全文获取类型
收费全文 | 17445篇 |
免费 | 1407篇 |
国内免费 | 19篇 |
专业分类
耳鼻咽喉 | 421篇 |
儿科学 | 610篇 |
妇产科学 | 544篇 |
基础医学 | 1931篇 |
口腔科学 | 241篇 |
临床医学 | 1590篇 |
内科学 | 3236篇 |
皮肤病学 | 419篇 |
神经病学 | 1388篇 |
特种医学 | 847篇 |
外科学 | 3451篇 |
综合类 | 467篇 |
一般理论 | 9篇 |
预防医学 | 1390篇 |
眼科学 | 405篇 |
药学 | 790篇 |
中国医学 | 5篇 |
肿瘤学 | 1127篇 |
出版年
2021年 | 123篇 |
2020年 | 111篇 |
2019年 | 152篇 |
2018年 | 208篇 |
2017年 | 144篇 |
2016年 | 161篇 |
2015年 | 664篇 |
2014年 | 797篇 |
2013年 | 910篇 |
2012年 | 1070篇 |
2011年 | 1002篇 |
2010年 | 843篇 |
2009年 | 848篇 |
2008年 | 1041篇 |
2007年 | 1082篇 |
2006年 | 982篇 |
2005年 | 885篇 |
2004年 | 704篇 |
2003年 | 472篇 |
2002年 | 450篇 |
2001年 | 412篇 |
2000年 | 394篇 |
1999年 | 380篇 |
1998年 | 189篇 |
1997年 | 180篇 |
1996年 | 147篇 |
1995年 | 127篇 |
1994年 | 141篇 |
1993年 | 154篇 |
1992年 | 299篇 |
1991年 | 256篇 |
1990年 | 251篇 |
1989年 | 265篇 |
1988年 | 213篇 |
1987年 | 212篇 |
1986年 | 184篇 |
1985年 | 192篇 |
1984年 | 151篇 |
1983年 | 163篇 |
1982年 | 117篇 |
1981年 | 90篇 |
1980年 | 89篇 |
1979年 | 136篇 |
1978年 | 100篇 |
1977年 | 99篇 |
1976年 | 104篇 |
1974年 | 105篇 |
1973年 | 98篇 |
1972年 | 93篇 |
1971年 | 88篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
According to the guidelines, ultrasonography (US) is now established as the cross-sectional imaging technique of choice in postoperative care of colorectal carcinoma. Although conventional percutaneous US is inferior to computed tomography (CT) and magnetic resonance imaging (MRI) for detecting hepatic metastases, the application of specific contrast media has significantly increased sensitivity and specificity to 87% and 88%, respectively. The combination of US and CT/MRI achieves the highest detection rates. During follow-up of rectal carcinoma, in up to 20% of locoregional recurrences are diagnosed solely by endorectal sonography and result in repeat resection with curative intention. In noncolorectal carcinoma, US is recommended in the guidelines for following up hepatocellular carcinoma and malignant thyroid disease, but the available data are insufficient to support those recommendations. 相似文献
32.
33.
34.
A rapid, inexpensive beryllium acute toxicity assay using human erythrocyte ATP levels has been developed. The assay uses a photometric measurement of the luciferin-luciferase reaction in erythrocytes incubated in HEPES buffer with the tested toxicant. Incubation in HEPES significantly increases the sensitivity of erythrocytes to beryllium when compared to incubation in either plasma or physiological saline. After a one-hour incubation period in HEPES buffer and beryllium there is a loss of 50% of the erythrocyte ATP at 3 micrograms/ml of beryllium, and an 80% loss of ATP at 5 micrograms/ml of beryllium. The source of human erythrocytes does not appear to influence the test. Erythrocytes from 10 individuals, one with chronic beryllium disease and another with an acute sensitivity to beryllium, all gave similar biphasic dose-response curves to beryllium. 相似文献
35.
PD Dr. T. F. Schwarz M. D. Prof. H. Nsanze M. D. Prof. A. M. Ameen M. D. 《Infection》1997,25(6):364-367
Summary Crimean-Congo haemorrhagic fever (C-CHF) re-emerged recently in the United Arab Emirates. The clinical outcome of 11 cases of viral haemorrhagic fever patients admitted to hospital between June 1994 and January 1995 is described. Four cases were laboratory confirmed retrospectively as C-CHF, the other patients were diagnosed likely to have the same disease on epidemiological and clinical grounds. In 72.7% of the patients, infection was fatal. Symptoms started 3.5 days before hospitalization. On admission, 81.8% of patients had high fever, 45.5% were vomiting, 63.6% had diarrhoea, 45.5% had haemorrhagic signs, and 18.2% had throat pain. Fatalities occurred 6.8 days after admission. Survivors were hospitalized for 9.3 days. Nosocomial transmission was not observed. 相似文献
36.
