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   5618篇
  免费   379篇
  国内免费   68篇
耳鼻咽喉   65篇
儿科学   300篇
妇产科学   100篇
基础医学   731篇
口腔科学   182篇
临床医学   617篇
内科学   1256篇
皮肤病学   88篇
神经病学   478篇
特种医学   465篇
外科学   571篇
综合类   101篇
一般理论   10篇
预防医学   383篇
眼科学   97篇
药学   295篇
中国医学   2篇
肿瘤学   324篇
  2021年   47篇
  2019年   39篇
  2018年   61篇
  2017年   52篇
  2016年   69篇
  2015年   61篇
  2014年   115篇
  2013年   167篇
  2012年   203篇
  2011年   230篇
  2010年   131篇
  2009年   116篇
  2008年   175篇
  2007年   265篇
  2006年   250篇
  2005年   209篇
  2004年   220篇
  2003年   210篇
  2002年   191篇
  2001年   169篇
  2000年   208篇
  1999年   155篇
  1998年   83篇
  1997年   79篇
  1996年   78篇
  1995年   96篇
  1994年   59篇
  1993年   73篇
  1992年   163篇
  1991年   157篇
  1990年   170篇
  1989年   172篇
  1988年   141篇
  1987年   131篇
  1986年   135篇
  1985年   127篇
  1984年   103篇
  1983年   89篇
  1982年   51篇
  1981年   44篇
  1980年   48篇
  1979年   80篇
  1978年   56篇
  1976年   49篇
  1975年   42篇
  1974年   45篇
  1973年   56篇
  1972年   52篇
  1971年   41篇
  1970年   40篇
排序方式: 共有6065条查询结果,搜索用时 15 毫秒
51.
The present study documents the characteristics of innervation of the rhinarium or hairless rat snout skin by light and electron microscopy. The outer glabrous surface is covered with a stratified squamous epithelium that forms both rete pegs and rete ridges, the latter on the inferior border near the philtrum. The glabrous skin contains numerous presumptive epidermal and dermal free nerve endings (FNE's), Merkel terminals at the base of the rete ridges and pegs, and simple, nonencapsulated corpuscles. A second region of dense innervation, found on an elevation of the inner wall of the vestibule, contains similar components of innervation, with the exception that no Merkel terminals were identified. Since no Merkel terminals were present in this area of the vestibule, intraepidermal as well as dermal FNE's could be identified with certainty. This skin is covered by a thin squamous epithelium overlying dense connective tissue. The simple corpuscles are similar to those in the rhinarium, as well as resembling those described in other species. FNE's were frequently observed intimately associated with simple corpuscles. Several examples of large FNE's with two to three layers of cytoplasmic lamellae were found, suggestive of transitional forms between FNE's and simple corpuscles. Thus, the pattern of sensory innervation in the glabrous rat snout skin is similar to that found in other furred species described to date, but in addition, the sensory innervation of ridged skin in the rat also resembles that of epidermis organized into rete pegs. This dense sensory innervation may be correlated with whisking behavior of the predominantly nocturnal rat.  相似文献   
52.
The fine needle aspiration cytology of two cases of bronchiolo-alveolar cell carcinoma of the lung having unusual features is reported. One case demonstrated numerous psammoma bodies in the cytologic smears, whereas the other case showed an abundance of cells with optically clear nuclei. Both peripherally located tumors were resected and confirmed as primary bronchiolo-alveolar cell carcinoma by histologic and ultrastructural examination. We believe this to be the first report describing these unusual features of bronchiolo-alveolar cell carcinoma diagnosed by fine needle aspiration cytology. Presented is a discussion of psammoma bodies and optically clear nuclei seen in primary and metastatic tumors of the lung. This will aid in the diagnosis of these cases.  相似文献   
53.
The fine-needle aspiration (FNA) cytology of two cases of granulocytic sarcoma involving the breast is reported along with the FNA cytology of one case of myeloid metaplasia (extramedullary hematopoiesis) involving an axillary lymph node. Two patients had known myeloproliferative disorders, while granulocytic sarcoma of the breast was the initial presentation of an unsuspected acute granulocytic leukemia in the other patient. Diff-Quik-stained preparations aided in the diagnosis of all three cases. Immunoperoxidase stains for factor VIII-related antigen helped confirm the megakaryocytic differentiation of the cells in the FNA cytology of myeloid metaplasia. Electron microscopic (EM) examination performed on the aspirated material also showed megakaryocytic differentiation of the bizarre cells. FNA cytology can make a specific diagnosis of granulocytic sarcoma and myeloid metaplasia. The workup of these unusual extramedullary myeloproliferative masses was aided when immunocytochemistry and EM were performed on the aspirated material.  相似文献   
54.
Characteristics of very poor outcome schizophrenia   总被引:2,自引:0,他引:2  
The authors compared 21 "Kraepelinian" schizophrenic patients who had been ill and dependent on others for the past 5 years with 76 chronic schizophrenic patients in remission or with exacerbations requiring hospitalization. The Kraepelinian patients met the criteria for schizophrenia by more diagnostic systems than the exacerbated patients, were less responsive to haloperidol, had more severe negative symptoms, and had similarly severe positive symptoms. They had cerebral ventricles that were more asymmetrical and a greater family history of schizophrenia spectrum disorders than the other chronic patients. These data suggest that patients with 5 years of illness and complete dependency on others may represent a subgroup of schizophrenia.  相似文献   
55.
