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   1453132篇
  免费   120070篇
  国内免费   6646篇
耳鼻咽喉   18569篇
儿科学   46549篇
妇产科学   39061篇
基础医学   199333篇
口腔科学   40676篇
临床医学   127967篇
内科学   306756篇
皮肤病学   35475篇
神经病学   119690篇
特种医学   58174篇
外国民族医学   275篇
外科学   224560篇
综合类   32151篇
现状与发展   2篇
一般理论   446篇
预防医学   119412篇
眼科学   30668篇
药学   101547篇
  5篇
中国医学   2762篇
肿瘤学   75770篇
  2019年   11796篇
  2018年   17928篇
  2017年   13327篇
  2016年   15291篇
  2015年   17097篇
  2014年   23237篇
  2013年   34710篇
  2012年   44694篇
  2011年   47889篇
  2010年   28988篇
  2009年   27265篇
  2008年   43631篇
  2007年   46434篇
  2006年   47045篇
  2005年   45498篇
  2004年   42898篇
  2003年   41518篇
  2002年   39261篇
  2001年   69159篇
  2000年   71424篇
  1999年   59334篇
  1998年   17322篇
  1997年   15474篇
  1996年   16478篇
  1995年   16563篇
  1994年   15329篇
  1993年   14417篇
  1992年   48125篇
  1991年   46611篇
  1990年   44739篇
  1989年   42470篇
  1988年   39291篇
  1987年   38621篇
  1986年   36413篇
  1985年   35100篇
  1984年   26699篇
  1983年   22372篇
  1982年   13985篇
  1981年   12577篇
  1980年   11842篇
  1979年   23845篇
  1978年   17250篇
  1977年   14560篇
  1976年   13367篇
  1975年   13966篇
  1974年   16366篇
  1973年   15701篇
  1972年   14430篇
  1971年   13310篇
  1970年   12140篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
In order to clarify the reported discrepancies in S100 alpha protein and mRNA distribution in rat tissues, a rat S100 alpha cDNA has been isolated and this species homologous probe along with a rat S100 beta cDNA probe has been used to examine S100 mRNA expression in rat tissues. Although the rat S100 alpha cDNA was missing approximately 30 nucleotides of coding sequence, only 4 conservative changes in amino acid sequence were observed when the deduced amino acid sequence was compared to the bovine S100 alpha amino acid sequence. Thus, S100 alpha proteins, like S100 beta proteins, are highly conserved among species. All nineteen of the tissues examined (including cerebrum and cerebellum) contained S100 alpha mRNA. In addition, S100 beta mRNA was detected in thirteen of the nineteen tissues examined. These results are in agreement with previous protein distribution studies and further demonstrate that S100 proteins are not brain-specific and are expressed in a large number of tissues. Although S100 alpha and S100 beta mRNAs were detected in rat tissues which had previously been reported to contain S100 alpha and S100 beta protein, a direct correlation between the protein and mRNA levels were not observed, suggesting that different mechanisms regulate S100 expression in various tissues. S100 alpha exhibited a single similar size mRNA species (0.5 Kb) in all tissues examined, as did S100 beta (1.5 Kb), suggesting that the individual S100 proteins are expressed as single mRNA and protein products in rat tissues.  相似文献   
992.
A new surgical technique for the treatment of recurrent temporomandibular joint subluxation or dislocation is described. Following a horizontal osteotomy and down-fracture of the articular eminence an inter-positional bovine cartilage xenograft is inserted in order to augment the vertical height of the eminence. The procedure combines simplicity with minimal post-operative morbidity. The increase in eminence height is both predictable and stable.  相似文献   
993.
