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   5179篇
  免费   365篇
  国内免费   7篇
耳鼻咽喉   64篇
儿科学   277篇
妇产科学   96篇
基础医学   669篇
口腔科学   175篇
临床医学   545篇
内科学   1162篇
皮肤病学   79篇
神经病学   468篇
特种医学   381篇
外科学   542篇
综合类   79篇
一般理论   10篇
预防医学   360篇
眼科学   91篇
药学   249篇
中国医学   1篇
肿瘤学   303篇
  2021年   38篇
  2019年   36篇
  2018年   57篇
  2017年   48篇
  2016年   65篇
  2015年   50篇
  2014年   107篇
  2013年   156篇
  2012年   195篇
  2011年   223篇
  2010年   117篇
  2009年   97篇
  2008年   172篇
  2007年   222篇
  2006年   236篇
  2005年   195篇
  2004年   217篇
  2003年   208篇
  2002年   186篇
  2001年   164篇
  2000年   201篇
  1999年   142篇
  1998年   55篇
  1997年   43篇
  1996年   37篇
  1995年   74篇
  1994年   46篇
  1993年   47篇
  1992年   162篇
  1991年   151篇
  1990年   160篇
  1989年   153篇
  1988年   133篇
  1987年   119篇
  1986年   127篇
  1985年   121篇
  1984年   95篇
  1983年   84篇
  1982年   47篇
  1981年   39篇
  1980年   37篇
  1979年   78篇
  1978年   53篇
  1976年   45篇
  1975年   39篇
  1974年   43篇
  1973年   56篇
  1972年   51篇
  1971年   41篇
  1970年   40篇
排序方式: 共有5551条查询结果,搜索用时 31 毫秒
1.
2.
Two examples of localized primary amyloid tumor of the breast are presented, including one patient with metachronous bilateral lesions. Our findings and review of the literature indicate that this rare lesion occurs predominantly in elderly females and can be mammographically and clinically confused with carcinoma. Fine-needle aspiration biopsy can be a useful procedure to make a preliminary diagnosis. Congo red staining with prior potassium permanganate incubation confirmed the AL type of amyloid in our two cases; this might be the predominant type in the localized form involving the breast. Immunofluorescence studies demonstrated IgA, with kappa and lambda light-chain deposition within the amyloid foci in one case, and intracytoplasmic IgG with both light chains within plasma cells and amyloid deposits of the second case. Ultrastructural examination of one of the cases showed characteristic findings of straight, nonbranching fibrils of 4-9 nm, diagnostic of amyloid. From our findings and a review of the literature, we conclude that amyloid tumors of the breast can occur in three separate settings: secondary amyloidosis, systemic or multiple myeloma associated amyloidosis, and as a localized primary type having a benign course.  相似文献   
3.
We evaluated the diagnostic performance of 15 clinical case definitions for pertussis in 233 patients who developed acute respiratory illness during community outbreaks in Wisconsin and Delaware. Using results from culture (Regan-Lowe media) and serology (Ig-class-specific ELISA) as diagnostic standards, cough for greater than or equal to 14 days was both sensitive (84 per cent-92 per cent) and specific (63 percent-90 per cent) in identifying patients with pertussis. This definition may be useful in monitoring pertussis outbreaks and for investigating contacts of culture-positive cases.  相似文献   
4.
Systemic disease may present first in the foot. The authors present a case in which the marrow of resected bone tissue from a phalanx showed the changes of chronic lymphocytic leukemia (CLL). Subsequent blood examination confirmed this diagnosis.  相似文献   
5.
6.
Immunosuppressed persons are at greater risk of developing malignancies. In human immunodeficiency virus (HIV) immunosuppression the most common oral cancers are Kaposi's sarcoma and non-Hodgkin's lymphoma. Squamous cell carcinoma has also been reported to be associated with HIV disease. Kaposi's sarcoma is the most frequent neoplastic disease in acquired immunodeficiency syndrome and is by far the most common in the head and neck area. This article reviews the prevalence, clinical features, and management of these diseases in HIV infection.  相似文献   
7.
