全文获取类型
收费全文 | 640771篇 |
免费 | 36399篇 |
国内免费 | 3420篇 |
专业分类
耳鼻咽喉 | 9344篇 |
儿科学 | 17352篇 |
妇产科学 | 16797篇 |
基础医学 | 90068篇 |
口腔科学 | 18924篇 |
临床医学 | 49233篇 |
内科学 | 131907篇 |
皮肤病学 | 16508篇 |
神经病学 | 50566篇 |
特种医学 | 24711篇 |
外国民族医学 | 132篇 |
外科学 | 100422篇 |
综合类 | 11511篇 |
现状与发展 | 1篇 |
一般理论 | 123篇 |
预防医学 | 34510篇 |
眼科学 | 15332篇 |
药学 | 48968篇 |
1篇 | |
中国医学 | 2873篇 |
肿瘤学 | 41307篇 |
出版年
2021年 | 6371篇 |
2020年 | 4004篇 |
2019年 | 6380篇 |
2018年 | 9910篇 |
2017年 | 7395篇 |
2016年 | 8336篇 |
2015年 | 9319篇 |
2014年 | 12151篇 |
2013年 | 16483篇 |
2012年 | 23768篇 |
2011年 | 23673篇 |
2010年 | 14095篇 |
2009年 | 12773篇 |
2008年 | 21969篇 |
2007年 | 23702篇 |
2006年 | 23584篇 |
2005年 | 23118篇 |
2004年 | 21771篇 |
2003年 | 21171篇 |
2002年 | 20546篇 |
2001年 | 37088篇 |
2000年 | 37762篇 |
1999年 | 31377篇 |
1998年 | 7558篇 |
1997年 | 6174篇 |
1996年 | 5368篇 |
1995年 | 4779篇 |
1994年 | 4252篇 |
1993年 | 3932篇 |
1992年 | 19619篇 |
1991年 | 18343篇 |
1990年 | 17521篇 |
1989年 | 17040篇 |
1988年 | 15302篇 |
1987年 | 14752篇 |
1986年 | 13604篇 |
1985年 | 12710篇 |
1984年 | 8728篇 |
1983年 | 7104篇 |
1982年 | 3736篇 |
1979年 | 7328篇 |
1978年 | 4688篇 |
1977年 | 4091篇 |
1975年 | 4075篇 |
1974年 | 4557篇 |
1973年 | 4293篇 |
1972年 | 4188篇 |
1971年 | 4098篇 |
1970年 | 3725篇 |
1969年 | 3696篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
C.T.-guided stereotactic destructive pain procedures; percutaneous cordotomy, trigeminal tractotomy-nucleotomy and extralemniscal myelotomy are presented. All procedures were applied in 32 cases without any mispuncture or complication. Advantages of C.T. guidance are direct visualization of target electrode relations, measurements of spinal cord diameters at the lesion site, and demonstration of spinal cord displacement during the procedure. 相似文献
992.
Hard metal asthma: cross immunological and respiratory reactivity between cobalt and nickel? 总被引:2,自引:1,他引:1 下载免费PDF全文
Eight asthmatic patients with hard metal asthma due to cobalt underwent bronchial provocation challenge with nickel sulphate. Seven patients developed a fall in FEV1 of 20% or more after inhaling nickel sulphate, four showing an immediate response and three a late response. Eight control subjects, including six asthmatic patients, with no history of hard metal exposure, showed no bronchoconstriction in response to a provocation challenge with nickel sulphate. Specific antibodies to nickel conjugated human serum albumin were present in four of the eight patients with sensitivity to cobalt conjugated human serum albumin but were absent from the serum of 60 unexposed asthmatic patients and 25 exposed symptom free workers. These results suggest that nickel as well as cobalt sensitivity plays a part in hard metal asthma. 相似文献
993.
More powerful procedures for multiple significance testing 总被引:27,自引:0,他引:27
The problem of multiple comparisons is discussed in the context of medical research. The need for more powerful procedures than classical multiple comparison procedures is indicated. To this end some new, general and simple procedures are discussed and demonstrated by two examples from the medical literature: the neuropsychologic effects of unidentified childhood exposure to lead, and the sleep patterns of sober chronic alcoholics. 相似文献
994.
Retinal pigmented epithelial cells are adherent at their basal surface to Bruch's membrane and at their apical surface to the neural retina. We examined the expression and distribution of two proteins that are found in regions of cell-matrix interaction, talin and integrin. Talin is a 235-kDa cytoplasmic protein that has been localized to regions of cell-substrate adhesion. It binds to both integrin, a transmembrane glycoprotein complex, and to vinculin, a cytoskeletal protein. In the present study, we produced a polyclonal antibody to chicken gizzard talin. Using this antibody we showed by western blot analysis that talin is expressed by RPE cells and is found in the triton-soluble fraction. Talin was shown to co-localize with integrin and vinculin in the basal region of chick RPE cells isolated from 18-day-old chick embryos. Neither talin nor integrin was found in the apical processes or in the zonula adherens. Antibodies to vinculin showed staining both in the apical and basal regions of the RPE cells. The localization of integrin, talin and vinculin along the basal membrane suggests that this complex is important in the attachment of the RPE cells to the basement membrane. The distribution of integrin and talin was examined in primary cultures of RPE cells grown on permeable filters. In these cells, a polarized distribution of integrin and talin was not observed. This may suggest that the neural retina may be important for maintaining the differentiated state of the RPE cells. 相似文献
995.
