全文获取类型
收费全文 | 841篇 |
免费 | 49篇 |
国内免费 | 18篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 17篇 |
妇产科学 | 24篇 |
基础医学 | 83篇 |
口腔科学 | 10篇 |
临床医学 | 102篇 |
内科学 | 197篇 |
皮肤病学 | 6篇 |
神经病学 | 50篇 |
特种医学 | 170篇 |
外科学 | 102篇 |
综合类 | 16篇 |
一般理论 | 3篇 |
预防医学 | 55篇 |
眼科学 | 9篇 |
药学 | 34篇 |
中国医学 | 4篇 |
肿瘤学 | 23篇 |
出版年
2022年 | 3篇 |
2021年 | 18篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 8篇 |
2017年 | 9篇 |
2016年 | 8篇 |
2015年 | 13篇 |
2014年 | 14篇 |
2013年 | 27篇 |
2012年 | 43篇 |
2011年 | 51篇 |
2010年 | 24篇 |
2009年 | 29篇 |
2008年 | 34篇 |
2007年 | 61篇 |
2006年 | 55篇 |
2005年 | 39篇 |
2004年 | 35篇 |
2003年 | 51篇 |
2002年 | 41篇 |
2001年 | 28篇 |
2000年 | 28篇 |
1999年 | 29篇 |
1998年 | 13篇 |
1997年 | 11篇 |
1996年 | 15篇 |
1995年 | 10篇 |
1994年 | 9篇 |
1993年 | 6篇 |
1992年 | 20篇 |
1991年 | 21篇 |
1990年 | 16篇 |
1989年 | 28篇 |
1988年 | 20篇 |
1987年 | 19篇 |
1986年 | 12篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1975年 | 5篇 |
1973年 | 3篇 |
1972年 | 1篇 |
1967年 | 1篇 |
1961年 | 2篇 |
排序方式: 共有908条查询结果,搜索用时 15 毫秒
61.
W D Travis R I Linnoila M G Tsokos C L Hitchcock G B Cutler L Nieman G Chrousos H Pass J Doppman 《The American journal of surgical pathology》1991,15(6):529-553
Based on our review of 35 cases and the literature, we found the spectrum of pulmonary neuroendocrine (NE) tumors to be too broad to fit into the traditional three-category classification scheme of typical carcinoid (TC), atypical carcinoid (AC), and small-cell lung carcinoma (SCLC). We found that a spectrum of high- and low-grade tumors exist between TC and SCLC and that in the past many of these tumors have been called AC. We chose to adhere to Arrigoni's definition of AC, as his original criteria characterized a low-grade tumor. For the higher grade non-small-cell tumors (NSCLC), we propose a fourth category of large-cell neuroendocrine carcinoma (LCNEC), which is characterized by: (a) light microscopic NE appearance; (b) cells of large size, polygonal shape, low nuclear-cytoplasmic ratio (N:C), coarse nuclear chromatin, and frequent nucleoli; (c) high mitotic rate [greater than 10/10 high-power fields (HPF)] and frequent necrosis; and (d) NE features by immunohistochemistry (IHC) or electron microscopy (EM). Thus, after deciding that a pulmonary NE tumor is high grade, the major diagnostic issue is separation of LCNEC from SCLC. This distinction is based not only on cell size, but on a variety of morphologic features. We studied 20 TC, six AC, five LCNEC, and four SCLC and characterized the clinical, light microscopic, EM, IHC, and flow cytometric features of each type of tumor. We did not find any advantage to IHC, EM, or flow cytometry over light microscopy in the subclassification or prediction of prognosis; however, these methods were useful in characterizing these four types of pulmonary NE tumors and in demonstrating their NE properties. LCNEC must be distinguished from a fifth category pulmonary NE tumor: NSCLC with NE features in which NE differentiation is not evident by light microscopy and must be demonstrated by EM or IHC. Although the prognosis of LCNEC appears to be intermediate between AC and SCLC, larger numbers of patients will be needed to demonstrate significant differences in survival. 相似文献
62.
