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   63854篇
  免费   4741篇
  国内免费   1763篇
耳鼻咽喉   838篇
儿科学   1187篇
妇产科学   2214篇
基础医学   8050篇
口腔科学   1161篇
临床医学   6834篇
内科学   11944篇
皮肤病学   1190篇
神经病学   3958篇
特种医学   2613篇
外国民族医学   6篇
外科学   8530篇
综合类   4202篇
现状与发展   7篇
一般理论   11篇
预防医学   3501篇
眼科学   1400篇
药学   5333篇
  21篇
中国医学   1678篇
肿瘤学   5680篇
  2023年   525篇
  2022年   1321篇
  2021年   2155篇
  2020年   1308篇
  2019年   1620篇
  2018年   2000篇
  2017年   1517篇
  2016年   1567篇
  2015年   2331篇
  2014年   2916篇
  2013年   3392篇
  2012年   4816篇
  2011年   4689篇
  2010年   2989篇
  2009年   2614篇
  2008年   3539篇
  2007年   3539篇
  2006年   3383篇
  2005年   3124篇
  2004年   2827篇
  2003年   2705篇
  2002年   2349篇
  2001年   1843篇
  2000年   1609篇
  1999年   1336篇
  1998年   553篇
  1997年   457篇
  1996年   417篇
  1995年   377篇
  1994年   348篇
  1993年   242篇
  1992年   711篇
  1991年   582篇
  1990年   531篇
  1989年   484篇
  1988年   421篇
  1987年   424篇
  1986年   355篇
  1985年   295篇
  1984年   229篇
  1983年   191篇
  1982年   114篇
  1981年   122篇
  1980年   99篇
  1979年   205篇
  1978年   161篇
  1977年   103篇
  1976年   110篇
  1975年   102篇
  1974年   99篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Late-onset congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency is a cause of hirsutism in adult women. Its reported frequency of occurrence in hirsute women has varied from 0-30%, but the number of patients studied was small. To establish the incidence of CAH, 83 unselected hirsute women were studied prospectively with a standard ACTH stimulation test. On the basis of an exaggerated response of serum 17 alpha-hydroxyprogesterone to ACTH, 1 patient with CAH was found, for an incidence of 1.2%. The 95% confidence limits for the incidence of CAH among hirsute women were 0% and 3.4%. Five of seven hirsute women without CAH whose serum 17 alpha-hydroxyprogesterone levels rose above 3 ng/ml in response to ACTH had simultaneous serum progesterone values consistent with recent ovulation. Since routine screening of all hirsute women by means of ACTH stimulation does not appear to be cost effective, reported cases of CAH were reviewed in order to discern potentially helpful clinical clues. Severe hirsutism, virilization, early onset of symptoms, short stature, familial occurrence, and regular menses were identified as the clinical characteristics associated with late-onset CAH.  相似文献   
992.
To assess the diagnostic value of transesophageal two-dimensional echocardiography (TEE) as compared with transthoracic echocardiography (TTE), TTE and TEE were performed in eight consecutive patients (age range from 20 to 76 years, six male and two female) with clinical evidence of malignant tumors arising from the liver (n = 1), lung (n = 3), larynx (n = 1), osteogenic sarcoma (n = 1), lymphoma (n = 1), and yolk sac tumor in the anterior mediastinum (n = 1). In one case, the gastroscope could not be inserted because of tumor compression of the esophagus. Transesophageal echocardiography provided superior imaging in the detection of intracavitary metastatic lesions. In the case of right ventricular outflow tract tumor and greater vessel involvement, TTE may provide more imaging than TEE due to a blind area in this region by the transesophageal approach. In conclusion, TEE is complementary to TTE in the diagnosis of metastatic cardiac tumor.  相似文献   
993.
994.
OBJECTIVE: The aim of this study was to examine the effect of percutaneous oestradiol on the lipid profile and on atheroma formation using an animal model. METHODS: The study was of 12 weeks duration. Fifty sexually mature female New Zealand White rabbits were divided into five groups of equal size. Two groups acted as controls and received normal rabbit chow. Rabbits in one of these groups were ovariectomized. The remaining three groups were ovariectomized but received 1% cholesterol enriched rabbit chow. One of these cholesterol-fed groups received 0.3 mg/kg percutaneous oestradiol daily whilst another received 0.1 mg/kg oral oestradiol daily. Measurements of concentrations of total cholesterol (TC), high density lipoprotein cholesterol (HDL-C) and triglycerides (TG) were made at the beginning and end of the study. Aortic atheroma formation was measured using computerized image analysis of uptake of Sudan III staining. RESULTS: After 12 weeks there were significant increases in the mean concentrations of TC in the three cholesterol-fed groups compared with controls (P < 0.001). Changes in HDL-C and TG concentrations were less consistent. The mean area of aortic atheroma formation was significantly less in both the percutaneous oestradiol group (4.9%) and the oral oestradiol group (8.6%) compared with the non-oestrogen-treated cholesterol-fed group (19.5%) (P < 0.001, < 0.01 respectively). CONCLUSION: These results suggest that percutaneous oestradiol has a direct protective effect on atheroma formation independent of serum concentrations of total cholesterol.  相似文献   
995.
Primary tumors of the heart are infrequent at all ages. We present a newborn with hypoxia and a heart murmur, in whom an echocardiogram revealed a large tumor filling the right ventricle and the pulmonary annulus. To maintain pulmonary blood flow, the patency of the ductus arteriosus was achieved by infusion of prostaglandin E1. Successful surgical resection was accomplished. The pathological examination was characteristic of a benign teratoma. The patient remains asymptomatic and has shown no evidence of recurrence of the tumor during a follow-up period of 34 months. This represents the eleventh case of intracardiac teratoma and only the fourth case to undergo successful surgical resection.  相似文献   
996.
李强  徐天任  吕畅  戴衍朋 《药学研究》2020,39(5):261-265
目的 探讨不同产地、不同品种的山楂样品对胰脂肪酶活性的抑制作用。方法 以对硝基苯基丁酸酯作为底物,在405 nm波长测定山楂饮片样品的水提物对胰脂肪酶体外活性。结果 各批次山楂样品对胰脂肪酶活性具有一定的抑制作用。结论 山楂可用于预防和治疗肥胖症;胰脂肪酶活性可作为山楂饮片等级划分的生物效应指标。  相似文献   
997.
998.
999.
1000.

Many veterans receive behavioral health care services from providers in their communities. The Community Provider Toolkit (the Toolkit) is a website developed by the National Center for PTSD and the Department of Veterans Affairs intended to provide community mental health care providers with key veteran-focused educational resources. This mixed-methods study examined the potential impact of the Toolkit on provider knowledge and behaviors. Sixty-four clinicians in the community who currently or plan to provide services to veterans were surveyed. The majority of providers found the website useful and easy to navigate. After visiting the site, many providers found additional online and educational resources that they would add to a hypothetical treatment plan. Forty-five providers completed a 1-month follow-up survey focused on use of the Toolkit. Results indicate that the Toolkit may be a valuable tool for increasing provider knowledge about veteran-specific resources.

  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