首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1766962篇
  免费   133028篇
  国内免费   6712篇
耳鼻咽喉   22417篇
儿科学   56785篇
妇产科学   46661篇
基础医学   258878篇
口腔科学   46679篇
临床医学   160643篇
内科学   352709篇
皮肤病学   41511篇
神经病学   137553篇
特种医学   71266篇
外国民族医学   323篇
外科学   272858篇
综合类   37710篇
现状与发展   4篇
一般理论   509篇
预防医学   138899篇
眼科学   38229篇
药学   127239篇
  6篇
中国医学   3155篇
肿瘤学   92668篇
  2018年   17901篇
  2016年   16569篇
  2015年   18471篇
  2014年   25486篇
  2013年   38080篇
  2012年   48662篇
  2011年   52834篇
  2010年   32336篇
  2009年   30935篇
  2008年   48956篇
  2007年   52834篇
  2006年   53342篇
  2005年   51541篇
  2004年   49689篇
  2003年   48195篇
  2002年   45970篇
  2001年   82734篇
  2000年   84961篇
  1999年   70847篇
  1998年   20822篇
  1997年   18449篇
  1996年   19397篇
  1995年   19341篇
  1994年   17920篇
  1993年   16936篇
  1992年   58110篇
  1991年   58211篇
  1990年   56450篇
  1989年   54282篇
  1988年   50174篇
  1987年   49542篇
  1986年   46457篇
  1985年   44815篇
  1984年   33973篇
  1983年   28675篇
  1982年   17262篇
  1981年   15561篇
  1980年   14737篇
  1979年   30910篇
  1978年   22365篇
  1977年   18658篇
  1976年   17814篇
  1975年   19346篇
  1974年   22455篇
  1973年   21490篇
  1972年   19838篇
  1971年   18437篇
  1970年   17040篇
  1969年   15926篇
  1968年   14899篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
72.
Erythropoietin exerts hematopoietic effects by stimulating proliferation of early erythroid precursors. Nonhematopoietic effects of erythropoietin have also been shown. It may act as a new angiogenic factor in wound healing. This study aimed to investigate the effect of systemic administration of recombinant human erythropoietin on wound healing in mice. Dorsal incisional wounds were performed in mice, which were then divided into two groups; a group treated for 7 days with recombinant human erythropoietin, and a control group. Sacrificing animals on day 7, the wound tissues were collected for analysis of wound breaking strength, malondialdehyde, a marker of lipid peroxidation, hydroxyproline, an index of reparative collagen deposition, reduced glutathione levels, and for histological evaluation. The immunohistochemical determination of vascular endothelial growth factor (VEGF) which is believed to be the most prevalent angiogenic factor throughout the skin repair process, was also studied. The treatment significantly increased wound breaking strength by decreasing malondialdehyde and increasing hydroxyproline levels on day 7 after wounding. No statistically meaningful change was observed in reduced glutathione content. VEGF was immunostained significantly more on wound tissue of treated animals compared to the control group. Recombinant human erythropoietin treatment may be effective in wound healing due to inhibition of lipid peroxidation, deposition of collagen, and VEGF expression in wound area.  相似文献   
73.
For many parents stopping life-sustaining medical treatment on their dying infant is psychologically impossible. Dostoevsky's insights into human behavior, particularly the fact that individuals do not want the anxiety and guilt associated with responsibility for making difficult decisions, might change the way physicians approach parents for permission to withdraw life-prolonging medical interventions on dying infants.  相似文献   
74.
Molecular characterization of Wuchereria bancrofti is essential to develop suitable anti-filarial drugs and vaccines. We describe here isolation, sequence analysis and cloning of a partial cDNA of an enzyme superoxide dismutase from this parasite. The immunoscreening of a lambda zap W. bancrofti microfilarial (Mf) cDNA library with microfilaremic sera had resulted in the isolation of several seroreactive clones including, WbSOD. This clone contained a 309 bp insert and showed significant nucleotide and deduced amino acid sequence homologies to the superoxide dismutases of other nematode parasites. The antioxidant property of this enzyme may have important contribution in the defense mechanism of the parasite against host immune response.  相似文献   
75.
Four clinical trials of porcine islet transplantation have been reported, and there are verbal reports that clinical trials on much larger scales are continuing in centers in China and Russia. The four reported trials are briefly reviewed and, in the light of the present status of experimental islet xenotransplantation, consideration is given to whether such trials are currently justified. The Ethics Committee of the International Xenotransplantation Association has (1) emphasized the need for encouraging studies in non-human primates before clinical trials should be undertaken, (2) mandatory monitoring for the transfer of porcine microorganisms, and (3) careful regulation and oversight by recognized bodies. Other aspects of the topic, such as the need for informed consent, are briefly discussed. We conclude that, at the present time, more data documenting convincing efficacy, focused on clinically applicable immunosuppressive regimens, are needed to justify the initiation of closely monitored clinical trials. A clinical trial may then be justified even though the potential risk to the patients, and possibly for society, will not be zero.  相似文献   
76.
Summary: The mosaic (Atp7a mo-ms ) is an X-linked, lethal mutation in mice. In mosaic mutant males, many clinical features characteristic of defective copper metabolism have been observed and they die at the age of 15 days, exhibiting strongsimilarities to the brindled and macular mutants. About 4% of the mutant males live to sexual maturity and some of them are fertile. In this paper, alterationsin the structure of the kidney from adult mutants are described. Owing to an inherited defect of efflux, copper is accumulated in the kidney of the mutants up to a toxic level and this leads to severe damage of the renal cortex. Pathological changes in the kidney mostly affected the structure of the renal corpuscle and renaltubules.  相似文献   
77.
78.
79.
80.
OBJECTIVE: A safe entry zone to tegmental lesions was identified based on intraoperative electrophysiological findings, the compound muscle action potentials (CMAP) from the extraocular muscles, and anatomic considerations. This entry zone is bordered caudally by the intramesencephalic path of the trochlear, laterally by the spinothalamic tract, and rostrally by the caudal margin of the brachium of the superior colliculus. METHODS: Four intrinsic midbrain lesions were operated upon via the safe entry zone using the infratentorial paramedian supracerebellar approach. All lesions involved the tegmentum and included an anaplastic astrocytoma, a metastatic brain tumor, a radiation necrosis, and a cavernous angioma. CMAP were bilaterally monitored from the inferior recti (for oculomotor function) and superior oblique (for trochlear nerve function) muscles. RESULTS: In three of four cases, CMAP related to the oculomotor nerve were obtained upon stimulation at the cavity wall after removal of the tumor. Stimulation at the surface of the quadrigeminal plate, however, did not cause any CMAP response. Using this monitoring as an indicator, the lesions were totally removed. CONCLUSIONS: In the surgery of tegmental lesions, CMAP monitoring from extraocular muscles is particularly helpful to prevent damage to crucial neural structures during removal of intrinsic lesions, but less so to select the site of the medullary incision. The approach via the lateral part of the colliculi is considered to be a safe route to approach the tegmental lesions.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号