全文获取类型
收费全文 | 1020篇 |
免费 | 90篇 |
专业分类
耳鼻咽喉 | 9篇 |
儿科学 | 34篇 |
妇产科学 | 33篇 |
基础医学 | 98篇 |
口腔科学 | 20篇 |
临床医学 | 217篇 |
内科学 | 219篇 |
皮肤病学 | 18篇 |
神经病学 | 46篇 |
特种医学 | 172篇 |
外科学 | 66篇 |
综合类 | 39篇 |
预防医学 | 58篇 |
眼科学 | 3篇 |
药学 | 42篇 |
肿瘤学 | 36篇 |
出版年
2022年 | 6篇 |
2021年 | 14篇 |
2019年 | 6篇 |
2018年 | 22篇 |
2017年 | 9篇 |
2016年 | 17篇 |
2015年 | 17篇 |
2014年 | 23篇 |
2013年 | 43篇 |
2012年 | 28篇 |
2011年 | 16篇 |
2010年 | 42篇 |
2009年 | 48篇 |
2008年 | 39篇 |
2007年 | 27篇 |
2006年 | 22篇 |
2005年 | 33篇 |
2004年 | 23篇 |
2003年 | 27篇 |
2002年 | 13篇 |
2001年 | 18篇 |
2000年 | 24篇 |
1999年 | 32篇 |
1998年 | 31篇 |
1997年 | 41篇 |
1996年 | 35篇 |
1995年 | 33篇 |
1994年 | 31篇 |
1993年 | 29篇 |
1992年 | 13篇 |
1991年 | 22篇 |
1990年 | 17篇 |
1989年 | 24篇 |
1988年 | 16篇 |
1987年 | 22篇 |
1986年 | 20篇 |
1985年 | 17篇 |
1984年 | 12篇 |
1983年 | 14篇 |
1982年 | 11篇 |
1981年 | 12篇 |
1979年 | 13篇 |
1978年 | 17篇 |
1977年 | 18篇 |
1976年 | 18篇 |
1975年 | 19篇 |
1974年 | 7篇 |
1973年 | 6篇 |
1972年 | 6篇 |
1924年 | 5篇 |
排序方式: 共有1110条查询结果,搜索用时 187 毫秒
21.
22.
23.
J.A. Stillman R.P. Morton K.D. Hay Z. Ahmad D. Goldsmith 《Clinical otolaryngology》2003,28(5):406-410
Electrogustometry is well established as a clinical tool for the estimation of taste detection thresholds. Nevertheless, the user is sometimes unaware of the impact of superficially minor procedural and psychophysical factors upon the reliability and comparability of threshold estimates. The inherent strengths and limitations of the procedure are outlined, and aspects of the control and specification of the stimulus that moderate threshold measures are discussed. In addition, threshold estimates from two individuals with severe unilateral taste loss are used to illustrate the level at which anodal dc current may elicit common, rather than taste, sensation. Where chorda tympani section is complete and historical (older than 7–14 days), very high stimulus levels, conservatively over 5 µA/mm2 (100 µA linear current with a 5‐mm diameter electrode), are required to activate trigeminal responses. 相似文献
24.
Black tea and mammary gland carcinogenesis by 7,12- dimethylbenz[a]anthracene in rats fed control or high fat diets 总被引:3,自引:1,他引:3
Epidemiological studies suggest that tea may reduce cancer risk, and in
laboratory rodents, chemopreventive effects of tea or purified extracts of
tea have been demonstrated in lung, gastrointestinal tract and skin. There
is some evidence of chemoprevention by tea in the mammary gland, but the
data are not conclusive. In order to evaluate more fully the possible
influence of black tea on 7,12-dimethylbenz[a]anthracene (DMBA)-induced
mammary gland tumors in the female S-D (Sprague-Dawley) rat, three large
studies were performed: experiment 1, tumorigenesis in rats fed AIN-76A
diet and given 25 mg/kg DMBA and 1.25 or 2.5% whole tea extract or water to
drink; experiment 2, tumorigenesis in rats given 15 mg/kg DMBA and the same
diet and fluids as in experiment 1; experiment 3, tumorigenesis in rats fed
control or HF (high fat, corn oil) diet and given 15 mg/kg DMBA and 2% tea
or water to drink. Tea was given throughout the experiment; DMBA was given
by gastric gavage at 8 weeks of age. There was no consistent effect of tea
on tumorigenesis in rats fed AIN-76A diet; there was, however, evidence in
experiment 3 of a reduction of tumorigenesis by tea in rats fed the HF
diet. In experiment 3, rats fed the HF diet and given water showed the
expected increase in tumor burden (number and weight) compared with rats
fed control diet. However, rats fed the HF diet and given 2% tea showed no
increase in tumor burden; their tumor burden was significantly lower than
in rats fed the HF diet and given water (P < 0.01) and was not different
from rats fed control diet and given water or tea. In addition, in
experiment 3, the number of malignant tumors per tumor- bearing rat was
increased by the HF diet in water-drinking rats (P < 0.01) but not in
tea-drinking rats. Therefore, it appears that tea partially blocked the
promotion of DMBA-induced mammary tumorigenesis by the HF diet.
