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   17693篇
  免费   1466篇
  国内免费   931篇
耳鼻咽喉   154篇
儿科学   233篇
妇产科学   337篇
基础医学   2134篇
口腔科学   353篇
临床医学   2304篇
内科学   2754篇
皮肤病学   271篇
神经病学   876篇
特种医学   563篇
外国民族医学   7篇
外科学   1931篇
综合类   2692篇
现状与发展   1篇
一般理论   11篇
预防医学   979篇
眼科学   425篇
药学   1764篇
  8篇
中国医学   697篇
肿瘤学   1596篇
  2024年   62篇
  2023年   275篇
  2022年   631篇
  2021年   747篇
  2020年   555篇
  2019年   548篇
  2018年   597篇
  2017年   491篇
  2016年   450篇
  2015年   749篇
  2014年   916篇
  2013年   930篇
  2012年   1320篇
  2011年   1435篇
  2010年   942篇
  2009年   751篇
  2008年   919篇
  2007年   950篇
  2006年   917篇
  2005年   866篇
  2004年   634篇
  2003年   576篇
  2002年   426篇
  2001年   389篇
  2000年   394篇
  1999年   464篇
  1998年   304篇
  1997年   308篇
  1996年   229篇
  1995年   196篇
  1994年   161篇
  1993年   105篇
  1992年   119篇
  1991年   90篇
  1990年   82篇
  1989年   66篇
  1988年   101篇
  1987年   86篇
  1986年   55篇
  1985年   50篇
  1984年   33篇
  1983年   24篇
  1982年   21篇
  1981年   17篇
  1980年   11篇
  1979年   28篇
  1978年   11篇
  1977年   10篇
  1975年   10篇
  1974年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
We generated a novel mouse model of spinal cord injury (SCI) by hemisection of the right L1 lumbar spinal cord, measured the permeability of the blood-spinal cord barrier (BSCB), and tested the hypothesis that tumor necrosis factor alpha (TNF alpha) penetrates the injured BSCB by an enhanced transport system. SCI produced stereotypical sensorimotor deficits resembling the classically described Brown-Seqúard syndrome. Disruption of the BSCB was reflected by increased spinal cord uptake of radiolabeled albumin from blood; this was transient (immediately after SCI) and confined to the lumbar spinal cord. By contrast, specific increase in the entry of TNF alpha was detected in brain, cervical, thoracic, and lumbar spinal cord at 1 week after SCI, in addition to its immediate and transient increase consistent with barrier disruption. Lack of a second peak of increase in the entry of IL1 beta further supported the specificity of the TNF alpha response. Moreover, enhanced uptake of radiolabeled TNF alpha was suppressed by excess non-radiolabeled TNF alpha, indicating competition of entry via the known transport system for TNF alpha. Therefore, upregulation of the transport system after SCI probably mediates the increased permeation of TNF alpha across the BSCB. Enhanced entry of TNF alpha at 1 week after SCI was concurrent with sensorimotor and gait improvement of the mouse. We conclude that SCI by lumbar hemisection activates the transport system for TNF alpha at the BBB and suggest that selective permeation of TNF alpha may facilitate functional recovery.  相似文献   
993.
Lin SM  Tsou MY  Chan KH  Yin YC  Hsin ST  Liao WW  Mok MS  Tsai SK 《Anesthesia and analgesia》2002,95(3):777-9, table of contents
IMPLICATIONS: We report a patient who developed myoclonic seizure in the postanesthesia care unit after thoracic laminectomy. Expeditious diagnostic evaluation of unrecognized dura tear during surgery must be instituted immediately to avoid untoward sequelae. Specific treatment in addition to supportive care is required if the diagnosis is to be clearly identified.  相似文献   
994.
Nan D  Liao W 《中华医学杂志》2002,82(24):1728-1729
我国物理医学与康复专业相对年轻 ,但近年来都有了长足的进步 ,现总结如下。物理医学的重要部分是物理因子在治疗方面的使用与研究。近一年多有数百篇应用物理因子的文章发表 ,多数属于临床疾病的使用观察 ,但是也有不少同行注意进行临床和实验室的基础研究。在磁治疗方面 ,研究了不同磁场强度对人离体血液流变学的影响[1] ,不均匀磁场对小鼠血栓形成及血浆的影响[2 ] ,低频电磁场对人脐静脉内皮细胞增殖的影响[3 ] ,也有脱出原有范围 ,使用运动诱发电位的高强度 (1~ 2tesla)脉冲磁刺激于治疗上的研究 ,华中科大同济医学院同济医院使…  相似文献   
995.
