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   34230篇
  免费   2832篇
  国内免费   114篇
耳鼻咽喉   340篇
儿科学   984篇
妇产科学   640篇
基础医学   4770篇
口腔科学   469篇
临床医学   3726篇
内科学   7017篇
皮肤病学   421篇
神经病学   3127篇
特种医学   1083篇
外科学   5578篇
综合类   557篇
现状与发展   1篇
一般理论   33篇
预防医学   2845篇
眼科学   645篇
药学   2359篇
中国医学   65篇
肿瘤学   2516篇
  2023年   286篇
  2022年   502篇
  2021年   1125篇
  2020年   578篇
  2019年   938篇
  2018年   1090篇
  2017年   753篇
  2016年   763篇
  2015年   882篇
  2014年   1208篇
  2013年   1550篇
  2012年   2436篇
  2011年   2466篇
  2010年   1328篇
  2009年   1147篇
  2008年   1928篇
  2007年   1968篇
  2006年   1826篇
  2005年   1787篇
  2004年   1673篇
  2003年   1569篇
  2002年   1539篇
  2001年   437篇
  2000年   438篇
  1999年   467篇
  1998年   343篇
  1997年   295篇
  1996年   260篇
  1995年   255篇
  1994年   246篇
  1993年   197篇
  1992年   328篇
  1991年   285篇
  1990年   296篇
  1989年   270篇
  1988年   254篇
  1987年   267篇
  1986年   226篇
  1985年   223篇
  1984年   203篇
  1983年   182篇
  1982年   157篇
  1981年   164篇
  1980年   161篇
  1979年   182篇
  1978年   135篇
  1977年   117篇
  1974年   115篇
  1973年   134篇
  1971年   114篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Five patients showing clinical signs resembling the 'toxic shock syndrome' presented over a 4-month period at the Wessex Regional Burns Centre. Toxin-producing isolates of Staphylococcus aureus were made from wound swabs in four of the five patients. Four different phage types producing four different toxins were observed. Seven other patients yielded staphylococci from wound swabs but did not develop the toxic shock syndrome. In three of these latter patients the staphylococcus isolated was toxin producing. Since the syndrome carries a significant mortality risk it is desirable that it is recognized and treated without delay. To this end a simplified set of criteria for the identification of probable toxic shock syndrome cases is proposed. The observations suggest that toxic shock syndrome is more common than previously supposed. The syndrome may show a broad spectrum in its clinical presentation, and involve a wide range of staphylococcal phage types with possible involvement of several different enterotoxins.  相似文献   
72.
Canadian Journal of Anesthesia/Journal canadien d'anesthésie - Today’s anaesthesia journals are faced with problems in the quality of materials being published. The stature of...  相似文献   
73.
74.
Following the toxicity and synthetic difficulties encountered with the hypoxic cell radiosensitizer RSU 1069, efforts have focused on development of a superior analogue. Two compounds, RB 6145 and PD 130908, have emerged from this program which overcome the instability and synthetic problems associated with RSU 1069 while retaining favorable biological activity. Both agents show comparable radiosensitizing activity to RSU 1069 following oral or i.p. administration to mice bearing the KHT or RIF-1 tumors. Sensitizing efficiency is about 10 X greater than that observed for misonidazole or etanidazole. Toxicity toward hypoxic tumor cells in vivo is demonstrated by clamping tumors (for 60 min) following administration of PD 130908 or RB 6145. Both are effective hypoxic cytotoxins, but less potent than RSU 1069. Systemic toxicity is substantially reduced following oral drug administration. Further, doses achievable following fractionated drug treatments are sufficiently high to produce significant levels of radiosensitization.  相似文献   
75.
Forty-three patients were prospectively studied following tracheo-oesophageal puncture at the time of laryngectomy (primary voice restoration). Blom-Singer voice prostheses were used. The surgery was regarded as successful if a patient continued to use the voice prosthesis as the major means of communication with clear intelligibility 4 months after the operation. Using this criterion, the success in this series was 70%. No attempt was made to assess the quality of speech. Complications and causes of failure are discussed.  相似文献   
76.
77.
