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41.
Normal ovaries and functional cysts: MR appearance 总被引:6,自引:1,他引:5
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43.
Linkage of a familial platelet disorder with a propensity to develop myeloid malignancies to human chromosome 21q22.1-22.2 总被引:2,自引:4,他引:2
Ho CY; Otterud B; Legare RD; Varvil T; Saxena R; DeHart DB; Kohler SE; Aster JC; Dowton SB; Li FP; Leppert M; Gilliland DG 《Blood》1996,87(12):5218-5224
Linkage analysis was performed on a large pedigree with an autosomal dominant platelet disorder and a striking propensity in affected family members to develop hematologic malignancy, predominantly acute myelogenous leukemia. We report the linkage of the autosomal dominant platelet disorder to markers on chromosome 21q22. Four genetic markers completely cosegregate with the trait and yield maximum logarithm of difference scores ranging from 4.9 to 10.5 (theta = .001). Two flanking markers, D21S1265 and D21S167, define a critical region for the disease locus of 15.2 centimorgan. Further analysis of this locus may identify a gene product that affects platelet production and function and contributes to the molecular evolution of hematologic malignancy. 相似文献
44.
Splenic lymphoma with villous lymphocytes involves B cells with extensively mutated Ig heavy chain variable region genes 总被引:4,自引:1,他引:4
Splenic lymphoma with villous lymphocytes (SLVL) is a recently defined subgroup of chronic B-cell lymphoproliferative diseases. The characteristic morphology of the tumor cells, together with phenotypic and cytogenetic findings, indicate that it is a distinct entity, but the nature of the cell or origin and its relationship to other low- grade lymphomas is unclear. For B-cell tumors, analysis of the variable region heavy chain (VH) genes used to encode the clonal Ig has shown marked differences between histologic categories, both in gene usage and extent of somatic mutation. An investigation of VH genes used in five typical cases of SLVL has shown somatic hypermutation from germline sequences in all cases, indicating that the cell of origin has been exposed to the hypermutation mechanism. However, no clonal heterogeneity was detectable, demonstrating that the tumor cell does not accumulate further mutations. These characteristics are similar to those found in mature postfollicular B cells, such as plasma cells. The distribution of mutations leading to replacement amino acids differed among the cases, with three of five cases showing clear evidence for antigen selection. 相似文献
45.
Elevation of serum cystathionine levels in patients with cobalamin and folate deficiency 总被引:14,自引:0,他引:14
Homocysteine can be methylated to form methionine by the cobalamin- (Cbl) and folate-dependent enzyme, methionine synthase; serum levels of total homocysteine are elevated in greater than 95% of patients with either Cbl or folate deficiency. Homocysteine can also condense with serine to form cystathionine in a pyridoxal phosphate-dependent reaction catalyzed by cystathionine beta-synthase. Cystathionine is subsequently cleaved to cysteine and alpha-ketobutyrate by the pyridoxal phosphate-dependent enzyme gamma-cystathionase. To assess levels of cystathionine in Cbl and folate deficiency, we developed a new capillary gas chromatographic-mass spectrometric assay and measured cystathionine in the serum of normal subjects and patients with clinically confirmed deficiencies of these vitamins. The normal range for serum cystathionine was 65 to 301 nmol/L (median = 126 nmol/L) for 50 normal blood donors. In 30 patients with clinically confirmed Cbl deficiency, values for cystathionine ranged from 208 nmol/L to 2,920 nmol/L (median = 816 nmol/L) and 26 (87%) had levels above the normal range. In 20 patients with clinically confirmed folate deficiency, cystathionine concentrations ranged from 138 nmol/L to 4,150 nmol/L (median = 1,560 nmol/L) and 19 (95%) had values above the normal range. Five homozygotes for cystathionine beta-synthase deficiency had high values for serum-total homocysteine and low or low-normal values for serum cystathionine that ranged from 30 nmol/L to 114 nmol/L even though they were on treatment with pyridoxine and had partially responded. One patient with a defect in the synthesis of 5-CH3- tetrahydrofolate and five patients with defects in the synthesis of CH3- Cbl had high values for serum-total homocysteine and high values for cystathionine that ranged from 311 nmol/L to 1,500 nmol/L even though they were on treatment with folic acid and Cbl, respectively, and had partially responded. We conclude that levels of cystathionine are evaluated in the serum of most patients with Cbl and folate deficiency and that they are useful in the differential diagnosis of an elevated serum-total homocysteine level. 相似文献
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47.
