全文获取类型
收费全文 | 223篇 |
免费 | 12篇 |
国内免费 | 34篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 12篇 |
妇产科学 | 2篇 |
基础医学 | 27篇 |
口腔科学 | 1篇 |
临床医学 | 45篇 |
内科学 | 30篇 |
皮肤病学 | 3篇 |
神经病学 | 20篇 |
特种医学 | 40篇 |
外科学 | 25篇 |
综合类 | 13篇 |
预防医学 | 7篇 |
药学 | 34篇 |
中国医学 | 1篇 |
肿瘤学 | 8篇 |
出版年
2023年 | 2篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2014年 | 8篇 |
2013年 | 11篇 |
2012年 | 3篇 |
2011年 | 5篇 |
2010年 | 11篇 |
2009年 | 9篇 |
2008年 | 10篇 |
2007年 | 25篇 |
2006年 | 10篇 |
2005年 | 11篇 |
2004年 | 5篇 |
2003年 | 7篇 |
2002年 | 2篇 |
2001年 | 7篇 |
2000年 | 4篇 |
1998年 | 9篇 |
1997年 | 16篇 |
1996年 | 10篇 |
1995年 | 11篇 |
1994年 | 8篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 7篇 |
1989年 | 3篇 |
1988年 | 10篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 6篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有269条查询结果,搜索用时 15 毫秒
51.
Mesude Tosun Nagihan Inan Hasan Tahsin Sarisoy Gur Akansel Sevtap Gumustas Yeşim Gürbüz Ali Demirci 《European journal of radiology》2013
Objective
To evaluate the diagnostic accuracy of liver apparent diffusion coefficient (ADC) measured with conventional diffusion-weighted imaging (CDI) and diffusion tensor imaging (DTI) for the diagnosis of liver fibrosis and inflammation.Materials and methods
Thirty-seven patients with histologic diagnosis of chronic viral hepatitis and 34 healthy volunteers were included in this prospective study. All patients and healthy volunteers were examined by 3 T MRI. CDI and DTI were performed using a breath-hold single-shot echo-planar spin echo sequence with b factors of 0 and 1000 s/mm2. ADCs were obtained with CDI and DTI. Histopathologically, fibrosis of the liver parenchyma was classified with the use of a 5-point scale (0–4) and inflammation was classified with use of a 4-point scale (0–3) in accordance with the METAVIR score. Quantitatively, signal intensity and the ADCs of the liver parenchyma were compared between patients stratified by fibrosis stage and inflammation grade.Results
With a b factor of 1000 s/mm2, the signal intensity of the cirrhotic livers was significantly higher than those of the normal volunteers. In addition, ADCs reconstructed from CDI and DTI of the patients were significantly lower than those of the normal volunteers. Liver ADC values inversely correlated with fibrosis and inflammation but there was only statistically significant for inflammatory grading. CDI performed better than DTI for the diagnosis of fibrosis and inflammation.Conclusion
ADC values measured with CDI and DTI may help in the detection of liver fibrosis. They may also give contributory to the inflammatory grading, particularly in distinguishing high from low grade. 相似文献52.
53.
54.
Increased trinucleotide repeat instability with advanced maternal age 总被引:15,自引:14,他引:1
Nucleotide repeat instability is associated with an increasing number of
cancers and neurological disorders. The mechanisms that govern repeat
instability in these biological disorders are not well understood. To
examine genetic aspects of repeat instability we have introduced an
expanded CAG trinucleotide repeat into transgenic mice. We have detected
intergenerational CAG repeat instability in transgenic mice only when the
transgene was maternally transmitted. These intergenerational instabilities
increased in frequency and magnitude as the transgenic mother aged.
Furthermore, triplet repeat variations were detected in unfertilized
oocytes and were comparable with those in the offspring. These data show
that maternal repeat instability in the transgenic mice occurs after
meiotic DNA replication and prior to oocyte fertilization. Thus, these
findings demonstrate that advanced maternal age is an important factor for
instability of nucleotide repeats in mammalian DNA.
相似文献
55.
Recombinant human granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood stem/progenitor cells (PBPC) have replaced bone marrow (BM) harvests for autologous transplantation after myeloablative therapy in cancer patients. G-CSF-mobilized PBPC from healthy donors contain one log excess of T lymphocytes representing a potential risk for graft-versus-host disease (GVHD). However, recent pilot clinical studies of G-CSF-mobilized allogeneic PBPC transplantation have shown rapid haematological recovery and no severe acute GVHD except in a very few cases. Therefore, the risk of inducing severe acute GVHD is not as high as was expected during the pioneering period of allogeneic PBPC transplantation.The present study was performed to address the possible reasons for the rapid haematological recovery and the absence of severe acute GVHD observed after allogeneic PBPC transplantation by comparing the contents and subsets of CD3+ and CD34+ G-CSF-mobilized PBPC (n = 31) with those of BM (n = 26) allografts from healthy adult donors. The present results revealed that the phenotypic profiles of CD3+ and CD34+ cells differ between PBPC and BM allografts. The single PBPC leukapheresis product contained 10 times more mononuclear cells, 1.5 times more CD34+ cells, 5.5 times more CD3+ T lymphocytes, 3 times more CD19+ B lymphocytes and 3.8 times more CD14+ monocytes than the single BM harvest. Both CD34+CD33+ myeloid progenitor cells and CD34+HLA-DR- long-term reconstituting haemopoietic stem cells were significantly increased in the CD34+ G-CSF-mobilized PBPC compared with the CD34+ BM cells; median 73.1% and 30.4% vs 60.6% and 5.0%, respectively, P < 0.01.The percentage of CD3+ cells coexpressing CD4 (T helper/inducer) was similar in both PBPC and BM allografts, 47.2% and 45.6%, respectively, whereas the percentage of CD3+ cells coexpressing CD8 (T suppressor/cytotoxic) was significantly decreased in PBPC compared with BM; 37.0% vs 55.9%, p < 0.01. 相似文献
56.
