全文获取类型
收费全文 | 8991篇 |
免费 | 446篇 |
国内免费 | 88篇 |
专业分类
耳鼻咽喉 | 80篇 |
儿科学 | 160篇 |
妇产科学 | 81篇 |
基础医学 | 1009篇 |
口腔科学 | 124篇 |
临床医学 | 466篇 |
内科学 | 2666篇 |
皮肤病学 | 144篇 |
神经病学 | 656篇 |
特种医学 | 366篇 |
外科学 | 1648篇 |
综合类 | 41篇 |
预防医学 | 201篇 |
眼科学 | 156篇 |
药学 | 548篇 |
中国医学 | 11篇 |
肿瘤学 | 1168篇 |
出版年
2024年 | 12篇 |
2023年 | 61篇 |
2022年 | 34篇 |
2021年 | 254篇 |
2020年 | 131篇 |
2019年 | 173篇 |
2018年 | 216篇 |
2017年 | 184篇 |
2016年 | 231篇 |
2015年 | 252篇 |
2014年 | 309篇 |
2013年 | 365篇 |
2012年 | 603篇 |
2011年 | 631篇 |
2010年 | 344篇 |
2009年 | 359篇 |
2008年 | 621篇 |
2007年 | 661篇 |
2006年 | 641篇 |
2005年 | 632篇 |
2004年 | 604篇 |
2003年 | 575篇 |
2002年 | 563篇 |
2001年 | 87篇 |
2000年 | 72篇 |
1999年 | 93篇 |
1998年 | 134篇 |
1997年 | 94篇 |
1996年 | 78篇 |
1995年 | 83篇 |
1994年 | 69篇 |
1993年 | 43篇 |
1992年 | 48篇 |
1991年 | 40篇 |
1990年 | 32篇 |
1989年 | 25篇 |
1988年 | 20篇 |
1987年 | 20篇 |
1986年 | 12篇 |
1985年 | 11篇 |
1984年 | 11篇 |
1983年 | 14篇 |
1982年 | 17篇 |
1981年 | 9篇 |
1980年 | 7篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1974年 | 4篇 |
1973年 | 4篇 |
1966年 | 4篇 |
排序方式: 共有9525条查询结果,搜索用时 19 毫秒
101.
102.
103.
Wnt signaling plays an essential role in neuronal specification of the dorsal spinal cord 总被引:14,自引:0,他引:14
In the developing spinal cord, signals from the roof plate are required for the development of three classes of dorsal interneuron: D1, D2, and D3, listed from dorsal to ventral. Here, we demonstrate that absence of Wnt1 and Wnt3a, normally expressed in the roof plate, leads to diminished development of D1 and D2 neurons and a compensatory increase in D3 neuron populations. This occurs without significantly altered expression of BMP and related genes in the roof plate. Moreover, Wnt3a protein induces expression of D1 and D2 markers in the isolated medial region of the chick neural plate, and Noggin does not interfere with this induction. Thus, Wnt signaling plays a critical role in the specification of cell types for dorsal interneurons. 相似文献
104.
Yuichiro Hirata Shun Iida Takeshi Arashiro Sayaka Nagasawa Hisako Saitoh Hiroyuki Abe Masako Ikemura Yohsuke Makino Rintaro Sawa Hirotaro Iwase Tetsuo Ushiku Tadaki Suzuki Shinji Akitomi 《Pathology international》2023,73(3):120-126
During the coronavirus disease 2019 (COVID-19) pandemic, autopsies have provided valuable insights into the pathogenesis of COVID-19. The precise effect of this pandemic on autopsy procedures in Japan, especially in instances unrelated to COVID-19, has not yet been established. Therefore, we conducted a questionnaire survey from December 2020 to January 2021 regarding the status of pathological autopsy practices in Japan during the first year of the COVID-19 pandemic. The questionnaire was sent to 678 medical facilities with pathologists, of which 227 responded. In cases where a confirmed diagnosis of COVID-19 was not made at the time of autopsy, many facilities counted them as suspected COVID-19 cases if pneumonia was suspected clinically. At around half of the sites, autopsies were prohibited for suspected COVID-19 cases. In addition, the number of autopsies of non-COVID-19 cases during the pandemic period was also investigated, and a significant decrease was observed compared with the incidence in the pre-pandemic period. The COVID-19 pandemic has affected not only the autopsies of COVID-19 cases but also the entire practice of pathological autopsies. It is necessary to establish a system that supports the implementation of pathological autopsy practices during the pandemic of an emerging infectious disease. 相似文献
105.