Deafness mutant mice show no stimulus-related cochlear potentials as well as abnormal electrically-evoked responses recorded from the inferior colliculus. Abnormal spontaneous activity in the auditory periphery could result in abnormal development and/or maintenance of the central auditory pathways. We therefore assessed spontaneous activity of cochlear origin in the central nuclei of the mutants by ablating one cochlea and subsequently using the 2-deoxyglucose (2DG) technique to study metabolic activity. Any asymmetries in labeling in a given nucleus should be due to spontaneous activity in the cochlear nerve on the unoperated side. In control animals (+/dn mice undergoing unilateral cochlea ablation), statistically significant decreased 2DG labeling was observed in the ipsilateral PVCN and AVCN, and contralateral MNTB and IC; all receive primary excitatory input from the ablated ear. No significant differences in labeling between right and left sides were observed in any of the nuclei studied in the mutant animals. These findings suggest that there is no spontaneous activity of cochlear origin in these mutants, even though many cochlear nerve fibers and spiral ganglion cells survive.  相似文献   
994.
995.
To assess the adequacy of the nutritional care provided, a prospective noninterventional study was carried out on 250 randomly selected patients aged 65 and over who were admitted to a Veterans Administration Hospital. Of this group, 97 patients (39%) were found to be at high risk of having clinically significant protein-energy malnutrition. In 43 cases (17%), an assessment of the patient's nutritional status was not possible because the available data were inadequate. No patient had a diagnosis of malnutrition recorded on the problem list. Only 13 percent of the high-risk patients received some form of nutrition support therapy; 10 (10%) received oral supplements, and four (4%) were started on enteral feedings. Patients who received enteral feedings experienced a high rate of complications resulting from use of the feeding tubes. Over all, none of the high risk study patients received optimal nutrition support therapy. These findings indicate that elderly patients hospitalized in the Veterans Administration hospital in this study are usually not screened appropriately for protein-energy malnutrition, the diagnosis is frequently missed or ignored, and nutrition support therapy is underutilized and often ineffectually managed.  相似文献   
996.
Myelographic study of the spinal cord ascent during fetal development   总被引:2,自引:0,他引:2  
To assess the length of the spinal cord relative to the vertebral column during fetal development, we performed translumbar myelograms on 340 spontaneously aborted fetuses. Of these, 146 were selected for study. There were 76 males and 70 females, with fetal age ranging from 7 to 33 weeks. Significant variation in the level of spinal cord termination was found in fetuses between 12 and 25 weeks gestational age. In fetuses between 25 and 33 weeks gestational age, the cord ended at or above the third lumbar vertebra.  相似文献   
997.
Fine Needle Aspiration Cytology (F.N.A.C.) has been used as a diagnostic tool by the ENT departments in Tayside since the end of 1985. This paper discusses the results of our initial experience with this and outlines some of the diagnostic pitfalls. This is a useful and accurate procedure with many advantages over diagnostic biopsy.  相似文献   
998.
The nerve action potential at the elbow and somatosensory evoked potentials (SEPs) at the scalp were recorded over 30 minutes of tourniquet-induced limb ischaemia in 10 diabetic patients and 10 controls. According to the SEP changes, an increased resistance to nerve ischaemia in diabetic patients was observed. The pathways involved in SEP conduction are discussed.  相似文献   
999.
1000.
Lung cancer is the leading cause of cancer deaths in both men and women in the United States. Treatment depends on the type and stage of lung cancer. For stage I and II cancer, surgery is usually the treatment of choice. Radiation therapy is used in patients who are considered poor risks for surgical resection. Intraoperative brachytherapy is an effective alternative to external irradiation in this group of patients. From 1958 to 1984, 55 patients with non-small-cell lung cancer were explored at Memorial Sloan Kettering Cancer Center and found to have surgical stage I or II tumors, which were considered to be unresectable mainly because of severe obstructive pulmonary disease precluding adequate resection. All these patients were treated with intraoperative brachytherapy at the time of the thoracotomy. Forty-four percent of these patients received in addition external irradiation, mainly to the mediastinum. The overall 5-year survival calculated by the Kaplan-Meier Method was 32%, and the local disease-free survival was 63%. Cox regression multivariant analysis demonstrated that there is a distinct subgroup with a better prognosis based on tumor site and patient's age--ie, patients who were younger than 58 years of age and had right-side lesions.  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