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   1568篇
  免费   111篇
耳鼻咽喉   19篇
儿科学   177篇
妇产科学   71篇
基础医学   199篇
口腔科学   117篇
临床医学   126篇
内科学   226篇
皮肤病学   69篇
神经病学   184篇
特种医学   43篇
外科学   119篇
综合类   18篇
预防医学   94篇
眼科学   76篇
药学   75篇
肿瘤学   66篇
  2021年   18篇
  2020年   25篇
  2019年   19篇
  2018年   35篇
  2017年   19篇
  2016年   19篇
  2015年   29篇
  2014年   33篇
  2013年   49篇
  2012年   69篇
  2011年   52篇
  2010年   36篇
  2009年   36篇
  2008年   44篇
  2007年   63篇
  2006年   61篇
  2005年   65篇
  2004年   80篇
  2003年   51篇
  2002年   57篇
  2001年   66篇
  2000年   67篇
  1999年   58篇
  1998年   23篇
  1997年   14篇
  1996年   18篇
  1995年   12篇
  1994年   15篇
  1993年   14篇
  1992年   31篇
  1991年   25篇
  1990年   26篇
  1989年   38篇
  1988年   39篇
  1987年   26篇
  1986年   28篇
  1985年   36篇
  1984年   31篇
  1983年   19篇
  1981年   13篇
  1980年   11篇
  1979年   18篇
  1978年   12篇
  1977年   13篇
  1976年   13篇
  1975年   15篇
  1974年   14篇
  1973年   20篇
  1972年   12篇
  1971年   13篇
排序方式: 共有1679条查询结果,搜索用时 435 毫秒
101.
102.
103.
The findings reported in this paper were based on a representative, city wide sample (N= 708) of Calgary youths (aged 15–24). Twenty six per cent of the respondents reported having used marijuana “in the past six months”. Contrary to Smart's (1970) differential school drop out hypothesis, no decline in drug use was reported by 17 and 18 year old students, As measured by Rotter's concept, internally oriented respondents were less apt than externals to use marijuana. As predicted, this correlation was stronger among high school than college respondents. Several other demographic correlates of marijuana use were found.  相似文献   
104.
The purpose of this investigation was to develop an in vitro technique for measurement of elastic properties of isolated vocal fold tissue. Larynges were excised from anesthetized dogs, immediately submerged in a Krebs-Ringer solution, and aerated with 95% oxygen and 5% carbon dioxide. The tissue was maintained in the aerated electrolyte solution throughout the experiment. The vocalis muscle was carefully dissected, with attachments to the arytenoid and thyroid cartilages maintained. The preparation was then subjected to isometric (constant length) force-elongation measures, which were converted to stress-strain values. Stage I of the investigation identified the dog model with the least intrastudy variability relative to the age, sex, and breed of the research animal, as well as to the effects of curare. Stage II investigated the effects of different instrumentation, definitions of reference length, methods of elongation, and effects of electrical stimulation. Once the procedure had been refined, the effects of age and sex were retested. There was a significant interaction between sex and strain and between age and strain. The least variability was obtained with curarized tissue from one sex of young, mixed-breed dogs, where an arbitrary 1 gram of initial force was the criterion for establishing "zero" strain. Problems associated with determination of reference length and various approaches to this problem are discussed.  相似文献   
105.
Mental health professionals working in community agencies give much of themselves in aiding clients to live more productive and satisfying lives. Consideration should now be given to assist these mental health professionals in meeting their own job-related needs. Industrial and organizational job satisfaction literature is reviewed to aid mental health agencies in their efforts to express and act on a greater concern for the job satisfaction (work morale) of agency staff. It is encouraged that ways of maintaining or increasing job satisfaction be investigated.  相似文献   
106.
In the identification of discrete and conglomerate retroperitoneal lymph node masses, MRI and CT performed equally well. No specific MRI characteristics were identified.  相似文献   
107.
