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   3303589篇
  免费   272203篇
  国内免费   7189篇
耳鼻咽喉   49214篇
儿科学   104470篇
妇产科学   88146篇
基础医学   459922篇
口腔科学   93044篇
临床医学   316200篇
内科学   651838篇
皮肤病学   72457篇
神经病学   276493篇
特种医学   129334篇
外国民族医学   1104篇
外科学   502321篇
综合类   73962篇
现状与发展   75篇
一般理论   1435篇
预防医学   267243篇
眼科学   77801篇
药学   238188篇
  11篇
中国医学   5748篇
肿瘤学   173975篇
  2018年   38466篇
  2017年   30930篇
  2016年   34182篇
  2015年   38059篇
  2014年   57219篇
  2013年   80999篇
  2012年   97271篇
  2011年   103037篇
  2010年   65998篇
  2009年   66598篇
  2008年   98241篇
  2007年   103169篇
  2006年   105461篇
  2005年   100933篇
  2004年   96599篇
  2003年   92437篇
  2002年   90946篇
  2001年   145892篇
  2000年   149823篇
  1999年   127336篇
  1998年   39214篇
  1997年   35602篇
  1996年   35478篇
  1995年   33981篇
  1994年   31177篇
  1993年   28966篇
  1992年   101890篇
  1991年   99150篇
  1990年   95663篇
  1989年   92402篇
  1988年   85892篇
  1987年   84335篇
  1986年   80208篇
  1985年   76400篇
  1984年   58042篇
  1983年   50140篇
  1982年   30464篇
  1981年   27274篇
  1979年   54818篇
  1978年   39192篇
  1977年   33088篇
  1976年   30859篇
  1975年   32834篇
  1974年   40229篇
  1973年   38690篇
  1972年   36555篇
  1971年   33847篇
  1970年   31879篇
  1969年   29717篇
  1968年   27230篇
排序方式: 共有10000条查询结果,搜索用时 21 毫秒
991.
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   
992.
993.
To determine whether well-appearing children found incidentally to be neutropenic are at risk for an infectious complication, 44 consecutive months of hematology laboratory records were reviewed. One hundred nineteen patients had medical record documentation regarding clinical course, serial white blood cell counts, and the absence of serious infections, chronic illnesses, or a family history known to be associated with neutropenia. The median duration of documented neutropenia was 13 days (range, 1 to 491 days). Infectious complications occurred in 4 of the 36 patients who had neutropenia for more than 30 days (2 with stomatitis, 1 with cellulitis, and 1 with pneumonia) but in none with shorter durations of neutropenia. There were no significant associations between the development of an infectious complication and either the initial absolute neutrophil count or the lowest documented absolute neutrophil count, nor was there a correlation between the initial absolute neutrophil count and the duration of neutropenia. These data indicate that infectious complications occur in otherwise well children with unexplained neutropenia that persists, but these infections are infrequent and usually are superficial.  相似文献   
994.
Usher syndrome: clinical findings and gene localization studies   总被引:3,自引:0,他引:3  
The issue of genetic heterogeneity is a critical problem in the localization of the gene(s) for Usher syndrome. Based on the data obtained on families studied to date, the differences between type I and type II Usher syndrome appear quite distinct with regard to auditory and vestibular function. Although the majority of families can be confidently diagnosed as typical type I or type II, clinical investigations revealed four families with findings that did not fit into either of the two more common subtypes. These findings emphasize the critical importance of an in-depth clinical analysis concomitant with the linkage investigation to assure accurate subtyping of Usher syndrome. Based on an analysis of only those families with definite type I or type II Usher syndrome, approximately 17% of the genome can be excluded as a potential site of the gene for type I, and 14% can be excluded as the site for the type II gene. This study will continue until the Usher gene(s) is successfully localized.  相似文献   
995.
This paper reports the results of an experimental study modeled after a study conducted by Kaplan et al. The hypothesis tested was: Adolescents who receive a social learning intervention (SLI) will show greater improvement in metabolic control of their diabetes than will adolescents who receive only traditional diabetes instruction. Thirty-four adolescents between the ages of 12 and 16 who attended a midwestern camp were randomly divided into two groups. Both groups attended a daily 1-hour teaching session about diabetes. Later each day, the experimental group received an SLI consisting of role modeling to help the subjects circumvent peer pressure. To determine metabolic control, HbA1 values were determined before and 3 1/2 months after the intervention. The control group showed no significant difference in HbA1 values, while the experimental group showed a decrease in metabolic control.  相似文献   
996.
D R Holmes  R E Vlietstra 《JAMA》1989,261(14):2109-2115
Percutaneous transluminal coronary angioplasty has grown exponentially since its introduction. Currently, selection criteria include single-vessel and multivessel disease, stable and unstable angina, and acute infarction. The outcome depends on specific patient and angiographic characteristics. In ideal lesions, success rates should be greater than 90%, with low morbidity and mortality. With more severe and diffuse multivessel disease, success rates are lower and complication rates are higher. In these cases, percutaneous transluminal coronary angioplasty still offers a reasonable option, provided complete revascularization can be achieved or the angina-producing lesion dilated. Numerous issues remain unresolved, including (1) the role of percutaneous transluminal coronary angioplasty vs coronary surgery (currently being tested), (2) restenosis, which occurs in approximately 30% of treated lesions, and (3) organizational adjustments such as training and certification to maintain high standards of care.  相似文献   
997.
998.
Gram negative endotoxins play a contributory role in the syndrome which results from over consumption of carbohydrates by horses and ponies. Since the antibiotic polymyxin B exerts a direct anti-endotoxin effect by chemically modifying the active lipid A moiety of endotoxin, it might be expected to protect horses after carbohydrate overload and provide a new therapeutic and experimental tool for this condition. The present study was undertaken to evaluate the effect of polymyxin B on hemostatic, hemodynamic, acid-base, and clinical aspects of the syndrome resulting from carbohydrate overload. Experimentally-induced carbohydrate overload resulted in lactic acidosis, hypercoagulability, hypovolemic shock and lameness. Although there was a slight delay in the onset of clinical signs resulting from experimental carbohydrate overload in treated animals, polymyxin B administered iv at 2.5 mg/kg every 6 hr failed to significantly ameliorate the coagulopathy, acidosis, lameness and shock induced by alimentary carbohydrate overload.  相似文献   
999.
The authors studied the clinical features and outcome at 6 months in 191 patients with subarachnoid hemorrhage (SAH) from ruptured aneurysms. Aneurysm repair (AR) was undertaken in 123 cases (64.4%). In the non-AR group (n = 68), 48.5% of the patients were 70 years of age or older, compared with 12.2% in the AR group. The duration from onset to admission was less than 3 hours in 48 non-AR cases (70.6%) and in 42 AR cases (34.1%). Among non-AR patients, 63.2% were Hunt and Hess grade IV or V, whereas the figure for AR patients was only 14.7%. By 6 months after SAH, 94.1% of non-AR patients had died, and the remainder were vegetative or severely disabled. In contrast, only 15.4% in the AR group died, and over 50% showed good recovery. The large majority of non-AR patients were treated conservatively because they were judged to be poor surgical risks and, among these patients, nearly one half were elderly. In the 10 elderly patients considered good surgical candidates, vasospasm was the most common reason (70%) for not performing AR.  相似文献   
1000.
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