全文获取类型
收费全文 | 1851篇 |
免费 | 273篇 |
国内免费 | 33篇 |
专业分类
耳鼻咽喉 | 29篇 |
儿科学 | 80篇 |
妇产科学 | 30篇 |
基础医学 | 416篇 |
口腔科学 | 22篇 |
临床医学 | 224篇 |
内科学 | 389篇 |
皮肤病学 | 21篇 |
神经病学 | 123篇 |
特种医学 | 111篇 |
外科学 | 159篇 |
综合类 | 43篇 |
一般理论 | 1篇 |
预防医学 | 195篇 |
眼科学 | 32篇 |
药学 | 180篇 |
1篇 | |
中国医学 | 4篇 |
肿瘤学 | 97篇 |
出版年
2022年 | 11篇 |
2021年 | 27篇 |
2019年 | 21篇 |
2018年 | 22篇 |
2017年 | 15篇 |
2016年 | 27篇 |
2015年 | 41篇 |
2014年 | 44篇 |
2013年 | 60篇 |
2012年 | 85篇 |
2011年 | 77篇 |
2010年 | 49篇 |
2009年 | 55篇 |
2008年 | 73篇 |
2007年 | 117篇 |
2006年 | 83篇 |
2005年 | 89篇 |
2004年 | 78篇 |
2003年 | 85篇 |
2002年 | 80篇 |
2001年 | 57篇 |
2000年 | 55篇 |
1999年 | 53篇 |
1998年 | 46篇 |
1997年 | 47篇 |
1996年 | 42篇 |
1995年 | 34篇 |
1994年 | 38篇 |
1993年 | 34篇 |
1992年 | 50篇 |
1991年 | 45篇 |
1990年 | 27篇 |
1989年 | 32篇 |
1988年 | 46篇 |
1987年 | 27篇 |
1986年 | 44篇 |
1985年 | 28篇 |
1984年 | 25篇 |
1983年 | 23篇 |
1982年 | 16篇 |
1980年 | 13篇 |
1979年 | 24篇 |
1978年 | 24篇 |
1976年 | 12篇 |
1975年 | 11篇 |
1974年 | 20篇 |
1973年 | 27篇 |
1972年 | 12篇 |
1971年 | 9篇 |
1970年 | 10篇 |
排序方式: 共有2157条查询结果,搜索用时 15 毫秒
1.
2.
C M Mond D B Walters R S Stricoff E M Prescott A T Prokopetz 《American Industrial Hygiene Association journal》1987,48(10):823-829
A human factors engineering analysis of a chemical containment laboratory was performed to develop appropriate standards for future laboratory design. In order to perform this evaluation, a state-of-the-art facility was studied in depth. Measurements and observations were made of key operating areas. In addition, technicians were observed and interviewed as they performed various tasks. Compiled data were compared to existing ergonomic standards. The occupational implications of instituting ergonomically developed laboratory design standards are as follows: increased worker health, safety and productivity, improved work quality and reduced stress. 相似文献
3.
David G Hicks Brian J Yoder Sarah Short Shannon Tarr Nichole Prescott Joseph P Crowe Andrea E Dawson G Thomas Budd Steven Sizemore Muzaffer Cicek Toni K Choueiri Raymond R Tubbs Daniel Gaile Norma Nowak Mary Ann Accavitti-Loper Andra R Frost Danny R Welch Graham Casey 《Clinical cancer research》2006,12(22):6702-6708
PURPOSE: This study aims to determine the effect of loss of breast cancer metastasis suppressor 1 (BRMS1) protein expression on disease-free survival in breast cancer patients stratified by estrogen receptor (ER), progesterone receptor (PR), or HER2 status, and to determine whether loss of BRMS1 protein expression correlated with genomic copy number changes. EXPERIMENTAL DESIGN: A tissue microarray immunohistochemical analysis was done on tumors of 238 newly diagnosed breast cancer patients who underwent surgery at the Cleveland Clinic between January 1, 1995 and December 31, 1996, and a comparison was made with 5-year clinical follow-up data. Genomic copy number changes were determined by array-based comparative genomic hybridization in 47 breast cancer cases from this population and compared with BRMS1 staining. RESULTS: BRMS1 protein expression was lost in nearly 25% of cases. Patients with tumors that were PR negative (P=0.006) or HER2 positive (P=0.039) and <50 years old at diagnosis (P=0.02) were more likely to be BRMS1 negative. No overall correlation between BRMS1 staining and disease-free survival was observed. A significant correlation, however, was seen between loss of BRMS1 protein expression and reduced disease-free survival when stratified by either loss of ER (P=0.008) or PR (P=0.029) or HER2 overexpression (P=0.026). Overall, there was poor correlation between BRMS1 protein staining and copy number status. CONCLUSIONS: These data suggest a mechanistic relationship between BRMS1 expression, hormone receptor status, and HER2 growth factor. BRMS1 staining could potentially be used in patient stratification in conjunction with other prognostic markers. Further, mechanisms other than genomic deletion account for loss of BRMS1 gene expression in breast tumors. 相似文献
4.
