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   42692篇
  免费   2254篇
  国内免费   168篇
耳鼻咽喉   128篇
儿科学   1099篇
妇产科学   605篇
基础医学   2662篇
口腔科学   678篇
临床医学   5673篇
内科学   5451篇
皮肤病学   375篇
神经病学   1507篇
特种医学   462篇
外科学   2114篇
综合类   4538篇
现状与发展   1篇
一般理论   4篇
预防医学   16138篇
眼科学   200篇
药学   2102篇
  19篇
中国医学   533篇
肿瘤学   825篇
  2024年   340篇
  2023年   956篇
  2022年   1768篇
  2021年   2160篇
  2020年   2007篇
  2019年   2886篇
  2018年   2495篇
  2017年   1588篇
  2016年   1064篇
  2015年   1264篇
  2014年   3090篇
  2013年   2878篇
  2012年   2665篇
  2011年   2903篇
  2010年   2244篇
  2009年   2051篇
  2008年   1970篇
  2007年   1849篇
  2006年   1406篇
  2005年   902篇
  2004年   737篇
  2003年   575篇
  2002年   466篇
  2001年   412篇
  2000年   343篇
  1999年   300篇
  1998年   240篇
  1997年   180篇
  1996年   103篇
  1995年   111篇
  1994年   81篇
  1993年   80篇
  1992年   68篇
  1991年   42篇
  1990年   28篇
  1989年   27篇
  1988年   23篇
  1985年   249篇
  1984年   363篇
  1983年   296篇
  1982年   305篇
  1981年   296篇
  1980年   240篇
  1979年   229篇
  1978年   203篇
  1977年   150篇
  1976年   135篇
  1975年   117篇
  1974年   101篇
  1973年   77篇
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
21.
An automated multiphasic-health-test system has been opened in Japan for the early detection and treatment of disease in adults. The centre utilises system simulation, digital computation and automated medical equipment, and has made it possible to handle many examinees daily, and to retrieve their data easily. This paper reports many new data and their analysis.  相似文献   
22.
In recent years, major and widely accepted information security understandings and achievements confirm that the problem is complex. They clarify that technologies are fundamental tools, but management processes have even bigger relevance, as also prestigious international magazines dossier clearly explained recently. Such a magazine attention outlines the wide impact that the subject has on watchful decision makers. ISO17799 is an emerging standard in information security. In principle there are no reasons for considering it not applicable to the health care sector. In practice, because of both the just conceptual level of the standard and the peculiarities of the health care data and institutions, a lot of analysis and design work need to be invested any time a health care institution decides to deal with the subject. CEN/ENV 12924 is another emerging standard certainly more on the spot of the health care. Nevertheless, it also asks for evident further investigation. The practical case of information security design, implementation, management, and auditing inside a multi-specialty provincial Italian hospital will be described.  相似文献   
23.
Distinguishing characteristics of a new neuroblastoma cell line   总被引:3,自引:0,他引:3  
The characteristics of a new neuroblastoma cell line (MC-NB-1) established from the bone marrow of a 2-year-old male are described. Morphologically, the cells appear as flattened and epithelial-like or as small and spherical. Electron microscopy demonstrated microtubules and dense core secretory granules. The doubling time was approximately 35 hr. Isoenzyme patterns and catecholamine secretion indicated a human line of neuronal origin. The soft agar tumor colony forming system demonstrated drug resistance in vitro comparable to in vivo nonresponsiveness. The stemline karyotype of MC-NB-1 is 44,Y,del(1) (p22:), -4, -7, +del(7)(q22:), -16, +t(7;16)(16pter leads to 16q24::7q22 leads to 7q32), -17. Additionally, double-minute bodies were observed. However, no evidence of homogeneous staining regions (HSRs) were detected.  相似文献   
24.
Sixty-six bipolar I lithium clinic patients were studied for a history of psychotic symptoms at some time during the course of their illness. Agreement between different sources of information was calculated, and the patient population was divided into psychotic and non-psychotic subgroups. Probability of remaining well on lithium for the different subgroups was analyzed by the life table method. Psychosis during mania appeared to be associated with especially good early lithium prophylaxis.  相似文献   
25.
The cholinergically innervated human eccrine sweat gland is a readily available organ permitting the assessment in allergic patients of cholinergic reactivity with few or no adrenergic influences. The sweat responses of four matched groups (male allergic, female allergic, male control, and female control) to intradermal Mecholyl from 0.1 μg to 100 μg was compared; the 45 male and 45 female allergic patients demonstrated statistically significant increases in sweat responses to essentially all concentrations of Mecholyl examined. No difference in the sweat responses of patients with allergic rhinitis alone as compared with patients with both allergic rhinitis and allergic asthma was noted. Five patients with intrinsic asthma most closely resembled the allergic groups in their responses and 8 patients with vasomotor rhinitis sweated at or below the control groups. The increased sensitivity of allergic patients to cholinergic stimulation as measured by eccrine sweat responses suggests that this hyperresponsiveness may be one of the underlying defects in allergic disease.  相似文献   
26.
