全文获取类型
收费全文 | 2731篇 |
免费 | 339篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 30篇 |
儿科学 | 110篇 |
妇产科学 | 130篇 |
基础医学 | 431篇 |
口腔科学 | 68篇 |
临床医学 | 297篇 |
内科学 | 493篇 |
皮肤病学 | 83篇 |
神经病学 | 254篇 |
特种医学 | 85篇 |
外科学 | 270篇 |
综合类 | 36篇 |
一般理论 | 2篇 |
预防医学 | 319篇 |
眼科学 | 69篇 |
药学 | 237篇 |
中国医学 | 4篇 |
肿瘤学 | 155篇 |
出版年
2021年 | 40篇 |
2019年 | 28篇 |
2018年 | 45篇 |
2017年 | 34篇 |
2016年 | 46篇 |
2015年 | 32篇 |
2014年 | 62篇 |
2013年 | 94篇 |
2012年 | 92篇 |
2011年 | 87篇 |
2010年 | 85篇 |
2009年 | 81篇 |
2008年 | 108篇 |
2007年 | 103篇 |
2006年 | 117篇 |
2005年 | 120篇 |
2004年 | 93篇 |
2003年 | 74篇 |
2002年 | 92篇 |
2001年 | 94篇 |
2000年 | 80篇 |
1999年 | 87篇 |
1998年 | 51篇 |
1997年 | 63篇 |
1996年 | 59篇 |
1995年 | 51篇 |
1994年 | 46篇 |
1993年 | 38篇 |
1992年 | 56篇 |
1991年 | 52篇 |
1990年 | 61篇 |
1989年 | 58篇 |
1988年 | 49篇 |
1987年 | 39篇 |
1986年 | 44篇 |
1985年 | 55篇 |
1984年 | 41篇 |
1983年 | 30篇 |
1982年 | 34篇 |
1981年 | 27篇 |
1980年 | 33篇 |
1979年 | 33篇 |
1978年 | 27篇 |
1976年 | 32篇 |
1975年 | 27篇 |
1973年 | 39篇 |
1972年 | 34篇 |
1971年 | 24篇 |
1970年 | 25篇 |
1969年 | 23篇 |
排序方式: 共有3073条查询结果,搜索用时 15 毫秒
1.
The effect of low dose lofepramine in depressed elderly patients in general medical wards. 下载免费PDF全文
R S Tan R J Barlow C Abel S Reddy A J Palmer A E Fletcher C G Nicholl B M Pitt C J Bulpitt 《British journal of clinical pharmacology》1994,37(4):321-324
A double-blind randomised controlled trial of the effect of low dose lofepramine (70 mg once daily) against placebo was carried out on depressed elderly inpatients on general medical wards for the elderly, comparing measures of depression and side-effects between the randomised groups. Patients were identified for the study using the Geriatric Depression Scale (GDS) and the Brief Assessment Schedule Depression Cards (BASDEC). Sixty-three subjects were randomised: 46 patients completed the entire trial of 28 days treatment. BASDEC and GDS were administered on day 8 post-admission, and depressed patients were randomised double-blind to either low dose lofepramine (70 mg daily) (n = 23) or placebo (n = 23). Assessment of changes in depressive states were made using the Montgomery Asberg Depression Rating Scale (MADRS) on days 8, 18 and 36 post-admission. Both groups improved by a similar amount during the trial. Lofepramine tended to be more effective than placebo in those patients who were more depressed (GDS > or = 18). On the other hand, subjects who were less depressed (i.e. GDS < 18) improved more on placebo than lofepramine. Low dose lofepramine may prove useful in moderately or severely depressed patients treated for only 4 weeks. However, low dose lofepramine is not indicated for mild (GDS 15-18) depression. 相似文献
2.
