全文获取类型
收费全文 | 5522篇 |
免费 | 459篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 37篇 |
儿科学 | 250篇 |
妇产科学 | 112篇 |
基础医学 | 709篇 |
口腔科学 | 98篇 |
临床医学 | 725篇 |
内科学 | 1307篇 |
皮肤病学 | 97篇 |
神经病学 | 576篇 |
特种医学 | 208篇 |
外国民族医学 | 2篇 |
外科学 | 802篇 |
综合类 | 93篇 |
一般理论 | 12篇 |
预防医学 | 471篇 |
眼科学 | 36篇 |
药学 | 210篇 |
中国医学 | 2篇 |
肿瘤学 | 244篇 |
出版年
2021年 | 80篇 |
2019年 | 47篇 |
2018年 | 59篇 |
2017年 | 44篇 |
2016年 | 57篇 |
2015年 | 86篇 |
2014年 | 112篇 |
2013年 | 153篇 |
2012年 | 242篇 |
2011年 | 232篇 |
2010年 | 129篇 |
2009年 | 103篇 |
2008年 | 209篇 |
2007年 | 209篇 |
2006年 | 221篇 |
2005年 | 244篇 |
2004年 | 236篇 |
2003年 | 195篇 |
2002年 | 234篇 |
2001年 | 192篇 |
2000年 | 177篇 |
1999年 | 165篇 |
1998年 | 50篇 |
1997年 | 49篇 |
1996年 | 58篇 |
1995年 | 44篇 |
1993年 | 47篇 |
1992年 | 155篇 |
1991年 | 143篇 |
1990年 | 152篇 |
1989年 | 149篇 |
1988年 | 114篇 |
1987年 | 117篇 |
1986年 | 107篇 |
1985年 | 92篇 |
1984年 | 89篇 |
1983年 | 60篇 |
1981年 | 39篇 |
1980年 | 43篇 |
1979年 | 64篇 |
1978年 | 66篇 |
1977年 | 53篇 |
1976年 | 59篇 |
1975年 | 55篇 |
1974年 | 67篇 |
1973年 | 54篇 |
1972年 | 48篇 |
1971年 | 59篇 |
1970年 | 55篇 |
1969年 | 55篇 |
排序方式: 共有5991条查询结果,搜索用时 9 毫秒
61.
Chondrocyte-to-osteocyte transformation in grafts of perichondrium-free epiphyseal cartilage 总被引:9,自引:0,他引:9
When perichondrium-free pieces of embryonic quail epiphyseal cartilage are incubated on the chorioallantoic membranes of chick embryos, 2 developmental changes are observed. First, most grafts develop a periosteum in which the osteoblasts and osteocytes are of donor, i.e., chondrocytic origin. No such periosteum is observed around explants of demineralized, inductive bone matrix. Second, the matrix surrounding some chondrocytes within the original graft became more bone-like with respect to staining pattern, birefringence and collagen morphology. We conclude that, under some conditions, the avian chondrocyte may in situ or subsequent to release from the cartilage lacuna synthesize a bone-like matrix and, in this sense, be thought to have undergone a "transformation" into an osteocytic or osteoblastic type of cell. 相似文献
62.
Following a summary of the relevant historical and legislative background, this article reviews the literature on: (i) rates of alcohol usage and problem drinking in Aboriginal populations; (ii) adverse effects of drinking; (iii) suggested causes of problem drinking among Aborigines; and (iv) treatment and preventive initiatives. The need to examine Aboriginal alcohol use in the wider context of socio-economic deprivation and rapid social change is emphasized. Key issues warranting further research attention are identified and, while recognizing the difficulties inherent in doing so, suggestions are made as to how the quality of research in the area might be raised. It is concluded that, without long-term planning and commitment of the necessary resources by government, little progress will be made in reducing the problems associated with Aboriginal use of alcohol. 相似文献
63.
