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   15874篇
  免费   1226篇
  国内免费   298篇
耳鼻咽喉   184篇
儿科学   382篇
妇产科学   514篇
基础医学   1856篇
口腔科学   784篇
临床医学   1503篇
内科学   3188篇
皮肤病学   185篇
神经病学   1516篇
特种医学   700篇
外科学   2024篇
综合类   999篇
一般理论   1篇
预防医学   1047篇
眼科学   434篇
药学   1067篇
  4篇
中国医学   182篇
肿瘤学   828篇
  2023年   130篇
  2022年   216篇
  2021年   348篇
  2020年   247篇
  2019年   260篇
  2018年   317篇
  2017年   337篇
  2016年   326篇
  2015年   434篇
  2014年   473篇
  2013年   641篇
  2012年   714篇
  2011年   866篇
  2010年   678篇
  2009年   622篇
  2008年   734篇
  2007年   834篇
  2006年   740篇
  2005年   655篇
  2004年   632篇
  2003年   608篇
  2002年   582篇
  2001年   505篇
  2000年   458篇
  1999年   411篇
  1998年   272篇
  1997年   231篇
  1996年   194篇
  1995年   167篇
  1994年   182篇
  1993年   156篇
  1992年   246篇
  1991年   237篇
  1990年   217篇
  1989年   218篇
  1988年   218篇
  1987年   172篇
  1986年   182篇
  1985年   176篇
  1984年   118篇
  1983年   125篇
  1982年   80篇
  1980年   68篇
  1979年   91篇
  1978年   84篇
  1977年   74篇
  1975年   104篇
  1974年   71篇
  1973年   64篇
  1972年   68篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
H P Haber  N Benda  G Fitzke  A Lang  M Langenberg  J Riethmüller    M Stern 《Gut》1997,40(3):406-411
BACKGROUND: Colonic strictures represent an advanced stage of fibrosing colonopathy in patients with cystic fibrosis. AIMS: To clarify whether ultrasonography can identify patients with an early stage of fibrosing colonopathy and to determine clinical factors that influence bowel wall thickening. PATIENTS: Ninety patients with cystic fibrosis, median age 10 years, and 46 healthy controls, median age 13 years, were investigated. METHODS: Bowel wall thickness was measured by ultrasound in a prospective study. RESULTS: In cystic fibrosis, wall thickness of both small intestine and colon was significantly (p < 0.0001) higher than in controls; 81% of patients with cystic fibrosis had a maximum colon wall thickness at any site of 2 mm or more, a value that was never reached by controls. The maximum colon wall thickness was 6.5 mm. Bowel wall thickness was unchanged at re-examination after one year. There was no progression even with high dose pancreatic supplements. There was no association between bowel wall thickness and clinical features such as previous meconium ileus, intestinal resection, distal intestinal obstruction syndrome, abdominal pain, or pancreatic enzyme dose. CONCLUSIONS: There is genuine intestinal involvement in cystic fibrosis; in a few cases this could lead to fibrosing colonopathy.  相似文献   
42.
43.
Alcohol consumption and glycosuria were found to be associated (p < 0.001) in a population of 6571 salaried employees who underwent a systematic examination. The prevalence of glycosuria was found to range from 1.3% among 2609 non-drinkers to 5% among 816 heavy drinkers (six glasses or more of alcoholic beverage daily). This association was still significant after adjustement for age, sex and body mass index. Similarly, a positive association was observed between fasting glycemia and alcoholic intake in a subgroup of 998 subjects when such a result was available (p < 0.05).  相似文献   
44.
45.
J. Lang 《Acta neurochirurgica》1994,130(1-4):144-146
  相似文献   
46.
