全文获取类型
收费全文 | 8572篇 |
免费 | 544篇 |
国内免费 | 27篇 |
专业分类
耳鼻咽喉 | 144篇 |
儿科学 | 227篇 |
妇产科学 | 341篇 |
基础医学 | 1344篇 |
口腔科学 | 144篇 |
临床医学 | 763篇 |
内科学 | 1604篇 |
皮肤病学 | 89篇 |
神经病学 | 794篇 |
特种医学 | 355篇 |
外科学 | 893篇 |
综合类 | 58篇 |
一般理论 | 3篇 |
预防医学 | 809篇 |
眼科学 | 87篇 |
药学 | 789篇 |
中国医学 | 14篇 |
肿瘤学 | 685篇 |
出版年
2021年 | 90篇 |
2020年 | 56篇 |
2019年 | 101篇 |
2018年 | 125篇 |
2017年 | 67篇 |
2016年 | 95篇 |
2015年 | 127篇 |
2014年 | 189篇 |
2013年 | 279篇 |
2012年 | 385篇 |
2011年 | 449篇 |
2010年 | 226篇 |
2009年 | 206篇 |
2008年 | 414篇 |
2007年 | 419篇 |
2006年 | 435篇 |
2005年 | 451篇 |
2004年 | 441篇 |
2003年 | 419篇 |
2002年 | 356篇 |
2001年 | 208篇 |
2000年 | 164篇 |
1999年 | 179篇 |
1998年 | 109篇 |
1997年 | 108篇 |
1996年 | 117篇 |
1995年 | 106篇 |
1994年 | 102篇 |
1993年 | 106篇 |
1992年 | 157篇 |
1991年 | 183篇 |
1990年 | 146篇 |
1989年 | 120篇 |
1988年 | 127篇 |
1987年 | 103篇 |
1986年 | 102篇 |
1985年 | 106篇 |
1984年 | 115篇 |
1983年 | 101篇 |
1982年 | 78篇 |
1981年 | 77篇 |
1980年 | 81篇 |
1979年 | 91篇 |
1978年 | 64篇 |
1977年 | 56篇 |
1976年 | 71篇 |
1975年 | 60篇 |
1974年 | 82篇 |
1973年 | 78篇 |
1972年 | 55篇 |
排序方式: 共有9143条查询结果,搜索用时 15 毫秒
51.
Walter Matthys MD Han De Vries MS Ankie Hectors MS Maarten Veerbeek MS Willeke Heidemann MS Muriel Goud MS Jan A. R. van Hooff PhD Herman Van Engeland MD 《Child psychiatry and human development》1995,26(1):29-41
The behavior of conduct disordered (CD) children was compared with normal control (NC) children in interaction with normal
peers. Dyads consisting of a) a CD child and a normal peer and b) an NC child and the same normal peer as in a) were observed.
CD boys were less able than NC boys to neutralize incipient conflicts. Hitherto most behavioral studies of CD boys have concentrated
on their tendency to escalate conflicts but have paid very little attention to their difficulty in neutralizing conflicts. 相似文献
52.
53.
54.
Determining mechanisms that can increase ethanol consumption during a single drinking bout is central to understanding alcohol abuse. When rodents are used as models to study excessive drinking, most often limited and transient increases in bout size are found with various manipulations. In a variety of studies, investigators have reported that schedule-induced drinking can result in excessive consumption of either water or alcohol (ethanol) during a single drinking period in food-restricted rats. The question examined in this experiment was, Could a schedule-induction paradigm increase bout size in nondeprived rats already self-administering ethanol? After the rats were trained to self-administer a 10% (volume/volume) ethanol solution in a fixed daily drinking session, non-response-contingent presentation of a 10% (weight/volume) sucrose solution, on a fixed-time, 120-s schedule, was used to determine whether additional ethanol consumption could be induced. This was followed by the use of a fixed-time, 300-s schedule and then, by using the fixed-time, 120-s schedule, with the presentation of a 2% (weight/volume) sucrose solution. None of these conditions induced an increase in ethanol self-administration. The results indicate that factors that control ethanol bout size in the nondeprived rat are such that the standard schedule-induction condition seems to be ineffective if an ethanol bout has occurred in the recent past. 相似文献
55.
56.
GABAA receptor-mediated stimulation of non-adrenergic non-cholinergic neurones in the dog ileocolonic junction. 总被引:4,自引:4,他引:0
下载免费PDF全文
![点击此处可从《British journal of pharmacology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
G. E. Boeckxstaens P. A. Pelckmans M. Rampart I. F. Ruytjens T. J. Verbeuren A. G. Herman Y. M. Van Maercke 《British journal of pharmacology》1990,101(2):460-464
1. The inhibitory effects of gamma-aminobutyric acid (GABA), the GABAA receptor agonist homotaurine and the GABAB receptor agonist (+/-)-baclofen were investigated on circular muscle strips of the dog terminal ileum and ileocolonic junction. 2. In the presence of atropine, GABA and homotaurine induced concentration-dependent relaxations, similar to the non-adrenergic non-cholinergic (NANC)-mediated relaxations evoked by electrical stimulation or by acetylcholine. The ileocolonic junction was more sensitive to GABA and homotaurine than the ileum. (+/-)-Baclofen had no effect. Cross desensitization only occurred between GABA and homotaurine. 3. The GABAA receptor antagonist bicuculline shifted the concentration-response curves to GABA and homotaurine to the right. The maximal relaxation to GABA remained unaffected. 4. GABA-induced relaxations were not inhibited by timolol, guanethidine, domperidone, hexamethonium and desensitization to ATP, but were abolished by tetrodotoxin. 5. Bicuculline, and pretreatment with GABA or (+/-)-baclofen had no effect on the NANC-evoked relaxations to electrical stimulation and acetylcholine. 6. In conclusion, GABA stimulates GABAA receptors located on inhibitory NANC neurones in the dog ileocolonic junction. Our results suggest that it is unlikely that GABA is the final inhibitory NANC neurotransmitter. 相似文献
57.
