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   5539篇
  免费   471篇
  国内免费   68篇
耳鼻咽喉   84篇
儿科学   155篇
妇产科学   107篇
基础医学   616篇
口腔科学   254篇
临床医学   575篇
内科学   1151篇
皮肤病学   124篇
神经病学   348篇
特种医学   482篇
外国民族医学   1篇
外科学   772篇
综合类   140篇
一般理论   4篇
预防医学   366篇
眼科学   107篇
药学   317篇
中国医学   5篇
肿瘤学   470篇
  2018年   57篇
  2017年   45篇
  2016年   55篇
  2015年   56篇
  2014年   82篇
  2013年   119篇
  2012年   150篇
  2011年   172篇
  2010年   122篇
  2009年   112篇
  2008年   177篇
  2007年   239篇
  2006年   218篇
  2005年   198篇
  2004年   177篇
  2003年   192篇
  2002年   189篇
  2001年   192篇
  2000年   193篇
  1999年   166篇
  1998年   107篇
  1997年   106篇
  1996年   96篇
  1995年   105篇
  1994年   74篇
  1993年   74篇
  1992年   139篇
  1991年   157篇
  1990年   132篇
  1989年   158篇
  1988年   165篇
  1987年   156篇
  1986年   135篇
  1985年   156篇
  1984年   99篇
  1983年   100篇
  1982年   78篇
  1981年   67篇
  1980年   60篇
  1979年   92篇
  1978年   75篇
  1977年   69篇
  1976年   79篇
  1975年   53篇
  1974年   55篇
  1973年   58篇
  1972年   52篇
  1971年   52篇
  1970年   50篇
  1969年   45篇
排序方式: 共有6078条查询结果,搜索用时 31 毫秒
91.
To evaluate the role of the volume of blood cultured in the detection of clinically important bacteremia and fungemia in adults, we evaluated the yield and speed of detection of microorganisms from 5,317 paired 2- and 5-ml samples of blood. The same kind of medium (supplemented peptone broth with 0.03% sodium polyanetholsulfonate) and atmosphere of incubation (open venting units) were used for all blood cultures. Only adequately filled (less than or equal to 80% of stated volume) sets (20-ml tube and 50-ml bottle) were compared statistically. Significantly more bacteria (p less than 0.01), Pseudomonas spp. In particular (P less than 0.05), were isolated from the 5-ml samples of blood. We conclude that the volume of blood cultured is a critical factor in the detection of septicemia. Consequently, valid evaluation of other factors influencing the detection of septicemia must be based on comparisons in which equal volumes of blood are cultured.  相似文献   
92.
93.
We report a restainin method for restoring fluorescence in paraffin-embedded tissue sections previously treated with the indirect immunofluorescence technique. Antisera to gastrin and group II pepsinogens were used. Fluorescence was restored in completely faded sections retrived from storage files, as well as in sections that had faded partially either with exposure to fluorescence microscope illumination or after counterstaining with hematoxylin and eosin.  相似文献   
94.
BACKGROUND. There is a lack of consensus among cardiologists about the potential benefit of thrombolytic therapy for suspected acute myocardial infarction in older patients. To investigate this issue, we constructed a decision-analytic model for patients 75 years of age or older who present with ST-segment elevation within six hours of the onset of symptoms suggesting acute myocardial infarction. METHODS. The variables incorporated in this model were the probability that the patient has an acute myocardial infarction, the probability of in-hospital death among patients with acute myocardial infarction who do not receive thrombolytic therapy, the probability of a fatal or incapacitating complication resulting from thrombolytic therapy, and the expected relative reduction in the risk of death associated with thrombolytic therapy in patients with acute myocardial infarction. Our analyses were based primarily on the use of streptokinase as the thrombolytic agent. RESULTS. Given our base-line assumptions, the probability of dying in the hospital was 21.4 percent if thrombolytic therapy was given and 24.4 percent if it was not given. In one-way sensitivity analyses, thrombolytic therapy decreased the risk of dying if the probability that the patient had an acute myocardial infarction was assumed to be greater than 9 percent, if the probability of dying in the hospital after an acute myocardial infarction without thrombolytic therapy was assumed to be greater than 3 percent, if the rate of fatal or incapacitating complications due to thrombolytic therapy was assumed to be 4 percent or less, or if the relative reduction in the risk of death associated with thrombolytic therapy was assumed to be greater than 1 percent. On the basis of our base-line assumptions, our estimate of the cost effectiveness of streptokinase therapy (the cost per year of life saved) for an 80-year-old patient with suspected acute myocardial infarction was $21,200. For a wide range of assumptions about risks, benefits, and costs, the cost per year of life saved remained less than $55,000. CONCLUSIONS. Within the limitations imposed by the assumptions used in our analysis, thrombolytic therapy with streptokinase was found to be a beneficial and cost-effective treatment for suspected acute myocardial infarction in elderly patients in a wide variety of clinical circumstances.  相似文献   
95.
Lung carcinoids occur sporadically and rarely in association with multiple endocrine neoplasia type 1 (MEN1). There are no well defined genetic abnormalities known to occur in these tumors. We studied 11 sporadic lung carcinoids for loss of heterozygosity (LOH) at the locus of the MEN1 gene on chromosome 11q13, and for mutations of the MEN1 gene using dideoxy fingerprinting. Additionally, a lung carcinoid from a MEN1 patient was studied. In four of 11 (36%) sporadic tumors, both copies of the MEN1 gene were inactivated. All four tumors showed the presence of a MEN1 gene mutation and loss of the other allele. Observed mutations included a 1 bp insertion, a 1 bp deletion, a 13 bp deletion and a single nucleotide substitution affecting a donor splice site. Each mutation predicts truncation or potentially complete loss of menin. The remaining seven tumors showed neither the presence of a MEN1 gene mutation nor 11q13 LOH. The tumor from the MEN1 patient showed LOH at chromosome 11q13 and a complex germline MEN1 gene mutation. The data implicate the MEN1 gene in the pathogenesis of sporadic lung carcinoids, representing the first defined genetic alteration in these tumors.   相似文献   
96.
