首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   16378篇
  免费   1106篇
  国内免费   31篇
耳鼻咽喉   118篇
儿科学   647篇
妇产科学   481篇
基础医学   2058篇
口腔科学   191篇
临床医学   2670篇
内科学   2794篇
皮肤病学   164篇
神经病学   1378篇
特种医学   268篇
外国民族医学   1篇
外科学   1176篇
综合类   568篇
一般理论   37篇
预防医学   2516篇
眼科学   311篇
药学   886篇
中国医学   8篇
肿瘤学   1243篇
  2023年   84篇
  2022年   130篇
  2021年   308篇
  2020年   205篇
  2019年   306篇
  2018年   320篇
  2017年   238篇
  2016年   311篇
  2015年   382篇
  2014年   480篇
  2013年   790篇
  2012年   1158篇
  2011年   1226篇
  2010年   574篇
  2009年   548篇
  2008年   1049篇
  2007年   1176篇
  2006年   1125篇
  2005年   1130篇
  2004年   1133篇
  2003年   1073篇
  2002年   1016篇
  2001年   126篇
  2000年   95篇
  1999年   139篇
  1998年   204篇
  1997年   190篇
  1996年   178篇
  1995年   168篇
  1994年   133篇
  1993年   116篇
  1992年   79篇
  1991年   72篇
  1990年   80篇
  1989年   72篇
  1988年   75篇
  1987年   50篇
  1986年   62篇
  1985年   61篇
  1984年   71篇
  1983年   72篇
  1982年   72篇
  1981年   86篇
  1980年   76篇
  1979年   63篇
  1978年   49篇
  1977年   48篇
  1976年   46篇
  1975年   25篇
  1974年   40篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
Melorheostosis is characterised radiologically by hyperostotic linear densities in bone. These densities have a peculiarly segmental distribution which does not correspond with the anatomical course of blood vessels or mixed nerve roots of the limbs. So far this distribution has lacked any valid explanation, although it has been suggested to be a developmental error as a result of an embryonic metameric disturbance. Inman and Saunders in 1944 described a sensory nerve supply to skeletal structures with sclerotomes representing the zones of the skeleton supplied by individual spinal sensory nerves. Radiographs of 30 cases from the Radiological Museum of the Institute of Orthopaedics, London, have been reviewed and an attempt has been made to correlate the sclerosing lesions with the sclerotomes. The investigation was handicapped by paucity of films and clinical information, but in 19 cases the skeletal abnormalities were considered to correspond with a single sclerotome or part thereof. These studies were convincing when films of an affected hand or foot were available. In the remaining 11 cases multiple sclerotomes appeared to be involved and the clinical manifestations were correspondingly more severe. It is proposed that melorheostosis may be the late result of a segmental sensory nerve lesion, to account for its sclerodermal distribution. The association with linear scleroderma is discussed, since it has been suggested that these cutaneous lesions are related to the same nerve segment. Eight cases showed para-articular ossification of soft tissues which may be related to involvement of a corresponding myotome.  相似文献   
83.
PURPOSE: In recent years, the incidence of cutaneous melanoma has increased more than that of any other cancer. Dacarbazine is considered the gold standard for treatment, having a response rate of 15% to 20%, but most responses are not sustained. Previously, we have shown that short exposure of primary cutaneous melanoma cells to dacarbazine resulted in the upregulation of interleukin-8 (IL-8) and vascular endothelial growth factor (VEGF). The purpose of the present study was to determine how long-term exposure of melanoma cells to dacarbazine would affect their tumorigenic and metastatic potential in vivo. MATERIALS AND METHODS: The primary cutaneous melanoma cell lines SB2 and MeWo were repeatedly exposed in vitro to increasing concentrations of dacarbazine, and dacarbazine-resistant cell lines SB2-D and MeWo-D were selected and examined for their ability to grow and metastasize in nude mice. RESULTS: The dacarbazine-resistant cell lines SB2-D and MeWo-D exhibited increased tumor growth and metastatic behavior in vivo. This increase could be explained by the activation of RAF, MEK, and ERK, which led to the upregulation of IL-8 and VEGF. More IL-8, VEGF, matrix metalloproteinase-2 (MMP-2), and microvessel density (CD-31) were found in tumors produced by SB2-D and MeWo-D in vivo than in those produced by their parental counterparts. No mutations were observed in BRAF. CONCLUSION: Our results have significant clinical implications. Treatment of melanoma patients with dacarbazine could select for a more aggressive melanoma phenotype. We propose that combination treatment with anti-VEGF/IL-8 or MEK inhibitors may potentiate the therapeutic effects of dacarbazine.  相似文献   
84.
OBJECTIVES: To explore associated biological outcomes and clarify the role of timing of exposure in the alcohol-breast cancer relationship.METHODS: In a population-based study of 4,575 women ages 35 to 64 years diagnosed with invasive breast cancer between 1994 and 1998 and 4,682 controls, we collected details of lifetime alcohol use and factors that could confound or modify the alcohol-breast cancer relationship. We used conditional logistic regression to compute the odds of breast cancer among drinkers relative to nondrinkers at all ages and at ages 35 to 49 and 50 to 64 years separately.RESULTS: Recent consumption (at reference age minus two) of >/=7 drinks per week was associated with increased risk [odds ratio (OR), 1.2; 95% CI, 1.01-1.3] and evidence of dose response was observed. Most of the excess was observed among women ages 50-64 years (OR 1.3; 95% CI, 1.1-1.6), although the test for age interaction was not statistically significant. Exposure later in life seemed more important than early exposure. Excess breast cancer associated with recent consumption was restricted to localized disease. When outcome was examined according to tumor hormone receptor status, highest risks were observed for estrogen receptor-positive/progesterone receptor-negative tumors (OR 1.6; 95% CI, 1.2-2.3).CONCLUSIONS: The effect of timing of alcohol exposure on breast cancer risk is complicated and will require additional study focused on this one issue. Further work is needed to explain how alcohol exposure, sex hormones, and tumor receptor status interact.  相似文献   
85.
