全文获取类型
收费全文 | 14157篇 |
免费 | 642篇 |
国内免费 | 105篇 |
专业分类
耳鼻咽喉 | 188篇 |
儿科学 | 250篇 |
妇产科学 | 127篇 |
基础医学 | 1519篇 |
口腔科学 | 221篇 |
临床医学 | 764篇 |
内科学 | 3970篇 |
皮肤病学 | 248篇 |
神经病学 | 966篇 |
特种医学 | 475篇 |
外科学 | 2990篇 |
综合类 | 91篇 |
预防医学 | 347篇 |
眼科学 | 269篇 |
药学 | 736篇 |
中国医学 | 40篇 |
肿瘤学 | 1703篇 |
出版年
2023年 | 110篇 |
2022年 | 207篇 |
2021年 | 360篇 |
2020年 | 162篇 |
2019年 | 250篇 |
2018年 | 294篇 |
2017年 | 277篇 |
2016年 | 324篇 |
2015年 | 336篇 |
2014年 | 460篇 |
2013年 | 517篇 |
2012年 | 918篇 |
2011年 | 958篇 |
2010年 | 534篇 |
2009年 | 464篇 |
2008年 | 839篇 |
2007年 | 878篇 |
2006年 | 892篇 |
2005年 | 866篇 |
2004年 | 856篇 |
2003年 | 839篇 |
2002年 | 822篇 |
2001年 | 234篇 |
2000年 | 209篇 |
1999年 | 268篇 |
1998年 | 181篇 |
1997年 | 133篇 |
1996年 | 126篇 |
1995年 | 97篇 |
1994年 | 99篇 |
1993年 | 104篇 |
1992年 | 118篇 |
1991年 | 94篇 |
1990年 | 110篇 |
1989年 | 104篇 |
1988年 | 84篇 |
1987年 | 73篇 |
1986年 | 78篇 |
1985年 | 53篇 |
1984年 | 48篇 |
1983年 | 37篇 |
1982年 | 27篇 |
1981年 | 26篇 |
1979年 | 34篇 |
1977年 | 25篇 |
1973年 | 36篇 |
1970年 | 26篇 |
1969年 | 34篇 |
1968年 | 33篇 |
1967年 | 31篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Yamamoto Y Tanaka H Yamazaki K Shirakawa S 《Shinrigaku kenkyu : The Japanese journal of psychology》2003,74(2):140-147
In this study, we developed a ratings scale for estimating sleep onset that would be capable of providing quantitative evaluations of the quality of the sleep onset process. We also examined factors affecting sleep onset using a questionnaire consisting of two separate clusters of items: the first, consisting of 9 items, related to the quality of sleep onset; and the second, consisting of 56 items, related to factors with apparent effects on sleep onset. The questionnaire was administered to 515 day-workers (range: 25-44 years old) for standardization. Each item was weighted based on the distribution of subject responses to determine discrimination. The reliability coefficient alpha for the questionnaire was high, exceeding 0.8. Of 41 items set out as potential factors affecting sleep onset, the results of the questionnaire indicated that five factors consisting of 26 items could be isolated as most likely affecting sleep onset. Path analysis indicated that sleep onset is more commonly affected by factors present at bedtime than factors related to sleep quality the previous night, or to daytime activities. 相似文献
82.
Blood supply to the retina and the lens in the gerbil (<Emphasis Type="Italic">Meriones unguiculatus</Emphasis>) 总被引:1,自引:0,他引:1
Imada H Isomura G Miyachi E 《Anatomical science international / Japanese Association of Anatomists》2003,78(1):36-41
The blood supply to the retina and the lens in 32 gerbils (Meriones unguiculatus) of both sexes from infancy to maturity was studied under light and stereoscopic microscopes, and a scanning electron microscope.
Mercox (CL-2R; Dai Nippon Ink, Tokyo, Japan) was injected into the left ventricle of 30 animals in order to visualize the
blood supply to the retina and the lens from the ophthalmic artery. The central retinal artery arises from the ophthalmic
artery, passes through the papilla of the optic nerve together with the central retinal vein and penetrates the vitreous space
(cavity of the eye) between the lens and the internal limiting membrane of the retina, where it divides into the central branches
covering the lens and the parietal branches to supply the retina. The former passes through the hyaloid space after branching
several arterioles and then covers the lens like a network from its medial and marginal sides. Different from small experimental
animals, the parietal branches, just after separating from the central one, divides into the nasal, dorsal and temporal branches
in the vitreous space, each of which then subdivides to distribute across the retina on the inner limiting membrane, then
delineates the membrana vasculosa retinae. This basal pattern of vasculization 1 day after birth continues to death. Both
the central and parietal branches of the central retinal artery correspond to the branches of the hyaloid artery in embryo
and the latter is preserved in adult gerbils. 相似文献
83.