This article describes a convenient method of checking the delivery rate of volumetric pumps at low flow rate settings. The method employs a tester previously described for use with syringe pumps. 相似文献
63.
Strangulation in child abuse: CT diagnosis 总被引:2,自引:0,他引:2
The central nervous system is commonly affected in child abuse. Between April 1985 and July 1986 three infants were identified in whom the primary mode of injury had been strangulation. In each case computed tomography (CT) demonstrated a large cerebral infarction confined to vascular territories associated with small subdural hematomas. There was no history or visible evidence of significant head trauma. Autopsy of one infant confirmed the presence of a hemispheric infarct, thin subdural hematoma, and an area of subintimal hemorrhage in the carotid artery ipsilateral to the infarct. The remaining two patients survived with residual hemiparesis. CT findings of a large cerebral infarction with an associated subdural hematoma in an infant without a history of a significant trauma should suggest the possibility of child abuse and may be the primary manifestation of abuse in some patients. 相似文献
64.
The results of this investigation show that when direct comparisons are made between the USDA NDB and microcomputer data bases (avoiding the confounding factors of coding judgment and the differences between older and newer USDA nutrient data), differences still can exist. N3 and FP chose to seek out alternate data when the USDA NDB provided no data for a certain nutrient. FP chose to use a large number of additional sources to supplement USDA Handbook No. 8. Although the USDA NDB was very complete for all nutrients listed except for vitamin E/total and copper, gaps are likely to continue to exist because the USDA NDB is and will be in continual revision as an increasing number of nutrients are reported for an ever-growing food supply. Therefore, in accordance with established local needs, the dietitian has the responsibility both for knowing the sources used in the microcomputer nutrient data base and for making sure that reported results are reasonable. 相似文献
65.
66.
Reliability and sensitivity to change of a simplification of the Sharp/van der Heijde radiological assessment in rheumatoid arthritis. 总被引:3,自引:0,他引:3
D van der Heijde T Dankert F Nieman R Rau M Boers 《Rheumatology (Oxford, England)》1999,38(10):941-947
OBJECTIVE: To determine the reliability and sensitivity to change of a simplified radiological scoring method [simple erosion narrowing score (SENS)] for rheumatoid arthritis (RA). SENS was compared to the Sharp/van der Heijde score (SHS) as a gold standard. METHODS: Sets of seven radiographs of hands and feet were taken of 20 RA patients with a wide spectrum of radiological damage. For 14 patients, these seven radiographs were taken during a follow-up period of 5 yr, and for six patients during a follow-up of 10 yr. Each set of radiographs was scored twice by the same observer (DvdH). Erosions and joint space narrowing were scored with SHS (range 0-448) in 32 and 30 joints in the hands, respectively, and both in 12 joints in the feet. SENS gives a score of 1 if there is any erosion in a joint and also 1 if there is any narrowing in the joint (range 0-86). In each case, SENS was derived from SHS. To analyse data, generalizability theory and repeated measurements ANOVA were used. RESULTS: The overall reliability coefficient was 0.81 for SHS and 0.80 for SENS. Intra-observer reliability [intraclass correlation coefficient (ICC)] was 0.99 and 0.98 for SHS and SENS, respectively. The ICC for the sensitivity to change was 0.84 for SHS and 0.88 for SENS. The smallest detectable difference (SDD) could be determined for both methods. The presence of progression based on this SDD was very comparable between the two methods. CONCLUSION: The measurement properties of SENS are good and comparable to SHS. This makes SENS suitable for use in clinical practice and in large (epidemiological) studies, especially in the first years of disease. 相似文献
67.
