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   9486篇
  免费   730篇
  国内免费   14篇
耳鼻咽喉   158篇
儿科学   372篇
妇产科学   374篇
基础医学   1331篇
口腔科学   458篇
临床医学   957篇
内科学   1539篇
皮肤病学   274篇
神经病学   870篇
特种医学   350篇
外科学   1439篇
综合类   144篇
一般理论   3篇
预防医学   754篇
眼科学   214篇
药学   527篇
中国医学   13篇
肿瘤学   453篇
  2021年   146篇
  2019年   137篇
  2018年   151篇
  2017年   107篇
  2016年   138篇
  2015年   140篇
  2014年   207篇
  2013年   270篇
  2012年   365篇
  2011年   428篇
  2010年   230篇
  2009年   238篇
  2008年   350篇
  2007年   409篇
  2006年   434篇
  2005年   373篇
  2004年   358篇
  2003年   283篇
  2002年   291篇
  2001年   310篇
  2000年   285篇
  1999年   259篇
  1998年   104篇
  1997年   104篇
  1996年   89篇
  1995年   100篇
  1994年   97篇
  1993年   87篇
  1992年   210篇
  1991年   176篇
  1990年   218篇
  1989年   212篇
  1988年   211篇
  1987年   195篇
  1986年   186篇
  1985年   170篇
  1984年   140篇
  1983年   119篇
  1982年   77篇
  1981年   77篇
  1979年   119篇
  1978年   93篇
  1977年   83篇
  1975年   89篇
  1974年   91篇
  1973年   89篇
  1972年   78篇
  1971年   85篇
  1970年   83篇
  1969年   77篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
We report on our experience in the use of a new system of a totally implantable device for repeated vascular access in children, developed in 1989 by Pharmacia and named P.A.S. Port (Peripheral Access System Port). The P.A.S. Port is far smaller than other systems and has been designed for peripheral location in the arm. This avoids unsightly pectoral scars particularly in girls and allows insertion under local anesthesia. It is an interesting alternative to the Port-a-Cath for children older than 5 years of age. It is easily accepted by the patient as well as by the caring team.  相似文献   
32.
We report a case of a fatal toxic encephalomyelopathy in a 12-year-old girl due to prophylactic intrathecal injection of methotrexate and cytosine arabinoside, with a characteristic progressive symptomatology leading to death after 28 days. The location and type of neuropathological changes support the hypothesis of a direct toxic effect of methotrexate and/or cytosine arabinoside on structures directly exposed to the cerebrospinal fluid.  相似文献   
33.
The aim of this study was to investigate markers of serotonin and immune function in suicidal patients. Cytotoxic activity of natural killer cells (NK) and CD16 lymphocytes were studied in 28 suicide attempters and 26 healthy controls, and related in patients to 5-hydroxyindoleacetic acid (5-HIAA) in cerebrospinal fluid (CSF). Patients with CSF 5-HIAA below the median had significantly lower NK cell activity than other patients. CD16 cell frequency was significantly lower in patients than in controls, and patients also tended to have lower NK cell cytotoxicity than healthy controls. There were no statistically significant correlations between 4-hydroxy-3methoxyphenyl glycol (HMPG), homovanillic acid (HVA), CSF cortisol and NK cell activity. The results support the hypothesis of compromised immune function in suicidal patients with evidence of disordered serotonin function.  相似文献   
34.
Urine samples from 402 victims of ski accidents were analyzed for the presence of benzodiazepines (BZD) and alcohol. Eighty-one (20%) samples were positive for alcohol; BZD were detected in 34 (8.5%) cases. Ten of the samples (2.5%) were found to be positive for both alcohol and BZD. Subjects who were positive for either alcohol or BZD or both were older than the other persons examined. The prevalence of alcohol was significantly higher among male accident victims. BZD intake could be demonstrated to have a significant influence on the severity of injuries. Besides an increased awareness of the need for skier education regarding drug use, heightened attention of medical caregivers is warranted to inform their patients about potential accident hazards in sport activities when BZD are prescribed.  相似文献   
35.
