全文获取类型
收费全文 | 9867篇 |
免费 | 435篇 |
国内免费 | 58篇 |
专业分类
耳鼻咽喉 | 88篇 |
儿科学 | 176篇 |
妇产科学 | 144篇 |
基础医学 | 1156篇 |
口腔科学 | 284篇 |
临床医学 | 656篇 |
内科学 | 2199篇 |
皮肤病学 | 155篇 |
神经病学 | 767篇 |
特种医学 | 555篇 |
外科学 | 2049篇 |
综合类 | 31篇 |
一般理论 | 1篇 |
预防医学 | 209篇 |
眼科学 | 84篇 |
药学 | 644篇 |
中国医学 | 16篇 |
肿瘤学 | 1146篇 |
出版年
2023年 | 55篇 |
2022年 | 98篇 |
2021年 | 173篇 |
2020年 | 91篇 |
2019年 | 149篇 |
2018年 | 151篇 |
2017年 | 158篇 |
2016年 | 163篇 |
2015年 | 187篇 |
2014年 | 223篇 |
2013年 | 255篇 |
2012年 | 467篇 |
2011年 | 513篇 |
2010年 | 293篇 |
2009年 | 242篇 |
2008年 | 440篇 |
2007年 | 482篇 |
2006年 | 477篇 |
2005年 | 506篇 |
2004年 | 462篇 |
2003年 | 449篇 |
2002年 | 464篇 |
2001年 | 342篇 |
2000年 | 323篇 |
1999年 | 332篇 |
1998年 | 157篇 |
1997年 | 114篇 |
1996年 | 124篇 |
1995年 | 75篇 |
1994年 | 88篇 |
1993年 | 66篇 |
1992年 | 220篇 |
1991年 | 193篇 |
1990年 | 173篇 |
1989年 | 157篇 |
1988年 | 184篇 |
1987年 | 153篇 |
1986年 | 121篇 |
1985年 | 137篇 |
1984年 | 94篇 |
1983年 | 86篇 |
1979年 | 71篇 |
1978年 | 58篇 |
1977年 | 45篇 |
1976年 | 42篇 |
1974年 | 43篇 |
1973年 | 44篇 |
1972年 | 51篇 |
1971年 | 42篇 |
1969年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
N-Acrylyl-2-oxazolidone was synthesized by the reaction of N-sodium-2-oxazolidone with acrylyl chloride. N-Acrylyl-2-oxazolidone (M1) was polymerized and copolymerized with styrene (M2) by free radical initiator. The monomer reactivity ratios, r1 (= 0.24) and r2 (= 1.35) were determined by the method of FINEMAN and ROSS, and the ALFREY-PRICE Q (= 0.37) and e (= 0.367) values were estimated. These polymers were soluble in dimethylformamide and dimethylsulfoxide, but insoluble in common organic solvents. They formed complexes with phenol, halogens and methyl bromide. Further, the bonding characters in the complexes of various polymers containing 2-oxazolidone moiety and phenols, methyl bromide and halogens were investigated. 相似文献
72.
Mori S Endo M Nishizawa K Ohno M Miyazaki H Tsujita K Saito Y 《Physics in medicine and biology》2005,50(22):N359-N370
The prototype cone-beam CT (CBCT) has a larger beam width than the conventional multi-detector row CT (MDCT). This causes a non-uniform angular distribution of the x-ray beam intensity known as the heel effect. Scan conditions for CBCT tube current are adjusted on the anode side to obtain an acceptable clinical image quality. However, as the dose is greater on the cathode side than on the anode side, the signal-to-noise ratio on the cathode side is excessively high, resulting in an unnecessary dose amount. To compensate for the heel effect, we developed a heel effect compensation (HEC) filter. The HEC filter rendered the dose distribution uniform and reduced the dose by an average of 25% for free air and by 20% for CTDI phantoms compared to doses with the conventional filter. In addition, its effect in rendering the effective energy uniform resulted in an improvement in image quality. This new HEC filter may be useful in cone-beam CT studies. 相似文献
73.
