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   1198441篇
  免费   86639篇
  国内免费   3043篇
耳鼻咽喉   15627篇
儿科学   40553篇
妇产科学   32545篇
基础医学   174113篇
口腔科学   32537篇
临床医学   106554篇
内科学   238146篇
皮肤病学   28174篇
神经病学   97257篇
特种医学   44690篇
外国民族医学   385篇
外科学   174863篇
综合类   24632篇
一般理论   444篇
预防医学   96452篇
眼科学   26614篇
药学   86006篇
  3篇
中国医学   2646篇
肿瘤学   65882篇
  2021年   9967篇
  2019年   10774篇
  2018年   17174篇
  2017年   12557篇
  2016年   13689篇
  2015年   15431篇
  2014年   19432篇
  2013年   30123篇
  2012年   43201篇
  2011年   45091篇
  2010年   25561篇
  2009年   22710篇
  2008年   41080篇
  2007年   43627篇
  2006年   43031篇
  2005年   41587篇
  2004年   40043篇
  2003年   37994篇
  2002年   36397篇
  2001年   51635篇
  2000年   52873篇
  1999年   44525篇
  1998年   11976篇
  1997年   10757篇
  1996年   10804篇
  1995年   10362篇
  1994年   9617篇
  1993年   8961篇
  1992年   34743篇
  1991年   33695篇
  1990年   33142篇
  1989年   31824篇
  1988年   29066篇
  1987年   29069篇
  1986年   27151篇
  1985年   26140篇
  1984年   19508篇
  1983年   16453篇
  1982年   9846篇
  1979年   17848篇
  1978年   12913篇
  1977年   10971篇
  1976年   10293篇
  1975年   10836篇
  1974年   13150篇
  1973年   12678篇
  1972年   11658篇
  1971年   10884篇
  1970年   10121篇
  1969年   9507篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
After ingesting or inhaling laundry detergent powder, eight children required hospital admission. The predominant symptoms were stridor, drooling, and respiratory distress. All but one patient underwent endoscopy of the airways and the esophagus, five children were admitted to the intensive care unit, and four children required endotracheal intubation. Laundry detergent ingestions are generally considered to have minor consequences, and there exists a paucity of literature on the subject. Evidence of significant morbidity incurred because of ingestion or inhalation of sodium carbonate-containing laundry detergent powder is presented, together with a review of the existing literature.  相似文献   
992.
993.
Tumor material from 91 patients with squamous cell carcinoma of the head and neck was transplanted subcutaneously in athymic nude mice. In the first (man to mouse) passage, the calculated mean probability of tumor take in a single mouse was 11%. The probability of growth in the first passage was significantly better for moderately and poorly differentiated tumors than for well-differentiated tumors. Also, the implantation of lymph node material resulted in a significantly better tumor take rate than material taken from a primary tumor. Transplantability was not dependent on the following characteristics: localization, T or N stage of the tumor, or the sex of the patients. Once growth was established, all variables studied had no influence on the probability of growth in the subsequent mouse passages. A relationship between tumor growth in nude mice and patient prognosis could not be found. When transplanting head and neck squamous cell carcinoma in nude mice, it has to be recognized that some tumor characteristics will influence the success of tumor growth.  相似文献   
994.
Unintelligible speech in childhood is often characterised by the use of unusual or deviant (i.e. non-developmental) phonological processes, e.g. initial consonant deletion. These processes are reported to appear at speech onset and to undergo little spontaneous change during the preschool years. The study reported here documents the changes that occurred in the phonological systems of seven phonologically disordered children during remediation that targeted unusual phonological processes. Qualitative changes in phonological process use were observed for all children. Six of the children made quantitative improvement in terms of the percentage consonants produced correctly in spontaneous speech. Individual differences in phonological learning strategy use are described.  相似文献   
995.