In this longitudinal study of a random sample of North Carolinians over the age of 65 and living in their homes, 325 blacks and 280 whites were examined and interviewed 18 months after baseline examinations. Coronal caries incidence was greater among whites than blacks. The increment due to teeth becoming root fragments were similar for both races; however, there were more newly crowned teeth among whites. Newly crowned surfaces were not used as part of the caries increment in logistic regression models to investigate potential risk predictors. For blacks, caries development over the 18-month period was associated with a higher lactobacillus score and more coronal caries at baseline, more previously filled coronal surfaces, and lack of active membership in clubs or other groups. For whites, having no self-reported tooth sensitivity, having a lower socioeconomic index score, taking antihistamine medications at baseline, and having the perception of more problems after the age of 40 than before were all associated with the development of coronal caries.  相似文献   
36.
We describe a 39-year-old man in whom progressive pulsatile proptosis developed 2 days after he suffered a head injury. Computed tomography revealed an isolated blow-in fracture of the orbital roof with herniation of the left frontal lobe into the orbit. Neurosurgical intervention to repair the orbital defect led to full recovery.  相似文献   
37.
Idiopathic perioptic neuritis is a term used to describe noninfectious inflammatory disorders of the optic nerve sheaths, the causes of which are unknown. In the following report, a 68-year-old woman with bilateral visual loss was found to have chronic inflammation with necrobiotic granulomas of her optic nerve sheaths. The patient, who had no systemic condition known to be associated with necrobiotic granuloma, lost vision from infarction of the optic nerve parenchyma and from compression due to thickened meninges. Although there are similarities between the inflammatory reaction in this case to the necrobiotic dermatoses, the pathogenesis of this condition remains obscure.  相似文献   
38.
PURPOSE: This study was designed to identify risk indicators for the prevalence at enrollment and incidence over 36 months of periodontal pathology and coronal caries experience affecting third molars in a community-based study of people over 65 years of age. SUBJECTS AND METHODS: Data from a subsample of 810 dentate subjects from the Piedmont 65+ Study were available for analyses. All visible teeth were examined. Periodontal probing measures were taken at 2 sites, mesiobuccal and buccal/facial. Clinical data on caries experience were collected by visual-tactile examination. At enrollment, 340 subjects had at least 1 visible third molar; all were examined for caries experience. Periodontal probing measures were available for 277 of these same subjects. The significance of the possible risk indicators for periodontal pathology and caries affecting third molars was determined by chi(2) tests. Statistical significance was set at .05. Logistic multivariable models were used to derive odds ratios and 95% confidence intervals. RESULTS: African-American subjects were more likely to have visible third molars (P < .01). Caucasian subjects were more likely to have third molar coronal caries experience (P < .01), as were subjects with greater than a high school education and those with a dental visit within 3 years (both P < .01). However, African American subjects were more likely to have periodontal pathology, CALs >/= 3 mm on third molars (P < .01), as were those who used tobacco (P < .01). None of the other risk indicators we studied were associated with progression of periodontal pathology or coronal caries experience on visible third molars. CONCLUSION: In this population study of senior adults, Caucasians and African Americans appear to have different levels of risk for caries experience and periodontal pathology affecting retained third molars.  相似文献   
39.
40.
S Brett  J M Orrell  J Swanson Beck    J Ivanyi 《Immunology》1992,76(1):129-132
Mice infected by intraperitoneal injection of Mycobacterium tuberculosis were studied over a 23-week period. They showed progressive infection in the lung (with increasing microbial count and granuloma size) whereas viable bacillary counts remained largely stationary in the spleen and in the liver. The influence of H-2 genes on the progression of the lung infection was studied in four congenic strains of animals with B10 and three congenic strains of animals with BALB backgrounds. H-2k mice had significantly higher bacterial counts in the lung than H-2b mice on both B10 and BALB backgrounds, BALB. K (H-2k) mice were also more susceptible than BALB/c (H-2d) mice. Results with recombinant strains showed that bacillary counts and granulomatous infiltration were lower in the B10 (KbAbE-Db) compared with B10.A(3R) (KbAbEbDd) strain and in B10.A(4R) (KkAkE-Db) compared with B10.BR (KkAkEkDk) mice. This resistance to the late expansion of tuberculous infection in the lungs may be associated with the lack of an expressed I-E molecular or with the expression of the Db molecule.  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