Altered swelling behavior of femoral cartilage following joint immobilization in a canine model. 总被引:3,自引:0,他引:3
Daria A Narmoneva Herman S Cheung Jean Y Wang David S Howell Lori A Setton 《Journal of orthopaedic research》2002,20(1):83-91
Periods of reduced joint loading have been shown to induce changes in the biochemical composition. metabolism and mechanics of articular cartilage. In this study, changes in cartilage swelling behavior were studied following a 4-week period of joint immobilization, using a recently developed osmotic loading technique [J. Biomech, 32 (1999) 401-408]. The magnitude and distribution of swelling strains were measured in cartilage-bone samples equilibrated in physiological and hypotonic saline, relative to a hypertonic reference NaCl solution. Physicochemical parameters (glycosaminoglycan fixed charge density and water volume fraction) were determined in site-matched cartilage samples. The experimental data for swelling strains, fixed charge density and water volume fraction were used with a triphasic mechano-chemical theory [J. Biomech. Eng. 113 (1991) 245-258] to determine the effect of joint immobilization on the tensile modulus of the cartilage solid matrix. Four weeks of immobilization resulted in a significant increase in the magnitude of swelling-induced strains, and a significant decrease in fixed charge density in cartilage, as compared with the contralateral controls. Joint immobilization also resulted in decreases in values for the modulus of cartilage, as compared with the contralateral controls. Our results suggest that 4 weeks of joint immobilization had a significant effect on cartilage mechanical function that may be linked to collagen changes in the cartilage extracellular matrix. 相似文献
58.
59.
Marelise E M W Eekhoff Marjolein van der Klift Herman M Kroon Cyrus Cooper Albert Hofman Huibert A P Pols Socrates E Papapoulos 《Journal of bone and mineral research》2004,19(4):566-570
Serum ALP may be a good indicator of Paget's disease in epidemiologic studies. Subjects with raised and normal ALP from a population cohort were matched (1 in 6, total 548), and radiographs were taken. ALP was an excellent marker of the disease (RR, 10.9), but the majority of those affected had normal ALP. INTRODUCTION: Evidence from radiographic surveys of limited skeletal sites has shown that Paget's disease of bone (PDB) is common in the elderly and has a distinct geographic variation. There is no information, however, about the relation of serum alkaline phosphatase (ALP) activity, a marker of the disease, and its prevalence in the population. MATERIALS AND METHODS: We analyzed data from a well-defined Dutch population cohort (the Rotterdam study) with the following specific aims: (1) to assess the relationship between serum ALP activity and prevalence of radiographically diagnosed PDB, (2) to estimate the overall prevalence of the disease in the Netherlands, and (3) to assess the appearance of the disease with time. Using a nested case-control design, subjects with an increased serum ALP and normal serum liver enzymes were matched for gender and age (1 to 6) with subjects with normal serum ALP activity. Radiographs of the thoracic and lumbar spine, pelvis, proximal femurs, knees, wrists, and hands were taken. RESULTS AND CONCLUSIONS: PDB was diagnosed in 20.5% of subjects with elevated serum ALP activity and in 2.3% in those with normal serum ALP activity, increasing with age in both groups. The relative risk (RR) for PDB in the presence of raised serum ALP activity was 10.9 (95% CI, 4.8, 24.9). The estimated prevalence of PDB in the population was 3.6%, and the large majority (about 86%) had normal serum ALP activity, contrasting findings in bone clinics where the opposite is the case. Finally, in subjects with normal and raised serum ALP activity but no PDB at baseline, radiographs taken 6-9 years later showed no evidence of the disease. This study demonstrated that serum ALP activity is a sensitive marker of PDB in men and women >55 years of age, but the majority of those affected have normal serum ALP activity. 相似文献
60.
Michael P. Savage M.D. Santiago J. Munoz M.D. Walter M. Herman M.D. Victoria M. Kusiak M.D. 《The American journal of gastroenterology》1987,82(10):1088-1090
Chylous ascites is an uncommon clinical entity associated with lymphatic obstruction usually caused by underlying malignancy. The authors describe a patient with chylous ascites caused by constrictive pericarditis in the absence of mechanical lymphatic obstruction. Pathophysiological mechanisms for the development of chylous ascites in constrictive pericarditis include augmented lymph production and high impedance to lymph drainage caused by central venous hypertension. After pericardiectomy, the patient's ascites and edema resolved. Constrictive pericarditis should be considered a rare but potentially curable cause of chylous ascites. 相似文献