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   824篇
  免费   67篇
  国内免费   40篇
耳鼻咽喉   7篇
儿科学   64篇
妇产科学   27篇
基础医学   142篇
口腔科学   27篇
临床医学   88篇
内科学   117篇
皮肤病学   6篇
神经病学   32篇
特种医学   64篇
外科学   108篇
综合类   27篇
预防医学   108篇
眼科学   8篇
药学   52篇
中国医学   2篇
肿瘤学   52篇
  2022年   6篇
  2021年   16篇
  2020年   10篇
  2019年   16篇
  2018年   22篇
  2017年   15篇
  2016年   19篇
  2015年   20篇
  2014年   26篇
  2013年   33篇
  2012年   49篇
  2011年   46篇
  2010年   38篇
  2009年   21篇
  2008年   34篇
  2007年   51篇
  2006年   42篇
  2005年   38篇
  2004年   44篇
  2003年   25篇
  2002年   30篇
  2001年   33篇
  2000年   31篇
  1999年   26篇
  1998年   15篇
  1997年   15篇
  1996年   12篇
  1995年   20篇
  1994年   12篇
  1993年   14篇
  1992年   15篇
  1991年   6篇
  1990年   9篇
  1989年   22篇
  1988年   8篇
  1987年   7篇
  1986年   7篇
  1985年   7篇
  1984年   7篇
  1983年   6篇
  1982年   13篇
  1981年   6篇
  1980年   6篇
  1979年   2篇
  1978年   3篇
  1977年   2篇
  1976年   6篇
  1975年   5篇
  1974年   5篇
  1971年   2篇
排序方式: 共有931条查询结果,搜索用时 15 毫秒
41.
OBJECTIVE: The purpose of this study was to evaluate 12-item General Health Questionnaire (GHQ-12) in screening for psychiatric morbidity after miscarriage. STUDY DESIGN: A prospective cohort study was carried out involving 222 patients. Six weeks after miscarriage, the GHQ-12 was applied. Psychiatric "case" or "non-case" was diagnosed by the psychiatrist with use of the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders-III-R. The patients were computer randomized into Groups A or B. A receiver operating characteristic (ROC) curve was constructed for Group A. The optimal cutoff value of GHQ-12 was determined, and this value was applied to Group B. The test characteristics were assessed. RESULTS: Twenty-seven patients were found to be psychiatric cases. An ROC with area under curve of 0.93 (95% CI 0.87-0.99, P<.001) was constructed. The best GHQ-12 cutoff score was > or =4 in detecting psychiatric caseness. A sensitivity of 83%, specificity of 90%, positive predictive value of 50%, and negative predictive value of 98% were obtained. CONCLUSION: GHQ-12 is an effective screening tool in detecting psychiatric morbidity after miscarriage.  相似文献   
42.
Background and Aims: Over the past few decades, the prevalence of asthma has been increasing in the industrialised world. Despite the suggestion of a similar increase in Singapore, the 12 month prevalence of wheeze among schoolchildren in 1994 was 2.5-fold less than that reported in western populations. It was hypothesised that with increasing affluence in Singapore, the asthma prevalence would further increase and approach Western figures. A second ISAAC survey was carried out seven years later to evaluate this hypothesis. Methods: The cross-sectional data from two ISAAC questionnaire based surveys conducted in 1994 (n = 6238) and in 2001 (n = 9363) on two groups of schoolchildren aged 6–7 and 12–15 years were compared. The instruments used were identical and the procedures standardised in both surveys. Results: Comparing data from both studies, the change in the prevalence of current wheeze occurred in opposing directions in both age groups—decreasing in the 6–7 year age group (16.6% to 10.2%) but increasing to a small extent in the 12–15 year age group (9.9% to 11.9%). The 12 month prevalence of rhinitis did not change; there was an increase in the current eczema symptoms in both age groups. Conclusion: The prevalence of current wheeze, a surrogate measure of asthma prevalence, has decreased significantly in the 6–7 year age group. Eczema was the only allergic disease that showed a modest increase in prevalence in both age groups.  相似文献   
43.
Objective: In laparoscopic colorectal procedures, the presence of peritoneal adhesions caused by previous surgery is one of the most common reasons for conversion and is often associated with increased postoperative morbidity. However, improvements in laparoscopic technique and instruments might, to some extent, help to overcome the adverse effects of peritoneal adhesions. Therefore, the present study was designed to compare and evaluate laparoscopic rectal cancer excision in patients who had had and who had not had previous abdominal surgery. Methods: The present study was a non‐randomized comparison of patients who have had and have not had previous abdominal surgery. Data were extracted from a prospective cohort of patients who had undergone laparoscopic anterior resection for rectal cancer in one particular unit between January 1996 and May 2000. For the purpose of standardization, data on laparoscopic low anterior resection and laparoscopic abdomino‐perineal resection were not used for analysis. The measured outcomes included operation time, blood loss and length of hospital stay as well as complications and conversions. Results: Of the 91 patients recruited for analysis, 26 patients had had previous abdominal surgery (study group), whereas 65 patients had not had previous abdominal surgery (control group). The two groups had a similar age and gender distribution as well as tumour staging. The median operating times of the study group and control group (115 vs 123 min, P = 0.34), their blood loss (122 vs 144 mL, P = 0.30) and lengths of hospital stay (10 vs 11 days, P = 0.66) were similar. The complication rates (23 vs 23%, P = 0.79) and conversion rates (15.4 vs 7.7%, P = 0.55) were also similar between the two groups. Conclusion: Laparoscopic resection for rectal cancer in patients who have had previous abdominal surgery is technically safe and produces similar results to those who have not had previous abdominal surgery.   相似文献   
44.
