全文获取类型
收费全文 | 3619955篇 |
免费 | 256318篇 |
国内免费 | 9483篇 |
专业分类
耳鼻咽喉 | 48837篇 |
儿科学 | 120043篇 |
妇产科学 | 99495篇 |
基础医学 | 508659篇 |
口腔科学 | 102163篇 |
临床医学 | 331512篇 |
内科学 | 705850篇 |
皮肤病学 | 85382篇 |
神经病学 | 292943篇 |
特种医学 | 137357篇 |
外国民族医学 | 941篇 |
外科学 | 540561篇 |
综合类 | 77820篇 |
现状与发展 | 8篇 |
一般理论 | 1392篇 |
预防医学 | 277157篇 |
眼科学 | 83951篇 |
药学 | 264270篇 |
12篇 | |
中国医学 | 8002篇 |
肿瘤学 | 199401篇 |
出版年
2019年 | 28696篇 |
2018年 | 40903篇 |
2017年 | 31171篇 |
2016年 | 35477篇 |
2015年 | 40190篇 |
2014年 | 55613篇 |
2013年 | 83112篇 |
2012年 | 112060篇 |
2011年 | 118601篇 |
2010年 | 71004篇 |
2009年 | 67420篇 |
2008年 | 110415篇 |
2007年 | 117557篇 |
2006年 | 119157篇 |
2005年 | 114319篇 |
2004年 | 109997篇 |
2003年 | 105789篇 |
2002年 | 102191篇 |
2001年 | 175794篇 |
2000年 | 179947篇 |
1999年 | 151339篇 |
1998年 | 43017篇 |
1997年 | 37886篇 |
1996年 | 38005篇 |
1995年 | 36855篇 |
1994年 | 33699篇 |
1993年 | 31582篇 |
1992年 | 117145篇 |
1991年 | 112977篇 |
1990年 | 109361篇 |
1989年 | 105642篇 |
1988年 | 96615篇 |
1987年 | 94626篇 |
1986年 | 88827篇 |
1985年 | 84819篇 |
1984年 | 63235篇 |
1983年 | 53676篇 |
1982年 | 31475篇 |
1981年 | 28064篇 |
1979年 | 55947篇 |
1978年 | 39285篇 |
1977年 | 33432篇 |
1976年 | 31155篇 |
1975年 | 32985篇 |
1974年 | 39355篇 |
1973年 | 37600篇 |
1972年 | 35136篇 |
1971年 | 32606篇 |
1970年 | 30126篇 |
1969年 | 28792篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Williamson Kathleen A.; Hever Ann M.; Rainger Joe; Rogers R. Curtis; Magee Alex; Fiedler Zdenek; Keng Wee Teik; Sharkey Freddie H.; McGill Niolette; Hill Clare J.; Schneider Adele; Messina Mario; Turnpenny Peter D.; Fantes Judy A.; van Heyningen Veronica; FitzPatrick David R. 《Human molecular genetics》2006,15(12):2030
Table 1 相似文献
993.
H. S. Tilney R. E. Lovegrove S. Purkayastha A. G. Heriot A. W. Darzi P. P. Tekkis 《Colorectal disease》2006,8(5):441-450
AIM: The present meta-analysis aims to compare short-term and long-term outcomes in patients undergoing laparoscopic or open subtotal colectomy for benign and malignant disease. METHODS: A literature search of Medline, Ovid, Embase and Cochrane databases was performed to identify studies published between 1992 and 2005, comparing laparoscopic (LSC) and open (OSC) subtotal colectomy. A random effect meta-analytical technique was used and sensitivity analysis performed on studies published since the beginning of 2000, higher quality papers, those reporting on more than 40 patients, and those studies reporting on adult cases or acute colitis. RESULTS: A total of eight studies satisfied the criteria for inclusion. These included outcomes on 336 patients, 143 (42.6%) of whom had undergone laparoscopic resection, with an overall conversion rate to open surgery of 5% (range 0-11.8%). Operative time was significantly longer in the laparoscopic group by 86.2 min (P < 0.001) and throughout subgroup analysis, although it was only in patients with acute colitis that this finding was without significant heterogeneity. Operative blood loss was less in the laparoscopic group by 57.5 millilitres in high quality and studies published since 2000, and 65.3 millilitres in those reporting on more than 40 patients. There was no significant difference in early or long-term complications between the groups. A statistically significant reduction in length of postoperative stay was observed in the laparoscopic groups by 2.9 days (P < 0.001). CONCLUSION: Laparoscopic subtotal colectomy was associated with longer operating times but a reduced length of stay compared to open surgery. Although short-term outcomes were equivalent in both groups, the suggested benefits in terms of reduced long-term obstructive complications were not supported by this meta-analysis. 相似文献
994.