OBJECTIVES: To determine analytically the amount of potassium in raw tuberous root vegetables (TRV); to estimate the amount of potassium that can be leached from raw TRV by soaking in water; and to determine whether the duration of soaking and the cooking method selected affect potassium extraction. DESIGN: Fresh TRV (ie, fresh and sweet batata, cocomalanga, dasheen, eddo, black yam, white yam, yellow yam, yampi, malanga, red yautia, white yautia, and yuca) were obtained from an ethnic market. Five experimental conditions with variations in soak time and cooking method were applied. Potassium was extracted from the ash of dried samples. The potassium content of aqueous extractions was determined through atomic absorption spectrophotometry. RESULTS: Mean potassium content was highest in raw cocomalanga and lowest in raw dasheen. All of the raw TRV, except for dasheen, had a potassium content >200 mg (5.1 mEq)/100 g sample. Soaking was not effective in the leaching of significant amounts of potassium from most TRV. The double cooking (DC) method (ie, boil, rinse, boil again) leached more potassium from most TRV than did the normal cooking (NC) method (ie, boil), except with dasheen and yellow yam. More vegetables retained a potassium content >200 mg (5.1 mEq)/100 g following NC versus DC (92% versus 54%). CONCLUSIONS: The potassium content of raw TRV varied considerably, with most tubers retaining a moderate or high potassium content following the leaching procedures. However, this study showed that DC appears to be more effective than NC for leaching potassium from TRV.  相似文献   
78.
We studied hypertrophic patterns in the electrocardiograms of 60 Nigerian hypertensives. Thirty were in heart failure and 30 without failure (matched for age and sex). Combined left ventricular and left atrial hypertrophy was the commonest finding occurring in 58.3%, followed by left ventricular hypertrophy alone in 30%. 76.7% and 40% had combined left ventricular and left atrial hypertrophy in the heart failure and the non-heart failure groups, respectively (P less than 0.02). Though these changes increased with increased blood pressure, the latter is similarly severe in both groups. 100% of patients in Class IV failure had combined left ventricular and left atrial hypertrophy. The 3 patients who had additional right atrial hypertrophy were in Class IV failure, 2 of whom died during follow-up. These changes are much more marked at presentation than reprots in caucasians and even in previous reports in Africans. The changes reflect the long-standing nature and severity of the hypertensive process, and point to the fact that the majority of hypertensives in this environment present rather late.  相似文献   
79.
80.
Extrinsic denervation may be responsible for motor dysfunction after small bowel transplantation. The aim of this study was to examine the role of extrinsic innervation of canine jejunum on contractile activity. An in vitro dose response of cholinergic and adrenergic agonists was evaluated in canine jejunal strips of circular muscle at 0, 2, and 8 weeks in a control group and after jejunoileal extrinsic denervation (EX DEN). Neurons in circular muscle were quantitated by means of immunohistochemical techniques. Adrenergic and cholinergic responses did not differ at any time in the control group. However, at 2 and 8 weeks, extrinsic denervation caused an increased sensitivity to the procontractile effects of the cholinergic agonist bethanechol at the level of the smooth muscle cells, and increased sensitivity to the inhibitory effects of the adrenergic agent norepinephrine mediated at the level of the enteric nervous system. Immunohistochemical analysis showed a reduction in all neurons and a complete lack of adrenergic fibers in the EX DEN group after 2 and 8 weeks. Extrinsic denervation induces enteric neuronal cholinergic and adrenergic smooth muscle hypersensitivity in canine jejunal circular muscle. Presented in part at the annual meeting of the American Gastroenterological Association, Orlando, Florida, May 18, 1999 (poster presentation), and published as an abstract in Gastroenterology 116:A1075, 1999. Supported by United States Public Health Service grant DK39337 from the National Institutes of Health (M.G.S.); the Swiss National Science Foundation; the Swiss Society of Gastroenterology and Hepatology; the Swiss Foundation for Medical and Biological Science; the Novartis Foundation; Astra Zeneca Pharmaceuticals, Switzerland; and the Department of Visceral and Transplantation Surgery, University of Bern, Switzerland.  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