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   200413篇
  免费   39554篇
  国内免费   1076篇
耳鼻咽喉   3422篇
儿科学   6672篇
妇产科学   2878篇
基础医学   19063篇
口腔科学   9688篇
临床医学   36968篇
内科学   46531篇
皮肤病学   10307篇
神经病学   24425篇
特种医学   5501篇
外科学   30725篇
综合类   244篇
现状与发展   40篇
一般理论   32篇
预防医学   17780篇
眼科学   3340篇
药学   6964篇
  5篇
中国医学   1018篇
肿瘤学   15440篇
  2024年   792篇
  2023年   5268篇
  2022年   1360篇
  2021年   4217篇
  2020年   11635篇
  2019年   14139篇
  2018年   15171篇
  2017年   17014篇
  2016年   17934篇
  2015年   17875篇
  2014年   20402篇
  2013年   22822篇
  2012年   7570篇
  2011年   7465篇
  2010年   14800篇
  2009年   13669篇
  2008年   5562篇
  2007年   3688篇
  2006年   4913篇
  2005年   3345篇
  2004年   2764篇
  2003年   2410篇
  2002年   2369篇
  2001年   2661篇
  2000年   1911篇
  1999年   2042篇
  1998年   2202篇
  1997年   2021篇
  1996年   2051篇
  1995年   1766篇
  1994年   1158篇
  1993年   1004篇
  1992年   832篇
  1991年   712篇
  1990年   595篇
  1989年   571篇
  1988年   567篇
  1987年   425篇
  1986年   412篇
  1985年   359篇
  1984年   318篇
  1983年   351篇
  1982年   274篇
  1981年   241篇
  1980年   168篇
  1979年   107篇
  1978年   155篇
  1977年   155篇
  1976年   110篇
  1974年   115篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
The current study was undertaken to evaluate both maxillary and mandibular shape/size changes in children with Class III malocclusions, treated with a functional appliance (removable mandibular retractor). Nonconventional cephalometric methods (Bookstein's shape coordinate analysis, centroid size analysis, and tensor analysis) were applied to a maxillary triangle (T-FMN-A) and to a mandibular triangle (Co-Go-Pg). A group of 30 children with treated Class III malocclusions were compared with a matched group of 30 children with untreated Class III malocclusions. Treatment with the functional appliance produced a significantly increased growth of the maxilla, featuring a more downward and forward displacement of the region of point A and a significantly more upward and forward direction of condylar growth, leading to a “shrinkage” of total mandibular length. The biologic significance of some conventional cephalometric measurements used for the assessment of both maxillary and mandibular position and structure was tested.(Am J Orthod Dentofac Orthop 1997;112:622-33.)  相似文献   
52.
53.
Objectives: This study investigated correlates of dental care use in a representative sample of adults aged 70 and older throughout New England. Methods : Data were collected in in-home interviews and dental examinations. Following Andersen's behavioral model of health services utilization, varied measures of sociodemographic characteristics, dental health attitudes and practices, perceived need for care, and need objectively determined by clinical examination were included as potential correlates. Results : Recency of last visit was associated with positive attitudes toward dental care, regular dental hygiene, and having a usual source of care. Among dentulous subjects, recency of last visit also was related to sex and living arrangements. Frequency of visits for dentulous subjects was associated with the same variables, as well as with age and social class or education, in addition to need for care. For edentulous subjects, only a usual sourse of care and higher social class were associated with more frequent visits. Conclusions : Perceived need and attitudes toward dental care are important influences on use of care. Older persons must be convinced of the importance of regular dental care.  相似文献   
54.
As in all of medicine, there are basic assumptions underlying the present system of dental education and delivery. These basic assumptions are facing challenges due in part to the marked reduction in the incidence of caries and the development of more effective therapies. This current period of time is described as an era of true change, rather than the mere modification of existing technology. Changes are going to occur in a number of areas. The move will be from government to private, from small to large, from generalist to specialist. Since change is inevitable, one can learn about and prepare for the stress of change, the changes happening now, and how to adapt to change. Although many changes are beyond the individual's control, their occurrence may be beneficial.  相似文献   
55.