Tomita M Ayabe H Tagawa Y Hara S Tsuji H Oka T Akamine S Takahashi T Shingu H 《Breast cancer (Tokyo, Japan)》1995,2(2):113-117
The procedure of aspiration biopsy cytology by fine needle aspiration (ABC) is as option in establishing definitive diagnoses for breast cancers. In this series, a needle size of 21G was considered most suitable for ABC as well as flow cytometric DNA analysis. Histograms from fresh samples aspirated by fine needle clearly delineated a sharp peak in G&sup0;G(1) phases and also a better CV was obtained than with paraffin-embedded preparations. In addition, fresh samples gave more reliable DI and suggested the value of measuring nuclear DNA contents. It is believed that the prognoses of breast cancers are closely associated with DNA ploidy patterns. In this sense, flow cytometric DNA analysis of fresh samples of ABC is regarded as important in clinical use. 相似文献
106.
Tetsuo Hadama Yoshiaki Mori Osamu Shigemitsu Tatsunori Kimura Shinji Miyamoto Hidenori Sako Tooru Soeda Toshihide Yoshimatsu Yuzo Uchida 《Surgery today》1996,26(1):60-63
We report herein the rare case of a 79-year-old man who suffered permanent paraplegia after undergoing an otherwise successful total arch replacement for a ruptured aortic arch aneurysm. During cardiopulmonary bypass, perfusion to the distal aorta was maintained from the femoral artery, and postoperative aortography showed intact tributaries from the aorta including the intercostal arteries. Postoperative paraplegia is an extremely rare complication of operations on the aortic arch; however, we speculate that the paraplegia in this patient could be attributed either to a steal phenomenon involving the radicular artery, or to the anatomical particularity of the spinal cord artery described by Cole and Gutelius as the segmental system. 相似文献
107.
Degradation of methyl mercury (MeHg) and ethyl Hg (EtHg) with oxygen free radicals was studied in vitro by using three well-known hydroxyl radical (OH)-producing systems, namely Cu2+-ascorbate, xanthine oxidase (XOD)-hypoxanthine (HPX)-Fe(III)EDTA and hydrogen peroxide (H2O2)-ultraviolet light B. For this purpose, the direct determination method for inorganic Hg was employed. MeHg and EtHg were readily degraded by these three systems, though the amounts of inorganic Hg generated from MeHg were one half to one third those from EtHg. Degradation activity of XOD-HPX-Fe(III)EDTA system was inhibited by Superoxide dismutase, catalase and the OH scavengers and stimulated by H2O2. Deletion of the OH formation promoter Fe(III)EDTA from XOD-HPX-Fe(III)EDTA system resulted in the decreased degradation of MeHg and EtHg, which was enhanced by further addition of the iron chelator diethylenetriamine pentaacetic acid. In all these cases, a good correlation was observed between alkyl Hg degradation and deoxyribose oxidation determining OH. By contrast, their degradation appeared to be unrelated to either Superoxide anion
production or H2O2 production alone. We further confirmed that H2O2 (below 2 mM) itself did not cause significant degradation of MeHg and EtHg. These results suggested that OH, but not
and H2O2, might be the oxygen free radical mainly responsible for the degradation of MeHg and EtHg. 相似文献
108.
