全文获取类型
收费全文 | 2584662篇 |
免费 | 189167篇 |
国内免费 | 7572篇 |
专业分类
耳鼻咽喉 | 34351篇 |
儿科学 | 85344篇 |
妇产科学 | 71641篇 |
基础医学 | 363640篇 |
口腔科学 | 69677篇 |
临床医学 | 234614篇 |
内科学 | 515767篇 |
皮肤病学 | 62483篇 |
神经病学 | 213546篇 |
特种医学 | 99933篇 |
外国民族医学 | 736篇 |
外科学 | 386733篇 |
综合类 | 50407篇 |
现状与发展 | 5篇 |
一般理论 | 968篇 |
预防医学 | 196204篇 |
眼科学 | 56718篇 |
药学 | 188020篇 |
8篇 | |
中国医学 | 5331篇 |
肿瘤学 | 145275篇 |
出版年
2021年 | 20003篇 |
2019年 | 20638篇 |
2018年 | 29320篇 |
2017年 | 22616篇 |
2016年 | 26274篇 |
2015年 | 29539篇 |
2014年 | 40492篇 |
2013年 | 60490篇 |
2012年 | 80316篇 |
2011年 | 84588篇 |
2010年 | 51065篇 |
2009年 | 49190篇 |
2008年 | 79128篇 |
2007年 | 83955篇 |
2006年 | 85681篇 |
2005年 | 81882篇 |
2004年 | 78837篇 |
2003年 | 76113篇 |
2002年 | 73386篇 |
2001年 | 128429篇 |
2000年 | 131353篇 |
1999年 | 110513篇 |
1998年 | 31253篇 |
1997年 | 27925篇 |
1996年 | 28218篇 |
1995年 | 27385篇 |
1994年 | 25068篇 |
1993年 | 23419篇 |
1992年 | 85161篇 |
1991年 | 81563篇 |
1990年 | 78785篇 |
1989年 | 76059篇 |
1988年 | 69469篇 |
1987年 | 67997篇 |
1986年 | 63545篇 |
1985年 | 60512篇 |
1984年 | 44942篇 |
1983年 | 37943篇 |
1982年 | 22456篇 |
1981年 | 19985篇 |
1979年 | 38959篇 |
1978年 | 27442篇 |
1977年 | 23252篇 |
1976年 | 21495篇 |
1975年 | 22814篇 |
1974年 | 26786篇 |
1973年 | 25370篇 |
1972年 | 23750篇 |
1971年 | 21956篇 |
1970年 | 20184篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Repeated survey on changes in musculoskeletal complaints relative to age and work demands. 总被引:3,自引:3,他引:0
下载免费PDF全文
![点击此处可从《Occupational and environmental medicine》网站下载免费的PDF全文](/ch/ext_images/free.gif)
B C de Zwart J P Broersen M H Frings-Dresen F J van Dijk 《Occupational and environmental medicine》1997,54(11):793-799
OBJECTIVES: To examine changes in musculoskeletal complaints over four years in groups of employees relative to age and work demands. METHODS: Repeated questionnaire data of male employees in heavy physical work (exposed group, n = 7324) and mental work (control group, n = 4686), stratified for age (20-9, 30-9, 40-9, 50-9), were analysed. For each employee, data on the occurrence of musculoskeletal complaints from two surveys with a mean interval of around four years were available. Changes in prevalences over the follow up interval were analysed. Proportions of new, recovered, and chronic cases as well as those free of complaints at both surveys were studied. RESULTS: For most complaints, there were significantly greater increases in prevalences in the exposed group compared with the control group over the follow up interval particularly within the group aged 40-9 for back, neck, and several sites of the upper and lower limbs. The 20-9 year age group also had significantly greater changes for several musculoskeletal complaints. Within the oldest age group (50-9) exposure to heavy physical work demands only affected changes in prevalences of neck and upper arm complaints. After four years in the cohort free of complaints at the start of the follow up the group aged 40-9 had the highest prevalence of complaints of the back, neck, and the upper and lower limbs. CONCLUSIONS: Middle aged and younger employees develop musculoskeletal complaints as a result of exposure to heavy physical work. In the oldest age group health related selection seems to mask the occupational health risks under study. To prevent the expected increase in musculoskeletal disorders and related work disability in our aging workforce, preventive measures should be taken at all stages of a working life. 相似文献
942.
