全文获取类型
收费全文 | 827篇 |
免费 | 28篇 |
国内免费 | 1篇 |
专业分类
耳鼻咽喉 | 12篇 |
儿科学 | 56篇 |
妇产科学 | 16篇 |
基础医学 | 88篇 |
口腔科学 | 18篇 |
临床医学 | 82篇 |
内科学 | 178篇 |
皮肤病学 | 21篇 |
神经病学 | 11篇 |
特种医学 | 156篇 |
外科学 | 66篇 |
综合类 | 22篇 |
一般理论 | 1篇 |
预防医学 | 49篇 |
眼科学 | 14篇 |
药学 | 45篇 |
肿瘤学 | 21篇 |
出版年
2018年 | 7篇 |
2014年 | 11篇 |
2013年 | 19篇 |
2012年 | 6篇 |
2011年 | 8篇 |
2010年 | 28篇 |
2009年 | 21篇 |
2008年 | 6篇 |
2005年 | 11篇 |
2004年 | 6篇 |
2003年 | 8篇 |
2001年 | 7篇 |
2000年 | 11篇 |
1999年 | 9篇 |
1998年 | 38篇 |
1997年 | 34篇 |
1996年 | 30篇 |
1995年 | 27篇 |
1994年 | 32篇 |
1993年 | 24篇 |
1992年 | 11篇 |
1991年 | 14篇 |
1990年 | 15篇 |
1989年 | 26篇 |
1988年 | 24篇 |
1987年 | 23篇 |
1986年 | 12篇 |
1985年 | 20篇 |
1984年 | 10篇 |
1983年 | 13篇 |
1982年 | 23篇 |
1981年 | 12篇 |
1980年 | 13篇 |
1979年 | 6篇 |
1978年 | 7篇 |
1977年 | 13篇 |
1976年 | 17篇 |
1975年 | 11篇 |
1972年 | 5篇 |
1970年 | 6篇 |
1963年 | 6篇 |
1960年 | 7篇 |
1959年 | 17篇 |
1958年 | 23篇 |
1957年 | 23篇 |
1956年 | 19篇 |
1955年 | 33篇 |
1954年 | 22篇 |
1949年 | 10篇 |
1948年 | 19篇 |
排序方式: 共有856条查询结果,搜索用时 15 毫秒
1.
2.
Placental malaria. I. Pathological classification 总被引:10,自引:0,他引:10
Pregnant women are more likely to contract malaria than their non-pregnant counterparts. The aim of this study was to develop a simple classification system for the histopathological diagnosis of placental malaria infection applicable to placentas collected in field conditions. The placentas were classified into four groups depending on the presence and disribution of parasites and malaria pigment: active infection, active-chronic infection, past-chronic infection, not infected. The frequency of parasitized placentas (26.4%) was in keeping with the prevalence of placental parasitaemia documented in epidemiological studies. An additional 29.8% placentas showed pigment in fibrin only, indicating pastchronic infection. Chronic placental malaria infection was most common in primigravidae, possibly reflecting ineffective clearance of parasites from the placenta. Seasonal fluctuations between infection categories support progression of placental infection with delayed clearance of pigment from fibrin. The proposed classification system has allowed diagnosis of different categories of placental malaria infection by two independent observers. A stadardized method of diagnosis may enhance understanding of placental pathology and reduced birth weight in malaria infection during pregnancy. 相似文献
3.
4.
5.
6.
7.
8.
9.
Steenbergen EJ; Verhagen OJ; van Leeuwen EF; van den Berg H; von dem Borne AE; van der Schoot CE 《Blood》1995,86(2):692-702
Crosslineage T-cell receptor delta (TCR delta) rearrangements are widely used as tumor markers for the follow up of minimal residual disease in childhood B-precursor acute lymphoblastic leukemia (ALL) by polymerase chain reaction (PCR). The major drawback of this approach is the risk of false-negative results due to clonal evolution. We investigated the stability of V delta 2D delta 3 rearrangements in a group of 56 childhood B-precursor ALL patients by PCR and Southern blot analysis. At the PCR level, V delta 2D delta 3-to-J alpha rearranged subclones (one pathway for secondary TCR delta recombination) were demonstrated in 85.2% of V delta 2D delta 3-positive patients tested, which showed that small subclones are present in the large majority of patients despite apparently monoclonal TCR delta Southern blot patterns. Sequence analysis of V delta 2D delta 3J alpha rearrangements showed a biased J alpha gene usage, with HAPO5 and J alpha F in 26 of 32 and 6 of 32 clones, respectively. Comparison of V delta 2D delta 3 rearrangement status between diagnosis and first relapse showed differences in seven of eight patients studied. In contrast, from first relapse onward, no clonal changes were observed in six patients studied. To investigate the occurrence of crosslineage TCR delta rearrangements in normal B and T cells, fluorescence-activated cell sorter-sorted peripheral blood CD19+/CD3- and CD19-/CD3+ cell populations from three healthy donors were analyzed. V delta 2D delta 3 rearrangements were detected at low frequencies in both B and T cells, which suggests that V delta 2-to-D delta 3 joining also occurs during normal B-cell differentiation. A model for crosslineage TCR delta rearrangements in B-precursor ALL is deduced that explains the observed clonal changes between diagnosis and relapse and is compatible with multistep leukemogenesis of B-precursor ALL. 相似文献