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   574185篇
  免费   37314篇
  国内免费   657篇
耳鼻咽喉   7811篇
儿科学   18568篇
妇产科学   14979篇
基础医学   94018篇
口腔科学   16660篇
临床医学   49976篇
内科学   104598篇
皮肤病学   13699篇
神经病学   42506篇
特种医学   21364篇
外国民族医学   64篇
外科学   85630篇
综合类   8698篇
一般理论   151篇
预防医学   42883篇
眼科学   13402篇
药学   44706篇
中国医学   1088篇
肿瘤学   31355篇
  2018年   6292篇
  2017年   4740篇
  2016年   5528篇
  2015年   5746篇
  2014年   7466篇
  2013年   12011篇
  2012年   16086篇
  2011年   17940篇
  2010年   10209篇
  2009年   9014篇
  2008年   17276篇
  2007年   18391篇
  2006年   18475篇
  2005年   17769篇
  2004年   17363篇
  2003年   16704篇
  2002年   16537篇
  2001年   26510篇
  2000年   28146篇
  1999年   22307篇
  1998年   5990篇
  1997年   5190篇
  1996年   5406篇
  1995年   4930篇
  1994年   4637篇
  1992年   16073篇
  1991年   16611篇
  1990年   16703篇
  1989年   16148篇
  1988年   14842篇
  1987年   14687篇
  1986年   13884篇
  1985年   13306篇
  1984年   9963篇
  1983年   8538篇
  1982年   4836篇
  1979年   9700篇
  1978年   7063篇
  1977年   5999篇
  1976年   5833篇
  1975年   6613篇
  1974年   7828篇
  1973年   7351篇
  1972年   7123篇
  1971年   6828篇
  1970年   6312篇
  1969年   6052篇
  1968年   5715篇
  1967年   5155篇
  1966年   4561篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The authors applied combined depth and subdural electrodes in patients with intractable complex partial seizures to detect the precise extent of epileptic foci and functionally map speech-related areas. The medial temporal structures were explored with depth electrodes and the lateral temporal cortex with subdural electrodes. On the speech-dominant side, electrical stimulation was given to demarcate the speech-related areas in the lateral temporal cortex. Based on these data, the extent of surgical resections was tailored to include as much of the epileptogenic areas as possible while preserving the functionally essential zones of the lateral cortex. According to the range of resection, three different approaches were employed for en bloc ablation of the lateral cortex and opening of the inferior ventricle. The results thus acquired have been satisfactory in terms of seizure control and the preservation of speech function.  相似文献   
992.
993.
994.
995.
Osteoporosis and Coronary Atherosclerosis in Asymptomatic Postmenopausal Women   总被引:23,自引:9,他引:14  
Estrogen deficiency is a risk factor for osteoporosis and coronary artery disease. Osteoporosis can be evaluated by measuring bone mineral density (BMD). Coronary atherosclerotic burden can be evaluated by measuring coronary calcium using electron beam computed tomography (EBT) of the heart. We compared coronary calcium scores in 45 asymptomatic postmenopausal women with normal and low BMD. BMD of the lumbar spine and proximal femur was measured by dual X-ray absorptiometry (DXA), and coronary calcium was measured quantitatively by EBT. Women were divided into control, osteopenia, and osteoporosis groups based on the T score of the lumbar spine. Women were similar in age, years since menopause, height, weight, and body mass index (BMI). BMD ± SD (g/cm2) of L1–L4 was 0.96 ± 0.11, 0.83 ± 0.03, and 0.73 ± 0.05, in control, osteopenia, and osteoporosis group, respectively. The total coronary calcium score ± SD (relative units) was 41.9 ± 83.1, 115.1 ± 181.9, and 221.7 ± 355.4 for control, osteopenia, and osteoporosis group, respectively; the score was significantly higher in the osteoporosis than in the control group. This study provides initial data suggesting that women with osteoporosis may have a higher risk of developing coronary atherosclerosis.  相似文献   
996.
997.
Human papillomavirus--a study of male sexual partners   总被引:2,自引:0,他引:2  
Male sexual partners of a cohort of women with genital-tract abnormalities which were associated with human papillomavirus infection were examined for evidence of infection with human papillomavirus. Of the 214 male partners who were examined, 93.5% had visible genital lesions. Of the 196 lesions that were biopsied, 72.5% showed histological evidence of infection with human papillomavirus, and only 20.4% of subjects with histological evidence of human papillomavirus were aware of a lesion. An unexpectedly high proportion (6.1%) of lesions on which a biopsy was performed, particularly those with flat, red, indurated morphology, also showed histological evidence of penile intraepithelial neoplasia. This was not significantly more common among the partners of the women with cervical intraepithelial neoplasia than it was among the partners of the women with other evidence of genital human papillomavirus infection. Penile intraepithelial neoplasia was significantly (P less than 0.001) more common among subjects with no history of non-genital warts. We conclude that the male partners of women with human papillomavirus-associated lesions are very likely to be infected with human papillomavirus, and thus may act as a significant reservoir for the reinfection of their female partners. As the awareness of human papillomavirus-associated lesions was low among the male partners, colposcopic examination and treatment of their male partners, and/or barrier contraception, may be a necessary part of the management of women who are undergoing treatment for human papillomavirus-associated genital disease.  相似文献   
998.
999.
1000.
We studied the effects of calcium on transparency in homogenates of cortical and nuclear cells from calf lenses. Calcium was mixed into samples of homogenate to final concentrations between 0 and 50 mM and the transparency of the calcium-treated homogenates was measured using laser transmittance. In the presence of 10 mM calcium, the transmittance of cortical homogenate decreased 50% while the nuclear homogenate lost less than 4% transmittance after 24 h at 37 degrees C. To better understand the contribution of cytoplasm and membranes to opacity, the nuclear and cortical homogenates were centrifuged to separate membranes from the cytoplasm. When 10 mM calcium was added to cortical homogenate which was then centrifuged, the transmittance of the membrane fraction decreased nearly 60%, while the fraction without membrane decreased only 10%. The strong effect of calcium on the membrane fraction was accompanied by an increase in specific gravity of membranes from 1.23 to 1.32. Ten- and 20 mM calcium had no effect on transparency of membranes or cytoplasm separated from nuclear homogenate, and 50 mM calcium produced only a slight opacity. The results indicate that an effect on membrane-protein interactions may be important in the loss of transparency produced by calcium in cells of lens cortex.  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