全文获取类型
收费全文 | 703篇 |
免费 | 47篇 |
国内免费 | 22篇 |
专业分类
儿科学 | 34篇 |
妇产科学 | 16篇 |
基础医学 | 55篇 |
口腔科学 | 9篇 |
临床医学 | 71篇 |
内科学 | 134篇 |
皮肤病学 | 14篇 |
神经病学 | 11篇 |
特种医学 | 113篇 |
外科学 | 219篇 |
综合类 | 18篇 |
预防医学 | 23篇 |
眼科学 | 9篇 |
药学 | 23篇 |
中国医学 | 2篇 |
肿瘤学 | 21篇 |
出版年
2019年 | 6篇 |
2018年 | 11篇 |
2017年 | 6篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2014年 | 13篇 |
2013年 | 13篇 |
2012年 | 7篇 |
2011年 | 14篇 |
2010年 | 21篇 |
2009年 | 23篇 |
2008年 | 18篇 |
2007年 | 25篇 |
2006年 | 13篇 |
2005年 | 14篇 |
2004年 | 9篇 |
2003年 | 15篇 |
2002年 | 18篇 |
2001年 | 20篇 |
2000年 | 15篇 |
1999年 | 26篇 |
1998年 | 31篇 |
1997年 | 44篇 |
1996年 | 30篇 |
1995年 | 18篇 |
1994年 | 17篇 |
1993年 | 17篇 |
1992年 | 8篇 |
1991年 | 15篇 |
1990年 | 18篇 |
1989年 | 28篇 |
1988年 | 17篇 |
1987年 | 15篇 |
1986年 | 13篇 |
1985年 | 18篇 |
1984年 | 14篇 |
1983年 | 14篇 |
1982年 | 13篇 |
1980年 | 20篇 |
1979年 | 12篇 |
1978年 | 6篇 |
1977年 | 12篇 |
1976年 | 13篇 |
1975年 | 12篇 |
1974年 | 6篇 |
1971年 | 6篇 |
1970年 | 5篇 |
1969年 | 6篇 |
1968年 | 11篇 |
1967年 | 5篇 |
排序方式: 共有772条查询结果,搜索用时 703 毫秒
1.
The human visual system is amenable to a number of adaptive processes; one such process, or collection of processes, is the adaptation to blur. Blur adaptation can be observed as an improvement in vision under degraded conditions, and these changes occur relatively rapidly following exposure to blur. The potential important future directions of this research area and the clinical implications of blur adaptation are discussed. 相似文献
2.
Presidential address: Natural selection in university surgery 总被引:1,自引:0,他引:1
A H Harken 《Surgery》1986,100(2):129-133
3.
4.
V P Addonizio C A Fisher J F Strauss V A Ewan F R Rickles E F Rosato A H Harken W Y Inouye 《Surgery》1987,101(6):753-762
Disseminated intravascular coagulation invariably accompanies placement of peritoneovenous (LeVeen) shunts, which suggests that ascitic fluid contains procoagulant material capable of activating blood coagulation. In this study, we identified thrombogenic activity in human ascites and the hemostatic pathway by which it acts. Peritoneal fluid was removed percutaneously from patients with ascites due to various causes. Four fractions were prepared by centrifugation: cells, a low-speed, cell-free fluid, a high-speed supernatant, and the precipitate from the high-speed centrifugation. Cellular fractions from all ascitic fluids shortened a one-stage clotting time of normal pooled plasma by 68% in comparison with saline solution and endotoxin controls. Similarly, the cell-free fluids also shortened the clotting time of normal pooled plasma by 41%. The cellular and cell-free fractions shortened the clotting time of factor VIII-deficient plasma but failed to demonstrate procoagulant activity in factor VII-deficient plasma. These fractions had no effect on platelet aggregation or the platelet release reaction. The high-speed precipitate was dissociated by ethylenediaminetetra-acetate (EDTA) into fluid phase and precipitate, both of which demonstrated procoagulant activity. Furthermore, high-speed precipitate contained protein, phospholipid, and sterol in proportions similar to those of plasma membranes and contained membrane-bound vesicles as identified by means of electron microscopy. This material could be rendered inactive by heating to 100 degrees C for 2 minutes or by incubation with phospholipase C for 15 minutes. Finally, the ability of the high-speed precipitate to shorten the clotting time was prevented by preincubation with a monoclonal antibody, which is known to inhibit the procoagulant activity of human tissue factor. We suggest that several entities contribute to the procoagulant properties of human ascites, with procoagulant material deriving at least in part from peritoneal cells. The sedimentable procoagulant factor appears to be associated with cellular membranes or membrane fragments and is thromboplastin-like in its chemical composition, immunoreactivity, and substrate specificity. 相似文献
5.
