全文获取类型
收费全文 | 6196篇 |
免费 | 410篇 |
国内免费 | 89篇 |
专业分类
耳鼻咽喉 | 71篇 |
儿科学 | 250篇 |
妇产科学 | 143篇 |
基础医学 | 847篇 |
口腔科学 | 64篇 |
临床医学 | 864篇 |
内科学 | 1144篇 |
皮肤病学 | 122篇 |
神经病学 | 498篇 |
特种医学 | 466篇 |
外科学 | 712篇 |
综合类 | 93篇 |
一般理论 | 3篇 |
预防医学 | 479篇 |
眼科学 | 151篇 |
药学 | 386篇 |
中国医学 | 7篇 |
肿瘤学 | 395篇 |
出版年
2021年 | 81篇 |
2020年 | 53篇 |
2019年 | 94篇 |
2018年 | 88篇 |
2017年 | 71篇 |
2016年 | 76篇 |
2015年 | 113篇 |
2014年 | 113篇 |
2013年 | 189篇 |
2012年 | 238篇 |
2011年 | 250篇 |
2010年 | 170篇 |
2009年 | 174篇 |
2008年 | 213篇 |
2007年 | 259篇 |
2006年 | 241篇 |
2005年 | 221篇 |
2004年 | 240篇 |
2003年 | 206篇 |
2002年 | 204篇 |
2001年 | 181篇 |
2000年 | 177篇 |
1999年 | 189篇 |
1998年 | 144篇 |
1997年 | 116篇 |
1996年 | 110篇 |
1995年 | 99篇 |
1994年 | 86篇 |
1993年 | 78篇 |
1992年 | 131篇 |
1991年 | 115篇 |
1990年 | 137篇 |
1989年 | 135篇 |
1988年 | 124篇 |
1987年 | 112篇 |
1986年 | 122篇 |
1985年 | 107篇 |
1984年 | 82篇 |
1983年 | 60篇 |
1982年 | 57篇 |
1981年 | 50篇 |
1980年 | 45篇 |
1979年 | 88篇 |
1978年 | 64篇 |
1977年 | 70篇 |
1976年 | 62篇 |
1975年 | 48篇 |
1974年 | 47篇 |
1973年 | 55篇 |
1972年 | 50篇 |
排序方式: 共有6695条查询结果,搜索用时 15 毫秒
91.
PURPOSE: To present the imaging findings and treatment options for incomplete intertrochanteric fractures. MATERIALS AND METHODS: Among 31 patients with the magnetic resonance (MR) imaging diagnosis of incomplete intertrochanteric fracture, 30 also underwent radiography. MR and radiographic findings were compared. Note was made of fracture length and extent as depicted on the coronal and axial MR images, treatment (surgical vs conservative), and follow-up. RESULTS: Correlation between radiographic and MR findings was poor. Incomplete intertrochanteric fracture was the prospective radiographic diagnosis in only one case. Fracture in 18 patients was treated surgically and in 13 was managed conservatively. In both groups, the average age of the patients and length of the fractures and the percentage of separate fractures involving the greater trochanter and crossing the midline of the femur in the axial plane were the same. Fractures crossed the midline in the coronal plane in 50% of the surgical group but in only 23% of the nonsurgical group. Average time from injury to ambulation was 2 days less in the surgical group, but no difference in functional status was found subjectively between the two groups at clinical follow-up. CONCLUSION: Incomplete intertrochanteric fractures are a previously unrecognized subset of intertrochanteric fractures that are diagnosed unequivocally only with MR imaging. 相似文献
92.
93.
94.
J. M. Swann T. W. Schultz J. R. Kennedy 《Archives of environmental contamination and toxicology》1996,30(2):188-194
The ciliotoxic potential of the organophosphorous insecticides Dursban and Lorsban, their active ingredient, chlorpyrifos, and their carrier ingredients (Blanks) were assessed. Since chlorpyrifos inhibits acetylcholinesterase, the acetylcholine-innervated ciliated epithelial cultures of frog palate were used as the model. All compounds caused a decrease in frequency of ciliary beat over time. EC50 values followed the same order as the time to inhibition. The orders were Lorsban > Dursban > chlorpyrifos, and Lorsban > Dursban Lorsban Blank > Dursban Blank. Stimulation of ciliary beating occurred immediately after exposure to all compounds, followed by inhibition. Dursban, Lorsban, and both Blanks elicited stimulatory effects in the presence of atropine. Atropine only blocked the initial stimulatory response with chlorpyrifos. In addition to chlorpyrifos, some component(s) of the inert ingredients were initially stimulatory but ultimately inhibitory to ciliary beating in the frog palate model. All compounds caused mitochondrial damage, including swelling, disruption of cristae, and loss of matrix. 相似文献
95.
P Menyuk J Liebergott M Schultz M Chesnick L Ferrier 《Journal of speech and hearing research》1991,34(1):88-94
The linguistic and cognitive development of 26 premature and 27 full-term infants was studied longitudinally over the first 3 years of life. Infants in the premature population included 12 who were below 1500 g in birthweight and an even larger number with "at risk" signs. Language samples were collected in the home approximately every other month, the children were given experimenter-designed tests periodically, and mothers were asked to keep diaries of their children's lexical development. The children were given standardized tests as they exited the study. Cognitive development was also measured periodically. The patterns of lexical and cognitive development of the prematures did not differ markedly from those of full-term infants. There were no significant differences between the prematures as a whole and the full-term infants on standard language test measures as they exited from the study. There were significant differences between the very low birthweight and full-term infants on two of the exit measures. However, the performance of the very low birthweight infants was well within the range of normal on these two measures. The nature of the study and the factors that might have led to lack of differences between the two groups are discussed. 相似文献
96.
