全文获取类型
收费全文 | 12136篇 |
免费 | 831篇 |
国内免费 | 98篇 |
专业分类
耳鼻咽喉 | 116篇 |
儿科学 | 290篇 |
妇产科学 | 428篇 |
基础医学 | 1568篇 |
口腔科学 | 413篇 |
临床医学 | 1101篇 |
内科学 | 2674篇 |
皮肤病学 | 206篇 |
神经病学 | 940篇 |
特种医学 | 487篇 |
外国民族医学 | 3篇 |
外科学 | 1945篇 |
综合类 | 306篇 |
一般理论 | 4篇 |
预防医学 | 628篇 |
眼科学 | 122篇 |
药学 | 620篇 |
1篇 | |
中国医学 | 47篇 |
肿瘤学 | 1166篇 |
出版年
2023年 | 75篇 |
2022年 | 129篇 |
2021年 | 350篇 |
2020年 | 190篇 |
2019年 | 256篇 |
2018年 | 323篇 |
2017年 | 223篇 |
2016年 | 273篇 |
2015年 | 316篇 |
2014年 | 395篇 |
2013年 | 504篇 |
2012年 | 824篇 |
2011年 | 805篇 |
2010年 | 456篇 |
2009年 | 410篇 |
2008年 | 663篇 |
2007年 | 735篇 |
2006年 | 625篇 |
2005年 | 619篇 |
2004年 | 605篇 |
2003年 | 515篇 |
2002年 | 519篇 |
2001年 | 353篇 |
2000年 | 347篇 |
1999年 | 351篇 |
1998年 | 151篇 |
1997年 | 144篇 |
1996年 | 119篇 |
1995年 | 83篇 |
1994年 | 95篇 |
1993年 | 84篇 |
1992年 | 168篇 |
1991年 | 161篇 |
1990年 | 125篇 |
1989年 | 152篇 |
1988年 | 100篇 |
1987年 | 127篇 |
1986年 | 88篇 |
1985年 | 72篇 |
1984年 | 74篇 |
1983年 | 46篇 |
1982年 | 29篇 |
1981年 | 33篇 |
1980年 | 29篇 |
1979年 | 46篇 |
1977年 | 22篇 |
1976年 | 35篇 |
1975年 | 25篇 |
1974年 | 29篇 |
1972年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
Levodopa is the most effective drug for treating Parkinson's disease. However, long-term use of levodopa is often complicated by significantly disabling fluctuations and dyskinesias negating its beneficial effects. Younger age of Parkinson's disease onset, disease severity, and high levodopa dose increase the risk of development of levodopa-induced dyskinesias (LID). The underlying mechanisms for LID are unclear though recent studies indicate the importance of pulsatile stimulation of striatal postsynaptic receptors in their pathogenesis. The non-human primates with MPTP-induced parkinsonism serve as a useful model to study dyskinesia. Once established, LID are difficult to treat and therefore efforts should be made to prevent them. The therapeutic and preventative strategies for LID include using a lower dosage of levodopa, employing dopamine agonists as initial therapy in Parkinson's disease, amantadine, atypical neuroleptics, and neurosurgery. LID can adversely affect the quality of life and increase the cost of healthcare. 相似文献
993.
994.
Salmonella can survive in soil for months to years; consequently, soil can be a preharvest source of contamination of produce. Elimination of Salmonella with natural products and processes such as essential oils is important to prevent infection among consumers. Essential oils (distilled extract from plants) have been mainly evaluated in liquid medium and foods in which minimum inhibitory concentration is determined. However, there are no reports describing the impact of essential oils in soil, especially organic soil. We evaluated essential oils for controlling Salmonella enterica serovars in organic soil. Two essential oils (cinnamaldehyde and eugenol), two bio-pesticides (Ecotrol and Sporan), and an organic acid (20% acetic acid) at 0.5%, 1.0%, 1.5%, and 2.0% were mixed with organic sandy soil and inoculated with six different serovars of S. enterica separately. Soils were incubated at room temperature, and samples obtained at 1, 7, and 28 days were enumerated to determine survival. The bactericidal effect of cinnamaldehyde was evident at 0.5%, 1.0%, 1.5%, and 2.0% and during all times of incubation. Overall, Salmonella Negev was the most sensitive strain to oils resulting in significant reductions compared with other strains. Increases in oil concentration resulted in further reduction of Salmonella with all oils used in the study. Up to six log reductions in Salmonella serovars Typhimurium, Negev, and Newport were found after 1 day when cinnamaldehyde, Ecotrol, eugenol, Sporan, or acetic acid was used at 2% level. This study shows the potential use of essential oils to effectively reduce Salmonella populations in soil. The significant reduction of Salmonella could greatly reduce potential contamination of fresh organic produce inadvertently contaminated by soil. 相似文献
995.
