全文获取类型
收费全文 | 18680篇 |
免费 | 1976篇 |
国内免费 | 16篇 |
专业分类
耳鼻咽喉 | 151篇 |
儿科学 | 632篇 |
妇产科学 | 649篇 |
基础医学 | 2616篇 |
口腔科学 | 356篇 |
临床医学 | 2188篇 |
内科学 | 3781篇 |
皮肤病学 | 192篇 |
神经病学 | 1438篇 |
特种医学 | 523篇 |
外科学 | 2642篇 |
综合类 | 565篇 |
一般理论 | 43篇 |
预防医学 | 2307篇 |
眼科学 | 297篇 |
药学 | 1371篇 |
中国医学 | 15篇 |
肿瘤学 | 906篇 |
出版年
2021年 | 315篇 |
2020年 | 199篇 |
2019年 | 301篇 |
2018年 | 335篇 |
2017年 | 272篇 |
2016年 | 244篇 |
2015年 | 280篇 |
2014年 | 410篇 |
2013年 | 625篇 |
2012年 | 842篇 |
2011年 | 953篇 |
2010年 | 495篇 |
2009年 | 470篇 |
2008年 | 777篇 |
2007年 | 823篇 |
2006年 | 759篇 |
2005年 | 798篇 |
2004年 | 721篇 |
2003年 | 712篇 |
2002年 | 670篇 |
2001年 | 597篇 |
2000年 | 636篇 |
1999年 | 545篇 |
1998年 | 246篇 |
1997年 | 204篇 |
1996年 | 223篇 |
1995年 | 201篇 |
1994年 | 164篇 |
1993年 | 157篇 |
1992年 | 433篇 |
1991年 | 476篇 |
1990年 | 442篇 |
1989年 | 406篇 |
1988年 | 351篇 |
1987年 | 381篇 |
1986年 | 350篇 |
1985年 | 337篇 |
1984年 | 283篇 |
1983年 | 238篇 |
1982年 | 150篇 |
1981年 | 142篇 |
1979年 | 192篇 |
1978年 | 145篇 |
1977年 | 148篇 |
1976年 | 122篇 |
1974年 | 182篇 |
1973年 | 163篇 |
1972年 | 131篇 |
1971年 | 115篇 |
1970年 | 133篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
One hundred patients with cirrhosis underwent abdominal computed tomography (CT) using a delayed contrast technique to determine liver and spleen volume. These scans were reviewed to screen this "at risk" population for hepatocellular carcinoma (HCC). Fifteen of the 100 screened patients had focal abnormalities suspicious for HCC. On biopsy, only 1 patient was shown to have HCC. The other 14 patients had either fatty infiltration or focal regeneration. In the same time interval, a total of 10 patients had histologically proven HCC. All presented with symptoms and died within 4 months of diagnosis. The results show that focal hepatic lesions can be detected by CT but in this population the lesions may not be due to HCC. The incidence of HCC was approximately 1%, probably reflecting a truly low incidence in this population. 相似文献
102.
Petit mal-grand mal (PM-GM) electroconvulsive therapy (ECT) is a technique developed by Impastato to elicit unconsciousness with a subconvulsive electrical stimulus, rather than with barbiturate anesthesia. Muscle relaxation is produced with succinylcholine chloride before stimulus is applied. The cases reported here illustrate applications of the technique to depressed patients with severe cardiac and pulmonary disease, and the use of PM-GM ECT in a patient in whom seizures could not be elicited by the usual ECT technique is described. 相似文献
103.
Developing rats are far more sensitive than adults to the behavioral effects of haloperidol. The present results support the hypothesis that this change may reflect age-related changes in brain responses such as alterations in drug-receptor or drug-effector mechanisms. Dose-response studies of catalepsy and ptosis were conducted in male Sprague-Dawley rats aged 30, 56, or 100 days. Resulting dose-effect curves were approximately parallel and showed rightward shifts with highly significant progressive increases of ED50. Similar developmental decreases in drug sensitivity (3–6 ×) were found following systemic (PO or IP) administration of haloperidol or the phenothiazine neuroleptic perphenazine, which differ markedly in structure, potency, distribution, and metabolism. Age-related decreases in drug sensitivity (3–4 ×) were also found using intracerebroventricular (ICV) administration of both agents in an attempt to bypass potential pharmacokinetic influences. Since the age-dependent decrease in sensitivity to both neuroleptics was found during the rising phase of drug action (1st hour) and ranked: PO>IP>ICV, some change in absorption and distribution of both drugs may occur in addition to the apparently important maturational decrease in target-organ sensitivity indicated by the responses to direct ICV injection and by the similarity of results obtained with dissimilar agents. 相似文献
104.