45.
Transforming growth factor beta-1 (TGF-beta 1) plays a pivotal role in tissue fibrogenesis. Understanding the factors that control resolution of fibrosis is critical to devising means to combat clinical fibrosis. Future challenges would include designing ways to block the fibrosis-specific actions of TGF-beta.Blockade of transforming growth factor beta (TGF-beta) activity in vivo in animal models has proven to be an effective means of inhibiting the fibrotic response to injury in various organs. Similarly, transgenic animals in which TGF-beta 1 expression is artificially enhanced show marked spontaneous fibrosis or increased fibrotic response to injury. TGF-beta is known to effect fibroplasias, not only by its well known action of increasing extracellular matrix synthesis but also by coordinately regulating key proteins which mediate connective tissue homeostasis. This includes down-regulation of interstitial collagenase and other matrix metalloproteinases and up-regulation of antiproteases such as tissue inhibitor of metalloproteinase I and plasminogen activator inhibitor. Whilst inhibition of TGF-beta activity appears to be well tolerated in rodents over several weeks, the ultimately lethal phenotype of TGF-beta 1 knockout mice warns us that this pluripotent cytokine is essential for normal health. Therefore, downstream pathways activated by TGF-beta, which might be specific for its fibrotic effects, might be more useful targets for human fibrotic disease therapy. For example, the TGF-beta response protein connective tissue growth factor may be a good target for antifibrotics but definitive evidence awaits development of suitable genetically modified animal models and specific inhibitors.  相似文献   
46.
Acute viral respiratory tract infections are a significant cause of morbidity worldwide. Information on the epidemiology and seasonality of these infections is important in planning vaccination and treatment strategies. In temperate climes, there are distinct seasonal peaks in the winter months. This paper reviews the seasonal trends of respiratory viral infections in the tropics. Despite the absence of a winter season, consistent seasons of infection, albeit less distinct, have been observed. With few exceptions, respiratory syncytial virus and influenza infections have been observed mainly during the rainy seasons in Asian, African and South American countries.  相似文献   
47.
Fetal sacrococcygeal teratoma can lead to a high output cardiac failure resulting in hydrops fetalis. One of the prenatal therapeutic options is to occlude the feeding vessels by radiofrequency ablation. We present a case of fetal sacrococcygeal teratoma diagnosed at 13 weeks of gestation. The tumour increased in size more than 100 fold over 5 weeks causing polyhydramnios and cardiac and placental enlargement. Thermocoagulation was performed at 18 weeks' gestation by passing an insulated electric wire through an 18 gauge needle placed close to the feeding vessels of the tumour at its neck. Blood supply to the tumour was successfully reduced. However, fetal death was diagnosed 2 days after the procedure. We speculate that it may be safer to limit the extent of coagulation in one attempt but to repeat the procedure at a later stage when necessary.  相似文献   
48.
We prospectively studied 66 patients infected with the hepatitis B virus who underwent liver resection for hepatocellular carcinoma (HCC) to evaluate the influence of the histologic activity of noncancerous liver tissue on clinicopathologic features and prognosis. Based on the histologic activity index (HAI) score of nontumorous liver tissue, patients were classified into 3 groups: mild, moderate, or severe hepatitis. Overall, higher HAI scores were more frequent in patients with poorer liver function: lower serum albumin levels and higher indocyanine green retention at 15 minutes. Moreover, patients with moderate hepatitis had more frequent venous invasion, and the tumor size decreased with increasing HAI scores. Similar results were observed when the fibrosis category was excluded in the calculation of HAI scores. The overall or disease-free survival rates did not differ significantly among the 3 groups of patients. However, higher fibrosis scores were associated significantly with shorter disease-free survival rates. HAI scores correlated significantly with certain clinicopathologic features. In patients with hepatitis B-related HCC, a higher fibrosis score in the nontumorous liver tissue, but not histologic hepatitic activity, seems to be a significant factor predisposing to shorter survival.  相似文献   
49.
Analyses of adolescent suicide statistics in Hong Kong for the period 1980 to 2000 revealed several phenomena. First, while adolescent suicide rates (10-24 age group) in Hong Kong were relatively stable for the period under study, there was a gradual rising trend where adolescent suicide rates in the 1990s were higher than those in the 1980s. Second, suicide rates for adolescents aged 10-24 were lower than those of other adult age groups. Third, while adolescent suicide rates in Hong Kong were lower than those reported in some English-speaking countries and Mainland China, the figures were higher than those reported in Taiwan. Fourth, suicide rates among teenagers in early adolescence were lower than those among adolescents in late adolescence. Fifth, although male adolescent suicide rates were in general higher than female adolescent suicide rates (10-24 age group), gender differences in suicide rates appeared to be moderated by age. Sixth, there was a gradual rising trend in adolescent proportional mortality rates for suicide in the 1990s. Seventh, proportional mortality rates for suicide among teenagers in early adolescence were lower than those among adolescents in late adolescence. Finally, while jumping from a height was a common method of adolescent suicide, there was a rising trend of using other methods such as taking drugs, hanging and charcoal burning. The observed adolescent suicide phenomena are discussed with reference to the socio-cultural context of Hong Kong.  相似文献   
50.
An unusual case of avulsion fracture of the tibial tuberosity with underlying angiomatosis in a middle-aged man is described, with particular emphasis on the successful use of bisphosphonate in its treatment and the value of serial dual energy X-ray absorptiometry in its subsequent disease monitoring. This case illustrates the importance of careful correlation of the clinical, radiological, and histological findings in the management of skeletal tumour and tumour-like lesions. The differential diagnosis of osteolysis with vascular ectasia 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