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   2019篇
  免费   303篇
  国内免费   39篇
耳鼻咽喉   17篇
儿科学   113篇
妇产科学   27篇
基础医学   153篇
口腔科学   27篇
临床医学   311篇
内科学   615篇
皮肤病学   61篇
神经病学   187篇
特种医学   312篇
外国民族医学   5篇
外科学   205篇
综合类   31篇
预防医学   82篇
眼科学   21篇
药学   108篇
中国医学   1篇
肿瘤学   85篇
  2023年   53篇
  2022年   14篇
  2021年   34篇
  2020年   94篇
  2019年   21篇
  2018年   93篇
  2017年   77篇
  2016年   73篇
  2015年   65篇
  2014年   100篇
  2013年   120篇
  2012年   72篇
  2011年   54篇
  2010年   87篇
  2009年   118篇
  2008年   46篇
  2007年   58篇
  2006年   51篇
  2005年   32篇
  2004年   22篇
  2003年   17篇
  2002年   19篇
  2001年   41篇
  2000年   24篇
  1999年   37篇
  1998年   83篇
  1997年   97篇
  1996年   81篇
  1995年   73篇
  1994年   49篇
  1993年   55篇
  1992年   40篇
  1991年   20篇
  1990年   38篇
  1989年   61篇
  1988年   49篇
  1987年   32篇
  1986年   24篇
  1985年   25篇
  1984年   23篇
  1983年   13篇
  1982年   16篇
  1981年   16篇
  1980年   14篇
  1979年   10篇
  1978年   13篇
  1977年   10篇
  1976年   13篇
  1975年   9篇
  1971年   9篇
排序方式: 共有2361条查询结果,搜索用时 0 毫秒
131.
132.
133.
134.
OBJECTIVE: This report presents selected prevalence estimates for children ages 4-17 years with difficulties in emotions, concentration, behavior, or being able to get along with others using data from the 2001, 2002, and 2003 National Health Interview Surveys (NHIS). METHODS: Data for the U.S. civilian noninstitutionalized population were collected using computer-assisted personal interviews (CAPI). In 2001, a total of 10,367 interviews were completed about sample children ages 4-17 years by the member of the household most knowledgeable about the child's health. The number of completed interviews about sample children ages 4-17 years was 9,512 in 2002 and 9,399 in 2003. Questions on children's emotional and behavioral difficulties from the Strengths and Difficulties Questionnaire (SDQ) were first asked in the NHIS in 2001. SUDAAN software was used to tabulate statistics shown in this report. RESULTS: In 2001, 2002, and 2003, approximately 5% of U.S. children ages 4-17 years had emotional or behavioral difficulties, and for approximately 80% of these children, there was an impact on their functioning. Children with difficulties in emotions, concentration, behavior, or being able to get along with others varied by sex, age, race, family structure, poverty status, and health insurance status. About 50% of these children were upset or distressed by their emotional or behavioral difficulties, and about 80% had difficulties that impacted their family life, friendships, learning, or leisure activities.  相似文献   
135.
Summary Background Preclinical results in rats have demonstrated anxiolytic–like effects of a tryptic bovine S1–casein hydrolysate. Aim of the study We investigated the putative effects of this tryptic hydrolysate on systolic (SBP), diastolic (DBP) blood pressures, heart rate (HR) values and plasma cortisol concentrations (CC) in human healthy volunteers facing successive stress situations. Methods The subjects were (double blind) randomly allocated to ingest three times, 12 hours apart, two capsules containing either 200 mg of S1–casein hydrolysate (TS) or bovine skimmed milk powder as a placebo (CS). On the morning of the test day, a first blood sample for baseline measurement of CC was taken before the subjects were submitted to the Stroop test (ST) and, after a 30–min rest, to a Cold Pressor test (CPT). SBP, DBP, and HR were continuously recorded for 5 min before the ST and during each stress situation. A second blood sample was taken 15 min after the end of the CPT condition. Results ST and ST + CPT combined test situations increased SBP, DBP and HR. The significant Treatment × SBP and Treatment × DBP interactions indicated the lower percentage changes in SBP and DBP of the TS. In addition, the results showed a significant decrease of the CC in the TS but not in the CS throughout the ST + CPT combined stress tests. HR remained stable in TS between the initial rest period and the CPT unlike what happened in CS. Conclusion On the basis of blood pressure and cortisol changes, these results suggest an antistress profile of this S1–casein hydrolysate in human subjects.  相似文献   
136.
