全文获取类型
收费全文 | 6786篇 |
免费 | 362篇 |
国内免费 | 67篇 |
专业分类
耳鼻咽喉 | 95篇 |
儿科学 | 164篇 |
妇产科学 | 25篇 |
基础医学 | 711篇 |
口腔科学 | 186篇 |
临床医学 | 460篇 |
内科学 | 1818篇 |
皮肤病学 | 184篇 |
神经病学 | 397篇 |
特种医学 | 269篇 |
外科学 | 1101篇 |
综合类 | 30篇 |
预防医学 | 166篇 |
眼科学 | 253篇 |
药学 | 584篇 |
中国医学 | 8篇 |
肿瘤学 | 764篇 |
出版年
2024年 | 8篇 |
2023年 | 51篇 |
2022年 | 120篇 |
2021年 | 201篇 |
2020年 | 122篇 |
2019年 | 148篇 |
2018年 | 200篇 |
2017年 | 147篇 |
2016年 | 185篇 |
2015年 | 199篇 |
2014年 | 234篇 |
2013年 | 288篇 |
2012年 | 492篇 |
2011年 | 513篇 |
2010年 | 321篇 |
2009年 | 246篇 |
2008年 | 464篇 |
2007年 | 471篇 |
2006年 | 469篇 |
2005年 | 429篇 |
2004年 | 393篇 |
2003年 | 356篇 |
2002年 | 363篇 |
2001年 | 53篇 |
2000年 | 52篇 |
1999年 | 74篇 |
1998年 | 72篇 |
1997年 | 59篇 |
1996年 | 62篇 |
1995年 | 49篇 |
1994年 | 36篇 |
1993年 | 34篇 |
1992年 | 30篇 |
1991年 | 27篇 |
1990年 | 26篇 |
1989年 | 29篇 |
1988年 | 20篇 |
1987年 | 18篇 |
1986年 | 8篇 |
1985年 | 24篇 |
1984年 | 22篇 |
1983年 | 9篇 |
1982年 | 15篇 |
1981年 | 19篇 |
1980年 | 11篇 |
1979年 | 9篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 6篇 |
1974年 | 5篇 |
排序方式: 共有7215条查询结果,搜索用时 15 毫秒
61.
Suzuki H Uchiyama M Tagaya H Ozaki A Kuriyama K Aritake S Shibui K Tan X Kamei Y Kuga R 《Sleep》2004,27(8):1486-1490
STUDY OBJECTIVES: There is a long-standing controversy surrounding the existence of dream experiences during non-rapid eye movement (NREM) sleep. Previous studies have not answered the question whether this "NREM dream" originates from the NREM sleep mechanism because the subject might simply be recalling experiences from the preceding rapid eye movement (REM) sleep. METHODS: We scheduled 11 healthy men to repeat 20-minute nap trials separated by 40-minute periods of enforced wakefulness across a period of 3 days. At the end of the nap trial, each participant answered questions regarding the formal aspects of his dream experiences during the nap trial, using the structured interviews. RESULTS: We obtained a total of 172 dream reports after naps containing REM sleep (REM naps) and 563 after naps consisting of only NREM sleep (NREM naps). Dream reports from NREM naps were less remarkable in quantity, vividness, and emotion than those from REM naps and were obtained more frequently during the morning hours when the occurrences of REM sleep were highest. CONCLUSIONS: These results suggest that the polysomnographic manifestations of REM sleep are not required for dream experiences but that the mechanisms driving REM sleep alter experiences during NREM sleep in the morning. A subcortical activation similar to REM sleep may occur in human NREM sleep during the morning when REM sleep is most likely to occur, resulting in dream experiences during NREM sleep. 相似文献
62.
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
63.
Angiopoietins and angiopoietin-like proteins in angiogenesis. 总被引:7,自引:0,他引:7
Vascular network formation requires several endothelial cell growth factors. These factors have a potent angiogenic effect, and their precise coordination is essential for vascular development. Among them, angiopoietins function through the Tie2 receptor, whose signaling is critical to regulate vascular stabilization and remodeling. It has been reported that the angiopoietin/Tie2 signal is involved in survival and migration of endothelial cells and regulates vascular remodeling and maintenance of vascular integrity. More recent studies demonstrate that angiopoietin/Tie2 signaling is also required for lymphangiogenesis. The authors and several other groups have identified six angiopoietin-like proteins (Angptls) containing a coiled-coil domain and a fibrinogen-like domain, both of which are characteristic of angiopoietins. Interestingly, Angptls also function in angiogenesis through regulating survival and migration of endothelial cells, although Angptls do not bind the angiopoietin receptor Tie2. Currently, Angptls are orphan ligands, but they have been reported to have pleiotropic effects not only on vascular cells but also on metabolism and tumor biology. Here, the authors review current findings relating to the roles of angiopoietins and Angptls in vascular biology and discuss molecular mechanisms relevant to these factors and angiogenesis. 相似文献
64.