B J Zheng S K Lo J S Tam M Lo C Y Yeung M H Ng 《Journal of clinical microbiology》1989,27(9):2083-2090
We determined titers of group A rotavirus common antibodies and neutralizing antibodies against serotypes 1 to 4 of prototype human rotavirus (HRV) in cord blood and serum specimens obtained from 38 infants at 4-month intervals from birth until 2 years of age. Nineteen of the infants developed one episode of HRV diarrhea each, and they were matched by age and birth weight with the other 19 infants, who did not develop HRV diarrhea during the follow-up period. We estimated the incidence rate of HRV infection for the two groups of infants combined to be a minimum of 1.34 episodes per infant per year, which is 22 times more common than the occurrence of overt disease caused by the virus in this community. The infection occurred constantly throughout the first 2 years of infancy, whereas all but one of the 19 episodes of overt disease occurred before 12 months of age. Seven of these overt episodes were preceded by at least one episode of subclinical infection earlier, and the other seven were probably due to primary HRV infection. The remaining five episodes occurred before 4 months of age, so that we could not ascertain whether they were due to primary infections because of the presence of maternal antibodies. We showed that levels of HRV antibodies in serum specimens obtained before clinical onset of diarrhea varied widely, and, for most infants in the diarrheal group, levels of these antibodies were similar to those in the serum specimens obtained at the same times from the corresponding age- and birth weight-matched control infants. Nevertheless, the age at which overt disease caused by HRV was most prevalent coincided with the time when the maternal antibodies had declined to low levels but the infants had not yet acquired high titers of these antibodies in their sera. 相似文献
996.
997.
The influence of ethnicity on the outcome of simultaneous kidney-pancreas transplantation (SKPT) is controversial. The aim of this study was to determine the impact of ethnicity on the major endpoints of a prospective, multicenter, randomized trial of two dosing regimens of daclizumab compared to no-antibody induction in SKPT. A total of 297 patients were randomized into three groups: daclizumab 1 mg/kg/dose every 14 days for five doses (group I, n = 107); daclizumab 2 mg/kg/dose every 14 days for two doses (group II, n = 112), and no-antibody induction (group III, n = 78). All patients received tacrolimus, mycophenolate mofetil, and steroids for maintenance immunosuppression. Thirty-seven patients (12.5%) were African-American (AA) and 260 were non-African-American (NAA). Demographics and transplant characteristics were comparable between AA and NAA patients. At 1 year, no differences were seen in patient survival (97% AA, 96% NAA), kidney graft survival (94% AA, 93% NAA), and pancreas graft survival (84% AA, 85% NAA). Rejection rate and incidence of adverse events were similar between AA and NAA subjects. Kidney graft function was comparable between AA and NAA patients at 1 year; however, mean HgbA1C was higher, C-peptide was lower, and oral hypoglycemic use was more common in AA subjects. Thus, in this prospective multicenter study, AA ethnicity was not associated with an increased risk of early adverse outcomes in SKPT. Follow-up will be required to determine whether long-term outcomes remain equivalent, particularly with regard to pancreas graft function. 相似文献
998.
Circulating fetal DNA in maternal plasma. 总被引:4,自引:0,他引:4
L L Poon Y M Lo 《Clinica chimica acta; international journal of clinical chemistry》2001,313(1-2):151-155
BACKGROUND: The existence of high concentrations of circulating fetal DNA in maternal plasma may enable non-invasive prenatal diagnosis. There are many applications of fetal DNA in maternal plasma for clinical diagnosis. CONCLUSIONS: We expect fetal DNA in material plasma will be incorporated into past of the prenatal investigation of pregnant women in the near future. 相似文献
999.
The students of Centre des Oeuvres Universitaires de Dakar (COUD) do not seem to participate to the management of their own health status in spite of their financial participation in some services. The aim of this study is to evaluate the students's participation in their own health status. The results obtained from documents and archives, COUD'S responsible and student's opinion have shown a financial participation of 8% from the COUD medical service budget. The students wish to participation actively to the management of the medical service while COUD's responsible have opposite opinion. For an efficiency management of their own health status, students must necessary participate. 相似文献
1000.
Selective detection of Mycoplasma fermentans by polymerase chain reaction and by using a nucleotide sequence within the insertion sequence-like element. 下载免费PDF全文
A new assay using the polymerase chain reaction to amplify a 206-nucleotide specific gene sequence within the insertion sequence-like element of Mycoplasma fermentans has been developed. The unique insertion sequence-like element exists in multiple copies in the M. fermentans genome. The assay selectively amplifies DNA from all strains of M. fermentans tested. In contrast, DNA from other species of human and nonhuman mycoplasmas, common tissue culture-contaminating mycoplasmas, and bacteria, as well as human, monkey, and mouse tissues do not produce the amplified DNA products specific for M. fermentans. 相似文献