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   21845篇
  免费   1277篇
  国内免费   312篇
耳鼻咽喉   149篇
儿科学   1194篇
妇产科学   313篇
基础医学   2567篇
口腔科学   385篇
临床医学   1425篇
内科学   3553篇
皮肤病学   410篇
神经病学   1449篇
特种医学   765篇
外国民族医学   5篇
外科学   2863篇
综合类   1213篇
一般理论   1篇
预防医学   1575篇
眼科学   1084篇
药学   2229篇
  5篇
中国医学   525篇
肿瘤学   1724篇
  2023年   116篇
  2022年   305篇
  2021年   468篇
  2020年   333篇
  2019年   324篇
  2018年   396篇
  2017年   347篇
  2016年   388篇
  2015年   484篇
  2014年   672篇
  2013年   890篇
  2012年   1296篇
  2011年   1343篇
  2010年   850篇
  2009年   690篇
  2008年   1058篇
  2007年   1084篇
  2006年   987篇
  2005年   947篇
  2004年   815篇
  2003年   792篇
  2002年   716篇
  2001年   624篇
  2000年   640篇
  1999年   570篇
  1998年   242篇
  1997年   221篇
  1996年   195篇
  1995年   183篇
  1994年   144篇
  1993年   153篇
  1992年   361篇
  1991年   387篇
  1990年   348篇
  1989年   389篇
  1988年   293篇
  1987年   306篇
  1986年   244篇
  1985年   268篇
  1984年   231篇
  1983年   206篇
  1982年   128篇
  1981年   115篇
  1979年   187篇
  1978年   123篇
  1975年   134篇
  1974年   143篇
  1973年   136篇
  1972年   123篇
  1971年   142篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
102.
A patient with von Hippel Lindau disease, bilateral symmetric renal cell carcinoma and pulmonary metastases treated with immunotherapy is the subject of this study. A left kidney and tumour mass were removed and the tumour cells used to make an autologous tumour/bacille Calmette–Guérin (BCG) vaccine as part of the treatment protocol. The patient's pulmonary nodules responded, but the remaining renal nodule subsequently grew. Samples of both tumours were obtained allowing for an internally controlled evaluation of the histological and immunohistologic differences between a responding and non-responding tumour nodule after therapy. The immunotherapy protocol is designed to promote a T cell response to autologous tumour. Cellular infiltrates were demonstrated in both responding and non-responding nodules compared with the pretreatment tumour specimen, but the responding nodule contained proportionately more T cells as well as markedly increased numbers of plasma cells and granulocytes. This suggested that several arms of the immune system may have been operative in the responding nodule.  相似文献   
103.
In the buffalo the sympathetic ganglionic neurons were multipolar and contained finely granular or vesicular Nissl material and eccentric nuclei with more than one nucleolus. They measured (mean values) 23.62 X 14.30 mum in the cranial cervical ganglion, 22.51 X 13.58 mum in the vertebral ganglion, 25.25 X 15.75 mum in the cervicothoracic ganglion and 22.84 X 14.27 mum in the fourth thoracic ganglion. Their density values were 256 neurons/mm2 in the cranial cervical ganglion, 250 neurons/mm2 in the vertebral ganglion, 248 neurons/mm2 in the cervicothoracic ganglion and 252 neurons/mm2 in the fourth thoracic ganglion.  相似文献   
104.
Studies on the cellular mechanisms of working memory demonstrated that neurons in dorsolateral prefrontal cortex (dPFC) exhibit directionally tuned activity during an oculomotor delayed response. To determine the particular contributions of pyramidal cells and interneurons to spatial tuning in dPFC, we examined both individually and in pairs the tuning properties of regular-spiking (RS) and fast-spiking (FS) units that represent putative pyramidal cells and interneurons, respectively. Our main finding is that FS units possess spatially tuned sensory, motor, and delay activity (i. e., "memory fields") similar to those found in RS units. Furthermore, when recorded simultaneously at the same site, the majority of neighboring neurons, whether FS or RS, displayed isodirectional tuning, i.e., they shared very similar tuning angles for the sensory and delay phases of the task. As the trial entered the response phase of the task, many FS units shifted their direction of tuning and became cross-directional to adjacent RS units by the end of the trial. These results establish that a large part of inhibition in prefrontal cortex is spatially oriented rather than being untuned and simply regulating the threshold response of pyramidal cell output. Moreover, the isodirectional tuning between adjacent neurons supports a functional microcolumnar organization in dPFC for spatial memory fields similar to that found in other areas of cortex for sensory receptive fields.  相似文献   
105.
汉族男子体格及生殖器发育特点   总被引:1,自引:0,他引:1  
2411例汉族男性大学生体格和生殖器的测量结果如下:阴茎周径8.17±0.64cm,阴茎长度7.43±1.04cm,阴茎牵长13.33±1.19cm,右睾丸容积17.91±4.09ml,左睾丸容积17.83±4.05ml,身高171.07±5.66cm,体重58.43±7.75kg.北方学生体格和生殖器发育均优于南方.城、县、乡学生的生殖器发育无明显差异,但城市学生体格发育优于农村.16岁后阴茎、睾丸大小变化不大,但生殖器的发育可持续到30岁.  相似文献   
106.
We present a patient with 45,X/46,X,+r(X) mosaicism and lack of inactivation of either the normal or the ring X in the 46,X,+r(X) cells. The patient has mental retardation, syndactyly, minor facial anomalies, and a congenital heart defect. Although most patients with 45,X/46,X,+r(X) have the Ullrich-Turner syndrome, 2 previously described patients with this karyotype also had a distinct phenotype consisting of severe mental retardation, syndactyly, and abnormal face. The unusually severe phenotype in these patients was thought to be due to lack of X-inactivation of the ring X chromosome. The findings in our patient support this hypothesis.  相似文献   
107.
108.
We have studied three children with de novo terminal deletion of the long arm of chromosome 1 (46,XX,del(1)(q43)). They all have minor anomalies and neurological signs (severe psychomotor developmental delay, generalized hypotonia, and seizures) that have been described previously. In addition, all of these three patients have autistic-like behavior. They avoid eye contact, show no interest in people, express little emotion, and repeat stereotypic movements such as head nodding and purposeless finger manipulation. They also spend excessive time in making unusual sounds consisting of a high-pitched shrill cry with little intonation in infancy and a harsh, strained, and glottal stridency in later life. They make no labial, lingual, or nasal sounds. We suggest that these observations may be unique clinical manifestations of certain terminal 1q deletions.  相似文献   
109.
Because of its association with longevity and reduced incidence of coronary heart disease, it becomes important to find out how elevated HDL-cholesterol levels are determined. Analyses of family data from Cincinnati initially suggested environmental factors common to sibs; however, some form of dominant inheritance could not be ruled out. Reanalysis of the Cincinnati data by Iselius and Lalouel concluded against a major locus, but did identify three families as possibly segregating for a major locus. Analysis of an additional 26 kindreds from the same population in Cincinnati by Siervogel and associates concluded that a major gene could be causing familial aggregation of high density lipoprotein in white kindreds. In this analysis, we pooled all the white Cincinnati kindreds (n = 31), and investigated the familial transmission using complex segregation analysis. We failed to obtain clear evidence for major locus determination. Under the parsimonious hypothesis of no major locus, the polygenic heritability and common sibling environmental correlation were estimated as 0.531 and 0.263, respectively, consistent with other evidence.  相似文献   
110.
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