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   866812篇
  免费   70988篇
  国内免费   1847篇
耳鼻咽喉   12827篇
儿科学   24884篇
妇产科学   25253篇
基础医学   124825篇
口腔科学   25593篇
临床医学   75654篇
内科学   165422篇
皮肤病学   17111篇
神经病学   70862篇
特种医学   35439篇
外国民族医学   173篇
外科学   136565篇
综合类   24729篇
现状与发展   2篇
一般理论   263篇
预防医学   67475篇
眼科学   20557篇
药学   64940篇
中国医学   1594篇
肿瘤学   45479篇
  2018年   7404篇
  2015年   7803篇
  2014年   11199篇
  2013年   16925篇
  2012年   22960篇
  2011年   24061篇
  2010年   13999篇
  2009年   13173篇
  2008年   22785篇
  2007年   24869篇
  2006年   24691篇
  2005年   24337篇
  2004年   23910篇
  2003年   23026篇
  2002年   22104篇
  2001年   35967篇
  2000年   36585篇
  1999年   31005篇
  1998年   9271篇
  1997年   8586篇
  1996年   8515篇
  1995年   8044篇
  1994年   7748篇
  1992年   26764篇
  1991年   26193篇
  1990年   25713篇
  1989年   24776篇
  1988年   23312篇
  1987年   22971篇
  1986年   21811篇
  1985年   21167篇
  1984年   16464篇
  1983年   14054篇
  1982年   8891篇
  1981年   8246篇
  1980年   7715篇
  1979年   16809篇
  1978年   12152篇
  1977年   10238篇
  1976年   9363篇
  1975年   10186篇
  1974年   12694篇
  1973年   12188篇
  1972年   11573篇
  1971年   10721篇
  1970年   10257篇
  1969年   9959篇
  1968年   8937篇
  1967年   8257篇
  1966年   7678篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
SUMMARY. Samples from 1828 donations were screened for anti-HBc at seven sites in the UK using kits supplied by 10 manufacturers. Only 10 (0.55%) donations were considered to have true anti-HBc reactivity and these were detected by all 10 kits. Additional markers of HBV infection were found in nine of these 10 donations. Additional reactives were found by all kits, the number ranging from 1 to 43.
In the four more specific kits, the 10 true reactives were clearly distinguished from the 'false reactives' by the strength of the reaction. It is concluded that the reliance on a single ELISA test for anti-HBc diagnosis is unwise. The use of a second test known to be more specific than the screening ELISA is recommended.  相似文献   
62.
63.
PCP and related compounds inhibit 3H-mazindol binding to the cocaine receptor on dopamine transporters. The relative potencies of these compounds are such that some of the behavioral effects of PCP could be related to its action at the cocaine receptor; however, the affinity of PCP at the cocaine site (Ki = 1.59 microM) is less than its affinity at its own receptor (Ki about 0.12 microM). More data will be needed to conclusively implicate the cocaine receptor in the action of PCP.  相似文献   
64.
65.
66.
Treatment versus no treatment in chronic open angle glaucoma   总被引:1,自引:0,他引:1  
In a controlled randomized study 15 patients (20 eyes) with chronic open angle glaucoma and visual field defects were followed by greater than 1 year, 12 of them were followed for 3 years. Half of the group were untreated controls, the other half treated with pressure reducing medical therapy. At least 5 consecutive computerized visual fields were recorded (COMPETER) on each eye, and the linear regression coefficient was calculated. With the reservation for uncontrolled compliance no significant difference in the line of favourable effect of pressure reduction could be spotted, in spite of an average pressure reduction in the treated group of 4 mmHg. More important than this result, which is open to criticism for the smallness of the material, uncontrolled compliance etc, is the lesson that a randomized experiment with treated and non-treated glaucoma cases carried out in accordance with the Helsingfors convention is hardly feasible.  相似文献   
67.
68.
Polyploidization and centrosome hyperamplification in inflammatory bronchi   总被引:1,自引:0,他引:1  
OBJECTIVE AND DESIGN: Inflammatory and tumorous bronchi were screened in order to obtain new tumor relevant cytogenetic parameters. MATERIAL OR SUBJECTS: Bronchial cells of 32 patients were cultivated by standard cell culture procedures. METHODS: Tetraploidy and aneuploidy was determined by enumeration of chromosome 7 and 8 versus the number of centrosomes. The resulting data were correlated with histopathological data. RESULTS: Tetra- and aneuploidy of epithelial cells were detectable in 76% of tumor cell cultures, 75% of high grade inflammatory tissues and 40% of non- and low grade-inflammatory tissues. Additionally, we observed centrosome hyper-amplification and multipolar mitoses not only in the tumor but also in the early stages of inflammation. CONCLUSION: Inflammatory bronchi already show tumor-specific features and may consequently represent the preliminary genetic stage of cancer development in bronchi.  相似文献   
69.
OBJECTIVES: The incidence of bacterial microleakage, pulp inflammation and necrosis associated with dentine etching treatments prior to restoration are not known. Consequently, to resolve some of the controversy surrounding the effects and importance of vital dentine etching, the authors investigated these factors. METHODS: 110 standardised class V cavities were cut into buccal dentine, without exposing the pulp of teeth scheduled for extraction for orthodontic reasons. Cavities were either left unetched, or etched with the non-equivalent treatments of phosphoric acid gel for 60s or Ethylenediaminetetraacetic acid (EDTA) for 30s, prior to placement of composite resin. Teeth were collected and pulp responses were evaluated according to ISO guidelines, using pathohistomorphometric analysis and ANOVA statistics. RESULTS: Etching was found to be correlated to bacterial microleakage (p=0.0001) and tertiary dentine formation (p=0.0023). Bacterial microleakage was correlated to inflammatory activity (p=0.0001). The frequency of bacterial microleakage was: no etching (65%), EDTA (51%) and phosphoric acid (PA) (20%). SIGNIFICANCE: Vital dentine etching treatment is of extreme importance for the placement of RC to minimise bacterial microleakage. PA etching proved to be more effective at preventing bacterial microleakage than non-etching, and etching with EDTA.  相似文献   
70.
The infertility distress scale (IBS) has been designed to assess the stress perceived by andrological patients resulting from infertility. This review presents findings from different studies with a total of 769 patients. The scale consists of eight items. The stability of scores is very high even for a mean follow-up of 2 years. The scale correlates highly with an already validated measure of infertility distress. Correlations with measures of depressiveness are in the low to medium range. All in all, the psychometric results indicate that the IBS is a factor-stable, reliable and valid instrument for assessing chronic infertility distress in andrological patients. After the presentation of normative data, the usefulness of the IBS as a screening instrument for identifying highly distressed patients is discussed. Findings supporting the scale's sensitivity to change are also presented. The scale is a useful tool in clinical practice as well as in research.  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