全文获取类型
收费全文 | 8941篇 |
免费 | 580篇 |
国内免费 | 58篇 |
专业分类
耳鼻咽喉 | 53篇 |
儿科学 | 224篇 |
妇产科学 | 257篇 |
基础医学 | 1381篇 |
口腔科学 | 278篇 |
临床医学 | 806篇 |
内科学 | 1836篇 |
皮肤病学 | 139篇 |
神经病学 | 869篇 |
特种医学 | 349篇 |
外国民族医学 | 1篇 |
外科学 | 1267篇 |
综合类 | 85篇 |
一般理论 | 12篇 |
预防医学 | 646篇 |
眼科学 | 175篇 |
药学 | 607篇 |
中国医学 | 4篇 |
肿瘤学 | 590篇 |
出版年
2023年 | 51篇 |
2022年 | 79篇 |
2021年 | 165篇 |
2020年 | 93篇 |
2019年 | 176篇 |
2018年 | 224篇 |
2017年 | 137篇 |
2016年 | 162篇 |
2015年 | 203篇 |
2014年 | 306篇 |
2013年 | 402篇 |
2012年 | 516篇 |
2011年 | 567篇 |
2010年 | 317篇 |
2009年 | 262篇 |
2008年 | 511篇 |
2007年 | 530篇 |
2006年 | 491篇 |
2005年 | 451篇 |
2004年 | 509篇 |
2003年 | 446篇 |
2002年 | 416篇 |
2001年 | 144篇 |
2000年 | 155篇 |
1999年 | 163篇 |
1998年 | 107篇 |
1997年 | 65篇 |
1996年 | 72篇 |
1995年 | 72篇 |
1994年 | 60篇 |
1993年 | 42篇 |
1992年 | 69篇 |
1991年 | 53篇 |
1990年 | 56篇 |
1989年 | 57篇 |
1988年 | 58篇 |
1987年 | 47篇 |
1986年 | 72篇 |
1985年 | 59篇 |
1984年 | 62篇 |
1983年 | 55篇 |
1982年 | 49篇 |
1981年 | 42篇 |
1980年 | 38篇 |
1979年 | 33篇 |
1978年 | 40篇 |
1977年 | 38篇 |
1975年 | 29篇 |
1973年 | 37篇 |
1971年 | 25篇 |
排序方式: 共有9579条查询结果,搜索用时 78 毫秒
91.
Anselmo M De Leo P Rosone A Minetti F Cutillo A Vaira C Menardo G 《Le infezioni in medicina : rivista periodica di eziologia, epidemiologia, diagnostica, clinica e terapia delle patologie infettive》1996,4(1):45-47
A case of unusual transmission by Plasmodium falciparum malaria is reported. The patient, had not been travelling outside North-West of Italy for the previous 6 months, he was not drug abuser. He had spent the last two months prior his admission, partly in his home town, an urban area in the region of Piemonte, and partly in a resort area on the Ligurian sea. Neither place has ever been associated with unusual malaria transmission. The possible transmission way is through a live vector imported from endemic area in a port terminal near a resort area. 相似文献
92.
Marc J. Claeys Frank E. Rademakers Chris J. Vrints Bruno Krug Johan M. Bosmans Viviane Conraads Leo L. Bossaert Jo P. Snoeck Pierre P. Blockx 《European journal of nuclear medicine and molecular imaging》1996,23(7):748-755
Rest technetium-99m sestamibi single-photon emission tomography (SPET) has been shown to under-estimate viability in some patients with chronic ischaemic myocardial dysfunction. The present study was designed to appraise the value of99mTc-sestamibi as a viability tracer in patients with a recent myocardial infarction and to determine factors that might influence its accuracy in assessing infarct size. Therefore, rest99mTc-sestamibi SPET, low-dose dobutamines stress echocardiography and quantitative coronary angiography were performed in 51 patients with a recent myocardial infarction. Perfusion activity and regional wall motion were scored semi-quantitatively using the same segmental division of the left ventricle. Assessment of99mTc-sestamibi uptake as a marker of viability was performed by comparing a binary uptake score (viable=>50% vs necrotic =50% of the maximal tracer activity) with a binary wall motion classification during low-dose dobutamine infusion (viable=normal/hypokinetic vs necrotic=akinetic/dyskinetic). Infarct size, expressed as the number of segments with evidence of necrotic tissue, was significantly greater in the scintigraphic study than in the echocardiographic study (2.8±1.5 vs 2.2±1.3,P=0.006). This overestimation of infarct size by99mTc-sestamibi was present only in patients with a severe infarct-related stenosis (% diameter stenosis 65%–100%) and particularly those with late reperfusion therapy (time delay 180 min). In patients without a severe infarct-related stenosis,99mTc-sestamibi was able to accurately distinguish viable from necrotic segments. Thus, rest99mTc-sestamibi scintigraphy early after acute myocardial infarction may underestimate residual viability within the infarct region, particularly in patients with low flow state coronary anatomy, as a result of a severe infarct-related stenosis and/or late reperfusion therapy.This paper was presented in part at the European Nuclear Medicine Congress, Brussels, Belgium, August 1995 相似文献
93.