S. C. Chin C. Y. Chen C. C. Lee F. H. Chen K. W. Lee H. S. Hsiao R. A. Zimmerman 《Neuroradiology》1998,40(3):181-183
We report MRI and angiographic findings of an unusual giant arachnoid granulation in the left sigmoid sinus in a boy with
headache. Its signal intensity was lower than that of cerebral cortex on T1-weighted images and higher on T2 weighting, mimicking
dural sinus thrombosis.
Received: 17 February 1997 Accepted: 17 February 1997 相似文献
996.
Incidence of post-lumbar puncture syndrome reduced by reinserting the stylet: a randomized prospective study of 600 patients 总被引:1,自引:0,他引:1
The post-lumbar puncture syndrome (PLPS) can best be explained by prolonged spinal fluid leakage owing to delayed closure
of a dural defect. Its incidence after spinal anaesthesia is much lower than after diagnostic lumbar puncture (LP). This difference
could be caused by a strand of arachnoid, which might enter the needle with the outflowing cerebrospinal fluid (CSF) during
diagnostic LP and upon removal of the needle be threaded back through the dura to produce prolonged CSF leakage. To find a
technique that further reduces the incidence of PLPS, this hypothesis was tested by evaluating the effect that reinserting
the stylet before removing the needle had on the incidence of PLPS. By reinserting the stylet to the tip of the needle, the
hypothesized strand would be pushed out, thereby reducing the frequency of PLPS. Sprotte’s “atraumatic needle” (21 gauge)
was used for LP. A total of 600 patients participated in the prospective study. They were randomized into two groups and questioned
about their complaints every day for up to 7 days after the LP. All LPs were performed by two experienced neurologists (T.B.,
M.S.). In 300 patients, the stylet was reinserted to the tip of the needle; in the other 300 it was not reinserted. Whereas
49 of the 300 patients without reinsertion developed PLPS, only 15 of the 300 patients with reinsertion did. This significant
difference (16.3 vs 5.0%, P < 0.005, chi square test) supports our hypothesis. On the basis of our results, we recommend reinserting the stylet before
removing the needle in order to reduce the incidence of PLPS.
Received: 30 September 1997 Received in revised form: 9 March 1998 Accepted: 20 March 1998 相似文献
997.
Y. Mori M. Kubo H. Okumo Y. Kuroki 《Knee surgery, sports traumatology, arthroscopy》1995,3(3):167-172
The histological findings of the patellar cartilage were compared between cases of chondromalacia, which occurs predominantly in young persons (22 patients, average age 19.8 years) and cases of osteoarthritis, which is common among the elderly (21 patients, average age 65.4 years). The histological findings of cartilage in the chondromalacia were characterized by increased density and vigorous fibrous metaplasia of chondrocytes. These findings may be considered to represent a reactive change in the chondrocyte. Cartilage degeneration in osteoarthritis, by contrast, is regressive and presents a clearly different histological picture from that of chondromalacia patellae. We conclude that chondromalacia does not easily lead to osteoarthritis. On the other hand, the cartilage was characteristically softened, as observed by gross inspection, and showed rarefaction of the cartilage matrix. It should be noted that the change was not observed in aging, but showed a pattern of cartilage degeneration peculiar to young patients with chondromalacia patellae. 相似文献
998.
H. von Zitzewitz C. Düber P. Gutjahr W. Kersjes M. Thelen 《World journal of urology》1995,13(4):226-229
Summary During the past few years, a new tumor type has emerged in the pediatric and adolescent group of cancer patients, which has been designated malignant peripheral neuroectodermal tumor (MPNT). This tumor has some clinical and pathological signs in common with either soft-tissue sarcomas or classic Ewing's sarcoma, but is defined as a distinct entity because of its immunohistological characteristics. The tumor expresses neuronal markers, but the pattern varies: chromogranin, neuron-specific enolase, synaptophysin, protein S-100 and others. MPNT can occur in the urogenital region. The differential diagnosis on clinical grounds must include Ewing's and soft tissue sarcomas, and also Wilms' tumor and its variants. MPNT are often wide spread in the urogenital region when first diagnosed. Response to radiotherapy and combination chemotherapy is limited. Radical surgery is not always possible. The prognosis therefore remains rather poor at this time. A selection of MPNT patients is presented to demonstrate the various problems associated with this diagnosis. MRI and CT of all patients showed large tumors with direct infiltration of the surrounding structures. MRI is the best imaging modality for diagnosis and therapy monitoring in these tumors, because of its high soft-tissue contrast. 相似文献
999.
Flemming M. Nilsson Birgitte L. Hansen Christian Büchel Wagner F. Gattaz Jes Gerlach 《European archives of psychiatry and clinical neuroscience》1996,246(2):71-77
Digital movment analysis (DMA) is a new instrumental approach to assessing oral tardive dyskinesia (TD) by means of digital image processing of a video signal, tracking five paper dots placed around the patient's mouth. A total of 40 schizophrenic patients, 30 with and 10 without TD, were examined twice (with a 3-month interval) with this new device. The patients were further examined with two TD rating scales: the St. Hans Rating Scale for extrapyramidal syndromes (SHRS) and the Abnormal Involuntary Movement Scale (AIMS).The schizophrenic patients accepted the instrumental assessment without any anxiety or resistance. The internal relibility of the apparatus was high, with correlation coefficients of 0.80–0.99. The DMA TD values correlated with the SHRS and AIMS scores with correlation coefficients of 0.48–0.73 indicating an acceptable, although not strong, concurrent validity. Fluctuations occurred from the first to the second examination independent of medication. For these fluctuations no correlation was found between DMA values and rating scores. Finally, the DMA device was able to detect perioral tremor as a sign of parkinsonism.It has been concluded that DMA is a useful supplement to classical TD rating, although further validity evaluation is warranted. 相似文献
1000.