全文获取类型
收费全文 | 76454篇 |
免费 | 9734篇 |
国内免费 | 218篇 |
专业分类
耳鼻咽喉 | 581篇 |
儿科学 | 1993篇 |
妇产科学 | 2717篇 |
基础医学 | 7799篇 |
口腔科学 | 1094篇 |
临床医学 | 21548篇 |
内科学 | 13195篇 |
皮肤病学 | 874篇 |
神经病学 | 5612篇 |
特种医学 | 2411篇 |
外科学 | 10520篇 |
综合类 | 835篇 |
一般理论 | 57篇 |
预防医学 | 7453篇 |
眼科学 | 1337篇 |
药学 | 4230篇 |
1篇 | |
中国医学 | 54篇 |
肿瘤学 | 4095篇 |
出版年
2023年 | 1092篇 |
2022年 | 555篇 |
2021年 | 1415篇 |
2020年 | 1283篇 |
2019年 | 1336篇 |
2018年 | 2419篇 |
2017年 | 2309篇 |
2016年 | 2447篇 |
2015年 | 2730篇 |
2014年 | 3349篇 |
2013年 | 4290篇 |
2012年 | 4333篇 |
2011年 | 4723篇 |
2010年 | 3218篇 |
2009年 | 3243篇 |
2008年 | 4140篇 |
2007年 | 4309篇 |
2006年 | 4219篇 |
2005年 | 4006篇 |
2004年 | 3683篇 |
2003年 | 3488篇 |
2002年 | 3267篇 |
2001年 | 1352篇 |
2000年 | 1117篇 |
1999年 | 1254篇 |
1998年 | 1231篇 |
1997年 | 1218篇 |
1996年 | 1127篇 |
1995年 | 1079篇 |
1994年 | 842篇 |
1993年 | 734篇 |
1992年 | 793篇 |
1991年 | 725篇 |
1990年 | 738篇 |
1989年 | 648篇 |
1988年 | 569篇 |
1987年 | 507篇 |
1986年 | 506篇 |
1985年 | 568篇 |
1984年 | 472篇 |
1983年 | 399篇 |
1982年 | 335篇 |
1981年 | 320篇 |
1980年 | 262篇 |
1979年 | 318篇 |
1978年 | 291篇 |
1977年 | 249篇 |
1976年 | 248篇 |
1974年 | 241篇 |
1972年 | 269篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
Further evidence of dopamine transporter dysregulation in ADHD: a controlled PET imaging study using altropane. 总被引:4,自引:0,他引:4
Thomas J Spencer Joseph Biederman Bertha K Madras Darin D Dougherty Ali A Bonab Elijahu Livni Peter C Meltzer Jessica Martin Scott Rauch Alan J Fischman 《Neuropsychopharmacology》2007,62(9):1059-1061
BACKGROUND: The dopamine transporter (DAT) is known to be a key regulator of dopamine, and recent studies of genetics, treatment, and imaging have highlighted the role of DAT in attention-deficit/hyperactivity disorder (ADHD). The findings of in vivo neuroimaging of DAT in ADHD have been somewhat discrepant, however. METHOD: Dopamine transporter binding was measured using a highly selective ligand (C-11 altropane) and positron emission tomography (PET). The sample consisted of 47 well-characterized, treatment-na?ve, nonsmoking, non-comorbid adults with and without ADHD. Additionally, control subjects had few symptoms of ADHD. RESULTS: Results showed significantly increased DAT binding in the right caudate in adults with ADHD compared with matched control subjects without this disorder. CONCLUSIONS: These results confirm abnormal DAT binding in the striatum of adults with ADHD and provide further support that dysregulation of DAT may be an important component of the pathophysiology of ADHD. 相似文献
62.
63.
Javairiah Fatima Scott G. Houghton Michael G. Sarr 《Journal of gastrointestinal surgery》2007,11(8):1052-1056
Small bowel transplantation (SBT) is associated with poorly understood enteric dysfunction. The study of SBT in mice is hindered
by the technical difficulty of orthotopic SBT in the mouse. Our aim was to develop an easy preparation of extrinsic denervation
of the entire jejunoileum in mice as a model of orthotopic SBT. All neurolymphatic tissues accompanying the superior mesenteric
artery (SMA) and vein (SMV) were ligated just distal to the middle colic vessels. The SMA and SMV were then stripped of investing
adventitia, and the mesentery to jejunum and colon were transected radially. Jejunum and colon were not transected and reanastomosed.
To confirm extrinsic denervation 1, 3, and 6 months later, segments of small bowel were stained for protein gene product 9.5
(PGP9.5) and tyrosine hydroxylase (TH). Tyrosine hydroxylase immunoreactive intensity was then quantified using a semiquantitative
analysis. Immunohistochemical fluorescence showed persistence of PGP9.5 immunoreactivity confirming enteric nerves in jejunoileum;
however, there was no TH immunoreactivity in jejunoileum in denervated mice despite the expected preservation of TH immunoreactivity
in the still-innervated duodenum at 1 month. At 3 months, sparse immunoreactivity for TH was present, and by 6 months, reinnervation
of TH-containing nerves appeared similar to controls. Quantification of intensity at each time-point further confirmed this
trend. This technique in the mouse accomplishes a complete extrinsic denervation of jejunoileum early postoperatively (1 and
3 months); reinnervation occurs by 6 months. This is an easily learned murine model of orthotopic SBT.
