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   9610篇
  免费   485篇
  国内免费   38篇
耳鼻咽喉   131篇
儿科学   171篇
妇产科学   95篇
基础医学   1163篇
口腔科学   216篇
临床医学   635篇
内科学   2563篇
皮肤病学   103篇
神经病学   920篇
特种医学   264篇
外科学   1826篇
综合类   43篇
预防医学   334篇
眼科学   109篇
药学   614篇
中国医学   20篇
肿瘤学   926篇
  2022年   114篇
  2021年   184篇
  2020年   109篇
  2019年   152篇
  2018年   186篇
  2017年   134篇
  2016年   163篇
  2015年   173篇
  2014年   242篇
  2013年   259篇
  2012年   411篇
  2011年   455篇
  2010年   256篇
  2009年   197篇
  2008年   378篇
  2007年   428篇
  2006年   383篇
  2005年   443篇
  2004年   373篇
  2003年   366篇
  2002年   400篇
  2001年   382篇
  2000年   422篇
  1999年   325篇
  1998年   103篇
  1997年   88篇
  1996年   89篇
  1995年   55篇
  1994年   59篇
  1993年   58篇
  1992年   236篇
  1991年   227篇
  1990年   191篇
  1989年   235篇
  1988年   177篇
  1987年   194篇
  1986年   174篇
  1985年   165篇
  1984年   105篇
  1983年   94篇
  1979年   102篇
  1978年   61篇
  1977年   48篇
  1974年   48篇
  1973年   53篇
  1972年   66篇
  1971年   47篇
  1970年   51篇
  1969年   55篇
  1968年   55篇
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
31.
Histamine (HA) is the most important mediator of nasal allergy and nasal hypersensitivity. To investigate HA metabolism, HA content and activities of its synthetic enzyme, histidine decarboxylase (HDC) and degrading enzymes, histamine-N-methyltransferase (HMT) and diamine oxidase (DAO) in nasal mucosa of human and toluene diisocyanate (TDI) sensitized guinea-pigs were measured. In human nasal mucosa and nasal polyps, HA content and HDC activity were 80-200 nmol/g tissue, 20-30 fmol/min/mg protein respectively. Among two degrading enzymes, HMT activity was 20-200 times higher than that of DAO. In the nasal mucosa of guinea-pigs, HA content was significantly increased by TDI sensitization, and was decreased immediately after TDI provocation. In 24 hours after provocation, HA content recovered to 80% of pre-provocation level. HDC activity increased by TDI sensitization significantly. Though HMT activity increased slightly by TDI sensitization and provocation, DAO activity was unchanged. The data suggest that, increase in turnover rate of HA is present in allergic nasal mucosa.  相似文献   
32.
33.
A 6 month-old male infant (weight: 4.5 kg) with congenital aortic stenosis underwent aortic valve replacement with a pulmonary autograft (Ross procedure). The right ventricular outflow tract (RVOT) was reconstructed with a polytetrafluoroethylene (PTFE)-valved equine pericardial conduit. At the age of 5, re-RVOT reconstruction with an equine pericardial patch bearing a PTFE monocusp was required because of severe pulmonary stenosis resistant to 2 attempts of percutaneous transluminal pulmonary valvotomy. Currently, at the age of 8, the degree of aortic regurgitation is trivial and the pulmonary autograft is free of functional deterioration despite somatic growth.  相似文献   
34.
To find antiviral agents, various sulfonamidobenzophenone oximes (II) were synthesized from the appropriate m-sulfonamidobenzophenones by hydroxylamine reaction. The reaction products were generally obtained as syn/anti mixtures which were separable by fractional crystallization. The anti isomer had more potent antipoliovirus activity than the syn isomer. Various sulfonamidobenzamides (III) which were structurally related to II were synthesized by the reactions of amino-substituted benzamides with sulfuryl chloride or amines with (aminosulfonyl)benzoyl chloride. Antiviral activity was examined by the plaque-inhibition test. Compounds 5, 36, and 69 exhibited strong antipicornavirus activity. The structure-activity relationships are discussed.  相似文献   
35.
