全文获取类型
收费全文 | 9445篇 |
免费 | 392篇 |
国内免费 | 96篇 |
专业分类
耳鼻咽喉 | 43篇 |
儿科学 | 120篇 |
妇产科学 | 111篇 |
基础医学 | 1371篇 |
口腔科学 | 118篇 |
临床医学 | 459篇 |
内科学 | 2585篇 |
皮肤病学 | 155篇 |
神经病学 | 845篇 |
特种医学 | 313篇 |
外科学 | 1699篇 |
综合类 | 26篇 |
预防医学 | 243篇 |
眼科学 | 70篇 |
药学 | 599篇 |
中国医学 | 38篇 |
肿瘤学 | 1138篇 |
出版年
2023年 | 46篇 |
2022年 | 89篇 |
2021年 | 126篇 |
2020年 | 81篇 |
2019年 | 99篇 |
2018年 | 151篇 |
2017年 | 122篇 |
2016年 | 131篇 |
2015年 | 156篇 |
2014年 | 216篇 |
2013年 | 284篇 |
2012年 | 409篇 |
2011年 | 526篇 |
2010年 | 301篇 |
2009年 | 301篇 |
2008年 | 525篇 |
2007年 | 529篇 |
2006年 | 548篇 |
2005年 | 598篇 |
2004年 | 599篇 |
2003年 | 651篇 |
2002年 | 672篇 |
2001年 | 169篇 |
2000年 | 163篇 |
1999年 | 205篇 |
1998年 | 199篇 |
1997年 | 178篇 |
1996年 | 145篇 |
1995年 | 130篇 |
1994年 | 141篇 |
1993年 | 131篇 |
1992年 | 113篇 |
1991年 | 113篇 |
1990年 | 113篇 |
1989年 | 118篇 |
1988年 | 106篇 |
1987年 | 68篇 |
1986年 | 63篇 |
1985年 | 47篇 |
1984年 | 55篇 |
1983年 | 50篇 |
1982年 | 58篇 |
1981年 | 51篇 |
1980年 | 45篇 |
1979年 | 33篇 |
1978年 | 37篇 |
1976年 | 23篇 |
1975年 | 23篇 |
1972年 | 17篇 |
1966年 | 18篇 |
排序方式: 共有9933条查询结果,搜索用时 234 毫秒
111.
112.
Goya S Matsuoka H Mori M Morishita H Kida H Kobashi Y Kato T Taguchi Y Osaki T Tachibana I Nishimoto N Yoshizaki K Kawase I Hayashi S 《The Journal of pathology》2003,200(1):82-87
A variety of pathological changes are seen in lymphoproliferative disorders of the lung but the histogenesis of these abnormalities is not yet fully understood. We previously showed that adenovirus vector-mediated transient expression of both the human interleukin-6 (IL-6) and IL-6 receptor (IL-6R) genes, but not the IL-6 gene alone, in the rat lung induced lymphocytic alveolitis. In the present study, we explored the lung pathology of human IL-6 and IL-6R double transgenic mice to elucidate the effects of prolonged IL-6 signalling on the lung. The transgenic animals developed mononuclear cell accumulation in peribronchovascular regions, but little infiltration into alveolar spaces. Immunohistochemical analysis revealed that the cellular accumulations contained not only mixtures of inflammatory cells but also lymphoid tissue-like structures. As the expression of CXCL13/BLC, the indispensable chemokine for lymphoid organogenesis, was recognized in the B cell follicles of the pulmonary lesions, we speculate that this chemokine plays an inductive role in the development of the lymphoid tissue-like structures. These structures were distinguished from bronchus-associated lymphoid tissues (BALTs) by their location and by the lack of lymphoepithelium, which is a characteristic of BALT. These findings imply that IL-6 signalling may play a role in the pathogenesis of lymphoproliferative disorders of the lung. 相似文献
113.