Presented at the American Gastroenterological Association during Digestive Disease Week in Los Angeles, CA, as a poster presentation
on May 23 2006. Abstract published in GastroenterologyE 2006; 130:A604. 相似文献
64.
65.
D. Grant Richards Kevin G. Whithear Peter C. Scott Robin B. Gasser 《Acta parasitologica / Witold Stefański Institute of Parasitology, Warszawa, Poland》2006,51(2):156-159
Coccidiosis of chickens, caused by species of Eimeria (Protozoa, Apicomplexa), is an intestinal disease of major economic importance worldwide. In the present study, the reproductive
characteristics of a precocious line (designated E. tenella Rt3+15) from Australia were investigated in chicken embryos and the implications of the findings briefly discussed. 相似文献
66.
Amit Badhwar Thomas L Forbes Marge B Lovell Alison A Dungey Sarah D McCarter Jeffrey R Scott Guy DeRose Kenneth A Harris Richard F Potter 《Canadian journal of surgery》2004,47(5):352-358
BACKGROUND: Ischemic preconditioning (IPC) has been found in animals to have a protective effect against future ischemic injury to muscle tissue. Such injury is unavoidable during some surgical procedures. To determine whether chronic ischemia in the lower extremities would imitate IPC and reduce ischemic injury during vascular surgery, we designed a controlled clinical study. PATIENTS AND METHODS: Two groups of patients at a university-affiliated medical centre with chronic lower-extremity ischemia served as models of IPC: 6 patients awaiting femoral distal bypass (FDB) and 4 scheduled for aortobifemoral (ABF) bypass grafting for aortoiliac occlusive disease. Seven patients undergoing elective open repair of an infrarenal abdominal aortic aneurysm (AAA) were chosen as non-IPC controls. Three hematologic indicators of skeletal-muscle injury, lactate dehydrogenase (LDH), creatine kinase (CK) and myoglobin, were measured before placement of the proximal clamp, during surgical ischemia, immediately upon reperfusion, 15 minutes after and 1 hour after reperfusion, and during the first, second and third postoperative days. RESULTS: Baseline markers of skeletal-muscle injury were similar in all groups. In postreperfusion samples, concentrations of muscle-injury markers were significantly lower in the 2 PC groups than in the control group. For example, at day 2, LDH levels were increased by about 30% over baseline measures in the elective AAA (control) group, whereas levels in the FDB and ABF groups remained statistically unchanged from baseline. Myoglobin in controls had increased by 977%, but only by 160% in the FDB and 528% in the ABF groups. CK levels, in a similar trend, were 1432% higher in the control group and only 111% (FDB) and 1029% (ABF) in the study groups. Taken together, these data represent a significant level of protection. CONCLUSIONS: Patients with chronic lower-extremity ischemia suffered less severe ischemic injury after a period of acute ischemia than those with acute ischemia alone. Ischemic preconditioning is one proposed mechanism to help explain this protective effect. 相似文献
67.
68.
M. Scott DeBerard Rick A. LaCaille Glen Spielmans Alan Colledge Mary Ann Parlin 《The spine journal》2009,9(3):193-203
Background contextLumbar discectomy is the most common type of back surgery performed in the United States. Outcomes after this procedure can be variable and it appears that Workers' Compensation patients might be at increased risk for poor outcomes.PurposeTo examine long-term multidimensional outcomes of lumbar discectomy within a cohort of Workers' Compensation patients from Utah and identify presurgical biopsychosocial factors related to poor outcomes.Study design/settingA retrospective cohort study consisting of a review of presurgical medical records and assessment of patient outcomes via a telephone survey. Outcomes were assessed at least 2 years postsurgery.Patient sampleA consecutive sample of 271 workers from Utah who underwent lumbar discectomy from 1994 to 1999. A total of 134 patients were surveyed at the time of follow-up.Outcome measuresPatient satisfaction, Roland-Morris Disability Questionnaire, SF-36v2, and Stauffer-Coventry Index.MethodsA retrospective review of presurgical biopsychosocial variables and outcome assessment via telephone survey was conducted.ResultsWork disability rate for the cohort was 12.7% (17/134). Analysis of patient satisfaction, back pain-related dysfunction, and the Short-Form Health Survey-36 subscales indicated approximately 25% of patients experienced poor outcomes. Older age, number of comorbid health conditions, assigned case manager, litigation, and time delay from injury to surgery were consistently statistically significant predictors (p<.05) of poor outcomes.ConclusionsResults of this study suggest that compensated back surgery patients are at greater risk for poor lumbar discectomy outcomes than noncompensation patients. Presurgery correlates of poor outcomes may be useful in identifying high-risk compensation patients. 相似文献
69.
Qualitative Data Analysis: An Introduction 总被引:1,自引:1,他引:0
70.