全文获取类型
收费全文 | 233415篇 |
免费 | 11548篇 |
国内免费 | 393篇 |
专业分类
耳鼻咽喉 | 3051篇 |
儿科学 | 7279篇 |
妇产科学 | 4785篇 |
基础医学 | 33580篇 |
口腔科学 | 5309篇 |
临床医学 | 18464篇 |
内科学 | 51689篇 |
皮肤病学 | 6250篇 |
神经病学 | 20871篇 |
特种医学 | 7004篇 |
外国民族医学 | 101篇 |
外科学 | 28958篇 |
综合类 | 981篇 |
一般理论 | 62篇 |
预防医学 | 21259篇 |
眼科学 | 4556篇 |
药学 | 16458篇 |
中国医学 | 702篇 |
肿瘤学 | 13997篇 |
出版年
2023年 | 1244篇 |
2022年 | 892篇 |
2021年 | 3488篇 |
2020年 | 2071篇 |
2019年 | 3927篇 |
2018年 | 7423篇 |
2017年 | 4876篇 |
2016年 | 4860篇 |
2015年 | 5443篇 |
2014年 | 5692篇 |
2013年 | 9199篇 |
2012年 | 16007篇 |
2011年 | 15950篇 |
2010年 | 7951篇 |
2009年 | 5935篇 |
2008年 | 13707篇 |
2007年 | 14686篇 |
2006年 | 13504篇 |
2005年 | 13364篇 |
2004年 | 12524篇 |
2003年 | 11430篇 |
2002年 | 10826篇 |
2001年 | 6115篇 |
2000年 | 6210篇 |
1999年 | 5525篇 |
1998年 | 896篇 |
1997年 | 742篇 |
1996年 | 719篇 |
1992年 | 3199篇 |
1991年 | 2865篇 |
1990年 | 2734篇 |
1989年 | 2493篇 |
1988年 | 2364篇 |
1987年 | 2193篇 |
1986年 | 2088篇 |
1985年 | 1885篇 |
1984年 | 1397篇 |
1983年 | 1187篇 |
1982年 | 671篇 |
1979年 | 1205篇 |
1978年 | 847篇 |
1977年 | 795篇 |
1975年 | 801篇 |
1974年 | 985篇 |
1973年 | 995篇 |
1972年 | 936篇 |
1971年 | 922篇 |
1970年 | 860篇 |
1969年 | 905篇 |
1968年 | 787篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The genetic basis of the duration and incidence of male wing fanning to pheromone in the pink bollworm moth,Pectinophora gossypiella (Saunders), was examined by artificial selection. Using a still-air bioassay, males from a laboratory colony were selected for increased duration of wing fanning when exposed to a 6535 blend of (Z,E)- and (Z,Z)-7,11-hexadecadienyl acetates. The mean (±SE) duration of wing fanning in the selected line increased from 5.4±1.4 to 17.4±2.7 s after six generations. The increase in wing fanning duration was the result of an increase in response duration among responders and not the percentage of males that responded. Realized heritability of wing-fanning duration was 0.16±0.02. The amount and ratio of pheromone produced by females in the male-selected line did not change.This research was supported in part by NSF Grant PCM-8309398 and a University of Massachusetts Biomedical Research Grant. 相似文献
992.
Mohammad Nasri-Sebdani Flavien Traoré Christian Cognard Daniel Potreau Jean -Pierre Poindessault Guy Raymond 《Pflügers Archiv : European journal of physiology》1990,416(1-2):106-112
The effects of tetracaine (10–50 M) and ryanodine (0.1–10 M) were tested on the slow outward K+ current (I
so) and the mechanical tension of isolated frog muscle fibres in a voltage-clamp device (double mannitol-gap) connected to a mechanoelectric transducer. In the concentration range tested, both drugs induced a simultaneous inhibition of tension and current. In all cases the effect on tension was twice that on current. The tetracaine-induced current and tension blocks were fully reversible and dose-dependent. In contrast the ryanodine effects on current and tension were not reversible and did not exhibit a dose dependence except for the delay before the onset of the response, which was shortened when the concentration was raised. Linear regression analysis of the time-dependent and dose-dependent effects of both drugs indicated a strong correlation between the decreases in tension and current. It is concluded that the slow outward current is partly under the control of the Ca2+ release from sarcoplasmic reticulum during contraction. 相似文献
993.
