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   3495篇
  免费   208篇
  国内免费   30篇
耳鼻咽喉   3篇
儿科学   147篇
妇产科学   39篇
基础医学   631篇
口腔科学   98篇
临床医学   370篇
内科学   713篇
皮肤病学   119篇
神经病学   271篇
特种医学   302篇
外国民族医学   2篇
外科学   366篇
综合类   78篇
一般理论   9篇
预防医学   172篇
眼科学   53篇
药学   211篇
中国医学   2篇
肿瘤学   147篇
  2018年   41篇
  2017年   35篇
  2016年   45篇
  2015年   48篇
  2014年   40篇
  2013年   113篇
  2012年   98篇
  2011年   73篇
  2010年   73篇
  2009年   70篇
  2008年   79篇
  2007年   93篇
  2006年   102篇
  2005年   83篇
  2004年   73篇
  2003年   78篇
  2002年   71篇
  2001年   73篇
  2000年   74篇
  1999年   84篇
  1998年   102篇
  1997年   109篇
  1996年   121篇
  1995年   83篇
  1994年   89篇
  1993年   85篇
  1992年   64篇
  1991年   71篇
  1990年   75篇
  1989年   99篇
  1988年   85篇
  1987年   72篇
  1986年   81篇
  1985年   66篇
  1984年   71篇
  1983年   35篇
  1982年   43篇
  1981年   52篇
  1980年   58篇
  1978年   39篇
  1977年   44篇
  1976年   52篇
  1975年   41篇
  1972年   36篇
  1965年   53篇
  1964年   51篇
  1963年   47篇
  1962年   41篇
  1961年   40篇
  1960年   67篇
排序方式: 共有3733条查询结果,搜索用时 853 毫秒
21.
The effect of acute and sequential volaemic changes on the gastroduodenal flow of saline was assessed in 23 anaesthetized dogs following two different experimental protocols. Hypervolaemia, by i. v. infusion of saline, induced a gradual decrease on gastroduodenal flow which amounted to 76% below control values (P < 0.001) when volaemic expansion attained 5% of body weight. This effect was volume dependent (17% increase on gastroduodenal flow per volume of infused saline equivalent to 0.5% of body weight, P < 0.001), lasted for at least 90 minutes after infusion was completed and was also obtained by expanding previously bled animals. Hypovolaemia due to bleeding was followed by an increase on gastroduodenal flow of about 88% above control values (P < 0.05) when haemorrhage was equal to 3% of body weight. This effect was also volume dependent (23 % increase on gastroduodenal flow per volume of blood shed equivalent to a 0.5% of body weight, P < 0.01) and was reversed after blood volume was restored. These modifications in the resistance of the gastroduodenal segment to the flow of liquid due to acute volaemic changes suggest that the extracellular fluid volume modulates the contractile activity of the gastroduodenal portion of the gut possibly to set a gastroduodenal handling of liquid adequate to cope with volaemic imbalances.  相似文献   
22.
23.
24.
The neurotoxic effects of single subcutaneous injections of1000 mg triphenyl phosphite (TPP)/kg body weight were investigatedin White Leghorn hens. At 7 days postexposure, birds began toshow signs of mild to moderate ataxia that progressed to severeataxia and paralysis at 21 days. Inhibition of whole brain neuropathytarget esterase was 85% at 48 hr and 73% by 21 days postexposure.After postexposure periods of 7, 14, and 21 days, hens werekilled and their brains and spinal cords were examined for degeneratingaxons and terminals using the Fink-Heimer silver impregnationmethod. A small amount of degeneration was noted at 7 days.By 21 days, dense degeneration was noted in the spinal graymatter and funiculi. Degeneration was also present in the granularcell layer of cerebellar folia I-VI and in nuclei and fibertracts of the medulla. Moderate to dense degeneration was alsoseen in several forebrain and midbrain areas including the paleostriatum,ansa lenticularis, the dorsointermediate thalamic nucleus, lateralspiriform, pedunculopontine tegmental, and lateral mesencephalicnuclei and in the deeper layers of the optic tectum. These resultsindicate that, in addition to affecting the spinal cord andbrainstem, exposure to TPP also damages higher order centersresponsible for processing and integrating sensorimotor, visual,and auditory information.  相似文献   
25.
