全文获取类型
收费全文 | 3283333篇 |
免费 | 275517篇 |
国内免费 | 14181篇 |
专业分类
耳鼻咽喉 | 44930篇 |
儿科学 | 100447篇 |
妇产科学 | 83897篇 |
基础医学 | 523342篇 |
口腔科学 | 88778篇 |
临床医学 | 294776篇 |
内科学 | 572734篇 |
皮肤病学 | 86826篇 |
神经病学 | 285393篇 |
特种医学 | 129830篇 |
外国民族医学 | 207篇 |
外科学 | 512698篇 |
综合类 | 103674篇 |
现状与发展 | 24篇 |
一般理论 | 2421篇 |
预防医学 | 278495篇 |
眼科学 | 75448篇 |
药学 | 226381篇 |
25篇 | |
中国医学 | 9384篇 |
肿瘤学 | 153321篇 |
出版年
2021年 | 56029篇 |
2020年 | 35699篇 |
2019年 | 59004篇 |
2018年 | 71960篇 |
2017年 | 54812篇 |
2016年 | 60538篇 |
2015年 | 74803篇 |
2014年 | 109520篇 |
2013年 | 175173篇 |
2012年 | 96126篇 |
2011年 | 95632篇 |
2010年 | 117742篇 |
2009年 | 122005篇 |
2008年 | 81392篇 |
2007年 | 84786篇 |
2006年 | 95434篇 |
2005年 | 91006篇 |
2004年 | 92702篇 |
2003年 | 83229篇 |
2002年 | 72145篇 |
2001年 | 84726篇 |
2000年 | 76757篇 |
1999年 | 80654篇 |
1998年 | 63773篇 |
1997年 | 62065篇 |
1996年 | 59708篇 |
1995年 | 55176篇 |
1994年 | 49510篇 |
1993年 | 46275篇 |
1992年 | 57708篇 |
1991年 | 54897篇 |
1990年 | 52084篇 |
1989年 | 51671篇 |
1988年 | 48450篇 |
1987年 | 47373篇 |
1986年 | 45172篇 |
1985年 | 45768篇 |
1984年 | 43840篇 |
1983年 | 40476篇 |
1982年 | 40512篇 |
1981年 | 38345篇 |
1980年 | 36238篇 |
1979年 | 37048篇 |
1978年 | 33688篇 |
1977年 | 30960篇 |
1976年 | 28175篇 |
1975年 | 26667篇 |
1974年 | 27807篇 |
1973年 | 26718篇 |
1972年 | 25152篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Restriction fragment length polymorphism of human mitochondrial DNA in a sample population from Apulia (Southern Italy) 总被引:8,自引:1,他引:7
Restriction fragment length polymorphism (RFLP) of human mitochondrial DNA was analysed in a sample of 87 subjects from Apulia (South Italy) by the restriction enzymes Hpa I, Bam HI, Hae II, Msp I, Ava II, and Hinc II using total blood cell DNA probed by human mtDNA from placenta. Five BamHI morphs were observed, two of which are new ( Bam HI-4 and -5), as well as one new Ava II morph ( Ava II-28). The association Bam HI-4/ Ava II-28 enables us to demonstrate for the first time two polymorphic Bam HI sites present together in the same mtDNA molecule. In agreement with historical data the Apulian sample has been shown to be the most heterogeneous Italian population so far tested. 相似文献
992.
Department of Biology, Izhevsk Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR D. S. Sarkisov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 107, No. 3, pp. 353–356, March, 1989. 相似文献
993.
J M Debets R Kampmeijer M P van der Linden W A Buurman C J van der Linden 《Critical care medicine》1989,17(6):489-494
Tumor necrosis factor (TNF) cachectin has been implicated as an important host mediator responsible for shock and multiple organ failure (MOF) observed during sepsis. Using a sensitive enzyme-linked immunosorbent assay, we measured plasma TNF levels in 43 septic patients suffering from a broad range of diseases. Measurements were taken on the day that sepsis was diagnosed. Eleven patients had detectable TNF plasma levels ranging from 10 to 100 pg/ml (TNF-positive group); in 32 patients circulating TNF could not be detected (TNF-negative group). The groups did not differ significantly as to age, underlying disease, percentage positive bacteremia and bacteriologic profile, sepsis score, and extent of MOF. Eight (73%) of 11 TNF-positive patients died from sepsis during ICU stay, vs. 11 (34%) of 32 TNF-negative patients (p less than .05). This study demonstrates that sepsis is accompanied by detectable circulating TNF in 25% of the cases, and for these patients mortality is twice that for comparable TNF-negative patients. 相似文献
994.
