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   1285400篇
  免费   93489篇
  国内免费   1999篇
耳鼻咽喉   18344篇
儿科学   42570篇
妇产科学   38177篇
基础医学   188089篇
口腔科学   35521篇
临床医学   109116篇
内科学   252951篇
皮肤病学   26616篇
神经病学   100219篇
特种医学   50190篇
外国民族医学   366篇
外科学   198548篇
综合类   26772篇
现状与发展   1篇
一般理论   306篇
预防医学   93607篇
眼科学   29173篇
药学   98466篇
  1篇
中国医学   2509篇
肿瘤学   69346篇
  2018年   11955篇
  2015年   11772篇
  2014年   16254篇
  2013年   24665篇
  2012年   34013篇
  2011年   36420篇
  2010年   21467篇
  2009年   20219篇
  2008年   35394篇
  2007年   38348篇
  2006年   38881篇
  2005年   38180篇
  2004年   36744篇
  2003年   35709篇
  2002年   35271篇
  2001年   58352篇
  2000年   59861篇
  1999年   50932篇
  1998年   14328篇
  1997年   12908篇
  1996年   13168篇
  1995年   12429篇
  1994年   11825篇
  1993年   10925篇
  1992年   41131篇
  1991年   40521篇
  1990年   40084篇
  1989年   38873篇
  1988年   36248篇
  1987年   35502篇
  1986年   33843篇
  1985年   32276篇
  1984年   24034篇
  1983年   20897篇
  1982年   12438篇
  1981年   10981篇
  1980年   10246篇
  1979年   22726篇
  1978年   15949篇
  1977年   13783篇
  1976年   13026篇
  1975年   14252篇
  1974年   16765篇
  1973年   16143篇
  1972年   15380篇
  1971年   14292篇
  1970年   13264篇
  1969年   12779篇
  1968年   12022篇
  1967年   10521篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
122.
123.
124.
125.
A series of 1-alkyl-3,4-dihydroisoquinolines and the related 4-alkyl-1,2-dihydro-benzo[f]isoquinolines was synthesized using reactions of dialkylbenzylcarbinols and their naphthyl analogs with alkylcyanides. Experiments showed that 1-alkyl-6,7-dimethoxy-3,4-dihydroisoquinolines typically produce a hypotensive action, while the benzo-annelated structures usually exhibit a hypertensive effects. The most active compound decreases the arterial pressure in cats by 52 Torr and the effect lasts for about 4 hours. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 40, No. 3, pp. 15–17, March, 2006.  相似文献   
126.
BACKGROUND: To evaluate potential differences in light absorbing properties and stability of indocyanine green (ICG) adsorbed to the retinal surface and of ICG dissolved in water and balanced salt solution. METHODS: The retina of four human donor eyes was prepared by removing the vitreous from the retinal surface. The inner surface of the specimen was covered with two to three drops of a 0.05% or 0.15% ICG solution respectively. After 1 min, the dye was removed by careful irrigation using BSS plus. The retinal specimens were then investigated by diffuse reflection spectroscopy (UV/VIS/NIR Spectrometer Lambda 900/Perkin Elmer equipped with a PELA-1020 integrating sphere accessory) and their absorption evaluated by the Kubelka-Munk function. To control the sensitivity of the setting, diffuse reflectance spectra of ICG adsorbed to a cellulose membrane and Al(2)O(3) were measured. For comparison, absorption spectra of ICG dissolved in water and BSS plus solution were measured in relation to ICG concentration and time using an UV/VIS/NIR Spectrometer Lambda 900/Perkin Elmer. RESULTS: On the retinal surface, absorption spectra exhibited a steep increase of absorption beginning at 620 nm, with a maximum at 736 nm (0.05%) and a shoulder at 745 (0.15%) and a second maximum at approximately 800 nm for both concentrations. Repeated measurement of the retinal surface 13 days after the ICG exposure revealed no changes in the position of the maxima as compared to the initial measurements. Light absorbing properties of ICG on cellulose or Al(2)O(3) are similar to those seen on the retinal surface with respect to the pattern and location of absorption maxima. In contrast, ICG dissolved in water or BSS plus disclosed variations in absorption characteristics depending on dye concentration, solute and time of measurement. CONCLUSIONS: Absorption characteristics and stability of ICG bound to the retinal surface could be of relevance when investigating potential pathomechanisms of ICG related toxicity, which might be related not only to intraoperative but also to postoperative light exposure of patients after intravitreal use of ICG.  相似文献   
127.
French asthma patients may be supervised by general practitioners (GPs) and/or specialists. Therefore, this study examined asthma management in patients exclusively supervised by specialists (SPE), GPs, (GP) and both (GP+SPE group), and compared the findings. Asthma patients were consecutively recruited in 348 pharmacies. Each patient completed a questionnaire providing data on personal characteristics, asthma management, perception of disease and asthma supervision. Asthma control was measured using the Asthma Control Test. Questionnaires were linked to computerised records of medications which had been dispensed before inclusion in the study. From the 1,256 patients (mean age = 36.1 yrs, 54.3% females), 11.4, 36.6, and 52.0% were placed in the SPE, GP, and GP+SPE groups, respectively. During the previous 4 weeks, most patients in the SPE group were properly controlled (52.2 versus 26.4 and 21.5% in GP and GP+SPE groups, respectively). The SPE group made more use of fixed combinations of long-acting beta agonist and inhaled corticosteroid, while receiving less short-acting beta agonists, antitussives and antibiotics. Striking differences in symptoms and asthma management were observed according to the type of asthma supervision. The current results strongly support the need to improve the management of asthma in primary care, and the coordination of care between general practitioners and specialists.  相似文献   
128.
129.
130.
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