Hideki Endo Takahiro Yonezawa Felix Rakotondraparany Motoki Sasaki Masami Hasegawa 《Annals of anatomy》2006,188(4):383-390
The hindlimb muscles in four species of Tenrecidae (Oryzoryctinae: Talazac long-tailed tenrec and web-footed tenrec, Tenrecinae: lesser hedgehog tenrec, and streaked tenrec), were examined macroscopically. The weight ratios of the muscles to the body in the oryzoryctinid species are larger than those in Tenrecinae, since the Oryzoryctinae species have an obviously smaller body from the evolutionary point of view. It can be primarily pointed out that the adaptation of the body size is different between the two subfamilies, and secondarily, that functional adaptation to locomotion is complete within each subfamily. The weight data and the morphological findings demonstrate that the web-footed tenrec possesses an extraordinary large M. semimembranosus in comparison to the Talazac long-tailed tenrec in their weight ratios. This muscle may act as a strong flexor motor in the knee joint during the aquatic locomotion of the web-footed tenrec. Since the other muscles of the web-footed tenrec are similar to those of the Talazac long-tailed tenrec regards weight ratio data, we think that the web-footed tenrec may have derived from a terrestrial ancestor such as the long-tailed tenrecs. In Tenrecinae the streaked tenrec is equipped with larger Mm. adductores, M. semimembranosus and M. triceps surae than the lesser hedgehog tenrec. This species is adapted to fossorial life derived from non-specialized ancestors within the evolutionary lines of the spiny tenrecs. 相似文献
74.
Yamaguchi U Hasegawa T Morimoto Y Tateishi U Endo M Nakatani F Kawai A Chuman H Beppu Y Endo M Kurotaki H Furuta K 《Journal of clinical pathology》2005,58(10):1051-1056
BACKGROUND: Over 90% of Ewing's sarcoma/primitive neuroectodermal tumour (ES/PNET) cases have the t(11;22) chromosomal rearrangement, which is also found in other small round cell tumours, including desmoplastic small round cell tumour (DSRCT) and clear cell sarcoma (CCS). Although this rearrangement can be analysed by fluorescence in situ hybridisation (FISH) using routinely formalin fixed, paraffin wax embedded (FFPE) tissues when fresh or frozen tissues are not available, a sensitive and convenient detection method is needed for routine clinical diagnosis. AIMS: To investigate the usefulness of newly developed probes for detecting EWS rearrangement resulting from chromosomal translocations using FISH and FFPE tissue in the clinical diagnosis of ES/PNET, DSRCT, and CCS. METHODS: Sixteen ES/PNETs, six DSRCTs, and six CCSs were studied. Three poorly differentiated synovial sarcomas, three alveolar rhabdomyosarcomas, and three neuroblastomas served as negative controls. Interphase FISH analysis was performed on FFPE tissue sections with a commercially available EWSR1 (22q12) dual colour, breakapart rearrangement probe. RESULTS: One fused signal and one split signal of orange and green, demonstrating rearrangement of the EWS gene, was detected in 14 of 16 ES/PNETs, all six DRSCTs, and five of six CCSs, but not in the negative controls. CONCLUSIONS: Interphase FISH using this newly developed probe is sensitive and specific for detecting the EWS gene on FFPE tissues and is of value in the routine clinical diagnosis of ES/PNET, DSRCT, and CCS. 相似文献
75.
This study investigated the effects of anger evoked by earlier provocation on cognition, emotion, and aggressive behavior after being exposed to media violence. Sixty male undergraduates participated in the experiment. Before viewing one of three videos (either highly violent, violent with high entertainment, or nonviolent), half of the subjects were provoked by a confederate posing as another subject. Subjects' heart rates and eyeblink rates were recorded while viewing the video. After viewing the video, subjects described their thoughts that occurred while watching the video and rated their affective reactions toward the video. Finally, subjects' aggressive behavior toward the confederate was measured. Results of covariance structure analysis suggested that (a) anger evoked by provocation and high level of violence in videos additively elicited negative cognition and affect, which further facilitated aggressive behavior, and (b) high level of entertainment in videos elicited positive cognition and affect, which alleviated negative cognition and affect. 相似文献
76.
