全文获取类型
收费全文 | 31695篇 |
免费 | 2976篇 |
国内免费 | 43篇 |
专业分类
耳鼻咽喉 | 286篇 |
儿科学 | 1134篇 |
妇产科学 | 1061篇 |
基础医学 | 4255篇 |
口腔科学 | 489篇 |
临床医学 | 4140篇 |
内科学 | 5355篇 |
皮肤病学 | 425篇 |
神经病学 | 3341篇 |
特种医学 | 1099篇 |
外科学 | 3562篇 |
综合类 | 585篇 |
一般理论 | 48篇 |
预防医学 | 3993篇 |
眼科学 | 497篇 |
药学 | 2279篇 |
中国医学 | 27篇 |
肿瘤学 | 2138篇 |
出版年
2023年 | 190篇 |
2022年 | 330篇 |
2021年 | 716篇 |
2020年 | 481篇 |
2019年 | 720篇 |
2018年 | 839篇 |
2017年 | 647篇 |
2016年 | 678篇 |
2015年 | 742篇 |
2014年 | 1012篇 |
2013年 | 1388篇 |
2012年 | 2025篇 |
2011年 | 2122篇 |
2010年 | 1151篇 |
2009年 | 985篇 |
2008年 | 1724篇 |
2007年 | 1749篇 |
2006年 | 1729篇 |
2005年 | 1702篇 |
2004年 | 1362篇 |
2003年 | 1311篇 |
2002年 | 1180篇 |
2001年 | 640篇 |
2000年 | 638篇 |
1999年 | 578篇 |
1998年 | 311篇 |
1997年 | 254篇 |
1996年 | 208篇 |
1995年 | 200篇 |
1994年 | 187篇 |
1993年 | 167篇 |
1992年 | 416篇 |
1991年 | 431篇 |
1990年 | 436篇 |
1989年 | 392篇 |
1988年 | 406篇 |
1987年 | 414篇 |
1986年 | 333篇 |
1985年 | 361篇 |
1984年 | 281篇 |
1983年 | 232篇 |
1982年 | 153篇 |
1979年 | 263篇 |
1978年 | 205篇 |
1976年 | 173篇 |
1974年 | 186篇 |
1973年 | 176篇 |
1972年 | 163篇 |
1971年 | 149篇 |
1969年 | 176篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
91.
92.
Laura K Brennan Elizabeth A Baker Debra Haire-Joshu Ross C Brownson 《Health education & behavior》2003,30(6):740-755
Although the relationship of psychosocial factors to physical activity has been explored, there is increased interest in how perceptions of the community environment influence behavior. However, few methodological studies have incorporated perceptions of the social and community environment (protective social factors) or addressed key measurement issues. Computer-assisted telephone interviews were administered to a national sample of 1,818 U.S. adults. Unadjusted and multivariate-adjusted odds ratios were calculated to compare active and inactive participants by Protective Social Factors (PSF) scores and selected sociodemographics. Confirmatory factor analysis and reliability analysis suggested strong PSF scale psychometric properties (alpha = .92). After adjustment for potential confounders, a 10-point rise in the PSF score resulted in a 12% increased likelihood of meeting Centers for Disease Control and Prevention/American College of Sports Medicine recommendations. Additional analyses indicated that greater perceived PSFs were associated with meeting these recommendations among Whites but not among African Americans. 相似文献
93.
Use of Sentinel blood culture system for analysis of specimens from potentially infected prosthetic joints. 下载免费PDF全文
The Sentinel blood culture system was used for the analysis of 657 specimens from infected prosthetic joints and blood cultures (83 from prosthetic joints and 574 from standard blood cultures). The positivity rate was similar for specimens from prosthetic joints and blood cultures (18% compared with 14%). However, there was an unacceptable rate of false positive results with specimens from prosthetic joints (58% compared with 8%). This high false positivity rate was due to (i) prolonged incubation and (ii) the lack of blood in these specimens. It is therefore recommended that the Sentinel system should only be used for the initial seven days of incubation of specimens taken from prosthetic joints. Further incubation should take place in a standard incubator and a terminal subculture performed after 21 days. 相似文献
94.
