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   5970篇
  免费   345篇
  国内免费   26篇
耳鼻咽喉   20篇
儿科学   170篇
妇产科学   143篇
基础医学   792篇
口腔科学   94篇
临床医学   359篇
内科学   1547篇
皮肤病学   191篇
神经病学   345篇
特种医学   218篇
外科学   1209篇
综合类   14篇
预防医学   138篇
眼科学   63篇
药学   261篇
中国医学   1篇
肿瘤学   776篇
  2023年   57篇
  2022年   104篇
  2021年   162篇
  2020年   71篇
  2019年   97篇
  2018年   139篇
  2017年   117篇
  2016年   144篇
  2015年   175篇
  2014年   174篇
  2013年   230篇
  2012年   387篇
  2011年   417篇
  2010年   210篇
  2009年   207篇
  2008年   391篇
  2007年   367篇
  2006年   428篇
  2005年   363篇
  2004年   391篇
  2003年   378篇
  2002年   379篇
  2001年   80篇
  2000年   58篇
  1999年   78篇
  1998年   88篇
  1997年   76篇
  1996年   70篇
  1995年   56篇
  1994年   61篇
  1993年   54篇
  1992年   37篇
  1991年   48篇
  1990年   38篇
  1989年   28篇
  1988年   22篇
  1987年   16篇
  1986年   16篇
  1985年   8篇
  1984年   16篇
  1983年   12篇
  1982年   6篇
  1981年   14篇
  1980年   5篇
  1979年   9篇
  1978年   11篇
  1977年   9篇
  1976年   5篇
  1975年   5篇
  1973年   8篇
排序方式: 共有6341条查询结果,搜索用时 156 毫秒
81.
Summary The erythrocyte band 3 (EPB3) variant, band 3 Memphis (EPB3*Memphis), was detected by immunoblotting with a monoclonal antibody to the 41 kDa cytoplasmic N-terminal domain of band 3 without protease treatment of erythrocytes. EPB3*Memphis was also detected by immunoblotting from 3-month-old bloodstains subjected to -chymotrypsin treatment. A population genetic study using this method indicated that the EPB3 variant would be useful for forensic work in Japan, since the frequency of this variant in Japanese (Wakayama prefecture) is relatively high (0.159).  相似文献   
82.
PURPOSE: Angiogenesis plays an important role in a multitude of biological processes including those of tumorigenesis and cancer progression. Hypoxia is the prime driving factor for tumor angiogenesis and the family of hypoxia-inducible factors (HIFs) plays a pivotal role in this process. The role of HIF in tumor angiogenesis has been underscored in different carcinomas but yet to be reported for colorectal carcinomas. EXPERIMENTAL DESIGN: In this study, we examined HIF [HIF-1alpha (HIF1) and HIF-2alpha (HIF2)] expression in 87 curatively resected colorectal carcinoma samples, and the results were correlated with clinicopathological factors, microvessel density, cyclooxygenase 2 expression, and patient prognosis. RESULTS: HIF1 (44.8%) was more frequently expressed than HIF2 (29.9%). Most of the clinicopathological factors representing the tumor aggressiveness were significantly correlated with overexpression of HIF2 but not with HIF1 expression. HIF2 expression had direct correlation with microvessel density and cyclooxygenase 2 expression. and, in contrast, HIF1 expression had a weak but significant inverse correlation in T1 and T2 tumors only. HIF2 expression alone and the combined expression of HIF1 and HIF2 had significant impact on patient survival. In the multivariate analysis, however, only the combined expression of HIF1 and HIF2 remained independently significant. CONCLUSIONS: Taken together, our results suggest that HIF2 expression may play an important role in angiogenesis and that the combined expression of HIF1 and HIF2 may play an important role in tumor progression and prognosis of colorectal carcinomas. Therefore, HIF expression could be a useful target for therapeutic intervention.  相似文献   
83.
Abstract We report here a case of neonatal hyperthyroidism born to a mother, whose pregnancy was complicated by poorly controlled Graves' disease. The patient demonstrated exophthalmos and marked goiter at birth, indicating the existence of thyrotoxicosis in utero. The mother's Graves' disease was well controlled in the third trimester, resulting in a slightly lower level of free thyroxine (FT4) in the umbilical cord blood serum; however, thyroid-stimulating hormone (TSH) was undetectable. Thyroid-stimulating hormone remained undetectable for 2 months, while FT4 levels varied in the course. This case suggests that severe and prolonged thyrotoxicosis in utero, due to poor control of pregnancy with Graves' disease, might induce unresponsiveness of the hypothalamo-pituitary system in the newborn.  相似文献   
84.
