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   8857篇
  免费   790篇
  国内免费   21篇
耳鼻咽喉   23篇
儿科学   404篇
妇产科学   177篇
基础医学   1408篇
口腔科学   322篇
临床医学   957篇
内科学   1570篇
皮肤病学   149篇
神经病学   1057篇
特种医学   208篇
外科学   991篇
综合类   195篇
一般理论   10篇
预防医学   777篇
眼科学   111篇
药学   708篇
中国医学   30篇
肿瘤学   571篇
  2021年   131篇
  2020年   96篇
  2019年   141篇
  2018年   148篇
  2017年   117篇
  2016年   129篇
  2015年   129篇
  2014年   183篇
  2013年   287篇
  2012年   432篇
  2011年   399篇
  2010年   264篇
  2009年   201篇
  2008年   412篇
  2007年   374篇
  2006年   372篇
  2005年   367篇
  2004年   336篇
  2003年   349篇
  2002年   319篇
  2001年   283篇
  2000年   280篇
  1999年   234篇
  1998年   102篇
  1997年   86篇
  1996年   68篇
  1995年   86篇
  1994年   66篇
  1993年   66篇
  1992年   180篇
  1991年   214篇
  1990年   157篇
  1989年   196篇
  1988年   210篇
  1987年   249篇
  1986年   196篇
  1985年   230篇
  1984年   136篇
  1983年   94篇
  1982年   75篇
  1981年   78篇
  1980年   65篇
  1979年   105篇
  1978年   107篇
  1977年   89篇
  1976年   64篇
  1975年   73篇
  1974年   77篇
  1973年   72篇
  1972年   72篇
排序方式: 共有9668条查询结果,搜索用时 46 毫秒
91.
Direct chromosome preparations of neonatal cord blood provides the unique opportunity for rapid chromosome analysis (turnaround time; 6 hr), without the necessity of bone marrow aspiration. Based on 42 samples we confirm the finding of Garnham and Sutherland [1987] for suitability of cord blood for direct chromosome preparation. Procedural modifications are provided for higher yield of cells for chromosome analysis. The procedure may well be of major significance for rapid diagnosis of neonates who suffer from aneusomy.  相似文献   
92.
Whole-mount airway preparations isolated from the lungs of mice treated by intraperitoneal injection of naphthalene and allowed to recover for 5 days were examined for the distribution and abundance of solitary pulmonary neuroendocrine cells (PNECs) and neuroepithelial bodies (NEBs) along the main axial pathway of the right middle lobe. Sham mice treated with corn oil vehicle were examined in a similar manner. An antibody to calcitonin gene-related peptide, a neuroendocrine cell marker, was used to identify the location, size, and number of PNECs and NEBs in the airways. After naphthalene treatment and epithelial repair, NEBs were significantly increased along the walls of the airways as well as on branch point ridges. The surface area covered by NEBs composed of 20 or fewer PNECs was significantly enlarged after naphthalene treatment compared with control NEBs of an equivalent cell number. The PNEC number per square millimeter was also increased more than threefold above control values after naphthalene treatment. These findings provide further support for a key role of neuroendocrine cells in the reparative process of airway epithelial cell renewal after injury.  相似文献   
93.
94.
J G Hall  J Hopkins  J Reynolds 《Immunology》1980,39(2):141-149
Efferent lymph from nodes regional to areas of skin that had been treated with solutions of oxazolone in acetone was collected from unanaesthetized sheep. The application of 5% solutions of oxazolone to unsensitized sheep caused no signs of acute inflammation or ''shut-down'' of lymphocyte traffic; none the less, normal immune responses ensued so that immunoblasts, some containing immunoglobulin, were discharged into the lymph together with specific humoral antibodies. When previously sensitized sheep were challenged with 2.5% solutions of oxazolone the vigorous secondary responses were heralded by Arthus reactions, induced presumably by pre-existing antibodies, which were mainly of the IgG class. A similar sequence of events occurred in a thymus-deprived sheep which had undergone intra-uterine thymectomy at 60 days of gestation. Repeated applications of oxazolone to normal sheep did not exhaust or inhibit the characteristic changes in the flow and composition of the lymph. When immunoblasts from efferent lymph were radiolabeled with 125I-UdR and returned intravenously to the sheep they showed no significant tendency to localize either specifically or non-specifically in areas of skin that had been treated with contact-sensitizing chemicals.  相似文献   
95.