The clinical, microbiologic, and immunologic parameters in HIV-infected subjects first presenting with disseminated Mycobacterium avium complex (DMAC) were determined. Four HIV-positive groups not yet on DMAC treatment were enrolled: 19 subjects with CD4 lymphocyte counts < or =50/microl thought to have DMAC on clinical grounds; 18 subjects newly found to have a positive blood culture for MAC; 25 asymptomatic controls (CD4 cell counts < or =50); and 25 asymptomatic controls (CD4 counts 100-250/microl). Outcome measures include comparisons between groups for clinical characteristics; results of cultures from blood, marrow, and gastrointestinal and respiratory tracts; immunological markers from staining of marrow and flow cytometry of circulating lymphocytes; and cytokine production of PBMCs. Only 21% of the 19 patients entered on suspicion of having DMAC grew MAC from blood or marrow. Neither clinical presentation nor laboratory tests differentiated those culture-positive from those culture-negative patients. However, prior PCP or multiple other opportunistic infections were more common in the DMAC group. MAC was isolated from 82% of marrow and 50% of blood specimens from the DMAC group. Respiratory or gastrointestinal colonization was present in 36% of DMAC subjects, but only 5% of non-DMAC subjects with CD4 counts <50 cells/microl. CD8+ cells were more frequent in bone marrow, and CD4 cells recognizing MAC antigen were more frequent in blood from DMAC subjects vs. controls. Results suggest an early stage of tissue dissemination preceding persistent bacteremia, and mucosal entry without persistence of colonization. MAC-specific T cell responses apparently develop and persist during DMAC, but are dysfunctional or too infrequent to prevent persistence.  相似文献   
108.
Residents of Massachusetts are positioned at almost the highest/most favorable end of all state rankings based on an overall listing of health, social conditions, and services. However, while these statistics are encouraging, they are not uniform throughout all population groups in the state. The challenge is to move beyond complacency with current standings to reach those in need.  相似文献   
109.
The mechanism of neuroprotection associated with systemically administered magnesium remains unclear. This investigation examined the acute effects of systemically administered MgSO4 on brain extracellular ([Mg]ecf) and intracellular ([Mg]i) fluid Mg concentrations, specific brain phosphorylated metabolites, and brain intracellular pH. Miniswine were studied with P-31 magnetic resonance spectra, to derive [Mg]i, and brain microdialysis probes, to measure [Mg]ecf. Animals were infused with MgSO4 (n = 5, 275 mg/kg over 30 min followed by 100 mg/kg over 30 min, designated MgHI) or Na2SO4 (n = 5, designated NaHI), and both groups underwent hypoxia-ischemia (HI) over the last 15 min of the infusions. Groups differed in plasma [Mg] at the completion of HI (9.1 +/- 1.5 versus 1.1 +/- 0.6 mM for MgHI and NaHI, respectively, p < 0.05). MgHI had elevations of [Mg]ecf (0.23 +/- 0.11 and 0.40 +/- 0.14 mM at control and completion of HI, respectively), and [Mg]ecf was unchanged for NaHI (p < 0.05 versus MgHI). At the completion of HI, MgHI had greater decreases in nucleoside triphosphate (NTP) (48 +/- 6% of control), and more brain acidosis after HI (6.01 +/- 0.07) compared with NaHI (NTP, 70 +/- 3% of control; brain pH, 6.51 +/- 0.14, both p < 0.05 versus MgHI). [Mg]i increased to elevated values during HI in both MgHI and NaHI (p < 0.05 versus control of each group) and remained higher in MgHI over the next 25 min (p < 0.05 versus NaHI). There were inverse correlations during HI between [Mg]i and brain NTP (r2 = 0.73 and 0.59 for MgHI and NaHI, respectively), and brain acidosis (r2 = 0.85 and 0.85 for MgHI and NaHI, respectively) in each group. These findings indicate complex effects of Mg on the brain. Elevation of [Mg]ecf may be beneficial with regards to excitatory neurotransmitters. However, greater disturbance of brain NTP concentration, more acidosis, and the increase in [Mg]i may offset any benefit. The results warrant further investigation using indicators of neuronal injury to determine whether Mg supplementation provides neuroprotection.  相似文献   
110.
Premenarchal recurrent periclitoral abscess: a case report   总被引:2,自引:0,他引:2  
BACKGROUND: Periclitoral abscesses in premenarchal girls is a serious condition and can have negative implications for future reproductive health. Recurrent periclitoral abscess in premenarchal girls is rare. CASE: An 11-year-old, premenarchal girl presented complaining of dysuria, vulvar swelling, pain and erythema of the clitoral hood and a similar episode 12 months previously. Intravenous antibiotics and local measures resulted in spontaneous drainage of the abscess. On day 3 the area was healing, and the patient was discharged on oral antibiotics and sitz baths. At her 6-month follow-up, she had a normal clitoral hood without tenderness or erythema. CONCLUSION: Broad-spectrum antibiotics and local measures may prevent surgical treatment and potential associated reproductive morbidity.  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