BACKGROUND: Transportation of critically ill, mechanically ventilated patients from intensive care units for diagnostic and therapeutic procedures has become common in the last decade. Maintenance of adequate oxygenation and ventilation during transport is essential. We evaluated the Impact Uni-Vent 750 portable ventilator in the laboratory and in the clinical arena to determine its usefulness during inhospital transport. MATERIALS & METHODS: In the laboratory, we determined the Uni-Vent 750's ability to assure tidal volume (VT) delivery in the face of decreasing compliance of a test lung and tested the alarm systems. Using a two-compartment lung model modified to simulate spontaneous breathing, we also evaluated the responsiveness of the demand valve. The clinical evaluation was accomplished by comparing arterial blood gas values and ventilator settings in the intensive care unit before transport to those during transport. RESULTS: As lung compliance was reduced from 0.1 to 0.02 mL/cm H2O [1.0 to 0.20 L/kPa], a slight, statistically insignificant decrease in delivered tidal volume was observed. All alarm systems operated according to manufacturer's specifications. The demand valve triggered appropriately with PEEP from 0 to 20 cm H2O [0 to 1.96 kPa]. Sensitivity settings less than -6 cm H2O [-0.59 kPa] sometimes resulted in inability to trigger the demand valve. During patient transport, arterial blood gas values and ventilator settings were comparable to those observed in the ICU. Because an FIO2 of 1.0 was used during transport, mean (SD) PaO2 was significantly greater 89 (26) vs 341 (78) [11.8 (3.5) vs 45.3 (10.4) kPa]. CONCLUSIONS: The Uni-Vent 750 is a reliable transport ventilator, capable of maintaining adequate oxygenation and ventilation in a majority of mechanically ventilated patients. The Uni-Vent 750's ability to (1) provide CMV, AMV, and SIMV; (2) provide low and high pressure alarms; and (3) provide PEEP compensation is unique among portable ventilators. 相似文献
105.
The purpose of this paper is to review the therapeutic applications of electrical stimulation and to focus on functional neuromuscular electrical stimulation (FES), which is the production of useful muscle contractions for joint stability and limb movement. The use of FES to improve patient function during the recovery period after illness or injury and the transition to FES neural prosthetic systems for patients who do not fully recover will be discussed. Emphasis will be given to the maintenance of posture and the production of purposeful movement from the perspective of technologies and clinical strategies that are available today and from the perspective of those technologies that have the potential for transfer to community health care in the near future. 相似文献
106.
Blood platelet uptake of serotonin in episodic aggression 总被引:2,自引:0,他引:2
C S Brown T A Kent S G Bryant R M Gevedon J L Campbell A R Felthous E S Barratt R M Rose 《Psychiatry research》1989,27(1):5-12
Blood platelet uptake of 3H-serotonin (5HT uptake), a potential marker of serotonergic function, was determined in male outpatients with episodic aggression (n = 15) and in age- and sex-matched nonaggressive controls (n = 15). Correlations with rating scales of "impulsivity" (Barratt Impulsivity Scale, 10th revision) and "anger" (Spielberger Anger Expression Scale) were performed. Mean 5HT uptake was 18% lower in patients with episodic aggression. A significant negative correlation between % difference in platelet 5HT uptake and impulsivity score was observed, but the correlation between 5HT uptake and anger was not significant. These results support the hypothesis of disturbed serotonergic function in aggression and suggest that the primary relationship is in the "control" of aggression. The blood platelet may be useful in identifying impulsive subtypes. 相似文献
107.
Detection of clustered gastrointestinal contractions in partial intestinal obstruction by surface vibration analysis. 下载免费PDF全文
Gastrointestinal contraction "clusters" with alternating quiescence occur in partial intestinal obstruction and are conventionally detected by intraluminal manometry. Surface Vibration Analysis (SVA), which is a noninvasive test, was evaluated in this study in experimental and clinical situations. In the experimental situation, former SVA was assessed against simultaneous manometry in two volunteers, in whom partial obstruction had been induced by intrajejunal balloon distension. Manometry showed typical contraction "clusters" with alternating quiescence, each of two to four minutes duration, in obstructed jejunum proximal to the balloon. The distal jejunum was inhibited. SVA showed a pattern of hyperactivity and quiescence corresponding to proximal jejunal activity. In the clinical situation, SVA recordings taken after a standard meal in nine patients with suspected chronic obstruction adhesive obstruction, (subsequently proven in seven patients and disproved in two), and 36 volunteers were compared. All patients with proved obstruction showed an SVA pattern of alternating hyperactivity and quiescence. This pattern was not observed in volunteers or nonobstructed patients. 相似文献
108.