Four human clonogenic malignant lymphoid cell lines (CEM, Su-DHL-4, Li-A, and Raji) as well as normal human bone marrow stem cell progenitor cells were investigated for clonal in vitro growth before and after incubation with the ether lipid ET-18-OCH3 for various times (1, 4, and 18 h) and at increasing concentrations of the drug (25, 50, 75, and 100 micrograms/ml). The clonal growth of the malignant lymphoid cell lines was inversely correlated with concentrations and times of drug incubation. The antineoplastic effect of ET-18-OCH3 was further amplified by subsequent cryopreservation. In a situation of 4-h exposure to less than or equal to 50 micrograms/ml ET-18-OCH3 and subsequent cryopreservation, in which greater than 50% of the normal human bone marrow progenitor cells survived, 1-3 logs of the malignant lymphoblastoid cells were killed, indicating a potential value of this drug for bone marrow purging in lymphoid malignancy. In order to simulate the situation of autologous bone marrow transplantation (ABMT) in complete remission of the disease, we contaminated normal human bone marrow cells with malignant CEM or Su-DHL-4 lymphoid cells at a ratio of 100:1. Results show that 4 h of incubation with 75 micrograms/ml ET-18-OCH3 and subsequent cryopreservation can eliminate 2-3 logs of clonogenic cells of the malignant lymphoblastoid cell lines under conditions that allow recovery of greater than 50% of the normal human hematopoietic progenitors.  相似文献   
47.
48.
Zusammenfassung Grundlagen Die pulmonale Thrombendarterektomie stellt eine effektive Therapie zur Behandlung von Patienten mit chronisch thromboembolischer pulmonalar Hypertonie dar. Wir berichten über unsere Erfahrungen mit dieser Operationstechnik bei den ersten 9 Patienten. Methodik Zwischen 1992 und Oktober 1994 wurde bei 9 Patienten eine pulmonale Thrombendarterektomie durchgeführt. über eine mediane Sternotomie wurden die Pulmonalarterien beider Seiten bis in ihre subsegmentalen Aufzweigungen im Sinne einer echten Endarterektomie vom organisierten thromboembolischen Material befreit. Zumeist waren Perioden des totalen Kreislaufstillstandes in tiefer Hypothermie notwendig, wobei diese zunehmend verkürzt werden konnten und 3 Patienten vollst?ndig ohne Kreislaufstopp operiert wurden. Ergebnisse Die perioperative Mortalit?t betrug 11%, wobei der 1. Patient am 14. postoperativen Tag an den Folgen eines Reperfusions?dems verstarb. Alle anderen Patienten sind 4 bis 22 Monate (im Mittel 13 Monate) nach dem Eingriff am Leben und zeigen eine Hochsignifikante Verbesserung ihrer h?modynamischen Situation (mean PAP pr?operativ: 62 mm Hg, postoperativ: 30 mm Hg p<0,001; Cardiac Index pr?operativ: 2,1 1/min/m2, postoperativ: 3,6 l/min/m2 p=0,001). W?hrend pr?operativ alle Patienten in NYHA-Klasse III oder IV waren, sind die 8 überlebenden jetzt alle in Klasse I oder II. Schlu?folgerungen Die pulmonale Thrombendarterektomie bietet eine erfolgreiche Therapiem?glichkeit für Patienten mit chronisch thromboembolischer pulmonaler Hypertonie mit einer in Anbetracht fehlender konservativer Altermativen akzeptablen Mortalit?t und ausgezeichneten funktionellen Langzeitergebnissen.   相似文献   
49.
Food policy and public health.   总被引:1,自引:0,他引:1  
T Lang 《Public health》1992,106(2):91-125
  相似文献   
50.
The results from a cohort study on the incidence of cancer and the mortality in a cohort of 2391 male workers producing magnesium metal are presented. The study population was restricted to employees with more than one year of work experience in the study plant between 1951 and 1974 and the cohort was observed from 1953 to 1984. Altogether 152 new cases of cancer were observed versus 132.6 expected. Six cases of cancer of the lip were found against 2.3 expected, 21 of stomach cancer against 12.8 expected, and 32 of lung cancer against 18.2 expected. A possible causal relation between exposure to factors in the work environment and the development of cancer is discussed.  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