全文获取类型
收费全文 | 1948篇 |
免费 | 121篇 |
国内免费 | 11篇 |
专业分类
耳鼻咽喉 | 12篇 |
儿科学 | 49篇 |
妇产科学 | 39篇 |
基础医学 | 210篇 |
口腔科学 | 44篇 |
临床医学 | 138篇 |
内科学 | 588篇 |
皮肤病学 | 38篇 |
神经病学 | 148篇 |
特种医学 | 124篇 |
外科学 | 258篇 |
综合类 | 34篇 |
预防医学 | 145篇 |
眼科学 | 57篇 |
药学 | 120篇 |
中国医学 | 3篇 |
肿瘤学 | 73篇 |
出版年
2022年 | 20篇 |
2021年 | 51篇 |
2020年 | 22篇 |
2019年 | 39篇 |
2018年 | 53篇 |
2017年 | 28篇 |
2016年 | 41篇 |
2015年 | 42篇 |
2014年 | 52篇 |
2013年 | 73篇 |
2012年 | 103篇 |
2011年 | 76篇 |
2010年 | 79篇 |
2009年 | 53篇 |
2008年 | 67篇 |
2007年 | 81篇 |
2006年 | 89篇 |
2005年 | 87篇 |
2004年 | 80篇 |
2003年 | 90篇 |
2002年 | 77篇 |
2001年 | 58篇 |
2000年 | 67篇 |
1999年 | 78篇 |
1998年 | 48篇 |
1997年 | 35篇 |
1996年 | 31篇 |
1995年 | 25篇 |
1994年 | 33篇 |
1993年 | 29篇 |
1992年 | 30篇 |
1991年 | 28篇 |
1990年 | 21篇 |
1989年 | 30篇 |
1988年 | 37篇 |
1987年 | 22篇 |
1986年 | 29篇 |
1985年 | 21篇 |
1984年 | 21篇 |
1983年 | 13篇 |
1982年 | 12篇 |
1981年 | 16篇 |
1980年 | 15篇 |
1979年 | 6篇 |
1978年 | 6篇 |
1977年 | 14篇 |
1976年 | 14篇 |
1975年 | 10篇 |
1974年 | 5篇 |
1970年 | 5篇 |
排序方式: 共有2080条查询结果,搜索用时 11 毫秒
21.
Although musculoskeletal disorders of the low back and upper extremities can affect military readiness, little is known about their extent and risk factors in the U.S. Marine Corps. Using the Defense Medical Epidemiology and Defense Medical Surveillance System databases, back and upper extremity diagnostic categories were among the top four sources of outpatient visits and duty limitation among enlisted Marines. Back disorders were also found to be the fifth most common cause for lost time. Subsequently, high-risk occupations were identified, age-related trends for clinic visit rates were determined, and rate ratios were computed for the top 15 low back and upper extremity diagnoses among enlisted Marines from 1997 through 1998. Occupational categories with the highest rates of musculoskeletal-related outpatient visits included image interpretation, auditing and accounting, disturbsing, surveillance/target acquisition, and aircraft launch equipment. Significantly increasing linear trends in rates across age groups were found for most diagnoses. For 1998, age-specific rate ratios indicated significantly higher rates for most low back and upper extremity disorders for females; lower rank (i.e., E1-E4) was also a risk, but for fewer diagnoses. The findings emphasize the need to identify modifiable (e.g., work-related, individual) risk factors and to develop focused primary and secondary prevention programs for musculoskeletal disorders in the Marine Corps. Subsequently, these efforts can assist in reducing associated effects, maximizing resource utilization, and enhancing operational readiness. 相似文献
22.
23.
BARI NUHOLU ALI AYYILDIZ VECIHI FIDAN ÖZDEN CEBECI UUR KOAR CANKON GERMIYANOLU 《International journal of urology》2006,13(2):109-110
OBJECTIVE: Nocturnal enuresis is a common pediatric problem, the etiology of which is unclear. In recent years, various studies have been published stating that children with nocturnal enuresis exhibit growth and skeletal maturation retardation. METHODS: In this cross-sectional study, we included 27 patients (16 boys, 11 girls) between the ages of 6 and 14 years who had presented with primary nocturnal enuresis (PNE) complaints. We included in the evaluation 19 healthy subjects (12 boys, 7 girls), who were the siblings of the children with PNE, as the control group. RESULTS: The patients in both groups were similar in chronological age, bone age, height and weight, with no significant difference between groups (P>0.05). CONCLUSION: The two groups in our study consisted of the same genetic background. Thus, our results were found to be different from the previous studies. We have concluded that there is no direct relationship between enuresis nocturnal and skeletal maturation. 相似文献
24.
