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   41347篇
  免费   2386篇
  国内免费   161篇
耳鼻咽喉   252篇
儿科学   1339篇
妇产科学   725篇
基础医学   3264篇
口腔科学   568篇
临床医学   2524篇
内科学   6158篇
皮肤病学   644篇
神经病学   1216篇
特种医学   1183篇
外科学   5162篇
综合类   9554篇
一般理论   9篇
预防医学   7694篇
眼科学   298篇
药学   1726篇
  41篇
中国医学   807篇
肿瘤学   730篇
  2024年   82篇
  2023年   511篇
  2022年   985篇
  2021年   1331篇
  2020年   1091篇
  2019年   3131篇
  2018年   2721篇
  2017年   1573篇
  2016年   753篇
  2015年   803篇
  2014年   2326篇
  2013年   2007篇
  2012年   2211篇
  2011年   2301篇
  2010年   1906篇
  2009年   1626篇
  2008年   1485篇
  2007年   1297篇
  2006年   1211篇
  2005年   796篇
  2004年   601篇
  2003年   493篇
  2002年   337篇
  2001年   297篇
  2000年   266篇
  1999年   240篇
  1998年   187篇
  1997年   180篇
  1996年   128篇
  1995年   134篇
  1994年   111篇
  1993年   53篇
  1992年   24篇
  1991年   32篇
  1990年   23篇
  1989年   18篇
  1986年   17篇
  1985年   852篇
  1984年   1390篇
  1983年   1111篇
  1982年   1099篇
  1981年   1103篇
  1980年   956篇
  1979年   844篇
  1978年   661篇
  1977年   464篇
  1976年   632篇
  1975年   554篇
  1974年   470篇
  1973年   430篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
For planning or co-ordinating health services it is necessary to have reference points for evaluating similar departments in which homogeneous or equivalent activities are carried out. It is also necessary to consider the cost/benefit of the services. The paper presents several new indices of performance which may be applied to this problem and which enable quantitative comparisons to be made between hospitals and between departments. These indices include assessment of electrical hazards and service ability of equipment as well as the ratio of technical support staff to inpatient stay. The indices have been evaluated in a few large hospitals and found to be an effective management tool.  相似文献   
22.
Arterial spasm was induced by application of calcium chloride to the adventitial surface of the rabbit common carotid artery in vivo. Sodium chloride (NaCl) was applied to the contralateral vessel as control. Vessels were fixed in situ by intravascular perfusion after 15 min, 1 hr, or 24 hr and prepared for light and scanning electron microscopy (SEM). With SEM, the luminal surface at the site of calcium application showed severe longitudinal folding accompanied by endothelial desquamation with extensive platelet deposition on exposed subendothelium. The luminal cross-sectional area was reduced by 53 +/- 19.5% after 15 min and by 44 +/- 12% after 1 hr as compared with the contralateral control. Furthermore, the luminal area at the site of calcium application was found to be reduced by 42 +/- 8% after 1 hr when compared with segments of the same vessel distal to the site of calcium application. Blood flow rate, as measured by electromagnetic flow probe, was not reduced. Vessels examined after 24 hr showed a significant increase in luminal cross-sectional area as compared with contralateral control vessels (136 +/- 70%). Control vessels (NaCl) showed no significant change in luminal cross-sectional area and no endothelial desquamation or platelet deposition after 15 min, 1 hr, or 24 hr. Examination of histologic sections showed calcium precipitation within the attached thrombus after 15 min with calcium deposits also adherent to the adjacent luminal aspect of the internal elastic lamina (IEL). By 24 hr, this precipitation extended throughout the media. Marked deposition of leukocytes was seen after 24 hr which showed a preferential attachment for areas of endothelial damage and discontinuity of IEL.  相似文献   
23.
24.
National Taiwan University College of Medicine (NTUCM) introduced small groups of teaching and basic-clinical integrated courses for medical students in 1992. By using computer network and multimedia techniques, this study tried to overcome barriers to learning in small group teaching. The Department of Medical Informatics of NTUCM established campus networking and computer classrooms and provided Internet and intranet network services including mail, netnews, bulletin board systems (BBS), world wide web (WWW), gopher, ftp and local file servers. To implement an interactive learning environment, the authors first tried mail lists, newsgroups and BBS. Next an integrated learning system prototype on the WWW was developed to provide functions including online syllabus, discussion boards simulated to BBS, online talk, interactive case studies, virtual classroom with video on demand (VOD) and Internet medical resources. The results showed that after the medical students completed the required course of medical informatics and had good network access using a network to communicate with each other became a daily practice. In the future, the system will extend to the tutoring of clinical practice and continuing medical education. The authors expect a national medical education network and more international cooperation and exchange.  相似文献   
25.