Comparison of the chelating capacity of EDTA and EGTA, a new demineralized agent, on molars in vitro
Recent morphologic studies have shown qualitative, how demineralizing substances clean teeth roots. In this work we attempt to describe quantitatively the "chelation process" and pH evolution of the quelator solution in-vitro inside the teeth during the reaction. These results indicate that Ca++ coming from hydroxyapatite release protons from EDTAH under neutral conditions. This is the most likely mechanism of the "self-limitation". Furthermore, it allow us to explain why EDTA Im and EGTA Im were more efficient than EDTA Na and EGTA Na upon demineralizing the tooth. EGTA Im turn out to be the fastest demineralizing agent as compared to EDTA Na which is currently employed in endodontic therapy. 相似文献
994.
Summary The purpose of this study was to investigate the relationship between threshold points for heart rate (
) and blood lactate (Th1a) as determined by two objective mathematical models. The models used were the mono-segmental exponential (EXP) model of Hughson et al. and the log-log (LOG) model of Beaver et al. Inter-correlations of these threshold points and correlations with performance were also studied. Seventeen elite runners (mean, SD = 27.5, 6.5 years; 1.73, 0.05 m; 63.8, 7.3 kg; and maximum oxygen consumption of 67.8, 3.7 ml · kg–1 · min–1) performed two maximal multistage running field tests on a 183.9-m indoor track with inclined turns. The initial speed of 9 km · h–1 (2.5 m · s–1) was increased by 0.5 km · h–1 (0.14 m · s–1) every lap for thef
c test and by 1 km · h–1 (0.28 m · s–1) every 4 min for the la test. After fitting the la or thef
c data to the two mathematical models, the threshold speed was assessed in the LOG model from the intersection of the two linear segments (LOG-1a; LOG-f
c) and in the EXP model from a tangent point (TI-1a; TI-f
c). Th1a and
speeds computed with the two models were significantly different (P<0.001) and poorly correlated (LOG-1a vs LOG-f
c:r=0.36, TI-1a vs TI-f
c:r=0.13). In general,
were less well correlated with performance than Th1a. With two different objective mathematical models, this study has shown significant differences and poor correlations between Th1a and
. Thus thef
c inflection point with Conconi's protocol is a poor indicator of the la breakpoint with a conventional multistage protocol and a weaker indicator of running performance. 相似文献
995.
The terms "postmarketing surveillance" or "human phase IV studies" are applied to all those examinations which are performed with a drug following its registration. The principles, methods of these examinations are discussed on the basis of international experiences. The authors also give some examples from Hungarian practice referring to this subject. They consider postmarketing examinations to be as important as the clinical pharmacological examinations preceding the introduction of a drug. The usefulness, role of a drug in the therapy may be definitely determined on the basis of the results of these studies. 相似文献
996.
J D Tissot F Clément J A Schifferli P C Frei D F Hochstrasser P Schneider 《American journal of hematology》1992,40(3):171-175
High-resolution two-dimensional gel electrophoresis (2-DGE) was used to analyse plasma samples and partially purified cold agglutinins (CA) obtained from two selected patients. Both presented an acute hemolytic anemia with CA of high thermal amplitude, normal immunoglobulin levels, no detectable paraproteinemia, and no clinical evidence of a malignant B-cell disorder. The electrophoretograms of their plasma showed evident alternations of the "normal" protein profile, which were directly related to hemolysis (absence of the spots of haptoglobin and in one case of those of hemopexin), but no monoclonal gammopathy. The electrophoretograms of their purified CA revealed two clearly different spot patterns respectively corresponding to a monoclonal IgM and to polyclonal IgM. These results show that the clonality of CA associated with hemolytic anemia can be easily determined by 2-DGE. This technique may be very useful to discriminate chronic cold agglutinin disease in the early phase from "parainfectious" CA. 相似文献
997.
J P Catonné 《Annales médico-psychologiques》1992,150(10):705-719
The Greek physicians of the fourth century B.C. painstakingly described a number of symptoms that they thought were caused by migrations of a restless uterus, said "wandering womb". According to this concept, we can use the term "hysteria", despite the fact that the noun itself never appears in any of the Hippocratic texts. We can determine its origin as being in ancient Egypt from the medical writings of the Egyptian papyri. In the same way, the therapy is mainly of Egyptian origin, using a combination of recipes to make the moving womb return to its proper place in the body cavity. However, we can also identify the rationality of the Greeks, in particular as regards mechanical physiopathology. Hippocratic authors are closely connected with presocratical physics, and manifest a distinct break with magic and religion. Furthermore, they claim that hysteria may result from prolonged sexual continence, an opinion which was to influence medical history for over two thousand years. 相似文献
998.