Among adults with intellectual disability, virtually everyone with Down's syndrome (DS) over the age of 40 years has neuropathology currently viewed to be consistent with a diagnosis of Alzheimer disease (AD), while other adults with intellectual disability without DS display an increased prevalence of Alzheimer-type neuropathology after they reach the age of 65. This paper presents the results of discussions by an epidemiology workgroup, formed at an international conference convened to discuss AD among people with intellectual disability, concerning: (I) the incidence and prevalence of clinical dementia in adults with intellectual disability; (2) risk factors for the development of AD in adults with intellectual disability; and (3) a minimum data set that would be of great utility for future research on AD in adults with intellectual disability.  相似文献   
8.
We have identified a secreted glycoprotein with an apparent molecular weight of 39,000 that is inhibited by estrogens and stimulated by antiestrogens in the MCF-7 human breast cancer cell line. The protein was detected within 24 h of hormone treatment with inhibition occurring at concentrations as low as 10(-11) M estradiol and stimulation occurring with antiestrogens. When phenol red, which has been found to have estrogenic activity, is removed from the tissue culture medium, no inhibition of cell growth or induction of the Mr 39,000 protein is seen with antiestrogens. A 6-fold decrease in the amount secreted in the presence of estrogens is seen under these conditions. The induction was specific in that growth inhibition by several other means did not induce expression of the Mr 39,000 protein. The Mr 39,000 protein has been identified as a glycoprotein complex that can be resolved into four polypeptides with two major components that migrate in the pH range of 5.5 to 6.3 by two-dimensional gel electrophoresis. This protein is the first evidence that estrogens inhibit a specific protein and it may prove useful as a marker of antiestrogen-induced growth arrest in breast cancer.  相似文献   
9.
Rats with unilateral 6-hydroxydopamine lesions of substantia nigra rotate (circle) when placed, undrugged, in the environment in which they have previously been treated with apomorphine. This conditioned rotation, like the unconditioned rotation which acutely follows the administration of apomorphine, is directed away from the side with the lesion, i.e., the rotation is contralateral. Here, rats that had been administered apomorphine weeks earlier were tested, in a crossover design, for the expression of conditioned rotation following treatment with saline and with alpha-methyltyrosine. When administered four hours prior to testing, 100 mg/kg alpha-methyltyrosine significantly antagonized the expression of classically conditioned rotation. In a second group of animals, alpha-methyltyrosine had no effect on the unconditioned rotation induced by 0.05 mg/kg apomorphine.  相似文献   
10.
BACKGROUND: The effects on morbidity were examined of providing an educational intervention and a written guided self-management plan to the parents of pre-school children following a recent attendance at hospital for asthma or wheeze. METHODS: A prospective, randomised, partially blinded, controlled trial was designed at two secondary care centres. Over a 13 month period 200 children aged 18 months to 5 years at the time of admission to a children's ward or attendance at an accident and emergency department or children's (emergency) assessment unit (A&E/CAU) with a primary diagnosis of acute severe asthma or wheezing were recruited. 101 children were randomised into the control group and received usual care and 99 were assigned to the intervention group and received: (1) a pre-school asthma booklet; (2) a written guided self-management plan; and (3) two 20 minute structured educational sessions between a specialist respiratory nurse and the parent(s) and child. Subjects were assessed at 3, 6, and 12 months. The main outcomes were GP consultation rates, hospital re-admissions, and attendances at A&E/CAU. Secondary outcomes included disability score, caregivers' quality of life, and parental knowledge of asthma. RESULTS: There were no statistically significant differences between the two groups during the 12 month follow up period for any of the main or secondary outcome measures. CONCLUSIONS: These results do not support the hypothesis that the introduction of an educational package and a written guided self-management plan to the parents of pre-school children with asthma who had recently attended hospital for troublesome asthma or wheeze reduces morbidity over the subsequent 12 months.  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