全文获取类型
收费全文 | 649篇 |
免费 | 31篇 |
国内免费 | 75篇 |
专业分类
儿科学 | 52篇 |
妇产科学 | 16篇 |
基础医学 | 47篇 |
口腔科学 | 12篇 |
临床医学 | 69篇 |
内科学 | 134篇 |
皮肤病学 | 38篇 |
神经病学 | 47篇 |
特种医学 | 91篇 |
外科学 | 48篇 |
综合类 | 81篇 |
预防医学 | 20篇 |
药学 | 79篇 |
中国医学 | 1篇 |
肿瘤学 | 20篇 |
出版年
2021年 | 7篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 12篇 |
2017年 | 9篇 |
2016年 | 9篇 |
2015年 | 5篇 |
2014年 | 7篇 |
2013年 | 13篇 |
2012年 | 24篇 |
2011年 | 19篇 |
2010年 | 26篇 |
2009年 | 24篇 |
2008年 | 26篇 |
2007年 | 70篇 |
2006年 | 35篇 |
2005年 | 23篇 |
2004年 | 22篇 |
2003年 | 21篇 |
2002年 | 17篇 |
2001年 | 17篇 |
2000年 | 19篇 |
1999年 | 13篇 |
1998年 | 25篇 |
1997年 | 24篇 |
1996年 | 27篇 |
1995年 | 20篇 |
1994年 | 12篇 |
1993年 | 20篇 |
1992年 | 7篇 |
1991年 | 9篇 |
1990年 | 4篇 |
1989年 | 16篇 |
1988年 | 6篇 |
1987年 | 15篇 |
1986年 | 10篇 |
1985年 | 15篇 |
1984年 | 8篇 |
1983年 | 11篇 |
1982年 | 13篇 |
1981年 | 10篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 9篇 |
1976年 | 7篇 |
1975年 | 7篇 |
1974年 | 4篇 |
1964年 | 3篇 |
1957年 | 3篇 |
排序方式: 共有755条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Carlos Bada Nilton Yhuri Carreazo Juan Pablo Chalco Luis Huicho 《Revista paulista de medicina》2007,125(3):150-154
CONTEXT AND OBJECTIVE: Many children with acute lower respiratory tract infections (ALRI) present to the emergency ward with concurrent wheezing. A chest x-ray is often requested to rule out pneumonia. We assessed inter-observer agreement in interpreting x-rays on such children. DESIGNS AND SETTING: Prospective consecutive case study at Instituto de Salud del Ni?o, Lima, Peru. METHODS: Chest x-rays were obtained from eligible children younger than two years old with ALRI and concurrent wheezing who were seen in the emergency ward of a nationwide pediatric referral hospital. The x-rays were read independently by three different pediatric residents who were aware only that the children had a respiratory infection. All the children had received inhaled beta-adrenergic agonists before undergoing chest x-rays. Lobar and complicated pneumonia cases were excluded from the study. RESULTS: Two hundred x-rays were read. The overall kappa index was 0.2. The highest individual kappa values for specific x-ray findings ranged from 0.26 to 0.34 for rib horizontalization and from 0.14 to 0.31 for alveolar infiltrate. Inter-observer variation was intermediate for alveolar infiltrate (kappa 0.14 to 0.21) and for air bronchogram (kappa 0.13 to 0.23). Reinforcement of the bronchovascular network (kappa 0.10 to 0.16) and air trapping (kappa 0.05 to 0.20) had the lowest agreement. CONCLUSIONS: There was poor inter-observer agreement for chest x-ray interpretation on children with ALRI and concurrent wheezing seen at the emergency ward. This may preclude reliable diagnosing of pneumonia in settings where residents make management decisions regarding sick children. The effects of training on inter-observer variation need further studies. 相似文献
5.
Background: The fabrication of dental prosthesis requires the transfer of interocclusal records from patient's mouth to semiadjustable articulators using different kinds of recording media. Any inaccuracy in these interocclusal records leads to occlusal errors in the final prosthesis. This study was conducted to evaluate the dimensional changes occurring in the interocclusal recording material over a given period of time and the material's resistance to compression during the cast mounting on the articulator. 相似文献
6.
7.
8.
7β-(6-取代-2-喹诺酮-3-乙酰氨基)头孢菌素的合成 总被引:1,自引:0,他引:1
以6-取代-2-喹诺酮-3-乙酸为侧链,用CDI法和潘化酯法与7-ADCA,7-ACA,7-ACT,和7-ACD缩合,合成了16个新的7β-(6-取代-2-喹诺酮-3-乙酰氨基)头孢菌素类化合物,通过溶媒转提,葡聚糖凝胶(Sephadex LH-20)柱层析及离心薄层层析分离精制,得到纯品。初步体外抑菌试验表明:新化合物对革兰氏阳性及某些阴性菌具有高度敏感性。大多数化合物对所试试验菌的抗菌活性与头孢唑啉和青霉素G钠相当,有些比它们还强。 相似文献
9.
10.
Detection of reactive oxygen species (ROS) and apoptosis in human fragmented embryos 总被引:8,自引:2,他引:8
Yang HW; Hwang KJ; Kwon HC; Kim HS; Choi KW; Oh KS 《Human reproduction (Oxford, England)》1998,13(4):998-1002
In human in-vitro fertilization (IVF)-embryo transfer, the in-vitro culture
environment differs from in-vivo conditions in that the oxygen
concentration is higher, and in such conditions the mouse embryos show a
higher concentration of reactive oxygen species (ROS) in simple culture
media. ROS are believed to cause damage to cell membranes and DNA
fragmentation in somatic cells. This study was conducted to ascertain the
level of H2O2 concentration within embryos and the morphological features
of cell damage induced by H2O2. A total of 62 human oocytes and embryos (31
fragmented, 15 non-fragmented embryos, 16 unfertilized oocytes) was
obtained from the IVF-embryo transfer programme. The relative intensity of
H2O2 concentrations within embryos was measured using
2',7'-dichlorodihydrofluorescein diacetate by Quanti cell 500 fluorescence
imaging and DNA fragmentation was observed with transmission electron
microscopy and an in-situ apoptosis detection kit. The H2O2 concentrations
were significantly higher in fragmented embryos (72.21 +/- 9.62, mean +/-
SEM) compared to non-fragmented embryos (31.30 +/- 3.50, P < 0.05) and
unfertilized oocytes (30.75 +/- 2.67, P < 0.05). Apoptosis was observed
only in fragmented embryos, and was absent in non-fragmented embryos.
Electron microscopic findings confirmed apoptotic bodies and cytoplasmic
condensation in the fragmented blastomeres. We conclude that there is a
direct relationship between increased H2O2 concentration and apoptosis, and
that further studies should be undertaken to confirm these findings.
相似文献