Shikata K Kukita Y Matsumoto T Esaki M Yao T Mochizuki Y Hayashi K Iida M 《American journal of medical genetics. Part A》2005,134(3):326-329
We treated a 39-year-old woman with hypoproteinemia and anemia who had profuse gastric polyposis. Radiographic and endoscopic examination showed numerous polyps restricted to the stomach. The patient had pulmonary arteriovenous malformations in the left lung. Histological examination of the resected stomach revealed the gastric polyposis to be composed of cystic dilatation of the glands with small areas of adenocarcinoma. These findings were compatible with gastric juvenile polyposis (GJP) accompanied by gastric cancer. Analysis of genomic DNA revealed that the patient had truncating mutation of SMAD4, a responsible gene for juvenile polyposis (JP). Our case suggests that SMAD4 is possibly a responsible gene for GJP. 相似文献
65.
Wada Y 《Shinrigaku kenkyu : The Japanese journal of psychology》2003,74(5):420-427
Four experiments investigated the effects of cross-modal attention between vision and touch in temporal order judgment tasks combined with spatial cueing paradigm. In Experiment 1, two vibrotactile stimuli with simultaneous or successive onsets were presented bimanually to the left and right index fingers and participants were asked to judge the temporal order of the two stimuli. The tactile stimuli were preceded by a spatially uninformative visual cue. Results indicated that shift of spatial attention yielded by visual cueing resulted in the modulation of accuracy of the subsequent tactile temporal order judgment. However, this cueing effect disappeared when participants judged simultaneity of the two stimuli, instead of their temporal order (Experiment 2) or when the cue lead time between the visual cue and the stimuli was relatively long (Experiment 3). Experiment 4 replicated an effect of crossmodal attention on the direction of visual illusory line motion induced by a somatosensory cue (Shimojo, Miyauchi, & Hikosaka, 1997). These results demonstrate that substantial crossmodal links exist between vision and touch for covert exogenous orienting of attention. 相似文献
66.
67.
Qiang Liu Koichi Ohshirna Yuichi Masuda Masahiro Kikuchi 《Pathology international》1995,45(2):131-136
The Epstein-Barr virus (EBV) has been shown to be associated with numerous human malignancies including Burktt's lymphoma and nasopharyngeal lymphoepithelioma. In addition, some typical gastric adenocarcinomas were also recently reported to demonstrate EBV relevance. The present study was designed to detect EBV in primary gastric lymphoma, using the in situ hybridization (ISH) method, in which oligo-nucleotide probes for the EBERl RNA and the EBV DNA W region have been used. Of the 49 cases of primary gastric lymphoma studied, which all showed B cell immunopheno-type, EBER1 sequences could only be found in four cases, including two low-grade cases and two high-grade cases of histological subtypes while the number of positive cells was less than 50% of the tumor cells. In one case of low-grade mucosa associated lymphoid tissue (MALT) lymphoma, the EBER1 -positive neoplastic cells were found in the regional lymph node, but the primary site of the stomach showed no positive signals. The EBV presence was further confirmed by the EBV DNA ISH. Using the ISH method, rare or occasional positive lymphoid cells (probably non-tumorous bystander cells) could be detected in 10 other cases including all histological subtypes. The present study shows that only a small proportion of primary gastric lymphoma is associated with EBV, and such positive cases could be found in both high- and low-grade histological subtypes. It is also suggested that the EBV presence in the neoplastic cells of some cases of primary gastric lymphoma is most likely a secondary phenomenon. 相似文献
68.
