全文获取类型
收费全文 | 19962篇 |
免费 | 1450篇 |
国内免费 | 53篇 |
专业分类
耳鼻咽喉 | 158篇 |
儿科学 | 706篇 |
妇产科学 | 573篇 |
基础医学 | 2622篇 |
口腔科学 | 356篇 |
临床医学 | 3081篇 |
内科学 | 3451篇 |
皮肤病学 | 228篇 |
神经病学 | 1395篇 |
特种医学 | 709篇 |
外国民族医学 | 2篇 |
外科学 | 2453篇 |
综合类 | 290篇 |
一般理论 | 48篇 |
预防医学 | 2424篇 |
眼科学 | 498篇 |
药学 | 1192篇 |
中国医学 | 21篇 |
肿瘤学 | 1258篇 |
出版年
2023年 | 92篇 |
2022年 | 146篇 |
2021年 | 324篇 |
2020年 | 210篇 |
2019年 | 360篇 |
2018年 | 424篇 |
2017年 | 308篇 |
2016年 | 345篇 |
2015年 | 383篇 |
2014年 | 549篇 |
2013年 | 893篇 |
2012年 | 1197篇 |
2011年 | 1368篇 |
2010年 | 729篇 |
2009年 | 704篇 |
2008年 | 1261篇 |
2007年 | 1222篇 |
2006年 | 1161篇 |
2005年 | 1244篇 |
2004年 | 1212篇 |
2003年 | 1091篇 |
2002年 | 1053篇 |
2001年 | 321篇 |
2000年 | 326篇 |
1999年 | 296篇 |
1998年 | 238篇 |
1997年 | 207篇 |
1996年 | 171篇 |
1995年 | 154篇 |
1994年 | 145篇 |
1993年 | 138篇 |
1992年 | 216篇 |
1991年 | 174篇 |
1990年 | 191篇 |
1989年 | 194篇 |
1988年 | 169篇 |
1987年 | 162篇 |
1986年 | 146篇 |
1985年 | 161篇 |
1984年 | 146篇 |
1983年 | 141篇 |
1982年 | 114篇 |
1981年 | 112篇 |
1980年 | 94篇 |
1979年 | 111篇 |
1978年 | 111篇 |
1976年 | 81篇 |
1975年 | 79篇 |
1974年 | 82篇 |
1973年 | 72篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Michael P. Recht Josef Kramer Cheryl A. Petersilge Joseph Yu Mini Pathria Debra Trudell David J. Sartoris Donald Resnick 《Journal of magnetic resonance imaging : JMRI》1994,4(2):173-177
Although magnetic resonance (MR) images of the glenohumeral joint frequently demonstrate intraarticular fluid, no specific criteria have, to the authors' knowledge, been published that allow accurate assessment of the amount of fluid present. Also, despite the increasing use of MR arthrography of the shoulder, the optimal amount of intra-articular fluid that should be used with this technique has not been determined. The authors progressively distended the glenohumeral joint in six cadaveric shoulder specimens with a dilute gadopentetate dimeglumine solution and obtained MR images after injection of 2, 5, 10, 15, and 20 mL of the solution. The pattern of fluid distribution was evaluated, and these results were then used to estimate the amount of fluid that was present in the glenohumeral joint on MR images of 20 shoulders obtained in 12 asymptomatic volunteers. In 14 of these shoulders, intraarticular fluid was present; however, in none was more than 2 mL evident. Results of the cadaveric study also indicated that 15 mL of intraarticular fluid appears to be the optimal amount for MR arthrography. 相似文献
42.
43.
Laura K Brennan Elizabeth A Baker Debra Haire-Joshu Ross C Brownson 《Health education & behavior》2003,30(6):740-755
Although the relationship of psychosocial factors to physical activity has been explored, there is increased interest in how perceptions of the community environment influence behavior. However, few methodological studies have incorporated perceptions of the social and community environment (protective social factors) or addressed key measurement issues. Computer-assisted telephone interviews were administered to a national sample of 1,818 U.S. adults. Unadjusted and multivariate-adjusted odds ratios were calculated to compare active and inactive participants by Protective Social Factors (PSF) scores and selected sociodemographics. Confirmatory factor analysis and reliability analysis suggested strong PSF scale psychometric properties (alpha = .92). After adjustment for potential confounders, a 10-point rise in the PSF score resulted in a 12% increased likelihood of meeting Centers for Disease Control and Prevention/American College of Sports Medicine recommendations. Additional analyses indicated that greater perceived PSFs were associated with meeting these recommendations among Whites but not among African Americans. 相似文献
44.
The use of ibuprofen by patients with systemic lupus erythematosus poses a major threat of aseptic meningitis. Although previously reported cases have all been in young adults, our case of ibuprofen-induced meningitis occurred in a 73-year-old woman. This report greatly expands the age population that may suffer meningitis from this analgesic, now available over the counter, and emphasizes the importance of recognizing this causative relationship in patients with headache. 相似文献
45.
