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   1374篇
  免费   80篇
  国内免费   39篇
耳鼻咽喉   7篇
儿科学   48篇
妇产科学   9篇
基础医学   133篇
口腔科学   34篇
临床医学   169篇
内科学   410篇
皮肤病学   11篇
神经病学   93篇
特种医学   111篇
外国民族医学   1篇
外科学   171篇
综合类   19篇
预防医学   70篇
眼科学   35篇
药学   116篇
肿瘤学   56篇
  2023年   4篇
  2022年   6篇
  2021年   19篇
  2020年   16篇
  2019年   17篇
  2018年   29篇
  2017年   28篇
  2016年   24篇
  2015年   29篇
  2014年   34篇
  2013年   48篇
  2012年   50篇
  2011年   61篇
  2010年   40篇
  2009年   33篇
  2008年   55篇
  2007年   74篇
  2006年   79篇
  2005年   73篇
  2004年   63篇
  2003年   52篇
  2002年   46篇
  2001年   58篇
  2000年   54篇
  1999年   35篇
  1998年   33篇
  1997年   28篇
  1996年   29篇
  1995年   16篇
  1994年   21篇
  1993年   12篇
  1992年   30篇
  1991年   17篇
  1990年   24篇
  1989年   41篇
  1988年   27篇
  1987年   23篇
  1986年   18篇
  1985年   20篇
  1984年   11篇
  1983年   10篇
  1982年   9篇
  1981年   16篇
  1980年   8篇
  1979年   10篇
  1977年   6篇
  1975年   5篇
  1973年   5篇
  1971年   4篇
  1969年   6篇
排序方式: 共有1493条查询结果,搜索用时 15 毫秒
21.
Acute porphyria is rare in orientals. We describe a Chinese woman with recurrent generalised tonic-clonic seizures and abdominal pain. Genomic DNA studies identified a heterozygous base substitution from guanine to adenine at nucleotide position 503, resulting in substitution of arginine by histidine at position 168 of the protein (R168H). This genetic abnormality is similar to the mutation reported in Caucasians with variegate porphyria. To the best of our knowledge, this is the first report in the English literature a Chinese patient with variegate porphyria with an identifiable mutation. A brief review of porphyria is presented.  相似文献   
22.
Removal of the olfactory bulbs of male golden hamsters results in a marked increase in tonic gonadotropin, prolactin and testosterone secretion which counteracts inhibitory effects of manipulations such as maintenance on short photoperiod, food restriction or treatment with gonadal steroids. The bulbectomy-induced increase in hormone secretion is interpreted to reflect a tonic inhibitory influence of the olfactory bulbs. This inhibition is not dependent upon chemosensory stimulation and may be mediated by olfactory bulb fibers projecting through the lateral olfactory tract to or through the olfactory tubercle. This review will relate these studies conducted on hamsters to results in other species, such as the rat, where the olfactory bulbs enhance serum gonadotropin levels.  相似文献   
23.
24.
25.
Inflamed fibronectin: an altered fibronectin enhances neutrophil adhesion   总被引:4,自引:0,他引:4  
Vercellotti  GM; McCarthy  J; Furcht  LT; Jacob  HS; Moldow  CF 《Blood》1983,62(5):1063-1069
Recent investigations have emphasized the role of activated granulocytes in mediating vascular endothelial injury in the pathogenesis of shock lung. In vitro studies have indicated that tight adherence of the neutrophil to the endothelium is crucial for the development of cellular injury. Fibronectin is critical to cell-to- substratum and cell-to-cell interactions. Since fibronectin resides in plasma, on endothelial cell surfaces and is secreted into cell matrices, the adhesive properties of fibronectin must be modulated, lest universal cell agglomeration occur, yet be enhanced when cell attachment is appropriate. In these studies, treatment of fibronectin- coated surfaces with neutrophil release products increased the adhesion of activated neutrophils. Similarly, endothelial cells treated with neutrophil release products become a more adherent substrate for neutrophils. This enhanced adherence generated by treatment of fibronectin with neutrophil supernatants is inhibitable by heat and the lysosomal proteinase inhibitor, pepstatin-A. Neutrophil release products cause proteolytic fragmentation of fibronectin and enhanced fibronectin immunofluorescence on endothelial cells. In addition, neutrophils are more injurious to endothelial cells that have been pretreated with neutrophil release products. Neutrophils may enhance their own adherence to endothelial cells by altering fibronectin, and this altered, or "inflamed," fibronectin may serve as an amplifier of inflammation.  相似文献   
26.
