全文获取类型
收费全文 | 19365篇 |
免费 | 1422篇 |
国内免费 | 116篇 |
专业分类
耳鼻咽喉 | 150篇 |
儿科学 | 620篇 |
妇产科学 | 470篇 |
基础医学 | 2378篇 |
口腔科学 | 398篇 |
临床医学 | 1892篇 |
内科学 | 4126篇 |
皮肤病学 | 259篇 |
神经病学 | 1542篇 |
特种医学 | 557篇 |
外科学 | 2650篇 |
综合类 | 380篇 |
一般理论 | 13篇 |
预防医学 | 1614篇 |
眼科学 | 1129篇 |
药学 | 1310篇 |
2篇 | |
中国医学 | 107篇 |
肿瘤学 | 1306篇 |
出版年
2023年 | 209篇 |
2022年 | 302篇 |
2021年 | 633篇 |
2020年 | 395篇 |
2019年 | 523篇 |
2018年 | 586篇 |
2017年 | 423篇 |
2016年 | 379篇 |
2015年 | 455篇 |
2014年 | 605篇 |
2013年 | 815篇 |
2012年 | 1201篇 |
2011年 | 1230篇 |
2010年 | 717篇 |
2009年 | 644篇 |
2008年 | 1042篇 |
2007年 | 1176篇 |
2006年 | 1051篇 |
2005年 | 1016篇 |
2004年 | 960篇 |
2003年 | 880篇 |
2002年 | 790篇 |
2001年 | 538篇 |
2000年 | 475篇 |
1999年 | 408篇 |
1998年 | 169篇 |
1997年 | 146篇 |
1996年 | 129篇 |
1995年 | 97篇 |
1994年 | 107篇 |
1993年 | 102篇 |
1992年 | 244篇 |
1991年 | 241篇 |
1990年 | 211篇 |
1989年 | 171篇 |
1988年 | 181篇 |
1987年 | 204篇 |
1986年 | 147篇 |
1985年 | 140篇 |
1984年 | 96篇 |
1983年 | 124篇 |
1982年 | 74篇 |
1981年 | 63篇 |
1980年 | 67篇 |
1979年 | 94篇 |
1978年 | 71篇 |
1977年 | 38篇 |
1976年 | 38篇 |
1974年 | 37篇 |
1973年 | 38篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
alpha-1 antitrypsin phenotypes by isoelectric focusing in a metropolitan southern Chinese population 下载免费PDF全文
AIMS/BACKGROUND: alpha-1 antitrypsin (alpha1AT) is an abundant protease inhibitor in human plasma. Its phenotypic variability has been reported to be associated with pulmonary emphysema and chronic liver diseases. However, alpha1AT deficiency is an uncommon condition in the Chinese population. The aim of this study was to describe the phenotypic distribution of alpha1AT in a southern Chinese population. METHODS: A total of 1085 healthy blood donors underwent alpha1AT phenotyping by isoelectric focusing. RESULTS: Two thirds (66.1%) were homozygous for either M1 or M2, whereas 32.6% were heterozygous for two different M phenotypes. The frequency of allelic variants was only 0.007, and deficiency variants were absent. Compared with earlier studies on southern Chinese populations, this study found a lower frequency of M2, and a higher number of allelic variants, including E, L, N, P, and S. This phenomenon can be attributed to population migration and mixing. CONCLUSIONS: An understanding of the alpha1AT pattern is important for evaluating the predisposition of the population to selected clinical diseases. 相似文献
93.
94.
95.
Twenty cases of non-Hodgkin's malignant lymphoma were examined using both flow cytometry (FCM) and static cytometry (SCM) DNA analysis to detect aneuploidic cell populations. FCM was performed on fresh cell suspensions whilst SCM was performed retrospectively on formalin-fixed, paraffin-embedded samples of the same tissue. A total of 34 aneuploidic cell lines were detected by FCM compared to a total of 41 detected by SCM. Of the 20 cases 14 showed DNA indexes within 10% of each other for each method, indicating a reasonable degree of comparability between the two methods. Of the 6 cases which did not show comparable DNA indexes, 2 displayed similar cell lines for both methods, but the major abnormal cell populations were of different ploidy by SCM as compared to FCM. A qualitative comparison is thus possible between these two cases. The results suggest that retrospectively applied SCM ploidy analysis of lymphoid tissue is comparable to FCM on fresh tissue samples and can thus be used in retrospective studies of both prognostic and diagnostic significance. 相似文献
96.
97.
