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   1263899篇
  免费   94819篇
  国内免费   1578篇
耳鼻咽喉   16314篇
儿科学   41001篇
妇产科学   34947篇
基础医学   189419篇
口腔科学   34732篇
临床医学   117757篇
内科学   247821篇
皮肤病学   27278篇
神经病学   101848篇
特种医学   46769篇
外国民族医学   265篇
外科学   178584篇
综合类   25749篇
现状与发展   3篇
一般理论   568篇
预防医学   104655篇
眼科学   28044篇
药学   92558篇
  7篇
中国医学   2022篇
肿瘤学   69955篇
  2018年   13530篇
  2017年   10392篇
  2016年   11324篇
  2015年   13079篇
  2014年   18000篇
  2013年   27480篇
  2012年   37574篇
  2011年   39968篇
  2010年   23054篇
  2009年   22253篇
  2008年   37760篇
  2007年   40385篇
  2006年   39966篇
  2005年   39104篇
  2004年   37552篇
  2003年   35959篇
  2002年   34870篇
  2001年   56031篇
  2000年   57043篇
  1999年   48099篇
  1998年   13402篇
  1997年   12223篇
  1996年   12645篇
  1995年   11914篇
  1994年   11110篇
  1993年   10399篇
  1992年   38202篇
  1991年   37672篇
  1990年   36446篇
  1989年   35260篇
  1988年   32693篇
  1987年   32029篇
  1986年   30525篇
  1985年   28787篇
  1984年   21942篇
  1983年   19193篇
  1982年   11364篇
  1981年   10321篇
  1979年   20945篇
  1978年   15394篇
  1977年   12791篇
  1976年   11846篇
  1975年   12810篇
  1974年   15588篇
  1973年   15362篇
  1972年   14512篇
  1971年   13552篇
  1970年   12786篇
  1969年   12065篇
  1968年   11231篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
Several investigators have suggested that microcomputers might serve as useful external aids for memory-impaired patients. However, knowledge of basic computer vocabulary may be necessary for patients to use and benefit from a microcomputer. The present paper describes a procedure, the method of vanishing cues, which facilitated the acquisition of computer-related vocabulary in four memory-impaired patients. The method involves the systematic reduction of letter fragments of to-be-learned words across trials. Although learning was slow and strongly dependent on first-letter cues, all patients acquired a substantial amount of the vocabulary and eventually were able to produce the target words in the absence of fragment cues. Further, they retained the vocabulary over a 6-week interval and showed some transfer of the knowledge they had acquired. These findings suggest that memory-impaired patients may eventually be able to use a microcomputer as a prosthetic device.  相似文献   
993.
After resection at birth of an accessory left foot, a white male infant was followed up for a slowly enlarging posterior calf mass of the same leg. When the patient was 8 years old, the mass was thought to have enlarged sufficiently to warrant excisional biopsy. Histologic examination of the tumor was consistent with the diagnosis of a dermoid cyst, revealing a lesion lined with stratified squamous epithelium and containing cutaneous adnexal structures represented by eccrine sweat glands. A congenital dermoid in the extremities is unusual. The prognosis following removal is good, and recurrence is rare.  相似文献   
994.
Fetal beta-endorphin release has been associated with fetal hypoxia. The purpose of this study was to assess the degree of uterine blood flow reduction needed to elicit fetal beta-endorphin release in the sheep since there is a large reserve of oxygen supply to the fetus. Uterine blood flow was reduced by 26 +/- 2, 46 +/- 3 and 66 +/- 2%, producing fetal oxygen content concentrations of 5.7 +/- 0.6, 4.4 +/- 0.7 and 2.6 +/- 0.3 ml/dl, respectively. Although fetal oxygen concentrations were significantly decreased in the groups with a reduction in uterine blood flow of 46 and 66%, beta-endorphin was elevated only in the latter group. It is speculated that fetal beta-endorphin is released at a level of hypoxia which leads to a decrease in fetal oxygen consumption. A reduction in uterine blood flow of 66% appears to produce a stressful environment for the fetus as measured by fetal plasma beta-endorphin levels.  相似文献   
995.
A randomized clinical trial was performed to compare the efficacy of bilateral oophorectomy with that of tamoxifen at a dose of 10 mg twice daily in premenopausal women with metastatic breast cancer, and to examine the efficacy of each as a crossover treatment. Initial treatment responses were seen in ten of 27 patients (37%) treated with oophorectomy and seven of 26 patients (27%) treated with tamoxifen. The difference was not statistically significant. Crossover responses were seen in five of 15 patients (33%) treated with oophorectomy, including three responses in ten prior tamoxifen nonresponders; and two of 18 patients (11%) treated with tamoxifen. Time to progression distributions were not significantly different during initial treatment, and no significant differences in survival were noted. Thus, there was no overall disadvantage to the use of tamoxifen as opposed to oophorectomy as initial hormonal therapy, and a failure to respond to tamoxifen did not preclude a response to subsequent oophorectomy. Exploratory data analysis within subsets indicated consistent differential treatment effects in the visceral dominant patients. Of the 16 such patients treated with oophorectomy, eight (50%) experienced objective responses but there were no responses in the 14 patients treated with tamoxifen. In the nine visceral dominant crossover patients who had not responded to initial tamoxifen, three (33%) subsequently responded to oophorectomy. Time to progression distributions within the visceral dominant subset appeared to be better for the patients treated initially with oophorectomy. However, one must be very cautious in drawing conclusions from exploratory subset analyses, especially with the small sample size. Further studies would be required to test any hypothesis of differential organ site responsiveness.  相似文献   
996.
Nurses must frequently make ethical decisions. These decisions require judgment, knowledge, and skills. This article will provide one framework for ethical decision making and provide several examples of the process.  相似文献   
997.
998.
999.
The adequate treatment of methicillin-resistant Staphylococcus aureus (MRSA) osteomyelitis has intrigued clinicians for some time. As the resistance of these pathogens, coupled with the increase in community-acquired cases, continues steadily to rise, clinicians are finding it useful to employ multi-modal approaches for efficacious treatment. The authors present a single case report of a patient with recurrent MRSA osteomyelitis, lumbar paraspinal and epidural abscess. He was found to have decreased muscle strength and was hyporeflexic in the involved extremity. Serum testing demonstrated MRSA bacteremia. Neuroimaging studies revealed evidence of paraspinal abscess and a presumed herniated nucleus pulposus at the L5/S1 interspace with significant nerve root compromise. Despite antimicrobials, his symptoms persisted, necessitating surgical exploration. At surgery, paraspinal and epidural abscesses were encountered and debrided; however, no herniated disc was visualized. This case demonstrates the diagnostic and therapeutic dilemmas with which these lesions present. We postulate that the MRSA osteomyelitis/discitis pathogens were walled off in the disc space and subsequently inoculated the soft tissues with ensuing bacteremia. We concur that antimicrobial treatment should be the first line of therapy for these patients; however, surgical debridements and cautious spinal instrumentation should be employed where appropriate.  相似文献   
1000.
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