全文获取类型
收费全文 | 1210篇 |
免费 | 91篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 31篇 |
妇产科学 | 19篇 |
基础医学 | 96篇 |
口腔科学 | 6篇 |
临床医学 | 110篇 |
内科学 | 286篇 |
皮肤病学 | 49篇 |
神经病学 | 77篇 |
特种医学 | 28篇 |
外科学 | 192篇 |
综合类 | 86篇 |
一般理论 | 1篇 |
预防医学 | 58篇 |
眼科学 | 25篇 |
药学 | 133篇 |
中国医学 | 16篇 |
肿瘤学 | 88篇 |
出版年
2023年 | 10篇 |
2022年 | 24篇 |
2021年 | 47篇 |
2020年 | 26篇 |
2019年 | 41篇 |
2018年 | 53篇 |
2017年 | 40篇 |
2016年 | 50篇 |
2015年 | 40篇 |
2014年 | 57篇 |
2013年 | 61篇 |
2012年 | 85篇 |
2011年 | 65篇 |
2010年 | 37篇 |
2009年 | 48篇 |
2008年 | 59篇 |
2007年 | 46篇 |
2006年 | 61篇 |
2005年 | 39篇 |
2004年 | 29篇 |
2003年 | 30篇 |
2002年 | 35篇 |
2001年 | 22篇 |
2000年 | 14篇 |
1999年 | 25篇 |
1998年 | 18篇 |
1997年 | 17篇 |
1996年 | 21篇 |
1995年 | 29篇 |
1994年 | 14篇 |
1993年 | 12篇 |
1992年 | 12篇 |
1991年 | 7篇 |
1990年 | 10篇 |
1989年 | 7篇 |
1988年 | 10篇 |
1987年 | 13篇 |
1986年 | 11篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1983年 | 9篇 |
1982年 | 9篇 |
1981年 | 3篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1975年 | 5篇 |
1958年 | 3篇 |
1957年 | 4篇 |
1956年 | 3篇 |
1955年 | 3篇 |
排序方式: 共有1305条查询结果,搜索用时 12 毫秒
1.
Pankaj Dabir Snehal Dabir B V Siva Prasad M V R Reddy 《Infection, genetics and evolution》2006,6(4):287-291
Molecular characterization of Wuchereria bancrofti is essential to develop suitable anti-filarial drugs and vaccines. We describe here isolation, sequence analysis and cloning of a partial cDNA of an enzyme superoxide dismutase from this parasite. The immunoscreening of a lambda zap W. bancrofti microfilarial (Mf) cDNA library with microfilaremic sera had resulted in the isolation of several seroreactive clones including, WbSOD. This clone contained a 309 bp insert and showed significant nucleotide and deduced amino acid sequence homologies to the superoxide dismutases of other nematode parasites. The antioxidant property of this enzyme may have important contribution in the defense mechanism of the parasite against host immune response. 相似文献
2.
3.
Zongli Lin Meir Pachter Siva Banda Yacov Shamash 《Optimal control applications & methods.》2002,23(1):21-43
A design technique (Control of Uncertain Systems with Bounded Inputs, Tarbouriech S, Garcia G, (Eds), Lecture Notes in Control and Information Sciences, vol. 227 , Springer: Berlin, 1997; 173–186) recently proposed for stabilization of a linear system with rate‐limited actuators is utilized to design feedback laws that cause the system output to track a desired command signal. This design technique combines two design techniques recently developed for linear systems with position limited actuators, piecewise‐linear LQ control (Automatica, 1994; 30 : 403–416) and low‐and‐high gain feedback (IEEE Trans. Automat. Control, 1996; 41 : 368–378), and hence takes advantage of both design techniques, while avoiding their disadvantages. In the case that only the output is available for feedback, the performance of the state feedback law is preserved by the use of a fast observer. An open‐loop exponentially unstable fighter aircraft is used to demonstrate the effectiveness of the proposed control design method. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
4.
