全文获取类型
收费全文 | 510363篇 |
免费 | 301387篇 |
国内免费 | 46852篇 |
专业分类
耳鼻咽喉 | 5356篇 |
儿科学 | 9137篇 |
妇产科学 | 3738篇 |
基础医学 | 103077篇 |
口腔科学 | 7531篇 |
临床医学 | 89888篇 |
内科学 | 114925篇 |
皮肤病学 | 7883篇 |
神经病学 | 27124篇 |
特种医学 | 18442篇 |
外科学 | 63755篇 |
综合类 | 128694篇 |
现状与发展 | 73篇 |
一般理论 | 3篇 |
预防医学 | 74265篇 |
眼科学 | 21473篇 |
药学 | 90452篇 |
400篇 | |
中国医学 | 67149篇 |
肿瘤学 | 25237篇 |
出版年
2023年 | 5368篇 |
2022年 | 11475篇 |
2021年 | 13815篇 |
2020年 | 15149篇 |
2019年 | 16298篇 |
2018年 | 17065篇 |
2017年 | 20030篇 |
2016年 | 16814篇 |
2015年 | 21741篇 |
2014年 | 25424篇 |
2013年 | 28972篇 |
2012年 | 36958篇 |
2011年 | 40002篇 |
2010年 | 40862篇 |
2009年 | 46886篇 |
2008年 | 34775篇 |
2007年 | 30149篇 |
2006年 | 27405篇 |
2005年 | 23477篇 |
2004年 | 20265篇 |
2003年 | 17588篇 |
2002年 | 15815篇 |
2001年 | 17319篇 |
2000年 | 11583篇 |
1999年 | 13714篇 |
1998年 | 13950篇 |
1997年 | 13802篇 |
1996年 | 14898篇 |
1995年 | 15103篇 |
1994年 | 14842篇 |
1993年 | 13563篇 |
1992年 | 12766篇 |
1991年 | 12131篇 |
1990年 | 11122篇 |
1989年 | 10970篇 |
1988年 | 10538篇 |
1987年 | 9874篇 |
1986年 | 9393篇 |
1985年 | 8460篇 |
1984年 | 6535篇 |
1983年 | 6548篇 |
1982年 | 7606篇 |
1981年 | 7141篇 |
1980年 | 6810篇 |
1979年 | 6642篇 |
1978年 | 5818篇 |
1977年 | 6126篇 |
1976年 | 5746篇 |
1975年 | 5483篇 |
1974年 | 5034篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Factors influencing family physicians to enter rural practice: Does rural or urban background make a difference? 下载免费PDF全文
992.
We found multimolecular antigenic mimicry of arthritogenic autoantigens and peptides from several other “self” or foreign antigens sharing amino acid sequence homologies. Many of these new mimotopes induced arthritis and/or uveitis upon immunization in Lewis rats, indicating a role for multiple antigens in the initiation of a certain autoimmune disease. 相似文献
993.
Thetherapeuticeffectofacupuncturefordia betesmellitus(DM)hasbeenconfirmedbyalarge numberofclinicalinvestigations.Itisasubjectfor acupuncturiststoconsiderandsearchforatherapy providingbettertherapeuticeffectsbywayofproper differentiationofsyndromesandcombinationofacu points.Basedonclinicalexperiencegainedformore than30years,theauthorsofthepresentpaperhave graduallyformedaneffectivecombinedtherapyfor treatingtypeⅡDM(noninsulindependentDM)and itsvariouscomplications.Thereportisasfollows.1CLI… 相似文献
994.
The diurnal variation (DV) in peak expiratory flow rate (PEFR) has been studied among 132 grain elevator workers who accomplished three daily measurements of PEFR during three weeks. DV was calculated as the difference between the highest and the lowest PEFR as a percentage of the mean PEFR on each day. For the whole group the median was 5.9%. DV was higher among smokers and among workers with work related pulmonary symptoms. Analysis of variance showed that only age (p = 0.012) and smoking (p = 0.016) had a significant effect on DV. Pulmonary symptoms, total IgE, and duration of occupation had no independent impact on DV, whereas the exposure level of grain dust tended (p = 0.082) to have an independent effect. Twelve workers had an abnormally high DV (greater than 20%), of whom seven showed no signs of obstructive respiratory disease by spirometry. If only a single spirometric test had been performed the tentative diagnosis of bronchial asthma could have been missed in these seven workers. 相似文献
995.
996.