Annals of Surgical Oncology - The aim of this study was to report outcomes following percutaneous microwave and cryoablation of lung metastases from adenoid cystic carcinoma (ACC) of the head and...  相似文献   
56.
The only effective measure to decrease morbidity and mortality caused by the influenza virus in the human population is worldwide vaccination. Vaccination produces neutralizing antibodies that target the HA1 subunit of the HA (hemagglutinin) protein and are strain specific. The effectiveness of new influenza vaccines are linked to two factors, the correct prediction of the circulating strains in the population in a particular season and the concentration of the HA1 protein in the vaccine formulation. With the advent of the licensing of quadrivalent vaccines, pharmaceutical manufacturers are under considerable pressure due to time constraints and dedicated resources to deliver 194–198 million doses (2020–2021 U.S. market) of vaccine. Considering the valuable resources needed to produce the influenza vaccine in a timely manner, the efficient quantitation of the HA1 protein (the main component in the influenza vaccine) is required. Currently the only method approved by regulatory agencies for quantitation of the HA antigen in vaccines is the single radial immunodiffusion assay (SRID), an antibody dependent assay that is not time efficient. Time efficient methods that are antibody independent e.g. reverse phase-high performance liquid chromatography (RP-HPLC) or size exclusion-HPLC (SE-HPLC) are available. An improved method implementing reverse phase-ultra performance liquid chromatography (RP-UPLC) has been developed to quantitate the HA1 protein antigen present in the high yield reassortant vaccine seed viruses from influenza A H1N1 and H3N2 subtypes harvested from inoculated embryonated chicken eggs. This method differentiates between high yield and lower yielding reassortants in order to select the best vaccine candidate seed virus with the highest growth ‘in ovo’. This direct capability to monitor the HA1 concentration of potential reassortant seed viruses and to choose the best yielding HA influenza reassortant when faced with multiple viral seed candidates provides a major advantage on the industrial scale to the influenza vaccine process.  相似文献   
57.
Medical records of 81 older patients (65 years of age and over) who underwent electroconvulsive therapy (ECT) at a university-affiliated private geriatric hospital were reviewed to evaluate the safety and efficacy of this treatment for depression in the "young-old" (65 to 80 years) compared with the "old-old" age group (over 80 years), a group that has not yet been adequately studied. Information was obtained regarding demographics, medical and psychiatric diagnosis, medications, indications for ECT, number and laterality of treatments, outcome, and complications. Thirty-nine patients 80+ years of age (mean age, 85 +/- 3.2) were compared with 42 patients 65 to 80 years of age (mean age, 74 +/- 5.2). Statistical analysis was performed using confidence intervals of the difference in proportions of patients in each group. There were no significant differences in the demographics, number and laterality of ECT treatments, indications for ECT treatment, medical diagnosis, medications, or prior history of falls, but psychiatric diagnoses differed slightly. Patients over 80 years had significantly more cardiovascular complications and falls (95% confidence interval) and tended to have a worse ASA (American Society of Anesthesiologists) scale rating and a somewhat less successful outcome. This study confirms the role of ECT as a relatively safe and effective treatment, which may be lifesaving in selected depressed older patients. Prospective studies are needed to understand better the long-term outcome and to prevent the morbidity and mortality associated with ECT in this frail, high-risk older group.  相似文献   
58.
There has been clinical speculation that parents of young stuttering children have expectations of their children's communication abilities that are not well-matched to the children's actual skills. We appraised the language abilities of 15 children close to the onset of stuttering symptoms and 15 age-, sex-, and SES-matched fluent children using an array of standardized tests and spontaneous language sample measures. Parents concurrently completed two parent-report measures of the children's communicative development. Results indicated generally depressed performance on all child speech and language measures by the children who stutter. Parent report was closely attuned to child performance for the stuttering children; parents of nonstuttering children were less accurate in their predictions of children's communicative performance. Implications for clinical advisement to parents of stuttering children are discussed.  相似文献   
59.
Recognition and management of Kawasaki disease   总被引:19,自引:0,他引:19       下载免费PDF全文
Kawasaki disease is the leading cause of acquired heart disease in children in the developed world, with coronary artery aneurysms occurring in up to 25% of untreated cases. The mean annual incidence of Kawasaki disease across Canada is about 13 per 100,000 children less than 5 years of age, based on hospital discharge data from 1990 to 1995. The cause remains unknown, and the diagnosis is based on the same clinical criteria used to describe the disease over 30 years ago. However, nonspecific clinical features, evolving presentations and atypical or incomplete presentations make early diagnosis and timely treatment difficult. Delays in diagnosis and treatment, which occur more frequently in older children, are associated with an increased risk of coronary artery aneurysms. Hence, high diagnostic suspicion and prompt referral are required to reduce the rate of cardiac complications.  相似文献   
60.
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