全文获取类型
收费全文 | 2680篇 |
免费 | 333篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 13篇 |
儿科学 | 86篇 |
妇产科学 | 47篇 |
基础医学 | 326篇 |
口腔科学 | 46篇 |
临床医学 | 306篇 |
内科学 | 438篇 |
皮肤病学 | 82篇 |
神经病学 | 95篇 |
特种医学 | 134篇 |
外科学 | 532篇 |
综合类 | 139篇 |
一般理论 | 3篇 |
预防医学 | 332篇 |
眼科学 | 74篇 |
药学 | 251篇 |
中国医学 | 3篇 |
肿瘤学 | 114篇 |
出版年
2021年 | 38篇 |
2020年 | 26篇 |
2017年 | 30篇 |
2015年 | 42篇 |
2014年 | 63篇 |
2013年 | 71篇 |
2012年 | 105篇 |
2011年 | 87篇 |
2010年 | 58篇 |
2009年 | 77篇 |
2008年 | 77篇 |
2007年 | 106篇 |
2006年 | 102篇 |
2005年 | 88篇 |
2004年 | 80篇 |
2003年 | 91篇 |
2002年 | 82篇 |
2001年 | 81篇 |
2000年 | 72篇 |
1999年 | 71篇 |
1998年 | 58篇 |
1997年 | 34篇 |
1996年 | 49篇 |
1994年 | 44篇 |
1992年 | 73篇 |
1991年 | 67篇 |
1990年 | 58篇 |
1989年 | 65篇 |
1988年 | 61篇 |
1987年 | 65篇 |
1986年 | 52篇 |
1985年 | 50篇 |
1984年 | 59篇 |
1983年 | 33篇 |
1982年 | 33篇 |
1981年 | 30篇 |
1980年 | 45篇 |
1979年 | 52篇 |
1978年 | 50篇 |
1977年 | 33篇 |
1976年 | 29篇 |
1975年 | 40篇 |
1974年 | 34篇 |
1973年 | 36篇 |
1972年 | 37篇 |
1970年 | 33篇 |
1969年 | 30篇 |
1968年 | 25篇 |
1967年 | 24篇 |
1966年 | 29篇 |
排序方式: 共有3021条查询结果,搜索用时 15 毫秒
991.
Individuals at increased risk of developing breast cancer due to their family history of the disease face a number of uncertainties. Personal cancer risk estimates are imprecise and current methods for early detection or prevention are not 100% effective. It is therefore not surprising that adverse psychosocial outcomes have been described within this population. Research attempting to predict the incidence of distress and dysfunction in individuals at increased risk of cancer has been largely a-theoretical and has overlooked a number of potentially important predictive variables. In particular, the influence of personal experience of cancer through involvement with affected relatives has been neglected. There are strong theoretical grounds for hypothesising that dimensions of personal experience may influence response to cancer risk. This paper discusses the potential impact of personal experience on risk perception, illness representations and decision-making. Systematic research in this area may improve predictions of outcome of cancer genetic counselling and inform the clinical process. 相似文献
992.
