全文获取类型
收费全文 | 1741532篇 |
免费 | 141673篇 |
国内免费 | 2743篇 |
专业分类
耳鼻咽喉 | 23850篇 |
儿科学 | 57723篇 |
妇产科学 | 49669篇 |
基础医学 | 248943篇 |
口腔科学 | 51434篇 |
临床医学 | 154996篇 |
内科学 | 339928篇 |
皮肤病学 | 37938篇 |
神经病学 | 144727篇 |
特种医学 | 70063篇 |
外国民族医学 | 474篇 |
外科学 | 263332篇 |
综合类 | 40456篇 |
现状与发展 | 4篇 |
一般理论 | 610篇 |
预防医学 | 132639篇 |
眼科学 | 39568篇 |
药学 | 131111篇 |
3篇 | |
中国医学 | 3169篇 |
肿瘤学 | 95311篇 |
出版年
2018年 | 18214篇 |
2017年 | 14518篇 |
2016年 | 16435篇 |
2015年 | 18185篇 |
2014年 | 24338篇 |
2013年 | 37458篇 |
2012年 | 50839篇 |
2011年 | 53910篇 |
2010年 | 31422篇 |
2009年 | 29024篇 |
2008年 | 51825篇 |
2007年 | 54465篇 |
2006年 | 54885篇 |
2005年 | 53465篇 |
2004年 | 52214篇 |
2003年 | 50203篇 |
2002年 | 49119篇 |
2001年 | 79601篇 |
2000年 | 83224篇 |
1999年 | 69278篇 |
1998年 | 19182篇 |
1997年 | 17479篇 |
1996年 | 17222篇 |
1995年 | 16825篇 |
1994年 | 15821篇 |
1993年 | 14941篇 |
1992年 | 56077篇 |
1991年 | 54346篇 |
1990年 | 53082篇 |
1989年 | 51377篇 |
1988年 | 47658篇 |
1987年 | 47054篇 |
1986年 | 44692篇 |
1985年 | 43420篇 |
1984年 | 32615篇 |
1983年 | 28049篇 |
1982年 | 16676篇 |
1981年 | 14920篇 |
1979年 | 30873篇 |
1978年 | 21441篇 |
1977年 | 18163篇 |
1976年 | 17038篇 |
1975年 | 17917篇 |
1974年 | 21817篇 |
1973年 | 20936篇 |
1972年 | 19076篇 |
1971年 | 18001篇 |
1970年 | 16510篇 |
1969年 | 15468篇 |
1968年 | 14148篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
No impact of repeated endoscopic screens on gastric cancer mortality in a prospectively followed Chinese population at high risk. 总被引:6,自引:0,他引:6
B Riecken R Pfeiffer J L Ma M L Jin J Y Li W D Liu L Zhang Y S Chang M H Gail W C You 《Preventive medicine》2002,34(1):22-28
BACKGROUND: Gastric cancer (GC) is the leading cause of cancer deaths in China. Our study prospectively evaluated the impact of repeated endoscopic screens on GC mortality in a high-risk population in China. METHODS: Between 1989 and 1999, a population-based gastroscopic screening was conducted in 4,394 residents of Linqu County, China, a region with the highest rates of GC worldwide. Residents ages 35 to 64 years received initial gastroscopies with biopsies in 1989. Repeated endoscopies were performed in 1994 and 1999. Cancer occurrences and deaths were actively monitored throughout the entire period until July 2000. Mortality from GC was compared with expected values based on mortality rates obtained for Linqu in the 1990-1992 Chinese Cancer Mortality Survey. RESULTS: Between March 1989 and July 2000, 39,303 person-years were accumulated; 85 new GCs occurred, 29 (34.5%) were in early stage. Fifty-eight cases (68%) were identified at one of the screens. The number of observed deaths from GC (37) was close to the expected (36.8). The standardized mortality ratio was 1.01 (95% CI 0.72-1.37) for the entire cohort, 1.13 (95% CI 0.77-1.57) for males, and 0.65 (95% CI 0.26-1.32) for females. CONCLUSIONS: Despite high population coverage with repeated screens, no reduction in GC mortality was observed in this high-risk population in China. 相似文献
992.