S Prescott M A Hadi R A Elton A W Ritchie G C Foubister J C Gould T B Hargreave 《British journal of urology》1990,66(5):509-514
Two different regimens of cephalosporin antibiotic prophylaxis were compared with antiseptic lubricating jelly to try to prevent infection and complications in 196 men after prostatic surgery. Pre-operative urine was cultured and prostatic chips (170 cases) were also cultured to define the source of any infection. The use of antibiotics was associated with a reduced risk of postoperative bacteriuria. No serious complications occurred, although 1 patient in the antiseptic treated group developed rigors; 79 of 170 patients (46%) had positive prostatic chip cultures, of whom 74 had sterile pre-operative urine. There was no association between the result of chip culture and the presence of a pre-operative catheter. Culture positive patients had an increased risk of post-operative urine infection, although the same organism was found in the prostate and urine in only 36% of cases of post-operative bacteriuria and in 43 (54%) the organism cultured from the prostate was Staphylococcus albus. This study provides further evidence of the benefit of true prophylactic antibiotic therapy for transurethral prostatic surgery and the prostatic chip data suggest that some of the risk is due to pre-operative contamination of the prostate in the absence of per-operative urinary infection or catheterisation. 相似文献
5.
P G Mattison R C Aitken R J Prescott 《Archives of physical medicine and rehabilitation》1992,73(10):926-929
The Edinburgh Rehabilitation Status Scale (ERSS) was applied to 129 attenders at a day center for physical disability. All of the attenders had significant neurological impairment dating from birth or from infancy. Fifty-nine of the subjects (46%) had been diagnosed on conventional grounds as having mental handicap as well as physical disability. ERSS scores were compared with Barthel Index scores in all subjects and with PULSES profile in 50 subjects (27 physical disability alone, 23 combined with mental handicap). The ERSS scores clearly demonstrated significant differences in the level of disablement between the two groups in all four subscales as well as in total scores; the Barthel scores showed differences in self-care and total scores, and, to a lesser extent, in mobility. PULSES failed to differentiate the groups except in one of its subscales. The ERSS is a sensitive index of overall function and is useful in highlighting the additive effect of mental handicap and physical disability, a difference which may not be apparent when other assessment scales are used. 相似文献
6.
7.
British Thoracic Society study of cryptogenic fibrosing alveolitis: current presentation and initial management. Fibrosing Alveolitis Subcommittee of the Research Committee of the British Thoracic Society 总被引:9,自引:3,他引:6
下载免费PDF全文
![点击此处可从《Thorax》网站下载免费的PDF全文](/ch/ext_images/free.gif)
BACKGROUND: Mortality due to cryptogenic fibrosing alveolitis (CFA) is increasing, particularly in the elderly. Optimum management remains uncertain and previous studies of the disease have largely been from specialist centres. A national study was carried out of the presentation and initial management of CFA in the UK. METHODS: All respiratory physicians in England, Scotland and Wales were invited to enter patients with newly diagnosed CFA over a two year period. CFA was diagnosed on histological grounds or according to clinical criteria which included the absence of a defined connective tissue disorder or pneumoconiosis. Participating physicians (n = 150) completed a questionnaire at patient entry and at all subsequent follow up visits and death. RESULTS: A total of 588 patients (373 men, 63%) were studied of whom 441 (75%) were referrals from primary care. Their mean (SD) age was 67.4 (10.0) years and median duration of symptoms at presentation was 9.0 months. Clubbing was more common in men (203/373; 54%) than in women (86/ 215; 40%); 209 patients (36%) were graded as severely breathless at presentation. A history of dust exposure (organic or inorganic) was present in 274 patients (47%) of whom 87 had had some exposure to asbestos. Subjects exposed to dust were more likely to have smoked and had slightly higher mean lung volumes, but were otherwise indistinguishable from those not exposed in terms of clinical presentation, management, and outcome. Transbronchial biopsy specimens were taken in 164 patients (28%) and open lung biopsy specimens in 73 (12%), but 60% had no histological diagnostic procedure. Biopsy procedures were more likely to be performed in younger patients, those with better lung function, and those with a history of asbestos exposure. At presentation a decision not to initiate specific treatment was made in 284 cases (48%). The decision to initiate treatment was made predominantly on symptomatic grounds. Two years after the close of entry to the study 266 patients (45%) had died. CONCLUSIONS: CFA is predominantly a disease of elderly patients and has a poor prognosis. Physicians generally considered CFA to be a clinical diagnosis and did not initiate treatment in up to half of patients at presentation.