Schilling BK Stone MH Utter A Kearney JT Johnson M Coglianese R Smith L O'Bryant HS Fry AC Starks M Keith R Stone ME 《Medicine and science in sports and exercise》2001,33(2):183-188
PURPOSE: Long-term safety of creatine supplementation has been questioned. This retrospective study was performed to examine markers related to health, the incidence of reported side effects and the perceived training benefits in athletes supplementing with creatine monohydrate. METHODS: Twenty-six athletes (18 M and 8 F, 24.7 +/- 9.2 y; 82.4 +/- 20.0 kg; 176.5 +/- 8.8 cm) from various sports were used as subjects. Blood was collected between 7:00 and 8:30 a.m. after a 12-h fast. Standard clinical examination was performed for CBC and 27 blood chemistries. Testosterone, cortisol, and growth hormone were analyzed using an ELISA. Subjects answered a questionnaire on dietary habits, creatine supplementation, medical history, training history, and perceived effects of supplementation. Body mass was measured using a medical scale, body composition was estimated using skinfolds, and resting heart rate and blood pressure were recorded. Subjects were grouped by supplementation length or no use: Gp1 (control) = no use (N = 7; 3 F, 4 M); Gp2 = 0.8-1.0 yr (N = 9; 2 F, 7 M); and Gp3 = 1(+) (N = 10; 3 F, 7 M). RESULTS: Creatine supplementation ranged from 0.8--4 yr. Mean loading dose for Gp2 and Gp3 was 13.7 +/- 10.0 and the maintenance dose was 9.7 +/- 5.7 g.d(-)1. Group differences were analyzed using one-way ANOVA. CONCLUSIONS: Expected gender differences were observed. Of the comparisons made among supplementation groups, only two differences for creatinine and total protein (P < 0.05) were noted. All group means fell within normal clinical ranges. There were no differences in the reported incidence of muscle injury, cramps, or other side effects. These data suggest that long-term creatine supplementation does not result in adverse health effects. 相似文献
993.
Daouti S Li WH Qian H Huang KS Holmgren J Levin W Reik L McGady DL Gillespie P Perrotta A Bian H Reidhaar-Olson JF Bliss SA Olivier AR Sergi JA Fry D Danho W Ritland S Fotouhi N Heimbrook D Niu H 《Cancer research》2008,68(4):1162-1169
The phosphatase of regenerating liver (PRL) family, a unique class of oncogenic phosphatases, consists of three members: PRL-1, PRL-2, and PRL-3. Aberrant overexpression of PRL-3 has been found in multiple solid tumor types. Ectopic expression of PRLs in cells induces transformation, increases mobility and invasiveness, and forms experimental metastases in mice. We have now shown that small interfering RNA-mediated depletion of PRL expression in cancer cells results in the down-regulation of p130Cas phosphorylation and expression and prevents tumor cell anchorage-independent growth in soft agar. We have also identified a small molecule, 7-amino-2-phenyl-5H-thieno[3,2-c]pyridin-4-one (thienopyridone), which potently and selectively inhibits all three PRLs but not other phosphatases in vitro. The thienopyridone showed significant inhibition of tumor cell anchorage-independent growth in soft agar, induction of the p130Cas cleavage, and anoikis, a type of apoptosis that can be induced by anticancer agents via disruption of cell-matrix interaction. Unlike etoposide, thienopyridone-induced p130Cas cleavage and apoptosis were not associated with increased levels of p53 and phospho-p53 (Ser(15)), a hallmark of genotoxic drug-induced p53 pathway activation. This is the first report of a potent selective PRL inhibitor that suppresses tumor cell three-dimensional growth by a novel mechanism involving p130Cas cleavage. This study reveals a new insight into the role of PRL-3 in priming tumor progression and shows that PRL may represent an attractive target for therapeutic intervention in cancer. 相似文献
994.
For love or money? An exploratory study of why injecting drug users participate in research 总被引:1,自引:0,他引:1
Aims. To examine injecting drug user (IDU) motivations as research participants.
Design. Convenience sampling facilitated by recruitment notices distributed through needle and syringe programmes (NSPs), and snowballing within peer networks.
Setting. NSPs in six suburbs throughout the Melbourne metropolitan area.
Participants. One hundred and fifty-four current IDUs. The mean age was 28 years, 62% were male, and 80% nominated heroin as preferred drug.
Measurements. Interviewer-administered survey including questions about socio-demographics, drug use and main reasons for participating in research.
Findings. IDU research participation reasons were consistent with motivational themes such as economic gain (46%), expression of citizenship (38%), altruism (19%), personal satisfaction (17%), drug user activism (16%) and seeking information or assistance (5%). Most respondents (58%) cited reasons where the primary beneficiaries of participation were other individuals or groups (citizenship, altruism, drug user activism) or both self and others.
