全文获取类型
收费全文 | 1259篇 |
免费 | 103篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 9篇 |
儿科学 | 116篇 |
妇产科学 | 23篇 |
基础医学 | 159篇 |
口腔科学 | 23篇 |
临床医学 | 151篇 |
内科学 | 225篇 |
皮肤病学 | 18篇 |
神经病学 | 67篇 |
特种医学 | 155篇 |
外科学 | 225篇 |
综合类 | 14篇 |
预防医学 | 79篇 |
眼科学 | 1篇 |
药学 | 45篇 |
肿瘤学 | 74篇 |
出版年
2023年 | 7篇 |
2022年 | 11篇 |
2021年 | 12篇 |
2020年 | 12篇 |
2019年 | 10篇 |
2018年 | 17篇 |
2017年 | 16篇 |
2016年 | 18篇 |
2015年 | 24篇 |
2014年 | 29篇 |
2013年 | 45篇 |
2012年 | 49篇 |
2011年 | 57篇 |
2010年 | 50篇 |
2009年 | 45篇 |
2008年 | 41篇 |
2007年 | 55篇 |
2006年 | 51篇 |
2005年 | 37篇 |
2004年 | 34篇 |
2003年 | 46篇 |
2002年 | 33篇 |
2001年 | 37篇 |
2000年 | 38篇 |
1999年 | 37篇 |
1998年 | 53篇 |
1997年 | 50篇 |
1996年 | 35篇 |
1995年 | 20篇 |
1994年 | 34篇 |
1993年 | 26篇 |
1992年 | 29篇 |
1991年 | 17篇 |
1990年 | 18篇 |
1989年 | 29篇 |
1988年 | 37篇 |
1987年 | 23篇 |
1986年 | 16篇 |
1985年 | 17篇 |
1984年 | 21篇 |
1983年 | 17篇 |
1982年 | 21篇 |
1981年 | 14篇 |
1980年 | 12篇 |
1979年 | 9篇 |
1978年 | 9篇 |
1977年 | 14篇 |
1976年 | 8篇 |
1975年 | 5篇 |
1929年 | 4篇 |
排序方式: 共有1384条查询结果,搜索用时 0 毫秒
941.
Three children with leukaemia (one with acute myeloid, two with acute lymphoblastic leukaemia) developed pneumatosis intestinalis during cytostatic treatment. The aetiology of pneumatosis intestinalis in these children could not be elucidated. Pneumatosis intestinalis may be caused by entry of gas into a bowel wall which is altered by steroid or cytostatic treatment. Otherwise, anaerobic bacteria may produce gas in the intestinal walls, therefore we treated all children with metronidazol. 相似文献
942.
943.
The effects of perinatal methadone exposure on the development of noradrenergic responses in the brain were examined by assessing the ability of intracisternally administered norepinephrine to stimulate 33Pi incorporation into phospholipids in vivo; the effect of norepinephrine is mediated by alpha1-receptors juxtaposed to noradrenergic nerve terminals. Although there was no difference in basal (unstimulated) incorporation of 33Pi, a deficit in norepinephrine-induced stimulation of incorporation was found throughout the preweaning period in offspring of dams treated daily with methadone beginning in midgestation. This effect was not seen when methadone was given during the postnatal period. Since perinatal methadone exposure also delays development of presynaptic catecholaminergic nerve terminals in the brain, these results support the view that perinatal exposure to methadone depresses overall central noradrenergic synaptic function; however, the effects on presynaptic development and on receptor-mediated responses appear to be separable in that they display differences in the critical age periods of sensitivity to perturbation by the drug. 相似文献
944.
Body composition in systemic lupus erythematosus 总被引:1,自引:0,他引:1
The objectives were to determine the body composition, and the effects of
disease and corticosteroid therapy on body composition, in a population of
female patients with systemic lupus erythematosus (SLE). All female SLE
patients managed through a single centre were invited to participate in a
cross-sectional study of body composition. Data were collected by
standardized interview and examination, and review of medical records. Body
composition was assessed by dual-energy X-ray absorptiometry (DXA).
Eighty-two subjects were evaluated, 30 of whom were post-menopausal.
Univariate linear regression analysis revealed a significant association of
reduced fat-free mass with SLE severity [as measured by the Systemic Lupus
International Collaborative Clinics (SLICC)] (P = 0.020), a history of
corticosteroid exposure (P = 0.043) and age (P = 0.048). Reduced total body
bone mineral density (BMD) was also significantly associated with SLICC (P
< 0.001) and corticosteroid exposure (P = 0.017), and with age (P <
0.001), post-menopausal status (P = 0.003) and the duration of menopause (P
< 0.001). Stepwise multiple linear regression analysis revealed a
significant association between fat-free mass and total body, lumbar spine
and femoral neck BMD (P = 0.007, P = 0.025, P = 0.003, respectively). Fat
mass was significantly associated only with lumbar spine BMD (P = 0.008).
