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   17095篇
  免费   1060篇
  国内免费   58篇
耳鼻咽喉   335篇
儿科学   397篇
妇产科学   597篇
基础医学   2756篇
口腔科学   375篇
临床医学   2240篇
内科学   2709篇
皮肤病学   449篇
神经病学   1624篇
特种医学   1062篇
外科学   2125篇
综合类   165篇
一般理论   2篇
预防医学   864篇
眼科学   535篇
药学   1082篇
中国医学   19篇
肿瘤学   877篇
  2023年   84篇
  2022年   97篇
  2021年   177篇
  2020年   144篇
  2019年   206篇
  2018年   303篇
  2017年   279篇
  2016年   375篇
  2015年   400篇
  2014年   457篇
  2013年   549篇
  2012年   887篇
  2011年   841篇
  2010年   611篇
  2009年   609篇
  2008年   733篇
  2007年   844篇
  2006年   883篇
  2005年   885篇
  2004年   819篇
  2003年   735篇
  2002年   772篇
  2001年   368篇
  2000年   282篇
  1999年   320篇
  1998年   304篇
  1997年   283篇
  1996年   259篇
  1995年   222篇
  1994年   172篇
  1993年   152篇
  1992年   159篇
  1991年   174篇
  1990年   161篇
  1989年   187篇
  1988年   187篇
  1987年   137篇
  1986年   131篇
  1985年   153篇
  1984年   131篇
  1983年   97篇
  1982年   90篇
  1981年   98篇
  1980年   85篇
  1979年   114篇
  1978年   98篇
  1977年   103篇
  1976年   90篇
  1975年   91篇
  1972年   83篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
At the Fachhochschule Hamburg, a new curriculum on ‘nursing and health’ will be started in summer 1996. This paper informs about ‘health’ in the new curriculum, and the intended emphasis on epidemiology and health promotion. Then the present state of health science instruction in Germany is characterized, and the historical development of interest in this subject. Finally, the short- and long-term need for public health professionals for the north-western part of Germany is estimated.  相似文献   
22.
The distribution of 12 different binding sites for acetylcholine, L-glutamate, GABA, 5-hydroxytryptamine, dopamine and noradrenaline was measured with quantitative receptor autoradiography in four regions of the rat basal forebrain (medial septal nucleus including vertical and horizontal limbs of the diagonal band of Broca, magnocellular preoptic nucleus, substantia innominata and basal nucleus of Meynert, ventral pallidum). L-Glutamate binding sites represent the largest portion of the analysed receptors in all regions, followed by muscarinic2, 5-hydroxytryptamine1 and GABAA receptors. Muscarinic1, dopamine1, dopamine2 and 5-hydroxytryptamine2 receptors and alpha 1-, alpha 1A- and alpha 1B-adrenoceptors represent the minor receptor populations. The largest portion of the dopamine receptors is represented by the dopamine1 subtype, and the alpha 1B subtype dominates the alpha 1-adrenoceptor group. A heterogeneity of the distribution patterns of the different receptors throughout the basal forebrain regions is found. A comparison of the patterns shows that alpha 1-adrenoceptors have a similar regional distribution to that of the muscarinic2 receptors, but both receptor types have reciprocal distributions compared with the 5-hydroxytryptamine1 receptors. The results indicate that one transmitter may exert different effects in the basal forebrain regions depending on the densities of the respective receptor subtypes. Moreover, similar or reciprocal distribution patterns of some, but not all, analysed receptors point to a non-random association (co-distribution) of the different transmitter systems in the basal forebrain regions.  相似文献   
23.
In dry etching processes--one of the sources of potential exposure to toxic wastes in the semiconductor industry--complex mixtures of inorganic and organic compounds arise from reactions between feed stock gases (BCl3/Cl2), top layers (aluminium photoresist), and the carrier gas (N2). Two different fractions of the complex mixture--one an ethanolic solution (ES) and the other an insoluble liquid residue (LR)--were examined for acute oral toxicity in rats. Analytical data showed that the ethanol soluble fraction contained mainly inorganic compounds, whereas the residue contained various halogenated hydrocarbons. Neither death nor behavioral changes occurred after oral administration and observation up to 23 days. ES caused a lower mean arterial blood pressure in both sexes, increased P-R-intervals in male rats, and caused some mild biochemical and hematological alterations and changes in relative organ weights compared to the control groups. Exposure to LR influenced food and water intake, and caused a significant decrease in body weights, signs of polyurie, as well as changes in various relative organ weights and biochemical and hematological parameters. The blood pressure of the male animals fell and the heart rates of both sexes decreased.  相似文献   
24.
Of all the neoplastic conditions of the lymphatic system, Non-Hodgkin's lymphoma (NHL) represents a heterogenous group. As well as lymph nodes NHL can involve extranodal sites, including regions in head and neck. The mouth and oropharynx are typical extranodal sites, and the ENT surgeon should be aware of this possibility of the swift diagnosis of NHL is to be made. We report two patients with rare invasion of the middle ear, facial nerve paresis, and asymptomatic cerebral involvement by Non-Hodgkin's lymphoma.  相似文献   
25.
