全文获取类型
收费全文 | 40451篇 |
免费 | 2754篇 |
国内免费 | 145篇 |
专业分类
耳鼻咽喉 | 269篇 |
儿科学 | 1383篇 |
妇产科学 | 946篇 |
基础医学 | 4715篇 |
口腔科学 | 745篇 |
临床医学 | 4235篇 |
内科学 | 8489篇 |
皮肤病学 | 708篇 |
神经病学 | 4018篇 |
特种医学 | 1297篇 |
外科学 | 6162篇 |
综合类 | 650篇 |
一般理论 | 62篇 |
预防医学 | 3307篇 |
眼科学 | 1049篇 |
药学 | 2827篇 |
中国医学 | 41篇 |
肿瘤学 | 2447篇 |
出版年
2023年 | 142篇 |
2022年 | 263篇 |
2021年 | 612篇 |
2020年 | 384篇 |
2019年 | 643篇 |
2018年 | 776篇 |
2017年 | 605篇 |
2016年 | 621篇 |
2015年 | 804篇 |
2014年 | 1148篇 |
2013年 | 1732篇 |
2012年 | 2658篇 |
2011年 | 2852篇 |
2010年 | 1616篇 |
2009年 | 1473篇 |
2008年 | 2608篇 |
2007年 | 2837篇 |
2006年 | 2793篇 |
2005年 | 2861篇 |
2004年 | 2715篇 |
2003年 | 2498篇 |
2002年 | 2503篇 |
2001年 | 393篇 |
2000年 | 242篇 |
1999年 | 397篇 |
1998年 | 618篇 |
1997年 | 456篇 |
1996年 | 407篇 |
1995年 | 356篇 |
1994年 | 309篇 |
1993年 | 311篇 |
1992年 | 258篇 |
1991年 | 227篇 |
1990年 | 208篇 |
1989年 | 208篇 |
1988年 | 185篇 |
1987年 | 157篇 |
1986年 | 197篇 |
1985年 | 197篇 |
1984年 | 284篇 |
1983年 | 239篇 |
1982年 | 309篇 |
1981年 | 278篇 |
1980年 | 275篇 |
1979年 | 151篇 |
1978年 | 153篇 |
1977年 | 155篇 |
1976年 | 126篇 |
1975年 | 108篇 |
1974年 | 123篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
We evaluated the effectiveness of statewide bicycle legislation using direct observation of the number of elementary and middle school children riding bicycles with and without helmets to or from school over a 7-year period. The percentage of children wearing helmets increased dramatically over the past 7 years (to a high of 81%) due to the passage of state law that required helmet usage. Rates for elementary school children were consistently higher than rates of middle school children. Numerous children still do not wear helmets, particularly older children. Further interventions are needed to promote helmet wearing. 相似文献
42.
Alan B. Storrow MD Lawrence B. Stack MD Phred Petersen 《Academic emergency medicine》1994,1(5):454-462
In the emergency department, photography requires an expedient, portable, adaptable, and relatively simple camera system to take advantage of fleeting opportunities for recording visually educational material. These prerequisites are different from those for traditional medical photography, for which relatively plentiful time and advanced equipment are routinely available. Medical photography departments provide an invaluable service, but are rarely convenient for immediate or spontaneous emergency. department photographs. Although no single system or technique is optimal in all these areas, the authors find certain components and approaches work well. They review photographic equipment, paying attention to speed, ease of use, and quality of output. They also review simple techniques such as film choice, lighting, close-up photography, standardization, copy work, and radiographs. Attention to these details can help the inexperienced photographer obtain a system and begin to enjoy the rewards of effective photography in the emergency department. 相似文献
43.
David M. Kelley Alan Lichtenstein Jianyi Wang Anna N. Taylor Steven M. Dubinett 《Immunopharmacology and immunotoxicology》1994,16(2):139-148
Previous studies have suggested that corticotropin-releasing factor (CRF) has immunoregulatory effects in addition to its neuroendocrine role. We examined the ability of CRF to inhibit lipopolysaccharide (LPS)-induced pulmonary vascular leak in vivo. Female BALB/C mice were treated with either normal saline (NS) or CRF prior to injection with LPS. Pulmonary vascular leak was inhibited by CRF as assessed by measurement of lung wet-to-dry ratios. The stress-induced increase in serum corticosterone levels in mice injected with LPS alone was not further increased by treatment with CRF. This indicates that the effect of CRF was not mediated centrally by stimulation of endogenous steroid release. Histologic examination of the lungs revealed that leukocyte infiltration was significantly depressed in CRF-treated mice thus confirming the protective effect of CRF. In addition, a modest prolongation of survival was demonstrated in CRF-treated mice following challenge with LPS (p=.08). These data indicate the potential utility of CRF as a modulator of pulmonary vascular leak. 相似文献
44.