In this SLE population, disease severity and corticosteroid exposure were
independently associated with a negative effect both on total body BMD and
on fat-free mass. Fat-free mass was a significant predictor of lumbar
spine, femoral neck and total body BMD.
相似文献
945.
E S Orwoll R M Weigel S K Oviatt M R McClung L J Deftos 《The American journal of clinical nutrition》1988,48(1):127-130
The effect of small calcium and vitamin D supplements on mineral metabolism in normal persons is unclear. To investigate the biochemical response to these medications, we administered 1000 mg Ca and 25 micrograms cholecalciferol per day or a placebo to 92 normal men for 1 y. The Ca and cholecalciferol were tolerated well. 25-Hydroxycholecalciferol [25-(OH)D] and 24,25-dihydroxycholecalciferol [24,25-(OH)2D] levels rose in treated subjects; there was no definite change in 1,25-(OH)2D concentrations. The average difference in 25-(OH)D levels between treated and untreated subjects was 30 nmol/L at 1 y. Fasting serum Ca, alkaline phosphatase, creatinine, and parathyroid hormone levels and the fasting urinary excretion of Ca, phosphorus and cAMP, were not affected. However, 24-h urinary Ca excretion was higher in the supplemented group (3.5 +/- 1.9 vs 4.7 +/- 1.7 mmol/d, p = 0.006). Serum P concentrations were slightly higher in the supplemented group at 1 y. In normal men small calcium and cholecalciferol supplements are safe, provide adequate vitamin D nutrition and apparently increase net gastrointestinal Ca absorption. 相似文献
946.
Screening blood donors for gastrointestinal illness: a strategy to eliminate carriers of Yersinia enterocolitica 总被引:3,自引:0,他引:3
BJ Grossman ; P Kollins ; PM Lau ; JL Perreten ; RJ Bowman ; S Malcolm ; WM Palko 《Transfusion》1991,31(6):500-501
Recent reports of fatal transfusion-associated Yersinia enterocolitica sepsis prompted a study of the feasibility of adding a question to the routine donor health history as a method of reducing this risk. In three American Red Cross blood centers, 11,323 donors were asked one of two questions about gastrointestinal symptoms during their health history screenings. Affirmative responses were obtained from 0.6 or 4.0 percent of the donors, depending on how the question was asked. In one center, more than 6 percent of donors gave affirmative answers. The efficacy of asking a relatively simple question about gastrointestinal symptoms as a way of preventing Y. enterocolitica should be evaluated further, because relatively large numbers of donors may respond affirmatively. Other methods of reducing the risk of transfusion-associated Y. enterocolitica infection should be pursued. 相似文献
947.
CT scans were assessed for ability to detect abdominal extent of tumor in 17 patients with renal cell carcinoma. Computed tomography has a unique advantage over other imaging modalities in that it can distinguish between tumors confined to Gerota's fascia and those which show contiguous spread, invading adjacent structures such as muscles, liver and the periaortic and pericaval regions. CT can also detect regional lymph node metastases and tumor extension into the renal vein and inferior vena cava. Preoperative assessment of tumor extent helps to determine patient prognosis, surgical approach and whether transcatheter tumor embolization should be used. 相似文献
948.
In this paper the results of our investigations on the nerve-vessel relations in the region of jugular foramen are briefly presented. For the purpose of comparison, the pertinent findings published by other authors are included as well. Particular attention has been given to the topographical measurements, various shapes and classification of jugular foramen. The inferior petrosal sinus together with its nerve-vessel topography and venous connections have been considered to a certain extent. Finally a detailed discussion of the results has been presented. 相似文献
949.
950.
In vitro function and post-transfusion survival of granulocytes collected by continuous-flow centrifugation and by filtration leukapheresis 总被引:3,自引:0,他引:3
The function of granulocytes collected by continuous-flow centrifugation (CFC) and by filtration leukapheresis (FL) was studied in vitro, and the post-transfusion recovery and intravascular survival of these cells was studied by autologous transfusion in normal donors. Granulocytes collected by both FL and CFC leukapheresis (CFCL) functioned normally in the quantitative nitroblue tetrazolium, oxygen consumption, and chemotaxis assays. Bacterial killing was slightly but consistently decreased in FL but not CFCL granulocytes. The post- transfusion recovery of control granulocytes collected by ordinary phlebotomy averaged 52% in eight transfusions, compared with 34% for six CFCL granulocyte concentrates and 16% for six FL concentrates. The intravascular half-times were 3.8 hr for phlebotomy and 3.0 hr for CFCL granulocytes. FL granulocytes had survival curves which were nonlinear and a single half-life could not be calculated. The average half-time 30 min after transfusion was 1.3 hr, and 3 hr after transfusion it was 2.6 hr. Granulocytes collected by FL had a mild impairment of bacterial killing, decreased post-transfusion recovery, and altered intravascular kinetics. None of these abnormalities was found in granulocytes collected by CFCL. 相似文献