全文获取类型
收费全文 | 36094篇 |
免费 | 2481篇 |
国内免费 | 138篇 |
专业分类
耳鼻咽喉 | 427篇 |
儿科学 | 937篇 |
妇产科学 | 603篇 |
基础医学 | 4443篇 |
口腔科学 | 673篇 |
临床医学 | 3415篇 |
内科学 | 8682篇 |
皮肤病学 | 564篇 |
神经病学 | 3228篇 |
特种医学 | 1183篇 |
外国民族医学 | 1篇 |
外科学 | 5078篇 |
综合类 | 456篇 |
一般理论 | 17篇 |
预防医学 | 2919篇 |
眼科学 | 784篇 |
药学 | 2630篇 |
1篇 | |
中国医学 | 62篇 |
肿瘤学 | 2610篇 |
出版年
2023年 | 175篇 |
2022年 | 257篇 |
2021年 | 645篇 |
2020年 | 409篇 |
2019年 | 624篇 |
2018年 | 742篇 |
2017年 | 554篇 |
2016年 | 603篇 |
2015年 | 653篇 |
2014年 | 1038篇 |
2013年 | 1523篇 |
2012年 | 2311篇 |
2011年 | 2379篇 |
2010年 | 1331篇 |
2009年 | 1206篇 |
2008年 | 2282篇 |
2007年 | 2516篇 |
2006年 | 2573篇 |
2005年 | 2494篇 |
2004年 | 2431篇 |
2003年 | 2346篇 |
2002年 | 2282篇 |
2001年 | 264篇 |
2000年 | 191篇 |
1999年 | 327篇 |
1998年 | 493篇 |
1997年 | 386篇 |
1996年 | 369篇 |
1995年 | 351篇 |
1994年 | 317篇 |
1993年 | 280篇 |
1992年 | 217篇 |
1991年 | 166篇 |
1990年 | 161篇 |
1989年 | 151篇 |
1988年 | 153篇 |
1987年 | 170篇 |
1986年 | 141篇 |
1985年 | 170篇 |
1984年 | 272篇 |
1983年 | 243篇 |
1982年 | 336篇 |
1981年 | 284篇 |
1980年 | 257篇 |
1979年 | 118篇 |
1978年 | 162篇 |
1977年 | 155篇 |
1976年 | 146篇 |
1975年 | 109篇 |
1974年 | 96篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Diarrheal diseases have a well recognized negative effect on children's growth, probably due in part to reduced dietary intake during illness. Previous studies have shown that the effects of diarrhea on dietary intake are greater among hospitalized children than among those observed in their homes. Breast milk intake does not change during diarrhea, however, so breast-fed children are less likely to reduce their total energy and nutrient intakes. Recent analyses of clinical studies found that acidosis and dehydration were most closely associated with reduced dietary intake of hospitalized patients. The implications of these and other studies for the dietary management of patients during and after diarrhea are discussed. 相似文献
52.
Kenneth L. Noller Roger Bibace PhD 《American journal of obstetrics and gynecology》2003,189(5):1511-1516
53.
Carmen Cristea Janvin Jan Petter Larsen David P Salmon Douglas Galasko Kenneth Hugdahl Dag Aarsland 《Movement disorders》2006,21(3):337-342
We describe the pattern of cognitive profiles within a community-based sample of patients with Parkinson's disease (PD) and dementia (PDD) using cluster analyses, and compare the results with data from patients with Alzheimer's disease (AD) and dementia with Lewy bodies (DLB). Fifty patients with PDD and 39 with AD from Stavanger, Norway, and 62 patients with DLB from San Diego, CA, USA were diagnosed by either standardized clinical procedures or criteria (all PDD and all AD cases) or necropsy (all DLB cases). Four subgroups were identified: two subgroups with a subcortical cognitive profile (one with mild and one with moderate dementia severity), one subgroup with global impairment and severe dementia, and one subgroup with a cortical cognitive profile and moderate dementia. Of the patients with PDD and with DLB, 56% and 55%, respectively, had a subcortical cognitive profile, compared with only 33% of the AD patients. Conversely, 30% of the patients with PDD and 26% of those with DLB had a cortical cognitive profile, compared with 67% of the patients with AD. These findings suggest that in some patients with PDD, frontosubcortical changes are the main contributing factor to dementia, whereas in other patients, cortical and hippocampal changes are more important. 相似文献
54.
