全文获取类型
收费全文 | 1763122篇 |
免费 | 120558篇 |
国内免费 | 3450篇 |
专业分类
耳鼻咽喉 | 25678篇 |
儿科学 | 54515篇 |
妇产科学 | 49822篇 |
基础医学 | 259332篇 |
口腔科学 | 52028篇 |
临床医学 | 150602篇 |
内科学 | 337394篇 |
皮肤病学 | 40049篇 |
神经病学 | 135446篇 |
特种医学 | 68574篇 |
外国民族医学 | 492篇 |
外科学 | 271838篇 |
综合类 | 37990篇 |
现状与发展 | 6篇 |
一般理论 | 539篇 |
预防医学 | 125872篇 |
眼科学 | 41907篇 |
药学 | 133971篇 |
4篇 | |
中国医学 | 3798篇 |
肿瘤学 | 97273篇 |
出版年
2018年 | 15835篇 |
2015年 | 15549篇 |
2014年 | 21670篇 |
2013年 | 33155篇 |
2012年 | 43743篇 |
2011年 | 46955篇 |
2010年 | 27755篇 |
2009年 | 26660篇 |
2008年 | 45040篇 |
2007年 | 49032篇 |
2006年 | 49784篇 |
2005年 | 48155篇 |
2004年 | 46886篇 |
2003年 | 45329篇 |
2002年 | 44713篇 |
2001年 | 81791篇 |
2000年 | 84408篇 |
1999年 | 71035篇 |
1998年 | 19070篇 |
1997年 | 17258篇 |
1996年 | 16950篇 |
1995年 | 15947篇 |
1994年 | 14933篇 |
1992年 | 55163篇 |
1991年 | 54513篇 |
1990年 | 54021篇 |
1989年 | 52562篇 |
1988年 | 48929篇 |
1987年 | 48219篇 |
1986年 | 46051篇 |
1985年 | 43854篇 |
1984年 | 32854篇 |
1983年 | 27961篇 |
1982年 | 16510篇 |
1981年 | 15097篇 |
1980年 | 14103篇 |
1979年 | 31815篇 |
1978年 | 22895篇 |
1977年 | 19721篇 |
1976年 | 18213篇 |
1975年 | 20883篇 |
1974年 | 24742篇 |
1973年 | 23762篇 |
1972年 | 22938篇 |
1971年 | 21603篇 |
1970年 | 20319篇 |
1969年 | 19532篇 |
1968年 | 18321篇 |
1967年 | 16487篇 |
1966年 | 15160篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The use of additional epidural sympathetic block during and after microvascular surgery in the lower extremities to prevent vasospasm is generally agreed on. However, a significant fall in the perfusion rate of the transplants was seen after application of bupivacaine (Marcain) via the epidural catheter. This effect has, to our knowledge, not been described before and is probably caused by the sympathectomy effect of this type of analgesia. 相似文献
102.
B A Thornhill H T Morehouse J C Hoffman-Tretin 《Critical reviews in diagnostic imaging》1988,28(1):1-22
Computed tomography (CT) is currently the imaging modality of choice for assessing the morphology of the adrenal glands in adult patients. Much useful information can be gained using CT in disease processes which primarily involve one or both of the adrenal glands, such as adenomas, as well as in entities which secondarily affect the adrenals, such as pituitary or metastatic disease. The size and configuration of the glands can be readily determined, and masses may be detected. We discuss CT of normal and abnormal adrenal glands with sonographic (US) and pathological correlation, when available. Entities which may mimic adrenal abnormalities are emphasized. Relative advantages of US over CT in the pediatric patient are discussed. 相似文献
103.
Milton G. Mutchnick MD Horchang H. Lee MD 《Alcoholism, clinical and experimental research》1988,12(1):155-158
Concanavalin A-induced lymphocyte proliferation was studied in 25 patients with alcoholic hepatitis or compensated alcoholic cirrhosis. Nine alcoholics without evidence of liver disease were also evaluated. A nonlinear correlation equation, which was natural logarithmic, was applied to individual dose-response proliferation curves and permitted comparisons between patient groups and controls. The proliferative response in all patient groups was significantly lower when compared to healthy controls and was independent of the presence or absence of liver disease. This suggests that some changes in immune function observed in alcoholics may be linked to the direct effects of alcohol on the immune system rather than to the associated liver disease. 相似文献
104.
