全文获取类型
收费全文 | 1731篇 |
免费 | 140篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 6篇 |
儿科学 | 154篇 |
妇产科学 | 18篇 |
基础医学 | 225篇 |
口腔科学 | 47篇 |
临床医学 | 194篇 |
内科学 | 398篇 |
皮肤病学 | 23篇 |
神经病学 | 32篇 |
特种医学 | 470篇 |
外科学 | 102篇 |
综合类 | 28篇 |
预防医学 | 49篇 |
眼科学 | 13篇 |
药学 | 51篇 |
中国医学 | 3篇 |
肿瘤学 | 80篇 |
出版年
2022年 | 4篇 |
2021年 | 7篇 |
2020年 | 9篇 |
2019年 | 8篇 |
2018年 | 17篇 |
2017年 | 12篇 |
2016年 | 22篇 |
2015年 | 28篇 |
2014年 | 28篇 |
2013年 | 60篇 |
2012年 | 24篇 |
2011年 | 25篇 |
2010年 | 77篇 |
2009年 | 56篇 |
2008年 | 46篇 |
2007年 | 28篇 |
2006年 | 37篇 |
2005年 | 24篇 |
2004年 | 23篇 |
2003年 | 18篇 |
2002年 | 23篇 |
2001年 | 25篇 |
2000年 | 27篇 |
1999年 | 30篇 |
1998年 | 137篇 |
1997年 | 119篇 |
1996年 | 125篇 |
1995年 | 92篇 |
1994年 | 77篇 |
1993年 | 84篇 |
1992年 | 26篇 |
1991年 | 28篇 |
1990年 | 20篇 |
1989年 | 62篇 |
1988年 | 52篇 |
1987年 | 50篇 |
1986年 | 51篇 |
1985年 | 51篇 |
1984年 | 27篇 |
1983年 | 32篇 |
1982年 | 37篇 |
1981年 | 21篇 |
1980年 | 36篇 |
1979年 | 18篇 |
1978年 | 17篇 |
1977年 | 19篇 |
1976年 | 23篇 |
1975年 | 24篇 |
1971年 | 2篇 |
1966年 | 3篇 |
排序方式: 共有1893条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
995.
Lymphocyte subsets in a group of intensely transfused (greater than 10 units/year) patients on long-term hemodialysis were compared with those in a carefully controlled population of lightly transfused (1-10 units/year, no units during study period) long-term dialysis patients. The data confirm previous reports of lymphopenia and a symmetrical reduction of both T- and B-cell subpopulations in patients on long-term dialysis. Eleven (36.7%) of 30 intensely transfused dialysis (ITD) patients had a low T8 population when expressed as a percentage value, while 0 of 25 lightly transfused dialysis (LTD) control patients exhibited a low percentage of T8 cells. There were no significant absolute differences between the lymphocyte subsets in the ITD and LTD patients. These data contrast with previous reports of other groups of ITD patients in whom there was an observed increase in T8 cytotoxic suppressor cells. Our findings suggest that the immunologic effects of renal failure and long-term dialysis largely override the increase in T8 lymphocyte subsets observed in other groups of transfused patients. There is little difference between ITD and LTD patients, but both groups are significantly different from nontransfused controls. Further longitudinal studies are needed in completely untransfused patients to resolve the contribution of minimal transfusion therapy to the immunologic deficits observed in long-term dialysis patients. 相似文献
996.
RM Lane DCH MRCGP M Sweeney MRCP JA Henry FRCP 《International journal of clinical practice》1994,48(5):256-262
SUMMARY Cardiovascular and cerebrovascular disease are associated with a high incidence of depressive disorder. Despite this high level of co-morbidity, depressive disorders appear to go largely unrecognised and remain untreated. This may have serious consequences, as concomitant depression worsens the prognosis in patients with cardiovascular or cerebrovascular disease, increases medical costs, and delays return to work. Treatment with traditional tricyclic antidepressants is difficult in these patients because of the known cardiac effects. The favourable side-effect profiles of the 5-HT reuptake inhibitors suggest that they may offer therapeutic advantages, as they have little or no effect on cardiac conduction, do not cause orthostatic hypotension, and lack serious sequelae in overdose. The pharmacological profiles and the reduced potential of these newer antidepressant drugs to cause drug interaction show important differences that may be of clinical relevance in this patient population. 相似文献
997.
998.
van der Put NM; Thomas CM; Eskes TK; Trijbels FJ; Steegers-Theunissen RP; Mariman EC; De Graaf-Hess A; Smeitink JA; Blom HJ 《QJM : monthly journal of the Association of Physicians》1997,90(8):505-510
Folic acid intake reduces the risk of neural tube defects (NTDs). Although
the 677C-->T mutation in the 5,10-methylenetetrahydrofolate reductase
(MTHFR) gene is a risk factor for NTDs, it only partly explains the
elevated homocysteine levels in mothers of children with NTDs. We measured
vitamin B12, folate and homocysteine in patients with spina bifida (SB),
their parents, and in controls, to investigate which other enzymes of
homocysteine metabolism might be defective. Because homozygosity for the
677C-->T mutation causes decreased plasma folate and increased red-cell
folate (RCF) and plasma homocysteine levels, we excluded individuals
homozygous for that mutation. The remaining SB patients and their parents
still had lowered plasma folate and elevated total homocysteine levels, and
a small subset had decreased vitamin B12 levels. Red-cell folate was the
same in all groups, suggesting that dietary folate intake and its uptake
was normal. Risk of SB was increased at the 25th percentile of plasma
folate and at the 75th percentile of homocysteine values in SB patients and
their parents, and at the 5th and 25th percentiles of vitamin B12 in
mothers with SB- affected offspring. This underlines the functional
importance of homocysteine remethylation to methionine. There was no
correlation between vitamin B12 and homocysteine or RCF. In combination
with the lowered plasma folate (80-90% 5-methyltetrahydrofolate), our data
do not support a major involvement of methionine synthase in the aetiology
of SB. Our data rather favour the involvement of genetic variation at loci
coding for the formation of 5-methyltetrahydrofolate, such as MTHFR,
methylenetetrahydrofolate dehydrogenase or serine hydroxymethyltransferase.
相似文献
999.
Imaging of pregnancy-associated breast cancer 总被引:4,自引:0,他引:4
1000.
Acute mesenteric ischemia: diagnosis with contrast-enhanced CT 总被引:34,自引:1,他引:33