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   26267篇
  免费   1341篇
  国内免费   174篇
耳鼻咽喉   199篇
儿科学   539篇
妇产科学   448篇
基础医学   2877篇
口腔科学   643篇
临床医学   2101篇
内科学   6868篇
皮肤病学   489篇
神经病学   2979篇
特种医学   794篇
外科学   4062篇
综合类   45篇
一般理论   5篇
预防医学   1104篇
眼科学   452篇
药学   1479篇
中国医学   30篇
肿瘤学   2668篇
  2024年   27篇
  2023年   172篇
  2022年   390篇
  2021年   756篇
  2020年   450篇
  2019年   622篇
  2018年   705篇
  2017年   560篇
  2016年   633篇
  2015年   695篇
  2014年   1020篇
  2013年   1277篇
  2012年   2014篇
  2011年   2006篇
  2010年   1172篇
  2009年   1077篇
  2008年   1768篇
  2007年   1825篇
  2006年   1686篇
  2005年   1670篇
  2004年   1658篇
  2003年   1367篇
  2002年   1345篇
  2001年   207篇
  2000年   138篇
  1999年   165篇
  1998年   254篇
  1997年   221篇
  1996年   213篇
  1995年   176篇
  1994年   135篇
  1993年   138篇
  1992年   127篇
  1991年   103篇
  1990年   108篇
  1989年   78篇
  1988年   77篇
  1987年   74篇
  1986年   73篇
  1985年   67篇
  1984年   83篇
  1983年   51篇
  1982年   48篇
  1981年   47篇
  1980年   35篇
  1979年   26篇
  1978年   22篇
  1977年   32篇
  1976年   23篇
  1974年   19篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Bilateral discoid medial menisci is an extremely rare condition of the knee and it can be associated to other pathological findings, including anterior portion cyst formation. We report on the clinical features, radiographic findings, treatment and results of one patient who presented a bilateral medial discoid meniscus combined with posterior portion cyst of the left knee. To the best of the author’s knowledge, this is the first case of bilateral medial discoid meniscus associated with posterior portion cyst formation.  相似文献   
82.
The immunohistochemical occurrence of the neurotrophin (NT) proteins nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-4 (NT-4), and neurotrophin-3 (NT-3) is shown in the pre-term newborn, infant, and adult human post-mortem cerebellum. The NT-like immunoreactive structures were unevenly distributed and showed regional differences among cerebellar lobules and folia. NGF-, NT-4-, and NT-3-positive neuronal perikarya were observed in all specimens examined. At variance with the other neurotrophins, the BDNF antiserum labelled neuronal cell bodies only in newborn life and infancy, as well as extensive nerve fibre systems, whose density increased with age. The NT-antibodies, tested by Western blot on human cerebellum homogenates, revealed immunoreactive bands corresponding to proteins of heterogenous molecular weight. The results obtained provide a first demonstration of the tissue localization of the NTs in the human cerebellum from perinatal to adult age, thus suggesting their involvement in the development, differentiation and maintenance of the cerebellar connectivity. Codistribution of the four NTs or sets of them was observed in cortical and deep nuclei neurons. Multiple trophic roles for NTs, encompassing the classic target-derived and local mechanisms of support, are envisaged as significant in development, differentiation, and maintenance of the human cerebellar connectivity.  相似文献   
83.
WAIS-R Verbal-Performance IQ difference scores for Ward's (1990) seven subtest short form and the complete WAIS-R were examined in patients with lateralized and diffuse lesions. For both versions, the expected Performance > Verbal pattern was observed in the right hemisphere lesion group, while no summary score differences were seen in the left hemisphere group. Verbal-Performance IQ discrepancies for the short form fell within +/- 5 points of the WAIS-R discrepancy scores in about 75%of the cases, regardless of lesion location. Statistically reliable IQ differences between the complete and abbreviated WAIS-R attained 66%, 91%, and 89% agreement for the left, right, and diffuse groups, respectively. The results support the clinical utility of the seven subtest short form.  相似文献   
84.
Two-step endoscopic resection of gastric leiomyomas   总被引:2,自引:0,他引:2  
Summary Our two-step technique for endoscopic treatment of gastric leiomyomas is illustrated. From January 1979 to June 1991, nine symptomatic patients with sessile leiomyomas of the stomach were treated at the Endoscopy Division of Istituto Nazionale Tumori, Milan.The diagnosis was achieved by means of endoscopic observation of the lesion and, when possible, by ultrasound endoscopy.This new technique consists of first removing superficial portion of the tumor by electrosurgical snare. Second, a cleavage plane is found within the proper muscle layer; the tumor is enucleated as much as possible by tightening the snare around it and creating a pseudo-stalk. No major complication occurred nor were any recurrences observed at 21.8 months in the 7/9 patients treated by endoscopy alone. Endoscopic therapy was performed on an outpatient basis and only large lesions required short hospitalization.  相似文献   
85.