Induction of radioprotective peroxiredoxin-I by ionizing irradiation   总被引:5,自引:0,他引:5  
Results of this study indicate a radioprotective effect of peroxiredoxin-I. Peroxiredoxin-I is an antioxidant that scavenges hydroperoxides, whereas reactive oxygen species are the main mediators of ionizing radiation toxicity. We hypothesized that peroxiredoxin-I might be induced by cellular exposure to radiation and act to protect them against its cytotoxic effects. Western blot and Northern blot analyses were used to assess peroxiredoxin-I protein and mRNA expression. Rat C6 glioma cells were engineered to overexpress sense or antisense human peroxiredoxin-I using retroviral vectors. Clonogenic cell survival was used to assess radiosensitivities of the engineered cells. Ionizing radiation induced peroxiredoxin-I protein and mRNA expression in human HT29 colon cancer and rat C6 glioma cells in a dose- and time-dependent manner over a 24 hr period. To determine the effect of peroxiredoxin-I on radiation responses, C6 glioma cells were engineered to overexpress sense or antisense human peroxiredoxin-I. In clonogenic assays, cells overexpressing peroxiredoxin-I were more radioresistant. Cells transduced with antisense peroxiredoxin-I were marginally more sensitive to radiation toxicity. Irradiation can induce peroxiredoxin-I expression, and the increased peroxiredoxin-I may protect cells from further radiation damage. These results suggest that protection by peroxiredoxin-I may play an important role in the survival of glioma and colon cancer cells in patients undergoing radiation therapy.  相似文献   
996.
Papazisi L  Silbart LK  Frasca S  Rood D  Liao X  Gladd M  Javed MA  Geary SJ 《Vaccine》2002,20(31-32):3709-3719
The aim of this study was to assess the efficacy of a modified live Mycoplasma gallisepticum vaccine (GT5) for the protection of chickens against infection and respiratory disease. GT5 was constructed by the reconstitution of the avirulent high passage R (R(high)) strain with the gene encoding the major cytadhesin GapA. GT5 expressed GapA on its surface yet retained the phenotypic characteristics of the parental R(high) strain. Birds vaccinated with GT5 were protected upon challenge with the virulent low passage R (R(low)) strain as evidenced by a complete absence of tracheal lesions 2 and 4 weeks post-challenge, in contrast to sham immunized/challenged control birds. Modest amounts of IgG, and little, if any secretory IgA or IgM anti-M. gallisepticum were found in tracheal washings following vaccination. However, copious amounts of specific IgA were found following challenge, especially in sham immunized birds. This suggests that the tracheal IgG elicited by GT5 vaccination may have been responsible for blocking the initial colonization of R(low), thereby resulting in protection.  相似文献   
997.
Li N  Chen X  Liao J  Yang G  Wang S  Josephson Y  Han C  Chen J  Huang MT  Yang CS 《Carcinogenesis》2002,23(8):1307-1313
Tea is one of the most popular beverages consumed in the world. Curcumin, the major yellow pigment in turmeric, is used widely as a spice and food-coloring agent. In this study, we studied the effects of tea and curcumin on 7,12-dimethylbenz[a]anthracene (DMBA)-induced oral carcinogenesis in hamsters. DMBA solution (0.5% in mineral oil, 0.1 ml) was applied topically to the left cheek pouch of male Syrian golden hamsters 3 times/week for 6 weeks. Two days after the last treatment of DMBA, the animals received green tea (6 mg tea solids/ml) as drinking fluid, or 10 mmol curcumin applied topically 3 times/week, or the combination of green tea and curcumin treatment, or no treatment for 18 weeks. The combination of tea and curcumin significantly decreased the oral visible tumor incidence from 92.3% (24/26) to 69.2% (18/26) and the squamous cell carcinoma (SCC) incidence from 76.9% (20/26) to 42.3% (11/26). The combination of tea and curcumin also decreased the number of visible tumors and the tumor volume by 52.4 and 69.8%, as well as the numbers of SCC, dysplasic lesions and papillomas by 62.0, 37.5 and 48.7%, respectively. Green tea or curcumin treatment decreased the number of visible tumors by 35.1 or 39.6%, the tumor volume by 41.6 or 61.3% and the number of SCC by 53.3 or 51.3%, respectively. Green tea also decreased the number of dysplasic lesions. Curcumin also significantly decreased the SCC incidence. Tea and curcumin, singly or in combination, decreased the proliferation index in hyperplasia, dysplasia and papillomas. Only the combination treatment decreased the proliferation index in SCC. Tea alone and in combination with curcumin significantly increased the apoptotic index in dysplasia and SCC. Curcumin, alone and in combination with tea, significantly inhibited the angiogenesis in papilloma and SCC. The results suggested that green tea and curcumin had inhibitory effects against oral carcinogenesis at the post-initiation stage and such inhibition may be related to the suppression of cell proliferation, induction of apoptosis and inhibition of angiogenesis.  相似文献   
998.
