全文获取类型
收费全文 | 7412篇 |
免费 | 411篇 |
国内免费 | 32篇 |
专业分类
耳鼻咽喉 | 76篇 |
儿科学 | 281篇 |
妇产科学 | 160篇 |
基础医学 | 692篇 |
口腔科学 | 176篇 |
临床医学 | 575篇 |
内科学 | 1662篇 |
皮肤病学 | 172篇 |
神经病学 | 488篇 |
特种医学 | 185篇 |
外科学 | 1552篇 |
综合类 | 118篇 |
一般理论 | 2篇 |
预防医学 | 273篇 |
眼科学 | 246篇 |
药学 | 625篇 |
中国医学 | 34篇 |
肿瘤学 | 538篇 |
出版年
2024年 | 6篇 |
2023年 | 74篇 |
2022年 | 171篇 |
2021年 | 385篇 |
2020年 | 211篇 |
2019年 | 259篇 |
2018年 | 359篇 |
2017年 | 230篇 |
2016年 | 285篇 |
2015年 | 259篇 |
2014年 | 404篇 |
2013年 | 451篇 |
2012年 | 736篇 |
2011年 | 691篇 |
2010年 | 390篇 |
2009年 | 351篇 |
2008年 | 414篇 |
2007年 | 446篇 |
2006年 | 378篇 |
2005年 | 321篇 |
2004年 | 237篇 |
2003年 | 184篇 |
2002年 | 140篇 |
2001年 | 35篇 |
2000年 | 37篇 |
1999年 | 33篇 |
1998年 | 25篇 |
1997年 | 25篇 |
1996年 | 22篇 |
1995年 | 17篇 |
1994年 | 13篇 |
1993年 | 16篇 |
1992年 | 39篇 |
1991年 | 31篇 |
1990年 | 17篇 |
1989年 | 16篇 |
1988年 | 14篇 |
1987年 | 20篇 |
1986年 | 15篇 |
1985年 | 22篇 |
1984年 | 11篇 |
1983年 | 9篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1980年 | 4篇 |
1979年 | 9篇 |
1978年 | 4篇 |
1977年 | 10篇 |
1976年 | 4篇 |
1974年 | 3篇 |
排序方式: 共有7855条查询结果,搜索用时 0 毫秒
11.
Correlation between sperm penetration into the human zona pellucida and in vitro fertilization rates
L. Yogev PhD R. Gamzu R. Hauser A. Botchan A. Amit J. B. Lessing G. Paz and H. Yavetz 《Andrologia》1997,29(2):71-75
Summary. Sperm penetration into the zona pellucida of unfertilized oocytes, and its correlation with in vitro fertilization rates of the sibling oocytes, were assessed. This was performed in order to evaluate the prediction rate of the sperm penetration test into the zona pellucida. Unfertilized oocytes ( n =1872) from 371 cycles were pipetted through a microcapillary, and the remaining sperm cells penetrating the zona pellucida were counted. The mean (±SD) number of spermatozoa that penetrated the zona pellucida of unfertilized oocytes was 12.9±16.37. A significant correlation was found between the fertilization rate and the mean number of spermatozoa that penetrated into the zona pellucida of the unfertilized sibling oocytes (r = 0.48; P < 0.001), or the percent of unpenetrated zonae pellucidae in a cohort (r= —0.43; P < 0.001). However, a distinct variation in the number of spermatozoa that penetrated into the zona pellucida was detected. A step-wise regression analysis proved the number of spermatozoa penetrating the zona pellucida to be more predictive for fertilization rates than the variable of percent of unpenetrated zonae pellucidae. The results imply that although there is interdependence between penetration into the zona pellucida and fertilization rate, the predictive value of sperm penetration test for prognosis and future management after the first in vitro fertilization attempt, is limited. 相似文献
12.