86.
Human papillomavirus (HPV) subtypes 16 and 18 are sexually transmitted and have been associated with an increased incidence of several anogenital tumors. Although previous epidemiological studies have suggested that sexual behaviors such as an early age at first intercourse and larger numbers of sexual partners are also related to an increased risk of prostate cancer, seroepidemiological studies of these infectious agents in relation to prostate cancer have produced differing results. To further evaluate this potential relationship, we completed a population-based control study in King County, Washington. Middle-aged (40-64 years) men diagnosed with prostate cancer (n = 642) were ascertained through the Seattle-Puget Sound Surveillance, Epidemiology, and End Results cancer registry between January 1993 and December 1996. Controls (n = 570) of similar age were selected from the same population as the cases by random digit dialing. Overall, there was no association between serological evidence of prior HPV-16 (adjusted odds ratio, 1.06; 95% confidence interval, 0.71-1.57) or HPV-18 (adjusted odds ratio, 1.36; 95% confidence interval, 0.69-2.69) infection and the risk of prostate cancer. Analyses of clinical features demonstrated no relationship between HPV infection status and Gleason score, stage of disease, or a combined measure of disease aggressiveness. Our findings indicate that HPV-16 and HPV-18 are not associated with prostate cancer risk.  相似文献   
87.
Recombinant human relaxin as a cervical ripening agent   总被引:3,自引:0,他引:3  
Objective The aim of this study was to investigate the efficacy and safety of recombinant human relaxin (rhRIx) as a cervical ripening agent in women with an unfavourable cervix before induction of labour at term.
Design A multi-centre, double-blind, placebo-controlled trial performed in Edinburgh, Glasgow and Oxford. Women were treated with 0, 1, 2 or 4 mg of rhRIx in a gel vehicle administered intravaginally. Analysis of variance tests were performed on all continuous variables, and Cochran Mantel-Haenszel tests employed for all discrete variables.
Participants Ninety-six women at 37 to 42 weeks of gestation with a singleton pregnancy and a modified Bishop score of 4 were recruited.
Results There was no significant difference in the change in modified Bishop score between the four treatment groups. The lengths of the first and second stages of labour were similar in all 4 groups. PGE2 and oxytocin requirements were similar in all groups, as was the mode of delivery. There was no evidence that relaxin was absorbed systemically when given in this way.
Conclusion Recombinant human relaxin 1 to 4 mg, administered as an intravaginal gel, has no effect as a cervical ripening agent before induction of labour at term.  相似文献   
88.
This historical review of the literature highlights the struggles that American nurse-midwifery has undergone in defining itself to the medical profession. Because nurse-midwifery came into existence in this country close on the heels of the demise of traditional midwifery, it had many prejudices to overcome. For many years, nurse-midwifery allied itself with nursing to gain power and acceptance from physicians. Now, however, there is a move toward independence as nurse-midwives are more visible and the effectiveness and safety of their practice have been established.  相似文献   
89.
This study assesses the ability of plasma from women with pre-eclampsia to induce altered endothelial function in myometrial resistance vessels from normotensive women. Vessels from normotensive pregnant women (n= 7) were incubated with plasma from other pregnant women who were normotensive (n= 6)or had pre-eclampsia (n= 7). A wire myograph was used to test the endothelium-dependent relaxatory response to bradykinin of preconstricted vessels. The relaxation in vessels incubated with plasma from women with pre-eclampsia was markedly less than in vessels incubated with plasma from normotensive pregnant women (  P = 0.039  ). This supports the theory that a plasma-borne factor contributes to the endothelial changes seen in pre-eclampsia.  相似文献   
90.
OBJECTIVE: To test a quality improvement approach called COPE (Client-Oriented, Provider-Efficient services), for use in strengthening health systems and supporting Integrated Management of Child Health (IMCI) efforts. DESIGN: Pre- and post-intervention observations of client/provider interactions, facility audits, staff and client surveys, and focus groups to evaluate differences between eight COPE intervention and eight matched non-intervention facilities after a 15-month intervention in 2001. SETTING: Primary care clinics in Guinea and Kenya. STUDY PARTICIPANTS: Health care providers and child caregivers. INTERVENTIONS: Over 15 months, the intervention supported four COPE exercises at each intervention site, supported supervisor training in quality management, and organized minimal training in topics selected by site staff as areas where training was needed. MAIN OUTCOME MEASURES: Differences in staff's and child caregiver's knowledge, attitudes, and practices; differences in the quality of services provided. RESULTS: On almost every quality indicator (over 65 indicators), whether reported by staff, observed by evaluators, or reported by clients, the intervention sites performed statistically significantly better than control sites. INTERVENTION: sites were cleaner and more pleasant, with more respect and information for clients, and more privacy. Staff had better personal communication skills, better diagnostic skills, and prescribing practices and gave better home care instructions to carers. Clients in intervention sites were more informed and more satisfied, and their children had better immunization coverage than those in control sites. CONCLUSION: COPE is a simple process, yet our study confirms that it can have a very dramatic effect on the quality of services. This study demonstrated how all areas of quality can be addressed by empowering health care providers to take action by using COPE. We suggest that COPE can complement Integrated Management of Childhood Illness (IMCI) training and can help to achieve better health for children.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号