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   3506770篇
  免费   285758篇
  国内免费   13476篇
耳鼻咽喉   47678篇
儿科学   110913篇
妇产科学   90782篇
基础医学   555804篇
口腔科学   94483篇
临床医学   320010篇
内科学   620124篇
皮肤病学   92162篇
神经病学   299555篇
特种医学   136639篇
外国民族医学   289篇
外科学   534723篇
综合类   103517篇
现状与发展   24篇
一般理论   2488篇
预防医学   301043篇
眼科学   79745篇
药学   240163篇
  28篇
中国医学   9448篇
肿瘤学   166386篇
  2021年   55405篇
  2020年   35288篇
  2019年   58297篇
  2018年   71935篇
  2017年   54847篇
  2016年   60323篇
  2015年   74366篇
  2014年   108591篇
  2013年   174057篇
  2012年   99527篇
  2011年   100997篇
  2010年   118675篇
  2009年   122351篇
  2008年   87525篇
  2007年   91716篇
  2006年   101075篇
  2005年   96932篇
  2004年   98344篇
  2003年   88824篇
  2002年   78539篇
  2001年   103053篇
  2000年   95715篇
  1999年   95703篇
  1998年   64848篇
  1997年   62799篇
  1996年   60954篇
  1995年   56339篇
  1994年   50600篇
  1993年   47254篇
  1992年   67902篇
  1991年   65152篇
  1990年   61812篇
  1989年   60913篇
  1988年   56734篇
  1987年   55519篇
  1986年   52913篇
  1985年   52524篇
  1984年   48405篇
  1983年   44531篇
  1982年   41857篇
  1981年   39575篇
  1980年   37274篇
  1979年   40917篇
  1978年   36415篇
  1977年   32977篇
  1976年   30240篇
  1975年   29140篇
  1974年   30673篇
  1973年   29778篇
  1972年   28013篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
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   
993.
994.
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   
995.
Vibrio cholerae was isolated from the blood cultures of a neutropenic patient treated with chemotherapy for non-small-cell lung cancer. Attempts to isolate Vibrio spp. from a rectal swab and stool were unsuccessful. Piperacillin/tazobactam treatment resulted in eradication of the microorganism from the patient's blood. Although Vibrio spp. have occasionally been the source of infection in immunocompromised patients, this report describes the first case of non-0:1 Vibrio cholerae bacteremia in a neutropenic patient with a solid tumour. Electronic Publication  相似文献   
996.
The in vitro activities of povidone iodine, potassium peroxymonosulfate, and dimethyldidecylammonium chloride were investigated against 379 nosocomial isolates of Staphylococcus aureus and Pseudomonas aeruginosa responsible for surgical wound infections in patients operated on between July 1995 and June 2001. Overall, the isolates were inhibited by the antiseptics at concentrations below those used routinely. In spite of increasing resistance to the various antibiotics used to treat surgical wound infections, no significant variation in the susceptibility to antiseptics was demonstrated during this 6-year study. Electronic Publication  相似文献   
997.
998.
We have measured the release of adenosine and inosine from the dorsal surface of the brainstem and from within the nucleus tractus solitarii (NTS) during the defence response evoked by hypothalamic stimulation in the anaesthetised rat. At the surface of the brainstem, only release of inosine was detected on hypothalamic defence area stimulation. This inosine signal was greatly reduced by addition of the ecto-5'-nucleotidase inhibitor α,β-methylene ADP (200 μM), suggesting that the inosine arose from adenosine that was produced in the extracellular space by the prior release of ATP. By placing a microelectrode biosensor into the NTS under stereotaxic control we have recorded release of adenosine within this nucleus. By contrast to the brainstem surface, a fast increase in adenosine, accompanied only by a much smaller change in inosine levels, was seen following stimulation of the hypothalamic defence area. The release of adenosine following hypothalamic stimulation was mainly confined to a narrow region of the NTS some 500 μm in length around the level of the obex. Interestingly the release of adenosine was depletable: when the defence reaction was evoked at short time intervals, much less adenosine was released on the second stimulus. Our novel techniques have given unprecedented real-time measurement and localisation of adenosine release in vivo and demonstrate that adenosine is released at the right time and in sufficient quantities to contribute to the cardiovascular components of the defence reaction.  相似文献   
999.
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   
1000.
Can quality of life be quantified?   总被引:1,自引:0,他引:1  
  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