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   42724篇
  免费   3401篇
  国内免费   565篇
耳鼻咽喉   523篇
儿科学   1075篇
妇产科学   919篇
基础医学   5550篇
口腔科学   670篇
临床医学   4466篇
内科学   8779篇
皮肤病学   707篇
神经病学   3625篇
特种医学   1777篇
外国民族医学   3篇
外科学   6640篇
综合类   1418篇
现状与发展   1篇
一般理论   53篇
预防医学   3014篇
眼科学   852篇
药学   2719篇
  4篇
中国医学   372篇
肿瘤学   3523篇
  2023年   476篇
  2022年   954篇
  2021年   1857篇
  2020年   992篇
  2019年   1410篇
  2018年   1601篇
  2017年   1187篇
  2016年   1174篇
  2015年   1492篇
  2014年   1939篇
  2013年   2268篇
  2012年   3460篇
  2011年   3460篇
  2010年   1939篇
  2009年   1556篇
  2008年   2359篇
  2007年   2401篇
  2006年   2177篇
  2005年   2012篇
  2004年   1749篇
  2003年   1487篇
  2002年   1274篇
  2001年   637篇
  2000年   547篇
  1999年   566篇
  1998年   307篇
  1997年   282篇
  1996年   315篇
  1995年   261篇
  1994年   189篇
  1993年   172篇
  1992年   310篇
  1991年   298篇
  1990年   269篇
  1989年   254篇
  1988年   229篇
  1987年   205篇
  1986年   197篇
  1985年   199篇
  1984年   176篇
  1983年   154篇
  1982年   153篇
  1981年   135篇
  1980年   113篇
  1979年   142篇
  1978年   136篇
  1977年   79篇
  1975年   68篇
  1974年   87篇
  1973年   67篇
排序方式: 共有10000条查询结果,搜索用时 197 毫秒
101.
Even though continued smoking by cancer patients adversely affects survival and quality of life, about one third of patients who smoked prior to their diagnosis continue to smoke after their diagnosis. The implementation of smoking cessation treatments for cancer patients has been slowed by the lack of data on correlates of tobacco use in this population. Thus, this longitudinal study assessed demographic, medical, addiction, and psychological predictors of tobacco use among 74 head, neck, and lung cancer patients. Multivariable binary logistic regression analyses, with outcome categorized as smoker or nonsmoker, indicated that the likelihoodthat patients would be a smoker was associated with lower levels of perceived risk and a higher level of quitting cons. Multivariable nominal logistic regression, with outcome classified as continuous smoker, continuous quitter, relapser, or follow-up quitter, indicated that: (a) patients categorized as continuous smokers reported significantly lower quitting self-efficacy than follow-up quitters and continuous quitters, (b) relapsers reported a significantly lower level of quitting self-efficacy than either follow-up quitters or continuous quitters, and (c) continuous smokers exhibited a significantly lower level of risk perceptions than continuous abstainers. These findings can be useful for the development and evaluation of treatments to promote smoking cessation among cancer patients. Support for this study was provided by National Institutes of Health Grants CA57708, CA06927, CA88610, CA95678, and CA76644.  相似文献   
102.
One of the advantages of polyurethane foam-covered prostheses has been that in the first 5 to 10 years after their use, the amount of capsular contraction was found much less than when similar ``slick' prostheses were used. Another advance was their fixation to the surrounding tissue thus giving a more natural appearance and movement with the muscles when the arms were moved in any direction. The formation of a thick capsule also acted as a protection against gel granuloma due to rupture of the prosthesis and has been thought to be a factor in the lower capsule contraction rate. The greatest disadvantage has been that its removal was extremely difficult and this has continued up until the technique described in this paper has been introduced.  相似文献   
103.