Homicide inflicts massive injury upon the intrapsychic and interpersonal realities of the surviving kin of murder victims. A New York City pilot program of outreach and counselling to 1182 families of Brooklyn homicide victims suggests that surviving kin undergo the symptoms of traumatic stress disorder. Recovery is prolonged by knowledge that the perpetrator is usually alive and in some cases unpunished, by repetitive confrontations with the criminal justice system and by the multiple losses endured: loss of a family member, loss of illusions of safety and invulnerability, loss of a sense of trust in the surrounding community, and loss of a belief system. Effective help to survivors requires interventions that respond to all aspects of the survivors' losses.  相似文献   
26.
27.
28.
BACKGROUND CONTEXT: Results of lumbar fusion surgery have been mixed and procedures are costly. Interbody cage lumbar fusion (ICLF) has been advanced to improve arthrodesis and clinical outcomes; however, little attention has been given to ICLF costs or potential predictors of these expenses. PURPOSE: To depict medical and compensation costs associated with ICLF in a Utah cohort of patients receiving workers' compensation as well as to investigate predictors of costs. STUDY DESIGN/SETTING: A retrospective-cohort research design was used involving completion of presurgical and postsurgical medical record reviews and accrual of medical and compensation costs. Presurgical variables included in a regression model were presurgical spinal pathophysiology rating, obesity, and litigation status. PATIENT SAMPLE: Forty-three consecutive patients who were compensated by the Workers' Compensation Fund of Utah and underwent ICLF. OUTCOME MEASURES: Total accrued compensation and medical costs. METHODS: A retrospective review of presurgical variables and total accrued compensation and medical costs was conducted. RESULTS: Multiple regression analysis indicated that nonpathophysiological factors predicted compensation costs (lawyer involvement [beta=0.40]; obesity [beta=0.34]). Specifically, compensation for those with versus without lawyers was $41,657 versus $24,837, and for those who were obese versus nonobese was $46,152 versus $28,168. Arthrodesis was correlated with medical costs (r=-0.47, p=.002), with incurred costs for patients achieving solid fusion versus pseudarthrosis equaling $38,881 versus $71,655, respectively. CONCLUSIONS: Considerable costs were associated with ICLF, particularly for those who were obese, involved in litigation, or failed to achieve solid fusion. With regard to compensation costs, the findings support the importance of assessing nonpathophysiological factors in spinal fusion patients.  相似文献   
29.
The general public of the City of Bergen, Norway was Invitedto participate in a cholesterol screening programme in October1988. Participants received the results of the cholesterol screeningand nutritional information from trained health personnel. Ashort questionnaire was mailed to all 354 participants 1–2weeks after the initial cholesterol screening. In March 1990,all participants were invited to have their cholesterol levelsre-examined. Psychosocial factors believed to be predictiveof future serum cholesterol changes were assessed at baselinealong with demographic variables. The majority of participants(61%) reduced their cholesterol level from October 1988 to March1990, and the average reduction in cholesterol level for thetotal population was 4.0%. Baseline cholesterol levels, beingconfident of one's own ability to change one's diet (self-efficacy),seeing heart disease risk reduction as very important, and maritalstatus were factors that significantly predicted successfulcholesterol reduction 18 months later.  相似文献   
30.
Postoperative radiation therapy in the management of lung cancer   总被引:1,自引:0,他引:1  
Postoperative radiation therapy for lung cancer is still controversial. In a 9-year period, 69 patients with non-oat-cell carcinoma of the lung (16% stage I, 26% stage II, and 58% stage III) received such therapy. The radiation dose was less than 5,000 cGy in 42 patients, 5,000-5,900 cGy in 16, and 6,000 cGy or more in 11; follow-up ranged from 24 to 64 months. Actuarial survival at 2 and 4 years was 50% and 16%, respectively, for squamous cell carcinoma, and 40% and 26% for adenocarcinoma. The 5-year survival for stages I, II, and III cancer was 29%, 17%, and 19%, respectively. Histologic findings and type of surgery did not affect survival, but the radiation dose apparently did. The 3-year survival for patients who received less than 6,000 cGy was 35%, compared with 73% for patients who received higher doses. In eight patients, treatment failed within the irradiated volume: all had received doses of less than 6,000 cGy, and the volume in three was judged to be inadequate.  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