25.
Tugues S Morales-Ruiz M Fernandez-Varo G Ros J Arteta D Muñoz-Luque J Arroyo V Rodés J Jiménez W 《Gastroenterology》2005,129(5):1686-1695
BACKGROUND & AIMS: There is a long-standing interest in the identification of endothelial-specific pathways for therapeutic targeting in cirrhosis. Therefore, the aim of this study was to evaluate differences in gene expression patterns between liver endothelial cells (LECs) from control and cirrhotic rats by using microarrays. METHODS: LECs were obtained by isopycnic centrifugation. LECs gene expression was then analyzed on high-density oligonucleotide microarrays. RESULTS: Analysis of gene expression revealed that most of the differentially expressed mRNA in cirrhosis are associated with extracellular matrix remodeling, inflammation, antioxidant/stress response, and cell signaling. CONCLUSIONS: The collective expression changes observed within some functional groups of genes indicate that LECs in cirrhotic livers may contribute to lymphangiogenesis, enhancement of fibrogenesis and inflammatory processes, changes in cell-cell interaction with up-regulation of adherens junction proteins, and alterations in the intrahepatic vascular tone because of the down-regulation of genes involved in vasodilatation. 相似文献
26.
Shimada Y; Migliaccio G; Ralph H; Migliaccio AR; Shaw H$corrected to Ralph H 《Blood》1993,81(4):935-941
Recently, a variety of growth factor-dependent subclones of the murine interleukin-3 (IL-3)-dependent cell line 32D have been isolated. These subclones include those dependent for growth on erythropoietin (Epo) (32D Epo), granulocyte-macrophage colony-stimulating factor (GM-CSF) (32D GM), or granulocyte colony-stimulating factor (G-CSF) (32D G). 32D Epo1.1 is a revertant of 32D Epo and is capable of growing in IL-3. These cell lines express the differentiation program appropriate to the specific growth factor and depend on the growth factors not only for proliferation but also for survival. To determine how the signal for proliferation is triggered by various growth factors, we examined the DNA histograms and the expression of cell cycle-specific genes in the different cell lines. The cell cycle-specific genes analyzed were myc (early G1), myb (late G1), and the structural genes for the calcium- binding protein 2A9 (middle G1) and histone H3 (G1-S boundary). The DNA histogram analysis of cells in the logarithmic phase of growth showed that approximately 40% of 32D, 32D GM, 32D G, and 32D Epo1.1 (growing in IL-3) were cells with a 2N DNA content (and therefore in G0/G1), and another 40% have a DNA content intermediate between 2N and 4N (in S phase). In contrast, 32D Epo and 32D Epo1.1 (growing in Epo) had fewer cells in the G0/G1 phase of the cell cycle compared with the number of cells that were in the S phase (19% to 31% v 69% to 78%, respectively). Because all the cell lines have comparable doubling times (15 to 18 hours), the cell distribution among the phases of the cell cycle is proportional to the length of the phase. Therefore, cells growing in IL- 3 (32D and 32D Epo1.1), GM-CSF (32D GM), or G-CSF (32D G) progress along the cycle in a manner typical of previously reported nontransformed cell lines. In contrast, cells growing in Epo (32D Epo or 32D Epo1.1) spend relatively less time in G0/G1 and correspondingly more time in S. These data were confirmed by the analysis of the tritiated thymidine (3H-TdR) suicide rate and of the expression of cell cycle-specific genes. The 32D and 32D Epo1.1 cells growing in IL-3 had a suicide rate of congruent to 50%, whereas the suicide rate of 32D Epo and 32D Epo1.1 growing in Epo was higher than 75%.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
27.
Recurrence of spontaneous bacterial peritonitis in cirrhosis: frequency and predictive factors 总被引:6,自引:0,他引:6
We investigated whether spontaneous bacterial peritonitis in cirrhosis is a recurrent process and attempted to identify possible predictors of recurrence in 75 consecutive cirrhotics who had recovered from a first episode of spontaneous bacterial peritonitis between January, 1981 and December, 1984 and who were followed closely throughout their illness (follow-up period 10 +/- 13 months; mean +/- S.D.). Thirty-eight patients (51%) developed one or more episodes of spontaneous bacterial peritonitis during follow-up, the probability of recurrence (Kaplan-Meier's method) being 43% at 6 months, 69% at 1 year and 74% at 2 years. Twenty-three variables (age, sex, etiology of cirrhosis, standard liver and renal function tests and characteristics of the first spontaneous bacterial peritonitis) were analyzed as possible predictors of recurrence of spontaneous bacterial peritonitis. In univariate analysis (curves of Kaplan-Meier compared with Mantel-Cox's method), serum bilirubin greater than 4 mg per dl, prothrombin less than or equal to 45% and protein concentration in ascitic fluid less than or equal to 1 gm per dl were significantly (p less than 0.05) associated with a high risk or recurrence of spontaneous bacterial peritonitis. In multivariate analysis (Cox multiple regression model), only ascitic fluid protein concentration (p = 0.005) and prothrombin activity (p = 0.009) were found to be independent predictors of recurrence of spontaneous bacterial peritonitis. Fifty-nine patients (79%) died during follow-up, 18 of them (31%) secondary to spontaneous bacterial peritonitis. The 1-year survival probability in the whole series of patients was 38%.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
28.