When exposed to an unfamiliar and sudden noise, infant rodents may show an abrupt bradycardia, as part of a "fear-paralysis response". The response is enhanced by body movements restraint. To investigate if this reaction is seen in humans, 15 normal infants with a median age of 12 weeks were studied polygraphically. They were exposed to a 100-dB (A) white noise, while sleeping in REM sleep. Each infant was studied in both "unrestrained" and "restrained" conditions. Restraint of body movement was obtained by means of sand bags and tightly-binding bed sheets. During movement restraint, the infants had a significantly greater and earlier decrease in heart rate compared with during the unrestrained condition. No infant had a minimal heart rate less than 95 beats/min. The present observation raises questions about the possible unfavorable effects of tightly wrapped bed sheets around sleeping infants. 相似文献
64.
Regional odontodysplasia, a relatively rare developmental abnormality of the dental hard tissues, most often unilaterally and segmentally involves the anterior maxillary teeth of young females. Patients often have pulpal pathosis, periodontal manifestations, and irregularities of the eruption sequence of the affected teeth. The resultant reduced density of the enamel and dentin imparts a radiographic appearance of "ghosting" with correspondingly enlarged pulp chambers and canals. Etiology is uncertain; numerous local and systemic factors have been proposed. Treatment may sometimes be controversial, and timing of extractions and restorative procedures is critical. This case report illustrates the signs and symptoms of regional odontodysplasia, to aid clinicians in early recognition of the condition, to provide further evidence that a local circulatory disorder might be involved in its pathogenesis, and to illustrate treatment options that consider the patient's development and welfare. 相似文献
65.
BACKGROUND. Internship and residency are stressful experiences for physicians in training. Residency programs vary in their provision of supportive services for residents. METHODS. A random sample of 50% of the nation's family practice residency programs was surveyed to determine the prevalence of 19 support services, 10 of which were assessed a decade previously. Programs were also asked about on-call frequency, vacation benefits, and program size. RESULTS. Approximately 91% of the programs responded. The surveys indicated that residents were on call an average of once every four nights, a 10% decrease from a decade ago. The prevalence of three support services had increased over the last decade: seminars and speakers on the stresses and conflicts of being a physician, support groups for residents, and child care services. "Night-float" rotations and part-time residencies are the least offered support services of those studied. CONCLUSIONS. Support for family practice residents is increasing, yet in many cases remains inadequate. 相似文献
66.
H Dardik S M Berry A Dardik F Wolodiger J Pecoraro I M Ibrahim M Kahn B Sussman 《Journal of vascular surgery》1991,13(5):685-90; discussion 690-1
From November 1979 through December 1989, 210 distal arteriovenous fistulas were constructed as adjuncts to tibial and peroneal vascular reconstructive procedures in 203 patients threatened with limb loss. Two-year cumulative patency rates were calculated by grouping patients on the basis of changing indications in sequential time periods: group 1 (n = 61): 1979 to 1983, 18%; group 2 (n = 80): 1983 to 1986, 33%; group 3 (n = 69): 1986 to 1989, 44%. Although the therapeutic results observed in these groups are not statistically comparable, they show a perceptible trend. Postoperative arteriography showed that flow is prograde in the distal vessels beyond the distal arteriovenous fistula. Graft surveillance by duplex ultrasonography also confirmed that flow in the distal arteries is prograde and that "steal" does not occur. Peak systolic velocity (174 +/- 38 cm/sec) and mean velocity (92 +/- 23) flow rates are increased in grafts with patent distal arteriovenous fistulas compared to those bypasses with closed distal arteriovenous fistulas (p less than 0.01). There were no differences in the flow measurements for the arteries beyond the distal anastomoses and distal arteriovenous fistulas, confirming the prograde nature of the distal flow. In 22 patients analysis of graft and fistula patency by duplex sonography showed that one fourth of all grafts were patent without fistulas at 1 and 2 years after operation. Alternatively, 68% of patent grafts at 1 year had patent fistulas and 58% had patent fistulas at 2 years. We conclude that the distal arteriovenous fistula will increase graft flow and simultaneously prevent distal arterial overload without causing "steal." This technique should be considered whenever a prosthetic graft is necessary for crural reconstruction and only in selected instances of revascularization with autologous veins. 相似文献
67.
