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   1643篇
  免费   72篇
  国内免费   10篇
耳鼻咽喉   6篇
儿科学   31篇
妇产科学   38篇
基础医学   271篇
口腔科学   22篇
临床医学   97篇
内科学   305篇
皮肤病学   64篇
神经病学   97篇
特种医学   25篇
外科学   279篇
综合类   8篇
预防医学   43篇
眼科学   165篇
药学   151篇
肿瘤学   123篇
  2023年   10篇
  2022年   13篇
  2021年   31篇
  2020年   16篇
  2019年   28篇
  2018年   28篇
  2017年   24篇
  2016年   22篇
  2015年   30篇
  2014年   35篇
  2013年   54篇
  2012年   98篇
  2011年   79篇
  2010年   61篇
  2009年   51篇
  2008年   89篇
  2007年   94篇
  2006年   87篇
  2005年   92篇
  2004年   80篇
  2003年   83篇
  2002年   91篇
  2001年   54篇
  2000年   64篇
  1999年   38篇
  1998年   18篇
  1997年   19篇
  1996年   14篇
  1995年   8篇
  1994年   18篇
  1993年   13篇
  1992年   25篇
  1991年   20篇
  1990年   28篇
  1989年   30篇
  1988年   28篇
  1987年   13篇
  1986年   12篇
  1985年   18篇
  1984年   15篇
  1983年   13篇
  1982年   9篇
  1981年   5篇
  1977年   4篇
  1975年   8篇
  1973年   4篇
  1972年   4篇
  1971年   8篇
  1967年   6篇
  1966年   7篇
排序方式: 共有1725条查询结果,搜索用时 15 毫秒
1.
A 54-year-old man presented with an 8-year history of a hard asymptomatic mass of the left submandibular area. Total excision of the left submandibular gland with radical neck dissection was performed under a diagnosis of a submandibular tumor, probably a malignant mixed tumor. The pathologic diagnosis was carcinosarcoma consisting of carcinomatous and sarcomatous elements. The epithelial component was composed of squamous cell carcinoma, undifferentiated carcinoma, and adenocarcinoma. The nonepithelial component was composed of chondrosarcoma, osteosarcoma, spindle cell sarcoma, rhabdomyosarcoma, and liposarcoma. In the central area of the tumor, a few remnants of benign pleomorphic adenoma were identifiable. The finding suggested that in our patient, the carcinosarcoma arose from a preexisting pleomorphic adenoma. In view of the expected aggressive nature of the tumor, the patient was treated with postoperative radiotherapy of 60 Gy total, in 30 daily fractions of 2 Gy, and chemotherapy. He currently remains well and free of disease 24 months after treatment.  相似文献   
2.
The medial globus pallidus plays a crucial role in generation of L‐DOPA‐induced dyskinesia in patients with Parkinson's disease. The 6‐hydroxydopamine‐lesioned rat exhibiting behavioral sensitization to L‐DOPA is one useful animal model for examining L‐DOPA‐induced dyskinesia. To determine neuropathological abnormality responsible for behavioral sensitization, the medial globus pallidus and the substantia nigra reticulata in 6‐hydroxydopamine‐lesioned rats treated with L‐DOPA were examined. Intermittent L‐DOPA treatment induced hypertrophy of the lesioned‐side of medial globus pallidus and substantia nigra reticulata of 6‐hydroxydopamine‐lesioned rats with behavioral sensitization to L‐DOPA. Additionally, coadministration of a 5‐HT1A receptor agonist, 8‐hydroxy‐2(di‐n‐propylamino)tetralin with L‐DOPA, alleviated the hypertrophy with improvement of the behavioral sensitization. These results suggest that hypertrophy of the medial globus pallidus and substantia nigra reticulata is associated with induction of behavioral sensitization to L‐DOPA in 6‐hydroxydopamine‐lesioned rats. Therefore, neuropathological changes corresponding to hypertrophy might underlie L‐DOPA‐induced dyskinesia in patients with Parkinson's disease.  相似文献   
3.
4.
The derivatives (2) of 3-(2,3-dihydro-2,2-dimethyl-3-oxo-5-benzofuranyl) acrylic acid (2b) were synthesized. The compounds (3a-g) in which bromo, methoxy, nitro, amino or acetamido group was introduced on the benzene ring of the derivatives (2) and the compounds (3h-k) in which acryloyl moiety was introduced on the 6- or 7-position of the benzofuranone skeleton also synthesized. Furthermore, propionic acid derivatives (4a-c), acetic acid derivatives (4d-g), formic acid derivatives (4h-k) and oxyacetic acid derivatives (5) were prepared by converting the acryloyl moiety of the derivatives (2) into propionyl, acetyl, formyl and oxyacetyl groups. These compounds were tested for antiulcer activities. Among these compounds, 1-[3-(2,3-dihydro-2,2-dimethyl-3-oxo-5-benzofuranyl)acryloyl]piperidine (2d) and 4-[3-(2,3-dihydro-2,2-dimethyl-3-oxo-5-benzofuranyl)acryloyl] morpholine (2g) were found to have stronger antiulcer activities.  相似文献   
5.
