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   5441篇
  免费   671篇
  国内免费   9篇
耳鼻咽喉   39篇
儿科学   244篇
妇产科学   90篇
基础医学   804篇
口腔科学   171篇
临床医学   690篇
内科学   1244篇
皮肤病学   47篇
神经病学   558篇
特种医学   128篇
外科学   631篇
综合类   157篇
一般理论   5篇
预防医学   493篇
眼科学   67篇
药学   495篇
中国医学   6篇
肿瘤学   252篇
  2021年   99篇
  2020年   51篇
  2019年   76篇
  2018年   100篇
  2017年   77篇
  2016年   73篇
  2015年   97篇
  2014年   106篇
  2013年   175篇
  2012年   241篇
  2011年   251篇
  2010年   126篇
  2009年   130篇
  2008年   251篇
  2007年   248篇
  2006年   242篇
  2005年   264篇
  2004年   247篇
  2003年   262篇
  2002年   244篇
  2001年   168篇
  2000年   142篇
  1999年   139篇
  1998年   61篇
  1997年   71篇
  1996年   52篇
  1995年   45篇
  1994年   51篇
  1993年   48篇
  1992年   98篇
  1991年   127篇
  1990年   99篇
  1989年   106篇
  1988年   103篇
  1987年   118篇
  1986年   90篇
  1985年   90篇
  1984年   71篇
  1983年   65篇
  1982年   54篇
  1980年   49篇
  1979年   82篇
  1978年   76篇
  1977年   58篇
  1975年   44篇
  1974年   50篇
  1973年   44篇
  1972年   48篇
  1970年   44篇
  1969年   45篇
排序方式: 共有6121条查询结果,搜索用时 15 毫秒
1.
The cephalometric measurement known as Wits appraisal (AOBO) was studied to determine its importance in diagnosis, treatment, and prediction of treatment success. The Wits appraisal is used primarily to identify unreliable ANB values (those that do not accurately reflect the degree of horizontal jaw discrepancy, ie, those that differ greatly from the AOBO value). Therefore, differences between AOBO and ANB also were evaluated. Because neither measurement alone can assess jaw discrepancies with total accuracy, they were combined, plotted on a scattergram, and divided into equal zones to create a new index of horizontal skeletal discrepancies and treatment predictability. Pretreatment values correspond to treatment difficulty, and posttreatment values correspond to the effectiveness of treatment. Treatment time for each zone also was evaluated. We were able to draw several conclusions from this study. First, combining AOBO and ANB values results in a more accurate measurement of treatment difficulty. These combined values also can be used to predict both treatment time and the success of treatment for horizontal discrepancies. Second, the AOBO value predicts variations in treatment time at each ANB value. Finally, adding ANB and AOBO values and then dividing the total yields zones that represent statistically significant differences in treatment times and percentages of success. The zones also correlate with the difference between AOBO and ANB measurements.  相似文献   
2.
A crossover double-blind controlled trial was performed on 36 patients with rheumatoid arthritis to assess the necessity for serum salicylate monitoring in determining optimal dosage. There was no clinically or statistically significant increase in the clinical improvement of patients associated with serum monitoring but potentially toxic serum levels occurred without tinnitus when serum monitoring was not used.  相似文献   
3.
4.
Through understanding the relationships between the previous day's (Sunday) demand and the remaining days' demand, a prediction model can be constructed. The staff level can be determined based on this prediction model. This model can also be applied in different hospital units or a staff environment other than hospitals.  相似文献   
5.
Two sets of factors will ultimately influence the outcome of the burned upper extremity. The first set of factors is the depth and severity of the burn. The second set is the group of complications of the burn injury attributable to edema, inflammation, immobility, and malposition. An awareness of the potential pitfalls that follow burn injury has resulted in improved primary care and a lessening of deformity. Progressive acute care with topical chemotherapy, early motion, thoughtful splinting, and timely burn wound closure are essential to reduce the need for secondary operations. Reconstructive efforts should be tailored to the individual needs of the patient. These procedures should be carefully planned with a view toward balancing aesthetic and functional considerations and minimizing the time required for rehabilitation.  相似文献   
6.
OBJECTIVE: To identify the possible contribution of electromyogram (EMG) to scalp electroencephalogram (EEG) rhythms at rest and induced or evoked by cognitive tasks. METHODS: Scalp EEG recordings were made on two subjects in presence and absence of complete neuromuscular blockade, sparing the dominant arm. The subjects undertook cognitive tasks in both states to allow direct comparison of electrical recordings. RESULTS: EEG rhythms in the paralysed state differed significantly compared with the unparalysed state, with 10- to 200-fold differences in the power of frequencies above 20 Hz during paralysis. CONCLUSIONS: Most of the scalp EEG recording above 20 Hz is of EMG origin. Previous studies measuring gamma EEG need to be re-evaluated. SIGNIFICANCE: This has a significant impact on measurements of gamma rhythms from the scalp EEG in unparalysed humans. It is to be hoped that signal separation methods will be able to rectify this situation.  相似文献   
7.
Determining sufficient staff levels and providing quality, economical and efficient service is a problem that is difficult for some staffing managers to solve. The objectives in this paper are to derive a stochastic model for determining the necessary staff levels in various service environments such as hospitals, banks, or in manufacturing settings where the demand for a good staff is erratic. In order to assess the proper staff levels, an equation must be used which involves previous service demand hours that are considered as a distribution integrated within the statistical capability scale distribution. The most important property of this staffing model is that the results are independent of the mix of the jobs, the variation of the in-service time for jobs, and the stationary or nonstationary job arrival rate.  相似文献   
8.
Epidemiological data from the United States of America (USA) indicate that the incidence and mortality of prostate cancer is higher among Black African-American men (AAM) than among White (Caucasian) American men (CAM). Earlier studies suggesting that prostate cancer is relatively rare among indigenous Black men in Africa are probably flawed by underreporting because recent studies indicate that the incidence rates among Black men are similar to those of White men living in Africa. The higher incidence of prostate cancer among AAM has been ascribed to racial differences in genetic susceptibility, dietary factors, or androgen metabolism. However, it may also be due to registration artefacts because in Africa the reported incidence rates of prostate cancer in different countries correlate directly with the per capita gross national product, suggesting improved access to medical facilities is responsible for higher reported incidence rates.

The greater prostate cancer mortality among AAM may result from higher tumour grade and stage and higher serum PSA at presentation, but it has also been suggested that prostate cancer is biologically more aggressive in AAM than in CAM. However, recent studies indicate that tumour grade and stage and serum PSA at presentation are similar in the races, with no difference in survival after multivariate analysis controlling for pretreatment cancer severity. This suggests that the higher prostate cancer mortality among AAM results from socio-economic factors and limited access to healthcare. Black men living inside as well as outside of Africa still tend to present with locally advanced or metastatic prostate cancer due to lack of early detection programmes.  相似文献   

9.
10.
Urogenital infections are established as hazards to male fertility. Various pathophysiological hypotheses have evolved from experimental and clinical studies, facilitating explanation of the effects of bacteria and immunological events on reproductive tissues. Numerous current studies have identified and evaluated infectious mediators accounting for specific molecular events in urogenital infections. Valuable studies can be expected to appear in the future due to improvements in diagnostic procedures and new classifications of urogenital infections.  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