137.
138.
139.
Background Patients with prostate cancer with a pre-operative prostate-specific antigen (PSA) τ;15ng/ml who undergo radical retropubic prostatectomy (RRP) generally do not have a good outcome, yet may have organ-confined cancer and should be offered the option of surgery. Aim To assess the outcome of patients who underwent RRP with a pre-operative PSA ≥ 15ng/ml. Methods Thirty-four patients, mean pre-operative PSA: 25.46ng/ml (15.03–76.6) and mean Gleason score: 6.4 (5–9) were assessed. Results Two groups were identified. Group I: 41% (14/34) have no biochemical recurrence to mean follow up of 58 months (30–106). Mean PSA: 18.8ng/ml (15.03–25.84). Mean Gleason score: 6.1 (5–7). Clinical stage: T1c in 80%. No patient had seminal vesicle or lymph node involvement. Group II: 59% (20/34) have biochemical recurrence or died (3) from their disease to mean follow up of 66 months (36–98). Mean PSA: 28.9ng/ml (15.28–76.6). Mean Gleason score: 6.7 (5–9). Clinical stage: T1c in 25%. Eleven patients had seminal vesicle (8) involvement or positive lymph nodes (3) or both (2). Conclusion RRP seems feasible in patients whose pre-operative PSA is between 15 and 25ng/ml with stage T1c, Gleason score ≤ 7 and negative lymph node frozen section.  相似文献   
140.
Rationale. Modafinil is a wake-promoting agent that affects hypothalamic structures involved in the homeostatic and circadian regulation of vigilance. Administered during sleep deprivation, it reduces the need for prolonged recovery sleep and decreases the rebound in EEG slow-wave activity. These diachronic effects suggest an action of modafinil on a homeostatic sleep regulatory process. Objectives. The aim of this study was to determine whether modafinil, in comparison to the d-amphetamine reference psychostimulant and to placebo, interferes with the vigilance regulatory processes reflected in the EEG during waking. Methods. Thirty-three healthy subjects were investigated during 60 h of sustained wakefulness in a double-blind placebo-controlled parallel-design study. A 4-min maintenance-of-wakefulness test administered hourly allowed the concomitant assessment of alertness and waking EEG activity. The effects of equipotent psychostimulant dosages (modafinil 300 mg and d-amphetamine 20 mg) were evaluated at the beginning of the first sleep deprivation night, at the end of the second sleep deprivation night and in the afternoon preceding the first recovery night. Results. One hour following ingestion, both psychostimulants increased alertness during 10–12 h, independently of the time of administration. At the level of the waking EEG, d-amphetamine attenuated the natural circadian rhythm of the different frequency bands and suppressed the sleep deprivation-related increase in low frequency (0.5–7 Hz) powers. In contrast, modafinil, which exhibited a transient amphetamine-like effect, had slight effect on circadian rhythms. Its selective action was characterized by maintenance of the α1 (8.5–11.5 Hz) EEG power, which under placebo exhibited a homeostatic decrease paralleling that of alertness with a circadian trough at night. Conclusions. These findings demonstrate that the alertness-promoting effects of modafinil and d-amphetamine involve distinct EEG activities and do not reside on the same vigilance regulatory processes. While d-amphetamine inhibits the expression of a sleep-related process, probably through a direct cortical activation masking EEG circadian rhythms, modafinil, through a synchronic effect, preferentially disrupts the homeostatic down-regulation of a waking drive. Electronic Publication  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