挪威是一个实行市场经济的国家,我们选择了这样的体系是因为它能够有效地解决很多——但不是全部——生产、货物流通以及服务的竞争问题。在发展一个国际化的市场体系的同时,挪威也发展了强大的公共机构和公共服务。一个有效的市场并不意味着我们就不需要公共部门,或者像有些流行观念所认为的,任何公共服务都应该私有化。其实,一个市场是需要严格的监管,需要与公共组织相配合才能良好地运转,而且需要一个广泛覆盖并且有效的公共部门,来补充提供那些市场无法有效而让人满意地提供的服务,比如教育、医疗和环境保护等。但是,这些公共服务不能由…  相似文献   
26.
AIM: The aim of this study was to investigate the nature and organization of maternal needs and priorities in a neonatal unit. BACKGROUND: The relationship between maternal needs and priorities appears to be an under studied area in neonatal nursing. METHODS: A quantitative survey was carried out based on 209 mothers with premature infants. Two self-assessment schedules were used: critical care maternal needs inventory (J. Leske, Heart and Lung 15, 27-42) and a ranking scale. The data were analysed with multivariate analysis. FINDINGS: Data analysis revealed clear priorities in maternal needs. In particular the need for accurate infant related information was a priority for 93% of the mothers. Good communication practices with professionals were also valued. The mothers displayed altruistic behaviour, and self-related needs took second place. It is proposed that maternal needs demonstrate a hierarchical organization. CONCLUSION: It is important for nurses to consider the individual needs of the mothers, simply because the satisfaction of these needs is essential for maternal well-being.  相似文献   
27.
In patients with mesiotemporal sclerosis, posterior hippocampal involvement at the ictal onset is not associated with an excellent outcome. A study confirmed that ictal onset in the posterior parahippocampal gyrus is associated with a less favorable outcome compared with ictal onset in the anterior parahippocampal gyrus in patients with mesiobasal temporal lobe epilepsy who are undergoing foramen ovale recording. The authors hypothesized that involvement of the two medial contact points of posterior basal temporal subdural (SD) strip at the ictal onset, representing ictal onset in the posterior parahippocampal gyrus, may also adversely influence the surgical outcome. With this objective, the authors assessed the incidence of posterior basal temporal SD strip (the two medial contact points) involvement at the ictal onset in patients with mesiotemporal sclerosis and determined whether presence of this finding influenced surgical outcome. Thirty-six patients with mesiotemporal sclerosis underwent a single SD grid (lateral frontotemporal) and strips (three basal temporal and one orbitosubfrontal) monitoring. Based on the earliest involvement of basal temporal strips (the two medial contact points) during the seizure, patients were classified into (1) anterior and/or middle basal temporal, or (2) posterior basal temporal (with or without involvement of anterior and/or middle basal temporal) ictal onset groups. A temporal lobectomy with adequate resection of the ictal onset zone was performed in all patients. Surgical outcome was based on Engel's classification. Six of 36 (17%) patients were classified into the posterior basal temporal ictal onset group. Only two patients from the posterior basal temporal ictal onset group experienced a good outcome compared with 26 of 30 patients from anterior and/or middle basal temporal ictal onset group (P = 0.01). In patients with mesiotemporal sclerosis who were monitored with SD electrodes, involvement of the two medial contact points of posterior basal temporal strip at the ictal onset (representing ictal onset in the posterior parahippocampal gyrus) occurred in 17% of the patients. These patients might not experience an excellent surgical outcome despite including the ictal onset zone in resection. These findings may be useful in presurgical counseling of patients with mesiotemporal sclerosis who undergo intracranial SD monitoring.  相似文献   
28.
Addition of Nucleophiles to 5-Deazaflavins, Part 1 The reactivity of 5-deazaflavins and 5-deazaflaviniumsalts againts nucleophiles such as hydride-, dithionite-, sulfite- and cyanide ions as well as carbanions is described. The addition takes place in the 5-position and is in much cases reversible with acid. The title-compounds behave, as shown in photoreactions5), as “flavin-shaped nicotinamide models”. Side reactions and reoxidation of the adducts are discussed.  相似文献   
29.
30.
The aim of the present study was to explore cell biological characteristics of normal breast, benign proliferative breast diseases and noninvasive breast malignancies based on the recently published adult progenitor cell concept from our group. Here, we investigated the proliferative activity of CK5/14(+), CK8/18/19(+) and alpha-smooth muscle actin(+) cellular phenotypes encountered in normal mammary gland, in a series of usual ductal hyperplasias and early malignant breast diseases, such as atypical ductal and lobular hyperplasias, as well as ductal and lobular in situ carcinomas. Immunohistochemical double labeling was performed on frozen sections from diagnostic breast biopsies by using antibodies to basal cytokeratins (CK5/14), glandular cytokeratins (CK8/18/19), smooth muscle actin and the Ki-67 antigen (MIB1). Normal breast tissues and usual ductal hyperplasias were characterized by a heterogeneous cellular composition of the growth fraction. The proliferative cell compartment consisted of CK8/18/19(+) glandular and, in a variable proportion, CK5/14(+) progenitor phenotypes. In contrast, noninvasive breast malignancies were composed of a monotonous proliferation of CK 8/18/19(+) neoplastic glandular cells. These findings indicate a significant role of progenitor cells in the development of benign proliferative breast diseases and lend support to the view that malignant transformation in the human breast usually occurs in a cell committed to the glandular lineage. Our results provide cell kinetic support to the functional progenitor cell hypothesis, and we propose this concept as an operative model for understanding benign proliferative and malignant breast diseases.  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