Chung-Chuan Chou Shengmei Zhou Hideki Hayashi Motoki Nihei Yen-Bin Liu Ming-Shien Wen San-Jou Yeh Michael C. Fishbein James N. Weiss Shien-Fong Lin Delon Wu Peng-Sheng Chen 《The Journal of physiology》2007,580(3):895-906
We hypothesize that remodelling of action potential and intracellular calcium (Cai ) dynamics in the peri-infarct zone contributes to ventricular arrhythmogenesis in the postmyocardial infarction setting. To test this hypothesis, we performed simultaneous optical mapping of Cai and membrane potential ( V m ) in the left ventricle in 15 rabbit hearts with myocardial infarction for 1 week. Ventricular premature beats frequently originated from the peri-infarct zone, and 37% showed elevation of Cai prior to V m depolarization, suggesting reverse excitation–contraction coupling as their aetiology. During electrically induced ventricular fibrillation, the highest dominant frequency was in the peri-infarct zone in 61 of 70 episodes. The site of highest dominant frequency had steeper action potential duration restitution and was more susceptible to pacing-induced Cai alternans than sites remote from infarct. Wavebreaks during ventricular fibrillation tended to occur at sites of persistently elevated Cai . Infusion of propranolol flattened action potential duration restitution, reduced wavebreaks and converted ventricular fibrillation to ventricular tachycardia. We conclude that in the subacute phase of myocardial infarction, the peri-infarct zone exhibits regions with steep action potential duration restitution slope and unstable Cai dynamics. These changes may promote ventricular extrasystoles and increase the incidence of wavebreaks during ventricular fibrillation. Whereas increased tissue heterogeneity after subacute myocardial infarction creates a highly arrhythmogenic substrate, dynamic action potential and Cai cycling remodelling also contribute to the initiation and maintenance of ventricular fibrillation in this setting. 相似文献
84.
Hozumi Katsuto; Kondo Motonari; Nozaki Hideki; Kobori Akiko; Nishimura Takashi; Nishikawa Shin-Ichi; Sugamura Kazuo; Habu Sonoko 《International immunology》1994,6(9):1451-1454
The effects of IL-7 on the growth and differentiation of thymocyteswere analyzed using murine fetal thymua organ cultures (FTOC)in the presence of mAbs specific for the conventional IL-7 receptor(1L-7R) and for the common (c) chain. In FTOC, the developmentof CD4–CD8– double-negative thymocytes to CD4+CD8+double-positive (DP) and CD4+ or CD8+ single-positive (SP) cellswas not completely blocked by adding these mAbs, although cellgrowth was reduced by the treatment. To define a developingstage sensitive to the mAbs, most immature thymocytes, Pgp-1+c-kit cells, were cultured in the 2-deoxyguartosine treatedfetal thymus. In the presence of both mAbs in the culture, neitherDP nor SP thymocytes developed whereas either of the mAbs partiallyblocked their development. These results indicate that the Cchain is involved in early T cell development as an indispensablesubunlt of the functional IL-7 receptor complex. 相似文献
85.
Methyl-3,3,3-trifluoropropylsiloxane (F)-dimethylsiloxane (D) random and block copolymers were prepared. The random copolymers were prepared by equilibrium copolymerization starting from a mixture of cyclic F and D siloxanes with potassium silanolate as the catalyst. The F-D block copolymer was prepared by sequential anionic living polymerization of strained cyclic trisiloxanes using butyllithium as initiator, first polymerizing D3 then adding F3 after consumption of D3. The copolymer microstructure was established by means of 29Si NMR, differential scanning calorimetry (DSC), and gel-permeation chromatography (GPC). Characteristic glass transition temperature (Tg) shifts were observed depending on the F:D ratio of the random copolymers. It was demonstrated that the tensile strength of the poly(methyl-3,3,3-trifluoropropylsiloxane)-poly(dimethylsiloxane) (PTFPMS-PDMS) blend system was improved when either of the copolymers was added. 相似文献
86.
87.