Three judges were trained to evaluate the frequency, intensity, and duration of aggressive responses in rats. Intrajudge and interjudge reliability ranged from .84 to .99. Correlation coefficients between frequency, intensity, and duration of aggressive responses ranged from .89 to .99. All three measures were found to be highly reliable methods of measuring aggression.  相似文献   
96.
Expression of clinical findings of Waardenburg syndrome type 1 (WS1) and type 2 (WS2) is extremely variable. Using our collection of 26 WS1 and 8 WS2 families, we analyzed the occurrence, severity, and symmetry of clinical manifestations associated with WS. We found significant differences between WS1 and WS2 in deafness, and in pigmentary and craniofacial anomalies. Factor analysis was used to identify manifestations which covaried, resulting in 2 orthogonal factors. Since mean factor scores were found to differ when compared between WS1 and WS2, we suggest that these factors could be useful in distinguishing WS types. We found that the WS gene was transmitted from mothers more often than from fathers. We also extensively examined the W-Index, a continuous measure of dystopia canthorum. Our data suggest that use of the W-Index to discriminate between affected WS1 and WS2 individuals may be problematic since 1) ranges of W-Index scores of affected and unaffected individuals over-lapped considerably within both WS1 and WS2, and 2) a considerable number of both affected and unaffected WS2 individuals exhibited W-index scores consistent with dystopia canthorum. Misclassification of families may have implications for risk assessment of deafness, since WS2 families have been reported to have greater incidence of deafness, as confirmed in our study. © 1995 Wiley-Liss, Inc.  相似文献   
97.
Association of Streptococcus bovis Bacteremia with Bowel Disease   总被引:4,自引:5,他引:4       下载免费PDF全文
We reviewed the medical records of 19 patients who had Streptococcus bovis bacteremia. Eight patients had diverticulosis, four had benign adenomatous colonic polyps, and three had adenocarcinomas of the gastrointestinal tract. Laboratory workers and clinicians should be aware of the association of S. bovis bacteremia and gastrointestinal disease.  相似文献   
98.
Sclerochoroidal calcification is an uncommon condition. Metabolic evaluation and clinical examination are important to exclude associated systemic conditions such as the Bartter and Gitelman syndromes. It has been suggested that the lesions seen in sclerochoroidal calcification are calcium pyrophosphate dihydrate crystals. This report describes the first documented case in the UK of sclerochoroidal calcification associated with Gitelman syndrome and calcium pyrophosphate dihydrate deposition.  相似文献   
99.
Porphyromonas gingivalis is a bacterial pathogen that produces the polyproteins RgpA and Kgp, which are proteolytically processed into proteinases and adhesins. We have demonstrated that the RgpA and Kgp proteinases and adhesins are C terminally processed by carboxypeptidase CPG70 by sequencing C-terminal peptides from both the wild type and an isogenic CPG70 mutant, using ion trap mass spectrometry.  相似文献   
100.
The effects of intra-arterial injections and infusions of epinephrine, norepinephrine, and isoproterenol on gastric blood flow were studied in anesthetized baboons. Blood flow was measured electromagnetically before and after adrenergic blockade. The results for injected epinephrine and norepinephrine indicate these agents to be pure vasoconstrictors in the primate gastric circulation, and this response is attenuated by alpha-adrenergic blockade with phenoxybenzamine. Isoproterenol is a pure vasodilator, and its response is attenuated following beta-adrenergic blockade with propranolol. Intra-arterial infusions of epinephrine and norepinephrine (.05 mug kg-1 min-1) resulted in sustained vasoconstriction with no evidence of autoregulatory escape and no postinfusion "over-shoot." This study suggests that epinephrine and norepinephrine might provide alternatives to vasopressin as a vasoconstrictor for the control of upper gastrointestinal bleeding.  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