全文获取类型
收费全文 | 11162篇 |
免费 | 668篇 |
国内免费 | 160篇 |
专业分类
耳鼻咽喉 | 186篇 |
儿科学 | 152篇 |
妇产科学 | 239篇 |
基础医学 | 1720篇 |
口腔科学 | 244篇 |
临床医学 | 909篇 |
内科学 | 1995篇 |
皮肤病学 | 572篇 |
神经病学 | 665篇 |
特种医学 | 721篇 |
外科学 | 1808篇 |
综合类 | 59篇 |
一般理论 | 1篇 |
预防医学 | 612篇 |
眼科学 | 197篇 |
药学 | 979篇 |
中国医学 | 157篇 |
肿瘤学 | 774篇 |
出版年
2023年 | 59篇 |
2022年 | 231篇 |
2021年 | 357篇 |
2020年 | 180篇 |
2019年 | 279篇 |
2018年 | 301篇 |
2017年 | 215篇 |
2016年 | 353篇 |
2015年 | 492篇 |
2014年 | 590篇 |
2013年 | 684篇 |
2012年 | 975篇 |
2011年 | 954篇 |
2010年 | 598篇 |
2009年 | 464篇 |
2008年 | 657篇 |
2007年 | 637篇 |
2006年 | 557篇 |
2005年 | 559篇 |
2004年 | 424篇 |
2003年 | 370篇 |
2002年 | 333篇 |
2001年 | 222篇 |
2000年 | 226篇 |
1999年 | 186篇 |
1998年 | 77篇 |
1997年 | 59篇 |
1996年 | 58篇 |
1995年 | 37篇 |
1994年 | 35篇 |
1993年 | 36篇 |
1992年 | 61篇 |
1991年 | 60篇 |
1990年 | 56篇 |
1989年 | 40篇 |
1988年 | 50篇 |
1987年 | 40篇 |
1986年 | 43篇 |
1985年 | 48篇 |
1984年 | 39篇 |
1983年 | 50篇 |
1982年 | 17篇 |
1981年 | 16篇 |
1980年 | 16篇 |
1979年 | 30篇 |
1978年 | 27篇 |
1977年 | 22篇 |
1976年 | 19篇 |
1974年 | 17篇 |
1973年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Jennifer C. Chen Katrina L. Schmid Brian Brown Marion H. Edwards Bibianna SY Yu John KF Lew 《Clinical & experimental optometry》2003,86(5):323-330
Purpose: Caucasian children with myopia have elevated response accommodative vergence to accommodation (AC/A) ratios. The purpose of this study was twofold: to determine if response AC/A ratios vary with refractive error and with myopic progression rate in Hong Kong Chinese children, and to determine the effect of beta‐adrenergic antagonism with topical timolol application on AC/A ratios. Methods: Thirty children aged eight to 12 years participated in the study. All refractive errors were corrected with spectacle lenses. Accommodative responses were measured using a Shin‐Nippon autorefractor and concurrent changes in vergence were assessed using a vertical prism and a Howell‐Dwyer card at three metres and 0.33 metre. Accommodative demand was altered using plus or minus two dioptre lenses and lens‐ and distance‐induced response AC/A ratios were calculated. Measurements were repeated 30 minutes after the instillation of topical timolol maleate (0.5 per cent). Results: AC/A ratios appeared higher in progressing myopic children but the difference was not statistically significant. Timolol application reduced accommodative convergence (AC) in the stable myopes (reduction = ‐3 ± 1.14A) but not in the emmetropes (0.69 ± 0.9P) or progressing myopes (0.16 ± 0.43A) and this difference between refractive groups was statistically s ignificant (F2,27= 3.766; P= 0.036). However, timolol did not produce a significant change in the accommodative response to positive or negative lenses or response AC/A ratios. Conclusions: We did not find that AC/A ratios in myopic Chinese children were elevated and therefore, it is unlikely that elevated AC/A ratios are responsible for the high levels of myopia that occur in Hong Kong. The finding that timolol reduced AC in the stable myopes suggests that the autonomic control of accommodative convergence in these children may be different from that in emmetropic children and those with progressing myopia. 相似文献
52.