Congenital heart lesions involving the right ventricular outflow tract (RVOT) are a common problem in paediatric cardiology. These patients need multiple surgical interventions in the form of valved conduits over a lifetime. Surgical re-valvulation was the standard treatment option until the introduction of percutaneous pulmonary valves over a decade ago. These valves can be used to prolong the lifespan of conduits and reduce the number of re-operations. The Melody® valve (Medtronic, Minneapolis, MN, USA) was introduced as the first dedicated percutaneous pulmonary valve. Percutaneous pulmonary valves can be implanted successfully and have the advantage of short hospitalisations. We describe the first three Melody® valve implantations in Africa. 相似文献
48.
Differential expression of CD11b/CD18 (Mo1) and myeloperoxidase genes during myeloid differentiation 总被引:6,自引:0,他引:6
During the course of differentiation of early human myeloid cells toward monocytes and granulocytes, cell surface expression of the cell adhesion molecule, CD11b/CD18 (Mo1) increases dramatically and expression of myeloperoxidase (MPO), a bacteriocidal enzyme, decreases markedly. Using the inducible promyelocytic cell line HL-60 as a model, we studied the mRNA expression of these genes. Differentiation of these cells along both a monocytic and a granulocytic pathway demonstrated that the mRNA levels of the two subunits of CD11b/CD18 increased in a pattern temporally and quantitatively similar to the increase in cell surface expression of this heterodimer. In contrast, the expression of MPO mRNA decreased in a temporal and quantitative pattern similar to the known decrease in MPO protein during differentiation, suggesting that regulation of these myeloid-specific proteins may occur at the level of mRNA expression. These findings have important implications with regard to the nature of the block in differentiation in acute nonlymphocytic leukemia and the regulation of myeloid gene expression. 相似文献
49.
Stromal cell-associated erythropoiesis 总被引:5,自引:0,他引:5
A novel cover slip-transfer culture system was designed to study the functional roles of stromal cells in hemopoiesis, particularly erythropoiesis. Human bone marrow stromal cell colonies were allowed to develop on small glass cover slips in liquid medium. The cover slips, along with the stromal cell colonies and progenitors attached to them were then transferred to a new tissue culture dish and overlaid with methylcellulose culture medium. No exogenous colony-stimulating factors except erythropoietin were supplied. Large erythroid bursts, comprising multiple subcolonies, developed on the stromal cells. In order to determine if stromal fibroblasts together with erythropoietin and serum proteins could support erythroid development, human bone marrow cells depleted of monocytes, macrophages, and T lymphocytes were allowed to adhere to monolayers of a homogeneous fibroblastoid human stromal cell strain ST-1 grown on cover slips. The cover slips were then washed to remove nonadherent cells, transferred to a new culture dish, and overlaid with methylcellulose culture medium containing fetal calf serum and erythropoietin. In this modified system as well, primitive erythroid progenitors migrated extensively on and within the stroma to form huge colonies of hemoglobinized erythroblasts that proceeded to enucleate. Our results indicate that (1) ST-1 cells together with serum proteins and erythropoietin can support the development of large erythroid bursts; (2) erythroid progenitors and precursors adhere to and migrate on and within the extracellular matrix elaborated by ST-1 cells; (3) erythroid progenitors are more adherent to the ST-1 cells or the extracellular matrix than are the more mature cells and possibly the myeloid progenitors. 相似文献
50.
Monocyte antigen CD14 is a phospholipid anchored membrane protein 总被引:30,自引:1,他引:30
A cDNA clone encoding the human monocyte antigen CD14 was isolated by transient expression in COS cells of a cDNA library prepared from phorbol diester-treated HL60 cells. RNA blot analysis showed abundant expression of a single mRNA species in mature monocytes and an increased expression of the mRNA following induction of differentiation in leukemic cell lines. The DNA blot hybridization pattern was consistent with a single-copy gene. The predicted amino acid sequence lacks the characteristic transmembrane domain and stop transfer motif of conventionally anchored membrane proteins. COS cells transfected with the CD14 cDNA released virtually all CD14 protein in soluble form following treatment with glycosyl phosphatidylinositol-specific phospholipase C, and CD14 immunoreactivity was absent from the affected monocytes of a patient with paroxysmal nocturnal hemoglobinuria (PNH). The data show that, to the limit of experimental sensitivity, all monocyte CD14 is joined to the plasma membrane by a phosphatidylinositol phospholipid. 相似文献