全文获取类型
收费全文 | 908192篇 |
免费 | 50169篇 |
国内免费 | 1333篇 |
专业分类
耳鼻咽喉 | 10631篇 |
儿科学 | 30500篇 |
妇产科学 | 21168篇 |
基础医学 | 131622篇 |
口腔科学 | 21934篇 |
临床医学 | 77812篇 |
内科学 | 170435篇 |
皮肤病学 | 17133篇 |
神经病学 | 68003篇 |
特种医学 | 35559篇 |
外国民族医学 | 76篇 |
外科学 | 138588篇 |
综合类 | 17587篇 |
现状与发展 | 2篇 |
一般理论 | 169篇 |
预防医学 | 71382篇 |
眼科学 | 19259篇 |
药学 | 64621篇 |
3篇 | |
中国医学 | 3004篇 |
肿瘤学 | 60206篇 |
出版年
2021年 | 5811篇 |
2018年 | 31217篇 |
2017年 | 24791篇 |
2016年 | 28777篇 |
2015年 | 8844篇 |
2014年 | 11488篇 |
2013年 | 16615篇 |
2012年 | 28257篇 |
2011年 | 44099篇 |
2010年 | 32404篇 |
2009年 | 24544篇 |
2008年 | 41894篇 |
2007年 | 46997篇 |
2006年 | 22815篇 |
2005年 | 23498篇 |
2004年 | 24617篇 |
2003年 | 25373篇 |
2002年 | 22519篇 |
2001年 | 36799篇 |
2000年 | 37666篇 |
1999年 | 30684篇 |
1998年 | 8179篇 |
1997年 | 7043篇 |
1996年 | 7161篇 |
1995年 | 6822篇 |
1994年 | 6315篇 |
1993年 | 5763篇 |
1992年 | 23116篇 |
1991年 | 23110篇 |
1990年 | 22509篇 |
1989年 | 22222篇 |
1988年 | 20156篇 |
1987年 | 19547篇 |
1986年 | 18583篇 |
1985年 | 17423篇 |
1984年 | 12784篇 |
1983年 | 10818篇 |
1982年 | 6026篇 |
1979年 | 11622篇 |
1978年 | 8202篇 |
1977年 | 6853篇 |
1976年 | 6669篇 |
1975年 | 7274篇 |
1974年 | 8540篇 |
1973年 | 8154篇 |
1972年 | 7662篇 |
1971年 | 7135篇 |
1970年 | 6917篇 |
1969年 | 6352篇 |
1968年 | 5812篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
994.
Brain morphology in first-episode schizophrenic-like psychotic patients: a quantitative magnetic resonance imaging study 总被引:5,自引:0,他引:5
L E DeLisi A L Hoff J E Schwartz G W Shields S N Halthore S M Gupta F A Henn A K Anand 《Neuropsychopharmacology》1991,29(2):159-175
Brain morphology was examined using magnetic resonance imaging in 30 first-episode patients with a schizophreniclike psychosis, 15 chronic schizophrenics, and 20 neurological controls. Statistical analyses of computer-generated measurements of regions of interest were controlled for gender, age, social class, and total brain volume. Lateral ventricular size was increased in both first-episode and chronic schizophrenic patients, with greater significance on the left than on the right side. Only the chronic patients, however, had reduced temporal lobe size, which also was greater on the left side. No major correlations of regional brain morphological measurements with cognitive functioning were found, although some measurements of verbal memory were correlated with parahippocampal size. This is a report of a preliminary study that suggests that some morphological brain changes may be present at the time of first treatment for a psychotic illness, whereas others may occur later in the course of illness. Future prospective studies may determine the clinical significance of these changes and whether they progress with the development of illness chronicity. 相似文献
995.
996.
R A Wallace L Wallace M Harrold D Miller N J Uretsky 《Biochemical pharmacology》1989,38(12):2019-2025
Although a structural feature common to all dopaminergic agonists and antagonists is a side-chain basic amino group, it is unclear whether this moiety binds to the D-1 dopamine (DA) receptor in the charged or uncharged form. To obtain information on this point, we synthesized permanently charged dimethylsulfonium and quaternary ammonium analogs of chlorpromazine and DA and determined whether these compounds can bind to the D-1 receptor by measuring their abilities to inhibit the binding of SCH 23390, a D-1 receptor antagonist. Chlorpromazine and the dimethylsulfonium and trimethylammonium analogs of chlorpromazine were found to inhibit the binding of [3H]SCH 22390, which was maximally inhibited to the same extent by all three compounds. In addition, inhibition curves for the compounds fit a one-site binding model, indicating binding to a single class of sites. However, while the permanently charged chlorpromazine analogs were able to inhibit [3H]SCH-23390 binding, they were considerably less potent than chlorpromazine. DA and dimethyl DA were also able to inhibit [3H]SCH 23390 binding. However, the permanently charged dimethylsulfonium and trimethylammonium analogs of DA were ineffective in inhibiting [3H]SCH 23390 binding. In addition, the permanently uncharged methylsulfide analog did not inhibit binding. These studies show that permanently charged analogs of chlorpromazine can bind to the striatal D-1 receptor, which is consistent with an anionic recognition site on the D-1 receptor that interacts with antagonists in the cationic form. In addition, it appears that a nitrogen atom is not required for binding to the D-1 receptor, since the sulfonium analog of chlorpromazine bound to the receptor to the same extent as chlorpromazine. However, since the permanently charged or uncharged analogs of DA did not bind to the D-1 receptor, it is still unclear as to whether the charged form of a dopaminergic agonist can bind. The lower potency or ineffectiveness of the permanently charged analogs compared to the parent amines (chlorpromazine, DA, dimethyl DA) in binding to the D-1 receptor may reflect the inability of the permanently charged analogs to undergo hydrogen binding with the anionic site of the receptor. 相似文献
997.
998.
999.
1000.
Paramyxovirus-like inclusions in two cases of pycnodysostosis 总被引:1,自引:0,他引:1
We describe the biochemical and histological features of two related patients with pycnodysostosis. Examination of bone biopsies taken from both patients showed the presence of large nonfunctional osteoclasts which contained paramyxovirus-like inclusions similar in size and arrangement to those found in Paget's disease of bone. No radiographic, histologic or biochemical evidence for Paget's disease was found in either patient. The presence of osteoclast inclusions may not be specific for Paget's disease, therefore, and could be the result rather than the cause of abnormal osteoclast metabolism. 相似文献