S Kikuchi  O Wada  H Tenjin  Y Inaba 《Gan no rinsho》1989,35(2):202-206
From an observation of personnel we expect epidemiological studies make mass-screening of stomach cancer more efficient and suppose they should be done as to following aspects: (1) To decide the most efficient interval of mass-screening, investigating the frequency distribution of "Saving Duration" on many stomach cancers that is the duration when a stomach cancer is both detectably by screening and curable. (2) To decide who should undergo stomach examination quantifying cancer-risks of individuals with the use of epidemiological results. (3) To make epidemiological studies more sensitive and useful, classifying stomach cancers by microscopic pathological type, macroscopic one or "Saving Duration". (4) To settle a statistical standard of epidemiological results which is demanded for them to be useful in mass-screening.  相似文献   
36.
Argyrophil cells and melanocytes in esophageal mucosa   总被引:5,自引:0,他引:5  
  相似文献   
37.
We examined the possibility that lumbar skin warming can increase gastrointestinal motility by investigating the electrogastrogram (EGG), blood pressure, and heart rate with psychometric ratings in healthy humans. Scores of mood state profiles showed that lumbar skin warming (42 degrees C, 20 min) decreased tension-anxiety, depression, anger-hostility, fatigue, and confusion of the participants. A multiple bandpass filter analysis of EGGs showed that a postural transition from orthostatic to supine for measurement caused an increase in dominant frequency of 25-29% towards the frequencies of the normal interdigestive migrating motor complex (IMC). The spectral power of the IMC band, 2.55-3.05 cycles/min, was increased by 20 min-warming, reflecting the increase in gastric contractility. No increase in the spectral power was observed in the time-matched control group without skin warming. Therefore, an increase in contractility is a characteristic of lumbar skin warming. The systolic blood pressure increased by 15% during warm stimulation. Interbeat intervals were not influenced by warm stimulation. An analysis of interbeat intervals by a fast Fourier transform method showed that the cardiac sympathetic and parasympathetic nerves did not play a major role in raising the blood pressure. Vasoconstriction of the mesenteric artery was therefore considered to cause a blood pressure increase during warming. It is hypothesized that vasoconstriction of the visceral arteries by lumbar skin warming increases the blood pressure and gastrointestinal contractility.  相似文献   
38.
E Wada  A Urisu  Y Kondo  F Horiba  M Tsuruta  T Yasaki  S Masuda  K Yamada  T Kozawa  Y Hida 《Arerugī》1991,40(12):1493-1499
IgE-mediated mechanisms are important in immediate hypersensitive reactions (IHR) to buckwheat. However, a part of subjects with high IgE for buckwheat show no IHR to buckwheat ingestion. Inspite of cross-allergenicity between buckwheat and rice, rice ingestion rarely induces IHR even in subjects with high IgE for rice unlike buckwheat-induced IHR. We speculated that there were some relationships between the presence of IHR to buckwheat and recognition of cross-allergenic determinants on buckwheat components with rice components. We examined IgE-RAST for rice in 58 subjects with positive IgE-RAST for buckwheat. IgE-RAST for Dermatophagoides pteronyssinus (Dp), egg white and cow's milk as unrelated antigens with rice were also assessed for a comparison. Subjects (n = 33) without IHR to buckwheat showed higher IgE-RAST values for rice than those (n = 25) with IHR, whereas there were no differences in IgE-RAST values for Dp, egg white and cow's milk between two groups with and without IHR. IgE-RAST values for buckwheat showed significant close correlations to those for rice in subjects without IHR to buckwheat but not in those with IHR. There were no significant correlations between IgE-RAST values for buckwheat and for Dp, egg white or cow's milk in both groups with and without IHR. These results suggested that the IgE from subjects without IHR to buckwheat recognized cross-allergenic determinants with rice on the buckwheat components.  相似文献   
39.
40.
Percutaneous aspiration biopsy of the pancreas using a heparinized 22-gauge fine needle was performed under ultrasonic guidance in five patients with benign pancreatic diseases and in 18 patients with pancreatic cancer. Using a heparinized needle and syringe, it was possible to make good smears containing abundant tumor cells and to obtain small tissue specimens. Using egg albumin as binding material, a new cell-block technic was developed to conveniently obtain histologic specimens. In this way, a correct diagnosis was made cytologically in all 23 patients suspected of having a pancreatic malignancy. Histologic specimens were obtained in 22 (95.6%) our of 23 patients. A correct diagnosis was established histologically in all patients from whom histologic materials were obtained. This procedure thus has proved a very reliable method for diagnosing pancreatic cancer.  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