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   19071篇
  免费   1539篇
  国内免费   416篇
耳鼻咽喉   158篇
儿科学   193篇
妇产科学   136篇
基础医学   3271篇
口腔科学   558篇
临床医学   1815篇
内科学   2481篇
皮肤病学   807篇
神经病学   1343篇
特种医学   711篇
外国民族医学   3篇
外科学   1264篇
综合类   1941篇
现状与发展   7篇
预防医学   1860篇
眼科学   862篇
药学   2061篇
  22篇
中国医学   520篇
肿瘤学   1013篇
  2024年   59篇
  2023年   440篇
  2022年   498篇
  2021年   982篇
  2020年   882篇
  2019年   697篇
  2018年   650篇
  2017年   666篇
  2016年   670篇
  2015年   770篇
  2014年   1309篇
  2013年   1358篇
  2012年   1125篇
  2011年   1209篇
  2010年   904篇
  2009年   886篇
  2008年   896篇
  2007年   810篇
  2006年   647篇
  2005年   597篇
  2004年   543篇
  2003年   488篇
  2002年   401篇
  2001年   353篇
  2000年   258篇
  1999年   228篇
  1998年   238篇
  1997年   212篇
  1996年   173篇
  1995年   181篇
  1994年   166篇
  1993年   128篇
  1992年   140篇
  1991年   137篇
  1990年   126篇
  1989年   94篇
  1988年   113篇
  1987年   116篇
  1986年   78篇
  1985年   146篇
  1984年   132篇
  1983年   98篇
  1982年   107篇
  1981年   79篇
  1980年   75篇
  1979年   45篇
  1978年   28篇
  1977年   20篇
  1976年   23篇
  1974年   11篇
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
81.
合成了稀土(Ln)与2,2-联吡啶(L1)、1,10-菲罗啉(L2)的三元固态配合物。通过元素分析、IR谱、TGA谱和摩尔电导等对该系列配合物进行了表征,实测结果与通式LnL1L2Cl3·3H2O符合较好。抗菌试验表明,该系列配合物有较强的广谱抗菌作用。  相似文献   
82.
采用一种改进的方法,从100g猪心室肌中提取心肌肌球蛋白370mg,并进一步分离和纯化其亚基成分,分别得到肌球蛋白轻链24mg和重链210mg,核酸含量<1%,不含有肌动蛋白、原肌球蛋白、肌钙蛋白及其它杂蛋白;SDSPAGE显示,猪心肌球蛋白重链为200~220KD一条带,肌球蛋白轻链则为27kd、21.4kd、19kd三条带;纯化猪心肌球蛋白的Ca2+激活ATP酶活性为0.24μmolPi/(mg·min),但其分离后的亚基则无此活性。  相似文献   
83.
κ及λ轻链测定在多发性骨髓瘤诊断中的应用   总被引:2,自引:0,他引:2  
齐为民  郭力 《医学争鸣》1998,19(4):418-420
目的:寻求准确,可靠的免疫球蛋白及κ和λ轻链测定方法,提高多发性骨髓瘤分型和鉴别诊断水平。  相似文献   
84.
85.
Gallopamil is a calcium-channel antagonist with reported activity in experimental animals three to five times higher than that of verapamil. An automated high-performance liquid chromatographic (HPLC) method with fluorescence detection is described for the simultaneous determination of gallopamil and its metabolite norgallopamil in plasma. Gallopamil was well resolved from norgallopamil and other metabolites, allowing simultaneous quantitation of both drugs. The detection limit for both gallopamil and norgallopamil was 0.9 ng/ml. This method has been successfully used for the determination of gallopamil and norgallopamil following the administration of 25-, 37.5-, and 50-mg oral doses of drug.  相似文献   
86.
Summary In order to measure ejection fractions (EFs) from nuclear ventriculograms, we devised a semi-automated edge-detection technique based on a combination of inverse Fourier analysis and second-derivative techniques. Initial clinical studies showed that, for the left ventricle, our method gives EF values statistically identical with those obtained using a conventional isocontour technique. For the right ventricle, however, the values obtained using the two methods were somewhat more at variance. Despite requiring a longer processing time, the results obtained with our method are reproducible because less operator intervention is necessary.  相似文献   
87.