相似文献
相似文献
8.
9.
S D Qiu C Y Young D L Bilhartz J L Prescott G M Farrow W W He D J Tindall 《The Journal of urology》1990,144(6):1550-1556
Prostate-specific antigen (PSA) mRNA was detected by in situ hybridization utilizing a 428 base pair [35S]-labelled cDNA probe from the 3' noncoding region of the PSA gene. Thirty six fresh surgical specimens were collected from patients undergoing radical retropubic prostatectomy for carcinoma of the prostate. Quantitative analysis of the levels of PSA mRNA in both the benign and malignant tissues was performed using an IBAS 2000 Image Analysis System. The results of this study demonstrated that there is a significant decrease in the expression of PSA mRNA in the carcinoma tissue when compared to the benign epithelium. The average binding (number of silver grains/1 x 10(4) microns. 2) for 20 specimens of malignant epithelium was 475 +/- 161 and 586 +/- 140 for 16 specimens of benign epithelium (p less than 0.05). Eleven patients had both benign and malignant tissue from the same surgical specimen available for study. From these paired specimens, the PSA mRNA expression was also significantly reduced in the malignant epithelium when compared to the benign epithelium, 445 +/- 162 and 588 +/- 135 respectively (p less than 0.005). The PSA protein was detected using a monoclonal antibody to PSA with an immunohistochemical staining technique. The PSA protein expression paralleled the expression of the PSA mRNA in the majority of the tissue sections. Many of the tumor specimens showed a heterogeneous expression of PSA, whereas all of the benign epithelium had a uniform high level of PSA expression. In conclusion, PSA mRNA and protein are located only within the glandular epithelial tissue, the expression of PSA protein parallels that of the PSA mRNA, and both the PSA protein and PSA mRNA are significantly decreased in the malignant epithelium when compared to benign prostatic epithelium. 相似文献
10.
J. A. Dunstan J. Roper L. Mitoulas† P. E. Hartmann† K. Simmer S. L. Prescott 《Clinical and experimental allergy》2004,34(8):1237-1242
BACKGROUND: Breast milk contains many immunomodulatory factors (soluble CD14 (sCD14), IgA and cytokines) with the potential to influence infant immune development. OBJECTIVE: To determine if changes in breast milk omega-3 polyunsaturated fatty acid (n-3 PUFA) composition as a result of maternal dietary fish oil supplementation during pregnancy can modify levels of these immunological parameters in breast milk. METHOD: In a randomized controlled trial, 83 atopic women received either 4 g fish oil capsules (containing 3.7 g n-3 PUFA) (n = 40) or 4 g olive oil capsules (n = 43) from 20 weeks gestation until delivery. Breast milk was collected 3 days post-partum and fatty acids were analysed by gas liquid chromatography and IgA, sCD14 and cytokines (IL-5, IL-6, IL-10, TNF-alpha and IFN-gamma) were quantitated by ELISA or time resolved fluorescence (TRF). RESULTS: Omega-3 docosahexaenoic acid (DHA; 22:6n-3) and eicosapentaenoic acid (EPA; 20:5n-3) levels were significantly higher (P < 0.001) in breast milk from women supplemented with fish oil (n = 33, DHA mean 1.15%, SD 0.47% and EPA mean 0.16%, SD 0.07%) than in samples from the control group (n = 40, DHA mean 0.50%, SD 0.17% and EPA mean 0.05%, SD 0.02%). Breast milk arachidonic acid (AA; 20:4n-6) levels were significantly lower (P = 0.045) in the fish oil group (mean 0.55%, SD 0.12%) compared with the control group (mean 0.61%, SD 0.14%). Breast milk IgA was positively correlated with DHA (P = 0.046) and 22:5n-3 (P = 0.003), but inversely correlated with linoleic acid (LA; 18:2n-6) (P=0.034). Levels of sCD14 were also positively correlated with 22:5n-3 (P=0.009). Cytokines involved in IgA synthesis (IL-10 and IL-6) were also significantly correlated with both IgA and n-3 PUFA levels, although there were no differences in the levels of breast milk IgA, sCD14 or cytokines between study groups. CONCLUSION: Supplementation with fish oil during pregnancy significantly alters early post-partum breast milk fatty acid composition. omega-3 PUFA levels were positively associated with IgA and sCD14 levels, suggesting a relationship between fatty acid status and mucosal immune function. 相似文献