全文获取类型
收费全文 | 53054篇 |
免费 | 3588篇 |
国内免费 | 181篇 |
专业分类
耳鼻咽喉 | 601篇 |
儿科学 | 1067篇 |
妇产科学 | 792篇 |
基础医学 | 6780篇 |
口腔科学 | 693篇 |
临床医学 | 4895篇 |
内科学 | 12843篇 |
皮肤病学 | 532篇 |
神经病学 | 5188篇 |
特种医学 | 2100篇 |
外科学 | 8471篇 |
综合类 | 587篇 |
一般理论 | 65篇 |
预防医学 | 3656篇 |
眼科学 | 926篇 |
药学 | 3186篇 |
中国医学 | 49篇 |
肿瘤学 | 4392篇 |
出版年
2024年 | 42篇 |
2023年 | 286篇 |
2022年 | 601篇 |
2021年 | 1435篇 |
2020年 | 900篇 |
2019年 | 1294篇 |
2018年 | 1641篇 |
2017年 | 1118篇 |
2016年 | 1204篇 |
2015年 | 1440篇 |
2014年 | 2162篇 |
2013年 | 2510篇 |
2012年 | 4324篇 |
2011年 | 4290篇 |
2010年 | 2401篇 |
2009年 | 2148篇 |
2008年 | 3754篇 |
2007年 | 3864篇 |
2006年 | 3739篇 |
2005年 | 3682篇 |
2004年 | 3283篇 |
2003年 | 3025篇 |
2002年 | 2736篇 |
2001年 | 315篇 |
2000年 | 220篇 |
1999年 | 325篇 |
1998年 | 487篇 |
1997年 | 439篇 |
1996年 | 356篇 |
1995年 | 324篇 |
1994年 | 251篇 |
1993年 | 236篇 |
1992年 | 142篇 |
1991年 | 126篇 |
1990年 | 113篇 |
1989年 | 95篇 |
1988年 | 87篇 |
1987年 | 68篇 |
1986年 | 75篇 |
1985年 | 100篇 |
1984年 | 121篇 |
1983年 | 105篇 |
1982年 | 136篇 |
1981年 | 109篇 |
1980年 | 95篇 |
1979年 | 42篇 |
1978年 | 60篇 |
1977年 | 57篇 |
1976年 | 49篇 |
1975年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
53.
Mary E. Van Bourgondien Lee M. Marcus Eric Schopler 《Journal of autism and developmental disorders》1992,22(4):493-506
The purpose of this study was to clarify the issue of whether DSM-III-R (American Psychological Association [APA], 1987) over-or underdiagnoses autism by comparing this diagnostic system to a well-established objective measure of diagnosis, the Childhood Autism Rating Scale (CARS). A secondary goal was to determine which of the 16 criteria are the best discriminators of autism. DSM-III-R, CARS, and clinical diagnoses of 138 consecutive admissions to a statewide program for the diagnosis and treatment of autistic and related communication-handicapped individuals (Division TEACCH in North Carolina) were compared. Results indicated a generally high degree of agreement on the diagnosis of autism using the three systems. Within this tratment-oriented program, the CARS and clinical ratings diagnosed a greater number of cases as autistic than did the DSM-III-R criteria, suggesting that DSM-III-R slightly underdiagnosed autism. The criteria that most strongly related to the diagnosis of autism regardless of the system were lack of awareness of others, abnormal social play, an impaired ability to make friends, abnormal nonverbal communication, stereotypic body movements, and restricted range of interests. 相似文献
54.
The spinal cord dorsal horn contains neural mechanisms which can greatly facilitate pain. We have recently shown that ‘illness’-inducing agents, such as intraperitoneally administered lipopolysaccharide (LPS; bacterial endotoxin), can produce prolonged hyperalgesia. This hyperalgesic state is mediated at the level of the spinal cord via activation of the NMDA-nitric oxide cascade. However, prolonged neuronal depolarization is required before such a cascade can occur. The present series of experiments were aimed at identifying spinal neurotransmitters which might be responsible for creating such a depolarized state. These studies show that LPS hyperalgesia is mediated at the level of the spinal cord by substance P, cholecystokinin and excitatory amino acids acting at non-NMDA sites. No apparent role for serotonin or kappa opiate receptors was found. 相似文献
55.
56.
57.
58.
E. Eric Muirhead David H. P. Streeten Bennie Brooks Edward T. Schroeder Lawrence W. Byers 《Blood pressure》1992,1(3):138-148
A new syndrome is described in a patient with advanced renal insufficiency. This consists of severe and persistent hypotension causing weakness but associated with a clear mental status. Also present is evidence for decreased vascular reactivity. The hypotension was not orthostatic. The hypotension was associated with a circulating vasodepressor substance having the characteristics of medullipin I. The medullipin appears to have been derived from the remaining right kidney. Hypotension existed despite the presence of major prohypertensive mechanisms, including an endstage kidney, hyperreninemia and hyperaldosteronemia. It is likely that hypotension due to hypermedullipinemia is an entity occurring in the human being. 相似文献
59.
60.
Michael Bliziotes Jean D Sibonga Russell T Turner Eric Orwoll 《Journal of bone and mineral research》2006,21(7):1060-1067
Periosteal bone turnover is poorly understood. We documented intramembranous periosteal bone turnover in the femoral neck in intact nonhuman primates and an increase in osteoclast numbers at the periosteal surface in sex steroid-deficient animals. Our studies are the first to systematically document periosteal turnover at the femoral neck. INTRODUCTION: Bone size is an important determinant of bone strength, and cellular events at the periosteal surface could alter bone dimensions. We characterized periosteal cellular activity with dynamic histomorphometric studies of nonhuman primate femoral neck and shaft. MATERIALS AND METHODS: Femur specimens from 16 intact adult male and female nonhuman primates (Rhesus [Macaca mulatta, n = 9] and Japanese Macaque [Macaca fuscata, n = 7]) were analyzed. Animals were double-labeled with tetracycline, and necropsy was performed 2-7 days after the last dose. We characterized periosteal resorptive activity in an additional group of five intact and four castrate female animals. Multiple group comparisons in intact animals were performed by one-way ANOVA followed by a Fisher PLSD posthoc test. In gonadectomized animals, Fisher's exact test was used for dichotomous and Mann-Whitney U-test for continuous variables. RESULTS: Bone turnover in the periosteum of the femoral neck in intact animals was more rapid than at the femoral shaft but slower than in femoral neck cancellous bone. Similarly, in these intact animals, the eroded surface of cortical bone at the femoral neck periosteal surface was significantly greater than in the cancellous bone compartment (p < 0.0001) or on the femoral shaft (p < 0.0001). Gonadectomized female animals showed an increase in osteoclast number on the periosteal surface compared with intact controls (p < 0.01). CONCLUSIONS: We documented intramembranous periosteal bone turnover in the femoral neck by histomorphometric analyses. The tissue level bone formation rate was sufficient to add substantively to femoral neck size over time. Periosteal osteoclastic activity was not the result of the emergence of intracortical tunneling at the bone surface. Sex steroid deficiency produced an increase in osteoclast numbers at the periosteal surface. This is the first systematic documentation of periosteal turnover at the femoral neck. 相似文献