全文获取类型
收费全文 | 847篇 |
免费 | 71篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 5篇 |
儿科学 | 33篇 |
妇产科学 | 6篇 |
基础医学 | 148篇 |
口腔科学 | 15篇 |
临床医学 | 109篇 |
内科学 | 135篇 |
皮肤病学 | 13篇 |
神经病学 | 72篇 |
特种医学 | 23篇 |
外科学 | 76篇 |
综合类 | 24篇 |
预防医学 | 103篇 |
眼科学 | 41篇 |
药学 | 70篇 |
中国医学 | 2篇 |
肿瘤学 | 45篇 |
出版年
2022年 | 6篇 |
2021年 | 8篇 |
2019年 | 9篇 |
2018年 | 7篇 |
2017年 | 11篇 |
2016年 | 12篇 |
2015年 | 16篇 |
2014年 | 24篇 |
2013年 | 40篇 |
2012年 | 41篇 |
2011年 | 44篇 |
2010年 | 22篇 |
2009年 | 27篇 |
2008年 | 35篇 |
2007年 | 40篇 |
2006年 | 33篇 |
2005年 | 40篇 |
2004年 | 35篇 |
2003年 | 41篇 |
2002年 | 29篇 |
2001年 | 16篇 |
2000年 | 16篇 |
1999年 | 17篇 |
1998年 | 18篇 |
1997年 | 18篇 |
1996年 | 9篇 |
1995年 | 13篇 |
1993年 | 15篇 |
1992年 | 15篇 |
1991年 | 14篇 |
1990年 | 16篇 |
1989年 | 14篇 |
1988年 | 9篇 |
1987年 | 12篇 |
1986年 | 5篇 |
1984年 | 8篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 11篇 |
1977年 | 9篇 |
1976年 | 8篇 |
1973年 | 5篇 |
1972年 | 5篇 |
1971年 | 6篇 |
1969年 | 5篇 |
1963年 | 8篇 |
1947年 | 4篇 |
1944年 | 6篇 |
1930年 | 4篇 |
排序方式: 共有920条查询结果,搜索用时 31 毫秒
51.
The National Kidney Foundation and the European Renal Association recommend routine measurement of hemodialysis (HD) dose and have set standards for adequacy of treatment. We compare the results of five methods for HD dose estimation, classifying each result as adequate or inadequate on the basis of equilibrated (eq) Urea Reduction Ratio (URR(eq)) > or = 65% or Kt/V(eq) > or = 1.2, to assess the accuracy of each method as a diagnostic tool. Data from 113 patients from two different dialysis units were analyzed. Equilibrated postdialysis blood urea was measured 60 min after each hemodialysis session to calculate URR(eq) and Kt/V(eq), considered as gold standard indexes (GSI). URR and Kt/V were estimated by using the Smye formula, an artificial neural network (ANN), modified URR, the second generation Kt/V Daugirdas formula, and standard indexes based on postdialysis urea, then compared to the GSI. For URR, best estimator was ANN (error rate: ER% = 12.70), followed by modified URR (ER% = 17.46%), the Smye (ER% = 22.22), and standard URR (ER% = 23.81). For Kt/V, the Daugirdas equation and the ANN were similar (ER% = 9.52 and 11.11). The single-pool Kt/V (Kt/V(sp)) > or = 1.4 (ERA recommended) produced an ER% = 7.94 and a false positive rate (FPR%) equal to that shown by the ANN (FPR% = 3.17). According to the current threshold limits for HD dose adequacy, the ANN was a reliable and accurate tool for URR monitoring, better than the Smye and the modified URR methods. The use of the ANN urea estimation yields accurate results when used to calculate Kt/V. The Kt/V(sp) with an adequacy threshold of 1.4 is a superior approach for HD adequacy monitoring, suggesting that the current adequacy limits should be reviewed for both URR and Kt/V. 相似文献
52.
53.