Patricia J Martens Randall Fransoo Elaine Burland Charles Burchill Heather J Prior Okechukwu Ekuma 《Revue canadienne de psychiatrie》2007,52(9):581-590
OBJECTIVES: To determine the prevalence of mental illness in older adults and its effect on home care and personal care home (PCH) use. METHODS: Using nonidentifying administrative records (fiscal years 1997-1998 to 2001-2002) from the Population Health Research Data Repository housed at the Manitoba Centre for Health Policy, we determined the 5-year period prevalence for individuals aged 55 years and over (119 539 men and 145 752 women) for 3 mental illness categories: cumulative mental disorders (those having a diagnosis of depression, anxiety disorder, personality disorder, schizophrenia, and [or] substance abuse), any mental illness, and dementia. We calculated age-specific and age-adjusted rates of home care and PCH use and the prevalence of mental illness in PCH residents. RESULTS: From the group aged 55 to 59 years to the group aged 90 years or older, the prevalence of mental illness increased with the population's age. The prevalence of any mental illness rose from 32.4% to 45.0% in men and from 42.6% to 51.9% in women, and dementia prevalence rose from 2.0% to 33.6% in men and from 1.3% to 40.3% in women. The age-adjusted annual rates of open home care cases per 1000 population aged 55 and older varied by mental illness grouping (no mental disorder, 57 for men and 91 for women; cumulative mental disorders, 162 for men and 191 for women; dementia, 300 for men and 338 for women). The age-adjusted rates of PCH use per 1000 population aged 75 years and older also varied by mental illness grouping (no mental disorder, 53 for men and 78 for women; cumulative mental disorders, 305 for men and 373 for women; dementia, 542 for men and 669 for women). Among patients admitted to (or resident in) a PCH in 2002-2003, 74.6% (87.1%) had a mental illness, and 46.0% (69.0%) had dementia. CONCLUSIONS: Mental illness affects the use of home care and nursing homes profoundly. Individuals with dementia used home care at 3 times the rate of those having no mental illness diagnosis, and they used PCHs at 8 times the rate. 相似文献
95.
Amplitude and time course of spontaneous gamma-aminobutyric acid (GABA)-mediated miniature postsynaptic currents (MPSCs), recorded in cultured embryonic hippocampal neurons in presence of either tetrodotoxin (TTX) or increased external [Mg2+/Ca2+] ratio, revealed that they form two classes. The distribution of the most commonly recorded MPSCs was skewed both in terms of peak amplitude and rise-time (skew-MPSCs, mode: 70-120 pS). Another, less frequent class (mode: 1-3 nS) formed bell-shaped (bell-MPSCs) amplitude and rise-time distributions. MPSC initial slope did not correlate with rise time, indicating that smaller MPSCs were not electrotonically attenuated. Bell-MPSCs did not result from the integration of skew-MPSCs and both classes appeared to be composed of subunits. 相似文献
96.
Heather A Mitchell Todd H Ahern L Cameron Liles Martin A Javors David Weinshenker 《Neuropsychopharmacology》2006,60(10):1046-1052
BACKGROUND: Acute administration of different classes of antidepressants can enhance or reduce spontaneous locomotor activity in a novel environment, but the effects of chronic antidepressant treatment on spontaneous locomotor activity in novel and familiar environments are less well characterized. Because norepinephrine is an important regulator of spontaneous locomotor activity, we speculated that norepinephrine transporter blockade contributes to the effects of some antidepressants on spontaneous locomotor activity. METHODS: Antidepressant drugs (reboxetine, desipramine, imipramine, venlafaxine, bupropion) were administered acutely (intraperitoneal) or chronically (via osmotic minipump) to control and norepinephrine transporter knockout mice, and spontaneous locomotor activity in novel or familiar environments was recorded. RESULTS: Acute treatment with most norepinephrine transporter-blocking antidepressants decreased spontaneous locomotor activity in a novel environment, whereas chronic treatment decreased spontaneous locomotor activity in both novel and familiar environments. The exception was bupropion, a dual norepinephrine transporter/dopamine transporter blocker, which tended to increase spontaneous locomotor activity. Coadministration of reboxetine and the dopamine transporter blocker GBR 12909 also increased spontaneous locomotor activity. Norepinephrine transporter knockout mice had low basal spontaneous locomotor activity, which was increased by bupropion, whereas reboxetine had no effect in norepinephrine transporter knockout mice. CONCLUSIONS: Acute or chronic inactivation of the norepinephrine transporter decreases spontaneous locomotor activity in novel and familiar environments unless coupled with dopamine transporter blockade. 相似文献
97.