Akiyoshi Nishikawa Takuji Tanaka Nobuyuki Kanai Kazuo Kato Hideki Mori Masayoshi Takahashi 《Pathology international》1987,37(7):1003-1007
Exfoliative cytopathology of alveolar rhabdomyosarcoma is presented. A 34-year-old male was found to have alveolar rhabdomyosarcoma of the retroperitoneum at autopsy. Ascites was recognized in the course of this disease. Cytological features in the ascites were characterized by relatively small-sized ovoid cells observed singly or in loose clusters. The neoplastic cells possessed small amount of rather vesicular cytoplasm and an eccentric nucleus. The nucleus characteristically revealed multiple deep indentations in the nuclear membrane, a few prominent eosinophilic nucleoli and finely granular or evenly distributed chromatin pattern. These cytological findings, especially the nuclear features, might be useful to differentiate alveolar rhabdomyosarcoma from other neoplasms which consist of relatively small-sized ovoid cells even if the striated muscle origin cannot be confirmed by immunoperoxidase staining. 相似文献
88.
Methods for culture ofBombyx mori wing discs 总被引:1,自引:0,他引:1
Hideki Kawasaki 《Methods in Cell Science》1989,12(1):31-33
Summary A culture method forBombyx wing discs is described. Grace's insect medium,Bombyx hemolymph, and moderate doses of ecdysterone (0.02 to 0.1 µg/ml) were necessary for complete imaginal differentiation ofBombyx wing discs. This procedure is useful for understanding ecdysteroid action on insect imaginal differentiation and metamorphosis. 相似文献
89.
S. Oh-ishi Takako Kizaki Tomomi Ookawara Koji Toshinai Shukoh Haga Fujio Karasawa Tetsuo Satoh Naokazu Nagata L. L. Ji Hideki Ohno 《Pflügers Archiv : European journal of physiology》1998,435(6):767-774
The aim of the current study was to elucidate the synergism of dietary calcium restriction and exhaustive exercise in the
antioxidant enzyme system of rat soleus muscle, and to investigate the involvement of neutrophils in exercise-induced muscle
damage. Forty-eight male Wistar rats were assigned to the following groups: control (C) or calcium-restricted [1 month (1 M)
or 3 months (3 M)]. Each group was subdivided into acutely exercised or non-exercised groups. Soleus muscle from each rat
was analysed to determine the levels of antioxidant enzymes [Mn-superoxide dismutase (SOD), Cu,Zn-SOD, glutathione peroxidase
(GPX), and catalase (CAT)]. Dietary calcium restriction resulted in calcium deficiency and upregulated the antioxidant enzymes
examined except GPX. Conversely, exhaustive exercise significantly decreased GPX and CAT, but not SODs activities in the calcium-restricted
(1 M and/or 3 M) rats. Contents of immunoreactive Mn-SOD and Cu,Zn-SOD were only increased in the 3 M rats. During calcium
restriction, the mRNA expression of both forms of SOD showed initial upregulation, followed by downregulation. Exhaustive
exercise significantly increased the mRNA expressions only in the 3 M rats. Moreover, exhaustive exercise markedly increased
myeloperoxidase activity in soleus muscles from the 1 M and 3 M rats compared with the C rats, and significantly enhanced
the ability of neutrophils to generate superoxide in the 3 M rats. The results demonstrate that dietary calcium restriction
upregulates certain antioxidant enzyme activities in rat soleus muscle, indicating an enhanced resistance to potential increases
in intracellular reactive oxygen species. The results also suggest that exhaustive exercise may cause oxidative damage in
soleus muscle of calcium-deficient rats through the activation of neutrophils.
Received: 4 August 1997 / Received after revision: 29 September 1997 / Accepted: 26 November 1997 相似文献
90.
In the encéphale isolé cat preparation the surface of precruciate cortex was electrically stimulated. Intracellular responses underneath the stimulated site were recorded to assess the vertical spread of activities across the cortical layers. To the epicortical stimulation (EPICS) with intensity adjusted to evoke a pure negative wave in the direct cortical response (DCR), only some neurons in relatively superficial layers responded with excitatory postsynaptic potentials (EPSPs). Stimuli intensified to evoke both the negative and subsequent positive waves in DCR produced in all tested cells either EPSPs, inhibitory postsynaptic potentials (IPSPs), or both. Direct or axonal antidromic excitation of the cell was observed only infrequently. Cells with EPSPs distributed through all the layers with two peak populations in laminae II and V-VI. Those with IPSPs were located mainly in the upper half of lamina III with a few in more superficial as well as in deeper layers. Both EPSPs and IPSPs showed mono- or oligosynaptic latencies (0.6-10 msec) that tended to become longer in deep than in superficial layers. Some deep layer cells including fast and slow pyramidal tract cells showed slowly rising monosynaptic EPSPs of dendritic origin. Further late responses consisted of EPSPs, IPSPs, disfacilitation (DF), and disinhibition (DI). DF or DI occurred in some deep layer cells. Two modes of vertical spread of activities were postulated: one the cascade transmissions which increased response repertoire toward the depths, and the other the electrotonic spread of EPSPs along dendrites. 相似文献