AM Manganoni† C Farisoglio† G Tucci† F Facchetti‡ PG Calzavara Pinton† 《Journal of the European Academy of Dermatology and Venereology》2007,21(10):1333-1336
BACKGROUND: Development of more than one primary melanoma in a patient is a relatively uncommon but well-recognized phenomenon. Its frequency has ranged from 1.2% to 8.2% in several series. This subgroup of patients with multiple primary lesions has not been characterized sufficiently. We report the experience of the Melanoma Unit of University Hospital Spedali Civili of Brescia, Italy. METHOD: Study subjects were drawn from 1240 patients with histologically confirmed melanoma, including melanoma in situ. From this group, multiple melanomas developed in 47 patients (3.79%). Every one of our patients has been taught to perform self-examination of the skin to detect suspicious pigmented lesions. RESULTS: Of the 47 patients described in this study, 38 had two primary melanomas, 7 had three melanomas and 2 had 5 and 10 melanomas, respectively. Mean age at first diagnosis was 46.2 years. The majority of subsequent melanomas (74.5%) were removed within 5 years of the initial operation. Synchronous lesions were found in 10 patients. In male patients, the lesion appeared most frequently on the trunk; in female patients, melanoma appeared mostly on the lower extremities. The second primary melanomas developed in the same anatomic region from the first in 53.2% of our patients. The proportion of in situ to invasive melanomas was greater for the second melanomas compared with the first melanomas. Regarding invasive melanomas, the mean thickness of the first melanomas was 1.31 mm compared with 0.66 mm for the second ones. Dividing patients into two groups, of more and less than 50, it is highlighted that in older patients synchronous lesions appear more frequently (36.4% vs. 8.0%); the median time interval between sequential melanomas is longer (84 vs. 63.7 months); and the ratio between the primary and secondary melanoma mean thickness is lower (1.21 : 1.08 vs. 1.43 : 0.63 mm). CONCLUSIONS: The study confirms that second primary melanoma is usually thinner than the first lesion, and it is more common in the same region of the body as the initial melanoma. The highest risk for a second melanoma is during the first 5 years, but a much longer time interval of 28 years is possible. Continued medical follow-up with complete skin examinations seems prudent, but it is very important to promote self-skin evaluation in patients to detect not only metastases but also subsequent primary melanomas in their earliest phases. 相似文献
3.
4.
The impact of the Safe Kids/Healthy Neighborhoods Injury Prevention Program in Harlem, 1988 through 1991. 总被引:19,自引:6,他引:13 下载免费PDF全文
L L Davidson M S Durkin L Kuhn P O'Connor B Barlow M C Heagarty 《American journal of public health》1994,84(4):580-586
OBJECTIVES. This study evaluated the effectiveness of a community coalition to prevent severe injuries to children in Central Harlem, New York, NY. It was hypothesized that injury incidence rates would decline during the intervention (1989 through 1991) relative to preintervention years (1983 through 1988); that the decline would be greatest for the targeted age group (5 through 16 years) and targeted injury causes (traffic accidents, assaults, firearms, outdoor falls); and that the decline would occur in the intervention community rather than a control community. METHODS. Surveillance of injuries that result in hospitalization and/or death among children in the two communities has been under way since 1983. Data from this surveillance were used to test whether the incidence of severe injury declined during the intervention; other temporal variations were controlled by Poisson regression. RESULTS. The incidence of injury among school-aged children in central Harlem declined during the intervention. The decline was specific to the targeted age group and targeted causes. A nonspecific decline also occurred in the control community. CONCLUSIONS. The declining incidence rate in Central Harlem is consistent with a favorable program effect, but additional investigation of possible secular trend or spillover effects is needed. 相似文献
5.
6.
A Barlow 《Radiologic technology》1992,63(5):324-329
The use of radiolabeled antibodies may play a major role in future treatment of cancer patients, affecting procedural operations throughout both radiology and radiation therapy departments. Because of the number of different radioisotopes that may be used, education of medical personnel will be of critical importance. Adaptation of current radiology procedures may enhance this therapeutic modality. 相似文献
7.
8.