Pelvic inflammatory disease. Key treatment issues and options. 总被引:6,自引:0,他引:6
OBJECTIVE.--To examine available data regarding optimal antimicrobial therapy for pelvic inflammatory disease (PID) and to address selected treatment issues confronting clinicians caring for women with PID. DATA SOURCES.--Studies evaluated to help establish the Centers for Disease Control's 1989 Sexually Transmitted Diseases Treatment Guidelines and other reports published since 1985. A MEDLINE search of English-language literature was conducted using the indexing terms "pelvic inflammatory disease" or "pelvic infections" or "salpingitis" and "treatment". In addition, abstracts and bibliographies of articles and books were reviewed. STUDY SELECTION.--Studies were selected for detailed review if they evaluated the effectiveness of an antimicrobial regimen for treatment of PID. DATA EXTRACTION.--All studies were evaluated to determine the numbers of women treated and the percentage with clinical or microbiologic evidence of cure. DATA SYNTHESIS.--A variety of combination antimicrobial regimens are highly effective in providing clinical and microbiologic evidence of cure; few data are available to assess optimal therapy for prevention of late sequelae. Because PID is polymicrobial in cause, recommended antimicrobial regimens are broad-spectrum in coverage. CONCLUSIONS.--No single agent that provides sufficient coverage is currently available. Several combination regimens appear highly effective clinically even among women with tubo-ovarian abscess formation. Uncertainties regarding the effectiveness of antimicrobial therapy for prevention of late sequelae complicate decisions regarding the choice among regimens and the appropriateness of ambulatory treatment of women with PID. Pending better data, hospitalization should be strongly considered, where feasible, particularly for those women with PID desiring further childbearing. Sex partners of all women with PID should be treated. 相似文献
68.
Until the 1960s, the sexuality of people with mental retardation was handled by denial and suppression. The eugenics movement of 1880–1940 led to forced mass sterilization and the segregation of these members of our society. The civil rights movement and the sexual revolution were among the catalysts for change as was the move toward normalization and deinstitutionalization of people with mental retardation. In the last 25 years, parents and professionals have begun to work together to find ways to help mentally handicapped individuals to understand their sexuality and to engage in appropriate self-affirming sexual behaviors. We have established goals, guidelines, and curricula for sexuality education. We have trained parents and staff and developed policies for handling sensitive issues, such as sterilization and problematic sexual expression. The AIDS epidemic has provided new impetus for improving education and training in this emerging field.A.C.S.W.Private practice (as a consultant, lecturer, and trainer in sexuality and mental retardation). 相似文献
69.
During the past five years, there has been a sharp increase in the use of packed RBCs (PRBCs) and plasma products, whereas whole blood (WB) transfusions have steadily decreased. In order to determine whether plasma and its derivatives were being used to "reconstitute" whole blood from PRBCs, we performed a retrospective evaluation of all transfusion episodes in ten representative regional hospitals during a five-month period. Our results indicate that PRBCs were transfused 2.5 times more frequently than WB. Plasma products were administered with PRBCs less often than with WB: 14% of all PRBCs vs 24% of all WB units tranfused. The likelihood of a patient receiving plasma was found to correlate with the total amount of blood transfused and the frequency of transfusion. This study provides evidence that, at most, only a small percentage of PRBCs are given in conjunction with plasma as "reconstituted" WB. 相似文献
70.
Walsh BT Agras WS Devlin MJ Fairburn CG Wilson GT Kahn C Chally MK 《The American journal of psychiatry》2000,157(8):1332-1334
OBJECTIVE: This was an investigation of whether treatment with fluoxetine is useful for individuals with bulimia nervosa who do not respond to psychotherapy or relapse afterward. METHOD: Twenty-two patients with bulimia nervosa who had not responded to, or had relapsed following, a course of cognitive behavior therapy or interpersonal psychotherapy were randomly assigned to receive placebo (N=9) or fluoxetine (60 mg/day, N=13) for 8 weeks. RESULTS: The median frequency of binge eating in the previous 28 days declined from 22 to four episodes in the fluoxetine group but increased from 15 to 18 episodes in the placebo group. Similarly, purging frequency in the previous 28 days declined from 30 to six episodes in the fluoxetine group but increased from 15 to 38 episodes in the placebo group. CONCLUSIONS: Fluoxetine may be a useful intervention for patients with bulimia nervosa who have not responded adequately to psychological treatment. 相似文献