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1.
G Reishofer F Fazekas S Keeling C Enzinger F Payer J Simbrunner R Stollberger 《Magnetic resonance in medicine》2007,57(2):278-288
The pronounced susceptibility effect of macrovessels in MR bolus-tracking studies induces spots of artificially high blood flow and volume in perfusion parameter images. These high-intensity regions impede the detection of perfusion changes and lead to elevated perfusion parameters in adjacent tissues. The purpose of this work was to explore postprocessing methods to reduce the influence of macrovessel signal in dynamic MRI. After data reduction was performed with the use of a principal component analysis (PCA), an independent component analysis (ICA) was applied to separate signal components of different compartments. Based on this decomposition, the dynamic time series were reconstructed with minimized contributions of macrovessel signal and noise. The influence of the temporal resolution and signal-to-noise ratio (SNR) of the source data were investigated by means of a simulation study. A region-of-interest (ROI)-based analysis of corrected and uncorrected in vivo data demonstrated that the influence of arteries and veins was reduced at least by 50%, while gray matter (GM) and white matter (WM) tissues were nearly unaffected by the correction process. Hemodynamic parameter images of the cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) were calculated from corrected and uncorrected scans. The corrected parameter images showed a clearly reduced macrovessel signal and an improved perceptibility of microvascular perfusion changes compared to the uncorrected ones. 相似文献
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3.
J W Babich F Keeling M A Flower L Repetto A Whitton S Fielding A Fullbrook R J Ott V R McCready 《European journal of nuclear medicine》1988,14(1):39-44
A preliminary study of the distribution of the 99mTc complex of hexamethylpropylene amine oxime (HM-PAO) in 12 patients with brain neoplasms before, during, and after radiotherapy has been performed. Untreated brain tumors were found to exhibit a range of 99mTc-HM-PAO uptake, varying from areas of markedly increased isotope activity to photopenic areas, when compared to normal brain tissue. A ratio of 99mTc-HM-PAO tumor uptake to contralateral normal tissue uptake was calculated prior to and during radiotherapy. This ratio tended to return towards unity in lesions responding to therapy. A predictable alteration in whole brain 99mTc-HM-PAO uptake during radiotherapy was not demonstrated. Unlike the radiolabeled amines, 99mTc-HM-PAO localizes in primary tumors, probably indicating that its uptake mechanism is independent of non specific amine receptors. 99mTc-HM-PAO may be useful in the study of brain tumor physiology and response to therapy. 相似文献
4.
Seventy-nine patients with primary hyperparathyroidism, whose average preoperative blood calcium level was 11.6 mg/dl, underwent thallium-technetium dual isotope scintigraphy of the thyroid and parathyroids. For patients who had surgery, the detection and localization rate of parathyroid disease or the sensitivity was low (0.53), but the positive predictive value for the location was high (0.80). Correct localization correlated positively with the weight of the tumor but not significantly with the parathyroid hormone blood level nor with the blood calcium level. Unprocessed data alone were sufficient to predict correctly the location in two thirds of the detected cases. Computer processing increased the sensitivity without decreasing the specificity. Those results, at variance with earlier published data but congruent with another more recent study, require a reevaluation of the role of this scintigraphic technique in the management of hyperparathyroidal patients. 相似文献
5.
S. R. Hesslewood D. H. Keeling 《European journal of nuclear medicine and molecular imaging》1997,24(9):1179-1182
A prospective survey was performed in 17 nuclear medicine departments during 1996 in an attempt to provide reliable data on the prevalence of adverse reactions to radiopharmaceuticals. All adverse events following radiopharmaceutical administration were recorded, irrespective of the severity or likelihood of causality, and subsequently analysed using an algorithm developed by Silberstein et al., designed to establish a cause-effect relationship. A prevalence of 11 events per 105 administrations was obtained (95% confidence limits 3.3–19.2). No serious of life-threatening events were reported. This rate is slightly higher than that obtained in a larger scale study in the United States (2.3 events per 105 administrations, 95% confidence limits 1.2–3.4). The difference may be due to the decision to include or exclude vasovagal events from the analysis, the way in which the algorithm was used and the comparative size and time scale of the two studies. The prevalence of adverse reactions is approximately 1000-fold than less that occurring with iodinated contrast media and drugs. 相似文献
6.