A new approach to spike sorting for multi-neuronal activities recorded with a tetrode--how ICA can be practical 总被引:1,自引:0,他引:1
Multi-neuronal recording with a tetrode is a powerful technique to reveal neuronal interactions in local circuits. However, it is difficult to detect precise spike timings among closely neighboring neurons because the spike waveforms of individual neurons overlap on the electrode when more than two neurons fire simultaneously. In addition, the spike waveforms of single neurons, especially in the presence of complex spikes, are often non-stationary. These problems limit the ability of ordinary spike sorting to sort multi-neuronal activities recorded using tetrodes into their single-neuron components. Though sorting with independent component analysis (ICA) can solve these problems, it has one serious limitation that the number of separated neurons must be less than the number of electrodes. Using a combination of ICA and the efficiency of ordinary spike sorting technique (k-means clustering), we developed an automatic procedure to solve the spike-overlapping and the non-stationarity problems with no limitation on the number of separated neurons. The results for the procedure applied to real multi-neuronal data demonstrated that some outliers which may be assigned to distinct clusters if ordinary spike-sorting methods were used can be identified as overlapping spikes, and that there are functional connections between a putative pyramidal neuron and its putative dendrite. These findings suggest that the combination of ICA and k-means clustering can provide insights into the precise nature of functional circuits among neurons, i.e. cell assemblies. 相似文献
114.
Isao Nakanishi Shogo Katsuda Yoshikatsu Okada Yoshio Oda Fujitsugu Matsubara 《Pathology international》1986,36(2):261-267
Confronting cisternae of the endoplasmic reticulum recognized in tumor cells of 7 cases of osteosarcoma were presented. They were found in the mitotic cells as well as in the cytoplasms of interphase cells. The more the mitotic cells were observed in 1 μm-thick sections, the more frequently those membranous structures were encountered in the corresponding ultrathin sections. In the interphase cells, such structures were located around Golgi apparatus or close to the nucleus. Occasionally, they were composed of a pair of closely apposed cisternae of the nuclear membrane and the rough endoplasmic reticulum. These results seem to indicate that the nuclear envelope which is disrupted and reformed during mitosis in rapidly proliferating cells takes part in the formation of the confronting cisternae of the endoplasmic reticulum. 相似文献
115.
Yoshio Iwakura Katsumi Hayashi Koichi Inagaki 《Macromolecular chemistry and physics.》1967,104(1):56-65
L - and DL-2-Alkyl-2-isocyanatoethyl chloroformates were synthesized by the phosgenation of the corresponding amino alcohols. These optically active or racemic difunctional compounds were submitted to polycondensation-addition with various diamines to form high molecular weight polyurethan-ureas having asymmetric carbon atoms along the main chain. The optically active polyurethan-ureas obtained had slightly higher melting points than the corresponding racemic polymers. 相似文献
116.
Masayuki Amagai Yoshio Inokuchi Takeji Nishikawa Yoshiko Shimizu Nobuyoshi Shimizu 《Somatic Cell and Molecular Genetics》1989,15(2):153-158
The tumor promoter 12-O -tetradecanoylphorbol-13-acetate (TPA) induces DNA synthesis in quiescent 3T3-L1 cells but not in its variant VT-1 cells. A gt10 cDNA library was constructed using poly(A)+ RNA from 3T3-L1 cells that were stimulated by TPA for 20 min. Radioactive cDNA probes were prepared from mRNAs of TPA-treated 3 T3-L1 and VT-1 cells and used for screening of the 3T3-L1 cDNA library by differential hybridization. Nine of 6000 phage plaques hybridized only to the 3T3-L1 cDNA probe. Analysis of the nucleotide sequence of five of these clones indicated a high degree of homology with human or mouse type I and type III collagen genes. Three other independent clones showed no homology with any known DNA sequences. These isolated clones of TPA-inducible early (TIE) genes may be useful to study the signal transduction pathway of phorbol esters. 相似文献
117.
