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   1413051篇
  免费   97877篇
  国内免费   2291篇
耳鼻咽喉   19955篇
儿科学   46147篇
妇产科学   41086篇
基础医学   206645篇
口腔科学   40186篇
临床医学   115973篇
内科学   281436篇
皮肤病学   30379篇
神经病学   110304篇
特种医学   53388篇
外国民族医学   367篇
外科学   212768篇
综合类   27171篇
现状与发展   1篇
一般理论   321篇
预防医学   108611篇
眼科学   32857篇
药学   108437篇
  1篇
中国医学   3018篇
肿瘤学   74168篇
  2018年   16076篇
  2017年   11567篇
  2016年   12682篇
  2015年   14505篇
  2014年   19220篇
  2013年   29350篇
  2012年   42118篇
  2011年   45038篇
  2010年   25673篇
  2009年   23283篇
  2008年   42359篇
  2007年   45868篇
  2006年   46149篇
  2005年   45052篇
  2004年   43104篇
  2003年   41623篇
  2002年   40867篇
  2001年   61732篇
  2000年   63632篇
  1999年   53779篇
  1998年   14793篇
  1997年   13178篇
  1996年   13417篇
  1995年   12658篇
  1994年   12017篇
  1992年   42710篇
  1991年   41867篇
  1990年   41422篇
  1989年   40012篇
  1988年   37375篇
  1987年   36495篇
  1986年   34912篇
  1985年   33235篇
  1984年   24724篇
  1983年   21486篇
  1982年   12744篇
  1981年   11256篇
  1979年   23617篇
  1978年   16540篇
  1977年   14370篇
  1976年   13584篇
  1975年   14948篇
  1974年   17579篇
  1973年   17028篇
  1972年   16220篇
  1971年   15132篇
  1970年   14045篇
  1969年   13636篇
  1968年   12901篇
  1967年   11290篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
Selective protection of the normal host tissues from the toxic effects of anticancer agents would allow the use of higher, probably more effective, doses of the drugs. It has been demonstrated that delayed high-dose uridine administration after 5-fluorouracil decreases the extent of myelosuppression and causes faster regeneration of the bone marrow. We studied the biochemical consequences of the gastrointestinal toxicity caused by 5-fluorouracil and the potential of high-dose uridine treatment to influence these adverse effects. 5-Fluorouracil caused dose-related decreases in the biochemical parameters (thymidine kinase, sucrase, maltase, alkaline phosphatase) selected as early markers of the impaired metabolic activity of the intestinal mucosa. The nadir of the biochemical changes was reached between 24 h and 72 h after 5-fluorouracil treatment, and complete regeneration of the mucosa took 6–7 days. Delayed high-dose uridine administration failed to mitigate the severity of the gastrointestinal damage that ensued after 5-fluorouracil treatment, but caused significantly earlier regeneration of the mucosa.  相似文献   
142.
Spinal epidural hematoma. Report of a case and review of the literature   总被引:3,自引:0,他引:3  
We report the case of a thoracic epidural hematoma at the T7-T9 level which occurred after placement of spinal epidural catheter for continuous anaesthesia in acute pancreatitis. The male patient felt a sudden back pain after six days of successful analgesia and became paraplegic 24 hours afterwards. An emergency laminectomy and removal of the hematoma were performed; however, the patient recovered only incompletely.We discuss the clinical signs and symptoms of spinal epidural hematoma as well as its diagnostics and therapy. The controversial views from the literature concernings its etiology are critically reviewed.  相似文献   
143.
Transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (TES) of the human motor cortex produce a silent period (SP) following motor evoked potentials (MEPs). The early part of the SP can be explained by decreased alpha motor neuron excitability, whereas the late part is presumably due to suprasegmental mechanisms. In order to determine the level of the suprasegmental contribution to the generation of SPs, we recorded excitatory and inhibitory responses to TMS, TES, and percutaneous electrical brainstem stimulation (PBS) in the voluntarily activated first dorsal interosseous muscle of the hand. Stimulus intensities were set so that PBS and TES induced MEPs with areas equal to or larger than those of MEPs obtained with TMS. This procedure revealed that SPs were 49% and 83% shorter with TES and PBS, respectively, than with TMS. As TMS is more effective than TES or PBS in activating cortical interneurons, these findings support the idea that a significant component of the SP arises from intracortical mechanisms.  相似文献   
144.
