全文获取类型
收费全文 | 35143篇 |
免费 | 2881篇 |
国内免费 | 137篇 |
专业分类
耳鼻咽喉 | 270篇 |
儿科学 | 862篇 |
妇产科学 | 509篇 |
基础医学 | 4619篇 |
口腔科学 | 870篇 |
临床医学 | 3786篇 |
内科学 | 7476篇 |
皮肤病学 | 439篇 |
神经病学 | 2963篇 |
特种医学 | 1250篇 |
外科学 | 5237篇 |
综合类 | 663篇 |
现状与发展 | 1篇 |
一般理论 | 26篇 |
预防医学 | 3192篇 |
眼科学 | 672篇 |
药学 | 2642篇 |
中国医学 | 79篇 |
肿瘤学 | 2605篇 |
出版年
2023年 | 286篇 |
2022年 | 500篇 |
2021年 | 1110篇 |
2020年 | 585篇 |
2019年 | 929篇 |
2018年 | 1052篇 |
2017年 | 752篇 |
2016年 | 793篇 |
2015年 | 911篇 |
2014年 | 1238篇 |
2013年 | 1623篇 |
2012年 | 2422篇 |
2011年 | 2525篇 |
2010年 | 1418篇 |
2009年 | 1181篇 |
2008年 | 1926篇 |
2007年 | 1951篇 |
2006年 | 1830篇 |
2005年 | 1819篇 |
2004年 | 1801篇 |
2003年 | 1664篇 |
2002年 | 1690篇 |
2001年 | 613篇 |
2000年 | 512篇 |
1999年 | 535篇 |
1998年 | 446篇 |
1997年 | 401篇 |
1996年 | 293篇 |
1995年 | 271篇 |
1994年 | 280篇 |
1993年 | 252篇 |
1992年 | 299篇 |
1991年 | 267篇 |
1990年 | 330篇 |
1989年 | 279篇 |
1988年 | 245篇 |
1987年 | 267篇 |
1986年 | 244篇 |
1985年 | 211篇 |
1984年 | 217篇 |
1983年 | 193篇 |
1982年 | 179篇 |
1981年 | 148篇 |
1980年 | 138篇 |
1979年 | 137篇 |
1978年 | 128篇 |
1977年 | 105篇 |
1976年 | 110篇 |
1975年 | 97篇 |
1973年 | 101篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
52.
Shafi Mussa Tash Prior Nicholas Alp Kathryn Wood Keith M Channon David P Taggart 《European journal of cardio-thoracic surgery》2004,26(5):988-994
OBJECTIVE: Radial arteries are increasingly used as conduits for coronary artery bypass grafts, but perioperative graft vasospasm remains a concern. In vitro testing has demonstrated the efficacy of phenoxybenzamine and verapamil/nitroglycerin as topical antispasmodic agents, but their duration of action in vivo is unknown. Using an in vivo mouse model, we measured their duration of action in functioning vascular grafts, and compared this to their in vitro duration of action in ungrafted vascular segments. METHODS: Two millimetre mouse aortic segments (C57/BL6) were incubated with phenoxybenzamine, verapamil/nitroglycerin, or buffer (controls) for 15 min in organ chambers. Isometric tension responses to phenylephrine and prostaglandin F2alpha were measured at 0, 2, 6 and 12 h post-incubation. In parallel, 36 murine infrarenal aortic interposition grafts (2 mm) were performed. Twelve grafts were pre-treated (15 min) with phenoxybenzamine, 12 with verapamil/nitroglycerin and 12 remained untreated (controls). Isometric tension responses to the same agonists were measured in grafts harvested 2, 6, 13 and 23 h after surgery. RESULTS: Phenoxybenzamine prevented alpha-adrenergic vasoconstriction for up to 16 h in vivo (grafts), and 12h in vitro (ungrafted segments). Verapamil/nitroglycerin was effective for at least 2 h in vitro, but did not prevent vasoconstriction after 2 h in vivo. CONCLUSIONS: The mouse model appears to be a useful technique for assessing the pharmacological properties of antispasmodic agents in vivo. Phenoxybenzamine has an extended action in arterial grafts in vivo. Verapamil/nitroglycerin is short-lived in vivo but lasts longer in vitro. Measurements of antispasmodic duration of action in vitro should be interpreted with caution. 相似文献
53.
Cesar G. Victora Nubia Muoz Nicholas E. Day Lucio B. Barcelos Debora A. Peccin Noris M. Braga 《International journal of cancer. Journal international du cancer》1987,39(6):710-716
There is a cluster of high-incidence areas of oesophageal cancer in south-eastern South America, including Southern Brazil, Uruguay and parts of Argentina. The present case-control study investigated the hypothesis that this may be due to the drinking of maté, a traditional beverage drunk at a very high temperature, and also studied the role of other known risk factors such as alcohol and tobacco. Cases (171) and age- and sex-matched controls (342) were recruited from hospitals in the State of Rio Grande do Sul in Southern Brazil. The crude odds ratio for daily maté drinkers was 1.92 relative to those drinking less frequently than daily (p = 0.006). Other risk factors included the drinking of cachaça (a sugar cane spirit), smoking, rural residence, low fruit consumption and high intake of meats. After adjustment for these variables through conditional logistic regression, the odds ratio associated with daily maté drinking was reduced to 1.47 (90% CI = 0.87 - 2.50). Although the study failed to provide evidence of a strong association between maté and oesophageal cancer, the cluster of high rates could be explained by relative risks of the magnitude observed. This is due to the fact that approximately 70% of adult males and 50% of females are daily drinkers. In addition, this study revealed that alcohol, tobacco smoking and rural residence are the main risk factors for oesophageal cancer in this population and the fruit consumption confers some degree of protection. 相似文献
54.