Ramaseshan R Kohli KS Zhang TJ Lam T Norlinger B Hallil A Islam M 《Physics in medicine and biology》2004,49(17):4031-4048
The commercially available microMOSFET dosimeter was characterized for its dosimetric properties in radiotherapy treatments. The MOSFET exhibited excellent correlation with the dose and was linear in the range of 5-500 cGy. No measurable effect in response was observed in the temperature range of 20-40 degrees C. No significant change in response was observed by changing the dose rate between 100 and 600 monitor units (MU) min(-1) or change in the dose per pulse. A 3% post-irradiation fading was observed within the first 5 h of exposure and thereafter it remained stable up to 60 h. A uniform energy response was observed in the therapy range between 4 MV and 18 MV. However, below 0.6 MeV (Cs-132), the MOSFET response increased with the decrease in energy. The MOSFET also had a uniform dose response in 6-20 MeV electron beams. The directional dependence of MOSFET was within +/-2% for all the energies studied. The inherent build-up of the MOSFET was evaluated dosimetrically and found to have varying water equivalent thickness, depending on the energy and the side of the beam entry. At depth, a single calibration factor obtained by averaging the MOSFET response over different field sizes, energies, orientation and depths reproduced the ion chamber measured dose to within 5%. The stereotactic and the penumbral measurements demonstrated that the MOSFET could be used in a high gradient field such as IMRT. The study showed that the microMOSFET dosimeter could be used as an in vivo dosimeter to verify the dose delivery to the patient to within +/-5%. 相似文献
98.
Oral acyclovir and herpes labialis: a randomized, double-blind, placebo-controlled study 总被引:2,自引:0,他引:2
G W Raborn W T McGaw M Grace L D Tyrrell S M Samuels 《Journal of the American Dental Association (1939)》1987,115(1):38-42
A study of the effects of oral acyclovir (200 mg), administered five times per day for 5 days in 210 patients who cultured positive for herpes labialis, is made. A total of 149 patients were followed through three episodes each of herpes labialis while taking a placebo or acyclovir. Patients were evaluated for several clinical parameters, including the loss of lesion crust and reduction of the size of the area of the lesion between day 1 and day 5. Acyclovir showed a significant antiviral effect. Results show that oral acyclovir can favorably affect some parameters, but that higher doses or a "loading dose" could improve its efficacy. 相似文献
99.
Priyanka Sharma Guojun Wu Deeptha Kumaraswamy Natalie Burchat Hong Ye Yongjia Gong Liping Zhao Yan Y. Lam Harini Sampath 《Nutrients》2021,13(2)
7,8-Dihydroxyflavone (DHF) is a naturally occurring flavonoid that has been reported to protect against a variety of pathologies. Chronic administration of DHF prevents high-fat diet (HFD)-induced obesity in female, but not male, mice. However, the mechanisms underlying this sexual dimorphism have not been elucidated. We have discovered that oral DHF supplementation significantly attenuates fat mass, hepatic lipid accumulation, and adipose tissue inflammation in female mice. In contrast, male mice were not protected from adiposity, and had a paradoxical worsening of hepatic lipid accumulation and adipose tissue inflammation upon DHF supplementation. Consistent with these sexually dimorphic effects on body weight and metabolic health, 7,8-DHF induced early and stable remodeling of the female intestinal microbiome. DHF supplementation significantly increased gut microbial diversity, and suppressed potentially detrimental bacteria, particularly Desulfovibrionaceae, which are pro-inflammatory and positively associated with obesity and inflammation. Changes in the female gut microbiome preceded alterations in body weights, and in silico analyses indicated that these early microbial changes were highly predictive of subsequent weight gain in female mice. While some alterations in the intestinal microbiome were also observed in male DHF-supplemented mice, these changes were distinct from those in females and, importantly, were not predictive of subsequent body weight changes in male animals. The temporality of microbial changes preceding alterations in body weight in female mice suggests a role for the gut microbiome in mediating the sexually dimorphic effects of DHF on body weight. Given the significant clinical interest in this flavonoid across a wide range of pathologies, further elucidation of these sexually dimorphic effects will aid the development of effective clinical therapies. 相似文献
100.
Functional dyspepsia (FD) is a common disorder of gut-brain interaction, characterised by upper gastrointestinal symptom profiles that differentiate FD from the irritable bowel syndrome (IBS), although the two conditions often co-exist. Despite food and eating being implicated in FD symptom induction, evidence-based guidance for dietetic management of FD is limited. The aim of this narrative review is to collate the possible mechanisms for eating-induced and food-related symptoms of FD for stratification of dietetic management. Specific carbohydrates, proteins and fats, or foods high in these macronutrients have all been reported as influencing FD symptom induction, with removal of ‘trigger’ foods or nutrients shown to alleviate symptoms. Food additives and natural food chemicals have also been implicated, but there is a lack of convincing evidence. Emerging evidence suggests the gastrointestinal microbiota is the primary interface between food and symptom induction in FD, and is therefore a research direction that warrants substantial attention. Objective markers of FD, along with more sensitive and specific dietary assessment tools will contribute to progressing towards evidence-based dietetic management of FD. 相似文献