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   8207篇
  免费   684篇
  国内免费   16篇
耳鼻咽喉   125篇
儿科学   258篇
妇产科学   134篇
基础医学   1186篇
口腔科学   193篇
临床医学   1136篇
内科学   1382篇
皮肤病学   82篇
神经病学   806篇
特种医学   341篇
外科学   975篇
综合类   121篇
现状与发展   1篇
一般理论   7篇
预防医学   905篇
眼科学   126篇
药学   604篇
中国医学   35篇
肿瘤学   490篇
  2022年   51篇
  2021年   119篇
  2020年   84篇
  2019年   138篇
  2018年   127篇
  2017年   115篇
  2016年   115篇
  2015年   178篇
  2014年   220篇
  2013年   346篇
  2012年   474篇
  2011年   504篇
  2010年   279篇
  2009年   287篇
  2008年   450篇
  2007年   503篇
  2006年   500篇
  2005年   529篇
  2004年   564篇
  2003年   525篇
  2002年   433篇
  2001年   120篇
  2000年   101篇
  1999年   115篇
  1998年   106篇
  1997年   96篇
  1996年   76篇
  1995年   88篇
  1994年   80篇
  1993年   65篇
  1992年   83篇
  1991年   78篇
  1990年   79篇
  1989年   80篇
  1988年   78篇
  1987年   73篇
  1986年   70篇
  1985年   70篇
  1984年   71篇
  1983年   60篇
  1982年   64篇
  1981年   65篇
  1980年   59篇
  1979年   41篇
  1978年   37篇
  1977年   43篇
  1976年   59篇
  1975年   36篇
  1974年   40篇
  1973年   38篇
排序方式: 共有8907条查询结果,搜索用时 15 毫秒
31.
32.
Objectives: Previous studies have been inconsistent with regard to the extent to which stress perception, rather than stressor exposure, predicts negative health symptoms. Because sex differences have been observed in all three of these variables, in this study the possibility that sex differences also exist in the relationships between them is investigated. Methods: Self‐report inventories of perceived stress, stressor exposure, and negative health symptoms were given to 107 young‐adult participants (65 females, 42 males). Results: Sex differences were observed in the associations among perceived stress, stressor exposure, and negative health symptom rates. Specifically, while higher perceived stress and higher stressor exposure rates independently predicted higher negative health symptoms rates in females, only higher stressor exposure rates independently predicted higher negative health symptoms in males. Indeed, unexpectedly, after controlling for exposure to stressors there was a trend towards higher perceived stress predicting lower negative health symptoms in males. Conclusions: While exposure to stress was a significant negative predictor of health for both sexes, perception of stress was predictive only for females. One implication of this finding is that different psychological models are needed to predict health symptoms in the two sexes. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
33.
The development and implementation of effective community support systems are goals of many public mental health authorities who are attempting to shift the focus and dollars for mental health services from inpatient to community care. This article presents the results of a survey which asked 90 community mental health agency case managers to assess the community support and residential needs of over 1400 of their clients. Medication monitoring and therapy were rated high priority needs. Psychosocial treatment, day and vocational activities also ranked high. Survey responses regarding residential services indicated a need for more supported and supervised options.The study reported was a collaborative effort by county and agency staff.  相似文献   
34.
Hispanics are a growing ethnic minority in the United States and one at significant risk for heart failure. Health-related quality of life (HRQL) is poor in individuals with heart failure, especially during and immediately following hospitalization. No prior research into the HRQL of Hispanics with heart failure was located. A sample of 80 individuals with heart failure, evenly divided by primary language and matched on functional status using the New York Heart Association classification system and age, was studied for 6 months following hospital discharge. Data on HRQL were collected using Spanish and English versions of the Minnesota Living with Heart Failure Questionnaire. Scores improved over time in both groups but significantly more so in the Hispanics when compared to the non-Hispanics. Group differences in HRQL could not be explained by demographics, clinical characteristics, treatment received, perceived support, or instrument response characteristics. Further exploration of this naturally occurring phenomenon may provide insight into how HRQL can be improved in the general heart failure population.  相似文献   
35.
OBJECTIVES: To assess laparoscopic training curriculums in US Obstetrics and Gynecology residency programs. METHODS: A list of E-mail addresses was obtained for the accredited Obstetrics and Gynecology residency programs in the US from the CREOG Directory of Obstetric-Gynecologic Residency Programs and Directors. An E-mail survey containing 8 questions regarding laparoscopy training was sent to all residency directors with current E-mail addresses. RESULTS: Seventy-four residency directors responded to the survey for a response rate of 41%. Residency programs from all sections of the US were included in the study. Results of the survey indicate that 69% of residency programs had implemented a formal laparoscopy training program. At least half of the program directors surveyed stated that lack of faculty time and funds were the main barriers to laparoscopic surgery training. Seventy-two percent of those surveyed thought that in the future the health-care industry would demand proof of competency in laparoscopy as standard of care. CONCLUSIONS: Most US Obstetrics and Gynecology residency programs have implemented a formal laparoscopy training curriculum, use more than one method to train their residents, and involve almost half of their faculty on average in training residents to perform laparoscopic surgery.  相似文献   
36.