The education of a mother is strongly and positively correlated with the survival rate of her children. This paper combines household data from the Colombian Census of 1973 and characteristics of the 900 residential areas in Colombia, to test various hypotheses concerning the mechanism by which mother's education and public policies affect child survival and the distribution of health benefits resulting from policy interventions. The hypothesis is advanced that education provides people with skills in acquiring and decoding new information and thus effectively lowers the costs of using more beneficial child health and contraceptive technologies. Since a primary function of health and family planning programs is to disseminate information on these same technologies, the hypothesis is tested that mother's education and these program interventions may substitute for each other in improving child health and reducing family size. The empirical analysis confirms that in urban areas the availability of medical services, family planning activities, transportational infrastructure and climate, in addition to mother's education, are associated with child mortality ratios and fertility within a birth cohort of mothers. The least educated mothers are the most strongly affected, in terms of their reduced fertility and increased child survival rates, by the local urban health programs. The evidence is, thus, consistent with the substitution hypothesis. No effects of program interventions and medical facilities are found on rural populations, though both child mortality ratios and fertility are lower for more educated rural women. 相似文献
97.
Summary GTP is generally required for hormonal stimulation of adenylate cyclase. On the other hand, the presence of GTP is essential for hormone-induced inhibition of adenylate cyclase in cell-free preparations of human platelets and other cells. In order to differentiate the dual roles of GTP in hormonal stimulation and inhibition of adenylate cyclase, we have studied the effect of adrenaline on the platelet enzyme under conditions where guanine mucleotides caused marked stimulation. In the presence of GTP (1 M), which by itself had no or only a small stimulatory effect on adenylate cyclase, adrenaline inhibited the basal and prostaglandin E1-stimulated forms of the enzyme. In contrast, the stable GTP analogues, GMP-P(NH)P and GTP--S, which caused a time-dependent, persistent activation of the enzyme, reversed or prevented the inhibitory effect of adrenaline. Cholera toxin, which activates adenylate cyclase presumably by inhibition of a specific GTPase, increased cyclase activity in platelet membranes up to 4-fold, and GTP addition (0.1–30 M) augmented this activation about 2-fold. The -adrenergic component of adrenaline (0.1–100 M), in a concentration-dependent manner, prevented the GTP-induced increase in cholera toxin-stimulated activity. The inhibition was also observed in enzyme preparations that had been fully activated by pretreatment with cholera toxin. These data suggest that -adrenergic agonists may inhibit platelet adenylate cyclase through increased inactivation of the enzyme, possibly involving a stimulation of the GTPase connected to the adenylate cyclase system.Abbreviations GMP-P(NH)P
guanylyl 5-imidodiphosphate
- GTP--S
guanosine 5-(-thio)triphosphate
- GTPase
guanosine 5-triphosphatase
- Pi
inorganic phosphate.
Parts of the data were presented in preliminary form (Jakobs and Schultz, 1978) 相似文献
98.
S Imber E Schultz F Funderburk R Allen R Flamer 《The Journal of nervous and mental disease》1976,162(4):238-247
Eighty-three male alcoholics were administered a structured interview when they appeared at a large general hospital for treatment of a variety of disorders. These represent 83 consecutive cases. None received treatment aside from brief "drying-out" but all were accepted as participants in a research program. Seventy-three (88 per cent of the sample) were located for a 3-year follow-up; five of these were not seen at the 1-year follow-up, and 10 were known to be dead. This paper focuses on 58 of the alcoholics who were seen at all three evaluations, and the 10 who were known dead. The data are presented as indicating the long term results of, at best, a mild or minimal intervention with male alcoholics. A small, but significant improvement was noted on several life-adjustment scales between the initial and 1-year evaluation (OYE), but no further improvement was seen between OYE and the 3-year evaluation (TYE); 19 percent were abstinent for 1 year and 10 per cent for the full 3-year period. The best predictor of TYE abstinence was OYE abstinence, but only for the extremes, i.e., no abstinence or total abstinence. Abstinence success was also related to a tendency to use community resources, lower number of mental hospitalizations, higher occupational status, higher global rating and, curiously, lower interpersonal adjustment rating. The group using Alcoholics Anonymous showed no better outcome than the group using no community resources at all. The mortality rate was 12 per cent over the 3 years or slightly more than 4 per cent a year. The suicide rate was about 4 per cent over the 3 years. The ratings for those dying showed a pattern of more admitted drunken arrests and heavy recent drinking superimposed on lighter overall drinking for the past year. The study demonstrates that even untreated alcoholics can be traced and effective follow-up studies completed. Results also indicate that over long time periods and left to their own devices, many alcoholics do seek out some form of help. But such assistance tends not to be sustained or intensive and a good portion of it is nonprofessional and nonmedical. Moreover, a surprisingly substantial number (31 per cent) of hospital-identified alcoholics apparently neither seek out nor receive any help at all after their initial identification; yet their self-reported life-adjustment ratings do not differ significantly from those who do seek help. The no-help receivers may be the most critical group of all to follow, as they are trule untreated. It would be important to determine how consistent in fact they are in their avoidance of help, what accounts for that behavior, and whether their ultimate fate is different from those who regularly seek assistance. 相似文献
99.
Asperger's disorder 总被引:1,自引:0,他引:1
Volkmar FR Klin A Schultz RT Rubin E Bronen R 《The American journal of psychiatry》2000,157(2):262-267
100.