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   2440篇
  免费   123篇
  国内免费   25篇
耳鼻咽喉   14篇
儿科学   192篇
妇产科学   23篇
基础医学   271篇
口腔科学   54篇
临床医学   202篇
内科学   617篇
皮肤病学   42篇
神经病学   114篇
特种医学   502篇
外科学   195篇
综合类   29篇
预防医学   90篇
眼科学   28篇
药学   74篇
中国医学   5篇
肿瘤学   136篇
  2023年   6篇
  2022年   18篇
  2021年   26篇
  2020年   20篇
  2019年   33篇
  2018年   39篇
  2017年   28篇
  2016年   33篇
  2015年   50篇
  2014年   48篇
  2013年   90篇
  2012年   67篇
  2011年   69篇
  2010年   94篇
  2009年   90篇
  2008年   66篇
  2007年   67篇
  2006年   70篇
  2005年   54篇
  2004年   56篇
  2003年   53篇
  2002年   58篇
  2001年   40篇
  2000年   70篇
  1999年   63篇
  1998年   141篇
  1997年   119篇
  1996年   131篇
  1995年   97篇
  1994年   76篇
  1993年   83篇
  1992年   30篇
  1991年   32篇
  1990年   18篇
  1989年   73篇
  1988年   52篇
  1987年   52篇
  1986年   50篇
  1985年   50篇
  1984年   26篇
  1983年   33篇
  1982年   36篇
  1981年   22篇
  1980年   36篇
  1979年   15篇
  1978年   15篇
  1977年   17篇
  1976年   23篇
  1975年   25篇
  1968年   6篇
排序方式: 共有2588条查询结果,搜索用时 15 毫秒
51.
OBJECTIVE: The effects of neuropsychological treatment on cognitive hypofrontality were examined in schizophrenic patients through the score activation. METHOD: Eight subjects (six men and two women) with persistent negative symptoms and cognitive impairments were evaluated with single photon emission computed tomography (SPECT) procedures and neuropsychological battery before and after a neuropsychological treatment group. RESULTS: After treatment an enhancement in neuropsychological performance was found, especially in executive functions. The activation score showed an increase over baseline levels and no cognitive-dependent hypofrontality after treatment was found. Although the prefrontal blood flow changes were small and non-specific, they suggest a reduction of the cognitive hypofrontality after neuropsychological treatment. CONCLUSION: Cognitive improvements after neuropsychological treatment would possibly be related with the diminution of the functional hypoactivity in the prefrontal areas.  相似文献   
52.
53.
Patients with head and neck cancers can develop salivary hypofunction after radiotherapy. The use of pilocarpine during radiotherapy treatment has been shown to be an effective treatment, although its usefulness is being discussed. The aim of this study was: (1) to determine the value of a semiquantitative scintigraphy method for measuring the uptake and excretory salivary function of patients with head and neck irradiated tumours; and (2) to study the usefulness of pilocarpine as a salivary gland protector during radiotherapy. We prospectively studied 49 patients (mean age 61 years, range 29-87 years) with head and neck cancer in need of radiotherapy. Patients were divided into two groups consecutively: group P (26 patients) received 5 mg of pilocarpine three times per day starting the day before radiation therapy, and group NP (23 patients) received radiotherapy without pilocarpine and were used as the control group. Salivary gland scintigraphy and a visual analogue scale (VAS) of mouth dryness were obtained from each patient before radiotherapy and during the first year after treatment. The most frequent finding after radiotherapy was a quick impairment in parotid and submaxillary excretion (P < 0.001). There were no statistical differences comparing the pilocarpine group against the non-pilocarpine group. Parotid and submaxillary uptake significantly decreased after radiotherapy in both groups (P < 0.001). However, a tendency to recover within the pilocarpine group was observed in both the parotids and the submaxillary glands at 12 months. No differences were found comparing the VAS results in both groups. Strikingly, VAS data did not correlate with salivary gland dysfunction observed by means of scintigraphy. In conclusion, salivary scintigraphy is a useful technique to evaluate objectively the salivary gland function of patients with head and neck irradiated tumours as well as to test the response to pilocarpine. However, despite better results on the salivary uptake at 12 months, pilocarpine did not significantly improve salivary gland function.  相似文献   
54.
55.
