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   1826篇
  免费   115篇
  国内免费   13篇
耳鼻咽喉   27篇
儿科学   31篇
妇产科学   22篇
基础医学   288篇
口腔科学   37篇
临床医学   103篇
内科学   421篇
皮肤病学   44篇
神经病学   166篇
特种医学   39篇
外科学   283篇
综合类   7篇
预防医学   70篇
眼科学   49篇
药学   123篇
中国医学   10篇
肿瘤学   234篇
  2024年   1篇
  2023年   20篇
  2022年   47篇
  2021年   90篇
  2020年   50篇
  2019年   56篇
  2018年   61篇
  2017年   47篇
  2016年   60篇
  2015年   49篇
  2014年   69篇
  2013年   91篇
  2012年   156篇
  2011年   143篇
  2010年   88篇
  2009年   47篇
  2008年   126篇
  2007年   87篇
  2006年   105篇
  2005年   107篇
  2004年   96篇
  2003年   81篇
  2002年   93篇
  2001年   32篇
  2000年   32篇
  1999年   23篇
  1998年   13篇
  1997年   12篇
  1996年   15篇
  1995年   14篇
  1994年   2篇
  1993年   7篇
  1992年   6篇
  1991年   2篇
  1990年   4篇
  1989年   5篇
  1988年   6篇
  1987年   2篇
  1985年   4篇
  1983年   2篇
  1968年   1篇
  1966年   1篇
  1964年   1篇
排序方式: 共有1954条查询结果,搜索用时 265 毫秒
131.
132.
Results of three experiments, in which a total of 167 students participated, consistently indicated that participants performed recognition tasks better for face photographs of defectors than those of cooperators. The face photographs used in the experiments were those of participants taken during prisoner's dilemma (PD) experiments a few years prior to the present study. In Experiments 1 and 2, photographs of cooperators and defectors in a one-shot PD experiment, taken after they had filled out a lengthy post-experimental questionnaire, were used. In Experiment 3, the photographs were those of high and low cooperators, taken at the moment of a cooperation or defection choice, respectively. Recognition was better for photographs that were judged unattractive than attractive. At the same time, it was better for photographs of less cooperative participants in the PD studies than those of more cooperative participants. Implications of the findings for Cosmides & Tooby's (1992) 'cheater-detection' module for social exchange domain were discussed.  相似文献   
133.
OBJECTIVE: The goal of this study was to report the delivery outcomes in women who had loop electrosurgical excision procedure (LEEP) for microinvasive cervical cancer (stage IA1 without lymphovascular invasion) and became pregnant and progressed beyond 24 weeks. METHODS: A case-control study was performed. Twenty-eight women who were managed exclusively with LEEP for microinvasive cervical carcinoma had at least one pregnancy beyond 24 weeks and were the cases. Each case was matched with one woman who delivered at the same department without prior treatment of her cervix (controls) and their delivery outcomes were compared with those of the cases. Known risk factors for preterm delivery were used as matching factors. RESULTS: There was no statistically significant difference (P > 0.05) between cases and controls in the duration of pregnancy (37.6-38.4 weeks respectively), birth weight (3212-3315 g), cesarean section rate (17.8-32.1%), neonatal unit admission rate (21.4-10.7%), and precipitate labor rate (13-10.5%). The duration of labor was significantly shorter in cases (5.5-7.1 h, P = 0.032). After LEEP the relative risk for preterm delivery is 3.67 (95% confidence interval, 0.97-20.27), for low birth weight infant 0.67 (0.06-5.8), for precipitate labor 1 (0.05-3.88), and for delivery by cesarean section 0.5 (0.17-4.46). CONCLUSIONS: Women treated for microinvasive cancer with LEEP did not have significantly more delivery complications compared with controls apart from shorter duration of labor. There was a possible non-statistically significant trend toward shorter duration of pregnancy in cases. While caution should be advised when selecting and treating women with microinvasive carcinoma by LEEP, the apparent safety of the management and the satisfactory delivery outcome seem to justify this approach in many cases.  相似文献   
134.
OBJECTIVES/HYPOTHESIS: Cyclin D1, a cell cycle regulator localized to chromosome 11q13, is amplified in several human tumors including head and neck squamous cell carcinoma (HNSCC). Amplification and/or overexpression of cyclin D1 have been correlated to a poor prognosis. Deletion of the p16 gene, localized to 9p21, has also been observed in a significant proportion of HNSCC. The p16 gene regulates cyclin D1-CDK4 activity and prevents retinoblastoma tumor suppressor gene phosphorylation, thereby downregulating cellular proliferation. Detection of cyclin D1 amplification and p16 deletion using a simple and sensitive method will be valuable for the development of effective treatment modalities for head and neck cancer. STUDY DESIGN: We have used fluorescence in situ hybridization (FISH) to study cyclin D1 amplification and p16 gene deletion in head and neck tumors. Both single- and dual-color FISH were performed. METHODS: Paraffin-embedded tissues from 103 patients with HNSCC were analyzed using genomic DNA probes for cyclin D1 and p16. Dual-color FISH was performed with chromosome 11 or 9 centromeric probes as a control. Twenty-eight of these samples were analyzed for p16 expression by immunohistochemistry. RESULTS: Cyclin D1 amplification was observed in 30% (31/103) of patients, and p16 deletion in 52% (54/103). Lack of p16 expression was observed in 64% (18/28) of patients. There was a good correlation between the deletion of p16 sequences and the loss of p16 expression (P = .008). Amplification of cyclin D1 had a statistically significant association with recurrence, distant metastasis, and survival at 36 months. There was a significant association between p16 deletion and the development of distant metastases. Cyclin D1 amplification and p16 deletion together correlated with recurrence, distant metastasis, and survival. CONCLUSIONS: We demonstrate that FISH is a simple and sensitive method for detecting cyclin D1 amplification and p16 deletion in head and neck cancer. Our results suggest that these two genetic aberrations together portend a poorer outcome than either of the abnormalities alone in head and neck cancer.  相似文献   
135.