C. R. Irwin T. Myrillas M. Smyth J. Doogan C. Rice S. L. Schor 《Journal of oral pathology & medicine》1998,27(6):255-259
Fibroblasts incorporated within collagen gels induce a cell-mediated contraction of the gel to form a three-dimensional, tissue-like structure by a mechanism thought to mimic wound contraction in vivo . In this study a gel contraction model was used to investigate the ability of fibroblasts derived from adult gingiva, adult skin and fetal skin to organise a collagen matrix. In addition the effects of interleukin-1β (IL-1β) on the contraction process was also investigated. Over the concentration range 5-50 U/ml, IL-1β induced a statistically significant inhibition of gel contraction in all fibroblast cell types ( P <0.05), although fetal fibroblasts appeared least responsive and gingival fibroblasts most responsive to the inhibitory effects of this cytokine. Comparison of gel contraction by the different fibroblast strains indicated that fetal and gingival fibroblasts shared similar contraction kinetics. For the adult skin fibroblasts, three of five strains studied showed significantly diminished levels of gel contraction compared to fetal and gingival cells. This apparent difference in fibroblast phenotype may, at least in part, explain the fetal-like wound healing pattern seen in the oral mucosa. 相似文献
943.
A. HAZIOT I. KATZ G. W. RONG X. Y. LIN J. SILVER & S. M. GOYERT 《Scandinavian journal of immunology》1997,46(3):242-245
Membrane-bound CD14 acts as a receptor for lipopolysaccharide (LPS) on monocytes/macrophages and neutrophils. Studies have suggested that the activation of monocytes/macrophages by the binding of LPS to membrane-bound CD14 may require the association of a signal-transducing molecule with membrane-bound CD14. The observation that non-CD14 expressing cells, such as endothelial cells, can nevertheless be activated by a complex of LPS and a soluble form of CD14 (sCD14) suggests that the receptor for this complex may be identical to the signal transducing molecule associated with membrane-bound CD14. The studies described show that two CD14-specific MoAb are able to block the LPS-induced activation of endothelial cells but do not affect the response of monocytes to LPS. This suggests that the interaction of the sCD14:LPS complex with endothelial cells is distinct from the interaction of membrane-bound CD14 with its putative signal-transducing molecule. 相似文献
944.
Plasmid DNA encoding transforming growth factor-beta1 suppresses chronic disease in a streptococcal cell wall-induced arthritis model. 总被引:6,自引:0,他引:6
下载免费PDF全文
![点击此处可从《The Journal of clinical investigation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
X Y Song M Gu W W Jin D M Klinman S M Wahl 《The Journal of clinical investigation》1998,101(12):2615-2621
Transforming growth factor beta is a potent immunomodulator with both pro- and antiinflammatory activities. Based on its immunosuppressive actions, exogenous TGF-beta has been shown to inhibit autoimmune and chronic inflammatory diseases. To further explore the potential therapeutic role of TGF-beta, we administered a plasmid DNA encoding human TGF-beta1 intramuscularly to rats with streptococcal cell wall-induced arthritis. A single dose of 300 microg plasmid DNA encoding TGF-beta1, but not vector DNA, administered at the peak of the acute phase profoundly suppressed the subsequent evolution of chronic erosive disease typified by disabling joint swelling and deformity (articular index = 8.17+/-0. 17 vs. 1.25+/-0.76, n = 6, day 26, P < 0.01). Moreover, delivery of the TGF-beta1 DNA even as the chronic phase commenced virtually eliminated subsequent inflammation and arthritis. Both radiologic and histopathologic as well as molecular evidence supported the marked inhibitory effect of TGF-beta1 DNA on synovial pathology, with decreases in the inflammatory cell infiltration, pannus formation, cartilage and bone destruction, and the expression of proinflammatory cytokines that characterize this model. Increases in TGF-beta1 protein were detected in the circulation of TGF-beta1 DNA-treated animals, consistent with the observed therapeutic effects being TGF-beta1 dependent. These observations provide the first evidence that gene transfer of plasmid DNA encoding TGF-beta1 provides a mechanism to deliver this potent cytokine that effectively suppresses ongoing inflammatory pathology in arthritis. 相似文献
945.