The purpose of this study was threefold: (1) to report the proportion of dental practitioners adhering to the 1987 Centers for Disease Control (CDC) procedures for using infection control techniques (ICTs); (2) to identify attitudes toward infection control and disease; and (3) to establish whether certain practitioner characteristics or use of certain ICTs were related to willingness to treat HIV-positive patients, willingness to volunteer for an HIV specialty clinic outside of regular practice, vaccination against hepatitis B, and a felt need for a specialty clinic within the practice to treat HIV patients effectively. A survey of approximately 3,800 members of a major metropolitan dental society found that 89 percent of respondents regularly used at least one CDC ICT beyond routine medical histories. Ninety-one percent indicated a moderate to extreme change in attitude toward the risks of infectious diseases and the regular use of ICTs (80.2% identified AIDS as the major factor in this change). Twenty-seven percent indicated that they would knowingly treat HIV-positive patients. No differences were found among practitioners willing to treat HIV-infected patients and those unwilling to treat these patients in terms of adherence to the CDC ICT recommendations for dentists. Statistical association between ICT use and other practitioner response variables are discussed.  相似文献   
56.
Analysis of temporomandibular joints sounds may contribute to the differential diagnosis of temporomandibular joint disorders. In this article an advanced system for the recording of joint sounds is presented. The method proved to be reliable. The problem of filtering out artifacts has been solved to a great extent but not completely. Temporomandibular joint sounds measured with this technique vary considerably in energy, frequency spectrum, and peak-to-peak amplitude over 3 months, as well as within 1 day. These differences seem to reflect natural variations in joint sounds caused by the physical impossibility of performing identical jaw movements. The results indicate that joint sound characteristics do not yet offer a solid basis for inferences concerning the development of temporomandibular joint abnormalities in the clinical setting.  相似文献   
57.
A recent survey of dental schools concluded that current efforts toward remediation are inadequate. A remedial waxing course providing recognition training before production attempts, emphasis on formative self- and peer-evaluation of projects, and application of a highly structured format for ensuring relevant practice had been developed and favorably evaluated previously. The current report follows the progress of two differently trained remedial groups and the remainder of the class in two courses following remediation. On the five subsequent practical examinations analyzed, the experimental group continued to perform at the class mean. On one practical examination, the experimental group significantly outperformed the traditional group (p less than 0.02). For three of the five examinations, the traditional group was significantly outperformed by the class. One of the six students in the experimental group required additional remediation. Of the seven in the traditionally remediated group, one left school and four required additional remediation. An apparent changing remediation pattern in the preclinical training period is described and possible reasons for the change are explored.  相似文献   
58.
59.
Statement of problem. Dental casting alloys are subjected to transient acidity in the oral environment, yet most studies have not investigated the effects of these transient environments on elemental release from alloys. Elemental release is important because it plays a significant role in alloy biocompatibility. Purpose. It was hypothesized that acidic environments would increase elemental release from dental alloys during exposure and after the acidic environment was removed. This hypothesis was based on the known increase in release of nickel from nickel-based alloys in an acidic environment. Material and methods. High-noble, noble, and base metal casting alloys were exposed for 30 minutes to solutions with pH ranging from 1 to 7. Elemental release of representative elements was measured by means of atomic absorption spectrometry during the exposure and in the week after the exposure. This release was compared with elemental release in the week before the exposure. Results. High-noble and noble alloys were resistant to acidic environments. A pH of 4 did not increase elemental release during or after exposure. A pH 1 environment slightly elevated release of Ag, Cu, and Pd in some alloys. However, a Ni-based alloy released large amounts of Ni during the acidic exposure of pH 1 or 4, and more importantly, in the week after the exposure as well. Increased time of exposure to acid did not alter elemental release from noble or high-noble alloys, but markedly increased release from the Ni-based alloy. Conclusions. Transient exposure of casting alloys to an acidic oral environment is likely to significantly increase elemental release from Ni-based alloys, but not from high-noble or noble alloys. (J Prosthet Dent 1998;80:691-8.)  相似文献   
60.
Temporalis muscle transfer is a versatile technique frequetly used for reconstructive procedures in the maxillofacial region. However the thickness of the pedicle may interfere with masticatory function when used anteriorly in the oral cavity. To repair full-length mid-palatal defects in fully dentate patients the flap can be passed through the maxillary sinus and combined with local repair of the soft palate, thus avoiding any occlusal trauma from the posterior teeth.
The operation is a single stage procedure with low morbidity and few complications, and is a useful technique for repairing the large untreated clefts frequently encountered in developing countries. The procedure is used by members of the Australian and New Zealand Association of Oral and Maxillofacial Surgeons Bangladesh Project who have operated in Dhaka teaching hospitals on a regular basis since 1991.  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