The impact of occupational stressful life events on psychological distress and blood pressure was examined among employees of a major New York City brokerage firm undergoing massive layoffs. One hundred thirty-nine employees of the firm, who had participated in a blood pressure screening in 1986, were rescreened during the period of layoffs within their company in 1989. About two-thirds of the 139 employees reported being "somewhat" or "very" anxious or upset in 1989 during the period of layoffs, and psychological distress was significantly elevated among those employees reporting possible or definite layoff or job change and/or difficulty in obtaining a comparable job. However, we found no increase in overall blood pressure level, and no effect of anticipation of job loss on 1989 blood pressure when controlling for 1986 blood pressure level, age, body mass index, work hours, and other demographic variables. On the other hand, employment in a department sold to another employer on the day of screening, as well as employment in a clerical job title, were both associated with significant increases in diastolic blood pressure of about 5 mm Hg.  相似文献   
27.
In order to interest businesses in buying mental health services for their employees, professionals must be able to speak the businessman's language and market their product--mental health services. They must emphasize the cost-effectiveness of mental health care and explain how the business can benefit from including such services in the company's benefits package. The authors describe some concepts and strategies they found helpful when they ventured into the business community to "sell" the services of their community mental health center. They discuss such factors as the need to present a polished, professional image and to gear services to the needs of the particular employer and his employees.  相似文献   
28.
The variation in colorectal cancer (CRC) incidence worldwide strongly suggests a role for dietary influences. Based on epidemiological data, protective effects of vegetables and fruit intake on CRC are widely claimed, while other data indicate a possible increased CRC risk from (higher) dietary fat intake. Therefore, we have investigated single and interactive effects of dietary fat and a vegetable-fruit mixture (VFM) in the ApcMin mouse, a mouse model for multiple intestinal neoplasia. In this study, four different diets (A-D) were compared, which were either low in fat (20% energy diets A/B) or high in fat (40% energy diets C/D). In addition, 19.5% (wt/wt) of the carbohydrates in diets B and D were replaced by a freeze-dried VFM. The diets were balanced so that they only differed among each other in fat/carbohydrate content and the presence of specific plant-constituents. Because the initiation of intestinal tumors in ApcMin mice occurs relatively early in life, exposure to the diets was started in utero. Without the addition of VFM, mice maintained at a high-fat diet did not develop significantly higher numbers of small or large intestinal adenomas than mice maintained at a low-fat diet. VFM added to a low-fat diet significantly lowered multiplicity of small intestinal polyps (from 16.2 to 10.2/mouse, 15 animals/group), but not of colon tumors in male ApcMin mice only. Strikingly, addition of VFM to female mice maintained on a low-fat diet and to both sexes maintained on a high-fat diet significantly enhanced intestinal polyp multiplicity (from 16.5 to 26.7 polyps/mouse). In conclusion, our results indicate that neither a lower fat intake nor consumption of VFM included in a high-fat diet decreases the development of polyps in mice genetically predisposed to intestinal tumor development.   相似文献   
29.
Safe and effective treatment of major depression, one of the most common comorbid conditions in individuals infected with HIV, significantly lowers morbidity and mortality from HIV disease. However, optimal treatment of both conditions is complicated by interactions between the disease processes as well as the pharmacological agents used to treat them. In patients with HIV it may be difficult to distinguish major depression from other physiological and emotional states that present with similar symptoms. Accurate diagnosis of major depression is thus complex and essential to preventing inappropriate exposure of patients to potentially harmful psychotropic medications. This review outlines important initial steps in making this diagnosis. All patients with HIV should be screened for depression by their medical providers and referred to a psychiatrist for full evaluation when necessary. The mainstay of treatment for major depression in patients with HIV disease is pharmacotherapy. Depressed patients with HIV respond to the same wide variety of antidepressant-class medications as depressed patients without HIV, including tricyclic antidepressants, paroxetine, fluoxetine and trazodone. Notably, new studies have also shown that some psychiatric medications can inhibit HIV replication. No particular antidepressant medication is superior for the treatment of depressed HIV-infected patients; however, the most important component of treatment of major depression in HIV-disease is patient adherence, which is highly influenced by antidepressant adverse effects. This review outlines adverse effects of antidepressant-class medications that are of particular concern in HIV-infected patients and describes pharmacological strategies for overcoming these potential barriers to medication adherence. This review also describes situations in which some adverse effects of antidepressant-class medications may be safely exploited to benefit depressed patients with HIV disease. Potential interactions between antidepressant-class medications and HIV medications, as well as pharmacological treatment strategies for treating the psychiatric adverse effects of HIV medications, are also discussed.  相似文献   
30.
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