M Nieman 《Journal of medical engineering & technology》1987,11(1):30-33
This article describes the failure mechanisms of nickel cadmium batteries. The design of suitable battery chargers for defibrillators is discussed. It is argued that the life of nickel cadmium battery packs can be significantly extended without impairing safety if appropriate testing is carried out. Results of tests on a set of 10 defibrillator packs removed from service after a period of two years are presented. 相似文献
68.
D C Nieman B C Underwood K M Sherman K Arabatzis J C Barbosa M Johnson T D Shultz 《Journal of the American Dietetic Association》1989,89(12):1763-1769
The purpose of this study was to investigate nutrient intakes of Seventh-Day Adventist elderly women who were similar in many demographic and life-style factors except for choice of diet. Twenty-three vegetarian and 14 non-vegetarian elderly women (mean +/- standard error ages 72.2 +/- 1.3 and 71.1 +/- 1.4 years, respectively) were recruited on the basis of several selection criteria, including race, religion, education, geographic area, Quetelet index, self-reported absence of major chronic disease and use of medications, and physical activity. Average years +/- SE of adherence to dietary regimens were 47.0 +/- 2.9 and 71.2 +/- 1.4 in the vegetarian and non-vegetarian groups, respectively. Results from analysis of 7-day food records showed that vegetarians consumed significantly less cholesterol, saturated fatty acids, and caffeine but more carbohydrate, dietary fiber, magnesium, vitamins E and A, thiamin, pantothenic acid, copper, and manganese than non-vegetarians (p less than .05). On the basis of group means, 67% of the Recommended Dietary Allowance was met for all nutrients except zinc and vitamin D in both groups, and vitamins B-6, folacin, and vitamin E in the non-vegetarians. Compared with non-vegetarians, vegetarians had significantly lower serum glucose (5.18 +/- 0.11 vs. 4.65 +/- 0.09 mmol/L), low-density-lipoprotein cholesterol (4.08 +/- 0.25 vs. 3.34 +/- 0.19 mmol/L), and total cholesterol levels (6.46 +/- 0.27 vs. 5.62 +/- 0.21 mmol/L) (p less than .05). In summary, when healthy elderly vegetarian women were compared with closely matched non-vegetarian peers, the vegetarian diet was associated with improved nutrient intake and associated reductions in blood glucose and lipid levels. 相似文献
69.
70.
Infusible platelet membrane microvesicles: a potential transfusion substitute for platelets 总被引:8,自引:0,他引:8
FC Chao ; BK Kim ; AM Houranieh ; FH Liang ; MW Konrad ; SN Swisher ; JL Tullis 《Transfusion》1996,36(6):536-542
BACKGROUND: Several substitutes for intact, viable platelets have been used for transfusion, both to people and in animal models, with varied success. Infusible platelet membrane (IPM) is prepared from human platelets. IPM retains the glycoprotein (GP)lb receptor and has platelet factor 3 activity (procoagulant activity). However, factor V, serotonin, a cytoplasmic marker enzyme (purine nucleotide phosphorylase), GPIIb/IIIa complex, and HLA class I and II antigens are all absent in IPM. STUDY DESIGN AND METHODS: IPM is prepared from outdated platelets. The platelets were disrupted by freezing and thawing; they were washed and heated to inactivate possible viral contaminants, and then the sonicated membrane microvesicle fraction was separated and lyophilized. The hemostatic activity of IPM was measured by its ability to reduce the prolonged bleeding time in thrombocytopenic rabbits. RESULTS: Administration of IPM at a dose of 2 mg per kg results in a substantial reduction in the bleeding time. In a series of 23 experiments, a median preinjection bleeding time of 15 minutes was reduced to 6 minutes within 4 hours after IPM administration. Administration of IPM did show a mild enhancement in the thrombogenicity index, as measured in the Wessler rabbit model. This enhancement is, however, not significant, as a thrombogenicity index value of up to 0.6 is clinically acceptable. CONCLUSION: IPM may have clinical potential as a substitute for platelets in the treatment of bleeding due to thrombocytopenia. 相似文献