The effects of the calcium antagonists verapamil and nifedipine on blood glucose levels, glucose tolerance, insulin secretion during glucose tolerance and hypoglycaemic effect of tolbutamide were studied in normal nondiabetic rabbits. Daily dosage of 40 mg/kg verapamil and 5 mg/kg nifedipine given orally up to 7 days did not affect blood glucose level, glucose tolerance, insulin secretion during glucose tolerance and hypoglycaemic activity of tolbutamide 250 mg/kg p.o. 相似文献
46.
J G Gilbert 《The New Zealand medical journal》1987,100(819):141-142
Auricular chondritis occurred in a patient following a course of auricular acupuncture administered to help the patient give up smoking. Despite immediate treatment the condition pursued a long course resulting in considerable morbidity and some deformity of the ear. Twenty months after presentation the ear is not completely stable. Acupuncture should be considered a form of penetrating trauma which may induce perichondritis or chondritis in the auricle. 相似文献
47.
Horizontal connections are a principal component of intrinsic cortical circuitry. They arise mainly from pyramidal cells and course parallel to the brain's surface for distances as long as 8 mm, linking columns with shared orientation preference and allowing cells to integrate visual information from outside their receptive fields. We examined the synaptic physiology of the horizontal pathway in slices of the cat's striate cortex and found that activating lateral fibers produced both excitation and inhibition. We recorded the postsynaptic responses of identified pyramidal cells in layer 2 + 3 of area 17 to electrical shocks applied at three sites: in the home column of the impaled neuron either in layer 2 + 3 or 4, or at a lateral distance of 0.9-3 mm in layer 2 + 3. Within the home column, suprathreshold stimuli produced compound EPSPs with action potentials, followed by fast, GABAAergic IPSPs and a slower, GABABergic IPSP. For the distant stimulating site, the threshold response was an EPSP. Stronger shocks frequently evoked a disynaptic, GABAAergic IPSP that truncated the EPSP and could dominate the postsynaptic response. At the resting potential, the horizontally evoked EPSP was too small to elicit spikes. With depolarization of the membrane, however, it grew several hundred-fold. This amplification was blocked by N-(2,6-dimethylphenylcarbamoylmethyl)triethylammonium bromide (QX-314), but not by 2-amino-5-phosphonovalerate (APV), indicating that it was mediated by Na+ channels, rather than by NMDA receptors. We propose that the horizontal connections provide the means for stimuli outside the receptive field to modulate activity elicited within its confines. The voltage-dependent enhancement of the laterally evoked EPSP may explain why stimulating the surround by itself fails to drive cells but can facilitate their response to stimuli within the receptive field. The ability to initiate disynaptic inhibition from lateral sites shows that recruiting appropriate groups of horizontal fibers can also have a suppressive effect. Thus, the effect of horizontal input is state dependent, with the size and sign of the laterally evoked response changing according to the balance of converging inputs. 相似文献
48.
Kathleen M Grant Stephanie Sinclair Kelley Lynette M Smith Sangeeta Agrawal James R Meyer Debra J Romberger 《Alcohol》2007,41(5):381-391
This is a double-blind placebo-controlled study of sustained-release bupropion as a smoking cessation aid in alcoholics undergoing treatment for their alcoholism. Participants (N=58) were enrolled within 1 week of entry into alcohol treatment from community and Veterans Affairs Substance Use Disorder programs. All participants received nicotine patch and were invited to attend a smoking cessation lecture and group. Cigarette smoking and alcohol outcomes were measured at 6 months. Bupropion when added to nicotine patch did not improve smoking outcomes. One third of participants on bupropion reported discontinuing the drug during weeks 1-4. Participants reported cigarette outcomes with nicotine patch that are similar to those seen in the general population. All study participants significantly reduced cigarette use. Comorbid affective disorder or antipersonality disorder did not affect outcomes. Alcohol outcomes were improved in those who discontinued cigarettes. 相似文献
49.
Gregg H. Gilbert DDS Laurence G. Branch PhD Jeffrey Longmate PhD 《Journal of public health dentistry》1992,52(5):277-287
Veterans who were eligible for dental care in Department of Veterans Affairs (VA) facilities at no monetary cost responded to a mailed questionnaire. Seventy-one percent were aware that they were actually eligible for VA dental care. However, only 48 percent reported the VA as their only or primary source of dental care. Eligibility status, perceived quality of VA dental care, use of VA medical care, perception that one's income meets expenses, and perceived need for dental care were significant correlates of using the VA as one's current source of dental care. Level of formal education, perception that one's income meets expenses, transportation pattern, geographic distance from a VA facility, and eligibility status were significant correlates of using the VA as one's current medical care source. Research on VA utilization offers the opportunity to study issues of access to, and use of, a large public health care system whose patients largely receive care at no monetary cost. Veterans' use of VA dental and medical care is apparently influenced by a wide variety of factors, ranging from barriers to access to non-VA systems, to characteristics of the VA delivery system itself, to need for treatment. 相似文献
50.