946.
947.
Elizabeth Campbell Ph.D. Danna Peterkin R.N. Richard Abbott M.B. B.S. John Rogers M.B. B.S. 《Preventive medicine》1997,26(6):801-807
Background.Computers that collect data from patients and provide both patients and practitioners with printed feedback on a range of health risks are a tool for assisting general practitioners with preventive care. This study assessed the impact of computer-generated printed feedback on cervical screening among women who were underscreened for cervical cancer.Method.Female attenders at two Australian general practices were randomly allocated to Experimental or Control groups. Women in both groups completed a health risk survey on a touch screen computer prior to their consultation. Those in the Experimental group received printed pages summarizing their results, including their eligibility for cervical screening and last Pap test, for themselves and their doctor. The number and proportion of underscreened women who had a Pap test in the 6 months after completing the computer survey, as determined by pathology records, were examined.Results.Of the 679 participants, 139 were classified as underscreened on the basis of self-report (74 Experimental, 65 Control) and 272 on the basis of their pathology records (148 Experimental, 124 Control). Overall about one-third of women had a test in the 6-month period, and the differences between the groups were not significant for women overall (18–70 years) or for women 18–49 years. Among women 50–70 who were underscreened based on self-report, those receiving the printout were more likely to have a Pap test in the next 6 months (P< 0.05). This pattern was also evident, but did not reach statistical significance, for older women who were underscreened based on pathology records.Conclusions.We are unable to draw conclusions regarding the effectiveness of the computer system due to the modest proportions of women screened, the small numbers, and the fact that the computer survey may have created an intervention effect in the Control group. As the study suggests the computer system is acceptable to women and may be effective for encouraging screening among older women, further exploration of the system is desirable. 相似文献
948.
M M Smith J E Thompson D Thomas M Castillo D Carrier S K Mukherji D Gilliam 《AJNR. American journal of neuroradiology》1997,18(2):327
Choristomas, masses of normal tissues in aberrant locations, contain smooth muscle fibers and fibrous tissues. We describe the MR imaging features of two choristomas located in the internal auditory canals and arising from the facial and vestibulocochlear nerves. Both lesions enhanced with contrast material. In one case, enhancement was seen in the geniculate ganglion and greater superficial petrosal nerve. In the other, a medial component enhanced less than the lateral component did. 相似文献
949.
950.
Palytoxin, a highly toxic natural product isolated from zoanthids of the genus Palythoa, is accumulated by a wide range of fishes and marine invertebrates used as food in the Indo-Pacific. It is responsible for many incidents of human morbidity and mortality. The toxin is a potent smooth muscle spasmogen. The cause of the contraction of smooth muscle is unclear, but recent work strongly suggests that it is primarily initiated by the release of neurotransmitters from the motor innervation of the smooth muscle. We show here that palytoxin caused the swelling of the muscle cells and some internal organelles of the anococcygeus muscle of the rat, but no substantial structural damage to the tissue. Axons and Schwann cells were also swollen but the most dramatic feature was the depletion of synaptic vesicles from putative release sites in the axons. Some axons were physically damaged following exposure to the toxin, but this was relatively uncommon (<10% of all axons studied). In the majority of axons there was no damage to nerve terminal membranes, but there was damage to mitochondria. The depletion of vesicles involved all types – clear, dense-cored, large and small. Our observations and pharmacological data gathered elsewhere, provide a neuropathological basis for the spasmogenic activity of palytoxin. 相似文献