OBJECTIVES: To evaluate the usefulness of Phe loading test in patients for the diagnosis of guanosine triphosphate cyclohydrolase 1 deficiency (GTPCH). DESIGN AND METHODS: We studied one family composed of 13 members harbouring the Q89X mutation in the GTPCH gene, a non-related pediatric patient with GTPCH deficiency and 8 pediatric controls. 100 mg/kg of L-phenylalanine was orally administered, and blood spot samples were taken at baselines 1, 2, 4 and 6 h post-load. RESULTS: Two out of 7 pediatric patients showed a phenylalanine/tyrosine ratio higher than the previously reported cut-off value of 5.25 at 4 h, while 6 of the 7 adult patients showed a higher value. The only adult patient with a phenylalanine/tyrosine ratio below 5.25 at 4 h was asymptomatic. CONCLUSIONS: A cut-off value of 5.25 seems reliable for interpreting Phe loading test in adult patients with GTPCH deficiency, although a lower value should be established for pediatric patients.  相似文献   
56.
Rats with nitrofen-induced congenital diaphragmatic hernia (CDH) have heart hypoplasia and cardiovascular malformations. The mechanism of action of nitrofen involves changes in neural crest signaling. Pax3 function is required for cardiac neural crest cells to complete their migration to the developing heart. The aim of this study was to examine whether Pax3 expression is changed at two gestational endpoints in rat embryos or fetuses exposed to nitrofen. On day E9.5 of gestation, pregnant rats received either 100 mg of nitrofen (n=10) or vehicle alone (control, n=10). The fetuses were recovered on E15 or E21. Their hearts were dissected out and weighed. Pax3 mRNA expression was determined by real-time polymerase chain reaction. We used two-tailed Students t-tests to compare groups, with a threshold of significance of p<0.05. Compared with controls, nitrofen-exposed fetuses had heart hypoplasia in terms of heart/body weight ratio (0.62±0.10% vs. 0.77±0.17%, p<0.05). Pax3 mRNA expression in the heart was significantly decreased on E15 in nitrofen-treated embryos (32.94±17.11 U vs. 55.09±11.56 U, p<0.05), and it was still decreased, although not significantly, in the hearts of nitrofen-exposed fetuses recovered on E21 (15.67±5.56 U vs. 20.51±5.92 U, not significant). In conclusion, Pax3 is underexpressed in the hearts of nitrofen-exposed embryonal rats before the end of gestation. The mechanism of action of Pax3 should be further investigated because it could be one of the targets for future prenatal transplacental intervention.Paper presented at the XVIIth International Symposium of Pediatric Surgical Research, Liverpool, United Kingdom, 1–2 October, 2004.  相似文献   
57.
Oncohaematological patients present a high incidence of infections, which are one of the principle causes of morbidity and mortality. There are different types of immunodepression related to the disease, the moment of its evolution and the treatment received. For practical purposes we will distinguish between patients with severe neutropenia, those with some alteration to humoral immunity and, finally, cellular immunodeficiencies. There are no immunodeficiencies associated to each disease, instead several immunitarian deficiencies can be associated in a single clinical entity. Neutropenic patients, generally with acute leukaemias and following intensive chemotherapy, have bacterial and fungal infections conditioned by the intensity and duration of the neutropenia. In the case of patients with humoral immunodeficiency (multiple myeloma, chronic lymphatic leukaemia, splenectomised) there are frequent infections by encapsulated germs. When there is cellular immunodepression (Hodgkin's disease, advanced chronic lymphoproliferative syndromes, treatment with glucocorticoids, analogues of the purines and treatment with monoclonal antibodies) the risk of infection by opportunist germs is conditioned by the reduction of the figure of CD4 lymphocytes. We review the different strategies of prophylaxis and treatment in each of the situations.  相似文献   
58.
59.
60.
Aim: Electrical burns account for up to 10% of burns admissions worldwide. Although a potentially serious mechanism of injury in children, there exists limited Australian data. This study aimed to describe the epidemiology, presentation, management and complications of electrical burn injuries in children. Methods: We performed a retrospective case note review of all children under 16 years of age with electrical burns admitted to the New South Wales Paediatric Burns Centre over an 8‐year, 2‐month study period between November 1995 and December 2003. Results: Twenty‐two cases were identified. The mean age at presentation was 7.6 years (range 8 months to 14.3 years). Eighty‐six percent of cases were sustained from a Low Voltage (<1000 W) power source and 55% occurred in males. The total body surface area burnt ranged from 0.5% to 35% with an average of 4%. Fourteen children had their burns managed non‐operatively, but eight required various surgical procedures ranging from local debridement and primary closure to full‐thickness skin grafting. The average length of hospital stay was 6 days (range 1–58 days). Complications occurred in 4 of the 22 patients (18%) and included wound infections, acute renal failure because of myoglobinuria, permanent electrocardiogram changes and long‐term paraesthesia. Three patients (14%) suffered continued morbidity because of scarring, amputation and psychological disturbance. There was no mortality. Conclusions: Electrical injury was an infrequent but potentially serious cause of injury in children. Minor injuries were successfully managed non‐operatively. Neurological sequelae, cardiac arrhythmias and renal failure remain serious complications in up to 20% of cases.  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