全文获取类型
收费全文 | 2401篇 |
免费 | 247篇 |
国内免费 | 13篇 |
专业分类
耳鼻咽喉 | 30篇 |
儿科学 | 52篇 |
妇产科学 | 37篇 |
基础医学 | 301篇 |
口腔科学 | 46篇 |
临床医学 | 323篇 |
内科学 | 525篇 |
皮肤病学 | 25篇 |
神经病学 | 125篇 |
特种医学 | 85篇 |
外科学 | 284篇 |
综合类 | 44篇 |
预防医学 | 243篇 |
眼科学 | 63篇 |
药学 | 190篇 |
中国医学 | 7篇 |
肿瘤学 | 281篇 |
出版年
2023年 | 21篇 |
2022年 | 38篇 |
2021年 | 75篇 |
2020年 | 40篇 |
2019年 | 54篇 |
2018年 | 89篇 |
2017年 | 53篇 |
2016年 | 48篇 |
2015年 | 72篇 |
2014年 | 91篇 |
2013年 | 114篇 |
2012年 | 160篇 |
2011年 | 159篇 |
2010年 | 99篇 |
2009年 | 98篇 |
2008年 | 139篇 |
2007年 | 149篇 |
2006年 | 115篇 |
2005年 | 118篇 |
2004年 | 139篇 |
2003年 | 131篇 |
2002年 | 103篇 |
2001年 | 58篇 |
2000年 | 67篇 |
1999年 | 47篇 |
1998年 | 22篇 |
1997年 | 19篇 |
1996年 | 12篇 |
1995年 | 15篇 |
1994年 | 10篇 |
1993年 | 18篇 |
1992年 | 35篇 |
1991年 | 34篇 |
1990年 | 22篇 |
1989年 | 29篇 |
1988年 | 17篇 |
1987年 | 23篇 |
1986年 | 17篇 |
1985年 | 8篇 |
1984年 | 13篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1981年 | 10篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 13篇 |
1976年 | 7篇 |
1972年 | 5篇 |
1971年 | 6篇 |
1970年 | 5篇 |
排序方式: 共有2661条查询结果,搜索用时 15 毫秒
11.
Solid-phase enzyme-linked immunosorbent assay for hepatitis E virus IgG and IgM antibodies utilizing recombinant antigens and synthetic peptides. 总被引:17,自引:0,他引:17
G J Dawson K H Chau C M Cabal P O Yarbough G R Reyes I K Mushahwar 《Journal of virological methods》1992,38(1):175-186
Four recombinant antigens representing two distinct antigenic domains from two different strains of hepatitis E virus (HEV), were used individually to develop four ELISAs designed to detect antibodies to HEV. Both IgG and IgM class antibodies to HEV were detected in 7 of 8 pedigreed serum/plasma from known outbreaks of HEV in Mexico, Burma, Somalia and Pakistan. In addition, specific HEV-antibodies were detected in cynomolgus macaques following inoculation with various HEV strains. Anti-HEV was also detected in 8 of 386 (2.1%) randomly selected American blood donors. Supplemental tests utilizing both synthetic peptides and specific blocking assays provided additional serologic data confirming the presence of anti-HEV. Similar prevalence studies on a limited number of available sera from other geographical regions (Alaska, Japan, Germany, New Zealand, Thailand and Mexico) confirmed the presence of anti-HEV in at least 1.1 to 7.6% of the specimens. 相似文献
12.
Quality of Life Research - To summarize the current evidence regarding the effectiveness of intradialytic exercise (IDE) on the health-related quality of life (HRQOL) of patients undergoing... 相似文献
13.
ObjectivesNon-traditional materials are used for mask construction to address personal protective equipment shortages during the coronavirus disease 2019 (COVID-19) pandemic. Reusable masks made from surgical sterilization wrap represent such an innovative approach with social media frequently referring to them as “N95 alternatives.” This material was tested for particle filtration efficiency and breathability to clarify what role they might have in infection prevention and control.MethodsA heavyweight, double layer sterilization wrap was tested when new and after 2, 4, 6, and 10 autoclave sterilizing cycles and compared with an approved N95 respirator and a surgical mask via testing procedures using a sodium chloride aerosol for N95 efficiency testing similar to 42 CFR 84.181. Pressure testing to indicate breathability was also conducted.ResultsThe particle filtration efficiency for the sterilization wrap ranged between 58% to 66%, with similar performance when new and after sterilizing cycles. The N95 respirator and surgical mask performed at 95% and 68% respectively. Pressure drops for the sterilization wrap, N95 and surgical mask were 10.4 mmH2O, 5.9 mmH2O, and 5.1 mmH2O, respectively, well below the National Institute for Occupational Safety and Health limits of 35 mmH2O during initial inhalation and 25 mmH2O during initial exhalation.ConclusionsThe sterilization wrap’s particle filtration efficiency is much lower than a N95 respirator, but falls within the range of a surgical mask, with acceptable breathability. Performance testing of non-traditional mask materials is crucial to determine potential protection efficacy and for correcting misinterpretation propagated through popular media. 相似文献
14.