Inhibition of allergic airways inflammation and airway hyperresponsiveness in mice by dexamethasone: role of eosinophils,IL-5, eotaxin,and IL-13 总被引:4,自引:0,他引:4
Eum SY Maghni K Hamid Q Eidelman DH Campbell H Isogai S Martin JG 《The Journal of allergy and clinical immunology》2003,111(5):1049-1061
BACKGROUND: Glucocorticoids inhibit allergen-induced airway eosinophilia and airway hyperresponsiveness (AHR). Whether glucocorticoids mediate their effects on AHR by inhibiting eotaxin and IL-5, 2 of the principal mediators of eosinophilia, or through IL-13, an important mediator of AHR, has not been established. OBJECTIVE: We sought to investigate the effects of glucocorticoids on airway eosinophilia and the expression of IL-5, eotaxin, and IL-13 in relation to the induction of AHR in a murine model of allergic asthma. METHODS: Dexamethasone (4 mg/kg) and mAbs against eotaxin (80 micro g/kg) and IL-5 (100 micro g/kg) singly and in combination were administered to immunized mice before antigen challenge. Airway responsiveness to methacholine was measured in anesthetized and mechanically ventilated animals. Eotaxin, IL-5, and IL-13 in bronchoalveolar lavage fluid (BALF), lung homogenates, or both were measured by means of ELISA. RESULTS: A single antigen challenge induced AHR that lasted at least 10 days. Eotaxin protein and mRNA levels increased in lung tissue but not in BALF after challenge. IL-5 protein and mRNA levels increased both in BALF and in lung tissue. Dexamethasone reduced airway eosinophilia, AHR, and protein and mRNA for eotaxin and IL-5. Anti-murine eotaxin and anti-IL-5 antibodies alone and in combination reduced the ovalbumin-induced airway eosinophilia significantly but failed to inhibit AHR. Both dexa-methasone and anti-IL-5/anti-eotaxin inhibited the increases in lung IL-13 levels after ovalbumin challenge to a similar extent. CONCLUSION: These findings suggest that the inhibition of AHR by the glucocorticoid dexamethasone does not appear to be explained by effects on eosinophilia, eotaxin, IL-5, or IL-13. 相似文献
109.
The present study investigated the duration of afterdepolarizations in Purkinje cell somata following climbing-fibre activation. Intracellular recordings revealed that, in cells with membrane potentials more negative than -50 mV and with normal spike-generating capabilities, climbing-fibre activation resulted in somatic responses with short afterdepolarizations. As the cell deteriorated and the resting membrane potential became more positive, the duration and form of the climbing-fibre response resembled the plateau potentials recorded from proximal dendrites. The absence of plateau potentials in undamaged Purkinje cell somata was confirmed by extracellular recording of test spike amplitudes following evoked climbing-fibre responses. 相似文献
110.
Gilbert TH Corley SM Teskey GC 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2002,146(3):336-344
This study addressed the anticonvulsant effects of phenobarbital, valproate, and ethosuximide in the amygdala of kindled guinea pigs to further validate this model for the screening of anticonvulsant drugs. Behavioral toxic effects were assessed at 30 min following drug administration using quantitative locomotor tests, as well as scores on a sedation and muscle relaxation rating index. The anticonvulsant efficacy of the drugs were evaluated from measurements of afterdischarge threshold (ADT), afterdischarge duration (ADD), and behavioral seizure severity (SS) during early and late phases of kindling acquisition, and in kindled guinea pigs. ADD and SS were also measured in response to both threshold and suprathreshold kindling stimulation. All drugs exerted slight to moderate sedative effects in guinea pigs on both the behavioral tests and rating index. We found that phenobarbital exhibited effective anticonvulsant properties in guinea pigs by consistently reducing ADD and SS in response to both threshold and suprathreshold kindling stimulation. Valproate exhibited effective anticonvulsant properties at threshold stimulation and less effective properties at suprathreshold stimulation. Lastly, we found that ethosuximide lacked effective anticonvulsant action at either threshold or suprathreshold kindling stimulation. Our results indicate that the guinea pig kindling model correctly predicted the actions of phenobarbital, valproate, and ethosuximide in the treatment of partial seizures. Guinea pig amygdala kindling appears to serve as a useful and valid model for partial epilepsy. 相似文献