Lipids in the pulmonary circulation were determined biochemically and histologically in seven patients (group A) who died following multiple blunt trauma and in five patients (group B) who died of some other traumatic or nontraumatic cause. Autopsy was performed on average 4.5 hours after death. Blood samples were collected from the right ventricle (RV) and the left atrium (LA). The vasculature of the left lung was perfused in a retrograde direction. The inferior lobe of the right non-perfused lung was examined histologically. Intravascular pulmonary fat was observed in 4/6 cases in group A and in 1/5 cases in group B. No intravascular fat was observed in the tissue samples of brain, liver or kidney. The concentration of free fatty acids (FFA) in blood from RV was higher than in blood from LA both in group A (P is less than 0.01) and in group B (P is less than 0.05). The considerable difference in concentrations of FFA between RV and LA and the low concentration of FFA in the lung perfusate may be due to some kind of "fixation" of FFA in the lung tissue, possibly connected with the aetiological factors of the fat embolism syndrome (FES). 相似文献
94.
R. A. Lahti D. L. Evans L. M. Figur R. M. Huff M. W. Moon 《Naunyn-Schmiedeberg's archives of pharmacology》1991,344(5):509-513
Summary The biochemical, endocrine, receptor binding, and behavioral effects of the putative dopamine autoreceptor agonist, U-86170F, were evaluated in various in vivo and in vitro models. U-86170F and apomorphine were shown to cause a significant reversal of the effects of -butyrolactone (GBL) on dopamine accumulation in mouse striata. In contrast to apomorphine, U-86170F had a ceiling effect on the extent of the reversal of GBL effects (55%), whereas apomorphine had an 82% reversal. The effect on striatal homovanillic acid (HVA) levels was also monitored, and both compounds exerted a similar and significant reduction in striatal HVA. A comparison was made between the effects of intraperitoneal (i.p.) and oral administration of U-86170F in the -methyl-p-tyrosine (-MPT)/prolactin model in rats. When administered by the i.p. route, U-86170F suppressed the effects of -MPT on prolactin level increase, having an ED50 of about 0.03 mg/kg, and when administered by the oral route, its ED50 was approximately 0.1 mg/kg. U-86170F has been shown to be a potent dopamine autoreceptor agonist in the GBL, prolactin, and HVA models, with an effective i.p. dose of approximately 0.03 mg/kg. When evaluated for postsynaptic dopaminergic activity in the reserpinized mouse model, and compared to apomorphine, U-86170F was found to increase locomotor activity, but its maximum effect was only 65% of that attained with apomorphine. Higher doses were needed for postsynaptic effects.In receptor binding studies using cloned D2 receptor preparations, U-86170F was found to exhibit agonist binding properties similar to dopamine as demonstrated by their inhibition of 3H-raclopride binding. Both compounds exhibited biphasic inhibition curves, with U-86170F having Ki values of 7.5 nM and 250 nM, and for dopamine the Ki values were 34.7 nM and 1031 nM. Binding studies conducted in the presence of GTP yielded only one site with Kis of 289 nM and 670 nM, for both U-86170F and dopamine, respectively.The results presented in this report demonstrated that U-86170F is a potent dopamine autoreceptor agonist, with limited activity at the postsynaptic receptor.
Send offprint requests to R.A. Lahti at the above address 相似文献
95.
Gu Leo C. Erdös Elizabeth A. Chiang Hi-Shi Calderwood Thomas Tsai Kelly Visor Gary C. Duffy Jane Hsu Wen.-C. Foster Linda C. 《Pharmaceutical research》1991,8(4):485-490
The thermal stability of IL-1 in aqueous solution as a function of temperature (5–60°C), pH (2–9), buffer (acetate, citrate, tris, and phosphate), and cyroprotectants (sugars, HSA) was investigated in this study. The analytical methodologies included RP-HPLC, SEC, ELISA, IEF-PAGE, SDS-PAGE, and bioassay. The degradation and inactivation of IL-1 at or above 39°C were attributed to autoxidation of the two cysteine residues in the denatured protein, followed by hydrophobic/covalent aggregation and precipitation. At or below 30°C, IEF- and SDS-PAGE results suggest a possible deamidation reaction. The difference in mechanism of degradation precludes the prediction of formulation shelf life from accelerated temperature data. Nonetheless, the good stability observed at 5°C suggests that a solution formulation may be feasible for IL-1. 相似文献
96.
D. De Leo R. Rozzini M. Bernardini M. Zucchetto R. Gallato A. Villa M. Dello Buono F. Grigoletto M. Trabucchi 《Quality of life research》1992,1(6):367-374
This study evaluates the effects of a Tele-check/Tele-emergency service on the quality of life in the elderly. Through telephone interviews a questionnaire has been repeatedly administered to explore various psychological, somatic, and social aspects in a random sample of 574 subjects aged 65 years and over (mean = 76.8 years). The findings suggest that the elderly helped by the service (in its control functioning) make less demands on health facilities (GPs visits, number of days in hospital) as compared to controls. Implications are presented and discussed. 相似文献
97.
