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   7511篇
  免费   314篇
  国内免费   37篇
耳鼻咽喉   46篇
儿科学   149篇
妇产科学   130篇
基础医学   878篇
口腔科学   159篇
临床医学   466篇
内科学   1840篇
皮肤病学   176篇
神经病学   945篇
特种医学   224篇
外科学   1234篇
综合类   27篇
一般理论   1篇
预防医学   230篇
眼科学   177篇
药学   393篇
中国医学   18篇
肿瘤学   769篇
  2023年   44篇
  2022年   91篇
  2021年   156篇
  2020年   84篇
  2019年   130篇
  2018年   167篇
  2017年   114篇
  2016年   121篇
  2015年   130篇
  2014年   194篇
  2013年   226篇
  2012年   373篇
  2011年   380篇
  2010年   202篇
  2009年   178篇
  2008年   313篇
  2007年   341篇
  2006年   325篇
  2005年   341篇
  2004年   272篇
  2003年   271篇
  2002年   254篇
  2001年   232篇
  2000年   244篇
  1999年   191篇
  1998年   83篇
  1997年   68篇
  1996年   45篇
  1995年   51篇
  1994年   52篇
  1992年   178篇
  1991年   169篇
  1990年   151篇
  1989年   168篇
  1988年   152篇
  1987年   121篇
  1986年   111篇
  1985年   129篇
  1984年   100篇
  1983年   81篇
  1979年   75篇
  1977年   44篇
  1976年   45篇
  1974年   47篇
  1973年   57篇
  1972年   53篇
  1970年   55篇
  1969年   53篇
  1968年   47篇
  1966年   42篇
排序方式: 共有7862条查询结果,搜索用时 15 毫秒
991.
Abstract The aim of this study was to investigate the epidemiology of oral mucosal lesions in a selected Cambodian population to obtain pilot data useful in planning an oral health data base for the country. Due to unstable conditions in Cambodia, the validity of population data related to present census information is highly questionable. Therefore, prior to this investigation a census registration was carried out using local health workers as registrars in nine villages of a commune. In the period July 4–31, 1991, a total of 1319 individuals (953 women, 366 men, 15–99 yr) were examined by one oral surgeon in the nine villages of Kok Trop Commune. Kandal Stung District, southwest of the capital Phnom Penh. Clinical diagnoses were based on WHO criteria. Information on smoking habits, betel nut chewing habits, and alcohol use was collected by 4 Khmer dental personnel. In total, 71 lesions were recorded in 64 (4.9%) individuals. Leukoplakia was found in 1.1%, lichen lesions in 1.8%, candidosis in 1.4%, submucous fibrosis in 0.2%, cancer in 0.1%) and other diagnoses in 0.8%. The prevalence of leukoplakia was 2.2% and 0.6% among men and women respectively, a statistically significant difference (P < 0.05). There were significantly more smokers (P < 0.01) among subjects with leukoplakia (64.3%) than among those without this lesion (28.6%). All subjects with lichen lesions were women. The age-adjusted relative risk for developing lichen among betel nut chewers as compared to non-chewers was 3.3. This study has provided information on epidemiological aspects of oral mucosal lesions, including the relationship to etiological factors such as tobacco smoking and betel nut chewing, which might prove valuable in planning future oral health studies and implementing preventive programmes in Cambodia.  相似文献   
992.
We describe herein the results of performing a new technique of low anterior resection of the rectum using a PDS endoloop, on ten patients with rectal cancer. This technique involves first preparing the rectosigmoid colon with an anvil as in the conventional low anterior resection; then, after the stapler is inserted transanally, two endoloops are slid over the colon and rectum. The rectum is ligated by pushing the knot of the endoloop and a second knot is applied 2 cm proximal to the first. Finally, the rectum is cut and the stapler is closed and fired to make a circular end-to-end anastomosis. The level of the anastomosis ranged from 2.5 to 6 cm with a mean of 4.7 cm in the ten patients, only one of whom developed a minor anastomotic leakage postoperatively. Moreover, no patient has developed local recurrence or distant metastasis to date. In summary, this technique offers certain advantages that allow the operation to be done with more skill and safety in a narrow pelvis.  相似文献   
993.
