全文获取类型
收费全文 | 61254篇 |
免费 | 6242篇 |
国内免费 | 131篇 |
专业分类
耳鼻咽喉 | 635篇 |
儿科学 | 1802篇 |
妇产科学 | 1492篇 |
基础医学 | 8830篇 |
口腔科学 | 1265篇 |
临床医学 | 7375篇 |
内科学 | 11292篇 |
皮肤病学 | 821篇 |
神经病学 | 6212篇 |
特种医学 | 2094篇 |
外国民族医学 | 57篇 |
外科学 | 7572篇 |
综合类 | 1104篇 |
一般理论 | 65篇 |
预防医学 | 7391篇 |
眼科学 | 1471篇 |
药学 | 4494篇 |
1篇 | |
中国医学 | 48篇 |
肿瘤学 | 3606篇 |
出版年
2023年 | 516篇 |
2022年 | 750篇 |
2021年 | 1605篇 |
2020年 | 949篇 |
2019年 | 1460篇 |
2018年 | 1609篇 |
2017年 | 1142篇 |
2016年 | 1218篇 |
2015年 | 1236篇 |
2014年 | 1703篇 |
2013年 | 2435篇 |
2012年 | 3358篇 |
2011年 | 3383篇 |
2010年 | 1859篇 |
2009年 | 1587篇 |
2008年 | 2801篇 |
2007年 | 2744篇 |
2006年 | 2611篇 |
2005年 | 2467篇 |
2004年 | 2423篇 |
2003年 | 2110篇 |
2002年 | 1996篇 |
2001年 | 1584篇 |
2000年 | 1693篇 |
1999年 | 1454篇 |
1998年 | 644篇 |
1997年 | 552篇 |
1996年 | 501篇 |
1995年 | 504篇 |
1994年 | 458篇 |
1993年 | 438篇 |
1992年 | 1130篇 |
1991年 | 1175篇 |
1990年 | 1073篇 |
1989年 | 1056篇 |
1988年 | 1052篇 |
1987年 | 928篇 |
1986年 | 922篇 |
1985年 | 898篇 |
1984年 | 748篇 |
1983年 | 610篇 |
1982年 | 407篇 |
1979年 | 700篇 |
1978年 | 551篇 |
1977年 | 453篇 |
1976年 | 431篇 |
1975年 | 402篇 |
1974年 | 464篇 |
1973年 | 452篇 |
1972年 | 399篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
33.
Introduction The associations between vitamin D receptor (VDR) Bsm I and Fok I genotypes, parity, and risk of osteoporotic hip fracture were evaluated in a statewide population-based case-control study in Utah.Methods Women age 50–89 years with hip fracture (n=882) were ascertained via surveillance of 18 Utah hospitals from 1997 to 2001. Age-matched controls were randomly selected (n=897). Participants were interviewed in their homes, and blood samples were collected for genotyping.Results In logistic regression analyses that controlled for multiple confounders, Bsm I VDR genotype but not Fok I genotype was associated with risk of osteoporotic hip fracture (OR bb vs. BB genotype: 0.68; 95% CI: 0.50, 0.95). In similar analyses, no overall association was observed between parity status and risk of osteoporotic hip fracture. However, the effect of VDR genotype was modified by parity status. Among nulliparous women (n=140), Bsm I genotype was not associated with risk of hip fracture (OR bb vs. BB: 0.82; 95% CI: 0.28, 2.4); among primiparous women (n=133), bb genotype was associated with increased risk of hip fracture (OR bb vs. BB: 3.30; 95% CI: 0.96, 11.29); among multiparous women (n=1,400), bb genotype was associated with decreased risk of hip fracture (OR bb vs. BB: 0.59; 95% CI: 0.42, 0.84).Conclusion VDR Bsm I genotype was associated with risk of hip fracture in Utah women, and this effect was modified by parity status. Hormonal or lifestyle factors related to parity may underlie this interaction. 相似文献
34.
