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   1472254篇
  免费   101677篇
  国内免费   2340篇
耳鼻咽喉   20746篇
儿科学   48293篇
妇产科学   41735篇
基础医学   214984篇
口腔科学   40057篇
临床医学   123768篇
内科学   293963篇
皮肤病学   31742篇
神经病学   116939篇
特种医学   55840篇
外国民族医学   457篇
外科学   221653篇
综合类   27326篇
现状与发展   1篇
一般理论   358篇
预防医学   110532篇
眼科学   33037篇
药学   111519篇
  1篇
中国医学   3086篇
肿瘤学   80234篇
  2019年   11425篇
  2018年   18315篇
  2017年   13190篇
  2016年   14315篇
  2015年   16350篇
  2014年   20921篇
  2013年   32308篇
  2012年   47551篇
  2011年   49865篇
  2010年   28100篇
  2009年   25115篇
  2008年   46902篇
  2007年   50697篇
  2006年   50162篇
  2005年   49328篇
  2004年   47088篇
  2003年   45158篇
  2002年   44127篇
  2001年   62581篇
  2000年   64142篇
  1999年   54704篇
  1998年   14938篇
  1997年   13404篇
  1996年   13608篇
  1995年   12850篇
  1994年   12201篇
  1992年   43329篇
  1991年   42463篇
  1990年   41917篇
  1989年   40529篇
  1988年   37816篇
  1987年   36900篇
  1986年   35181篇
  1985年   33484篇
  1984年   24917篇
  1983年   21674篇
  1982年   12896篇
  1981年   11342篇
  1979年   23532篇
  1978年   16489篇
  1977年   14293篇
  1976年   13462篇
  1975年   14807篇
  1974年   17412篇
  1973年   16837篇
  1972年   16004篇
  1971年   14921篇
  1970年   13876篇
  1969年   13421篇
  1968年   12566篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
981.
This is a review of 4.690 necropsies and 24.209 surgical pathology specimens describing the association between megacolon chagasic and malignant tumors of the large bowel. The prevalence of malignant tumors of the large bowel was not higher in megacolon.  相似文献   
982.
Enoximone is a positive inotropic agent belonging to the group of phosphodiesterase F-III inhibitors. The drug was tested in 34 patients uncontrolled by sympathomimetic drugs and referred to our department for urgent heart transplantation or circulatory assistance. After insertion of a Swan-Ganzgatheter and a radial artery catheter for haemodynamic monitoring, enoximone was administered as a 15-minute intravenous bolus injection of 1 to 2.5 mg/kf every 8 hours, in addition to sympathomimetic agents. Clinical and haemodynamic improvement was observed after thirty minutes in 30 patients. The cardiac index rose from 1.82 to 2.67 l/min/m2 and the pulmonary wedge pressure fell from 30.8 to 18.9 mmHg. Systemic arterial resistance decreased from 2170 to 1520 dyn. s. cm-5, and pulmonary resistance from 5.5 to 4.6 Wood units (p less than 0.01 for all values). Four patients had no haemodynamic improvement and were put on circulatory assistance, using a Jarvik 7 total artificial heart in 3 of them and heterotopic circulatory assistance in one. After clinical investigation for contra-indication to heart transplantation, and as their improved haemodynamic status permitted, 12 of the 30 patients were considered suitable (group B) for heart transplantation. Transplantation was performed within a week of admission in 11 patients without any need for mechanical assistance. One of the group B patients who required implantation of a Jarvik 7 artificial heart died after 12 hours of assistance. Eighteen patients were considered unsuitable for transplantation (group A) and treated medically.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
983.
In a study of rock music preferences, listening/watching behavior, and views on destructive rock lyrics, 894 adolescents in grades 9 through 12 in rural, urban, suburban public, and metropolitan parochial schools were administered a questionnaire. Demographic information on parents was also collected. It was found that 17.5% of the students were fans of rock music with lyrics that promote homicide, suicide, or satanic practices (HSSR). Loglinear and multiple regression analyses were used to analyze the data. Parents' marital status, student sex, race, and school environment (urban, rural, suburban, etc.) were found to be significant predictors of HSSR status. As compared with non-HSSR fans, the HSSR fans were more likely to have parents who were “Never married” or “Remarried” and less likely to have parents in the “married” category. The HSSR fans were more likely to be male, white, and enrolled in urban schools but not parochial schools than expected; HSSR status also significantly predicted other music-related attitudes and behaviors. The HSSR fans reported liking both the sound and the lyrics of rock music more often than did non-HSSR fans, as did females and urban students. The HSSR fans more often felt that children under 10 years of age should be allowed to listen to HSSR lyrics, and they more frequently expressed the conviction that HSSR music does not affect adolescents' homicidal or self-destructive behavior. The HSSR fans and females reported more nearly complete knowledge of lyrics than did non-HSSR fans and males. The HSSR fans reported that they watch more MTV than did any other group except rural students.  相似文献   
984.
This study determined nursing research priorities and focused on the development of a nursing research program within a single institution. Of the 715 nurses within the Department of Nursing, 286 (40%) responded to the first round of a two-round Delphi technique, and 137 (48%) responded to the second. The following clinical priorities were determined: prevention and treatment of pressure sores, pain management, treatment of nosocomial infections, and patient education. Nonclinical priorities included staffing and its effects on turnover and patient care, job satisfaction, and factors influencing the quality of nursing care. Serendipitous findings underscored the relevance of the Department of Nursing's conceptual framework to nursing practice and research, revealed the need for dissemination of current research results, and suggested that nurses want to participate in research without assuming responsibility beyond their expertise.  相似文献   
985.
