全文获取类型
收费全文 | 266篇 |
免费 | 13篇 |
国内免费 | 5篇 |
专业分类
耳鼻咽喉 | 35篇 |
儿科学 | 9篇 |
妇产科学 | 15篇 |
基础医学 | 33篇 |
口腔科学 | 3篇 |
临床医学 | 16篇 |
内科学 | 48篇 |
皮肤病学 | 8篇 |
神经病学 | 5篇 |
特种医学 | 45篇 |
外科学 | 30篇 |
综合类 | 3篇 |
预防医学 | 8篇 |
眼科学 | 2篇 |
药学 | 16篇 |
肿瘤学 | 8篇 |
出版年
2021年 | 5篇 |
2020年 | 2篇 |
2018年 | 2篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 10篇 |
2012年 | 8篇 |
2011年 | 8篇 |
2010年 | 12篇 |
2009年 | 7篇 |
2008年 | 8篇 |
2007年 | 3篇 |
2006年 | 9篇 |
2005年 | 11篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2002年 | 6篇 |
2001年 | 4篇 |
1999年 | 6篇 |
1998年 | 14篇 |
1997年 | 10篇 |
1996年 | 13篇 |
1995年 | 6篇 |
1994年 | 7篇 |
1993年 | 9篇 |
1992年 | 6篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 12篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1969年 | 2篇 |
1968年 | 3篇 |
1966年 | 2篇 |
1927年 | 2篇 |
1912年 | 2篇 |
1886年 | 1篇 |
1885年 | 1篇 |
1884年 | 3篇 |
1882年 | 2篇 |
排序方式: 共有284条查询结果,搜索用时 15 毫秒
51.
52.
Peptic ulcer due to Zollinger-Ellison syndrome is a rare entity. In this case report a 55-year-old man had a medical history of esophageal reflux, vomiting, and diarrhea for 10 years. Despite continuous medication with a proton pump inhibitor, no complete recovery from symptoms was achieved. A diagnosis of gastrinoma was at first not considered. After discontinuation of the proton pump inhibitor for only a few days, the strong stimulation of the gastrinoma led to fulminant hydrochloric acid burn of the distal esophagus with iatrogenic or spontaneous perforation at the esophagogastral junction. We describe the operative treatment as a two-stage reconstruction with colon interposition and resection of the primary tumor in the duodenum. 相似文献
53.
LDE Wijnberger TG Krediet J Egberts F van Bel 《Acta paediatrica (Oslo, Norway : 1992)》2001,90(5):569-572
In a study of endogenous nitric oxide production in growth-retarded, very preterm newborns (<32 wk GA), urinary NOx/creatinine ratio and plasma guanosine 3',5'-cyclic monophosphate levels were determined during the early neonatal period. Newborns were divided into three groups: appropriate-for-gestational-age (AGA, n = 19), moderately small-for-gestational-age (SGA, n = 13) and severely SGA (n = 6) infants. Severely SGA infants showed significant higher values of nitric oxide derivatives during the first 24 h of life compared with the other groups. CONCLUSION: An increased NO production is found in SGA infants during the first 24 h after birth. This may reflect an increased intrauterine nitric oxide production in the feto-placental circulation found in cases with intrauterine growth retardation, 相似文献
54.
血小板激活因子对大鼠脑血管通透性的影响及药物的保护作用 总被引:1,自引:0,他引:1
颈内动脉注射血小板激活因子(PAF),再给伊文思蓝,可见脑实质染色程度加深,而颈内动脉只注射伊文思蓝,脑实质未见染色。而我们合成的新药SZ-1可剂量依赖性地抑制PAF诱导的脑实质伊文思蓝染色程度的加深。在体外培养的脑微血管平滑肌细胞上,PAF能显著刺激~(14)-花生四烯酸的释放,而SZ-1能剂量依赖性地抑制这种释放,提示PAF在脑内产生的损害除与其他因素相关外,还与其刺激花生四烯酸释放有密切关系,SZ-1对PAF引起的脑部损害有保护作用。 相似文献
55.
Cooper TG Hellenkemper B 《国外医学(计划生育.生殖健康分册)》2010,29(3):221-224
本研究的目的是提高用过氧化物酶试验检测精液中的白细胞时所得的圆形细胞数量的精确度。精液样本的圆形细胞浓度在(0.6~6)×10^6/mL之间,降低精液的稀释度,增加被测悬浮液的体积。1+5(1:6)的稀释度适合于测量过氧化物酶活性,并能为细胞检测提供足够清晰的背景。在该稀释度下,测定Neubauer-改良精子计数板两边所有18个网格中的细胞数量,额定细胞浓度为(1.9~3.3)×10^6/mL的10个样本中只有3个样本的圆形细胞数/〉400个。由于更低浓度的精子稀释液不适合测定圆形细胞或其过氧化物酶反应产物,所以无法精确测量(抽样误差5%)参考下限值(1×10^6/mL)。结果表明,正是由于测定精液中的10个样本中圆形细胞很难精确到1×10^6/mL,所以白细胞精液症临界值的确定一直存在诸多分歧。因此需要建立一些统计学上合理的参考限。 相似文献
56.