We have found that the above activities are facilitated by utilizing a computerized filing program. The computer formal provides quick, concise reports and statistical data analysis. The formation catalogued can be easily analysis. The information catalogued can be easily categorized and analyzed. The time invested in organizational meetings concerning committee membership, guideline review and creating an efficient incident coding scheme was essential to the success of the project. Problems seem to arise when several different departments share a common space for different activities. For example, medication room sanitation throughout the hospital was suboptimal probably related to the fact that Nursing, Pharmacy and General Stores all utilized the area. No individual department felt it was their sole responsibility to ensure appropriate sanitation. Through the efforts of the task force, we were able to facilitate cooperation among the departments with each doing their share. As a result, medication rooms are now cleaner, neater and therefore safer. Additional incidents have been corrected since the original tabulation of this report. A priority goal is to facilitate corrective action in a more timely manner. It is critical that surveys should not be intended to be "white glove inspections" with criticisms placed on specific departments. This can be accomplished by informing department managers of the intent of the surveys and by allowing staff to participate in all activities. In addition, the support and cooperation of administration is a major factor in the potential success of a program of this nature. As a result of the interdisciplinary team approach, the general safety environment for patients, visitors, employees and volunteers has significantly been improved at our institution.  相似文献   
97.
The purpose of this discussion has been to bring to the attention of physicians the fact that all instances of etiologically undefined persistent fever are not associated with potentially serious or life-threatening organic disease, regardless of the height of the temperature. As has been pointed out, many patients with FUO clearly have disorders that are clinically benign, and the cause of these disorders is defined much more frequently on the basis of information obtained from a detailed historic inquiry than on the basis of findings made during the most meticulous physical examination and extensive laboratory studies. These individuals are usually seen first in an outpatient setting and seldom, if ever, require hospitalization because the cause of their FUO can, with uncommon exceptions, be identified as a physiologic or emotional dysfunction, a reaction to a drug or a chemical, or a disorder that is genetically determined. Failure to recognize that even a high elevation of the temperature can represent a clinically benign situation may lead to unnecessary hospitalization, during which the many investigations that are usually carried out may serve only to reinforce the patient's concern about a serious disease. It is most important for both patients and physicians to be aware that temperature, like all other physiologic and chemical measurements in humans, is expressed by a range of values and that a temperature of 98.6 degrees F is not normal for all persons. It must also be appreciated that "normal" temperature varies with age. The newborn infant may develop high-grade fever in the absence of disease because of marked instability of the vasomotor system.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
98.
Primary sphincter repair in anorectal trauma   总被引:2,自引:1,他引:1  
Two patients who sustained severe anorectal trauma from "fist fornication" were treated by irrigation, colostomy, drainage, antibiotics, and primary repair of the rectum and anal sphincters without complications. Both had complete return of continence. Primary sphincter repair is advocated for these and similar anorectal injuries.  相似文献   
99.
Congenital coxa vara. A retrospective review   总被引:1,自引:0,他引:1  
Forty-two cases of coxa vara were retrospectively reviewed. All 42 cases were classified based on their history and roentgenographic appearance. Twenty-two cases of true congenital coxa vara were identified and are the primary focus of this review. In this study we have introduced the Hilgenreiner epiphyseal (HE) angle as measured on standard AP roentgenograms of the hip. Retrospectively, this angle was measured to aid in deciding candidacy for surgery, as well as a means of determining the amount of surgical correction necessary to prevent a recurrence of the deformity. The indication for surgery should be an HE angle of greater than 60 degrees. HE angles of less than 60 degrees and greater than 45 degrees represent a "gray zone" and should be observed. HE angles of less than 45 degrees will generally correct spontaneously without surgery.  相似文献   
100.

Health agencies call for the immediate mobilization of existing interventions in response to numerous child and family mental health concerns that have arisen as result of the COVID-19 pandemic. Answering this call, this pilot study describes the rapid, full-scale change from a primarily clinic-based Parent–Child Interaction Therapy (PCIT) model to a virtual service model (i.e., I-PCIT) in an academic and community-based program in Miami, Florida. First, we describe the virtual service training model our program developed and its implementation with 17 therapists (MAge?=?32.35, 88.2% female, 47.1% Hispanic) to enable our clinic to shift from providing virtual services to a small portion of the families served (29.1%) to all of the families served. Second, we examine the effect of I-PCIT on child and caregiver outcomes during the 2-month stay-at-home period between March 16, 2020, and May 16, 2020, in 86 families (MChildAge?=?4.75, 71% Hispanic). Due to the rapid nature of the current study, all active participants were transferred to virtual services, and therefore there was no comparison or control group, and outcomes represent the most recently available scores and not treatment completion. Results reveal that I-PCIT reduced child externalizing and internalizing problems and caregiver stress, and increased parenting skills and child compliance with medium to large effects even in the midst of the COVID-19 pandemic. Finally, the study examined components of our virtual service training model associated with the greatest improvements in child and caregiver outcomes. Preliminary findings revealed that locally and collaboratively developed strategies (e.g., online communities of practice, training videos and guides) had the strongest association with child and caregiver outcomes. Implications for virtual service delivery, implementation, and practice in the midst of the COVID-19 pandemic are discussed.

  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