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   9248篇
  免费   453篇
  国内免费   42篇
耳鼻咽喉   113篇
儿科学   151篇
妇产科学   78篇
基础医学   1095篇
口腔科学   390篇
临床医学   511篇
内科学   2048篇
皮肤病学   169篇
神经病学   663篇
特种医学   314篇
外科学   1858篇
综合类   36篇
一般理论   1篇
预防医学   209篇
眼科学   148篇
药学   634篇
中国医学   11篇
肿瘤学   1314篇
  2023年   57篇
  2022年   102篇
  2021年   171篇
  2020年   96篇
  2019年   159篇
  2018年   180篇
  2017年   135篇
  2016年   188篇
  2015年   177篇
  2014年   249篇
  2013年   293篇
  2012年   498篇
  2011年   516篇
  2010年   333篇
  2009年   271篇
  2008年   450篇
  2007年   459篇
  2006年   457篇
  2005年   472篇
  2004年   442篇
  2003年   413篇
  2002年   430篇
  2001年   237篇
  2000年   249篇
  1999年   236篇
  1998年   102篇
  1997年   102篇
  1996年   88篇
  1995年   79篇
  1994年   91篇
  1993年   61篇
  1992年   188篇
  1991年   162篇
  1990年   163篇
  1989年   191篇
  1988年   160篇
  1987年   153篇
  1986年   134篇
  1985年   104篇
  1984年   74篇
  1983年   71篇
  1982年   37篇
  1980年   30篇
  1979年   63篇
  1978年   47篇
  1977年   46篇
  1974年   30篇
  1972年   41篇
  1971年   33篇
  1969年   30篇
排序方式: 共有9743条查询结果,搜索用时 15 毫秒
991.
992.
BACKGROUND: The purpose of this study is to evaluate the efficacy of postoperative adjuvant chemotherapy using uracil and tegafur (UFT) for colorectal cancer. METHODS: In a multicenter trial among 43 institutions for patients who underwent curative resection of Dukes' B or C colorectal cancer, a surgery alone group (control group) and a treatment group (UFT group) to which UFT was administered at 400 mg/day for 2 years following surgery were compared. A total of 320 patients were registered between March 1991 and April 1994, and 289 of these patients were analyzed as a full-analysis set. RESULTS: The 5-year disease-free survival rate was 75.7% in the UFT group and 60.1% in the control group, respectively, and the stratified log-rank test showed the statistical significance ( P=0.0081). This difference was marked in rectal cancer ( P=0.0016) and, in particular, the local recurrence was reduced. No significant difference was observed in the 5-year survival rate. The incidence of adverse reactions on administration of UFT was low, and there was no serious adverse reaction. CONCLUSION: It is suggested that the consecutive administration of UFT at 400 mg/day was an effective and highly safe therapeutic method as postoperative adjuvant chemotherapy for rectal cancer.  相似文献   
993.
The effects of long-term anticonvulsant therapy on copper (Cu), zinc (Zn), and magnesium (Mg) in the serum and hair were investigated in epileptics. Hair concentrations of Cu in both male and female epileptics, Zn in male epileptics, and Mg in female epileptics were significantly decreased when compared with those of age-matched and gender-matched controls. Hair Cu concentrations were significantly decreased in male epileptics; a significant decrease in hair Mg concentration was observed in female epileptics when compared with schizophrenics. An increased serum Cu concentration was found in female epileptics and a decreased Zn concentration was found in male epileptics. These findings suggest that long-term anticonvulsant therapy could induce alterations in both the metabolism and distribution of Cu, Zn, and Mg.  相似文献   
994.
Angiocentric immunoproliferative lesion (AIL) is the angiocentric and angiodestructive process of lymphoreticular cells with vascular invasion. AIL of the lung is rare. We treated a 57-year-old woman with AIL of the lung in whom chest radiography and computed tomography showed ground-glass opacity in the left lower lobe and lingular segment. Since macroscopical and intraoperative lung biopsy findings could not rule out the possibility of malignancy, including malignant lymphoma, we conducted left pneumonectomy. Immunohistological examination of the tumor showed that infiltrating lymphocytes consistent with AIL. Because tumor markers such as serum LDH and soluble IL-2 receptor increased postoperatively, we conducted systemic chemotherapy, after which elevated serum tumor markers decreased.  相似文献   
995.