Ana Ortega Ph.D. George Dranitsaris M.Sci.Phm. Jeremy Sturgeon M.D. Heather Sutherland M.Sci. Amit Oza M.D. 《Gynecologic oncology》1997,66(3):454-463
The standard treatment for patients with advanced ovarian cancer (AOC) has been cyclophosphamide and cisplatin (CP). Recently, the results of a large randomized comparative trial demonstrated that the combination of paclitaxel and cisplatin (TP) provided a progression-free survival benefit of 5 months. In this study, a cost–utility analysis was performed from a Canadian health care system perspective to estimate the incremental cost-effectiveness of the TP combination. Twelve AOC patients who received treatment with TP were matched for age and disease stage on a 1-to-2 basis with a CP control. Total hospital resource consumption was then collected for all patients. Treatment preferences were estimated from a cohort of 20 patients and 40 healthy female volunteers using the time trade-off technique. The outcomes were then generated through a decision-analytic model. First-line treatment costs with TP were approximately fourfold greater on a per-cycle basis than the CP alternative (Can$1911 vs Can$459). When progression-free survival benefit and patient treatment preferences were incorporated into the analysis, the results of the decision model revealed an incremental cost between Can$12,000 and Can$24,000 per quality-adjusted progression-free year with the TP protocol. Even though the TP combination has a considerably higher drug acquisition cost, the results of the current analysis suggest that this new chemotherapy regimen does provide patients with substantial quality-adjusted progression-free survival benefit at a reasonable cost to the Canadian health care system. 相似文献
13.
14.
Previous work from this laboratory has already indicated that capsaicin, stabilizes the rat lung membrane lipid system on long-term treatment. This stabilization of the membrane is further supported by our present findings that capsaicin pretreatment causes significant inhibition of various chemically induced lipid peroxidative changes at both cellular and subcellular levels. Both in vivo and in vitro studies, using whole lung and liver tissue slices and mitochondrial and microsomal fractions, have shown that capsaicin pretreatment inhibits peroxidative changes at both cellular and subcellular levels. Both in vivo and in vitro studies, using whole lung and liver tissue slices and mitochondrial and microsomal fractions, have shown that capsaicin pretreatment inhibits peroxidative changes induced by different chemical irritants such as chloroform, dichloromethane, carbon tetrachloride as well as ferrous sulphate. 相似文献
15.
D J Amit 《Proceedings of the National Academy of Sciences of the United States of America》1988,85(7):2141-2145
It is shown that the ideas that led to neural networks capable of recalling associatively and asynchronously temporal sequences of patterns can be extended to produce a neural network that automatically counts the cardinal number in a sequence of identical external stimuli. The network is explicitly constructed, analyzed, and simulated. Such a network may account for the cognitive effect of the automatic counting of chimes to tell the hour. A more general implication is that different electrophysiological responses to identical stimuli, at certain stages of cortical processing, do not necessarily imply synaptic modification, a la Hebb. Such differences may arise from the fact that consecutive identical inputs find the network in different stages of an active temporal sequence of cognitive states. These types of networks are then situated within a program for the study of cognition, which assigns the detection of meaning as the primary role of attractor neural networks rather than computation, in contrast to the parallel distributed processing attitude to the connectionist project. This interpretation is free of homunculus, as well as from the criticism raised against the cognitive model of symbol manipulation. Computation is then identified as the syntax of temporal sequences of quasi-attractors. 相似文献
16.
Studies of bilirubin toxicity at the synaptosome and cellular levels. 总被引:11,自引:0,他引:11
17.
The relationship between blood catalase activity and alcohol consumption was investigated in a group of Caucasian volunteers (N = 191). Subjects individually attended a 1-hr session, during which they were asked to complete the Michigan Alcoholism Screening Test (MAST) and MacAndrew Scale (MAC), supply information on alcohol consumption (averaged over the most recent and typical 30-day periods: Recent and Typical Q-values) and other drug use by answering the Concordia Alcohol Screening Questionnaire (CASQ), and provide a 100-microliter blood sample from the fingertip. Results showed a significant positive relationship between typical Q-Value and catalase activity (r = 0.43, P less than 0.001), which improved after eliminating multiple drug users from the analysis (r = 0.65, P less than 0.001). Multiple regression analyses showed that catalase activity combined with being male, using cocaine or crack, scoring highly on the MAC scale and having alcohol-related problems (MAST), explained a significant portion of the variance in Typical Q-Value. These results support the notion that catalase activity is a strong positive determinant of alcohol intake and support the hypothesis that the enzyme catalase plays a role in regulating voluntary ethanol consumption. 相似文献
18.
19.
20.