Our study was undertaken to determine whether human recombinant interleukin 1 alpha (rIL 1 alpha) has any effect on the proliferation and expression of HLA-A,B,C antigens of human liver cell lines. The addition of rIL 1 alpha reduced the cell number of the human hepatoma cell line, PLC/PRF/5. This effect was determined to be cytotoxic, but not growth inhibitory, rIL 1 alpha did not change the number of Chang cell or SK-Hep-1 at a concentration as, high as 25,000 U/ml. rIL 1 alpha enhanced the expression of HLA-A,B,C antigens on PLC/PRF/5, but had no effect on Change cell or SK-Hep-1. Receptor binding studies showed that 125I-rIL 1 alpha bound to PLC/PRF/5 in a specific and saturable manner, but did not bind to Chang cell or SK-Hep-1. Scatchard plot analysis of the binding to PLC/PRF/5 revealed a single type of high affinity binding site with an apparent dissociation constant of approximately 5 x 10(-5) M and the presence of approximately 150 binding sites per cell. These findings suggest that IL 1 alpha may play a role in host defense against some hepatomas as cytotoxic factor and may be an enhancer of expression of HLA-A,B,C antigens on tumor cells. 相似文献
118.
Yoshio Maruyama 《Pflügers Archiv : European journal of physiology》1986,407(5):561-563
A phase-sensitive detection method in combination with whole-cell voltage-clamp was applied to exocrine pancreatic acinar cells from rat. The results have shown that cell-aialysis with a solution containing 5×10–7 M Ca2+ induces stp-wise changes in cell capacitance. The size distribution of increasing and decreasing capacitance steps is compatible with the idea that these capacitance steps are the results of individual granular fusion and retrieval events. This method may enable experiments studying the exo-and endo-cytotic mechanisms in morphologically polarized secretory cells. 相似文献
119.
Hyodo T Kanazawa S Dendo S Kobayashi K Hayashi H Kouno Y Fujishima M Hiraki Y 《Acta medica Okayama》2004,58(5):235-240
We compared the thin-section CT findings of 11 intrapulmonary lymph nodes with pathological findings and evaluated the possibility of CT scan differential diagnosis from pulmonary metastatic nodules. First, we retrospectively reviewed CT scan and pathological findings of intrapulmonary lymph nodes. The median size of these nodules was 6.2 mm. The nodules appeared round (n=3) or angular (n=8) in shape with a sharp border, and they were found below the level of the carina. The median distance from the nearest pleural surface was 4.6 mm, and 3 of the 11 nodules were attached to the pleura. On thin-section CT scan, linear densities extending from the intrapulmonary lymph nodes were frequently visualized, and were pathologically proven to be ectatic lymphoid channels. We then compared the thin-section CT findings of 8 metastatic nodules less than 1 cm in diameter with those of the 11 intrapulmonary lymph nodes. The median size of these nodules was 6.8 mm, and the median distance from the nearest pleural surface was 16 mm. All nodules appeared round in shape. None of the nodules had linear densities extending from the nodules. The linear densities on thin-section CT scan may be the most useful characteristic of intrapulmonary lymph nodes, when differential diagnosis from metastatic nodules is necessary. 相似文献
120.
Navia JL Zahr F Fukamachi K Goodin M Ragaller P Chen JF Kopcak MW Dessoffy R Ootaki Y Kamohara K Akiyama M Gutierrez A Navia JA Atik F Cosgrove DM 《ASAIO journal (American Society for Artificial Internal Organs : 1992)》2005,51(6):686-691
Myocardial salvage through coronary sinus intervention has been documented. The AutoRetroPerfusion Cannula is a novel device that is able to perfuse the coronary bed retrogradely through the coronary sinus with arterial blood generated from a peripheral artery with no need for a pump. The cannula consists of a distal end that, once secured in the coronary sinus, opens an umbrella-like membrane to create pressure in the coronary sinus, and at the same time has small channels directed backwards to the right atrium to provide pressure relief. The cannula is introduced from the axillary vein under local anesthesia and the proximal end, which consists of a graft, is anastomosed to the axillary artery to start autoperfusion once the distal end is secured in the coronary sinus and the occluding membrane is open. The AutoRetroPerfusion Cannula was tested in the in vitro mock loop under 50-120 mm Hg of proximal pressure and 50, 100, and 150 ml/min of total flow in the cannula. We were able to achieve the nominal design point of 40-80 mm Hg of distal pressure and 50-150 ml/min of distal flow by adjusting the number, diameter, and length of the small backwards channels. 相似文献