Hausegger KA; Cragg AH; Lammer J; Lafer M; Fluckiger F; Klein GE; Sternthal MH; Pilger E 《Radiology》1994,190(1):199
6.
Serum ionic fluoride levels in haemodialysis and continuous ambulatory peritoneal dialysis patients 总被引:1,自引:1,他引:0
al-Wakeel JS; Mitwalli AH; Huraib S; al-Mohaya S; Abu-Aisha H; Chaudhary AR; al-Majed SA; Memon N 《Nephrology, dialysis, transplantation》1997,12(7):1420-1424
High serum fluoride (F-) in patients with chronic renal failure (CRF) and
end-stage renal disease (ESRD) is associated with risk of renal
osteodystrophy and other bone changes. This study was done to determine F-
in normal healthy controls and patients with ESRD on haemodialysis (HD) or
peritoneal dialysis (PD). Seventeen healthy controls (12 males, 5 females)
and 39 ESRD patients on dialysis (17 males, 22 females) were recruited in
the study in a community with 47.4 +/- 3.28 microM/l (range 44-51 microM/l)
of F- content in drinking water. Control subjects showed a mean serum F-
concentration of 1.08 +/- 0.350 microM/l. Males in control group showed
slightly higher F- levels (1.15 +/- 0.334, range 0.55-1.9 microM/l) than
females (0.92 +/- 0.370, range 0.6-1.5 microM/l). Mean serum F-
concentration did not correlate significantly with age and sex among
control subjects, whereas such correlation was observed in patients with
ESRD on dialysis. Mean serum F- concentration was significantly higher in
patients on dialysis (2.67 +/- 1.09, range 0.8-5.2 microM/l) than normal
controls. When grouped according to sex, the mean serum F- concentration in
males (3.05 +/- 1.04, range 1.8-5.2 microM/l) was significantly higher than
females (2.38 +/- 1.08, range 0.8-5.2 microM/l). When patients were grouped
according to age, it was observed that F- concentration was significantly
higher in patients with age groups 21-70 (2.86 +/- 1.05) than those with
age group 13-20 years (1.42 +/- 0.531). Thus F- concentration correlated
with age and sex, being higher in males and above 20 years. Despite
appreciable clearance of F- (39-90%) across the peritoneum, patients on
CAPD showed higher serum F- concentration than those on HD (3.1 +/- 1.97 vs
2.5 +/- 1.137 microM/l). Of the total 39 patients on dialysis 39% had their
serum F- concentration above 3.0 microM/l, posing the risk of renal
osteodystrophy.
相似文献
7.
L S Joffe M P Glode M K Gutierrez A Wiesenthal D W Luckey L Harken 《The Pediatric infectious disease journal》1992,11(9):730-735
The purpose of this study was to determine whether children hospitalized with a primary diagnosis of infection were more likely than matched controls to have had a diphtheria-tetanus toxoids-pertussis immunization in the 30 days before hospitalization of the case. Cases were less likely than controls to have received an immunization (P = 0.003). They were also less likely to have been breast-fed (P < 0.001) and to have had a well-child care clinic visit (P = 0.01). Cases were significantly more likely to be preterm (< 38 weeks gestation), low birth weight (< 2500 g) and attending day care than their matched nonhospitalized controls (P = 0.003, 0.03 and 0.002, respectively). This study demonstrates no association between receipt of diphtheria-tetanus toxoids-pertussis immunization and subsequent hospitalization for an infectious illness. 相似文献
8.
9.
10.
Focal liver lesions: characterization with triphasic spiral CT 总被引:15,自引:1,他引:14