Joseph M Dhahbi Shelley X Cao Patricia L Mote Brian C Rowley John E Wingo Stephen R Spindler 《The Journal of nutrition》2002,132(1):31-37
Molecular chaperones assist in the biosynthesis and processing of proteins. Most chaperones are induced by physiological stresses. We have shown that dietary energy restriction decreases the mRNA and protein levels of many endoplasmic reticulum chaperones in the livers of mice. Here, we have investigated the response of chaperone mRNA to feeding. Control and 50% energy-restricted C3B10RF1 mice were deprived of food for 24 h, fed, and killed 0, 1.5, 5 or 12 h after feeding. Chaperone mRNAs were strongly induced as early as 1.5 h after feeding in control and energy-restricted mice. The integrated levels of these mRNA over 24 h were significantly lower in energy-restricted mice. The mRNA response to energy intake was mirrored over the course of days in the level of chaperone protein. A similar but smaller response to feeding was found in kidney and muscle. Puromycin and cycloheximide failed to inhibit the feeding response, suggesting that feeding releases chaperone expression from an unstable inhibitor. Studies with dibutyryl-cAMP- and glucagon-supplemented, normal and streptozotocin-diabetic mice suggest that glucagon and insulin may be mediators of the feeding response. Adrenalectomy enhanced the feeding induction, but dexamethasone administration had no effect. Thus, postprandial changes in insulin and glucagon may link chaperone gene expression to feeding, possibly in several tissues including liver. 相似文献
993.
994.
R. M. Konrad 《Langenbeck's archives of surgery / Deutsche Gesellschaft fur Chirurgie》1980,352(1):293
Zusammenfassung Anhand von 678 bis Ende 1979 operierten Patienten mit Lungenerkrankungen wird die technische Anwendung automatischer Nahtgeräte demonstriert. Sie eignen sich zum Bronehusverschluß, für Keilexcisionen sowie zum Verschluß von Lungenvenen. Technische Modalitäten sind zu beachten. Der Vorteil liegt bei sachgemäßem Vorgehen in der Sicherheit der Anwendung, der Effektivität und in der kürzeren Operationszeit. Die Insuffizienzquote beträgt einschl. der Anfangszeit 4,4% in der Spätphase 3,2%. Komplikationen bei Keilexcisionen treten ebensowenig auf wie beim Verschluß der Lungenvenen. 相似文献
995.
Å. Öst P. Lindström B. Christensson H. Gyllenhammar L. Engstedt 《European journal of haematology》1984,33(2):160-170
A consecutive series of patients (1978–1981) comprising all patients with acute leukaemia from a population of 475000 inhabitants was reviewed. Thus, 94 patients were diagnosed as having acute leukaemia. No patients were lost from follow-up. The incidence figures of ALL and AML differed significantly from those of Sweden as a whole. 9 patients were < 15 years old. The median age of adult patients was 64 years, 60.8% being ≥ 60 years old. Of adult patients with AML, 20% had a preleukaemic history (chronic myeloproliferative disorders, myelodysplastic syndromes and others). None of 6 patients with leukaemia as a metamorphosis of a chronic myeloproliferative disorder achieved a complete remission. The overall remission rate of the remaining adult patients was 25%. Treated patients, 15–39 years old, with AML without any preleukaemic history, had a complete remission rate of 80% compared to 12% for patients ≥ 60 years old with the same diagnosis. Of 60 patients with ‘primary’ AML, 14 were not treated, mainly because of advanced age and complicating diseases. Most of these patients died within a week of admission. 相似文献
996.