Role of expression of focal adhesion kinase in progression of hepatocellular carcinoma. 总被引:9,自引:0,他引:9
Shinji Itoh Takashi Maeda Mitsuo Shimada Shin-ichi Aishima Ken Shirabe Shinji Tanaka Yoshihiko Maehara 《Clinical cancer research》2004,10(8):2812-2817
PURPOSE: Although hepatocellular carcinoma (HCC) is the most common cancer of the human liver, the mechanisms that regulate HCC development and progression remain unclear. The aim of this study was to investigate whether focal adhesion kinase (FAK) is involved in the progression of human HCC. EXPERIMENTAL DESIGN: Western blot analysis for FAK was performed on three HCC cell lines. We reviewed 64 consecutive patients who had undergone initial liver resection for HCC without preoperative treatment. Immunohistochemistry analysis for FAK was performed on paraffin-embedded tissues. FAK expression was confirmed by Western blot analysis in several clinical samples. We investigated the correlation between FAK expression and clinical outcome. RESULTS: FAK proteins were detected in all HCC cell lines. Hepatocytes in the normal liver and chronic hepatitis with or without cirrhosis were negative for immunohistochemical staining for FAK expression. Cytoplasmic FAK expression was observed in 18 of 64 patients (28.1%), and this positive staining was correlated with gender (P < 0.05), a lower level of serum albumin (P < 0.05), and portal venous invasion (P < 0.01). Positive staining for FAK was associated with significantly poorer survival (P < 0.05). In multivariate analysis, FAK overexpression was an independent factor in determining the prognosis of patients. CONCLUSIONS: These data suggest that FAK plays an important role in promoting tumor progression, especially vascular invasion, in HCC. FAK could play an important role in HCC progression and would be a novel target for HCC therapeutics as well as a prognostic marker. 相似文献
109.
Regulation of p27 by S-phase kinase-associated protein 2 is associated with aggressiveness in non-small-cell lung cancer. 总被引:13,自引:0,他引:13
Atsushi Osoegawa Ichiro Yoshino Shinji Tanaka Kenji Sugio Toshifumi Kameyama Masafumi Yamaguchi Yoshihiko Maehara 《Journal of clinical oncology》2004,22(20):4165-4173
PURPOSE: The F-box protein S-phase kinase-associated protein 2 (Skp2) is one of the positive regulators of the cell cycle that promote ubiquitin-mediated proteolysis of the cyclin-dependent kinase inhibitor p27. In this study, we investigated the significance of Skp2 expression in human non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Clinicopathologic features and immunohistochemical expression of Skp2 and p27 proteins were studied in 138 patients with NSCLC. Survival analyses were performed using the Kaplan-Meier method and the Cox regression model. To analyze the role of Skp2 in vitro, NSCLC cells were transfected with an Skp2-expressing vector or small interfering RNA. RESULTS: Skp2 was overexpressed in males, smokers, patients with squamous cell carcinomas, and patients with poorly differentiated cancers (P = .034, < .0001, < .0001, and .002, respectively). The multivariant analysis revealed that Skp2 expression is an independent prognostic factor for survival in NSCLC. An inverse relationship of Skp2 with p27 expression was observed (P = .012), and patients with both a higher expression of Skp2 and a lower expression of p27 showed a significantly unfavorable prognosis (P = .0002). In vitro ectopic expression of Skp2 in NSCLC cells reduced the protein level of p27. Conversely, induction of Skp2 siRNA increased the protein level of p27, leading to growth inhibition in NSCLC cells. CONCLUSION: Skp2 overexpression is closely associated with the suppression of p27 and the aggressiveness in NSCLC. It also could be a therapeutic target in NSCLC. 相似文献
110.
The human T-cell factor-4 gene splicing isoforms, Wnt signal pathway, and apoptosis in renal cell carcinoma. 总被引:4,自引:0,他引:4