全文获取类型
收费全文 | 4681篇 |
免费 | 462篇 |
国内免费 | 7篇 |
专业分类
耳鼻咽喉 | 39篇 |
儿科学 | 117篇 |
妇产科学 | 78篇 |
基础医学 | 667篇 |
口腔科学 | 62篇 |
临床医学 | 608篇 |
内科学 | 942篇 |
皮肤病学 | 119篇 |
神经病学 | 460篇 |
特种医学 | 184篇 |
外科学 | 535篇 |
综合类 | 63篇 |
一般理论 | 1篇 |
预防医学 | 631篇 |
眼科学 | 62篇 |
药学 | 279篇 |
中国医学 | 5篇 |
肿瘤学 | 298篇 |
出版年
2023年 | 59篇 |
2022年 | 43篇 |
2021年 | 121篇 |
2020年 | 92篇 |
2019年 | 143篇 |
2018年 | 144篇 |
2017年 | 106篇 |
2016年 | 108篇 |
2015年 | 129篇 |
2014年 | 161篇 |
2013年 | 160篇 |
2012年 | 335篇 |
2011年 | 303篇 |
2010年 | 153篇 |
2009年 | 104篇 |
2008年 | 233篇 |
2007年 | 223篇 |
2006年 | 202篇 |
2005年 | 243篇 |
2004年 | 222篇 |
2003年 | 197篇 |
2002年 | 197篇 |
2001年 | 105篇 |
2000年 | 94篇 |
1999年 | 77篇 |
1998年 | 40篇 |
1997年 | 30篇 |
1996年 | 47篇 |
1995年 | 34篇 |
1994年 | 45篇 |
1993年 | 39篇 |
1992年 | 85篇 |
1991年 | 79篇 |
1990年 | 68篇 |
1989年 | 70篇 |
1988年 | 53篇 |
1987年 | 52篇 |
1986年 | 60篇 |
1985年 | 61篇 |
1984年 | 40篇 |
1983年 | 32篇 |
1982年 | 29篇 |
1981年 | 26篇 |
1980年 | 33篇 |
1979年 | 26篇 |
1975年 | 15篇 |
1974年 | 21篇 |
1973年 | 14篇 |
1970年 | 15篇 |
1967年 | 14篇 |
排序方式: 共有5150条查询结果,搜索用时 203 毫秒
1.
Paula Cristina Galati Paula Garcia Chiarello Belinda Pinto Simões 《Nutrition and cancer》2016,68(1):86-93
Changes in resting energy expenditure (REE) of cancer patients vary depending on type of tumor, treatment time point and kind of treatment. Little is known about REE of acute leukemia adult patients after treatment, especially with results related to body weight or fat free mass (FFM). This study aimed to assess changes in REE of acute leukemia adult patients before and after the first remission induction. Evaluation of REE was performed by indirect calorimetry and predicted REE was calculated by Harris-Benedict equation. Weight and height were measured and compared to a control group of healthy individuals. FFM was assessed by bioelectrical impedance for adjusting REE values. We evaluated 18 patients and 26 healthy individuals. At diagnosis, patients presented REE, REE/weight, and REE/FFM higher than the controls. Reductions of REE, REE/weight, and REE/FFM were also observed in patients after the first cycle of chemotherapy. The predicted REE for the patients group showed significant lower value compared with measured REE. Before the first cycle of chemotherapy REE was increased but undergoes a reduction after treatment, reaching values similar to the controls. For predictive Harris-Benedict equation, stress factors should be added to avoid underestimation of REE before and after chemotherapy. 相似文献
2.
The use of bacterins is one of the primary methods in the control of leptospirosis in domestic animals, especially cattle, swine, and dogs. Bacterins have been made using chemically treated or heat-inactivated organisms. Many of the initial studies indicated that the bacterins gave complete protection, whereas later reports found that some inactivation methods resulted in bacterins that protect against death but not against kidney infection and renal shedding. This raised the possibility that some of the antigens had been altered. To investigate this possibility, we heat or chemically treated Leptospira interrogans serovar icterohaemorrhagiae CF-1, L. interrogans serovar canicola Moulton, L. interrogans serovar grippotyphosa SC4397, L. interrogans serovar hardjo Hardjoprajitno, and L. interrogans serovar pomona MLS. Temperatures used to determine alterations in antigens were 50, 56, 80, 100, and 121 degrees C. The chemicals used were formaldehyde, phenol, and thimerosal. Analysis was done using Laemmli gels and Western blots. We found that heating at 50 or 56 degrees C had the smallest effect on antigens, whereas heating at 80 or 100 degrees C caused the appearance of high-molecular-weight bands on Western blots. Heating at 121 degrees C caused almost all the bands to disappear, in both the stained gel and the Western blot. Both phenol and Formalin treatment altered proteins, whereas thimerosal treatment appeared to have little effect compared with heating at 50 degrees C. 相似文献
3.