David Goldberg  M Tan  M Dale Sarradet  Marsha Gordon 《Dermatologic surgery》2003,29(2):161-3; discussion 163-4
BACKGROUND: A nonablative 350-microsec, 585-nm, flashlamp pulsed dye laser is currently being used for the treatment of rhytides. OBJECTIVE: To analyze both clinical rhytid improvement and electron microscopic evidence of ultrastructural changes after treatment with a nonablative 350-microsec, 585-nm, flashlamp pulsed dye laser. RESULTS: At 6 months after two treatments, 40% of the treated subjects noted mild improvement in rhytid appearance. Nontreating physician evaluation revealed some degree of improvement in 50% of the treated subjects. Mild improvement in quality and texture of the skin was also reported by 50% of the subjects. Electron microscopic evaluation showed ultrastructural changes that are consistent with new collagen formation. CONCLUSION: Treatment with a nonablative 350-microsec, 585-nm, flashlamp pulsed dye laser can lead to both clinical and electron microscopic evidence of improvement in photo-damaged skin.  相似文献   
37.
The intraperitoneal mass most commonly encountered after blunt abdominal truama is a hematoma. However, one must also consider unusual bulky tumors that can have imaging characteristics similar to those of hematoma. The most typical of these neoplasms is lymphoma, but a desmoplastic small cell tumor also may be observed. The presentation and imaging findings of a desmoplastic small tumor are described.  相似文献   
38.
Forty-seven patients with frequently recurring genital herpes participated in one or more of five sequential trials of oral suppressive therapy with 200 mg of acyclovir three times daily from four to 12 months' duration. The prolonged use of acyclovir was extremely well tolerated, and treatment efficacy was sustained through successive studies. Recurrences in eight patients with repeated treatment "failures" were more effectively suppressed with higher doses of acyclovir. All patients experienced recurrent infections after the treatments were completed; however, the mean time to recurrence following each treatment period became progressively longer, and resumption of suppressive therapy was no longer warranted for ten patients. These data indicate the efficacy and safety of chronic suppressive therapy with acyclovir and the value of interrupting prolonged treatment to assess its further need.  相似文献   
39.
Summary The renal clearance of melphalan and the fraction unbound in plasma were determined after intravenous infusion of 5 mg/m2 over 5 min in nine patients with cancer to obtain information regarding the mechanism of renal handling of melphalan. Four of the patients underwent bone marrow transplantation and also received an IV dose of 220 mg/m2. Total melphalan clearance after the 5 mg/m2 dose ranged from 66.0 to 272 ml/min per m2; the percentage of the dose excreted unchanged in urine, from 2.5% to 92.8%; renal clearance, from 4.1 to 188 ml/min per m2; the fraction unbound in plasma, from 0.0598 to 0.460; and t1/2, from 39.4 to 84.3 min. Unbound melphalan clearance and renal clearance calculated from the unbound fraction in plasma for each patient ranged from 441 to 3356 ml/min per m2 and 15 to 961 ml/min per m2 respectively and were not related to serum albumin, serum creatinine or creatinine clearance. The percentage of the dose exctreted and melphalan renal clearance were not related to urine flow. There was evidence of active secretion of melphalan in the kidney an possible reabsorption. There were no significant paired differences in melphalan disposition between the high- and low-dose studies. Highly variable renal clearance involving active secretion may contribute in part to large interpatient differences in the total plasma clearance of melphalan in patients with cancer.This study was supported by a grant from The Queen Elizabeth Hospital Research Foundation  相似文献   
40.
Band-pass response properties of rat SI neurons   总被引:6,自引:0,他引:6  
Rats typically employ 4- to 12-Hz "whisking" movements of their vibrissae during tactile exploration. The intentional sampling of signals in this frequency range suggests that neural processing of tactile information may be differentially engaged in this bandwidth. We examined action potential responses in rat primary somatosensory cortex (SI) to a range of frequencies of vibrissa motion. Single vibrissae were mechanically deflected with 5-s pulse trains at rates /=3 Hz. In contrast with this low-pass feature of the response, several other characteristics of the response revealed bandpass response properties. While average evoked response amplitudes measured 0-35 ms after stimulus onset typically decreased with increasing frequency, the later components of the response (>15 ms post stimulus) were augmented at frequencies between 3 and 10 Hz. Further, during the steady state, both rate and temporal measures of neural activity, measured as total spike rate or vector strength (a measure of temporal fidelity of spike timing across cycles), showed peak signal values at 5-10 Hz. A minimal biophysical network model of SI layer IV, consisting of an excitatory and inhibitory neuron and thalamocortical input, captured the spike rate and vector strength band-pass characteristics. Further analyses in which specific elements were selectively removed from the model suggest that slow inhibitory influences give rise to the band-pass peak in temporal precision, while thalamocortical adaptation can account for the band-pass peak in spike rate. The presence of these band-pass characteristics may be a general property of thalamocortical circuits that lead rodents to target this frequency range with their whisking behavior.  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