Steven Kaddu H. Peter Soyer Ingrid H. Wolf Helmut Kerl 《Journal of cutaneous pathology》1997,24(4):228-234
We report on 9 patients with pilomatricomas that showed unusual histopathologic features. Our patients were mainly elderly individuals (age range 42 to 88 years; mean age 70.1 years) who presented solitary cutaneous nodules situated on the head and neck (7 neoplasms), upper arm (1 neoplasm), and back (1 neoplasm). All the lesions were treated by simple excision. Follow-up data available in 7 of the 9 patients (mean follow-up, 17 months) revealed local recurrences in 1 patient whose lesion recurred 3 times. No lymph node involvement or distant metastases were recorded in any of our cases. Histopathologically, most neoplasms were characterized by a relatively large lesion in the clermis that in some cases showed extension to the subcutis. Each lesion was predominantly composed of a lobular proliferation of basaloid cells in association with adjacent focal areas containing eosinophilic, cornified material with shadow cells. In some cases, relatively large areas of shadow cells were present, whereas, in others only small foci of shadows cells were observed. Cytomorphologically, the basaloid cells showed features of matrical and supramatrical cells of a normal hair follicle and exhibited variable nuclear atypia and mitotic figures. The overall architectural pattern of the neoplasms was different from that of large fully developed stereotypical pilomatricomas that maintain a cystic character with basaloid cells predominantly aligned at the periphery. Based on the histopathologic findings, namely the presence of a large, lobular proliferation of basaloid cells in association with small to large foci of shadow cells, we interpreted these neoplasms to be a distinctive proliferative variant of pilomatricoma and propose the designation "proliferating pilomatricoma." Proliferating pilomatricomas should be differentiated from the recently described matricoma, basal-cell carcinoma with matrical differentiation, and matrical carcinoma (pilomatrical carcinoma). 相似文献
105.
106.
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
107.
108.
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
109.
J Grogan B H Nowicki T A Schmidt V M Haughton 《AJNR. American journal of neuroradiology》1997,18(7):1325
PURPOSETo study the relationship of lumbar facet joint tropism to degeneration of the cartilage and subcortical bone in the facet joints and the effect of tropism in intervertebral disk degeneration.METHODSThe orientation of 104 cadaveric lumbar facet joints with respect to sagittal plane was measured on CT scans, and the joints were classified as having no tropism, mild tropism, or severe tropism. On MR images, the severity of cartilage degeneration and bony sclerosis was measured. The correlation between tropism and degeneration was calculated, as was the relationship among age, spinal level, and degeneration.RESULTSWe identified four spinal levels with severe tropism, six with moderate tropism, and 94 without tropism. Cartilage degeneration was not significantly more severe in the joints with tropism than in the joints without. Sclerosis was slightly greater in the joints with tropism than in the joints without it. Sclerosis and cartilage degeneration were significantly related to age and spinal level.CONCLUSIONAge, spinal level, and overall facet joint angle are more important factors in facet joint degeneration than is tropism. 相似文献
110.
K. Sjölund S. Fasth R. Ekman L. Hultén H. Jiborn S. Nordgren & F. Sundler 《Neurogastroenterology and motility》1997,9(3):143-150
Tissue specimens from the large bowel of 18 patients with long-standing slow transit constipation were investigated to determine the distribution and density of several neuropeptides and amines in the enteric nerve system, and also of endocrine cells in comparison to normal individuals. CGRP (calcitonin gene-related peptide), galanin, glucagon, GRP (gastrin-releasing peptide), metenkephalin, motilin, neuropeptide Y (NPY), PACAP, peptide YY (PYY), serotonin, somatostatin, substance P and VIP were studied by immunohistochemistry. Tissue concentrations of VIP, substance P and galanin were also measured by radioimmunoassay. Significantly increased VIP, SP and galanin contents were found in specimens from the ascending colon. Levels of VIP and galanin were also increased in the transverse colon. Immunohistochemistry revealed only marginal changes with an increased density of PACAP nerve fibres in the smooth muscle and of VIP and PACAP nerves in the myenteric plexus of the transverse colon. In the descending colon substance P and NPY immunoreactivity were also increased in the myenteric plexus while the density of VIP nerve fibres was reduced in the mucosa/submucosa. The frequency of PYY-containing cells and the 5-HT-containing cells in the ascending colon was significantly increased in the constipated patients. 相似文献