Dietary factors in the risk of bladder cancer   总被引:2,自引:0,他引:2  
The relationship between selected dietary factors and the risk of bladder cancer was investigated in a case-control study conducted in northern Italy. The study included 163 cases and 181 controls who were hospitalized for acute, nonneoplastic or urinary tract diseases. The frequency of consumption of green vegetables and carrots was lower in the cases; thus, the estimated relative risks for the upper vs. the lower tertiles were 0.6 for green vegetables and 0.5 for carrots. Significant inverse trends in risk emerged with estimated carotenoid (as well as retinoid) intake. The apparent protection conveyed by vitamin A was stronger in current smokers. The risk of bladder cancer was not related to scores of fat and measures of alcohol consumption; the risk was elevated in coffee drinkers (although there was no tendency to rise with higher consumption), but it was reduced in tea drinkers. These findings were not explainable in terms of selection, information, or confounding bias. Thus, although available information is too uncertain for any precise definition of specific (micro)nutrients related to bladder cancer risk, the confirmation that several aspects of a less-affluent diet adversely affect the risk is still of interest in terms of a better understanding of bladder carcinogenesis.  相似文献   
996.
A case of tumoral calcinosis simulating osteomyelitis and associated with bunion formation in a 20-year-old female is presented. The most striking findings in this patient were the soft tissue calcifications. There was no evidence of any of the known causes of heterotopic calcifications. This kind of simulation between tumoral calcinosis bunion formation and osteomyelitis has not been previously described.  相似文献   
997.
998.
A topical formulation of ketoprofen, a widely used nonsteroidal antiinflammatory drug, has recently been developed. Ten healthy young subjects (mean age 23.5 +/- 2.5 years) received daily 15 g of 2.5% ketoprofen gel, corresponding to 375 mg on the skin of the back over an area of 750 cm2. Plasma samples were collected after the first dose and after 10 days of chronic treatment. Urine was also collected. Ketoprofen was assayed by HPLC. The peak plasma concentration was 144 +/- 91 ng/ml after the first administration with apparent absorption and elimination half-lives of 3.2 +/- 2.4 h and 27.7 +/- 18.0 h, respectively. The total quantities of ketoprofen eliminated in the urine represented about 2.6% of the first dose applied. At the end of the study, the apparent half-life of unchanged ketoprofen was 17.1 +/- 9.1 h, and there was no accumulation. In this study, no sign of local intolerance was seen.  相似文献   
999.
This study demonstrated the existence of specific binding sites for [3H]Ro 19-6327 in human platelet membranes. This compound is a novel, time-dependent inhibitor of monoamine oxidase type B (MAO-B) and is structurally closely related to [3H]Ro 16-6491. The density of the sites labelled with high affinity by [3H]Ro 19-6327 was similar to that observed in previous studies with [3H]Ro 16-6491 as ligand. Binding was reversible at 20 degrees C and showed a relatively slow dissociation (t1/2 = 220 min). The dissociation rate was markedly decreased (t1/2 = greater than 24h) at 0 degrees C. MAO-B, but not MAO-A inhibitors, effectively prevented the binding of [3H]Ro 19-6327. Like [3H]Ro 16-6491, [3H]Ro 19-6327 is recognized as a substrate by MAO-B, being eventually deaminated by the enzyme. Since the deaminated aldehyde derivative of Ro 19-6327 did not inhibit MAO-B, a still unidentified reversible adduct, formed at the MAO-B active site, might explain the high potency and selectivity of [3H]Ro 19-6327. Incubation of the radioligand-enzyme complex from platelet and brain membranes with NaBH3CN and acetic acid (to pH 4.5) caused the irreversible incorporation of the radioactivity into a single polypeptide as shown by SDS-PAGE analysis. This polypeptide had a molecular weight identical to that of the MAO-B subunit, i.e. 58,000. The presence of unlabelled MAO-B inhibitors in the incubation mixture prevented the covalent incorporation of [3H]Ro 19-6327. The irreversible MAO-B inhibitor, [3H] pargyline, labelled a protein with a molecular weight identical to the protein labelled by [3H]Ro 19-6327.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
1000.
Herniation of a thoracic disc in an acromegalic giant is reported. Degenerative changes in the spine in association with dorsal kyphosis, and the additional strain, resulted in the disc prolapse.  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