The authors prospectively studied changes in the optic disc and visual field associated with intraocular pressure (IOP) reduction for one year after surgery in 12 primary open-angle glaucoma eyes of 7 patients who underwent trabeculectomy because of elevated IOP despite maximum tolerable medical therapy and whose cup volume was demonstrated to be decreased at 3 or 6 months after surgery. Topographic parameters including C/D ratio, rim area and cup volume were determined by the Optic Nerve Head Analyzer plus (Rodenstock). The 30-2 central threshold field was obtained with a Humphrey Field Analyzer at the same time. Mean deviation (MD), corrected pattern standard deviation (CPSD) and total deviation (TD) were used to evaluate visual field changes. Significant improvement of C/D ratio, rim area and cup volume and significant IOP reduction were noted at 1 year after surgery as compared with preoperative baseline value (p less than 0.01). Also the MD was significantly decreased at 1 year after surgery, compared with the preoperative baseline value (p less than 0.05). There was a significant negative correlation between the preoperative MD and the percent change of the MD at 1 year after surgery (r = -0.80, p less than 0.01). Our results suggest that the decrease of optic disc cupping can persist over one year after surgery and that the early visual field defects in glaucoma eyes can gradually improve in association with the decrease of cupping.  相似文献   
6.
Leiomyoblastoma has been regarded as a neoplasm of smooth muscle origin. With recent progress in immunohistostaining techniques, many clinicopathological discrepancies have been pointed out about the origin of leiomyoblastoma. It has been claimed that gastrointestinal non-epithelial tumors should be regarded as stromal tumors in order to study their origin. In the present study, we performed various forms of immunohistostaining in seven cases of leiomyoblastoma to determine their origin. One case expressed desmine and muscle specific actin and was considered to be derived from smooth muscle. Four neoplasms expressed X-100 protein (two cases were also NSE positive) and were thought to be derived from the nerve. Two cases were of unknown derivation. These results suggest that the cells of leiomyoblastoma may arise from a primitive to totipotential cell of neural lineages that may anomalously express smooth muscle filaments.  相似文献   
7.
A patient with cerebral deep sinus thrombosis, which was not diagnosed on the first examination, is reported. A 46-year-old woman presented with headache and vomiting. Neurological examination and a brain computed tomography (CT) scan showed no obvious abnormal findings. The patient suffered disturbed consciousness on the day after the examination, and was admitted to our emergency centre. A CT scan and magnetic resonance imaging revealed an ischaemic lesion in the left basal ganglia, suggesting deep sinus occlusion. Anticoagulant therapy was administered. One day after admission, a CT scan showed a haematoma and severe brain swelling in the same region. Cerebral angiography demonstrated a straight sinus occlusion. Intracranial pressure was not controlled with hypothermia, and the patient died 25 days after admission. Review of the initial CT scan revealed subtle, early findings of deep venous thrombosis that were missed on first examination.  相似文献   
8.
Summary The participation of substance P in the noncholinergic contraction induced by transmural stimulation (TMS) of the carp intestinal bulb was examined. In the presence of atropine, substance P caused the contraction of carp intestinal bulb smooth muscle in a concentration dependent manner (1 nmol/1 – 1 mol/l). The EC50 value was 28 ± 7 nmol/l (n = 6). Substance P-induced desensitization (1 mol/l for 15 min), decreased the response to substance P and the atropine-resistant contraction induced by TMS (20 Hz) selectively. In contrast, in the absence of atropine, the contraction induced by TMS (20 Hz) was slightly attenuated with the substance P-induced desensitization. The acid extract obtained from the carp intestinal bulb contained a smooth muscle excitatory material whose pharmacological properties were consistent with those of substance P. The present results indicate that a substance P-like peptide is present in the carp intestinal bulb which is involved in the non-cholinergic contraction induced by TMS.Send offprint requests to T. Kitazawa at the above address  相似文献   
9.
Three cases of "spontaneous" pneumocephalus suspected to have resulted from aerobic bacteremia caused by Enterobacter cloacae, Escherichia coli, and Klebsiella aerogenes are reported. In two cases, the E. cloacae and K. aerogenes were isolated from the cerebrospinal fluid. These cases were characterized by a rapid accumulation of air, without niveau, in the subarachnoid space and ventricles.  相似文献   
10.
The effects of inhibitors of arachidonic acid metabolism andantioxidants on the rat liver tumor promotion activity of phenobarbital(PB) were assessed using the enzyme-altered focus as the end-pointlesion. Fischer 344 male rats were initiated with N-nitrosodiethylamine(200 mg/kg) and then divided into five groups placed on basaldiet, diet containing 0.05% PB, diet containing 0.05% PB plus0.75%, 1% or 1.5% levels of various inhibitors of arachidonicacid metabolism or antioxidants, or diet containing 1% or 1.5%inhibitors or antioxidants alone for 10 weeks, and then killed.-Bromo phenacyl bromide, an inhibitor of phospholipase A2 significantly inhibited the promotion activity of PB at dose levelsof 0.75% and 1.5%, reaching plateau at 0.75%. Both quercetin,an inhibitor of lipoxygenase, and morin, a dual inhibitor oflipoxygenase-cyclooxygenase, significantly reduced the promotionactivity of PB at the 1.5% but not 0.75% dose levels. Moreover,acetylsalicylic acid, an inhibitor of cyclooxygenase dose-dependentlyinhibited the promotion activity of PB. Among the antioxidantsinvestigated, vitamin E did not affect, but n-propyl gallateand ethoxyquin exerted a dose-dependent inhibition of PB promotion.These results are strongly suggestive of an involvement of phospholipaseA2 lipoxygenase and cyclooxygenase arachidonic acid metabolicpathways in the mechanisms underlying PB enhancement of hepatocarcinogenesis.  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