Kenneth Siu-Sing Leung Timothy Ting-Leung Ng Alan Ka-Lun Wu Miranda Chong-Yee Yau Hiu-Yin Lao Ming-Pan Choi Kingsley King-Gee Tam Lam-Kwong Lee Barry Kin-Chung Wong Alex Yat Man Ho Kam-Tong Yip Kwok-Cheung Lung Raymond Wai-To Liu Eugene Yuk-Keung Tso Wai-Shing Leung Man-Chun Chan Yuk-Yung Ng Kit-Man Sin Kitty Sau-Chun Fung Sandy Ka-Yee Chau Wing-Kin To Tak-Lun Que David Ho-Keung Shum Shea Ping Yip Wing Cheong Yam Gilman Kit-Hang Siu 《Emerging infectious diseases》2021,27(1):196
Initial cases of coronavirus disease in Hong Kong were imported from mainland China. A dramatic increase in case numbers was seen in February 2020. Most case-patients had no recent travel history, suggesting the presence of transmission chains in the local community. We collected demographic, clinical, and epidemiologic data from 50 patients, who accounted for 53.8% of total reported case-patients as of February 28, 2020. We performed whole-genome sequencing to determine phylogenetic relationship and transmission dynamics of severe acute respiratory syndrome coronavirus 2 infections. By using phylogenetic analysis, we attributed the community outbreak to 2 lineages; 1 harbored a common mutation, Orf3a-G251V, and accounted for 88.0% of the cases in our study. The estimated time to the most recent common ancestor of local coronavirus disease outbreak was December 24, 2019, with an evolutionary rate of 3.04 × 10−3 substitutions/site/year. The reproduction number was 1.84, indicating ongoing community spread. 相似文献
15.
Wing-Hoi Cheung Vivian Wing-Yin Hung Ka-Yee Cheuk Wai-Wang Chau Kelvin Kam-Fai Tsoi Ronald Man-Yeung Wong Simon Kwoon-Ho Chow Tsz-Ping Lam Patrick Shu-Hang Yung Sheung-Wai Law Ling Qin 《Journal of bone and mineral research》2021,36(12):2381-2398
Osteoporosis is a systemic skeletal disease characterized by low bone mass and bone structural deterioration that may result in fragility fractures. Use of bone imaging modalities to accurately predict fragility fractures is always an important issue, yet the current gold standard of dual-energy X-ray absorptiometry (DXA) for diagnosis of osteoporosis cannot fully satisfy this purpose. The latest high-resolution peripheral quantitative computed tomography (HR-pQCT) is a three-dimensional (3D) imaging device to measure not only volumetric bone density, but also the bone microarchitecture in a noninvasive manner that may provide a better fracture prediction power. This systematic review and meta-analysis was designed to investigate which HR-pQCT parameters at the distal radius and/or distal tibia could best predict fragility fractures. A systematic literature search was conducted in Embase, PubMed, and Web of Science with relevant keywords by two independent reviewers. Original clinical studies using HR-pQCT to predict fragility fractures with available full text in English were included. Information was extracted from the included studies for further review. In total, 25 articles were included for the systematic review, and 16 articles for meta-analysis. HR-pQCT was shown to significantly predict incident fractures and/or major osteoporotic fractures (MOFs). Of all the HR-pQCT parameters, our meta-analysis revealed that cortical volumetric bone mineral density (Ct.vBMD), trabecular thickness (Tb.Th), and stiffness were better predictors. Meanwhile, HR-pQCT parameters indicated better performance in predicting MOFs than incident fractures. Between the two standard measurement sites of HR-pQCT, the non-weight-bearing distal radius was a more preferable site than distal tibia for fracture prediction. Furthermore, most of the included studies were white-based, whereas very few studies were from Asia or South America. These regions should build up their densitometric databases and conduct related prediction studies. It is expected that HR-pQCT can be used widely for the diagnosis of osteoporosis and prediction of future fragility fractures. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR). 相似文献
16.
Ronald C. Johnson PhD Craig T. Nagoshi PhD† George P. Danko MA Kelly Ann M. Honbo MA Lai Ling Chau BA 《Alcoholism, clinical and experimental research》1990,14(2):216-220
Members of 183 families (biological parents and one adult offspring) completed questionnaires on their quantity and frequency of alcohol use, what they would consider a "normal" quantity-frequency of alcohol use, "problem" quantity-frequency of use, flushing after alcohol use, and other expected physiological and subjective responses to alcohol. Within individuals, own quantity-frequency of alcohol use was moderately negatively correlated with flushing after one drink or less ("fast flushing"), but more highly positively correlated with judged normal alcohol use and with expected subjective effects. Spouse resemblances were low for quantity-frequency of alcohol use and flushing, but high for alcohol use norms and expected physiological and subjective responses. Parent-offspring resemblances were low to moderate for own alcohol use and flushing, but moderate to high for expected physiological and subjective effects. These results were discussed in terms of the effects of genetically transmitted flushing after alcohol use and culturally transmitted alcohol norms and expectations on alcohol use. 相似文献
17.