A number of studies have been devoted to the examination of clear versus conversational speech in non-impaired speakers. The purpose of these previous studies has been primarily to help increase speech intelligibility for the benefit of hearing-impaired listeners. The goal of the present study was to examine differences between conversational and clear speech in individuals with Parkinson disease (PD). Twelve individuals were recorded producing conversational and clear speech. Acoustic analysis revealed that individuals with PD used some of the same clear speech strategies used by non-impaired speakers. Specifically, clear speech in PD was characterized by decreased articulation rate, increased mean fundamental frequency (F(o)), and increased speaking F(o)S.D. compared to conversational speech. The discussion examines the possibility that individuals with PD may have been independently applying a clear speech strategy based on their habitually increased percent pause values. Discussion also focuses on implications of the present findings to management of individuals with PD, and research implications. LEARNING OUTCOMES: As a result of this activity, the participant will be able to (1) describe the characteristics of clear speech produced by non-disordered individuals, (2) describe the acoustic characteristics of clear and conversational speech produced by individuals with Parkinson disease; and (3) describe the strategies individuals with Parkinson disease use when asked to produce clear speech. 相似文献
54.
55.
López-Meza E Ruiz-Chow A Ramirez-Bermudez J 《The Journal of neuropsychiatry and clinical neurosciences》2005,17(3):421-422
Aripiprazole is an agent for treating schizophrenia. The authors assume that aripiprazole as a dopamine receptor partial agonist may be useful in treating PD patients. Three cases are presented in this study. All patients were evaluated by the same clinician, a neuropsychiatrist well trained in the use of Brief Psychiatric Rating Scale (BPRS) and Clinical Global Impression (CGI). Aripiprazole was effective for reducing psychosis in each case. 相似文献
56.
Mead DG Gray EW Noblet R Murphy MD Howerth EW Stallknecht DE 《Journal of medical entomology》2004,41(1):78-82
The role of hematophagous arthropods in vesicular stomatitis virus (New Jersey serotype; VSV-NJ) transmission during epizootics has remained unclear for decades in part because it has never been shown that clinical or subclinical disease in a livestock host results from the bite of an infected insect. In this study, we investigated the ability of VSV-NJ-infected black flies (Simulium vittatum Zetterstedt) to transmit the virus to domestic swine, Sus scrofa L. Experimental evidence presented here clearly demonstrates that VSV-NJ was transmitted from black flies to the swine. Transmission was confirmed by seroconversion or by the presence of clinical vesicular stomatitis followed by seroconversion. Our results represent the first report of clinical vesicular stomatitis in a livestock host after virus transmission by an insect. 相似文献
57.
58.
59.
60.
Stephens MS Overmyer JP Gray EW Noblet R 《Journal of the American Mosquito Control Association》2004,20(2):171-175
Personnel from several black fly control programs have reported that the efficacy of Bacillus thuringiensis var. israelesis (Bti) is reduced during periods when algal concentrations are high in the waterways. Although the reduction in Bti-induced mortality in black fly larvae is presumed to be related to the presence of algae, no scientific data support this theory. In this study, 4 genera of algae (Microcytis, Scenedesmus, Dictrosphaerium, and Chlorella) commonly detected in Pennsylvania rivers where Bti-induced mortality in black fly larvae has been reduced were assessed to determine their respective effects on Bti-induced mortality by using an orbital shaker bioassay with laboratory-reared black fly larvae (Simulium vittatum cytospecies IS-7). A significant reduction in Bti-induced mortality was observed when Scenedesmus was present in the flasks at concentrations > or = 16,000 cells/ml. The Bti-induced mortality of larvae was not significantly reduced when Chlorella, Dictyosphaerium, or Microcytis was present in the flasks, even at concentrations > or = 250,000 cells/ml. These results indicate that the presence of certain types of algae can reduce the mortality of black flies exposed to Bti. Although not clearly defined, the mechanisms involved may be related to algal morphology due to overall size and structures associated with certain types of algae, and possible interference with feeding. 相似文献