The Waorani Indians of eastern Ecuador have the highest blood concentration of IgE reported in a human population. Evidence obtained by medical history, physical examination, and immediate hypersensitivity skin tests suggests that pollen allergy and other atopic diseases are rare among the Waorani. A similar association between parasite-induced hyperimmunoglobulinemia-E and a low prevalence of conventional atopic disease has been reported in numerous other tropical populations. Saturation of mast cell IgE receptors with antibodies directed to the parasite and/or other antigens and competitive inhibition of passive binding of pollen allergen-specific IgE is one hypothetical cause of this association. We have tested this interesting conjecture by passively sensitizing the skin of Waorani Indians with serum containing pollen allergen-specific IgE antibodies. Waorani Indians with hyperimmunoglobulinemia-E can be adoptively sensitized with human ragweed or rye grass hyperimmune IgE antisera. This suggests that the cutaneous mast cells of healthy Waorani have active IgE receptors. The high circulating plasma concentrations of IgE in the Waorani do not prevent adoptive cutaneous sensitization with pollen-specific IgE antibodies.  相似文献   
26.
Psychological and neuropsychological aspects of COPD   总被引:2,自引:0,他引:2  
A review of the literature dealing with the effects of chronic obstructive pulmonary disease (COPD) on psychological and neuropsychological functioning indicates that significant emotional and adaptive deficits characterize this patient population. Psychiatric consultation can provide valuable assistance to the primary care physician by reducing emotional distress and correcting dysfunctional attitudes and beliefs. Neuropsychological assessment can elucidate an individual's neurobehavioral resources and deficits.  相似文献   
27.
28.
Comparative nasal absorption of allergens in atopic and nonatopic subjects.   总被引:3,自引:0,他引:3  
Based on sensitization following intranasal antigen administration, previous investigations have suggested greater absorption of allergens through the nasal mucous membranes of atopic than of nonatopic subjects. In this study mucosal absorption was assessed more directly by determining the capacity of allergens applied intranasally to elicit cutaneous Prausnitz-Küstner (P-K) reactions in nonatopic persons as compared with asymptomatic atopic subjects sensitive to other allergens. Two series of reaginic human serum dilutions were injected intracutaneously in recipients backs, and 48 hours later one series was challenged intracutaneously with test allergen. After the responses had been recorded, concentrated allergenic extract was sprayed into the nose and the second series of P-K sites observed for reactivity. Sometimes these P-K sites were rechallenged intracutaneously the following day to determine passive transfer neutralization. Two allergens were studied: bovine ribonuclease (RNase) and peanut extract. Two sera containing peanut reagins and one with RNase antibodies were each used in 10 to 11 atopic and 9 to 11 nonatopic recipients. The atopic group failed to show greater or more rapid absorption of either allergen through the nose based on the highest serum dilution reacting after nasal challenge. the speed of the reaction, the ratio of the titer by nasal challenge to the intracutaneous titer, or passive transfer neutralization. Controls showed that the results were not influenced by systemic absorption of allergen employed for intracutaneous tests. Drinking the amount of peanut extract applied intranasally did not elicit P-K reactions.  相似文献   
29.
Growth of diploid cells from breast cancers   总被引:1,自引:0,他引:1  
Cell cultures were derived from normal and cancerous breast tissues and from metastases by methods that selected for relatively adherent epithelial aggregates. Karyotypic analyses of first or second passage cultures yielded predominantly normal diploid cells. Nonclonal aberrations were more common in tumor-derived than in normal cultures. Three of the cultures that originated from metastases were characterized by abnormal clones. These results support observations based on DNA content, which indicate that a considerable fraction of breast cancers are composed predominantly of diploid cells. They differ greatly from chromosomal findings in long-term cultures of tumor effusions and thus emphasize the karyotypic diversity that can be found in tumors from a single tissue of origin--the breast.  相似文献   
30.
The role of del (11)(p13) as a cause of aniridia, with and without Wilms tumor, is strengthened by demonstration of this chromosome aberration in 3 patients: monozygous twin girls, both of whom have aniridia and mental retardation and one of whom has a Wilms tumor; and an unrelated boy with aniridia and ambiguous genitalia. The break points defining the interstitial deletion for the twins are 11p13 and 11p15.1, while for the boy they are 11p1302 and 11p14.1. These patients and their karyotypes substantiate the critical importance of chromosome band 11p13 (or its hemizygous representation) in the development of aniridia and an associated Wilms tumor diathesis, as had been suggested previously (Riccardi VM, Sujansky E, Smith AC, Francke U, (1978): Pediatrics 61, 604-610).  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