相似文献
25.
Al-Bahry SN Al-Mashani BM Al-Ansari AS Elshafie AE Mahmoud IY 《Asian Pacific journal of tropical medicine》2013,6(9):718-722
ObjectiveTo screen for Escherichia coli (E. coli) resistant to tetracycline, followed by identification of tet efflux genes by polymerase chain reaction (PCR). In addition, detection of tetracycline residues in chicken livers and kidneys were conducted using high performance liquid chromatography-tandem quadrupole mass spectrometry (HPLC-MS-MS).MethodsStrains of E. coli were isolated from samples of chicken colon and screened for tetracycline resistance. Tetracycline genes conferring resistance (Tcr) were detected by polymerase chain reaction (PCR). Most of the isolates were resistant to tetracycline (97.9%).ResultsPCR analysis indicated that Tcr E. coli R-plasmids contained tet(A), tet(B) and a combination of both efflux genes. None of the isolates contained other efflux tet genes tet (C, D, E and Y). High performance liquid chromatography-tandem quadrupole mass spectrometry (HPLC-MS-MS), a sensitive technique, was used to detect residues of chlortetracycline (CTC), oxytetracycline (OTC), doxycycline (DC) in chicken livers and kidneys. The samples containing tetracycline residues were at 0.13-0.65 pg/μL levels.ConclusionsTetracycline and other antibiotics are commonly used in the poultry and meat production industry for prevention of microbial infections. Multiple antibiotic resistant bacteria in Oman have increased to alarming levels, threatening public health, domestic and may have adverse effect on environment. 相似文献
26.
27.
28.
29.
AF Jorm H Christensen AS Henderson PA Jacomb AE Korten A Mackinnon 《Age and ageing》1996,25(2):126-129
Formal assessment of cognitive decline with cognitive tests can be difficult, requiring either two measurement points or a comparison of 'hold' with 'don't hold' tests. Informant-based assessment provides an alternative approach because informants can adopt a longitudinal perspective and directly rate cognitive change. A study was carried out to assess the validity of informant ratings collected by means of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE). A community sample of 500 subjects aged 74 or over underwent four cognitive tests on two occasions 3½ years apart. On the second occasion, informants filled out the IQCODE. Subjects rated as having moderate or severe decline were found to have greater change on the cognitive tests. These findings support the validity of informant ratings of cognitive decline. 相似文献
30.
The effect of azathioprine on the kinetics of peripheral blood monocytes and peritoneal macrophages was studied in normal mice and in mice in which an inflammatory reaction was provoked. Two dosage levels were used: a high dose of 200mg/kg which is the maximum tolerated daily dose in mice, and low dose of 3 mg/kg which is about equivalent to a nontoxic, immunosuppressive, anti-inflammatory dose in man. The number of peripheral blood monocytes decreases gradually during azathioprine treatment of normal mice, the extent and duration being dependent on the dose and duration of administered over a period of 9 days gives an almost complete reduction, and a low dose (3 mg/kg) given for the same period results in a reduction of about 50%. This effect seems to be reversible, because when treatment is stopped the number of monocytes starts to increase 24-48 hr later. The number of peritoneal macrophages is only affected when a high dose (200 mg/kg) is given over a long period; a low dose has virtually no effect. In mice in which an inflammatory reaction was prevoked in the peritoneal cavity, the normally occurring increase in the numbers of both peripheral blood monocytes and peritoneal macrophages was suppressed, the extent being dependent on the dose of azathioprine administered. Labeling studies with 3H-thymidine indicated that the reduction of peripheral blood monocytes and peritoneal macrophages in the inflammatory exudate is due to a diminished monocyte production. 相似文献