Firstly, we designed a vein-implantation model using the rat femoral nerve and vein to study the morphometric changes in nerve endings inserted into venous lumina. By 4 weeks, nerve fibers had extended from the nerve stump into the lumen of the vein and along the endothelium of the vein. After 8 weeks, the lengths and number of nerve fibres extending into the vein lumen began to decrease. At 12 weeks, the nerve ending had developed a hemispherical shape. In none of the experiments was a neuroma formed. Secondly, we treated ten neuromas in ten patients by the vein-implantation method. We obtained excellent results in seven patients.  相似文献   
136.
137.
PURPOSE: In the treatment of age-related macular degeneration (AMD), the effect on the fovea of photocoagulation of juxtafoveal choroidal neovascularization(CNV) and extrafoveal CNV near the fovea has been of concern, and so usefulness of surgical excision of CNV was evaluated. SUBJECTS AND METHODS: Fifteen eyes with AMD that underwent removal of juxtafoveal CNV and extrafoveal CNV near the fovea and had been followed for over one year were included in this study. Eligibility criteria were preoperative visual acuity of 0.3 or less and evidence of CNV activity by fundus angiography. RESULTS: Visual acuity of 0.4 or more was obtained in 60% of the eyes with best visual acuity and 47% with final visual acuity. The mean best visual acuity was 0.51 in cases with Gass type 2, 0.51 in type 1 + 2 CNV, and 0.21 in type 1 CNV. Good post-operative visual acuity was obtained in type 2 and 1 + 2 cases with type 2 CNV at the foveal side accompanied by preoperative foveal retinal sensitivity of 25 dB or more. There was little improvement of visual acuity in type 1 CNV because the retinal pigmented epithelium defect occurred at the fovea. CONCLUSION: For juxtafoveal CNV and extrafoveal CNV near the fovea in AMD, type 2 and 1 + 2 cases with type 2 CNV at the foveal side are thought to be candidates for surgery. Especially, relatively good postoperative visual acuity was obtained in cases with preoperative foveal retinal sensitivity of 25 dB or above. Active surgical removal is thought to be indicated for these cases.  相似文献   
138.
Eighteen and twenty-four hours after intraperitoneal administration of D-galactosamine (1g/kg body weight) to rats, the activity of caspase-3-like protease in the liver increased significantly compared with that in the control group given saline. Histological examinations including the in situ terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method found apoptotic hepatocytes 18 hr after the administration of D-galactosamine. Caspase-3 activity was barely detectable in the plasma of control rats, but increased significantly 24 hr after drug administration along with a dramatic increase in glutamate-oxaloacetate transaminase (GOT). These results indicated that D-galactosamine causes apoptosis in the liver by activating caspase-3, which is released to the plasma by secondary necrosis. The concentration of lipid hydroperoxides in the liver increased significantly 24 hr after D-galactosamine administration. In contrast, the concentration of vitamin C in the liver decreased significantly 18 and 24 hr after D-galactosamine administration. These results suggest that D-galactosamine induces severe oxidative stress in the liver, leading to extensive necrosis.  相似文献   
139.
OBJECTIVE: The aims of this study were to describe job characteristics for daytime and shift workers in home care services for the elderly and to clarify health care in the work setting, social support, and job satisfaction and possibilities. METHODS: A self-reported questionnaire was given to 433 home care workers, both full time and part time (more than 15 hours), at 35 institutions that provide home care services to residents of Sapporo (return rate; 80.2%). The following issues were investigated: job content (physical care, assistance with housework, and advice), specialty, job satisfaction, possibilities, job training, health care and social support. The results were compared among employed types: full-time and part-time daytime and shift workers using the t-test or the Fisher's test. RESULTS: The participants demonstrated high dissatisfaction with wages, physical uneasiness themselves and limited social support from their supervisors. Especially full-time workers were dissatisfied with the payment, whereas part-time workers complained about insufficient attention to the prevention of lumbago. It was found that part-time daytime workers were given insufficient on-job-training and education for prevention of infection, and that full-time shift workers greatly wished to leave the employment. However, the home care workers were satisfied with their job itself and expected to continue their work. Furthermore, half of the part-time workers hoped to work full time. CONCLUSIONS: Health management and educational training for part-time workers may be necessary to improve the quality of care services and protection of health. Promotion of full time employment and reconsideration of working condition might be necessary to provide sufficient home care services.  相似文献   
140.
BACKGROUND: Sevoflurane is known as a useful and safe anesthetic because of its properties of fast uptake and elimination at the lungs and of no effects on hepatic function. In this study we examined the effect of repeated sevoflurane anesthesia on hepatic function and immunological system. METHODS: Eight patients (ASA, PS 2 or 3) received sevoflurane anesthesia three times in 6 months. Six patients had emergency operation for injuries. Aspirate transaminase (AST), alanine transaminase (ALT) and complements (CH50, C3, C4) were measured prior to anesthesia, and 1, 7 and 14 days after anesthesia. RESULTS: The values of AST and ALT were high prior to anesthesia at the first anesthesia. However, these were of no significant changes. CH50, C3, C4 increased significantly after the first anesthesia. However, there were no significant changes of these complements after the second and the third anesthesia. CONCLUSIONS: Our results suggest that sevoflurane is not likely to provide adverse effects on the liver and to suppress the production of complements accompanied by the surgical stress.  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