57.
Simsek S; Faas BH; Bleeker PM; Overbeeke MA; Cuijpers HT; van der Schoot CE; von dem Borne AE 《Blood》1995,85(10):2975-2980
Rh (rhesus) D is the dominant antigen of the Rh blood group system. Recent advances in characterization of the nucleotide sequence of the cDNA(s) encoding the Rh D polypeptide allow the determination of the Rh D genotype at the DNA level. This can be of help in cases in which red blood cells are not available for phenotyping, eg, when in concerns a fetus. We have tested three independent DNA typing methods based on the polymerase chain reaction (PCR) for their suitability to determine the Rh D genotype. DNA derived from peripheral blood mononuclear cells from 234 Rh-phenotyped healthy donors (178 Rh D positive and 56 Rh D negative) was used in the PCR. The Rh D genotypes, as determined with a method based on the allele-specific amplification of the 3' noncoding region of the Rh D gene described by Bennett et al (N Engl J Med 329:607, 1993), were not concordant with the serologically established phenotypes in all cases. We have encountered 5 discrepant results, ie, 3 false-positive and 2 false-negative (a father and child). Rh D genotyping with the second method was performed by PCR amplification of exon 7 of the D gene with allele-specific primers. In all donors phenotyped as D positive tested so far (n = 178), the results of molecular genotyping with this method were concordant with the serologic results, whereas a false-positive result was obtained in one of the D-negative donors (also false-positive in the first method). Complete agreement was found between genotypes determined in the third method, based on a 600-bp deletion in intron 4 of the Rh D gene described by Arce et al (Blood 82:651, 1993), and serologically determined phenotypes. The Rh blood group system is complex, and unknown polymorphisms at the DNA level are expected to exist. Therefore, although genotypes determined by the method of Arce et al were in agreement with serotypes, it cannot yet be regarded as the golden standard. More experience with this or other methods is still needed. 相似文献
58.
Metabolic crenation of red cells is reversible; on addition of nutrients, echinocytes recover the normal discoid shape. When the shape recovery takes place in the presence of reducing agents such as dithiothreitol (DTT), morphological change continues until the cells are stomatocytic. The degree of stomatocytosis varies, depending on the cell morphology when the nutrients and reducing agent are added. DTT has minimal effect on the shape of normal discocytes, but in its presence, mildly echinocytic cells become slightly cupped and advanced- stage echinocytes become severely stomatocytic. DTT must be present continuously for development and retention of stomatocytosis; echinocytes preincubated with or metabolically depleted in DTT do not become stomatocytic when supplemented in the absence of DTT, and DTT- induced stomatocytes revert to discocytes when the reducing agent is removed. DTT has no effect on adenosine triphosphate synthesis or equilibrium cell glutathione levels, and the induced stomatocytosis is not inhibited by excluding oxygen from cells during depletion. Spectrin phosphorylation and phosphate turnover are not affected by DTT. The echinocyte-to-discocyte transformation coincides with phosphorylation of membrane inner monolayer lipids (diacylglycerol to phosphatidic acid and phosphatidylinositol to phosphatidylinositol-4,5-bisphosphate). Overphosphorylation of these phospholipids is not responsible for the exaggerated shape recovery seen with reducing agents; phosphorylation of inner monolayer lipids proceeds identically in the presence and absence of DTT. 相似文献
59.
An association has been established between human Ia-like antigenic determinants, expression during DNA synthesis on multipotential (CFU- GEMM) and erythroid (BFU-E) progenitor cells, and the regulatory action of acidic isoferritins in vitro. Treatment of human bone marrow cells with monoclonal anti-Ia (NE1-011) plus complement inhibited colony formation of CFU-GEMM) and BFU-E by 50%-70%. Reduction of colonies was similar whether bone marrow cells were exposed to anti-Ia plus complement, high specific tritiated thymidine (3HTdr), or acidic isoferritins. No further decrease was apparent with 3HTdr or acidic isoferritins after Ia-antigen+ CFU-GEMM or BFU-E were removed, or with anti-Ia plus complement or acidic isoferritins after S-phase CFU-GEMM or BFU-E were removed. Anti-Ia, in the absence of complement, had no effect on colony formation but blocked the inhibition of CFU-GEMM and BFU-E by acidic isoferritins. Demonstration of Ia-antigens on BFU-E and inhibition of BFU-E by acidic isoferritins appeared to require the presence of phytohemmagglutinin leukocyte conditioned medium (PHA-LCM) in the culture medium during the 14-day incubation period. these results implicate Ia-antigen+ cells, acidic isoferritins, and PHA-LCM in the regulation of multipotential and erythroid progenitor cells in vitro. 相似文献
60.
Pekdemir M Yilmaz S Ersel M Sarisoy HT 《The American journal of emergency medicine》2008,26(3):383.e1-383.e2
Headache represents up to 4% of all emergency department (ED) visits. Emergency physicians generally are concerned with identifying those patients whose headaches are caused by life-threatening conditions. Cerebral venous sinus thrombosis may be difficult to diagnose clinically because of its various and nonspecific manifestations. The most frequent but least specific symptom of sinus thrombosis is severe headache, which is present in more than 90% of adult patients. In the case report we present, a patient had severe headache and was diagnosed until third ED visit at different hospitals. He had one of the most unusual causes of headache, that is, cerebral venous sinus thrombosis due to hyperthyroidism. 相似文献