We present a case report of a patient suffering from portal and superior mesenteric vein thrombosis secondary to splenectomy. No surgical procedure could be performed due to the extension of thrombus.Local fibrinolysis treatment with urokinase through a percutaneous transhepatic approach was decided upon, and this procedure had a successful patient outcome.  相似文献   
986.
987.
G Rao  H R Madoff 《Chest》1989,95(1):244-245
A 64-year-old woman presented in shock. The computed tomography (CT) scan confirmed rupture of the left diaphragm with strangulation. Three days after surgery, the patient developed herniation of abdominal contents on the right side with cardiorespiratory collapse. Marlex mesh was used to repair on the right side. Postoperatively, she needed partial gastrectomy for massive duodenal ulcer bleeding. A dual chamber pacemaker was used to correct the complete heart block.  相似文献   
988.
S M Donovan  Y Oh  H Pham  R G Rosenfeld 《Endocrinology》1989,125(5):2621-2627
Insulin-like growth factors (IGF-I and -II) are peptide growth factors that may be important for neonatal development. Specific high affinity IGF binding proteins (BPs) have been characterized in serum and extracellular fluids. The major serum binding complex in the adult has an apparent Mr of 150 K, while the predominant BP in the neonate is approximately 30 K. In the rat, the transition from the neonatal BP to the adult form occurs during the third postnatal week, concomitant with an increase in serum IGF-I and a decrease in serum IGF-II concentrations. Using specific RIAs and Western ligand blot analyses we have characterized the changes in serum IGF and IGF BPs, respectively, during the early postnatal period. Seven BPs were identified in serum with apparent Mr values of 42, 41, 40, 38, 28, 26, and 22 K. After deglycosylation, the 42, 41, 40, and 38 K BPs were reduced to two bands with apparent Mr values of 35 and 32 K, while the 28, 26, and 22 K BP were unchanged. In the neonate, the 28, 26, and 22 K BPs were present, with the 28 K BP in highest concentration. With increasing age, the 28 K BP decreased and the 42, 41, 40, and 38 K BPs appeared at approximately 19 days of age. Comparison of Western ligand blots of neonatal serum, BRL-3A conditioned media, rat amniotic fluid, and rat cerebrospinal fluid (CSF) demonstrated that all contained a prominent 28 K BP. A polyclonal antibody (alpha Hec 1) developed against the 31 K human IGF-BP (hBP-31) immunoprecipitated the 28 K BP from neonatal rat serum, BRL-3A media, rat amniotic fluid, and rat CSF, but did not react with adult rat serum. These findings suggest that, in the rat, the predominant neonatal serum BP is structurally and immunologically similar to the major BRL-3A, amniotic fluid, and CSF BPs, but distinct from the predominant adult serum BP.  相似文献   
989.
Elevated serum levels of keratan sulfate (KS) and hyaluronate (HA) in patients with osteoarthritis (OA) have been reported. We measured KS and HA in dogs to determine if there was an elevation of these serum glycosaminoglycans in a canine model of OA. A single intraarticular injection of 1 mg of chymopapain into a shoulder joint increased serum KS by tenfold, and HA by less than twofold, in 24 hours. Serum KS and HA levels were 3-5-fold higher in dogs younger than 2 months of age than in older dogs. Serum KS and HA concentrations and synovial fluid KS concentrations were unrelated to spontaneous cartilage degeneration in 1-year-old dogs. Higher KS levels in synovial fluid correlated with higher KS levels in serum (r = 0.54, P less than 0.025). The mean KS concentration in sera of older dogs (greater than 3 years old) with OA was 37% higher than that in disease-free controls, but the difference between the groups was not statistically significant. Thus, elevated levels of serum KS and HA do not appear to have clinical significance in this model of OA.  相似文献   
990.
Natural history of aortoarteritis (Takayasu's disease)   总被引:8,自引:0,他引:8  
The natural history of aortoarteritis was studied in 88 patients (54 women and 34 men). The average age was 24.0 +/- 8.8 years at onset of symptoms and 28.3 +/- 9.9 years at diagnosis. The follow-up period was 83.6 +/- 74.4 months from onset and 33.2 +/- 37.0 months from diagnosis. Ten patients (11.4%) died during follow-up (0.016 deaths/patient year), and 22 patients (25%) suffered major nonfatal events (0.042 events/patient year). The cumulative survival at 5 and 10 years after the onset was 91.0 +/- 3.3% and 84.0 +/- 5.6% (mean +/- SEM), respectively. The event-free survival rates at the same intervals after onset were 74.9 +/- 5.0% and 64.0 +/- 7.4%, respectively. The overall survival and event-free survival at 10 years after diagnosis was 80.3 +/- 6.5% and 61.6 +/- 7.5%, respectively. Patients with no complications or a mild single complication at diagnosis had a higher event-free survival rate than those with severe single complication or multiple complications at 5 years--97.0 +/- 2.9% and 59.7 +/- 7.3%, respectively (p less than 0.001). Severe hypertension (p less than 0.01), severe functional disability (p less than 0.01), and evidence of cardiac involvement (p less than 0.05) were good predictors of either death or major event on follow-up. These data are useful in making an objective assessment of the prognosis and in planning elective interventions.  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