In 1981 a statewide program supplying free insulin to 3,720 patients of state health clinics was discontinued. We attempted to assess whether this action had an adverse effect medically and financially on those concerned. A computer randomized sample of 351 patients (9%) was studied by personal interview and questionnaire. Information obtained focused on certain events that occurred 18 months before and after the program ceased. Measurements used to determine medical impact were number of hospitalizations, emergency room and physician visits, changes in weight and glucose levels, and episodes of ketoacidosis. Financial impact was measured by cost of hospitalization and physician visits. Our results revealed no significant changes in any of the medical parameters studied except for fasting serum glucose levels above 300 mg/dl, which occurred less frequently after the free insulin program was discontinued. There were fewer hospitalizations, more visits to physicians, and no change in number of emergency room visits after discontinuance of the free program. The overall cost saving was estimated to be +883,558 for the 18-month study period, in addition to the +550,000 the plan had been costing the state. 相似文献
995.
The aqueous, organic, and volatile oil extracts of leaves of Eugenia uniflora Linn. Family Myrtaceae were investigated for antibacterial properties using agar dilution techniques. The aqueous extract was the most active against the organisms compared to the organic and volatile oil extracts. The extracts were found to inhibit Gram positive Staphylococcus aureus and Bacillus subtilis and Gram negative Escherichia coli and Shigella dysentcriae. Pseudomonas aeruginosa, Klebsiella pneumoniac, and Salmonella typhi were not inhibited. 相似文献
996.
The in vitro ability of bacterial purified antigenic fractions to interfere with the immune system has been investigated on human mononuclear cells from peripheral blood. Exposure of purified monocytes to the drug at concentrations from 1 to 1000 micrograms/ml, for different periods from 0 to 18 h, significantly increased cell-mediated cytotoxicity against TU5 target cells. Moreover, monocytes exposed for 1 to 18 h to drug concentrations from 0.1 to 1000 micrograms/ml released significant amounts of tumor necrosis factor alpha in a dose-dependent manner in the culture supernatants. The drug was also tested on natural killer (NK) cell activity; mononuclear cells exposed to antigenic fractions for different periods showed a significant increase of NK cytotoxic activity against K562 target cells after 3 and 6, but not 0 and 18 h. Active concentrations were from 1 to 100 micrograms/ml, higher and lower doses being ineffective. Bacterial purified antigenic fractions thus have some ability to interfere in vitro with mechanisms of cytolysis mediated by cells and soluble factors. 相似文献
997.
Summary Split or full thickness eyelid defects resulting from tumor destruction or surgical excision present a dilemma for plastic and reconstructive surgeons. Full thickness eyelid replacement requires composite grafting of the skin, together with tarsal support of its substitute and mucosa. The flap described by Fricke in 1829 was used for reconstruction of anterior lamella in six lower eyelid defects. In three of our cases chondromucosal grafts taken from nasal septum were utilized for posterior lamella repair. The results have been satisfactory from a functional and cosmetic standpoint. 相似文献
998.
999.
1000.
The administration of prophylactic antibiotics in surgery is appropriate for many patients. Data have shown extending the duration of prophylaxis beyond 48 hours does not lower the rate of postoperative-infection. The purpose of this project was to concurrently assess the duration of prophylactic antibiotic use. A total of 95 patients were monitored over 3 weeks. Eighty patients (84.2%) received antimicrobial therapy. In 23 of these patients (28.75%) the duration of antibiotic administration was longer than 2 days without clinical or microbiological evidence of infection. In 5 other patients only postoperative antibiotics were prescribed. The cost difference between the actual duration of antibiotic administration and 2 days of the same regimen was +1,364.58. Extrapolating for one year, it can be estimated that antibiotic costs could be reduced about +23,600. Pharmacists can focus on the duration of antibiotic prophylaxis as a cost containment measure. 相似文献