We previously reported the hyperosmolarity response (a decrease of the ocular standing potential by hyperosmolarity) as a new clinical test of the retinal pigment epithelium (RPE) activity. In the present study a hypertonic solution (Fructmanit, 1.4 × 103 m0sm/1) was intravenously injected for 20 min in proportion to a subject's total blood volume (TBV). At the injection speed of 5, 10, and 15% of the subjects' TBV per hour the mean amplitude of the hyperosmolarity response in normal subjects was 19.7, 30.1 and 36.4% respectively. The amplitude of the hyperosmolarity response depends on the logarithm of the dose of the hypertonic solution within the range of the dose tested.We previously found that hyperosmolarity suppresses the light rise. The present study investigated this suppressive effect in a quantitative manner. The light rise (a full-field illumination of 1.2 × 103 cdl/m2) was dose-dependently suppressed by Fructmanit. The mean of the light rise to dark trough ratio in normal subjects was 1.81 with no osmotic stress, and 1.64, 1.41 and 1.29 respectively at the injection speeds of 5, 10, and 15%. The suppression of the light rise by hyperosmolarity is compatible with the view that the hyperosmolarity response and the light rise share the basal membrane of the RPE as the main site of their generation.  相似文献   
88.
RFLP studies were done in 82 (75%) of all known hemophilia A families in the Finnish population (approximately 5 million). Two intragenic RFLPs (Bc1I/F8A, XbaI/p482.6) and two extragenic markers (TaqI/St14, Bg1II/DX13) were used. Among 263 females at risk, carriership could be evaluated with an intragenic marker in 47% and with an extragenic marker in 26%. In 27% of the females, carriership could be neither excluded nor confirmed; 68% of these females were relatives of an isolated patient. Eight recombinations between the factor VIII gene (F8C) and DXS52 (lod 25.02 at theta max 0.06), eight recombinations between F8C and DXS15 (lod 21.91 at theta max 0.05), and two recombinations between DXS52 and DXS15 (lod 33.56 at theta max 0.01) were found. Using multipoint linkage analysis, the most likely order of loci supported by the data was: F8C-DXS15-DXS52-DXS134. RFLP segregation analysis provides a highly useful method of carrier detection and prenatal diagnosis of hemophilia A, but its limitations must be carefully taken into account.  相似文献   
89.
Seven cases of carcinoma mimicking angiosarcoma occurring in skin (3 cases), breast (3) and lung (1) are described. The cutaneous, pulmonary and one of the breast carcinomas were poorly differentiated and squamous in type; the other two breast tumours were poorly differentiated ductal carcinomas with focal squamous differentiation. Histologically, the pseudoangiosarcomatous pattern was due to complex anastomosing channels and spaces lined by neoplastic cells. The spaces contained hyaluronic acid. The neoplastic cells exhibited cytokeratin positivity but yielded negative results with the endothelial cell markers, factor VIII-related antigen and CD 34 (QB-END/10). Two breast tumours showed binding of UEA-1. Ultrastructurally, unequivocal epithelial differentiation was demonstrated in six of the cases. Pathogenetically, these tumours appeared to be variants of acantholytic squamous cell carcinoma. Recognition of this unusual form of carcinoma is important, as an incorrect diagnosis of angiosarcoma may lead to inappropriate treatment and prognostication.  相似文献   
90.
A set-up for D.C. recordings of slow ocular potentials such as the c-wave of the electroretinogram (ERG) as well as the fast oscillation (FO), the light peak (LP) and the dark trough (DT) in both clinical and experimental work is described. It includes matched calomel half-cells connected by saline-agar bridges to a corneal contact lens on the eye and a reference chamber on the forehead, a low-drift differential-input D.C. amplifier, an A/D converter, a computer, a thermoprinter, a flexible disc memory, a plotter, and a device for light stimulation controlled by the computer.Examples of the usefulness of the set-up in clinical work are shown in the form of D.C. c-wave ERGs of normal subjects as well as of patients with vitelliform macular degeneration, choriocapillaris atrophy, and retinitis pigmentosa. The direct corneal recording of the FO and LP is demonstrated as well. The different origins of the standing potential (SP) of the eye, the ERG c-wave, the FO and the LP are reviewed briefly.  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