Paul A Dabisch Emily A Davis Michael S Horsmon Robert J Mioduszewski 《Journal of ocular pharmacology and therapeutics》2006,22(5):323-332
The organophosphorous nerve agent sarin (GB) and the carbamate pyridostigmine bromide (PB) both inhibit acetylcholinesterase (AChE), leading to overstimulation of muscarinic receptors. Both GB and PB produce miosis through stimulation of ocular muscarinic receptors. This study investigated 2 hypotheses: (1) that the miotic response to PB would decrease following repeated injections; and (2) that repeated administration of PB would result in tolerance to the miotic effect of GB vapor. Rats were injected intramuscularly with saline, 0.04 mg/kg, 0.5 mg/kg, or 1.4 mg/kg of PB twice daily for 8 consecutive days. After day 3, animals injected with 1.4 mg/kg PB developed miotic tolerance. Twenty-four (24) h following the final PB injection, the rats were exposed to GB vapor (4.0 mg/m(3)). A similar magnitude of miosis was observed in all groups after GB exposure. However, the rate of recovery of pupil size in animals pretreated with 0.5 and 1.4 mg/kg PB was significantly increased. Twenty (20) h following exposure to GB vapor, the pupils of animals pretreated with 1.4 mg/kg PB had recovered to 77% +/- 4% of their pre-exposure baseline, whereas the saline-injected controls had recovered to only 52% +/- 2% of their pre-exposure baseline. The increased rate of recovery does not appear to be a result of protection of pupillary muscarinic receptors by the higher doses of PB, as there was no longer PB present in the animal at the time of GB exposure. These results demonstrate the development of tolerance to the miotic effect of PB following repeated exposures, and also suggest that cross-tolerance between PB and GB occurs. However, because the magnitude of the response was not reduced, the PB pretreatment and its associated miotic cross-tolerance does not appear to diminish the effectiveness of miosis as a biomarker of acute exposure to nerve agent vapor. 相似文献
35.
Esophageal foreign body causing direct aortic injury. 总被引:4,自引:0,他引:4
Foreign bodies in the esophagus are uncommon causes of esophageal perforation. Many nonperforating cases are successfully managed by flexible gastroscopy. However, complicated foreign bodies such as those that result in esophageal perforation and vascular injury are best managed surgically. Gastroscopy remains the primary method of diagnosis. A case of a 59-year-old woman who developed retrosternal and intrascapular pain, odynophagia and hematemesis after eating fish is reported. Flexible gastroscopy showed arterial bleeding from the midthoracic esophagus. Computed tomography scan localized a 3 cm fish bone perforating the esophagus with surrounding hematoma. An aortogram did not reveal an actively bleeding aortoesophageal fistula. The fish bone was surgically removed and the patient recovered with no postoperative complications. This case illustrates the importance of early consideration for surgical intervention when confronted with a brisk arterial bleed from the esophagus with suggestive history of foreign body ingestion. 相似文献
36.
P F Plouin D L Clement H Boccalon J Dormandy I Durand-Zaleski G Fowkes L Norgren T Brown 《International angiology》2003,22(4):333-339
Atherosclerotic renal artery stenosis (ARAS) may cause hypertension, progressive renal failure, and recurrent pulmonary edema. It typically occurs in high risk patients with coexistent vascular disease elsewhere. Most patients with ARAS are likely to die from coronary heart disease or stroke before end-stage renal failure occurs. Recent controlled trials have shown that most patients undergoing angioplasty to treat renovascular hypertension still need antihypertensive agents 6 or 12 months after the procedure. Nevertheless, the number of antihypertensive agents required to control blood pressure adequately is lower following angioplasty than for medication alone. Trials assessing the value of revascularization for preserving renal function or preventing clinical events are only in the early recruitment phase. Revascularization should be undertaken in patients with ARAS and resistant hypertension or heart failure, and probably in those with rapidly deteriorating renal function or with an increase in plasma creatinine levels during angiotensin-converting enzyme inhibition. With or without revascularization, medical therapy using antihypertensive, hypolipidemic and antiplatelet agents is necessary in almost all cases. 相似文献
37.
G. Kahlmeter D. F. J. Brown F. W. Goldstein A. P. MacGowan J. W. Mouton I. Odenholt A. Rodloff C-J. Soussy M. Steinbakk F. Soriano O. Stetsiouk 《Clinical microbiology and infection》2006,12(6):501-503
The main objectives of the European Committee on Antimicrobial Susceptibility Testing (EUCAST) are to harmonise breakpoints for antimicrobial agents in Europe, and to act as the breakpoint committee for the European Medicines Agency (EMEA) during the registration of new antimicrobial agents. Detailed EUCAST procedures for harmonising and setting breakpoints for antimicrobial agents are available on the EUCAST website. Beginning with the current issue, a series of EUCAST Technical Notes will be published in CMI, based on the rationale documents produced by EUCAST for each of the antimicrobial agents studied, with the aim of highlighting important background information underlying decisions on breakpoints made by EUCAST. 相似文献
38.
39.
K Brown 《Environmental health perspectives》1996,104(3):276-278
40.
Although extracellular matrix (ECM) glycoproteins play important roles in neural development, their levels are generally believed to decrease in the adult brain. Immunohistochemical analysis indicates that the anti-adhesive ECM glycoprotein SPARC/osteonectin, which contains a follistatin ‘module’, is expressed in the adult rabbit nervous system. In the cerebellum, SPARC is present in Bergmann glia, with a strong signal along their radial fibres. SPARC, while enriched in membrane fractions, is not a transmembrane protein. In the hippocampus, colocalization of SPARC is observed in cells which express the astrocytic marker GFAP. The expression of SPARC by a subset of astrocytes, particularly in synaptic enriched areas, suggests a continuing role for the ECM in the adult brain. 相似文献