Holly A Taylor Erin L McDonald Margaret Moon Mark T Hughes & Joseph A Carrese 《Medical education》2009,43(10):952-959
Context Previous research on ethical issues encountered by medical professionals in training and practice have presented the thematic content of the cases they encounter rather than the activities in which clinicians engage and in which they most often encounter ethical issues. We conducted a direct observation study of paediatrics residents and their preceptors seeing patients in an out‐patient general paediatrics clinic. Our objectives were to describe the everyday ethics‐related issues paediatrics residents encounter as they interact with patients. Our ultimate goal is to use this knowledge to enhance current efforts to teach ethics to paediatrics residents. Methods The study team directly observed paediatrics residents discussing patients with their faculty preceptors (19 half‐day sessions, 76 hours) in an out‐patient general paediatrics clinic located in an urban academic medical centre. Each interaction between resident and preceptor about a single patient was considered a case for further analysis. Results A total of 247 cases were recorded. Forty‐one of the cases were coded as having ethics‐related content. A constant comparative method of qualitative data analysis revealed that residents were most likely to encounter ethical issues when engaged in the following activities: (i) maintaining a therapeutic alliance with the caregiver (e.g. the parent); (ii) prioritising patient or family needs; (iii) adjusting to the power embodied by the role of doctors, and (iv) distinguishing suboptimal care from abuse or neglect. In addition, our findings indicate that it is through their efforts to maintain the therapeutic alliance with the caregivers of their patients that residents engage in and integrate three processes: developing their medical knowledge; adhering to professional norms, and balancing the power inherent in the doctor’s role with their responsibility to serve the patient’s interests. Conclusions Medical faculty tasked with teaching ethics to paediatrics residents can utilise the results of this project to better target and enhance their ethics education efforts directed at residents in the out‐patient setting. Future research could further examine and test these findings in other clinical settings (e.g. adult general medicine). 相似文献
53.
Sungil Jang Eun Jung Bak Minyoung Kim Jin Moon Kim Won-Yoon Chung Jeong-Heon Cha Yun-Jung Yoo 《Phytotherapy research : PTR》2010,24(7):964-968
To evaluate the inhibitory activity of wogonin against lipopolysaccharide (LPS)-induced bone resorption, we investigated the effect of wogonin on osteoclastogenesis induced by LPS. Wogonin inhibited LPS-induced osteoclastogenesis in co-cultures of mouse calvaria-derived osteoblasts and bone marrow-derived pre-osteoclasts. Wogonin also suppressed osteoclastogenesis in LPS-injected mouse calvaria. In osteoblasts, the upregulation of receptor activator of nuclear factor-κB (RANKL) expression and the downregulation of osteoprotegerin (OPG) expression by LPS were inhibited by wogonin. Wogonin and NS-398, a COX-2 inhibitor, suppressed LPS-stimulated PGE2 production in osteoblasts. NS-398 inhibited the effect of LPS on RANKL and OPG expression in osteoblasts. These results suggest that wogonin acts as an inhibitor of LPS-induced osteoclastogenesis through downregulation of RANKL and upregulation of OPG expression via blockage of PGE2 production. Based on these results, wogonin has potential for use as a therapeutic agent in bacteria-induced bone resorption. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
54.
The sperm penetration assay is an expensive, time-consuming test to assess male fertility in vitro. Although some investigators are enthusiastic in its application, others feel that it is not sensitive or specific enough to be used as part of the routine infertility evaluation. Indeed, this bioassay is not a faithful reproduction of in vivo conditions. However, if the SPA is abnormal, it is unlikely that sperm will fertilize a human ovum in vivo. Conversely, a normal SPA does not guarantee successful in vivo fertilization. No bioassay can be absolute in its predictive value, but false-negative results must be kept to a minimum for this bioassay to be of any clinical significance. Each laboratory performing the SPA should optimize the assay for sensitivity, reproducibility, and minimization of false-negative results and then establish normal and abnormal ranges of its own. If the limitations of the SPA are kept in mind, and if we employ it very selectively, it may still be useful. 相似文献
55.
