全文获取类型
收费全文 | 9230篇 |
免费 | 708篇 |
国内免费 | 18篇 |
专业分类
耳鼻咽喉 | 86篇 |
儿科学 | 414篇 |
妇产科学 | 228篇 |
基础医学 | 1186篇 |
口腔科学 | 246篇 |
临床医学 | 1174篇 |
内科学 | 1575篇 |
皮肤病学 | 111篇 |
神经病学 | 929篇 |
特种医学 | 213篇 |
外国民族医学 | 3篇 |
外科学 | 1038篇 |
综合类 | 107篇 |
一般理论 | 13篇 |
预防医学 | 1300篇 |
眼科学 | 120篇 |
药学 | 579篇 |
中国医学 | 22篇 |
肿瘤学 | 612篇 |
出版年
2023年 | 84篇 |
2022年 | 135篇 |
2021年 | 305篇 |
2020年 | 169篇 |
2019年 | 292篇 |
2018年 | 273篇 |
2017年 | 228篇 |
2016年 | 210篇 |
2015年 | 230篇 |
2014年 | 332篇 |
2013年 | 470篇 |
2012年 | 670篇 |
2011年 | 660篇 |
2010年 | 287篇 |
2009年 | 304篇 |
2008年 | 514篇 |
2007年 | 543篇 |
2006年 | 537篇 |
2005年 | 526篇 |
2004年 | 444篇 |
2003年 | 385篇 |
2002年 | 314篇 |
2001年 | 164篇 |
2000年 | 160篇 |
1999年 | 136篇 |
1998年 | 70篇 |
1997年 | 49篇 |
1996年 | 31篇 |
1995年 | 41篇 |
1992年 | 116篇 |
1991年 | 73篇 |
1990年 | 81篇 |
1989年 | 77篇 |
1988年 | 60篇 |
1987年 | 69篇 |
1986年 | 68篇 |
1985年 | 63篇 |
1984年 | 45篇 |
1983年 | 40篇 |
1982年 | 28篇 |
1980年 | 36篇 |
1979年 | 53篇 |
1978年 | 42篇 |
1977年 | 48篇 |
1976年 | 34篇 |
1975年 | 33篇 |
1974年 | 37篇 |
1973年 | 43篇 |
1972年 | 41篇 |
1970年 | 47篇 |
排序方式: 共有9956条查询结果,搜索用时 15 毫秒
11.
C Casanova C G Cote J M Marin J P de Torres A Aguirre-Jaime R Mendez L Dordelly B R Celli 《The European respiratory journal》2007,29(3):535-540
The 6-min walking distance (6MWD) test is used in clinical practice and research into patients with chronic obstructive pulmonary disease (COPD). However, little is known about natural long-term change in this parameter. The 6MWD was measured at baseline and then annually for 5 yrs in 294 patients with COPD and its annual rate of decline was determined. Forced expiratory volume in one second (FEV1) was also measured and the relationship between changes in both markers was explored. At baseline, the median 6MWD was 380 m (range 160-600 m). It declined by 19% (16 m.yr(-1)) over the 5 yrs compared with baseline in patients with American Thoracic Society/European Respiratory Society stage III COPD (FEV1 30-50% predicted) and by 26% (15 m.yr(-1)) in patients with stage IV COPD (FEV1 <30% pred). Over the 5-yr follow-up, the proportion of patients with a minimal clinically significant decline of 54 m increased with the severity of the disease. It was 24% in stage II, 45% in stage III, and 63% in stage IV disease. In contrast, the rate of decline of FEV1 was greater in patients with milder airflow obstruction and lesser in patients with lower absolute FEV1 values. In conclusion, the 6-min walking distance test provides increasingly useful information as the severity of chronic obstructive pulmonary disease increases. 相似文献
12.
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
13.
Prospective study of antigenemia,plasma viremia and lymphocytic viremia in HIV-infected hemophiliacs
S. Melón Garcia M. de Oña Navarro C. Rodriguez Pinto M. Fernández Urgellés A. Martinez Gutierrez P. de la Iglesia F. J. Mendez García 《European journal of clinical microbiology & infectious diseases》1995,14(5):400-405
A total of 186 blood samples from 24 HIV-1 seropositive hemophiliac patients, monitored every four months for 29 months, were investigated for the presence of viral antigen in plasma. In addition, peripheral blood mononuclear cells (PBMC) were cultured for HIV-1, using normal PBMC as a target for replication. Antigenemia was detected in 51 % of the patients and from PBMC in 87.5 % of the patients. The incidence of HIV isolation in asymptomatic patients (42.8 %) was similar to that found in symptomatic patients (51.4 %). Patients with opportunistic infections had a higher incidence of lymphocytic viremia (p<0.05). Plasma viremia was closely associated (p<0.05) with low CD4+ counts and infection progression. The persistence of antigenemia was also a marker of a poor clinical course. In treated patients, plasma viremia was the marker that better correlated with the clinical course, and it did not appear during the first nine months of therapy. Zidovudine doses of >500 mg/day significantly lowered the appearance of antigenemia and lymphocytic viremia (p<0.05). 相似文献
14.
Farming is an occupation that blends the work and home environments and traditionally involves active participation of all family members, including older farmers. The work patterns of older farmers, including typical work hours, range of activities, and health status, are not well documented. This study, surveying a random sample of older Illinois farmers (N=87), focused on these gaps in the literature. Older farmers were found to work long hours in many farm tasks, more than would be expected in other occupational groups. Further, older farmers were found to have several chronic diseases at higher rates than the general population of the same age and gender; mental health implications were also identified. Rural occupational health nurses are in an optimal position to positively impact older farmers' mental and physical health status. 相似文献
15.