We report a 68-year-old woman who developed progressive dementia and parkinsonism. She was well until 1990 when she was 58 years of age. She started to show memory loss. Four years later, she developed difficulty in dressing and behavioral problems such as eating rice with her hands, going out of her house without purposes, and difficulty in finding the rest room in her house. She was admitted to the neurology service of Hatsuishi Hospital on January 19, 1996, when she was 64 years of the age. On admission, she was alert but markedly demented. The score of Hansegawa Dementia Scale was 0/30. She was unable to make any coherent conversation. She appeared to have dressing apraxia but did not appear to have aphasia. Cranial nerves were intact. She walked in small steps with stooped posture. She did not have motor weakness but she showed plastic rigidity in all four limbs. No tremor or ataxia was noted. Deep tendon reflexes were within normal limits but the plantar response was extensor bilaterally. She continued to deteriorate after admission. In May of 1998, she started to fall. In June of 1998, she had a generalized convulsion. In January of 1999, she became unable to take foods orally and a gastrostomy was placed. She expired on May 29, 1990. She was discussed in a neurological CPC and the chief discussant arrived at the conclusion that the patient had Alzheimer's disease. The question was whether her parkinsonism was a part of her Alzheimer's disease or she had an additional disease to explain her parkinsonism. Post-mortem examination revealed moderate to marked atrophy of the frontal and the temporal lobes as well as in the limbic areas with dilatation of the lateral ventricles. Marked neuronal loss was noted in the CA 1 to the subiculum region with gliosis. Neurofibrillary tangles were seen in the remaining neurons. Neuropil threads were seen by Gallyas-Braak staining. Similar changes were seen in the parahippocampal gyrus and in the entorhinal cortex. Senile plaques were seen in the insular cortex and in other cortical areas. Cortical type Lewy bodies were seen in the cingulate cortex. The Meynert nucleus showed marked neuronal loss and gliosis. The substantia nigra and the locus coeruleus showed moderate loss of pigmented neurons. Lewy bodies were seen in these regions. The dorsal motor nucleus of the vagal nerve was retained, however, one Lewy body was observed. Pathologic diagnosis was Alzheimer's disease plus Parkinson's disease. It is an interesting question whether or not her parkinsonism was due to nigral lesion or frontal lesions. It is known that parkinsonism may complicate in advanced Alzheimer's disease not necessarily due to nigral lesion. On the other hand, in incidental Lewy body disease, the substantia nigra shows mild Parkinson's disease-like change without clinical parkinsonism. This patient appeared to have been a true complication of Alzheimer's disease and Parkinson's disease.  相似文献   
994.
Two cases of vertical gaze nystagmus, which were influenced by posture are reported. In both cases, upbeat nystagmus (UBN) on forward gaze in upright and supine positions changed to downbeat nystagmus (DBN) in prone position. Convergence had no influence on the vertical nystagmus. A CT scan revealed an atrophy of the anterior vermis of the cerebellum in the first case. The UBN of the second case was suspected to be associated with lesions in the brachium conjunctivum. The authors concluded that both UBN and DBN were not completely separate, but they could coexist in cases with certain lesions in the posterior cranial fossa.  相似文献   
995.
Thermotolerance under chronic exposure to moderate hyperthermia at 41 degrees C was hardly induced in the mouse temperature-sensitive mutant ts85 cells, in contrast to the parental wild-type FM3A cells. Thermotolerance was induced at a reduced level in the mutant cells compared with the wild-type cells by incubation at 33 degrees C (permissive temperature), but not at 39 degrees C (non-permissive temperature), after a brief exposure at 44 degrees C. Under conditions where protein synthesis was inhibited by cycloheximide at 41 degrees C, significant amounts of thermotolerance developed in FM3A cells. FM3A cells depleted of cellular ATP by treatment with 2.4-dinitrophenol and 2-deoxyglucose were not sensitized to thermal cell killing at 44 degrees C, when drug-treated cells were washed and exposed to hyperthermia in drug-free growth medium, where cellular ATP rapidly recovered. However, the cells deprived of ATP under the treatment at 41 degrees C failed to develop thermotolerance, indicating a requirement of ATP for thermotolerance development. The decay of thermotolerance was not affected by ATP levels after it was developed. The degradation of abnormal cellular proteins which contained amino acid analogues was promoted at 33 degrees C relative to normal protein degradation in FM3A and ts85 cells. Both normal and abnormal proteins were degraded at a reduced rate at 43 degrees C. Pretreatment of cells at 41 degrees C decreased the rate of degradation of abnormal proteins at 33 degrees C by 20% in FM3A cells and by about 100% in ts85 cells. Pretreatment of cells at 41 degrees C increased significantly the conjugation of 125I-labeled ubiquitin to cellular endogenous proteins in extracts of FM3A cells, but decreased the conjugation in extracts of ts85 cells. The data presented here, in conjunction with the observations by others that the ts85 cell is a mutant defective in the ubiquitination of cellular proteins at nonpermissive temperatures, suggest that the ATP-dependent ubiquitination may be crucial for the development of thermotolerance.  相似文献   
996.
997.
998.
Y Sato  R Suzuki  S Mizuno  T Fukazu 《Gan no rinsho》1987,33(14):1821-1826
We have encountered very unique cases which involve identical twin sisters who underwent surgical treatment for a unilateral breast cancer at the same age of 28. Each, after 13 years, developed cancer in the opposite breast. In addition yet another sister, the youngest, had to undergo the same surgical procedure, at the same age that her identical twin sisters had had their first operations. These findings may indicate the existence of factors which decide the age of the malignancy onset, in addition to the existence of a predisposing factor for carcinoma in the genes of breast cancer patients.  相似文献   
999.
When WGA-HRP (wheat germ agglutinin-horseradish peroxidase conjugate) or HRP was injected into the regions around the superior central and/or the dorsal raphe nuclei in the cat, cell bodies of a number of non-pyramidal neurons were labeled in Ammon's horn. Thus the existence of direct projections from non-pyramidal neurons in Ammon's horn to the rostral raphe regions in the brainstem was suggested in the cat.  相似文献   
1000.
Change of urate and ascorbate levels in retinae of rat left eyes after ophthalmic artery and optic nerve ligation was studied by reversed-phase high-performance liquid chromatography with electrochemical detection. The right eyes were used for sham operation. We found that uric acid levels in the retinae of the left eyes increased as a function of time after the operation, whereas those of the right eyes remained unchanged. In addition, we found that ascorbic acid levels in the retinae of the rat eyes decreased after the operation.  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