Seiji Miyauchi Yuichi Sugiyama Yasufumi Sawada Kaname Morita Tatsuji Iga Manabu Hanano 《Journal of pharmacokinetics and pharmacodynamics》1987,15(1):25-38
Hepatic elimination of 4-methylumbelliferone (4MU), which has been used as a model compound for conjugative metabolism, was studied by means of a multiple indicator dilution (MID) method in the isolated perfused rat liver. Using this method, three intrinsic hepatic clearances, CL
int,inf
, CL
int,eff, and CL
int,seq, which represent the influx, efflux, and sequestration processes, respectively, were obtained. When the dose was increased from a low dose (50 g/rat liver) to a high dose (3000 g/rat liver), the hepatic availability of 4MU increased from 0.11 to 0.73. With increasing dose, the CL
int,eff value increased approximately two times, while the CL
int,seq value decreased to approximately one-third. The remarkable dose dependence of hepatic availability was due to nonlinearity in both CL
int,eff and CL
int,seq values. However, the CLint,inf
value was almost independent of dose. The dose-dependent change in CLint,seq
might be explained by the saturation of conjugative metabolism of 4-MU, while the increase in the CL
int,eff value with increasing dose might be partly explained by the nonlinear tissue binding of 4-MU, since the tissue unbound fraction determined by an ultrafiltration method using liver homogenate increased approximately 1.5 times at higher concentration of 4-MU compared to that at lower concentrations. In addition, based on a comparison of the individual intrinsic clearances, i.e., CL
int,inf
, CL
int,eff, and CL
int,seq, the major determining process of the apparent hepatic intrinsic clearance of 4MU is thought to be the sequestration process at the high dose. However, at the low dose, the membrane transport process (influx and efflux processes) as well as the sequestration process also determine the apparent hepatic intrinsic clearance. 相似文献
69.
Takayuki ISHIKAWA Kazuhito TAKEUCHI Taiki YAMAMOTO Yuichi NAGATA Atsushi NATSUME 《Neurologia medico-chirurgica》2021,61(2):117
Recently neurosurgical operations have been carried out with water irrigation such as endoscopic third ventriculostomy and tumor resections in ventricles. Water irrigation is one of several published methods that promote hemostasis; however, not enough experimental evidence exists on its efficacy. In this study, we investigate whether hydrostatic pressure and persistent irrigation promote hemostasis in neuroendoscopic surgery. We dissected tails of 12–16-week-old C57BL/6 male mice at 5 mm proximal from the tip and checked for bleeding times under dry and wet conditions at pressures of 0 cmH2O, 10 cmH2O, 15 H2O, and 20 cmH2O without persistent irrigation to bleeding point and 10 cmH2O with persistent irrigation. We then examined the dissected edge with hematoxylin–eosin staining and measured the size of vessels. The average bleeding time of each group is as follows: dry: 203.4 sec, wet: 164.4 sec, 5 cmH2O: 138.6 sec, 10 cmH2O: 104.6 sec (P <0.001), 20 cmH2O: 56 sec (P <0.001), and 10 cmH2O with persistent irrigation: 72.8 sec (P <0.01 compared to 10 cmH2O without persistent irrigation). The maximum caliber of mice’s tail artery was 50–60 μm. Hydrostatic pressure and irrigation are important factors contributing to hemostasis. 相似文献
70.
Noriyuki Amano Kazumasa Matsumoto Yuriko Shimizu Marie Nakamura Hideyasu Tsumura Daisuke Ishii Yuichi Sato Masatsugu Iwamura 《Urologic oncology》2021,39(3):196.e1-196.e7
ObjectiveWe sought to identify heterogeneous nuclear ribonucleoprotein A3 (HNRNPA3) expression in bladder cancer and its relationship to clinicopathological findings and prognosis.MethodsImmunohistochemical staining for HNRNPA3 was performed on 122 archived radical cystectomy specimens, with immunoreactivity being stratified on a 0 to 3 scale. The percentage of HNRNPA3 expressing tumor cells was calculated and multiplied by the staining score over an average of 5 areas to obtain a semiquantitative H-score (maximum value: 300). HNRNPA3 expression was categorized as high (≥80) or low (<80).ResultsThe patients’ median age was 70 years, and the median follow-up period was 39.4 months. High HNRNPA3 expression was significantly associated with lymph node metastasis (P= 0.014) and S100A8, S100A9 and uroplakin III expression (P= 0.028, 0.002, and 0.047, respectively). Log-rank tests indicated that high HNRNPA3 expression was significantly associated with disease progression and cancer-specific death (P= 0.013 and 0.006, respectively). In the Cox proportional hazards regression analysis, only lymph node metastasis was associated with disease progression and cancer-specific survival.ConclusionHNRNPA3 may be a new biomarker to predict biologically aggressive cancers and determine the appropriate treatment modality in patients after radical cystectomy. 相似文献