BACKGROUND: Preoperative autologous blood donation is accepted as a standard of care for radical prostatectomy. Acute normovolemic hemodilution (ANH) is an alternative method for obtaining autologous blood. The cost and benefits of these two autologous blood-collection techniques are compared. STUDY DESIGN AND METHODS: Thirty consecutive patients scheduled for radical prostatectomy underwent ANH to a target hematocrit level of 28 percent. Blood was transfused in the perioperative period to maintain the hematocrit level > 25 percent. Hematocrit levels, transfusion outcomes and costs, and postoperative outcomes for these patients (hemodilution group) were compared with a matched patient cohort who preoperatively donated 3 units of blood for autologous use in prostatectomy surgery (nonhemodilution group, n = 30). RESULTS: Thirty patients underwent ANH to a hematocrit level of 28.7 +/− 1.7 percent, and 1740 +/− 346 mL (3.5 +/− 0.7 units) of blood were collected. Three (10%) of the patients in each cohort had allogeneic blood exposure. Transfusion costs were 73 percent higher for the nonhemodilution group patients than for the hemodilution group patients ($330 +/− $100 vs. $191 +/− $55, p < 0.001). No differences were found in postoperative outcomes. CONCLUSION: An integrated blood conservation program utilizing hemodilution and a defined transfusion trigger can decrease the requirement for preoperative donation of blood for autologous use in radical prostatectomy. Point-of-care autologous blood procurement is more cost-effective than preadmission donation of autologous blood units. 相似文献
57.
58.
Mechanisms of leukemic cell clonal dominance may include aberrations of transmembrane signaling. In particular, neoplastic transformation has been associated with reduced capacity for hormone-stimulated adenylate cyclase activity. In the present study, prostaglandin E, a hormonal activator of adenylate cyclase that has antiproliferative activity in myeloid cells, and cholera toxin, an adenylate cyclase agonist that functions at a postreceptor site by activating the adenylate cyclase stimulatory GTP-binding protein (Gs), were studied for antiproliferative activity in two murine myeloid cell lines. FDC-P1, an interleukin 3 (IL 3)-dependent myeloid cell line and a tumorigenic IL 3- independent subline, FI, were resistant to these antiproliferative agents. The in vitro ability of the "differentiation" agent, sodium butyrate, to reverse their resistance to adenylate cyclase agonists was studied. The antiproliferative action of butyrate involved augmentation of transmembrane adenylate cyclase activity. Increased adenylate cyclase catalyst activity was the primary alteration of this transmembrane signaling group leading to the functional inhibitory effects on leukemia cells, although alterations in regulatory G- proteins appear to play a secondary role. 相似文献
59.
Riboldi P; Gaidano G; Schettino EW; Steger TG; Knowles DM; Dalla-Favera R; Casali P 《Blood》1994,83(10):2952-2961
We analyzed the reactivity and the structure of the VH and VL segments of two IgM monoclonal antibodies (MoAbs) produced by spontaneously in vitro outgrowing cell lines, HBL-2 and HBL-3, established from two acquired immunodeficiency syndrome (AIDS) patients with Epstein-Barr virus (EBV)-negative Burkitt's lymphoma (BL). These B-cell clones were representative of the respective neoplastic parental clones, as determined by immunophenotypic and molecular genetic analysis. The IgM MoAbs were highly specific for the i determinant on red blood cells (cold agglutinins), but bound none of the other eight self and nine foreign antigens (Ags) tested, including those most commonly recognized by natural antibodies or autoantibodies. Structural analysis showed that the IgM MoAb VH segment sequences were 93.5% and 84.2% identical with that of the germline VH4-21 gene, which encodes the vast majority of cold agglutinins that are specific for the i/l carbohydrate Ag and are produced under chronic lymphoproliferative conditions. The HBL-2 MoAb VH4-21 gene segment was juxtaposed with 20P3 and JH6 genes and paired with a V lambda 1 segment, the sequence of which was 95.5% identical to that of the germline Humlv117 gene; the HBL-3 MoAb VH4-21 gene segment was juxtaposed with DXP'1 and JH5 genes and paired with a V lambda 1 segment, the sequence of which was 86.7% identical to that of the germline Humlv1L1 gene. The high degree of conservation of the VH4-21 gene in the human population, the nature of the nucleotide differences in the expressed VH4-21 segments, and the presence of nucleotide substitutions in the HBL-2 and HBL-3 IgM MoAb JH and/or J lambda segments suggested that the MoAb V segments underwent a process of somatic hypermutation. This was formally shown in the HBL-3 MoAb VH segment, by differentially targeted polymerase chain reaction amplification of the HBL-3 MoAb-producing cell genomic DNA. In addition, cloning and sequencing of the genomic DNA from fibroblasts of the same patient whose neoplastic B cells gave rise to the HBL-3 cell line yielded a germline copy of the VH4-21 gene. Thus, the expression of VH4-21 gene products may be involved in a self Ag-driven process of clonal B-cell expansion and selection associated with BL in these AIDS patients. 相似文献
60.
Apoptosis is the major form of cell death associated with the action of chemotherapeutic agents on tumor cells, and therefore the expression of genes that interfere with apoptosis can have important consequences for the efficacy of therapeutic approaches. Here we show that K562, a chronic myelogenous leukemia (CML) cell line expressing the BCR-ABL fusion protein, are resistant to the induction of apoptosis by a number of agents and conditions. Antisense oligodeoxynucleotides corresponding to the translation start of bcr downregulate bcr-abl protein in these cells and render them susceptible to induction of apoptosis by chemotherapeutic agents or serum deprivation. Expression of a temperature sensitive v-Abl protein reverses the effects of the antisense oligonucleotides, such that the cells remain resistant to apoptosis at the permissive temperature. These data indicate that bcr- abl acts as an anti-apoptosis gene in CML cells and suggests that the effect is dependent on the abl kinase activity in this chimeric protein. Inhibition of bcr-abl to render CML cells susceptible to apoptosis can be combined with therapeutic drugs and/or treatment capable of inducing apoptosis to provide an effective strategy for elimination of these cells. 相似文献