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   928939篇
  免费   67591篇
  国内免费   1336篇
耳鼻咽喉   12955篇
儿科学   24345篇
妇产科学   23247篇
基础医学   132682篇
口腔科学   28227篇
临床医学   80262篇
内科学   182614篇
皮肤病学   19226篇
神经病学   72116篇
特种医学   36786篇
外国民族医学   79篇
外科学   152059篇
综合类   18015篇
现状与发展   1篇
一般理论   234篇
预防医学   61490篇
眼科学   21277篇
药学   72506篇
  3篇
中国医学   2161篇
肿瘤学   57581篇
  2018年   8972篇
  2017年   7037篇
  2016年   7768篇
  2015年   8871篇
  2014年   11992篇
  2013年   17507篇
  2012年   24111篇
  2011年   25050篇
  2010年   14815篇
  2009年   14273篇
  2008年   24613篇
  2007年   25697篇
  2006年   26503篇
  2005年   25438篇
  2004年   24570篇
  2003年   23609篇
  2002年   23154篇
  2001年   54730篇
  2000年   56547篇
  1999年   46958篇
  1998年   10735篇
  1997年   9468篇
  1996年   9599篇
  1995年   8925篇
  1994年   8251篇
  1993年   7569篇
  1992年   35465篇
  1991年   33925篇
  1990年   32735篇
  1989年   31870篇
  1988年   28978篇
  1987年   28249篇
  1986年   26280篇
  1985年   25144篇
  1984年   17815篇
  1983年   15119篇
  1982年   7766篇
  1981年   6739篇
  1979年   15759篇
  1978年   10584篇
  1977年   9027篇
  1976年   7859篇
  1975年   8617篇
  1974年   10455篇
  1973年   9851篇
  1972年   9355篇
  1971年   8848篇
  1970年   8418篇
  1969年   7918篇
  1968年   7199篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Forty samples of cord blood lymphocytes were isolated from 40 normal healthy full-term newborns. The initial 20 samples were used to determine the dose-response curve of three different thymic extracts (TP-1, bovine thymic extract; TG-15-I and TG-15-II, both porcine thymic extracts) and one of renal origin (KG-1) as a control of non-lymphoid organ extract, by measuring the E-rosette T cells. Results showed that E-rosette T cells increased significantly when the thymic extract concentration was increased to 12.5 micrograms/ml. However, there was no statistical difference between TP-1, TG-15-I and TG-15-II in the increase of E-rosette-forming cells. The remaining 20 samples were preincubated with 0, 12.5, 25 or 50 micrograms/ml of thymic extracts. It was observed that the lymphoproliferation, interleukin-2 (IL-2), gamma-interferon (IFN-gamma) and tumor necrotic factor (TNF) production were all significantly increased after thymic extract treatment. No statistical difference between these three thymic preparations in the stimulation of lymphoproliferative response was found. However, among the three thymic extracts, TP-1 appears to induce the highest amounts of IL-2, IFN-gamma and TNF. Of the TG-15-I and TG-15-II, the former stimulates higher IL-2 production whereas the latter enhances IFN-gamma and TNF production. The different immunostimulating effects and potencies that these three thymic extracts showed may reflect not only the species difference but also the difference in preparation procedures. Different components in these thymic extracts may be responsible for different biological activities. Results from these comparative studies may provide useful information in future clinical trials for the treatment of the primary immunodeficiency diseases according to their pathogenesis and may also indicate a possible beneficial effect of the combination of chemotherapy and thymic extracts.  相似文献   
992.
In summary, factors to consider in treatment are (1) the patient's age; (2) the flexibility of the condition; (3) the severity of deformity; (4) the presence of equinus; (5) abnormal shoe wear; and (6) the symptoms. When a child presents with severe flexible flatfoot one should rule out an underlying neuromuscular disorder and perform a complete biomechanical evaluation to ascertain any rotational or angular conditions of the legs that might influence the treatment. If a child is in group 1 (ages 4 to 7), a Helfet heel seat with a medial plantar wedge is usually adequate treatment. In the group II (ages 8 to 12) adolescent with flexible flatfoot, more control of the calcaneal eversion is needed. This is obtained by using a device constructed from a plaster mold taken while the foot is in neutral position. This UCBL type of device must usually extend to the metatarsal heads and be elevated on the medial and lateral sides. The group III (ages 13 to 17) adolescent usually has the additional problem of a forefoot varus, which must be controlled using a forefoot post. It is also not unusual to have to add additional wedging inside the heel of the shoe to invert the heel.  相似文献   
993.
Mycobacterium ulcerans infection in Ashanti region, Ghana   总被引:1,自引:0,他引:1  
We describe a series of 96 cases of Mycobacterium ulcerans infection (Buruli ulcer) from a new endemic focus in the Afram valley, north of Agogo, in Ghana. 63 cases were children under 13 years old. Active treatment by excision and skin grafting necessitates long stays in hospital and repeated procedures. Scarring and contracture are frequent. Eyes and other vital organs may be destroyed. In its endemic foci Buruli ulcer is a serious health burden on rural populations. Research is urgently needed, especially in prevention and non-surgical management.  相似文献   
994.
995.
996.
Alterations in the pulmonary surfactant system are partly responsible for the respiratory insufficiency seen with acute pancreatitis. In this model of cerulein-induced pancreatitis in rats, we utilized a new stable isotope metabolic tracer technique to examine one aspect of the pulmonary surfactant system and its relationship to associated lung injury. We have demonstrated primary, early depression of lung phospholipid synthesis reflected in both lung tissue and alveolar washings. We suggest that this quantitative change in pulmonary surfactant synthetic rate may partly explain the occurrence of respiratory failure with acute pancreatitis.  相似文献   
997.
W C Edwards  T J Orme  G Orr-Edwards 《Spine》1987,12(8):792-795
The purpose of this study is to analyze the prognostic value of discography followed by lumbar CT scanning in the selection of patients for chemonucleolysis. The overall success rate of chemonucleolysis in this series of 50 patients were 72%. The best results were obtained when the herniated disc fragment demonstrated a large uptake of contrast material visible by CT discography. The success rate of chemonucleolysis in this group of patients was 95%. Conversely, when the herniated fragment demonstrated no uptake of contrast material by CT discography, the success rate of the chemonucleolysis was 16%.  相似文献   
998.
The value of maternal C-reactive protein (CRP) levels as predictors of fetal and maternal infective morbidity and fetal mortality was assessed prospectively over a 6-month period in all cases of premature rupture of the fetal membranes or suspected premature labour. Statistical analysis of results showed that CRP at a level of 1.32 mg/dl is a sensitive marker of infective morbidity in mother and neonate. Furthermore, there was a significant association between raised CRP levels and low-birth-weight babies, suggesting that intra-uterine infection is a major cause of prematurity in the study population.  相似文献   
999.
Following the outbreak of poliomyelitis in Gazankulu in 1982, the immunisation services in Gazankulu were thoroughly examined. As a result of this, a comprehensive immunisation policy for Gazankulu was accepted in November 1986. The broad aim of the policy is to provide effective immunisation to all Gazankulu residents against tuberculosis, diphtheria, pertussis, tetanus, poliomyelitis and measles. A specific objective is that by the end of 1987, 85% of under-5s should have been vaccinated against these six diseases and by the end of 1990 this percentage should be 97%. The detailed strategies to reach these objectives are highlighted. Within the framework of the objectives, the policy allows different areas to formulate individual strategies. Programme monitoring and community involvement are two crucial aspects of the policy and these are discussed in detail. The early successes and difficulities in implementing this policy are discussed.  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