To more nearly accurately quantitate the dose of pharmacologic agents delivered to human and animal airways via aerosols, we have developed a monodisperse aerosol containing either methacholine or histamine that permits a light scattering device (tyndallometry) to measure accurately the quantity of inspired and expired particles. These aerosols (described in previous studies) are simultaneously tagged with a radioactive label (technetium 99m) to permit the use of external gamma camera imaging. Present work focuses on the development of assay techniques to measure the quantity of methacholine delivered in these aerosols. The lack of specific radioimmune or radioenzyme assays coupled with the cross-reaction of organic contaminants with conventional chemical reagents for measuring methacholine required the development of separative techniques to isolate the methacholine from the organic aerosol contaminants. With aqueous extraction and column separation we have been able to completely isolate the methacholine from these contaminants. This allows the application of standard spectrophotometric assays for methacholine to quantitate the methacholine in the resulting solution. These separative techniques will permit the use of these aerosols in quantitative studies of airway reactivity.  相似文献   
27.
Skin tests and in vitro histamine-release reactions were used to evaluate 130 patients observed in an employee allergy clinic at a biomedical research facility. The allergens used included extracts from pollens (ragweed, grasses, trees, weeds), molds, mixed feathers, house dust, cat, dog, mouse, rat, rabbit, guinea pig, and hamster. Of all patients, 66% complained of allergic symptoms on laboratory animal exposure, although only 52% worked directly with animals. Among patients with symptoms, 91% were positive by skin test to at least one laboratory animal, and 46% had asthma. The median length of exposure to laboratory animals before onset of symptoms was 2.8 yr with 60% of the patients developing their symptoms within 3 yr. Among patients who had allergic symptoms before exposure to laboratory animals, 79% were skin test positive to laboratory animals when they were evaluated in this study. There was a close association found between the skin test and histamine-release results with the laboratory animal allergens: 91% of the 4+ skin reactors had leukocytes positive for histamine release versus 5% of the leukocyte donors with less than 1+ skin reactions. A close relationship in positive reactions to different laboratory animal allergens was also found. For example, individuals positive to mouse were positive also to rat (95%), rabbit (79%), guinea pig (83%), and hamster (88%). Patients who reacted to laboratory animals also reacted to some extent to house dust and cat and dog allergens, and about one half of the animal-allergic individuals reacted to pollens. Although nonpollen-allergic individuals can develop sensitivity to laboratory animals, the group at higher risk are allergic individuals, especially those sensitive to house dust, cats, or dogs.  相似文献   
28.
29.
DRw6 has been difficult to define serologically. In the present experiments we have developed T cell lines in order to characterize the components of a DRw6 haplotype. This was accomplished by priming T cells with allogeneic mononuclear cells mismatched for DRw6, Dw6, and MT2. Subsequently, three sublines with distinct reactivity patterns were derived by limiting dilution. The specificities detected by these sublines included: (a) a specificity found on a subset of cells positive for DRw6 which was inhibited by monoclonal antibodies against DS(DC), the human homologue of the murine IA-encoded molecules, (b) another DRw6-associated specificity blocked by an MT2-like antibody, and (c) an MT2-like specificity blocked by monoclonal antibodies reactive with a different MT2-associated determinant. These results show that more than one IE-like, as well as the DS/DC (IA-like) molecules, carry distinctive antigenic epitopes that can be recognized by allogeneic T cells. Primed T cell lines may be useful for a better definition of certain haplotypes which are at present difficult to characterize with serological reagents alone.  相似文献   
30.
The concept of the differential diagnosis has a central place in all clinical medicine. In neurology and paediatrics, evolution of thought concerning the differential diagnosis of the child presenting with symptoms of neuromuscular disease was far in advance of similar diagnostic approaches to problems of infectious, infective and neoplastic disease; and as such forms a significant historical model for the development of modern clinical approaches to the sick or disabled child. The account presented in this paper provides a detailed historical review of the development of thought relating to the causes of neuromuscular disease. Nosological developments concerning diseases of the motor unit can be conveniently classified into three periods: (a) a "state of the art" period to 1850; (b) 1850-1890 - a period of parallel and interdependent advances in both normal neuro-anatomy and neurophysiology, and diseases recognized as variations from such norms. In this era Duchenne was the first to write about the differential diagnosis of the progressive muscular paralysis in childhood; and Gowers was the first to write specifically on the hereditary transmission of this group of diseases; (c) in 1891 was described the first case of childhood neuronopathy recognized as such, and with this development was ushered in the modern era of clinical differential diagnosis of childhood neuromuscular disease. The "splitters" have won the great debate concerning the clinical approach to neurological diseases. The continual further refining of an exact diagnosis is the only way in which a realistic prognosis can be forecast, correct genetic counseling can be offered, and (if the condition is treatable) optimal therapy can be introduced.  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