Cytoskeletal association of human alpha-interferon-receptor complexes in interferon-sensitive and -resistant lymphoblastoid cells. 总被引:6,自引:2,他引:4 下载免费PDF全文
L M Pfeffer N Stebbing D B Donner 《Proceedings of the National Academy of Sciences of the United States of America》1987,84(10):3249-3253
Human Daudi lymphoblastoid cells, which are highly sensitive to the antiproliferative action of human leukocyte alpha-interferon (IFN-alpha), and IFN-resistant and IFN-sensitive Daudi subclones (Cl2 and Cl1, respectively), contain 2300 (Kd = 20 X 10(-12) M), 3000 (Kd = 45 X 10(-12) M), and 3700 (Kd = 52 X 10(-12) M) IFN-alpha binding sites per cell, respectively. Thus, these IFN-sensitive and IFN-resistant cells have similar numbers of high-affinity IFN-alpha receptors. IFN-receptor complexes that are insoluble in Triton X-100 accumulate in IFN-sensitive but not in IFN-resistant cells. The ligand-induced accumulation of Triton-insoluble complexes in IFN-sensitive cells was inhibited by cytochalasin B. This suggests that the solubility change of IFN-receptor complexes results from their interaction with the cytoskeletal matrix. The dissociation of IFN-alpha from IFN-sensitive and IFN-resistant cells can be resolved into fast and slow components. IFN-alpha dissociates more slowly from IFN-sensitive cells than from IFN-resistant cells. Very slow dissociation of IFN-alpha from Triton-insoluble complexes correlates with this difference. These observations suggest that IFN-receptor complexes become coupled to the cytoskeletal matrix in IFN-sensitive but not in IFN-resistant cells, and that such interaction is an important element in the mechanism of the antiproliferative action of IFN-alpha on Daudi cells. 相似文献
997.
Structure of the reaction center from Rhodobacter sphaeroides R-26: the cofactors. 总被引:33,自引:25,他引:8 下载免费PDF全文
J P Allen G Feher T O Yeates H Komiya D C Rees 《Proceedings of the National Academy of Sciences of the United States of America》1987,84(16):5730-5734
The three-dimensional structure of the cofactors of the reaction center of Rhodobacter sphaeroides R-26 has been determined by x-ray diffraction and refined at a resolution of 2.8 A with an R value of 26%. The main features of the structure are similar to the ones determined for Rhodopseudomonas viridis [Michel, H., Epp, O. & Deisenhofer, J. (1986) EMBO J. 5, 2445-2451]. The cofactors are arranged along two branches, which are approximately related to each other by a 2-fold symmetry axis. The structure is well suited to produce light-induced charge separation across the membrane. Most of the structural features predicted from physical and biochemical measurements are confirmed by the x-ray structure. 相似文献
998.
We reviewed all 341 cases of abdominal tuberculosis reported in Canada between 1970 and 1981. Over the study period abdominal tuberculosis accounted for a stable proportion (0.8%) of all reported cases of tuberculosis in Canada. Its incidence declined steadily. It was more common in women, in native Indians and in people born in Asia. Detailed records of the 55 cases reported to Statistics Canada from British Columbia and of an additional 31 cases not reported to Statistics Canada (usually because they involved concomitant disease elsewhere, notably the lungs) were studied. Five of the 55 cases reported to Statistics Canada had been reported incorrectly. Of the 81 cases in British Columbia 51% involved peritonitis, 21% ileocecal disease, 20% anorectal disease, 10% mesenteric lymphadenitis, 1% disease of the sigmoid colon and 1% disease of the liver. The rate of bacteriologic confirmation was low (51%). 相似文献
999.
Sudden coronary death in Glasgow: the severity and distribution of chronic coronary atherosclerotic stenoses. 下载免费PDF全文
A detailed analysis of the extent of coronary artery atherosclerosis was made in 92 white subjects (66 men and 26 women) who died suddenly from ischaemic heart disease. Stenoses resulting in loss of greater than or equal to 75% of luminal cross sectional area (significant stenosis) were found in 90 subjects and these were more extensive in the proximal coronary tree than in the distal. Thirty nine per cent had triple vessel disease, 37% had double vessel disease, and 23% had single vessel disease. In addition one man had an isolated significant stenosis affecting the left main coronary artery. The frequency of significant stenoses in the left main coronary artery was greater in men than in women. The arteries that were least affected were the distal branches of the right coronary artery. A notable feature was the widespread nature of the coronary atherosclerosis: only 26 of the total of 1840 segments of coronary artery examined in the 92 victims could be described as having a normal intima (less than or equal to 10% loss of the area within the internal elastic lamina). 相似文献
1000.
Radiation-induced gastrointestinal fistulae. 总被引:2,自引:0,他引:2
Seventy patients with radiation enteritis presented to a single surgical unit between 1958 and 1984. Of these 10 (14%) had 14 radiation-induced fistulae. The median latent period between radiotherapy and presentation of the fistula was 20 months. The fistulae were often multiple and/or associated with other radiation-induced lesions, patients presenting with fistulae being significantly more likely to have synchronous lesions compared with those who presented with strictures (P = 0.005). These patients are often unfit for major surgery. Wide resection and anastomosis, or exclusion operations are the surgical procedures of choice. 相似文献