OBJECTIVE: To investigate maternal and neonatal outcomes after antioxidant supplementation relatively early in pregnancy (8 to 12 weeks) for pregnant women with low antioxidant status. METHODS: A randomized, double-blind, placebo-controlled trial of daily antioxidant supplementation was performed on pregnant women screening positive for low antioxidant status at 8 to 12 weeks of gestation. Low antioxidant status was defined as a superoxidedismutase (SOD) level below 1102 U/g Hb or 164 U/mL. The supplementation group received the following antioxidants daily: vitamins A (1000 IU), B6 (2.2 mg), B12 (2.2 microg), C (200 mg), and E (400 IU), folic acid (400 microg), N-acetylcysteine (200 mg), Cu (2 mg), Zn (15 mg), Mn (0.5 mg), Fe (30 mg), calcium (800 mg), and selenium (100 microg). The control group received Fe (30 mg) and folic acid (400 microg). Maternal (preeclampsia, abortion, and hypertension) and perinatal outcomes were assessed. RESULTS: In the supplementation group (29 subjects), we observed 2 cases of preeclampsia (6.8%, 1 mild and 1 severe), 1 of IUGR (birth weight 2300 g at 38 weeks), and 1 preterm delivery. In the control group (31 subjects), there were 8 abortions, 9 cases of preeclampsia (29%, 6 mild and 3 severe) with perinatal outcome: 3 preterm delivery cases and 1 IUGR (birth weight 2030 g at 39 weeks). Preeclampsia was significantly less frequent in the supplementation group when compared to the control group (2 vs. 9 cases, p = 0.043, OR = 0.18 [95% CI: 0.03, 0.92]). Finally we focused on the prediction of preeclampsia at 8 to 12 weeks. Combined sensitivity of markers of antioxidant status (SOD slutathione peroxidase, [GPx], and total anti-oxidant status [TAS]) was 33% (false-positive rate of 4.5%). CONCLUSION: Antioxidant supplementation was associated with better maternal and perinatal outcome in pregnant women with low antioxidant status than control supplementation with iron and folate alone. In a selected population already screened positive for low SOD, preeclampsia can be detected in 33% of asymptomatic cases in the first trimester using SOD, GPx, and TAS. It seems feasible that panels of both biochemical and molecular markers may be clinically useful in the prediction of this disease.  相似文献   
85.
A chronic combined toxicity and carcinogenicity study of S-170, a sucrose fatty acid ester, was performed in male and female F344 rats. S-170 was given ad libitum in the diet at levels of 0, 1.25, 2.5 or 5% to 10 rats/sex/group for 12 months to determine chronic toxicity and 0, 2.5 or 5% to 50 rats/sex/group for two years in the carcinogenicity study. Treatment with S-170 exerted no effect on survival in either sex. In the 12-month chronic toxicity study, no treatment-related effects on body weights, or hematological, blood biochemical, urinary and pathological parameters were demonstrated in any of the treated groups. In the carcinogenicity study, S-170 did not cause any dose-related significant increase in the incidences of tumors in any organs or tissues. Taken together, the results clearly demonstrate that S-170 has neither toxic nor carcinogenic activity in F344 rats under the conditions of the study. No observed adverse effect levels (NOAELs) calculated from the 12-month chronic toxicity and carcinogenicity study were 2.37 g/kg/day in males and 2.80 g/kg/day in females, and 2.12 g/kg/day in males and 2.42 g/kg/day in females, respectively.  相似文献   
86.
We report a patient with congenital Chagas disease in Japan. This report reemphasizes the role of neglected and emerging tropical diseases in the era of globalization. It also indicates the need for increased vigilance for detecting Chagas disease in non–disease-endemic countries.  相似文献   
87.
88.
89.
90.
Atypical progeroid syndrome (APS), including atypical Werner syndrome (AWS), is a progeroid syndrome involving heterozygous mutations in the LMNA gene encoding the nuclear protein lamin A/C. We report the first Japanese case of APS/AWS with a LMNA mutation (p.D300N). A 53‐year‐old Japanese man had a history of recurrent severe cardiovascular diseases as well as brain infarction and hemorrhages. Although our APS/AWS patient had overlapping features with Werner syndrome (WS), such as high‐pitched voice, scleroderma, lipoatrophy and atherosclerosis, several cardinal features of WS, including short stature, premature graying/alopecia, cataract, bird‐like face, flat feet, hyperkeratosis on the soles and diabetes mellitus, were absent. In immunofluorescence staining and electron microscopic analyses of the patient's cultured fibroblasts, abnormal nuclear morphology, an increase in small aggregation of heterochromatin and a decrease in interchromatin granules in nuclei of fibroblasts were observed, suggesting that abnormal nuclear morphology and chromatin disorganization may be associated with the pathogenesis of APS/AWS.  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