S Law  M Fok  K M Chu    J Wong 《Annals of surgery》1997,226(2):169-173
OBJECTIVE: The objective of this study was to compare the hand-sewn and stapled methods in esophagogastric anastomosis. SUMMARY BACKGROUND DATA: After esophageal resection for cancer, the relative merits of the hand-sewn and the stapled methods of esophagogastric anastomosis, especially regarding leakage and stricture rates, have not adequately been studied. METHODS: A prospective randomized controlled trial was undertaken in 122 patients with squamous cell cancer of the thoracic esophagus who underwent a Lewis-Tanner esophagectomy. Patients were stratified according to esophageal size, based on the diameter of the divided esophagus (< or > or = 30 mm) and then were randomized to have either a hand-sewn or a stapled anastomosis. RESULTS: The mean total operating times (standard error of the mean) when the hand-sewn and the stapled methods were used were 214 (4) minutes and 217 (3.4) minutes, respectively (p = not significant [NS]). The respective in vivo proximal resection margins (standard error of the mean) were 8 (0.4) cm and 7.6 (0.4) cm (p = NS). Leakage rates were 1.6% and 4.9% (p = NS). Excluding hospital deaths, patients with leakage or anastomotic recurrence, and those who received radiation therapy to histologically infiltrated resection margin, anastomotic stricture was found in 5 (9.1%) of 55 patients in the hand-sewn group and 20 (40%) of 50 in the stapler group (p = 0.0003). The difference in stricture rates was significant in small as well as large esophagi. Anastomotic recurrence developed in only one patient in each group. CONCLUSIONS: The authors conclude that both methods were safe, but the stapled technique resulted in more stricture formation.  相似文献   
104.
目的:介绍65例颅内肿瘤显微外科手术治疗经验;方法:本组患者65例,根据肿瘤部位、大小、性质,选择合适的手术入路,采用显微手术切除肿瘤;结果:全切53例,部分切除12例,无手术死亡;术后并发视神经麻痹1例,面神经并动眼神经麻痹1例,三叉神经麻痹1例,舌咽神经麻痹1例,偏瘫5例,无其他手术并发症;结论:正确的手术思路、合适的手术入路是手术成功的基础;采用显微外科手术技术是提高全切率、减少并发症的关键。  相似文献   
105.
106.
无创性动态血压(ABPM)能较客观地反映血压水平及其昼夜变化规律,对高血压病的诊断、指导用药、药物疗效的评定以及预后评估等均有较大价值。本文对ABPM的发展及临床应用等问题进行综述。  相似文献   
107.
108.
A system for assaying human interchromosomal recombination in vitro was developed, using a cell line containing two different mutant thymidine kinase genes (TK) on chromosomes 17. Heteroalleles were generated in the TK+/+ parent B-lymphoblast cell line WIL-2 by repeated exposure to the alkylating nitrogen mustard ICR-191, which preferentially causes +1 or -1 frameshifts. Resulting TK-/- mutants were selected in medium containing the toxic thymidine analog trifluorothymidine. Mutations were characterized by exon-specific polymerase chain reaction amplification and direct sequencing. In two lines, heterozygous frameshifts were located in exons 4 and 7 of the TK gene separated by approximately 8 kilobases. These lines undergo spontaneous reversion to TK+ at a frequency of less than 10(-7), and revertants can be selected in cytidine/hypoxanthine/aminopterin/thymidine medium. The nature and location of these heteroallelic mutations make large deletions, rearrangements, nondisjunction, and reduplication unlikely mechanisms for reversion to TK+. The mode of reversion to TK+ was specifically assessed by DNA sequencing, use of single-strand conformation polymorphisms, and analysis of various restriction fragment length polymorphisms (RFLPs) linked to the TK gene on chromosome 17. Our data suggest that a proportion of revertants has undergone recombination and gene conversion at the TK locus, with concomitant loss of frameshifts and allele loss at linked RFLPs. Models are presented for the origin of two recombinants.  相似文献   
109.
110.
BACKGROUND: Although 15(S)-hydroxyeicosatetraenoic acid (15(S)-HETE), a product of 15-lipoxygenase (15-LO), may be involved in mild to moderate asthma, little is known about its potential roles in severe asthma. OBJECTIVES: This study was performed to evaluate 15(S)-HETE levels in bronchoalveolar lavage fluid (BALF) from severe asthmatics with and without airway eosinophils and from the control groups. In addition, 15-LO protein expression was examined in endobronchial biopsy, while its expression and activation were evaluated in BAL cells. RESULTS: While 15(S)-HETE levels in BALF were significantly higher in all severe asthmatics than normal subjects, severe asthmatics with airway eosinophils had the highest levels compared with mild, moderate asthmatics and normal subjects. 15(S)-HETE levels were associated with tissue eosinophil numbers, sub-basement membrane thickness and BALF tissue inhibitor of metalloproteinase-1 levels, and were accompanied by increased 15-LO expression in bronchial epithelium. In addition, activation of 15-LO was suggested by the increased proportion of 15-LO in the cytoplasmic membrane of alveolar macrophages from severe asthmatics. CONCLUSION: The data suggest that severe asthmatics with persistent airway eosinophils manifest high levels of 15(S)-HETE in BALF, which may be associated with airway fibrosis. It is likely that 15-LO expression and activation by airway cells explain the increased 15(S)-HETE levels.  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