The effects of 6-hydroxydopamine (6-OHDA) on the incidence, number and histology of colon tumors induced by azoxymethane (AOM), and on norepinephrine (NE) concentration in the colon wall and the labelling index of the colon mucosa were investigated in Wistar rats. Rats received sub-cutaneous (s.c.) injections of AOM once a week for 10 weeks, and throughout 35 weeks were also given intraperitoneal (i.p.) injections of 6-OHDA. Prolonged administration of 6-OHDA was found to cause a significant reduction in the incidence and number of colon tumors. However, it had no influence on the histological features or depths of involvement of colon tumors and/or adenocarcinomas. Its administration also caused significant decreases in the NE concentration in the colon wall and in the labelling index of the colon mucosa. Our findings indicate that 6-OHDA has a protective effect against colon carcinogenesis, and that the activity of the sympathetic nervous system may have an important influence on colon carcinogenesis.  相似文献   
996.
We have measured urinary tegafur (FT), 5-FU and uracil concentrations after UFT oral administration (300 mg daily for 7 days) to confirm drug-taking compliance in the 17 cases undergone gastrectomy. Urinary FT and 5-FU concentrations reached to the plateau 2 and 3 days after administration, respectively, and were maintained until the day after termination of administration. Subsequently, FT and 5-FU concentrations also decreased about 50% at 2 day, 20% at 3 day, 10% of the plateau values at 4 day after termination, respectively. The mean plateau value of urinary FT was 12.9 +/- 6.8 micrograms/dl, and that of urinary 5-FU was 0.67 +/- 0.50 microgram/dl. On the other hand, uracil concentration, was not different before and after administration because of the uracil being present endogenously. Therefore, it was suggested that measurement of urinary FT and 5-FU concentrations is useful for confirmation of UFT-taking compliance.  相似文献   
997.
Summary.  We have previously reported that ingenol derivatives are highly potent inhibitors of human immunodeficiency virus type 1 (HIV-1) replication in acutely infected cells. In this study, however, we have found that some ingenol derivatives strongly enhance the replication of HIV-1 in chronically infected cells at nanomolar concentrations. One of the derivatives could activate nuclear factor κB(NF-κB), a potent inducer of HIV-1 replication, through the activation of protein kinase C (PKC). Whereas another derivative, which affected neither PKC nor NF-κB, significantly enhanced HIV-1 replication, suggesting that a PKC-independent mechanism may also exist in ingenol derivative-induced HIV-1 upregulation. Received February 23, 1998 Accepted May 21, 1998  相似文献   
998.
999.
The Solitary thalamic abscess appears to be uncommon, 17 cases have been reported since 1973. We successfully treated a case of thalamic abscess associated with diabetes mellitus by sterotactic aspiration with external drainage. A 55 years old man presented right hemiparesis. A computed tomographic (CT) scan revealed solitary thalamic low density lesion with ringed contrast enhancement. We started the administration of antibiotics, but on the 9th day he became drowsy and his eyes were deviated downward and inward. CT scan on the 10th day showed the edema had been spread to the tectum. We aspirated purulent fluid material with confidence by sterotactic operation. We considered the mid brain tectum to be responsible for the downward and medial deviation of the eyes, because it appeared only when the edema and abscess were spread to that area, and disappeared after aspiration of the abscess with subsidence of the edema.  相似文献   
1000.
BACKGROUND: This study was designed to investigate the influence of intravitreal indocyanine green (ICG) on retinal morphology and function. METHODS: Brown Norway rats eyes ( n=24) were vitrectomized by the injection of 0.05 ml of 100% SF(6) gas. Two weeks later, ICG solution was injected into the vitreous cavity of vitrectomized eyes at a dose of 25 mg/ml, 2.5 mg/ml, 0.25 mg/ml or 0.025 mg/ml (0.05 ml/eye). Retinal toxicity was histologically assessed by light microscopy on day 10. The retinal function was also evaluated by electroretinography (ERG) in the low-dose groups (0.25 mg/ml and 0.025 mg/ml) after 10 days and again after 2 months,. Sham-operated eyes (SF(6) injected followed by 0.05 ml of BSS plus, n=6) were used as controls. RESULTS: In the high-dose group (25 mg/ml ICG), the retinal structure was severely deformed and the retinal pigment epithelium partly disappeared. In eyes with 2.5 mg/ml ICG, the retinal structure was also affected but less strongly so than with 25 mg/ml. No apparent pathologic change was observed in the low-dose groups (0.25 mg/ml or 0.025 mg/ml) by light microscopy. In contrast, 10 days later the amplitude of dark-adapted a- and b-waves of ERGs in the eyes of low-dose group rats were found to have decreased. In addition the light-adapted b-waves did not change significantly. These changes remained for 2 months. CONCLUSION: Even at a low dose (0.025 mg/ml), intravitreous ICG induced functional damage of the retina without any apparent morphological damage. This information should be taken into account when clinically administering ICG into the vitreous cavity.  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