Felty's syndrome (FS), the association of rheumatoid arthritis (RA) and idiopathic neutropenia, remains an unexplained phenomenon. HLA-DR4 is found in over 90% of cases. Patients with FS may have a T cell lymphocytosis of CD3+CD8+CD57+ large granular lymphocytes (LGL syndrome). In this study of 47 patients with FS, 19% had clear evidence for LGL expansions, while in total 42% had variable evidence for the LGL syndrome using currently available techniques. Of these T cell expansions, 76% were clonal, as demonstrated by Southern blotting and analysis with T cell receptor (TCR) beta chain constant region probes. This technique may fail to detect clonal populations in some patients. Cytofluorographic analysis using antibodies specific for TCR V beta chains identified patients with clonal LGL expansions with results comparable to those obtained with Southern blotting. No evidence for shared V beta usage among expansions from different patients was seen. The role of LGL in RA and FS is currently unclear, but this technique offers a practical and accessible means of identifying patients with LGL expansions, as a starting point for further investigation.  相似文献   
145.
From 1979 to 1987, 907 patients with non-oat cell carcinoma of the lung were subjected to thoracotomy: of these, 685 (75.5%) underwent radical resection of the lung tumour. The 230 stage IIIa patients were studied in this paper. These were divided into three groups. First group: 93 patients with only local parietal or mediastinal spread without involvement of the mediastinal lymph nodes (T3N0-1M0); the 5-year survival of this group was 35% (44.1% when the ribs and muscles were not affected). A second group of 118 patients had tumour spreading to the mediastinal lymph nodes, but without local involvement (T1-2N2M0): this group had a 5-year survival of 22.3%. The 5-year survival was better in patients without metastases in the subcarinal lymph nodes than in patients with them (23.76% versus 12.89%). Skipping of lymphatic levels was frequent: 37% of patients with metastasis to mediastinal lymph nodes did not have metastases in the lymph nodes of the lung; 10% of tumours removed by lobectomy had metastases in the lymph nodes of the residual lobe. The third group with parietal and lymphatic mediastinal invasion (T3N2M0) had a poor survival (13.5% at 5 years). The author concludes that it is possible to achieve an acceptable 5-year survival in selected cases with metastasis to mediastinal lymph nodes: when the CT scan demonstrated mediastinal lymph nodes larger than 1.5 cm, mediastinoscopy was carried out and, if positive, the patient was judged inoperable.  相似文献   
146.
Serial blood samples were taken at two-hour intervals over a 24-hour period from 25 premenopausal vegetarians (12 vegans and 13 ovolactovegetarians) and from 21 omnivorous controls. All members of the former group had been on a vegetarian diet for a minimum of three years. The mean proportion of estradiol unbound to blood proteins was similar in both vegetarians (1.26%) and meat eaters (1.16%). However, the amount bound to albumin was significantly raised in vegetarians (50.1% vs. 43.1%, p less than 0.009), whereas that bound to sex hormone-binding globulin (SHBG) was correspondingly lower (48.7% vs. 55.8%, p = 0.01). Mean levels of SHBG were similar in vegetarians (59.9 nmole/l) and omnivores (62.0 nmole/l), as was the total amount of free fatty acid (0.42 mmole/l for both). Within the vegetarian group, no differences were detected between vegans and ovolactovegetarians.  相似文献   
147.
This article explains how the concept of health for all developed within the context of the history of the World Health Organization (WHO). By the early 1970s a new idea was taking shape in WHO. Medical services were failing to reach vast numbers. Health would have to emerge from the people themselves. In the heat of discussion the new strategy was clarified and given a name--primary health care (PHC). An ambitious target was set for it--no less than health for all by the year 2000. It was decided that the community itself had to be involved in planning and implementing its own health care. A new type of health worker was called for, chosen by the people from among themselves and responsible to the community but supported by the entire health system. In virtually all countries, the emphasis on curative care would have to be balanced by an equal emphasis on prevention. Almost 90% of WHO's Member States were prepared to share with one another detailed information about the problems facing their health systems. Industrial countries were beginning to realize that sophisticated medical technology was no guarantee of good health and that health for all through PHC offered an alternative. Millions of health workers have been trained, extending services to low-income groups that had no access to modern health care. Among health professionals, lack of understanding of the PHC concept and insufficient concern for social equity remain the principal constraints. Another problem is that expenditure on health care tends to be viewed as a drain on scarce resources rather than as an investment in the nation's future. The mommentum of health for all can be sustained only by governments implementing at home the policies they have collectively agreed on at The World Health Assembly in Geneva.  相似文献   
148.
149.
150.
Internal eye wall resection in the management of uveal melanoma   总被引:3,自引:0,他引:3  
Twenty patients with presumed uveal melanoma underwent internal eye wall resection. It was the primary procedure in 13 patients who had tumours within 2 disc diameters of the optic nerve head and was combined with external resection in the remainder. Malignant melanoma was confirmed histologically in 15 patients; the diagnosis was a benign tumour in the other 5. The length of follow-up ranged from 2 to 37 (mean 19) months. In all cases the retina was completely attached at the time of last examination. The visual acuity ranged from 20/40 to hand movements; nine patients had an acuity of 20/400 or better. At the time of writing no metastatic disease or local recurrence had developed in any of the 15 patients in whom malignant melanoma was diagnosed.  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