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   8302篇
  免费   212篇
  国内免费   40篇
耳鼻咽喉   199篇
儿科学   731篇
妇产科学   369篇
基础医学   739篇
口腔科学   221篇
临床医学   670篇
内科学   1627篇
皮肤病学   398篇
神经病学   313篇
特种医学   207篇
外科学   1242篇
综合类   310篇
一般理论   2篇
预防医学   721篇
眼科学   167篇
药学   420篇
  1篇
中国医学   13篇
肿瘤学   204篇
  2017年   45篇
  2016年   33篇
  2015年   62篇
  2014年   63篇
  2013年   106篇
  2012年   117篇
  2011年   130篇
  2010年   119篇
  2009年   155篇
  2008年   86篇
  2007年   87篇
  2006年   112篇
  2005年   66篇
  2002年   37篇
  2001年   48篇
  1999年   69篇
  1998年   151篇
  1997年   185篇
  1996年   204篇
  1995年   160篇
  1994年   161篇
  1993年   156篇
  1992年   93篇
  1991年   100篇
  1990年   97篇
  1989年   110篇
  1988年   87篇
  1987年   98篇
  1986年   79篇
  1985年   58篇
  1984年   61篇
  1983年   51篇
  1982年   49篇
  1981年   57篇
  1980年   42篇
  1979年   31篇
  1978年   28篇
  1977年   43篇
  1976年   37篇
  1975年   26篇
  1959年   343篇
  1958年   759篇
  1957年   868篇
  1956年   771篇
  1955年   803篇
  1954年   780篇
  1953年   40篇
  1952年   35篇
  1949年   182篇
  1948年   125篇
排序方式: 共有8554条查询结果,搜索用时 15 毫秒
61.
A multi-institutional, prospective clinical study was undertaken to investigate whether the use of a heat and moisture exchanger (HME) in the period following total laryngectomy could prevent the development or reduce the severity of respiratory symptoms. Fifty-nine patients from three hospitals were provided with HMEs, either immediately post-surgery or, in the case of post-surgical radiotherapy, upon completion of the radiotherapy. For the total sample (n= 59) statistically significant improvements over time (between 3 and 6 months) could be found in forced expectoration (P < 0.05), in the perceived voice quality (P < 0.001), social anxiety (P < 0.001), social interactions (P < 0.001) and in feelings of anxiety and depression (P < 0.05). Repeated measures analysis of variance indicated statistically significant group differences over time in forced expectoration and stoma cleaning (P < 0.05). No statistically significant differences over time were noted between the regular and non(regular) HME user groups in voice quality or in various aspects of daily living.  相似文献   
62.
summary Controversy exists on the aetiological importance and the effect of jaw macrotrauma (fractures excluded) on the occurrence of temporomandibular joint disorders (TMD). The purpose of this study was to assess the incidence of jaw injury in TMD patients and to compare the severity of the symptoms, the clinical characteristics and the treatment outcome in TMD patients with or without a history of trauma to the head and neck region directly linked to the onset of symptoms. The study sample included 400 consecutive TMD clinical patients. In 24.5% of patients the onset of the pain and dysfunction could be linked directly to the trauma, mainly whiplash accidents. No significant differences could be found between the two groups in daily recurrent headache, dizziness, neck pain, joint crepitation and pain in the joints. Maximal mouth opening was less than 20 mm in 14.3% of patients with a history of trauma and in 4.1% of those without such a history. According to the Helkimo dysfunction index (DI), more trauma than non-trauma TMD patients belonged to the severe dysfunction groups (DI 4 and 5) at first examination. The outcome of a conservative treatment procedure (counselling, occlusal splint, physiotherapy, occasionally occlusal therapy and non-steroidal anti-inflammation drugs was not different between the two groups at the 1 year evaluation. The degree of maximal opening was similar: less than 20 mm in 3.7% and 2.2% in trauma and non-trauma patients respectively. Forty percent and 41% respectively were symptom free or had DI = 1. The results suggest that external trauma to the joint or to the jaw in general is an important initiating factor in the aetiology of TMD but also that the prognosis is favourable.  相似文献   
63.