We determined whether feeding with powdered diet improved the visuospatial ability in female rats by checking the expression of N-methyl-D-aspartate receptor (NMDAR) subunit 1 (NR1) mRNA in the hippocampus. In rats fed standard pelleted diet, males performed better than females in a radial 8-arm maze task as we reported previously. We found that the expression of NR1 mRNA, which may be the key mediator in visuospatial ability in the hippocampus, was also higher in males than in females. However, in rats fed powdered diet, no sex difference was seen in the radial 8-arm maze task and the expression of NR1 mRNA in the hippocampus, since feeding with powdered diet improved the visuospatial ability with increases in the expression of NR1 mRNA in the hippocampus in females. We suggest that the sex difference in visuospatial ability is at least in part due to feeding conditions. 相似文献
77.
Summary: Innate immunity was formerly thought to be a non‐specific immune response characterized by phagocytosis. However, innate immunity has considerable specificity and is capable of discriminating between pathogens and self. Recognition of pathogens is mediated by a set of pattern recognition receptors, which recognize conserved pathogen‐associated molecular patterns (PAMPs) shared by broad classes of microorganisms, thereby successfully defending invertebrates and vertebrates against infection. Lectins, carbohydrate‐binding proteins, play an important role in innate immunity by recognizing a wide range of pathogens. Mannose‐binding lectin (MBL) and ficolin are lectins composed of a lectin domain attached to collagenous region. However, they use a different lectin domain: a carbohydrate recognition domain (CRD) is responsible for MBL and a fibrinogen‐like domain for ficolin. These two collagenous lectins are pattern recognition receptors, and upon recognition of the infectious agent, they trigger the activation of the lectin‐complement pathway through attached serine proteases, MBL‐associated serine proteases (MASPs). A similar lectin‐based complement system, consisting of the lectin–protease complex and C3, is present in ascidians, our closest invertebrate relatives, and functions in an opsonic manner. We isolated several lectins homologous to MBLs and ficolins and several MASPs in invertebrates and lower vertebrates, and herein we discuss the molecular evolution of these molecules. Based on these findings, it seems likely that the complement system played a pivotal role in innate immunity before the evolution of an acquired immune system in jawed vertebrates. 相似文献
78.
Nerve growth factor is present in skin in limiting amounts and is known to regulate the plasticity and the sensitivity of nociceptive neurons. Recently, knock-out mouse studies showed that neurotrophin-3 and brain-derived neurotrophic factor are required for the postnatal survival and functional maturation, respectively, of tactile sensory neurons. However, the roles of neurotrophin-3 and brain-derived neurotrophic factor in adult sensory neurons have not been clarified. Here, we report an unexpected and marked acute loss of tactile sense in the rat hind paw after adjuvant-induced inflammation. This loss was shown to be closely correlated with decreases in the expression of brain-derived neurotrophic factor, and to a lesser extent of neurotrophin-3 in the inflamed skin. Administration of brain-derived neurotrophic factor, but not neurotrophin-3, after inflammation accelerated the recovery of tactile sense.These results suggested a role of brain-derived neurotrophic factor in the physiological regulation of tactile sense in adulthood. 相似文献
79.
80.
ICR mice were treated with a carcinogen, N-butyl-N'-butanolnitrosoamine BBN), every day for 8 consecutive weeks and the effects of oral administration of edible mushrooms on the induction of urinary bladder carcinoma and on the activities of macrophages and lymphocytes were studied. Bladder carcinoma were found in all 10 mice (100%) treated with BBN alone, while we observed carcinoma only in 9 of 17 mice (52.9%), in 7 of 15 mice (46.7%) and 13 of 20 mice (65.0%) treated with Lentinus edodes, Grifola frondosa and Pleurotus ostreatus, respectively. Chemotactic activity of macrophages was suppressed in mice treated with BBN alone but maintained almost the normal level in mice treated with BBN plus Lentinus, Grifola or Pleurotus. Lymphocytes collected from mice treated with BBN plus each mushroom showed almost normal blastogenic response against concanavalin A, although those from mice treated with BBN alone completely retarded their response. Cytotoxic activity of lymphocytes against Yac-1 cells was also maintained at a normal level in mice treated with BBN plus each mushroom. Whereas in mice treated with BBN alone significant depression of NK cell activity occurred. Significantly higher cytotoxic activity against P-815 cells was observed in lymphocytes from mice treated with BBN plus each mushroom than that in lymphocytes from normal mice or mice treated with BBN alone. 相似文献