W K Moon M H Han I O Kim M W Sung K H Chang S W Choo M C Han 《AJNR. American journal of neuroradiology》1995,16(4):997
We report a case of congenital fistula from ectopic accessory parotid gland to the cheek demonstrated by CT sialography and CT fistulography. The right parotid gland was abnormally located lateral to masseter muscle. The fistula was arising from an ectopic accessory parotid gland with ectopic duct positioned anterior to masseter muscle. CT sialography and CT fistulography were very helpful in the diagnosis and surgical planning. 相似文献
56.
A laparoscopic approach was used for penile revascularization in a patient with vasculogenic impotence to avoid the long abdominal incision which was traditionally required to harvest the inferior epigastric artery as a neoarterial source. Despite the time-consuming nature of laparoscopy, this procedure was as efficacious but less morbid and required less convalescence than open revascularization. Whether more patients may benefit from this procedure must be evaluated in further studies. 相似文献
57.
Recessive dystrophic epidermolysis bullosa (RDEB) is an uncommon and severe disorder characterised by trauma-induced blisters, intractable skin ulcers, scarring, milia, and nail dystrophy. We report the good result of both surgical release of fingers allowing spontaneous epithelisation without skin grafting and post-operative meticulous skin care without splinting, followed-up for one year. 相似文献
58.
We performed transurethral resections of the prostate in 100 patients under local anesthesia supplemented when appropriate by intravenous medication. In the first part of the study (40 patients) local anesthesia was infiltrated into the prostate transurethrally only, while in the second part (60 patients) infiltration was performed transurethrally and perineally. Prostate sizes ranged from 5 to 50 gm., and pain control was excellent in the majority of the patients, especially when perineal infiltration was added to the procedure. Of the patients 98 per cent said they would do it again, no patient required conversion to general anesthesia and there were no significant complications relating to the anesthesia. Local anesthesia with intravenous supplementation can be performed successfully in the majority of the patients with small to moderately sized prostate glands. 相似文献
59.
Proposed definition of a smokeless tobacco user based on “potential” nicotine consumption 总被引:1,自引:0,他引:1
Kathleen L. Schroeder Moon S. Chen Jr. Gregory R. Iaderosa Elbert D. Glover Elizabeth W. Edmundson 《Addictive behaviors》1988,13(4):395-400
This study examined and operationally defined "light," "moderate," and "heavy" users of smokeless tobacco according to the potential amounts of nicotine consumed per week from chewing tobacco and/or snuff products. Fifty adult male smokeless tobacco users ranging in ages from 18-85 were tested to determine nicotine content of smokeless tobacco products consumed. The smokeless tobacco products were blindly analyzed by gas chromatography to determine nicotine content. Mean nicotine yield per week was calculated by multiplying the number of cans and/or pouches used per week and placed on a normal probability distribution. The mean nicotine yielded 238 mg/wk and the categories emerged as "light" less than or equal to 87 mg/wk, "moderate" 88-388 mg/wk and "heavy" users greater than or equal to 389 mg/wk. Differences regarding type of user (light, moderate, heavy) were crossed tabbed with educational levels, years of smokeless tobacco use, age the habit was initiated, perception of harm and whether habit forming, and reason for using smokeless tobacco. 相似文献
60.
A randomized comparison of pre-and post-experimental design was used to examine the effects of a fall prevention exercise program (FPEP) on muscle strength, ankle flexibility, balance, instrumental activities of daily living (IADLs), and depression for the community-dwelling elderly in Korea. Twenty-two subjects were assigned to an experimental group and twenty-three to a control group. The experimental group participated in a 4-day-per week FPEP of 8 weeks duration, twice a week by direct instruction and twice a week with videotaped instruction by the program instructor at each senior center. The eight-week FPEP turned out to be significantly effective in enhancing muscle strength, ankle flexibility and balance, and in reducing depression, after intervention among community-dwelling elderly in Korea. IADLs, however, was not changed by the intervention. Further research with a larger sample and longer follow up period is needed to expand our understanding about the effects of FPEP. Future study is also recommended to differentiate between the effects of FPEP by direct instruction and by videotaped. 相似文献