Conclusions. IDU motivations for research involvement appear to be multi-dimensional, rarely motivated by economic gain alone, and not necessarily defined by direct benefits or gains to themselves. These findings are relevant to the question of IDU research payment ethics. 相似文献
995.
Psoriasis can be provoked or exacerbated by a variety of different environmental factors, particularly infections and drugs. Strong evidence exists for the induction of guttate psoriasis by a preceding tonsillar Streptococcus pyogenes infection, whereas disease exacerbation has been linked with skin and/or gut colonization by Staphylococcus aureus, Malassezia, and Candida albicans. The role, if any, of viruses (papillomaviruses, HIV, and endogenous retroviruses) present in lesional skin is at present unknown. The use of various drugs, such as lithium, β-blockers, antimalarial agents, nonsteroidal anti-inflammatory drugs, and angiotensin-converting enzyme inhibitors, has also been associated with induction or worsening of disease in psoriatic patients. 相似文献
996.
France EK Smith-Ray R McClure D Hambidge S Xu S Yamasaki K Shay D Weintraub E Fry AM Black SB Shinefield HR Mullooly JP Jackson LA 《Archives of pediatrics & adolescent medicine》2006,160(12):1277-1283
OBJECTIVE: To determine whether influenza vaccination of pregnant women prevents visits for respiratory illness in their infants born during the influenza season. DESIGN: Retrospective matched cohort study. SETTING: Four managed care organizations in the United States. Patients A total of 41 129 infants (3160 and 37 969 born to vaccinated and unvaccinated mothers, respectively) born between 1995 and 2001. Main Exposure Maternal influenza vaccination. Infants were considered exposed if their gestational age at birth was at least 30 weeks, if the time from maternal vaccination to birth was at least 28 days, and if they were exposed to at least 14 days of the influenza season. MAIN OUTCOME MEASURES: Incidence of acute respiratory illnesses (outpatient, emergency department, and inpatient settings combined) and incident rate ratios (IRRs) for infants exposed and unexposed to maternal vaccination during the following 4 periods: peak influenza, respiratory syncytial virus predominant, periseasonal, and summer weeks. The time to the first acute respiratory illness during peak influenza weeks was also assessed. RESULTS: During the peak influenza weeks, infant visit rates were 15.4 and 17.1 per 100 person-months for exposed and unexposed infants, respectively (IRR, 0.90; 95% confidence interval, 0.80-1.02). Adjusted IRRs for the 4 periods found a protective effect of infant female sex, whereas Medicaid status and maternal high-risk status increased infant visit rates. Maternal influenza vaccination did not reduce visit rates during any of the 4 time periods (IRR for peak influenza season, 0.96; 95% confidence interval, 0.86-1.07) and did not delay the onset of first respiratory illness. CONCLUSION: We were unable to demonstrate that maternal influenza vaccination reduces respiratory illness visit rates among their infants. 相似文献
997.
R G Turnbull D C Taylor Y N Hsiang A J Salvian S Nanji G O'Hanley D L Doyle P D Fry 《Canadian journal of surgery》2000,43(2):105-111
OBJECTIVES: To assess patient waiting times for vascular surgery and to determine if complications of the disease develop while the patients are awaiting surgery. DESIGN: Prospective cohort study. SETTING: A university-affiliated tertiary care institution. PATIENTS: All 554 patients who underwent scheduled vascular surgical procedures between April 1995 and October 1996. OUTCOME MEASURES: A literature review carried out to develop guidelines for acceptable waiting times for surgery associated with various vascular disorders based on their natural history (benchmark target); actual waiting times, defined as the interval from the date each patient was booked for surgery to the date of admission to hospital for the procedure; the proportion of patients admitted within the benchmark targets; and whether prolonged waiting time placed patients at risk for complications of their disease. RESULTS: Of the 554 patients, 382 (69%) were admitted within the benchmark waiting times. Of 84 patients having an abdominal aortic aneurysm, the aneurysm ruptured during the waiting period in 6, and 4 of them died, for a complication rate of 7% and a death rate of 5%. Two of the 6 aneurysms ruptured after the patient had waited longer than the target time. Three of 100 patients with symptomatic carotid artery stenosis awaiting admission for carotid endarterectomy suffered ischemic stroke, for a 3% complication rate; all had waited longer than the target period. One patient suffered occlusion of a femoropopliteal bypass graft while awaiting revision of a stenosed bypass graft. CONCLUSIONS: This study suggests that although most patients are admitted for operation within the benchmark time, one-third are admitted late and may suffer serious complications of their disease while awaiting admission for the procedure. 相似文献
998.