S P Newman G Woodman F Morén S W Clarke 《British journal of diseases of the chest》1988,82(3):262-267
Metered dose inhalers are sometimes used in conjunction with NebuhalerR, a 750 ml holding chamber, but the permissible delay time between actuating the aerosol into Nebuhaler and commencing inhalation is unknown. We have compared in 10 asthmatic patients the bronchodilator responses following inhalations of terbutaline sulphate from Nebuhaler after delays of 1, 5 and 30 seconds and following placebo inhalation. Terbutaline sulphate was administered as 2 puffs, each of 250 micrograms, separated by approximately 15 minutes. After each delay time, terbutaline produced increases in forced expiratory volume in one second (FEV1), peak expiratory flow rate (PEFR) and maximum expiratory flow following exhalation of 75% of the forced vital capacity (V max25) significantly greater than those after placebo (P less than 0.01). Changes in PEFR did not vary significantly among the three delay times, but the increases in FEV1 and in V max25 were significantly reduced with 30 seconds' delay. It is concluded that the delay between actuation into Nebuhaler and commencing inhalation can be extended from 1 second to 5 seconds without significant loss of drug efficacy, and that further extension to 30 seconds causes only a small loss of bronchodilatation: hence the delay time is unlikely to be of major importance in clinical practice. 相似文献
37.
Seating arrangements for cerebral palsy children with total body involvement are often unsatisfactory and can pose considerable problems for the multi-disciplinary team. Hip joints at risk of dislocation must be kept in an abducted position in order to minimize pain. A new wheelchair with a barrel-shaped cylindrical seat has been developed which improves the femoral head location and alleviates pain. 相似文献
38.
F Leonessa V Boulay A Wright E W Thompson N Brünner R Clarke 《Acta oncologica (Stockholm, Sweden)》1992,31(2):115-123
Many breast tumors appear to follow a predictable clinical pattern, being initially responsive to endocrine therapy and to cytotoxic chemotherapy but ultimately exhibiting a phenotype resistant to both modalities. Using the MCF-7 human breast cancer cell line as an example of an 'early' phenotype (estrogen and progesterone receptor positive, steroid responsive, low metastatic potential), we have isolated and characterized a series of hormone-independent but hormone-responsive variants (MIII and MCF7/LCC1). However, these variants remain responsive to both antiestrogens and cytotoxic drugs (methotrexate and colchicine). MIII and MCF7/LCC1 cells appear to mimic some of the critical aspects of the early progression to a more aggressive phenotype. An examination of the phenotype of these cells suggests that some hormone-independent breast cancer cells are derived from hormone-dependent parental cells. The development of a hormone-independent phenotype can arise independently of acquisition of a cytotoxic drug resistant phenotype. 相似文献
39.
Changes in regional ventilation and perfusion of the lung after endoscopic laser treatment. 总被引:4,自引:2,他引:2 下载免费PDF全文
To determine whether endoscopic laser treatment improves both ventilation and perfusion in patients with advanced lung cancer, krypton-81m ventilation and technetium-99m labelled macro-aggregate perfusion scanning was performed immediately before and two or four days after treatment in a consecutive series of 28 patients. Twelve patients had not received any other treatment before laser therapy and 16 had undergone previous treatments that included radiotherapy. Ventilation and perfusion were quantified by expressing the number of counts in the affected lung as a percentage of the total counts. Ventilation and perfusion improved after laser treatment in 23 patients (82%). The mean ventilation score in the affected lung rose by 50% (p less than 0.001) and the mean perfusion score rose by 24% (p less than 0.001). Incremental changes in ventilation and perfusion scores were positively correlated (r = 0.80). Mean spirometric values, six minute walking distance, the Karnofsky performance index, and breathlessness and wellbeing scores also improved significantly. Patients with main bronchial obstruction who had had no radiotherapy showed the most striking improvements. It is concluded that the removal of intraluminal tumour from the bronchial tree leads to matched improvements in ventilation and perfusion in most patients and that this is associated with valuable improvement in symptoms. 相似文献
40.