55.
56.
Treatment of experimentally induced atherosclerosis in swine iliac arteries: A comparison of self-expanding and balloon-expanded stents 总被引:1,自引:0,他引:1
Chamaree Chuapetcharasopon Kenneth C. Wright Sidney Wallace Richard L. Dobben Cesare Gianturco 《Cardiovascular and interventional radiology》1992,15(3):143-150
Atherosclerosis was induced in 20 Hanford miniature swine. Subsequently, one iliac artery lesion in each of 16 pigs was stented
with either a self-expanding (8 pigs) or a balloon-expanded (8 pigs) stent. Immediately after stent placement, 4 animals in
each group were taken off the atherogenic diet and continued on normal chow for the remainder of the study. Four months after
stents were placed, atherosclerosis and the mural changes associated with the stent were more clearly evident in the arteries
of the pigs continued on the atherogenic diet. These pigs also exhibited significantly more neointimal proliferation. In addition,
the arteries containing the balloon-expanded stents showed more extensive and complex intimal changes when compared with arteries
with self-expanding stents. Although both stent designs were equally effective in maintaining vascular patency, the balloon-expanded
stent was more traumatic to the vessel wall which resulted in a significantly greater neointimal thickness. 相似文献
57.
Frame-based stereotactic body radiation therapy (SBRT), such as that conducted with Elekta's Stereotactic Body Frame, can provide an extra measure of precision in the delivery of radiation to extracranial targets, and facilitates secure patient immobilization. In this paper, we review the steps involved in optimal use of an extra-cranial immobilization device for SBRT treatments. Our approach to using frame-based SBRT consists of 4 steps: patient immobilization, tumor and organ motion control, treatment/planning correlation, and daily targeting with pretreatment quality assurance. Patient immobilization was achieved with the Vac-Loc bag, which uses styrofoam beads to conform to the patient's shape comfortably within the body frame. Organ and motion control was assessed under fluoroscopy and controlled via a frame-mounted abdominal pressure plate. The compression screw was tightened until the diaphragmatic excursion range was < 1 cm. Treatment planning was performed using the Philips Pinnacle 6.2b system. In this treatment process, a 20 to 30 noncoplanar beam arrangement was initially selected and an inverse beam weight optimization algorithm was applied. Those beams with low beam weights were removed, leaving a manageable number of beams for treatment delivery. After planning, daily targeting using computed tomography (CT) to verify x-, y-, and z-coordinates of the treatment isocenter were used as a measure of quality assurance. We found our daily setup variation typically averaged < 5 mm in all directions, which is comparable to other published studies on Stereotactic Body Frame. Treatment time ranged from 30 to 45 minutes. Results demonstrate that patients have experienced high rates of local control with acceptable rates of severe side effects - by virtue of the tightly constrained treatment fields. The body frame facilitated comfortable patient positioning and quality assurance checks of the tumor, in relation to another set of independent set of coordinates defined by the body frame fiducials. The ability to impose abdominal compression proved to be a simple way to reduce target and tissue motion. SBRT with Stereotactic Body Frame enables comfortable patient immobilization and facilitates repeated registering and re-registering of the patient to the frame. With the body frame, large-dose-per fraction treatment is possible for localized tumor deposits with the aim of attaining a more therapeutic result. 相似文献
58.
Percutaneous absorption of 2,6-di-tert-butyl-4-nitrophenol (DBNP) in isolated perfused porcine skin.
Alfred O Inman Kenneth R Still Warren W Jederberg Robert L Carpenter Jim E Riviere James D Brooks Nancy A Monteiro-Riviere 《Toxicology in vitro》2003,17(3):289-292
DBNP (2,6-di-tert-butyl-4-nitrophenol) has been reported as a potential contaminant in submarines. This yellow substance forms when lubrication oil mist containing the antioxidant additive 2,6-di-tert-butylphenol passes through an electrostatic precipitator and is nitrated. Percutaneous absorption of 14C-DBNP was assessed in the isolated perfused porcine skin flap (IPPSF). Four treatments were studied (n=4 flaps/treatment): 40.0 microgram/cm(2) in 100% ethanol; 40.0 microgram/cm(2) in 85% ethanol/15% H(2)O; 4.0 microgram/cm(2) in 100% ethanol; and 4.0 microgram/cm(2) in 85% ethanol/15% water. DBNP absorption was minimal across all treatment groups, with the highest absorption detected being only 1.08% applied dose in an aqueous ethanol group. The highest mass of 14C-DBNP absorbed was only 0.5 microgram. The majority of the applied dose remained on the surface of the skin. This suggests that there is minimal dermal exposure of DBNP when exposed topically to skin. 相似文献
59.
