseases and that the origin of new mutations may beinfluenced by both genomic imprinting effects and the increasednumber of cell divisions in spermatogenesis compared with oogenesis. 相似文献
76.
Makoto Takano Frances M. Ashcroft 《Pflügers Archiv : European journal of physiology》1996,431(4):625-631
We studied the block of whole-cell ATP-sensitive K+ (KATP) currents in mouse pancreatic-cells produced by external Ba2+. Ba2+ produced a time- and voltage-dependent block of KATP currents, both the rate and extent of the block increasing with hyperpolarization. With 5.6 mM [K+]o, the relationship between the steady-state KATP current and [Ba2+]o, was fit by the Hill equation with aK
d of 12.5 ± 2.8 M at –123 mV and of 0.18 ± 0.02 mM at –62 mV The Hill coefficient (n) was close to 1 at all potentials indicating that binding of a single Ba2+ ion is sufficient to block the channel. When [K+]o was raised to 28 mM the Kd was little changed (12.4 ± 4.1 gM at –123 mV 0.27 ± 0.05 mM at –62 mV) and n was unaffected, suggesting that K+ does not interact with the Ba2+ binding site. The kinetics of Ba2+ block were slow, 10 M Ba2+ blocking the KATP current with a time constant of 20 ms at –123 mV in 28 mM [K+]o. The blocking rate constant was calculated as 1.7 mM–1 ms–1 and the unblocking rate as 0.02 ms–1, at –123 mV The data are discussed in terms of a model in which Ba2+ binds to a site at the external mouth of the channel to inhibit the KATP channel. 相似文献
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HLA-B5 and B35 CREG antigens include HLA-B35, B51, B52, B53, and B78. Recent studies suggest that the genes encoding the HLA-B5, B35 CREG, and HLA-B58 antigens share a common ancestor. We sequenced the exons of the genes encoding HLA-B51, B53, and B58 from American black individuals and the gene HLA-B52 encoding from an Arabic individual, and compared them with previously reported sequences of HLA-B51 (B*5101) and HLA-B52 (B*5201) from Japanese, HLA-B53 (B*5301) from an Algerian, and HLA-B58 (B*5801) from a Sardinian. The sequences of the genes from the American black and Arabic individuals were identical to those from the other races. These findings support the hypothesis that these antigens have evolved prior to divergence of the major ethnic groups. 相似文献
78.
Gloyn AL Reimann F Girard C Edghill EL Proks P Pearson ER Temple IK Mackay DJ Shield JP Freedenberg D Noyes K Ellard S Ashcroft FM Gribble FM Hattersley AT 《Human molecular genetics》2005,14(7):925-934
Neonatal diabetes can either remit and hence be transient or else may be permanent. These two phenotypes were considered to be genetically distinct. Abnormalities of 6q24 are the commonest cause of transient neonatal diabetes (TNDM). Mutations in KCNJ11, which encodes Kir6.2, the pore-forming subunit of the ATP-sensitive potassium channel (K(ATP)), are the commonest cause of permanent neonatal diabetes (PNDM). In addition to diabetes, some KCNJ11 mutations also result in marked developmental delay and epilepsy. These mutations are more severe on functional characterization. We investigated whether mutations in KCNJ11 could also give rise to TNDM. We identified the three novel heterozygous mutations (G53S, G53R, I182V) in three of 11 probands with clinically defined TNDM, who did not have chromosome 6q24 abnormalities. The mutations co-segregated with diabetes within families and were not found in 100 controls. All probands had insulin-treated diabetes diagnosed in the first 4 months and went into remission by 7-14 months. Functional characterization of the TNDM associated mutations was performed by expressing the mutated Kir6.2 with SUR1 in Xenopus laevis oocytes. All three heterozygous mutations resulted in a reduction in the sensitivity to ATP when compared with wild-type (IC(50) approximately 30 versus approximately 7 microM, P-value for is all <0.01); however, this was less profoundly reduced than with the PNDM associated mutations. In conclusion, mutations in KCNJ11 are the first genetic cause for remitting as well as permanent diabetes. This suggests that a fixed ion channel abnormality can result in a fluctuating glycaemic phenotype. The multiple phenotypes associated with activating KCNJ11 mutations may reflect their severity in vitro. 相似文献
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Wymbs Frances Doctoroff Greta L. Chacko Anil Sternheim Gillian 《Prevention science》2021,22(7):866-879
Prevention Science - The impact of evidence-based parenting health promotion programs is threatened by limited enrollment and attendance. We used a discrete choice experiment (DCE) to examine how... 相似文献