Three cases of enteritis necroticans seen at Port Moresby General Hospital are described. All three cases proved diagnostic problems and in all three the diagnosis was made only at laparotomy. While the condition is uncommon in Port Moresby, these cases indicate that it must now be considered earlier rather than later. 相似文献
997.
A 19 years old, male patient presented with symptoms of smoky urine for 2 weeks, puffiness of face and diminished urine output for 3 weeks associated with occasional lower abdominal and flank pain. Patient's history, clinical findings and available investigations were strongly suggestive of Idiopathic Rapidly Progressive Glomerulonephritis. The patient showed excellent response to glucocorticoid and cytotoxic agent. 相似文献
998.
Changes in outcome with sphincter preserving surgery for rectal cancer in Korea, 1991-2000. 总被引:3,自引:0,他引:3
S-B Lim S C Heo M R Lee S-B Kang Y J Park K J Park H S Choi S-Y Jeong J-G Park 《European journal of surgical oncology》2005,31(3):242-249
AIM: To report the clinical and oncological data of patients operated on for rectal cancers 3-5 cm from the AV over a 10 year period, including the Sphincter preservation (SP) rate. METHODS: We reviewed medical records of 304 patients with rectal cancers 3-5 cm from the AV who underwent surgical resection from January 1991 through December 2000. The 10 years were divided into three periods based on the introduction of new surgical techniques, specifically, ultralow anterior resection (ULAR) with double stapling in March 1994 and ULAR with coloanal anastomosis in April 1997. The rates of SP, complications and patient survival during these periods were compared. RESULTS: The SP rate increased significantly over the 10 years, from 16.4% in period I (January 1991-February 1994), to 53.0% in period II (March 1994-March 1997), to 86.5% in period III (April 1997-December 2000) (p<0.001). Over time, the age of the patients increased (p=0.004), the length of the distal resection margin became shorter (p=0.005), and the rate of lymph node metastasis increased (p=0.016). The factors significantly influencing SP were the period (p<0.001) and the distance from the AV (p<0.001). Over time, morbidity did not increase, and overall and disease free survival rates did not decrease. In contrast, the overall survival of N2 cases significantly increased over time (p=0.0492). CONCLUSION: Over 10 years, the SP rate in rectal cancers 3-5 cm from the AV was significantly increased by the introduction of the double stapling and coloanal anastomosis techniques. These surgical methods, however, had no effect on morbidity, disease free survival and overall survival rates. 相似文献
999.
Dose-response curves of angiotensin I (AI, 1.0-1000.0 pmol) and angiotensin II (AII, 1.25-1250.00 pmol) were obtained in isolated rat hearts subjected to control conditions, mild hypoxia (PO2 = 145 mm Hg), reoxygenation, ischemic (perfusion pressure = 35 mm Hg) and reperfusion. Both AI and AII caused dose-dependent coronary flow (CF) of 26 +/- 3 and 27 +/- 2%, respectively. The effects of both AI and AII were substantially attenuated during hypoxia, but were fully restored upon reoxygenation. During ischemia, the effect of AII was unaltered while the effect of AI was enhanced compared to the control (P less than 0.05). This enhancement was reversible on reperfusion. Cardiac conversion of AI, calculated from ED50 values for AI and AII, was significantly increased during ischemia (P less than 0.05). Infusion of saralasin (0.5-5.0 micrograms/min) did not increase CF in any of the groups. We conclude that (1) the coronary vasoconstrictive effect of AII is preserved in ischemia but attenuated in hypoxia and (2) cardiac conversion of AI to AII is enhanced in hearts injured by ischemia. 相似文献
1000.
R S Cromartie 《The Journal of the Florida Medical Association》1991,78(12):815-817
Pollution of Florida's waterways is a serious problem. Sources of pollution include sewage, storm water runoff, faulty septic tanks, improperly constructed landfills, and obstruction by causeway bridges. Some of the major causes and solutions are discussed. 相似文献