C Dargent-Paré M De Agostini M Mesbah G Dellatolas 《Cortex; a journal devoted to the study of the nervous system and behavior》1992,28(3):343-351
Age, sex, and handedness effects in foot and eye preferences were studied by questionnaire in large samples of normal adult populations from five different countries (total sample, n = 5064). Foot and eye preference were significantly associated with handedness category (right or left) in all the 10 sex by country samples for foot, and in 9/10 samples for eye. The overall frequencies of crossed preferences were 5% between hand and foot and 19.5% between hand and eye. In right-handers, a gradual shift toward the "right" with increasing age was systematically observed, both for footedness and eyedness. The proportion of crossed hand-foot preference was higher in men than women (7.4% vs 2.5%), and higher in left-handers than right-handers (16.3% vs 4.1%). Sex differences in the proportion of crossed hand-eye preference were variable from one country to the other. 相似文献
999.
We have studied the role of electrical activity in the elimination of axonal targeting errors, which is a normal process in brain development. The experiments were focused on the isthmo-optic nucleus (ION), which, in adults, projects in topographical order on the contralateral retina. During embryogenesis, however, a few isthmo-optic neurons project to the ipsilateral retina, and many project to topographically inappropriate parts of the contralateral one; both kinds of targeting error are known to be eliminated by the deaths of the parent neurons. We injected tetrodotoxin (TTX) intraocularly at embryonic days 13 and 15 and, on the latter, applied a retrograde label to the retina of the same eye. Embryos were fixed at embryonic day 17. In some embryos, the label was a peripherally placed fleck of the carbocyanine dye "diI"; the resulting retrogradely labeled neurons in the contralateral ION were much more widely scattered in the TTX-injected embryos than in controls (errors in topography). In other embryos, the label was a solution of rhodamine-B-isothiocyanate (RITC) injected into the vitreous body; this yielded several ipsilaterally labeled isthmo-optic neurons in the TTX-injected embryos, but virtually none in the controls. The numbers of both kinds of aberrantly projecting neuron approached those previously reported near the beginning of the ION's period of neuronal death. We conclude that electrical activity plays an important role in the elimination of axonal targeting errors in the chick embryo's isthmo-optic system. 相似文献
1000.
J. L. Adrien C. Barthélémy A. Perrot S. Roux P. Lenoir L. Hameury D. Sauvage 《Journal of autism and developmental disorders》1992,22(3):375-394
The Infant Behavioral Summarized Evaluation (IBSE) is a rating scale adapted from the Behavioral Summarized Evaluation (BSE) and specifically related to the assessment of behaviors of young children having autistic disorders. Content validity and reliability studies described in the paper were made from behavior ratings of videotapes for 89 children aged from 6 to 48 months. Results show a significant group of 19 items including some characteristic early autistic behaviors (communicative and social abnormalities) and some that are less commonly described in the syndrome (attentional, perceptive, and adaptive disorders). The value of the use of this scale for clinicians and professionals involved in behavioral evaluations and treatment of young children with developmental disorders and the necessity for further psychometric investigations are discussed.This study was supported by INSERM U.316 Nervous System from the Foetus to the Child. Development, Circulation, Metabolism, L. Pourcelot, INSERM, Network INSERM No. 489001, Grant INSERM No. 911182 (D. Savrage) No. 911008 (L. Hameury) MRT. No. 9906 Fondation Langlois. Gratitude is expressed to Professor G. Lelord who initiated and supervised this study. The authors thank Professor J. Fermanian, Department of Biostatistics, CHU Necker, Paris, for his helpful suggestions and assistance. They also thank Dr. Larmande, Dr. Leddet, Dr. Glorion, and Dr. Garreau for their medical participation in the study and C. Richard, C. Fillatre, J. Rabant, and F. Etourneau for the psychological assessments of children. Special thanks to G. Calzas, M. Barré, A. Lardeux, and D. Lioret for their technical assistance. 相似文献