Thirty patients diagnosed with breast cancer were included in a prospective randomized study comparing the in vivo priming effect of bioequivalent doses of glycosylated (lenograstim) and nonglycosylated (filgrastim) rG-CSF administration. Analysis of the efficacy of equivalent biological doses of both rG-CSFs showed no significant differences either in the mobilization of the subpopulations of PBPC considered (CD34+, CD34+/38, CD34+/DR), the content of such CD34+ cell subsets in the leukapheresis product, or the cost of the mobilization and collection procedures between both recombinant molecules. These results suggest that priming with bioequivalent doses of the two commercially available forms of glycosylated or nonglycosylated rG-CSF has a similar in vivo effect on PBPC mobilization.  相似文献   
64.
65.
BACKGROUND: The percentage of diabetic patients who do not benefit from the protective effect of aspirin is larger than in other populations at cardiovascular risk. OBJECTIVE: We compared the ability of aspirin to suppress TxA2 and platelet activation in vivo, in type-2 diabetics vs. high-risk non-diabetic patients. METHODS: Urinary 11-dehydro-TXB2, plasma sCD40 L, and sP-selectin were measured, together with indices of low-grade inflammation, glycemic control, and lipid profile, in 82 patients with type-2 diabetes and 39 without diabetes, treated with low doses of aspirin. RESULTS: Urinary 11-dehydro-TxB2, plasma sCD40L and sP-selectin were significantly higher in diabetics than in controls: [38.9 (27.8-63.3) vs. 28.5 (22.5-43.9) ng mmol(-1) of creatinine, P = 0.02], [1.06 (0.42-3.06) vs. 0.35 (0.22-0.95) ng mL(-1); P = 0.0001], [37.0 (16.8-85.6) vs. 20.0 (11.2-35.6) ng mL(-1), P = 0.0001], respectively. The proportion of individuals with diabetes increased across quartiles of 11-dehydro-TxB2, sCD40L, and sP-selectin, with the highest quartiles of 11-dehydro-TxB2, sCD40L and sP-selectin, including 66%, 93.3%, and 93.3% of individuals with diabetes. Markers of platelet activation positively correlated with indices of glycemic control but not with markers of low-grade inflammation. CONCLUSIONS: Platelet dysfunction associated with insufficient glycemic control, may mediate persistent platelet activation under aspirin treatment.  相似文献   
66.
Adoption studies have led to the suggestion that there may be two distinct subgroups of alcoholics with differing genetic contributions. Among 249 male alcoholics we used discriminant analysis to relate the features of type 1 and type 2 alcoholism it the presence or absence of a family history of alcoholism in male paternal relatives. We found that guilt and hinging, features usually attributed to type 1 (milieu-limited) alcoholism, were in fact more prevalent m the family history positive group. An additional cohort analysis found cohort-related variations in type 1/type 2 characteristics. The possible implications of these findings are discussed.  相似文献   
67.
68.
Policosanol is a new cholesterol-lowering drug isolated and purified from sugar-cane wax. which prevents the development of lipofundin-induced lesions and foam-cell formation in New Zealand rabbits and Wistar rats. This study was conducted to examine the effects of policosanol on foam-cell formation in carrageenan-induced granulomas in rats. Eighteen Wistar rats were randomly distributed in three experimental groups which received orally for 20 days Tween 20 H2O as vehicle (control group) or policosanol at 2.5 or 25 mg kg?1. At the 11th day. lipofundin was injected intrapcritoneally for 8 days to induce formation of foam cells in the granuloma. At day 13, carrageenan was injected subcutaneously for granuloma induction and seven days later animals were killed. A significant reduction of the foam-cell formation in granulomas of policosanol-treated rats was observed. It is concluded that policosanol prevents the development of foam cells in carrageenan-induced granulomas (extravascular medium) in rats.  相似文献   
69.
70.
A study aimed at investigating the behavioural effects of aztreonam and gentamicin, given separately or in combination, was carried out in mice. Animals were randomly assigned to two test conditions: acute and chronic treatment. Those receiving acute treatment had a single IP injection 60 min before the test. Those receiving chronic treatment had IP injections once daily for 5 successive days prior to the test. Behavioural patterns (ambulation, rearing, grooming and defecation) were assessed using the "open-field" test. The results indicate that, both after single and multiple dosing, aztreonam (10, 40 and 80 mg/kg IP) and/or gentamicin (10 mg/kg IP) do produce changes in the behaviour of animals. A rate increasing effect for certain behaviours (rearing, grooming and defecation) and a reduction in other behaviours (ambulation) seems to occur.  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