Vincenzo De Giorgi  MD    Daniela Massi  MD    Elisa Trez  MD    Camilla Salvini  MD    Elena Quercioli  MD    Paolo Carli  MD 《Dermatologic surgery》2003,29(9):965-967
In dermoscopy, the correct recognition of the single parameters is fundamental to achieve great diagnostic accuracy, but the scarce morphologic expression of a parameter may lead to diagnostic errors. We report the case of a 27-year-old white man presenting a pigmented lesion of the back, which was present since puberty. Clinical examination revealed on the back the presence of a flat, gray-blue lesion and at the periphery a small dark-brown papule. An assessment of the lesion by means of dermoscopy was performed. The purpose of this report was to analyze the Blue Hue in dermoscopy with its histopathologic correlates, starting with the discussion of a clinical case.  相似文献   
86.
A girl with Diamond-Blackfan syndrome and hypopituitarism was suspected of having pituitary haemosiderosis because of the clinical picture and the long history of blood transfusions. On T1-weighted MR images the pituitary exhibited a markedly hypointense anterior lobe (mimicking the empty sella), suggesting iron deposition, while on T2W MRI the low signal of the pituitary was surrounded by the high signal of the CSF. MR may be considered the examination of choice for detecting iron overload in the pituitary. Received: 10 November 1997 Accepted: 21 November 1997  相似文献   
87.
Despite the potential utility of calcium supplementation and the availability of many calcium supplements in the market, there are few data concerning the absorbability of different calcium salts in different conditions. We have compared the acute metabolic responses following oral administration of calcium citrate (CC) or calcium gluconolactate and carbonate (CGC) given to 20 healthy perimenopausal women (aged 48–55 years). Ten women received two effervescent tablets of CC (each containing 500 mg of calcium) and 10 women received two effervescent tablets of CGC (each containing 500 mg of calcium). Before and on an hourly basis for 6 hours, serum total and ionized calcium, phosphate, and immunoreactive parathyroid hormone (iPTH) were measured. Urinary calcium and creatinine were also measured. Both calcium salts induced significant increase in serum total and ionized calcium and in urinary calcium excretion; they also significantly reduced circulating levels of iPTH. The analysis of ionized calcium and iPTH response curves to CC and CGC administration revealed a significantly greater bioavailability of CC compared with CGC. Our data suggest that CC could be prefered to CGC for its characteristics of absorbability and bioavailability.  相似文献   
88.
89.
90.
Summary (1) Longitudinal muscle strips from the human small intestine (jejunum/ileum) responded to electrical field stimulation (1–50 Hz) with frequency-related primary contractions which were largely atropine- (3 M) sensitive. When the tone was raised by addition of galanin (0.3 – 1 M), prostaglandin (PG) E2 (1–10 M) or neurokinin A (NKA, 0.1 M), a frequency-related relaxation was evident which was potentiated by atropine. All the responses to field stimulation were abolished by tetrodotoxin (1 M), thus indicating their neural origin. (2) The atropine-sensitive primary contraction to field stimulation was virtually abolished by omega conotoxin fraction GVIA (CTX, 0.1–0.3 M) while the relaxations were CTX-resistant. The field stimulation-induced relaxations, which were observed in the presence of atropine and guanethidine (3 M), were also unaffected by apamin (0.1 M). (3) NKA and substance P (SP) produced a concentration- (1 nM–1 M for both peptides) related contraction, NKA being about 53 times more potent than SP. [Pro9]SP sulphone and [MePhe7]-NKB, selective agonists of the NK-1 and NK-3 receptor, respectively, were barely effective. On the other hand, [\Ala8]NKA(4–10), a selective NK-2 receptor agonist, had a potent contractile activity, similar to that of NKA. (4) Galanin (1 nM–1M) produced an atropine- and tetrodotoxin-resistant concentration-related contraction of longitudinal muscle of human isolated small intestine. The response to galanin did not show any sign of fading and was particularly suitable to study the evoked relaxations. (5) Calcitonin gene-related peptide (CGRP) (10–100 nM) consistently inhibited the nerve-mediated contractions of strips from the ileum while the effect on the jejunum was less pronounced. Vasoactive intestinal polypeptide (VIP, 0.1–1 M) inhibited nerve-mediated contractions both in the ileum and the jejunum. (6) These experiments indicate that both cholinergic excitatory and non-adrenergic non-cholinergic nerves affect motility of the longitudinal muscle of the human small intestine. Furthermore, several neuropeptides produce potent motor effects, the contractile response to tachykinins being apparently mediated by activation of NK-2 receptors.  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