GABA(A) receptors mediate inhibition of T cell responses 总被引:4,自引:0,他引:4
We describe the presence of functional GABA(A) receptors on T cells. GABA inhibited anti-CD3 and antigen-specific T cell proliferation in vitro in a dose-dependent manner that was 1) mimicked by the GABA(A) receptor agonist muscimol (but not the GABA(B) receptor agonist baclofen), 2) blocked by GABA(A) receptor antagonists and a GABA(A) receptor Cl- channel blocker (picrotoxin) and 3) enhanced by pentobarbital. These data suggest that GABA(A) receptors mediate this immune inhibition and that these receptors can be modulated in a similar fashion to their neuronal counterparts. Finally, GABA inhibited DTH responses in vivo. Thus, pharmacological modulation of GABA(A) receptors may provide new approaches to modulate T cell responses in inflammation and autoimmune disease. 相似文献
18.
Experts from the Food and Drug Administration (FDA) of the USA have assumed that hypertensive patients are likely to achieve greatest benefit from therapy in which the antihypertensive effects do not vary excessively during the course of the day. They suggested that the ratio of the minimal (trough) effect to the maximal (peak) effect of the drug should be no lower than 0.5. The concept of the trough: peak ratio (TPR) raises many practical problems. Using actual data, the effect of a drug often shows erratic fluctuations with several local minima and maxima. Mean blood pressure levels for several hours have been used to estimate the trough and peak effects. Blood pressure averages over 4 h may e a good choice, because blood pressures measured 4 h apart are not correlated. The statistical distribution of the TPR is not Gaussian. Negative and very low or positive and very high individual ratios are frequently observed. Therefore, the individual TPR is of questionable clinical value, except when the ratio is applied for responders only. The TPR can be calculated for a sample. In that case, the bootstrap method can be used to estimate the error of the TPR. Most important is the question of why the TPR should be higher than 0.5. We introduced the concept of 'normalization of the blood pressure profile', namely 'reducing the blood pressure profiles in hypertensives to match those profiles in normotensives'. This concept leads very naturally to the TPR and justifies the lower limit of 0.5 for the TPR. 相似文献
19.
In 1989, the French PCV-METRA Group (PCV-METRA = Prévention Cardio-Vasculaire en Médecine du Travail) started a large prospective survey of cardiovascular (CDV) morbidity and mortality and of CVD risk factors, especially cholesterol, in a working population in Ile-de-France, a region including Paris. This report presents the first results of this study, based on a sample of 5758 men and 2603 women, aged 18–65 years. The variables examined included the levels of total cholesterol (TC), High-density-lipooprotein cholesterol (HDL-C), low-density-lipoprotein cholesterol (LDL-C), and the other major CVD risk factors (smoking, sedentary way of life, hypertension, hypercholesterolemia, use of oral contraceptives and familial history of CVD risks). TC and LDL-C significantly increased with age. The changes with age were significantly different in men and women. The levels were similar in both sexes at less than 30 yrs, increased sharply for men after age 30 and were significantly higher in men than in women from 30 to 55 yrs. Beyond 55 yrs, no difference was obserbed between the two sexes. In contrast, HDL-C was higher in women at all age ranges. In the total sample, 35% of men and 21% of women were hypercholesterolemic (TC 2.4 g/ L). Our observations fully confirm and refine previous findings in the US and in other European countries. In addition, a substantial set of data on CVD risk factors for the working population in France, especially for female subjects for whom data are scanty, is now available.Corresponding author. 相似文献
20.
Two lines of rats, least affected (LA) and most affected (MA), had been selectively bred for their differential sensitivity to ethanol. Both males and females of the LA strain were observed to be less sensitive than their MA counterparts to the acute hypnotic and motor-impairing effects of ethanol. However, a lower ethanol metabolic rate of the MA males suggests that both CNS and metabolic factors contribute to their enhanced sensitivity to ethanol. By contrast, no differences were observed between the LA and MA males with respect to the hypnotic and subhypnotic effects of pentobarbital or to the clearance of this drug. MA females were more sensitive only to the hypnotic effects of pentobarbital, probably because of a smaller apparent volume of distribution. No strain difference was observed in the hypnotic effect or clearance of barbital. These observations suggest that, in spite of a differential sensitivity to ethanol, the LA and MA lines do not differ in their response to the barbiturates tested. 相似文献