Introduction and Aims. Different self‐report methods tend to produce different estimates of alcohol consumption. The present study compares differences in rates and risk levels based on responses to a modified version of the Daily Drinking Questionnaire (m‐DDQ) and quantity‐frequency (QF) questions. Design and Methods. The sample comprised 2082 university students, 61% of whom were female and 39% male with a mean age of 23.5 years. An email containing an online link to a brief six‐question survey was emailed to students enrolled in participating faculties at the University of Wollongong, Australia. Current drinkers completed m‐DDQ and QF questions about alcohol consumption. Results. QF methods identified significantly lower estimates of consumption (Mean = 9.15, SD = 12.51) compared with m‐DDQ (Mean = 13.06, SD = 14.07). Allocation to risk categories based on the Australian Alcohol Guidelines were conducted for both the m‐DDQ and QF methods. Almost twice as many students were found to be drinking at levels considered risky using the m‐DDQ method compared with QF. In addition, the relative rank order of participants varied significantly between the two methods. Discussion and Conclusions. The m‐DDQ method identified higher rates of drinking and categorised almost twice as many individuals into risky categories of drinking compared with QF. Such variations have major implications for identification of risk groups in health promotion or prevention programs.[Utpala‐Kumar R, Deane FP. Rates of alcohol consumption and risk status among Australian university students vary by assessment questions. Drug Alcohol Rev 2009] 相似文献
5.
6.
Andrew G. Sparks Hsi-Han Yeh Siva S. Banda 《Optimal control applications & methods.》1990,11(4):307-325
This paper introduces a design methodology for a dynamic compensator that simultaneously minimizes the upper bound of a quadratic performance index and the H∞-norm of a disturbance transfer function matrix of a multiple-input/multiple-output system whose model contains parameter uncertainty in the state and input matrices. The real parameter uncertainty is modelled as additional measurement outputs and as additional weights on the existing noise inputs and measurement outputs of the system. The compensator equations are derived by taking the dual of a system with parameter variation in the state and output matrices, for which the compensator equations have previously been derived, and then taking the dual of the compensator equations. An algorithm for applying this theory is given and an example is shown. 相似文献
7.
8.
9.
Circulating filarial antigen in cats infected with Brugia pahangi is indicative of the presence of adult worms 总被引:1,自引:1,他引:0
H. KUMAR C. BALDWIN D.W. BIRCH D.A. DENHAM F. DE MEDEIROS I.T.C. MIDWINTER A. SMAIL 《Parasite immunology》1991,13(4):405-412
Using counterimmunoelectrophoresis with rabbit antisera raised against soluble extracts of adult females of Brugia pahangi parasite antigen was detected in the serum of all cats repeatedly infected with B. pahangi. Antigen was never detected in uninfected cats. The antigen was associated with the presence of adult worms. Antigen was detected consistently in a cat that was amicrofilaraemic but at autopsy harboured only two or three adult worms. Conversely, some cats showed slowly declining numbers of microfilariae and, in these, circulating antigen declined before the number of microfilariae. Eventually no antigen was detectable in circulation whereas microfilariae, although in diminishing numbers, were still present. At autopsy no adult worms were found in these cats. Antigen also appeared in several cats before they became microfilaraemic. 相似文献
10.
Benign positional vertigo is a potentially disabling condition characterized by episodic vertigo following certain provocative head movements. In most patients it is self limiting; however, in a few it may prove intractable, causing considerable social morbidity. In these patients surgery may be considered. Surgery previously involved section of the vestibular or singular nerves, involving a significant risk to hearing and to the facial nerve. Ablation of the labyrinth may even be considered. The new surgical technique of occlusion of the posterior semicircular canal has proved to be curative in most patients with benign positional vertigo with little risk to hearing. This paper describes our experience of fenestration and occlusion of the posterior semicircular canal in four patients. 相似文献