Phaeohyphomycotic cutaneous disease caused by Pleurophoma in a cardiac transplant patient 总被引:2,自引:0,他引:2
D P Dooley M L Beckius B S Jeffery C K McAllister W H Radentz A R Feldman M G Rinaldi S R Bailey J H Keeling 《The Journal of infectious diseases》1989,159(3):503-507
A 56-y-old female cardiac transplant patient treated with cyclosporine and prednisone noted the onset of three nontender red nodules on the legs and arms after gardening. Biopsy of all lesions revealed inflammatory cells and hyphal elements in the dermis. The dematiaceous fungus cultured from biopsy tissue was a pycnidial-forming organism of the genus Pleurophoma. The lesions responded to the topical application of miconazole. 相似文献
7.
Experimental columnar metaplasia in the canine oesophagus 总被引:7,自引:0,他引:7
P Gillen P Keeling P J Byrne A B West T P Hennessy 《The British journal of surgery》1988,75(2):113-115
Regeneration of canine oesophageal mucosa was studied under basal conditions and in the presence of gastro-oesophageal reflux. In normal circumstances mucosal defects in the oesophagus regenerate by squamous epithelium. In the presence of gastro-oesophageal reflux of either acid or a combination of acid and bile, regeneration was frequently by columnar epithelium (Barrett's oesophagus). This columnar regeneration was not seen with bile reflux alone. By the use of squamous barriers to proximal migration of columnar epithelium in the stomach, it was demonstrated that columnar re-epithelialization may occur from cells intrinsic to the oesophagus and is not dependent on proximal migration of cardiac columnar epithelium. The cell of origin of this epithelium may be located in oesophageal gland ducts and is likely to be a multipotential stem cell since the regenerated columnar epithelium may contain goblet and parietal cells not normally found in the oesophagus. This epithelium is morphologically distinct on mucin histochemistry from cardiac columnar epithelium. These findings support the concept that Barrett's epithelium is metaplastic. 相似文献
8.
B A Gould J Turner D H Keeling P Hickling A J Marshall 《Annals of the rheumatic diseases》1992,51(2):227-232
Echocardiographic evidence has suggested abnormalities of the myocardial function in patients with ankylosing spondylitis. In this work the cardiac function in patients with ankylosing spondylitis and in normal volunteers was evaluated. Twenty four normal volunteers and 21 patients with ankylosing spondylitis aged 18-45 were studied. None had overt cardiac disease. Cardiac function was assessed at rest with echocardiography, at rest and during supine bicycle exercise using radionuclide angiography in the left anterior oblique position following equilibration with 740 MBq of technetium-99. The subjects undertook supine bicycle exercise with 30 W increments every three minutes to the point of fatigue. Comparison of data from normal volunteers and patients with ankylosing spondylitis were made using Student's t test for independent samples or the Mann-Whitney non-parametric technique, as appropriate. Subjects were matched for age, sex, height, and weight. There were no echocardiographic differences; however, global nuclide left ventricular function showed several differences between normal volunteers and patients with ankylosing spondylitis. The peak filling rate during exercise was significantly lower in patients with ankylosing spondylitis: normal volunteers 6.5 (SD 1.2); patients with ankylosing spondylitis 5.7 (1.2). The time to reach peak filling during exercise was significantly lower in patients with ankylosing spondylitis: normal volunteers 102 (22); patients with ankylosing spondylitis 120 (23). Regional analysis also showed differences between patients with ankylosing spondylitis and normal volunteers both at rest and during exercise. In the anteroseptal region the filling fraction and peak filling rate were significantly lower in patients with ankylosing spondylitis. Most of the differences (although not all) were in the variables of diastolic function. This study shows that there are subtle abnormalities in cardiac function in patients with ankylosing spondylitis. The major abnormalities are in the diastolic function, suggesting a decrease in left ventricular compliance. 相似文献
9.
R J Ife T H Brown D J Keeling C A Leach M L Meeson M E Parsons D R Reavill C J Theobald K J Wiggall 《Journal of medicinal chemistry》1992,35(18):3413-3422
Previously, gastric (H+/K+)-ATPase inhibitors such as 2 have been prepared as analogues of 1a on the presumption that the 3-carbethoxy substituent plays a key role in establishing the orientation of the 4-arylamino group. In this paper we explore further the contribution made to activity by the quinoline 3-substituent. We show that, for compounds bearing such a substituent, only a particular combination of properties provides high activity, both in vitro and as inhibitors of gastric acid secretion in vivo. The ability of the substituent to affect activity by restricting rotation about the Cquin-N bond through a combination of both a pi-electron withdrawal and hydrogen bonding is supported by the current study. However, high activity is only achieved if the effect of this group on the quinoline pK(a) is kept to a minimum. 3-Acyl substituents provide an optimum combination of electronic properties. From this series, compound 17c (SK&F 96067) was shown to be a potent inhibitor of histamine-stimulated gastric acid secretion after oral dosing in the Heidenhain pouch dog and was selected for further development and evaluation in man. 相似文献
10.