Alan L Whone Sarah Von Spiczak Mark Edwards Enza-Maria Valente Alexander Hammers Kailash P Bhatia David J Brooks 《Movement disorders》2004,19(12):1498-1503
The opioid transmitters enkephalin and dynorphin are known to regulate pallidal output and consequently cortical excitability. Indeed, abnormal basal ganglia opioid transmission has been reported in several involuntary movement disorders, including levodopa-induced dyskinesias in Parkinson's disease (PD), tardive dyskinesias/dystonia, Huntington's disease, and Tourette's syndrome. Moreover, a previous 11C-diprenorphine PET study investigating levodopa-induced dyskinesias found reduced opioid receptor availability in PD with but not without dyskinesias. We wished to investigate if a similar alteration in basal ganglia opioid binding was present in DYT1 primary torsion dystonia (PTD). Regional cerebral 11C-diprenorphine binding was investigated in 7 manifesting carriers of the DYT1 gene and 15 age-matched normal controls using a region-of-interest (ROI) approach and statistical parametric mapping (SPM). No difference in regional mean 11C-diprenorphine binding was found between DYT1-PTD and controls, and no correlation between the severity of dystonia and opioid binding was seen. We conclude that aberrant opioid transmission is unlikely to be present in DYT1-PTD and altered opioid transmission is not a common mechanism underlying all disorders of involuntary movement. 相似文献
45.
46.
Alan J. Lewis Janet Parker Joanne Diluigi Louis J. Datko Richard P. Carlson 《Immunopharmacology and immunotoxicology》1981,3(3):289-308
Delayed hypersensitivity (DH) was induced in the footpads of mice sensitized to methylated bovine serum albumin (MBSA). The magnitude of this DH response increased with increasing sensitizing concentration of MBSA. Levamisole administered 1 hr prior to MBSA challenge stimulated the DH response and this was optimal using subliminal sensitizing concentrations of antigen. A number of antirheumatic agents, immunomodulators mediator antagonists and antiallergies were subsequently examined using the subliminal sensitizing concentration of MBSA. The same drugs were also evaluated using a normal sensitizing procedure. These studies indicate that the sensitizing concentration of antigen is critical in establishing whether a drug will stimulate or suppress a DH response. 相似文献
47.
Reinherz Helen Gordon Alan L. Morris Kathleen M. Anastas Jeane W. 《The journal of primary prevention》1983,4(2):73-95
Journal of Prevention - The major issues involved in the design and implementation of effective school screening programs are addressed, using data from a longitudinal study following over 500... 相似文献
48.
49.
David Rempel Peter J. Keir W. Paul Smutz Alan Hargens 《Journal of orthopaedic research》1997,15(3):422-426
The purpose of this study was to explore the relationship between carpal tunnel pressure and fingertip force during a simple pressing task. Carpal tunnel pressure was measured in 15 healthy volunteers by means of a saline-filled catheter inserted percutaneously into the carpal tunnel of the nondominant hand. The subjects pressed on a load cell with the tip of the index finger and with 0, 6, 9, and 12 N of force. The task was repeated in 10 wrist postures: neutral; 10 and 20° of ulnar deviation; 10° of radial deviation; and 15, 30, and 45° of both flexion and extension. Fingertip loading significantly increased carpal tunnel pressure for all wrist angles (p = 0.0001). Post hoc analyses identified significant increases (p <0.05) in carpal tunnel pressure between unloaded (0 N) and all loaded conditions, as well as between the 6 and 12 N load conditions. This study demonstrates that the process whereby fingertip loading elevates carpal tunnel pressure is independent of wrist posture and that relatively small fingertip loads have a large effect on carpal tunnel pressure. It also reveals the response characteristics of carpal tunnel pressure to fingertip loading, which is one step in understanding the relationship between sustained grip and pinch activities and the aggravation or development of median neuropathy at the wrist. 相似文献
50.
Michael P Hill Erwan Bezard Steven G McGuire Alan R Crossman Jonathan M Brotchie Ann Michel Renee Grimée Henrik Klitgaard 《Movement disorders》2003,18(11):1301-1305
Long-term dopamine replacement therapy of Parkinson's disease leads to the occurrence of dyskinesias. Altered firing patterns of neurons of the internal globus pallidus, involving a pathological synchronization/desynchronization process, may contribute significantly to the genesis of dyskinesia. Levetiracetam, an antiepileptic drug that counteracts neuronal (hyper)synchronization in animal models of epilepsy, was assessed in the MPTP-lesioned marmoset model of Parkinson's disease, after coadministration with (1) levodopa (L-dopa) or (2) ropinirole/L-dopa combination. Oral administration of levetiracetam (13-60 mg/kg) in combination with either L-dopa (12 mg/kg) alone or L-dopa (8 mg/kg)/ropinirole (1.25 mg/kg) treatments was associated with significantly less dyskinesia, in comparison to L-dopa monotherapy during the first hour after administration. Thus, new nondopaminergic treatment strategies targeting normalization of abnormal firing patterns in basal ganglia structures may prove useful as an adjunct to reduce dyskinesia induced by dopamine replacement therapy without affecting its antiparkinsonian action. 相似文献