Eighteen neonates ranging in birthweight from 820 to 1570 gm and in gestational age from 29 to 35 weeks were assigned alternately and blindly to feedings with formulas containing 14 or 50% of their fat as medium-chain triglycerides (MCT). Mean daily intakes of formula and mean daily weight gains were similar in neonates in the two groups. Consistency of stools and mean weekly increments in skinfold thickness were not affected by the MCT content of the formula. This suggests that under ordinary clinical conditions, medium-chain triglycerides exert no laxative effect nor affect adversely the deposition of subcutaneous fat in very low-birthweight neonates. 相似文献
55.
Robert Estes Daniel Estes Constance West Jitka Zobal-Ratner Patrick Droster John Simon 《Journal of AAPOS》2007,11(4):325-329
PURPOSE: To describe data sources and functional utility of the American Association for Pediatric Ophthalmology and Strabismus (AAPOS) workforce database and associated map files. METHODS: Population data from the 2000 U.S. Census and current listings from the AAPOS and American Academy of Ophthalmology (AAO) databases were organized to demonstrate and analyze practitioner-to-population relationships for metropolitan statistical areas nationwide. An interactive map was developed to provide an intuitive graphical display of the data. RESULTS: A total of 749 active AAPOS members were distributed in 154 of 280 defined metropolitan statistical areas. Within these areas, a 0- to 20-year age subgroup varied from 17.8% to 42.6%, with an average of 30.4%. The AAPOS member-to-million-person ratio varied from 1.3 to 27, with higher numbers generally representing regions with population bases inadequately defined by Census Bureau statistical area definitions. Ratios for a majority of larger, better-defined areas ranged from 3 to 4 AAPOS members per million persons. Sizable areas with no AAPOS member presence were identified and tabulated. AAO members with a specified pediatric practice focus who were not AAPOS members were identified in 103 areas, possibly influencing patient choices and practitioner referrals for these regions. CONCLUSIONS: The AAPOS workforce database and related interactive map display practitioner and population data that may assist physicians and planners in targeting practice development and identifying potentially underserved areas. 相似文献
56.
Effects of Ethanol Exposure during the Third Trimester Equivalent on Neuron Number in Rat Hippocampus and Dentate Gyrus 总被引:5,自引:0,他引:5
James R. West PhD Kristin M. Hamre BA Martin D. Cassell PhD 《Alcoholism, clinical and experimental research》1986,10(2):190-197
An artificial rearing procedure was used to expose neonatal rats to a formula containing 3.74% ethanol during postnatal days 4 through 10. This treatment produced a mean blood ethanol concentration of 379.8 +/- 17.3 mg/dl. When the pups were killed on the afternoon of postnatal day 10, brain weight to body weight ratio in the ethanol-exposed rats was reduced 22.4% and 21.5% compared to suckle and pair-fed controls, respectively. Ethanol exposure also resulted in a 16% reduction of neurons in hippocampal field CA4, compared to controls, but did not produce deficits in fields CA1 or CA3. There was also a 10% increase in the number of neurons (a population of cells in the midst of a proliferative phase at the time of the exposure) in the granule cell layer of the dentate gyrus. The ethanol exposure did not affect cell size in any of the four neuron populations measured. These results suggest, that within the dose and timing parameters examined, ethanol exposure during the third trimester equivalent appears to be preferentially harmful to specific populations of developing neurons. 相似文献
57.
58.
Noel R. Fajardo Filippo Cremonini Dr Nicholas J. Talley 《American Journal of Cancer》2006,5(5):319-330
In patients with cancer, constipation is a common complication. However, unlike in the general population, the impact of the symptoms of constipation on the quality of life in cancer patients is often greater. More importantly, in patients who are in the more advanced stages of the disease, constipation may also be suggestive of disease progression. Constipation as a symptom in this population is of significant importance as it may lead to life-threatening complications, i.e. bowel perforation due to fecal impaction. Therefore, in this regard, this problem deserves particular attention, as early recognition and management of complications may prevent further physical deterioration. This review aims to provide an overview of the management of constipation in patients with cancer. A symptom-based criteria definition for chronic constipation and prevalence of the problem in cancer patients provides a brief introduction. For the initial assessment and evaluation of constipation in cancer patients, an algorithm is described. The different possible etiologies of constipation in cancer patients are also discussed. Regarding therapeutic management, guidelines and recommendations for the use of different types of laxatives, stool softeners, suppositories and rectal enemas, prokinetic agents, antidepressant medications, and miscellaneous agents are succinctly discussed. Management of fecal impaction and opioid-induced bowel dysfunction are also described. Lastly, a brief overview of the management of acute colonic pseudo-obstruction and surgical or endoscopic options for large bowel obstruction are described. 相似文献
59.
60.