The morphological and functional changes in rat bladder following photodynamic therapy with phthalocyanine photosensitization 总被引:2,自引:0,他引:2
We have studied photodynamic therapy (PDT) in the rat bladder with a new photosensitizer, aluminium sulfonated phthalocyanine (AlSPc) given intravenously and intravesically. The microscopic distribution of photosensitizer fluorescence in the bladder wall was studied by laser fluorescence microscopy. Prior to PDT the bladder capacity and compliance were assessed by filling cystometry. Intravesical red light (675 nm.) from a copper vapour pumped dye laser was used to activate the photosensitizer using light doses of 20 to 200 J/cm2. Urodynamic and histologic changes were studied at intervals for up to three months. The fluorescence studies showed that AlSPc was eliminated from the deeper muscle layers more quickly than from the superficial layers of the bladder wall so that by 24 hours there was four times as much fluorescence from the mucosa and lamina propria compared to the deeper muscle. Control bladders illuminated with laser light alone showed no effects at these light doses. Animals treated 24 hours after sensitization showed a reduction in bladder capacity of up to 78% (20 J/cm2. light and 1.5 mg./kg.AlSPc). An initial reduction in compliance recovered in two weeks after low doses (0.5 mg./kg.) of AlSPc but was still abnormal at three months after higher doses (1.5 mg./kg.); though there was no long term histologic abnormality seen. Aluminium sulfonated phthalocyanine is a promising photosensitizer for bladder photodynamic therapy and using low doses of the drug it is possible to produce a superficial necrosis without muscle damage across a range of light doses. This heals by epithelial regeneration with no long term functional impairment. Direct absorption of this photosensitizer following intravesical administration seems unreliable. 相似文献
4.
5.
Scalp electrical recording during paralysis: quantitative evidence that EEG frequencies above 20 Hz are contaminated by EMG. 总被引:2,自引:0,他引:2
Emma M Whitham Kenneth J Pope Sean P Fitzgibbon Trent Lewis C Richard Clark Stephen Loveless Marita Broberg Angus Wallace Dylan DeLosAngeles Peter Lillie Andrew Hardy Rik Fronsko Alyson Pulbrook John O Willoughby 《Clinical neurophysiology》2007,118(8):1877-1888
OBJECTIVE: To identify the possible contribution of electromyogram (EMG) to scalp electroencephalogram (EEG) rhythms at rest and induced or evoked by cognitive tasks. METHODS: Scalp EEG recordings were made on two subjects in presence and absence of complete neuromuscular blockade, sparing the dominant arm. The subjects undertook cognitive tasks in both states to allow direct comparison of electrical recordings. RESULTS: EEG rhythms in the paralysed state differed significantly compared with the unparalysed state, with 10- to 200-fold differences in the power of frequencies above 20 Hz during paralysis. CONCLUSIONS: Most of the scalp EEG recording above 20 Hz is of EMG origin. Previous studies measuring gamma EEG need to be re-evaluated. SIGNIFICANCE: This has a significant impact on measurements of gamma rhythms from the scalp EEG in unparalysed humans. It is to be hoped that signal separation methods will be able to rectify this situation. 相似文献
6.
7.
Belinda Joy Deal Rebecca A Fountain Carol Ann Russell-Broaddus Melinda Stanley-Hermanns 《Disaster Management & Response》2006,4(4):100-105
Hurricanes Katrina and Rita forced many individuals along the coast of Texas and Louisiana to seek shelter inland. Among the evacuees were residents with special needs and residents of nursing homes and group homes caring for mentally retarded and physically disabled persons. Many nurses volunteered to provide health care for those in need. This article discusses challenges and opportunities that were encountered by nurses volunteering in special-needs shelters. Issues related to human and physical resources, patient care, and confidentiality are discussed including lessons learned. As nurses who cared for evacuees in the shelter, it is hoped some of the lessons learned can be utilized in future disasters. 相似文献
8.
Tears of the retinal pigment epithelium (RPE) are a recognized complication of pigment epithelium detachments associated with age-related macular degeneration (ARMD). The RPE tears are often associated with a poor visual prognosis and typically do not occur with subretinal hemorrhage. We report the case of a 76-year-old man with ARMD who developed an RPE tear associated with subretinal hemorrhage, without a demonstrable subretinal neovascular membrane. Temporally, there was a marked decrease in his vision that returned to his earlier baseline visual acuity over the course of six months of observation. 相似文献
9.
Studies were done to determine the mechanism(s) responsible for the thermal lability of adrenal microsomal monooxygenases. Preincubation of guinea pig adrenal microsomal suspensions at 37 degrees C caused large time-dependent declines in benzo(a)pyrene (BP) hydroxylase and benzphetamine (BZ) demethylase activities. Similar preincubations with hepatic microsomes had little effect on enzyme activities. The decreases in adrenal enzyme activities were completely prevented by co-incubation of microsomes with cytosol, but were not diminished by reduced glutathione, ascorbic acid, or bovine serum albumin. Partial protection was afforded by EDTA, suggesting that lipid peroxidation might be involved, but malonaldehyde production was not demonstrable and MnCl2, a potent inhibitor of lipid peroxidation, did not affect the decline in enzyme activities. The decreases in the rates of BP and BZ metabolism were prevented by including NADPH or NADP+ in the preincubation medium. The preincubation conditions causing losses of adrenal enzyme activities did not affect cytochrome P-450 concentrations or substrate binding to cytochromes P-450, as indicated by type I difference spectra. NADH-cytochrome c reductase activity also was not affected, but there were decreases in NADPH-cytochrome c reductase activity that were proportionately similar to the declines in drug-metabolizing activities. Direct assessment of NADPH-cytochrome P-450 reductase revealed similarly large decreases in enzyme activity resulting from preincubation of adrenal microsomes. The results demonstrate a need for extra caution when doing preincubation experiments with adrenal microsomal preparations, and suggest that the thermal lability of adrenal monooxygenases is attributable to effects at the active site of NADPH-cytochrome P-450 reductase. 相似文献
10.