Siberian ginseng (Eleutheroccus senticosus) effects on CYP2D6 and CYP3A4 activity in normal volunteers. 总被引:3,自引:0,他引:3
Jennifer L Donovan C Lindsay DeVane Kenneth D Chavin Robin M Taylor John S Markowitz 《Drug metabolism and disposition》2003,31(5):519-522
Siberian ginseng ([SG]; Eleutherococcus senticosus) is a commonly used herbal preparation. The objective of this study was to assess in normal volunteers (n = 12) the influence of a standardized SG extract on the activity of cytochrome P450 CYP2D6 and 3A4. Probe substrates dextromethorphan (CYP2D6 activity) and alprazolam (CYP3A4 activity) were administered orally at baseline and again following treatment with SG (1 x 485 mg twice daily) for 14 days. Urinary concentrations of dextromethorphan and dextorphan were quantified, and dextromethorphan metabolic ratios (DMRs) were determined at baseline and after SG treatment. Likewise, plasma samples were collected (0-60 h) for alprazolam pharmacokinetics at baseline and after SG treatment to assess effects on CYP3A4 activity. Validated high performance liquid chromatography methods were used to quantify all compounds and relevant metabolites. There were no statistically significant differences between pre- and post-SG treatment DMRs indicating a lack of effect on CYP2D6 (P > 0.05). For alprazolam there also were no significant differences in the pharmacokinetic parameters determined by noncompartmental modeling (C(max), T(max), area under the curve, half-life of elimination) indicating that SG does not significantly induce or inhibit CYP3A4 (P > 0.05). Our results indicate that standardized extracts of SG at generally recommended doses for over-the-counter use are unlikely to alter the disposition of coadministered medications primarily dependent on the CYP2D6 or CYP3A4 pathways for elimination. 相似文献
60.
Kenneth W. Locke Robert W. Dunn John W. Hubbard Cheri L. Vanselous Michael Cornfeldt Stuart Fielding Joseph T. Strupczewski 《Drug development research》1990,19(3):239-256
HP 818 (1-benzoyl-6-fluoro-3-(1-methyl-4-piperidinyl)-1H-indazole) exhibits the profile of a potent nonnarcotic analgesic with neuroleptic properties. HP 818 blocks the effects of chemical (phenylquinone), pressure (tail clip), and radiant heat (tail flick) painful stimuli in mice (ED50 values of 0.3, 1.2, and 4.1 mg/kg s.c., respectively). This compound displays antinociceptive activity by the subcutaneous, oral, and intravenous routes of administration. It is also effective in the shock titration assay in squirrel monkeys and in a model of surgically induced pain. The rank order of potency of HP 818 and several other standard compounds in these tests for analgesia was Innovar > fentanyl > HP 818 > codeine > droperidol. In addition to its antinociceptive effects, HP 818 possesses neuroleptic properties. It is active in the climbing mouse, pole climb avoidance, and intracranial self-stimulation assays (ED50 values of 1.8, 1.7, and 2.5 mg/kg i.p., respectively). Moreover, HP 818 inhibits amphetamine- and apomorphine-induced stereotypy, indicative of D2-dopaminergic blocking properties. HP 818, unlike typical neuroleptic agents, does not induce supersensitivity to the effects of apomorphine when administered chronically in mice. In contrast to the clinical standard neuroleptanalgesic Innovar, HP 818 (1.0–3.0 mg/kg i.v.) produces no significant cardiovascular or respiratory changes in the anesthetized dog. Thus, HP 818 is potentially an effective presurgical medication due to its nonnarcotic analgesic activity and sedative neuroleptic effects, along with its lack of limiting cardiorespiratory side effects. 相似文献