全文获取类型
收费全文 | 1043篇 |
免费 | 129篇 |
国内免费 | 1篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 25篇 |
妇产科学 | 16篇 |
基础医学 | 156篇 |
口腔科学 | 12篇 |
临床医学 | 183篇 |
内科学 | 222篇 |
皮肤病学 | 5篇 |
神经病学 | 70篇 |
特种医学 | 27篇 |
外科学 | 125篇 |
综合类 | 43篇 |
一般理论 | 1篇 |
预防医学 | 138篇 |
眼科学 | 2篇 |
药学 | 92篇 |
肿瘤学 | 54篇 |
出版年
2022年 | 7篇 |
2021年 | 19篇 |
2020年 | 8篇 |
2019年 | 15篇 |
2018年 | 28篇 |
2017年 | 23篇 |
2016年 | 16篇 |
2015年 | 11篇 |
2014年 | 23篇 |
2013年 | 45篇 |
2012年 | 52篇 |
2011年 | 47篇 |
2010年 | 32篇 |
2009年 | 25篇 |
2008年 | 41篇 |
2007年 | 44篇 |
2006年 | 45篇 |
2005年 | 42篇 |
2004年 | 46篇 |
2003年 | 28篇 |
2002年 | 46篇 |
2001年 | 27篇 |
2000年 | 37篇 |
1999年 | 27篇 |
1998年 | 20篇 |
1997年 | 19篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1994年 | 12篇 |
1992年 | 24篇 |
1991年 | 17篇 |
1990年 | 18篇 |
1989年 | 21篇 |
1988年 | 12篇 |
1987年 | 17篇 |
1986年 | 9篇 |
1985年 | 26篇 |
1984年 | 9篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1979年 | 20篇 |
1978年 | 11篇 |
1977年 | 11篇 |
1974年 | 9篇 |
1973年 | 9篇 |
1972年 | 20篇 |
1971年 | 12篇 |
1970年 | 8篇 |
1968年 | 12篇 |
1967年 | 8篇 |
排序方式: 共有1173条查询结果,搜索用时 11 毫秒
1.
Paul N Bennett Leo Breugelmans Anthony Meade Dee Parkhurst 《Journal of renal nutrition》2006,16(1):59-62
OBJECTIVE: To assess the reliability of a nurse-performed nutrition screening tool (NST) for hemodialysis (HD) patients to identify nutritionally at-risk patients. DESIGN: Tool reliability assessment. SETTING AND PARTICIPANTS: The setting was nine non-hospital private (n = 3) and public (n = 6) HD units in Australia (two rural and seven metropolitan). Participants were 112 HD patients. RESULTS: A total of 112 HD patients (male = 65, female = 47) from 9 non-hospital HD units in Australia (seven metropolitan and two rural) were screened with the NST and the outcome of dietitian referral compared with Standard Dietitians Assessment. The mean age of patients was 57.6 years. Overall, the NST showed a sensitivity of 0.84 (range, 0.71 to 0.94; P < .05) and a specificity of 0.9 (range, 0.82 to 0.98; P < .05). The NST was more sensitive (sensitivity, 0.93 [range, 0.87 to 0.99; P < .05]) and was more specific for men (specificity, 0.92 [range, 0.85 to 0.99; P < .05]). Specificity was very strong in metropolitan patients (specificity, 0.94 [range, 0.87 to 1.01; P < .05]). CONCLUSIONS: The tool was more sensitive and specific than the NST previously reported by the same investigators. The tool is particularly specific in that it screens those patients not requiring dietitian intervention. The use of this tool may benefit HD units that do not have on-site or regular dietetic support to prioritize patients needing dietitian intervention. 相似文献
2.
