全文获取类型
收费全文 | 760篇 |
免费 | 53篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 46篇 |
儿科学 | 49篇 |
妇产科学 | 6篇 |
基础医学 | 73篇 |
口腔科学 | 42篇 |
临床医学 | 59篇 |
内科学 | 125篇 |
皮肤病学 | 27篇 |
神经病学 | 19篇 |
特种医学 | 218篇 |
外科学 | 37篇 |
综合类 | 34篇 |
预防医学 | 34篇 |
眼科学 | 5篇 |
药学 | 20篇 |
肿瘤学 | 41篇 |
出版年
2018年 | 5篇 |
2017年 | 6篇 |
2016年 | 8篇 |
2015年 | 7篇 |
2014年 | 14篇 |
2013年 | 10篇 |
2012年 | 8篇 |
2011年 | 11篇 |
2010年 | 19篇 |
2009年 | 20篇 |
2008年 | 20篇 |
2007年 | 15篇 |
2006年 | 19篇 |
2005年 | 7篇 |
2004年 | 12篇 |
2003年 | 10篇 |
2002年 | 6篇 |
2001年 | 16篇 |
2000年 | 11篇 |
1999年 | 16篇 |
1998年 | 40篇 |
1997年 | 44篇 |
1996年 | 40篇 |
1995年 | 35篇 |
1994年 | 23篇 |
1993年 | 31篇 |
1992年 | 23篇 |
1991年 | 18篇 |
1990年 | 15篇 |
1989年 | 26篇 |
1988年 | 33篇 |
1987年 | 44篇 |
1986年 | 27篇 |
1985年 | 16篇 |
1984年 | 8篇 |
1983年 | 15篇 |
1982年 | 17篇 |
1981年 | 20篇 |
1980年 | 17篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1977年 | 9篇 |
1976年 | 21篇 |
1975年 | 10篇 |
1934年 | 4篇 |
1933年 | 3篇 |
1932年 | 2篇 |
1930年 | 3篇 |
1927年 | 4篇 |
1926年 | 4篇 |
排序方式: 共有835条查询结果,搜索用时 15 毫秒
81.
We have found that the addition of 10 mM inorganic phosphate to DHA in CPD-adenine maintains ATP levels at normal or higher than normal values for six weeks of storage. 2,3-DPG values are slightly lowered by the extra phosphate, but are still maintained at approximately half normal for four weeks by the DHA. The addition of a higher phosphate concentration, 20 mM, to DHA produced lower levels of ATP and 2,3-DPG than those observed with 10 mM phosphate, although both levels were better than in the CPD-adenine control. pH values in this experiment were lowest in the three preservatives containing DHA, probably indicating increased lactate production due to metabolism of this triose sugar, in addition to dextrose present in CPD. 相似文献
82.
83.
84.
85.
P Dutta U Mitra DR Saha SK Niyogi B Manna SK Bhattacharya 《Acta paediatrica (Oslo, Norway : 1992)》1999,88(8):822-826
A hospital-based case-control study was carried out to clarify the characteristics of mucoid presentation of acute enterocolitis in children. One hundred sixty-eight cases of acute mucoid enterocolitis (study population) were compared with 200 cases of watery diarrhoea and 118 cases of blood dysentery (control groups) on the basis of clinical characteristics and findings on stool examination. Study and control groups were comparable with respect to age, body weight and nutritional status. There was no significant difference in clinical characteristics (duration of diarrhoea, stool frequency, presence of vomiting, fever and dehydration) between patients suffering from mucoid enterocolitis and blood dysentery. However, watery diarrhoea patients had significantly high frequencies of vomiting (p = 0.00001) and dehydration (p 相似文献
86.
DR Brewster MJ Manary IS Menzies EV O'Loughlin RL Henry 《Archives of disease in childhood》1997,76(3):236-241
Intestinal permeability can be assessed non-invasively using the lactulose-rhamnose (L-R) test, which is a reliable measure of small intestinal integrity. AIMS: To determine risk factors for abnormal intestinal permeability in kwashiorkor, and to measure changes in L-R ratios with inpatient rehabilitation. DESIGN: A case-control study of 149 kwashiorkor cases and 45 hospital controls. The L-R test was adapted to study kwashiorkor in Malawi, with testing at weekly intervals during nutritional rehabilitation. Urine sugars were measured by thin layer chromatography in London. RESULTS: The initial geometric mean L-R ratios (x100) (with 95% confidence interval) in kwashiorkor were 17.3 (15.0 to 19.8) compared with 7.0 (5.6 to 8.7) for controls. Normal ratios are < 5, so the high ratios in controls indicate tropical enteropathy syndrome. Abnormal permeability in kwashiorkor was associated with death, oliguria, sepsis, diarrhoea, wasting and young age. Diarrhoea and death were associated with both decreased L-rhamnose absorption (diminished absorptive surface area) and increased lactulose permeation (impaired barrier function) whereas nutritional wasting affected only L-rhamnose absorption. Despite, clinical recovery, mean L-R ratios improved little on treatment, with mean weekly ratios of 16.3 (14.0 to 19.0), 13.3 (11.1 to 15.9) and 14.4 (11.0 to 18.8). CONCLUSION: Abnormal intestinal permeability in kwashiorkor correlates with disease severity, and improves only slowly with nutritional rehabilitation. 相似文献
87.
88.
Cerebral blood flow relationships associated with a difficult tone recognition task in trained normal volunteers 总被引:2,自引:2,他引:0
Holcomb HH; Medoff DR; Caudill PJ; Zhao Z; Lahti AC; Dannals RF; Tamminga CA 《Cerebral cortex (New York, N.Y. : 1991)》1998,8(6):534-542
Tone recognition is partially subserved by neural activity in the right
frontal and primary auditory cortices. First we determined the brain areas
associated with tone perception and recognition. This study then examined
how regional cerebral blood flow (rCBF) in these and other brain regions
correlates with the behavioral characteristics of a difficult tone
recognition task. rCBF changes were assessed using H2(15)O positron
emission tomography. Subtraction procedures were used to localize
significant change regions and correlational analyses were applied to
determine how response times (RT) predicted rCBF patterns. Twelve trained
normal volunteers were studied in three conditions: REST, sensory motor
control (SMC) and decision (DEC). The SMC-REST contrast revealed bilateral
activation of primary auditory cortices, cerebellum and bilateral inferior
frontal gyri. DEC-SMC produced significant clusters in the right middle and
inferior frontal gyri, insula and claustrum; the anterior cingulate gyrus
and supplementary motor area; the left insula/claustrum; and the left
cerebellum. Correlational analyses, RT versus rCBF from DEC scans, showed a
positive correlation in right inferior and middle frontal cortex; rCBF in
bilateral auditory cortices and cerebellum exhibited significant negative
correlations with RT These changes suggest that neural activity in the
right frontal, superior temporal and cerebellar regions shifts back and
forth in magnitude depending on whether tone recognition RT is relatively
fast or slow, during a difficult, accurate assessment.
相似文献
89.
90.