Gordon Winocur Fergus I M Craik Brian Levine Ian H Robertson Malcolm A Binns Michael Alexander Sandra Black Deirdre Dawson Heather Palmer Tara McHugh Donald T Stuss 《Journal of the International Neuropsychological Society》2007,13(1):166-171
This study provides an overview of the papers emanating from the experimental trial that evaluated a new cognitive rehabilitation program in older adults who were experiencing normal cognitive decline. The main features of the design are summarized, along with evidence that the training produced long-lasting improvement in memory performance, goal management, and psychosocial status. The benefits were attributed to several factors, including the program's emphasis on techniques that promoted efficient strategic processing. Limitations of the program and directions for future research are discussed. 相似文献
98.
S R Baker A A Forastiere R Wheeler B R Medvec 《Archives of otolaryngology--head & neck surgery》1987,113(11):1183-1190
Intra-arterial chemotherapy for the treatment of localized malignant neoplasms in the head and neck is an appealing approach for several reasons. Perhaps the most important is the possibility of obtaining a regional advantage such that an increased drug concentration is delivered systemically. The patient may, therefore, be spared systemic toxicity. We report our accumulated experience using a totally implantable infusion pump in 37 patients. A total of 42 pumps were implanted: 28 single-catheter pumps and 14 dual-catheter pumps. Radionuclide imaging demonstrated total perfusion of the tumor in all patients. A combination of cisplatin (50 to 100 mg/m2) and floxuridine (0.01 to 0.045 mg/kg/d) was used to treat 26 patients. For these heavily pretreated patients, we observed a 43% complete and partial response rate in the subgroup of patients with squamous cell carcinoma. These results are comparable with those reported for these drugs administered systemically and for other drug combinations tested in the treatment of recurrence disease. 相似文献
99.
Haemodynamic assessment of the femoropopliteal segment: comparison of pressure and Doppler methods using ROC curve analysis 总被引:1,自引:0,他引:1
Combined aorto-iliac and femoropopliteal vascular disease remains a problem in vascular surgery. Arteriography does not provide information on the relative contributions of the two lesions to the presenting symptoms. Aorto-iliac haemodynamics may reveal occult aorto-iliac disease but does not show whether combined proximal and distal reconstruction will be required to provide symptomatic relief. Haemodynamic assessment of both segments may help in this respect. A haemodynamic assessment of the femoropopliteal segment of 72 limbs in 38 patients is reported. The segmental pressure drop between a common femoral arterial cannula and a below-knee occlusion cuff is compared with a non-invasive Doppler method combining both transit time and damping factor. Comparison is made using receiver operating characteristic (ROC) curve analysis. The measurement of segmental pressure drop is more accurate than the Doppler method in detection of femoropopliteal stenoses of greater than 50 per cent of the luminal diameter (P less than 0.05). 相似文献
100.
Effect of meal on the physiological and physicochemical actions of potassium citrate 总被引:1,自引:0,他引:1
The effect of meals on the physiological and physicochemical actions of potassium citrate was examined in 8 patients with nephrolithiasis maintained on a constant metabolic dietary regimen. Potassium citrate (20 mEq. 3 times per day), whether given with food or on an empty stomach, significantly increased urinary pH, citrate and potassium, and decreased urinary calcium and ammonium. Moreover, potassium citrate decreased urinary saturation of calcium oxalate and uric acid, although it slightly increased that of brushite. However, there was no significant difference in these measures when the drug was given with meals from the time when it was given on an empty stomach. Thus, the effect of potassium citrate on urinary risk factors is unaffected by food. 相似文献