C. J. M. Antens M. Oldenwening A. Wolse U. Gehring H. A. Smit R. C. Aalberse M. Kerkhof J. Gerritsen J. C. de Jongste B. Brunekreef 《Clinical and experimental allergy》2006,36(12):1525-1531
BACKGROUND: Studies of the association between indoor allergen exposure and the development of allergic diseases have often measured allergen exposure at one point in time. OBJECTIVE: We investigated the variability of house dust mite (Der p 1, Der f 1) and cat (Fel d 1) allergen in Dutch homes over a period of 8 years. METHODS: Data were obtained in the Dutch PIAMA birth cohort study. Dust from the child's mattress, the parents' mattress and the living room floor was collected at four points in time, when the child was 3 months, 4, 6 and 8 years old. Dust samples were analysed for Der p 1, Der f 1 and Fel d 1 by sandwich enzyme immuno assay. RESULTS: Mite allergen concentrations for the child's mattress, the parents' mattress and the living room floor were moderately correlated between time-points. Agreement was better for cat allergen. For Der p 1 and Der f 1 on the child's mattress, the within-home variance was close to or smaller than the between-home variance in most cases. For Fel d 1, the within-home variance was almost always smaller than the between-home variance. Results were similar for allergen levels expressed per gram of dust and allergen levels expressed per square metre of the sampled surface. Variance ratios were smaller when samples were taken at shorter time intervals than at longer time intervals. CONCLUSION: Over a period of 4 years, mite and cat allergens measured in house dust are sufficiently stable to use single measurements with confidence in epidemiological studies. The within-home variance was larger when samples were taken 8 years apart so that over such long periods, repetition of sampling is recommended. 相似文献
995.
C. Olgart Höglund J. Axén C. Kemi S. Jernelöv J. Grunewald C. Müller-Suur Y. Smith R. Grönneberg A. Eklund P. Stierna M. Lekander 《Clinical and experimental allergy》2006,36(8):982-992
BACKGROUND: Stress can aggravate the allergic inflammation, but determinants of disturbed immune regulation are largely unknown. OBJECTIVE: To determine systemic immunological, local inflammatory and functional airway responses to stress in healthy and atopic individuals. METHODS: Forty-one undergraduate students, 22 with allergy of whom 16 had asthma, and 19 healthy controls, were studied in a low-stress period and in association with a large exam. Subjects completed questionnaires on stress and health behaviours, underwent lung function tests, bronchial methacholine challenge, measurements of exhaled nitric oxide and urine cortisol. Blood cells were phenotyped, and cytokines from mononuclear blood cells were analysed. RESULTS: Perceived stress and anxiety increased in both groups during the exam period while cortisol increased only in the atopy group. Cytokine production decreased broadly in response to stress in both groups, which was paralleled by an increase in the proportion of regulatory T cells (CD4(+)CD45RO(+)CD25(bright)). Interestingly, atopic individuals, but not controls, reacted with a decreased T-helper type 1/T-helper type 2 (Th1/Th2) ratio and a decrease in natural killer (NK) cell numbers in response to stress. In control subjects only, exhaled nitric oxide decreased and forced expiratory volume in one second increased during stress. CONCLUSION: Atopic and non-atopic subjects shared some immune changes in response to stress, such as a dramatic decline in cytokines and an increase in the number of regulatory T cells in peripheral blood. However, other stress-induced immune changes were unique to atopic individuals, such as a skewed Th1/Th2 ratio and reduced NK cell numbers, indicating that some pathogenic mechanisms in atopics may be more strongly affected by stress than others. 相似文献
996.