999.
PURPOSE: There have been 49 cases of adenosquamous carcinoma of the colon, rectum, and anus reported in the English literature. We have reviewed 145 cases of adenosquamous carcinoma to better define epidemiologic and survival characteristics of this extremely rare colon carcinoma. METHODS: The National Cancer Institute's Surveillance, Epidemiology, and End Results program public use CD-ROM file for the years 1973 through 1992 were reviewed. This represents approximately 9.5 percent of the United States population. Adenosquamous carcinomas arising in the colon, rectum, and anus were identified using the International Classification of Diseases-O codes. The Astler-Coller tumor classification was used for staging. Two-tailed Student'st-test, Mantel-Haenszel chi-squared tests, and generalized Wilcoxon's tests were used for comparisons of means, proportions, and actuarial survival rates, respectively. Survival curves were calculated by the Kaplan-Meier method. RESULTS: One hundred forty-five cases of adenosquamous carcinoma were identified, representing 0.06 percent of all colorectal malignancies. The mean age of patients was 67 years. Eighty-four percent of patients were Caucasians, 15 percent were Afro-Americans, and 1 percent were other races. Afro-Americans were diagnosed at a significantly younger age (median age, 62 years;P=0.03). Fifty-three percent of the carcinomas were located in the sigmoid colon, rectum, and anus, 28 percent in the right colon, and the rest in the middle segment. Seventy-four percent of distal cases were staged A through C, compared with 44 percent of proximal cases. Patients with adenosquamous carcinoma of the sigmoid colon, rectum, and anus survived longer than all other patients (P=0.001). Patients with adenosquamous carcinoma Stages A and B1 had survival rates similar to patients with comparably staged adenocarcinomas. Fifty percent of the patients, including most of the patients with D stage, died in the first year. Patients with Stages B2, C, and D adenosquamous carcinomas had a significantly shorter survival than the comparably staged adenocarcinomas (P0.02). The overall adjusted five-year survival rate was 30.7 percent. In those patients who survived more than 24 months, the five-year survival was 84 percent. CONCLUSIONS: The survival rates for patients with adenosquamous carcinoma Stages A and B1 are similar to patients with comparably staged colorectal adenocarcinomas. However, we found that patients with colorectal and anal adenosquamous carcinomas staged B2 through D have significantly poorer survival than patients with comparably staged adenocarcinomas, supporting the previous reports of a poor prognosis associated with adenosquamous carcinomas. 相似文献
1000.
J. W. Wright M.Sc. M.R.C.P. D. E. Fry B.Sc. Julius Merry M.D. F.R.C.Psych D.P.M. Vincent Marks M.A. D.M. F.R.C.P. F.R.C.Path. 《Addiction (Abingdon, England)》1976,71(3):211-215
Hypothalamic-pituitary-gonadal function was investigated in a group of 13 actively drinking chronic alcoholics. In a high proportion (46 per cent) of the patients basal plasma luteinising hormone (LH) levels were elevated and these patients showed an exaggerated plasma LH response to 100 μg LHRF. Plasma levels of 17β-hydroxy-androgens were normal in all subjects. Liver damage did not appear to explain the biochemical findings which may, however, be relevant to sexual and reproductive function in chronic alcoholic patients. 相似文献