E Chartier-Kastler F Richard B Truchot J P Leo A Perrot A Jardin C Chatelain 《Annales d'Urologie》1992,26(1):49-52
Urethral diverticulum in women is not a frequent disease. The diagnosis of this lesion is based on history and careful physical examination looking for a swelling on the anterior vaginal wall. A study of 15 cases is reported. The authors insist on investigations as a help to confirm and localise the diverticulum. A new technique of retrograde urethrography using a prehension cannula ("Bomelaer") is described. By this well tolerated and minimally invasive test, the visualisation of the urethral diverticulum was obtained in 14/15 patients. Associated with intravenous urography, it is certainly the most adapted strategy for diagnosis and management. 相似文献
98.
Reactivation of electric eel acetylcholinesterase (AChE) inhibited by MeO(NH2)P(O)SMe (methamidophos) and by MeS(NH2)P(O)SMe was studied at pH 7.5 and 25° C. The former inhibited enzyme shows a rather rapid spontaneous reactivation (t1/2=3.7 h); this reactivation is accelerated by 1 M of the bispyridinium oximes TMB4 and obidoxime, and, to a lesser extent, by the monopyridinium oximes P2S and its 1-benzyl analogue (benzyl-P2A). The latter inhibited enzyme shows rapid aging (t1/2=0.6 h). Reactivation with 1 mM of the bispyridinium oximes is incomplete and reactivation with 1 mM of the monopyridinium oximes proceeds very slowly. These large differences between the properties of the two inhibited enzymes indicate that the methylthio group is the leaving group during inhibition of AChE by methamidophos. Additional support is afforded by the observation of induced aging of the former inhibited enzyme by thiourea.Upon comparison of the reactivation of AChE inhibited by methamidophos with that of AChE inhibited by an N-methyl analogue, cruf ornate, and an N,N-dimethyl analogue, tabun, it appears that the rate of spontaneous reactivation decreases with increasing alkylation of the P-NH2 group. Whereas benzyl-P2A is somewhat less active than P2S for reactivation of AChE inhibited by methamidophos, it is superior to P2S for reactivation of AChE inhibited by crufomate and also superior to P2S and to the bispyridinium oximes for AChE inhibited by tabun. 相似文献
99.
Jan-Erik Lindgren Agneta Ohlsson Stig Agurell Leo Hollister Hamp Gillespie 《Psychopharmacology》1981,74(3):208-212
9-Tetrahydrocannabinol (9-THC) was administered in a crossover design by smoking and IV injection to groups of heavy and light users of marihuana. Plasma concentrations of 9-THC were similar for the groups after IV injection of 5.0 mg 9-THC, but the AUC0–240 min showed a trend towards lower values for the heavy user group. To achieve a maximum desired high, both groups smoked similar amounts (about 13 mg) of 9-THC. Heavy users tended to have higher plasma levels than light users. The systemic availability of smoked 9-THC was significantly higher for the heavy users (heavy users 23±16% vs 10±7% for light users). These results also indicate that heavy cannabis users smoke more efficiently than casual smokers.Both light and heavy users showed more clinical effect following IV administration than after smoking. The response of the heavy users, both with respect to effect on heart and high, was quite comparable to that of light users.The present study does not suggest that tolerance readily develops in heavy users. 相似文献
100.
Holcomb HH Lahti AC Medoff DR Weiler M Dannals RF Tamminga CA 《The American journal of psychiatry》2000,157(10):1634-1645
OBJECTIVE: The biological characteristics of schizophrenia are often studied by using functional imaging techniques. However, since volunteers with schizophrenia routinely fail to perform as accurately or as quickly as healthy volunteers, it is difficult to ascertain whether a particular deficit in blood flow to a brain region is due to behavior or to the underlying illness. In this report, investigators used an auditory recognition task to assess brain blood flow patterns and behavioral correlates of schizophrenic patient volunteers trained on the task. METHOD: Twelve healthy volunteers and 18 volunteers with schizophrenia were trained to make tone frequency recognitions. Accuracy and stimuli were matched between groups. Participants were required to press a button to indicate whether a briefly presented tone was the high-frequency (1500 Hz) reference tone or one of a lower frequency level (level chosen to elicit an 80% accuracy score). Subjects underwent bolus [(15)O]H(2)O blood flow positron emission tomography during inactive rest, a sensory motor control condition, and the decision task. Blood flow patterns were assessed between conditions and between groups. RESULTS: As a group, the patients with schizophrenia (who performed as quickly and accurately as the comparison subjects) exhibited significantly less change in regional cerebral blood flow (rCBF) to the anterior cingulate and supplementary motor cortices when switching from the sensory motor control to the decision condition. There were also marked between-group differences in correlations between rCBF and response time. Whereas the comparison subjects exhibited progressively greater blood flow to the frontal cortex in association with longer response times, the schizophrenic patients exhibited progressively lower blood flow in conjunction with extended response times. CONCLUSIONS: The failure to appropriately enhance cingulate activity when engaged in a demanding task and the progressive, time-dependent decline in frontal blood flow suggest that patients with schizophrenia are unable to make optimal use of frontocingulate systems when maximally engaged in high-error tasks. 相似文献