Effects of chain-length and unsaturation on affinity and selectivity at muscarinic receptors. 总被引:1,自引:1,他引:0 下载免费PDF全文
R. B. Barlow D. W. Holdup G. Harris M. A. Veale A. Williams 《British journal of pharmacology》1990,99(3):622-626
1. Lengthening the chain in diphenylacetylcholine decreases affinity for muscarinic cholinoceptors in guinea-pig ileum. Diphenylacetoxypropyldimethylamine and its quaternary trimethylammonium salt are roughly equiactive: the dimethylamine and the piperidine have some selectivity for ileum compared with atria, but are not as active nor as selective as 4-diphenylacetoxy-N-methylpiperidine (4-DAMP) methobromide (MeBr). With the weaker diphenylacetoxybutyl compounds the base is more active than the quaternary salt. 2. The diphenylacetoxybutyl-, cis-butenyl and trans-butenyl compounds have similar affinities. The quaternary salts are less active than the tertiary bases, but they are less selective than the butynyl analogues studied in earlier work. 3. 1,1-Diphenyl-1-hydroxy-2,4-hexadiynyl dimethylamine and its trimethylammonium salt are inactive in concentrations below 100 microM, as are the (+)-camphor-sulphonyl ester of 4-hydroxy-N-methyl piperidine and its methiodide. The (+/-)-phenylcyclopentylacetyl ester of 4-hydroxy-N-methylpiperidine methobromide is more active than its cyclohexyl analogue and than 4-DAMP MeBr but it is less selective than 4-DAMP MeBr. 4. The high selectivity of p-fluoro-hexahydrosila-diphenidol is confirmed but this compound has relatively low affinity (for ileum log K = 7.8). 5. The results indicate steric constraints to binding at muscarinic receptors which could be used to check molecular modelling of the receptor based on its known amino acid sequence. The group binding the charged nitrogen is probably at the mouth of a cavity which can accommodate two large rings (as in 4-DAMP MeBr) but with a depth less than about 7 A so that the rod-like hexadiynes cannot fit.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
9.
The syndrome of primary mitral leaflet billow, with or without prolapse, is associated with myxomatous degeneration of the mitral valve apparatus, mainly the posterior leaflet, and the syndrome may be familial. It manifests clinically with an isolated nonejection systolic click (billow), a murmur of mitral regurgitation that is usually late systolic (prolapse), or a combination of murmur and click. Echocardiography identifies and assesses the extent of the billowing of mitral leaflet bodies but there are no specific echocardiographic criteria that can differentiate normal from pathological billowing. Similarly, a prolapsed leaflet is not detected echocardiographically when there is localized and mild failure of leaflet edge apposition but a more severely prolapsed, or flail, leaflet can be demonstrated and confirmed by that technique. Symptoms of the syndrome include anxiety, chest pain and palpitations. The resting electrocardiogram may show ST segment and T wave abnormalities. The majority of patients have a benign course and require reassurance only. Complications include systemic emboli, infective endocarditis, progression to severe mitral regurgitation, arrhythmias and, rarely, sudden death. Patients with prolapse of a leaflet edge are more likely to develop complications than those with only billowing of the leaflet bodies. Surgery, preferably valvuloplasty, is required for severe regurgitation and may also be indicated for potentially lethal tachyarrhythmias unresponsive to medical therapy. Mitral leaflet billow and prolapse may be secondary to, or associated with, many conditions. The prognosis is then principally that of the underlying disease of which ischemic heart disease and hypertrophic cardiomyopathy are the most important. 相似文献
10.
S A Boyd A K Fung W R Baker R A Mantei Y L Armiger H H Stein J Cohen D A Egan J L Barlow V Klinghofer 《Journal of medicinal chemistry》1992,35(10):1735-1746
We describe the development of a series of soluble, potent, and bioavailable nonpeptide renin inhibitors. These inhibitors derived from a series of novel nonpeptide renin inhibitors which were recently identified in our laboratories, by alteration of the nature of the C-terminus (P2') of the molecules. Introduction of basic substituents into modified hydroxyethylene dipeptide isosteres gave inhibitors with improved solubility as well as improved potency against human plasma renin. In addition, these modifications produced inhibitors which displayed markedly improved intraduodenal bioavailability in both the ferret and cynomolgus monkey. We also present data which demonstrate excellent efficacy in the monkey for A-74273 (65), with an intraduodenal bioavailability of 16 +/- 4% in the monkey, compared to 1.7 +/- 0.5% for the dipeptide renin inhibitor enalkiren (A-64662, 75). A-74273 is an example of a nonpeptide inhibitor which possesses a good balance of the desirable properties of potency, solubility, and lipophilicity and which is well absorbed into the intestine. 相似文献