997.
W. M. Tilakaratne 《Journal of oral pathology & medicine》2006,35(1):61-63
The term synovial sarcoma was first proposed for the histologically well defined entity by Knox in 1936. The name was proposed due to the fact that at least the cases reported in the early part showed some resemblance of the tumour to normal synovial tissue histologically. Thereafter, tumours have been diagnosed from areas without synovial tissue. The diagnosis of monophasic tumours can be difficult and immunostains appear to be a good diagnostic tool in those cases. The occurrence in the mandible is extremely rare. This is a case of synovial sarcoma arising in the condyle involving most of the ramus. The tumour was diagnosed as synovial sarcoma with predominant spindle cell component by correlation of histopathology with immunostains (cytokeratin, epithelial membrane antigen, actin and desmin). The patient has been treated with surgery and radiotherapy. 相似文献
998.
Dnyanesh N Tipre James J Fox Daniel P Holt Gilbert Green Jianhua Yu Martin Pomper Robert F Dannals Frank M Bengel 《Journal of nuclear medicine》2008,49(7):1189-1195
The sympathetic nervous system of the heart plays a key role in the pathophysiology of various cardiac diseases. Small-animal models are valuable for obtaining further insight into mechanisms of cardiac disease and therapy. To determine the translational potential of cardiac neuronal imaging from rodents to humans, we characterized the rat sympathetic nervous system using 3 radiotracers that reflect different subcellular mechanisms: (11)C-meta-hydroxyephedrine (HED), a tracer of neuronal transport showing stable uptake and no washout in healthy humans; (11)C-phenylephrine (PHEN), a tracer of vesicular leakage and intraneuronal metabolic degradation with initial uptake and subsequent washout in humans; and (11)C-epinephrine (EPI), a tracer of vesicular storage with stable uptake and no washout in humans. METHODS: We used a small-animal PET system to study healthy male Wistar rats at baseline, after desipramine (DMI) pretreatment (DMI block), and with DMI injection 15 min after tracer delivery (DMI chase). The rats were kept under general isoflurane anesthesia while dynamic emission scans of the heart were recorded for 60 min after radiotracer injection. A myocardial retention index was determined by normalizing uptake at 40 min to the integral under the arterial input curve. Washout rates were determined by monoexponential fitting of myocardial time-activity curves. RESULTS: At baseline, HED showed high myocardial uptake and sustained retention, EPI showed moderate uptake and significant biphasic washout, and PHEN showed moderate uptake and monoexponential washout. The average (+/- SD) left ventricular retention index for HED, PHEN, and EPI was 7.38% +/- 0.82%/min, 3.43% +/- 0.45%/min, and 4.24% +/- 0.59%/min, respectively; the washout rate for HED, PHEN, and EPI was 0.13% +/- 0.23%/min, 1.13% +/- 0.35%/min, and 0.50% +/- 0.24%/min, respectively. The DMI chase resulted in increased washout only for HED. DMI block decreased myocardial uptake of all tracers by less than 90%. CONCLUSION: Kinetic profiles of HED in the rat myocardium were similar to those of HED in humans, suggesting comparable neuronal transport density. Unlike in humans, however, significant washout of EPI and faster washout of PHEN were encountered, consistent with high intraneuronal metabolic activity, high catecholamine turnover, and reduced vesicular storage. This evidence of increased neuronal activity in rodents has implications for translational studies of cardiac neuronal biology in humans. 相似文献
999.
1000.