Spinal cord injury is a major cause of disability and results in many serious physical, psychological, and social difficulties. Numerous studies have shown that traumatic spinal cord injuries (SCI) lead to neuronal loss and axonal degeneration in and around the injury site that cause partial disability or complete paralysis. An important strategy in the treatment of SCI is to promote neuron survival and axon outgrowth, making possible the recovery of neural connections. Using an in vitro survival assay, we have identified ginsenosides Rb1 and Rg1, extracted from ginseng root (Panax ginseng C. A. Meyer), as efficient neuroprotective agents for spinal cord neurons. These compounds protect spinal neurons from excitotoxicity induced by glutamate and kainic acid, as well as oxidative stress induced by H(2)O(2). The neuroprotective effects are dose-dependent. The optimal doses are 20-40 microM for ginsenosides Rb1 and Rg1. The effects are specific for Rb1 and Rg1, since a third ginsenoside, Re, did not exhibit any activity. Ginseng has been used for thousands of years in the treatment of neurological disorders and other diseases in Asia. Ginsenosides Rb1 and Rg1 represent potentially effective therapeutic agents for spinal cord injuries.  相似文献   
999.
Background: Granuloma gluteale infantum is a skin disorder of controversial etiology manifested clinically by oval reddish-purple granulomatous nodules on the gluteal surfaces and groin areas of infants. Similar granulomas are noted in adults and the elderly and are referred to as granuloma gluteale adultorum and diaper area granuloma of the aged, respectively. Occlusion from diapers, paper napkins, plastic pants, detergents, starch, powder, halogenated steroids, candidal infection, and urine and feces are postulated as possible etiologies. Objective: We report a case of a 40-year-old woman presenting with a 3-year history of multiple, painful, closely set, red-purple, oval, smooth, firm papules and nodules in the genitocrural area. The development of the lesions was associated with prolonged use of topical benzocaine. Histology of the lesions was consistent with granuloma gluteale infantum. Gram stain and culture of representative tissue did not demonstrate bacterial or fungal organisms. The lesions significantly improved with discontinuation of topical benzocaine. Patch testing of skin to determine allergic contact hypersensitivity to benzocaine was negative. Conclusion: We propose that topical benzocaine preparations may play a role in the pathogenesis of granuloma gluteale adultorum, independent of contact sensitization to benzocaine.  相似文献   
1000.
SKH-1 hairless mice were irradiated with ultraviolet B (UVB) twice weekly for 20 weeks. These tumor-free mice, which had a high risk of developing skin tumors during the next several months, were then treated topically with caffeine (6.2 micromol) or (-)-epigallocatechin gallate (EGCG; 6.5 micromol) once a day 5 days a week for 18 weeks in the absence of further treatment with UVB. Topical applications of caffeine to these mice decreased the number of nonmalignant and malignant skin tumors per mouse by 44% and 72%, respectively. Topical applications of EGCG decreased the number of nonmalignant and malignant tumors per mouse by 55% and 66%, respectively. Immunohistochemical analysis showed that topical applications of caffeine or EGCG increased apoptosis as measured by the number of caspase 3-positive cells in nonmalignant skin tumors by 87% or 72%, respectively, and in squamous cell carcinomas by 92% or 56%, respectively, but there was no effect on apoptosis in nontumor areas of the epidermis. Topical applications of caffeine or EGCG had a small inhibitory effect on proliferation in nonmalignant tumors as measured by BrdUrd labeling (16-22%), and there was also a similar, but nonsignificant, inhibitory effect on proliferation in malignant tumors. The results suggest a need for further studies to determine whether topical applications of caffeine or EGCG can inhibit sunlight-induced skin cancer in humans.  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