Effects of two extracellular matrices on morphologic and biochemical properties of human type II cells in vitro 总被引:1,自引:0,他引:1
Previous observations have suggested that differentiated functions of adult rat type II alveolar cells are affected in part by cell-matrix interactions. We examined several aspects of differentiated adult human type II cells cultured on either bovine corneal endothelial cell extracellular matrix (BCECM) or matrix derived from the Englebreth-Holm-Swarm tumor (EHS). Compared to cells cultured on BCECM, adult human type II cells grown on EHS assumed a more cuboidal shape, had a more defined apical-basal polarity, and appeared to contain a greater number of lamellar bodies and neutral lipid inclusions. These cells also incorporated a greater percentage of [14C]acetate into saturated phosphatidylcholine (SPC) than did their counterparts grown on BCECM. In contrast, the relative incorporation of [14C]acetate into phosphatidylglycerol (PG) was lower in cells grown on EHS than cells cultured on BCECM. The histochemical stain for alkaline phosphatase was useful in identification of human type II cells. Alkaline phosphatase expression was elevated in cells cultured on EHS compared to those cultured on BCECM. These results suggest that maintenance of a differentiated morphology, lipid synthesis, and expression of alkaline phosphatase activity by primary cultures of adult human type II cells are also influenced by cell-matrix interactions. All markers of differentiated function of type II cells except synthesis of PG are better maintained on EHS than on BCECM. Under the conditions of these experiments, synthesis of SPC and PG appears to be independently regulated. 相似文献
16.
L L Williams H W Lowery B T Shannon 《Archives of otolaryngology--head & neck surgery》1987,113(4):397-400
Aspects of humoral and cell-mediated immunity that might characterize the continuation of symptoms in 25 patients with chronic Meniere's disease were examined. We found significant elevations of both humoral and cellular immune responses to viral antigens of herpes simplex I, varicella-zoster, rubella, and cytomegalovirus. Serum immunoglobulins were quantitatively abnormal in 24 of 25 patients, without a consistent pattern. These immune responses may be linked to persistent viral infection in chronic Meniere's disease. 相似文献
17.
Robert C. Eberhart Mark S. Munro Geraldine B. Williams Padmakar V. Kulkarni W. Allen Shannon Jr. † Bruce E. Brink William J. Fry 《Artificial organs》1987,11(5):375-382
The short-term albumin affinity and thrombo-resistance of a polyether polyurethane vascular graft have been improved. The method is based on the C18 alkylation of the polymer. Thrombus formation by a planimetric technique and albumin retention on wire-reinforced polyurethane tubes, both C18 alkylated and untreated, were measured in short-term (4-h) exposure at femoral arterial sites in the dog. 125I-Albumin was preabsorbed on tubes and then exposed to blood for successive 2-h periods. Albumin uptake on alkylated tubes prior to blood exposure and retention following 2 h of blood exposure were significantly greater than on controls. Following a fast desorption phase in blood, the remaining albumin was more slowly desorbed from alkylated than from control tubes. Reincubation with albumin and blood reexposure produced a similar tendency, suggesting blood conditioning does not reduce the albumin affinity-enhancing property of C18 alkylation in the short term. Blood-preconditioning experiments suggested endogenous albumin has a high affinity for the C18-alkylated surface. Scanning electron microscopic examination showed thrombus and platelet densities were higher on control than on alkylated surfaces. These results suggest in vivo albumin affinity is increased for C18-alkylated polyurethane, which may be linked to decreased thrombus formation on these surfaces. 相似文献
18.
J. G. Gross W. R. Freeman M. H. Goldbaum T. L. Mendez 《The British journal of ophthalmology》1989,73(6):435-439
Many vitreoretinal procedures are performed in offices and hospitals where cost control is important. We describe three useful devices and techniques that facilitate these procedures at minimal expense and often greater convenience. These include an accurate method for localising the pars plana without the use of callipers, an inexpensive, reliable, pressure regulated air pump for fluid-air exchange, and an easy method for intraocular injection of silicone oil through 20 gauge instrumentation without the need for expensive pumps. These procedures and techniques should prove to be useful in the treatment of vitreoretinal disease. 相似文献
19.
20.
Katie Kompoliti Yaping Chu Kathleen M Shannon Jeffrey H Kordower 《Movement disorders》2007,22(11):1630-1633
To date, there is no clinicopathological correlation of adrenal medullary transplant cases in patients with survival beyond a few years. Postmortem examination of a brain from a patient with Parkinson's disease (PD), 16 years after autologous adrenal medullary transplant, was performed using tyrosine hydroxylase (TH) and chromogranin A. The patient experienced a four-year initial improvement in motor function followed by resumption of the progressive nature of her disease that continued until her death. She expired 16 years following grafting. At autopsy, TH stain of the brain revealed severe loss of TH-immunoreactivity in the substantia nigra and Lewy bodies, confirming the diagnosis of PD. The transplant site was identified by the presence of scarring and there was complete absence of any TH staining cells at the site of the transplant. There were few surviving cells staining with chromogranin A. The absence of TH-staining cells in the transplant 16 years after surgery provides further evidence that adrenal medullary transplants do not survive in the long term. 相似文献