Effect of compressive follower preload on the flexion-extension response of the human lumbar spine. 总被引:5,自引:0,他引:5
Avinash G Patwardhan Robert M Havey Gerard Carandang James Simonds Leonard I Voronov Alexander J Ghanayem Kevin P Meade Thomas M Gavin Odysseas Paxinos 《Journal of orthopaedic research》2003,21(3):540-546
Traditional experimental methods are unable to study the kinematics of whole lumbar spine specimens under physiologic compressive preloads because the spine without active musculature buckles under just 120 N of vertical load. However, the lumbar spine can support a compressive load of physiologic magnitude (up to 1200 N) without collapsing if the load is applied along a follower load path. This study tested the hypothesis that the load-displacement response of the lumbar spine in flexion-extension is affected by the magnitude of the follower preload and the follower preload path. Twenty-one fresh human cadaveric lumbar spines were tested in flexion-extension under increasing compressive follower preload applied along two distinctly different optimized preload paths. The first (neutral) preload path was considered optimum if the specimen underwent the least angular change in its lordosis when the full range of preload (0-1200 N) was applied in its neutral posture. The second (flexed) preload path was optimized for an intermediate specimen posture between neutral and full flexion. A twofold increase in flexion stiffness occurred around the neutral posture as the preload was increased from 0 to 1200 N. The preload magnitude (400 N and larger) significantly affected the range of motion (ROM), with a 25% decrease at 1200 N preload applied along the neutral path. When the preload was applied along a path optimized for an intermediate forward-flexed posture, only a 15% decrease in ROM occurred at 1200 N. The results demonstrate that whole lumbar spine specimens can be subjected to compressive follower preloads of in vivo magnitudes while allowing physiologic mobility under flexion-extension moments. The optimized follower preload provides a method to simulate the resultant vector of the muscles that allow the spine to support physiologic compressive loads induced during flexion-extension activities. 相似文献
3.
Radiographic analysis of selective ligament sectioning at the carpal scaphoid: a cadaver study 总被引:4,自引:0,他引:4
Although scapholunate diastasis with rotatory subluxation of the scaphoid (stage I perilunar instability determined by Mayfield's classification) has been studied by several investigators, the exact contribution of the supporting ligaments is still being defined. We designed and executed an experimental study using six fresh-frozen cadaver specimens to demonstrate the radiographic changes seen on standard and stress wrist radiographs that correlate with the sequential sectioning of the scapholunate stabilizing ligaments. The radioscapho-lunate ligament, the palmar scapholunate interosseous ligament, the dorsal scapholunate interosseous ligament, and the radiocapitate ligament were sectioned sequentially to simulate a progressive wrist injury caused by an extension, intercarpal supination and ulnar deviation force. The results showed significant ligamentous injury must occur before commonly used radiographic limits are exceeded. The lateral scapholunate angle most closely reflected the progressive nature of this injury. 相似文献
4.
The preparation of novel heterocyclic base modified adenosine analogues, the 4-aminopyrrolo[2,3-d]pyridazine nucleosides, is described. Crucial to their successful preparation was the use of the pyrrole glycoside intermediates 3-cyano-2-formyl-1-(2,3,5-tri-O-benzyl-beta-D-ribofuranosyl)pyrrole (11) and 3-cyano-2-formyl-1-(2,3,5-tri-O-benzyl-beta-D-arabinofuranosyl)pyrrole (17). Treatment of 11 and 17 with hydrazine dihydrochloride followed by treatment with boron trichloride provided 4-amino-1-beta-D-ribofuranosylpyrrolo[2,3-d]pyridazine (2) and 4-amino-1-beta-D-arabinofuranosylpyrrolo[2,3-d]pyridazine (3), respectively. 4-Amino-3-bromo-1-beta-D-ribofuranosylpyrrolo[2,3-d]-pyridazine (4) was prepared by a bromination of 4-amino-1-(2,3,5-tri-O-benzyl-beta-D-ribofuranosyl)pyrrolo[2,3-d]pyri daz ine (12) and subsequent removal of the benzyl groups with boron trichloride. Compounds 2-4 were evaluated for antiproliferative and antiviral activity. The tubercidin analogue (2) and its arabinosyl derivative (3) were virtually inactive in all assays. In contrast, the 3-bromo analogue 4 inhibited growth of L1210 and H. Ep. 2 cells. Compound 4 was also active against human cytomegalovirus and herpes simplex virus type 1, but the antiviral activity was not completely separated from cytotoxicity. 相似文献
5.
