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   23540篇
  免费   457篇
  国内免费   45篇
耳鼻咽喉   694篇
儿科学   497篇
妇产科学   2051篇
基础医学   3311篇
口腔科学   989篇
临床医学   803篇
内科学   4044篇
皮肤病学   775篇
神经病学   2100篇
特种医学   330篇
外科学   2344篇
综合类   103篇
一般理论   1篇
预防医学   1604篇
眼科学   1056篇
药学   2753篇
中国医学   29篇
肿瘤学   558篇
  2022年   261篇
  2021年   470篇
  2020年   131篇
  2019年   222篇
  2018年   400篇
  2017年   266篇
  2016年   288篇
  2015年   328篇
  2014年   507篇
  2013年   673篇
  2012年   863篇
  2011年   985篇
  2010年   502篇
  2009年   286篇
  2008年   605篇
  2007年   799篇
  2006年   900篇
  2005年   818篇
  2004年   913篇
  2003年   899篇
  2002年   760篇
  2001年   683篇
  2000年   675篇
  1999年   567篇
  1998年   184篇
  1992年   372篇
  1991年   324篇
  1990年   362篇
  1989年   409篇
  1988年   474篇
  1987年   452篇
  1986年   464篇
  1985年   434篇
  1984年   351篇
  1983年   260篇
  1979年   528篇
  1978年   317篇
  1977年   257篇
  1976年   247篇
  1975年   344篇
  1974年   513篇
  1973年   515篇
  1972年   431篇
  1971年   409篇
  1970年   388篇
  1969年   409篇
  1968年   355篇
  1967年   274篇
  1966年   291篇
  1965年   176篇
排序方式: 共有10000条查询结果,搜索用时 27 毫秒
81.
82.
Two groups of proteins are present in the vitreous: collagen and non-collagen, deriving probably from the blood serum. The authors examined the proteolytic activity against haemoglobin in the course of some ocular pathological conditions. It was demonstrated that the vitreous digests haemoglobin in the acid division of pH (optimum--3.0-4.5) with various activity dependent on the pathological condition of the eye.  相似文献   
83.
Two cases of sarcoidosis located outside the lungs are reported. In both cases the symptoms of the sicca syndrome were in the foreground. In the first case other clinical manifestations included mediastinal and retroperitoneal lymphadenopathy, and lacrimal gland impairment. In the other case the symptoms of the sicca syndrome were associated with polyneuropathy and maculopapular skin rash. The diagnosis of sarcoidosis was confirmed by histological examination of a biopsy specimen of lower lip mucosa in the first case, and biopsy of skin lesion in the second case. Abnormal results of laboratory tests included only raised erythrocyte sedimentation rate, in both cases and presence of circulating immune complexes in one case. Serological tests failed to demonstrate the presence of rheumatoid factor, antinuclear and anti-ds DNA antibodies. No decrease was observed also in the haemolytic activity of the complement, and cryoglobulins were absent. Regression of clinical signs was obtained in both cases after treatment with glucocorticosteroids.  相似文献   
84.
Administration of kainic acid (15 mg/kg, i.p.) or pentetrazole (75 mg/kg, i.p.) to rats evoked recurrent limbic or tonic-clonic seizures, respectively. Radioimmunoassay showed that the level of alpha-neoendorphin (prodynorphin-derived peptide) in the hippocampus was decreased after 3 h (by c. 60%) and 72 h (by c. 40%), but was not changed after 24 h following kainic acid administration. The basal release of alpha-neoendorphin from hippocampal slices of kainic acid-treated rats was decreased after 3, 24 and 72 h following the drug injection by c. 50%. The K(+)-stimulated release was decreased after 3 and 24 h (by c. 300 and 200%, respectively) and was back to the control level after 72 h. An in situ hybridization study showed that kainic acid strongly enhanced the prodynorphin messenger RNA levels in the dentate gyrus after 3 and 24 h (by c. 200%), whereas after 72 h it tended to decrease. Twenty four hours after pentetrazole injection the hippocampal level of alpha-neoendorphin was elevated (by c. 33%) and remained unchanged after 3 and 72 h. No significant changes in the basal or K(+)-stimulated alpha-neoendorphin release from hippocampal slices of pentetrazole-treated rats were found at any time points measured. Three and 24 h after pentetrazole administration the level of prodynorphin mRNA in the dentate gyrus was slightly decreased (by c. 30%), but was back to the control values after 72 h. Hence seizure-related changes in hippocampal prodynorphin neuron activity seem to depend on the experimental model of epilepsy.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
85.
The authors present the results of investigations performed in 28 right-handed, normally seeing persons divided into 2 groups: 15 of them were in productive age and 13 in older age. The authors compared the dynamics of the behaviour of the visual functions in dependence on the age of the subjects and the stay in the glow and sodium light. No adverse influence of the sodium light on the hand localization could be detected, instead it seems that it negatively influenced the selective reaction in older productive persons in the sense of an increased number of faults.  相似文献   
86.
Transient osteoporosis of the hip is an uncommon disorder of unclear etiology. It is often confused with other diagnosis including osteonecrosis of the femoral head. Authors describe a case of transient osteoporosis of the hip of 32 years woman. The symptoms occurred in third trimester of pregnancy. The primary symptoms were right hip pain and decreased range of motion of the right hip. In diagnostic process helpful were clinical examination, X-ray, ultrasonography, MRI and microscopic examination. As a treatment authors used walking on crutches, calcitonin and calcium preparate. After a few months remission of symptoms and normalization in accessory investigations were obtained.  相似文献   
87.
The spectrometric analysis of extracts from tobacco and tobacco smoke revealed the presence of pentobarbital in the analyzed substances. Tobacco samples and tobacco smoke were extracted with chloroform, determinations were performed with the Perkin-Elmer Autosystem XL system, on a Turbo Mass spectrometer. Subject to analysis were 4 cigarette brands manufactured in Poland and raw, unprocessed tobacco. The presence of pentobarbital in the analyzed samples was confirmed by the analysis of the mass spectrum of the substance, as well as by comparison of retention time with standard of pentobarbital. The determined pentobarbital concentrations in tobacco amounted to 3-6 microg/cigarette, and in tobacco smoke they were approximately 45% lower. In case of tobacco extracts it can with high probability be excluded that pentobarbital is synthesized during chromatographical analysis. The presence of pentobarbital in tobacco is thus beyond question.  相似文献   
88.
The aim of this study was to evaluate the influence of female sex hormones on phenazone pharmacokinetics using as an experimental model female rabbits after a bilateral ovariectomy. Eighteen female rabbits divided into two groups: control animals and experimental rabbits, that underwent ovariectomy, were used in the study. Pharmacokinetic assays were performed in all animals: prior to the study, after 1 month and after 2 months. Blood was sampled within 24 hours after intragastric administration of phenazone at a dose 50 mg/kg b.w. Two compartment open model was used for calculations. Significant increase in AUC and prolongation of phenazone halflife as well as a decrease in the total body clearance were noted. The study demonstrated the possible inhibition of the microsomal mixed-function oxidase system by oestrogens.  相似文献   
89.
90.
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