Clinical need for antidiuretic hormone antagonists in cirrhosis 总被引:3,自引:0,他引:3
29.
Yañez-Mó M Barreiro O Gonzalo P Batista A Megías D Genís L Sachs N Sala-Valdés M Alonso MA Montoya MC Sonnenberg A Arroyo AG Sánchez-Madrid F 《Blood》2008,112(8):3217-3226
MT1-MMP plays a key role in endothelial function, as underscored by the angiogenic defects found in MT1-MMP deficient mice. We have studied the molecular interactions that underlie the functional regulation of MT1-MMP. At lateral endothelial cell junctions, MT1-MMP colocalizes with tetraspanin CD151 (Tspan 24) and its associated partner alpha3beta1 integrin. Biochemical and FRET analyses show that MT1-MMP, through its hemopexin domain, associates tightly with CD151, thus forming alpha3beta1 integrin/CD151/MT1-MMP ternary complexes. siRNA knockdown of HUVEC CD151 expression enhanced MT1-MMP-mediated activation of MMP2, and the same activation was seen in ex vivo lung endothelial cells isolated from CD151-deficient mice. However, analysis of collagen degradation in these experimental models revealed a diminished MT1-MMP enzymatic activity in confined areas around the cell periphery. CD151 knockdown affected both MT1-MMP subcellular localization and its inclusion into detergent-resistant membrane domains, and prevented biochemical association of the metalloproteinase with the integrin alpha3beta1. These data provide evidence for a novel regulatory role of tetraspanin microdomains on the collagenolytic activity of MT1-MMP and indicate that CD151 is a key regulator of MT1-MMP in endothelial homeostasis. 相似文献
30.
Paolo Angeli Guillermo Fernández-Varo Virna Dalla Libera Silvano Fasolato Alessandra Galioto Vicente Arroyo Antonietta Sticca Silvia Guarda Angelo Gatta Wladimiro Jiménez 《Liver international》2005,25(2):429-437
BACKGROUND: The role of nitric oxide (NO) in the pathogenesis of splanchnic arterial vasodilation in cirrhosis has been recently debated by some experimental studies. AIMS: We investigated the role of NO in the pathogenesis of the splanchnic arterial vasodilation along the course of CCl(4)-induced experimental cirrhosis. METHODS: We analyzed the effect on mean arterial pressure (MAP), cardiac output (CO), total peripheral resistance (TPR), and resistance in the superior mesenteric artery (RSMA), before and after the administration of a unspecific NO synthase (NOS) inhibitor (Nomega-nitro-L-arginine-methyl-ester, L-NAME) and a specific NOS2 inhibitor (L-N-(1-iminoethyl)-lysine, L-NIL) to cirrhotic rats with and without ascites, and to control rats. NOS2 and NOS3 protein expression was also assessed in systemic and splanchnic arteries of these animals. RESULTS: L-NAME in cirrhotic rats markedly improved MAP, and TPR and decreased CO regardless of whether they had ascites or not. L-NIL did not produce any significant effect on systemic haemodynamics in control and cirrhotic rats. NOS3 overexpression in the aorta of cirrhotic animals paralleled the progression of the liver disease. L-NAME increased RSMA in cirrhotic rats, but this effect was much less intense in rats with ascites. L-NIL had an effect only on RSMA in rats with ascites, which was of a similar extent to that produced by L-NAME. Western blot experiment showed a faint overexpression of NOS3 in the mesenteric artery of cirrhotic rats with and without ascites and a clear induction of NOS2 only in the mesenteric artery of rats with ascites. Conclusions: These results indicate that NO contributes significantly to the pathogenesis of arterial splanchnic circulation in the early stages of experimental cirrhosis but has only a minor role in its maintenance after the development of ascites. Furthermore, the expression of the different NOS isoforms varies along the course of the liver disease. 相似文献