H C Wilkes T W Meade S Barzegar A J Foley L O Hughes K A Bauer R D Rosenberg G J Miller 《Thrombosis and haemostasis》1992,67(5):503-506
The effects of gemfibrozil on several indices of haemostatic activity were explored in male patients with coronary heart disease (CHD). Sixty-three of 71 patients completed a crossover study in which gemfibrozil 1,200 mg/day and matching placebo were each taken in randomised order for 2 months in a double-blind manner, separated by a 2-month washout period. Serum cholesterol decreased by an average (95% confidence interval) of 12 (9 to 15)% and non-fasting triglyceride concentration by 43 (34 to 51)% during active treatment. Plasma prothrombin fragment F1 + 2 concentration, a marker of the in vivo rate of generation of thrombin, was 25 (12 to 37)% lower on average while on gemfibrozil than during the placebo phase. Factor VII coagulant activity (VIIc) and antigen concentration, and fibrinopeptide A concentration were not influenced by gemfibrozil in the group overall. However, the VIIc response appeared to be dependent upon the untreated cholesterol level. Hypercholesterolaemic men (cholesterol greater than 6.5 mmol/l) experienced a significant reduction in VIIc averaging 6% of standard during active therapy. Other effects of gemfibrozil were a 5 (2 to 9)% increase in plasma fibrinogen by a gravimetric method, an 11 (8 to 13)% increase in platelet count, and a 6 (2 to 10)% reduction in white cell count. The reduced incidence of CHD following gemfibrozil therapy in hyperlipidaemic patients may arise in part through a reduction in procoagulant activity and thus the risk of an occlusive coronary thrombosis. 相似文献
6.
T W Meade 《International journal of cardiology》1992,37(3):424-426
Over a period of 12 years, two cases of pulmonary arterial aneurysms were encountered in our autopsy data of 13 cases of congenital heart defects with right-sided infective endocarditis. Pulmonary arterial aneurysms are rare lesions and may be categorized as central or peripheral. Although early reports implicated tuberculosis as a major aetiologic factor, pulmonary arterial aneurysms are generally associated with congenital heart disease. 相似文献
7.
An assessment of three simple methods of typing Proteus strains is described. The methods chosen were biochemical typing, bacteriocine typing, and typing by means of the Dienes phenomenon. Dienes typing was deemed to be superior to biochemical typing and bacteriocine typing.A brief discussion on the relationship between the Dienes phenomenon and bacteriocine production is appended. 相似文献
8.
C J Meade J Sheena J Mertin 《International archives of allergy and applied immunology》1979,58(2):121-127
Spleen cells from mice homozygous for the obese (ob) mutation killed DBA/2 mastocytoma target cells less well than spleen cells from lean littermates or unrelated age-and sex-matched controls of the same strain. Killing was impaired only when the attacker cells were primed in vivo, not following in vitro priming. Hence the effect of the ob/ob genotype is not to produce an irreversible functional change in the lymphocyte, but rather to produce an environment in which lymphocytes are less able to react to priming antigen. Not only were the spleen cells of in vivo primed obese mice less active than those of lean controls, but also their number per spleen was significantly decreased. Such a quantitive difference was no longer found in adrenalectomised animals, but the qualitative difference in spleen cell cytotoxic activity still occurred. This suggests that adrenocortical hyperfunction may affect immune function in obese mice, without necessarily being the only factor in the in vivo environment of obese mouse spleen cells capable of depressing cellular immune reactivity. 相似文献
9.
Conclusions influencing clinical decisions about the effects of hormone replacement therapy (HRT) on cardiovascular disease have undergone major revisions over the last 30 years. Assumptions in the early 1970s that HRT would increase thromboembolic conditions were reversed in the 1980s, when the first formal studies seemed to indicate a cardioprotective effect. The Heart and Estrogen/progestin Replacement Study (HERS) has, however, very recently suggested that HRT does not affect the incidence of coronary heart disease (CHD) one way or the other. These roller-coaster changes of direction have made decisions by doctors and their patients about the long-term use of HRT extremely difficult and need to be replaced by the stability that only further randomised controlled trials (RCTs) can now provide. 相似文献
10.