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   1324232篇
  免费   101777篇
  国内免费   4830篇
耳鼻咽喉   18957篇
儿科学   44992篇
妇产科学   35460篇
基础医学   186290篇
口腔科学   34160篇
临床医学   117169篇
内科学   263637篇
皮肤病学   28537篇
神经病学   102248篇
特种医学   52858篇
外国民族医学   676篇
外科学   200231篇
综合类   37348篇
现状与发展   9篇
一般理论   378篇
预防医学   99844篇
眼科学   29159篇
药学   100183篇
  57篇
中国医学   5135篇
肿瘤学   73511篇
  2019年   10166篇
  2018年   14204篇
  2017年   11281篇
  2016年   11993篇
  2015年   14240篇
  2014年   19689篇
  2013年   28877篇
  2012年   39904篇
  2011年   42411篇
  2010年   26167篇
  2009年   24663篇
  2008年   39996篇
  2007年   42284篇
  2006年   42461篇
  2005年   40847篇
  2004年   39458篇
  2003年   38154篇
  2002年   37224篇
  2001年   65065篇
  2000年   67329篇
  1999年   57017篇
  1998年   15519篇
  1997年   14137篇
  1996年   14489篇
  1995年   13692篇
  1994年   13006篇
  1993年   11909篇
  1992年   44675篇
  1991年   43571篇
  1990年   42269篇
  1989年   40158篇
  1988年   36948篇
  1987年   36269篇
  1986年   33638篇
  1985年   32302篇
  1984年   24155篇
  1983年   20273篇
  1982年   11727篇
  1981年   10693篇
  1979年   21342篇
  1978年   14821篇
  1977年   12532篇
  1976年   11693篇
  1975年   12623篇
  1974年   14662篇
  1973年   14118篇
  1972年   12946篇
  1971年   11729篇
  1970年   11051篇
  1969年   10024篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
The present study demonstrates that alcohol-induced memory impairment can be attenuated by pretreatment with an oral tryptophan supplementation. These results provide support for the role of a brain serotonin deficit in this impairment and highlight the impact a dietary manipulation can have on a complex behavioral process.  相似文献   
72.
The Dundee Memory Clinic was established in 1991. This paper reviews the diagnosis of the first 150 attenders and compares the findings with those of other memory clinics.  相似文献   
73.
Macrophage NRAMP1 and its role in resistance to microbial infections   总被引:12,自引:0,他引:12  
  相似文献   
74.
75.
76.
With pulsed X-ray cinematography we have analysed the angular excursions of the distal hindlimb joints (proximal interphalangeal, PIP; metatarsophalangeal, MTP; ankle) in cats walking on a treadmill. These distal joints transmit the body weight and the dynamic forces onto the ground. We have included the knee and hip joints in the analysis to relate the angular excursions of the proximal and distal joints and to verify the data previously obtained with external markers on the kinematics of the proximal joints. At the beginning of the stance phase the PIP joints flexed rapidly, the MTP joints extended slowly and the ankle and knee yielded under body weight. Whereas the PIP joints maintained a rather constant angular position of −75° throughout the stance phase, extension continued in the MTP joints from −230° at touch-down to −270° at the end of the stance phase. Around 50 ms before lift-off the MTP joints flexed rapidly. Early (−30 ms) after lift-off this flexion changed into a slow extension. The PIP joints extended swiftly at the stance-swing transition and moderately at the end of the swing phase. During the middle part of the swing phase they flexed slowly. Small rotatory movements around the long axis of the foot took place in the last 100 ms of the swing phase. The results of this study on the distal joints are discussed in relation to the placing of the paw, to the translation of forward propulsion into a MTP movement and to the lifting of the paw (conventionally described as toe curling). They show a differentiated mechanical interaction between the different distal limb joints during these different phases, which must be known in detail to interpret the corresponding electromyographic data and to understand how the hip is moved forward over the MTP joints which serve as the final pivot during stance.  相似文献   
77.
78.
The recently developed ELISA for the thrombin-antithrombin III complex (TAT) is a sensitive, specific, and simplified means of detecting intravascular coagulation. For further evaluation of the thrombogenicity of a polyamide (P) and a Hemophan (H) hollow-fibre dialyzer a cross-over study was done in ten stable patients on maintenance hemodialysis. At the same doses of heparin (mean bolus of 30 U/kg bw and maintenance doses of 86 U/kg bw), thrombin time and partial thromboplastin time were significantly lower using H. At the end of dialysis TAT was significantly higher in H (mean +/- SEM before HD 3.57 +/- .56, at 240 min 14.9 +/- 6.5 ng/ml, p less than 0.05, Wilcoxon-test) than in P (before HD 4.36 +/- .98, at 240 min 8.95 +/- 3.0 ng/ml, p less than 0.05 H 240 vs. P 240, Wilcoxon-test). Visible clotting was more pronounced in the H filter. Among other favourable features of blood compatibility the polyamide/polyvinylpyrrolidone copolymer with a hydrophilic/hydrophobic microdomain structure has less thrombogenicity. The modified cellulosic membrane H has advantages in complement activation and leukocyte depression, but thrombogenicity seems less favourable since the incorporated diethyl-amino-ethyl groups with their positive charge bind and inactivate negatively charged heparin.  相似文献   
79.
Although malignant fibrous histiocytoma (MFH) is the most common soft tissue sarcoma of adult life, it is fairly rare in the head and neck region (3-6%). Between 1983 and 1991 8 patients with MFH in the head and neck region have been observed and treated at the ENT-department of the University of Tübingen. 5 patients have been operated (laryngopharyngeal localization), 2 patients underwent irradiation (unresectable fast growing T4-tumors of the pharynx and thyroid) and one female patient refused further therapy after two resections elsewhere. Operated patients showed no evidence of disease 2-8 years after resection (all margins have been controlled histologically). Both irradiated patients died 4 respectively 2 months after full (70 Gy) and incomplete (17 Gy) radiotherapy without visible positive effects. Both patients developed pulmonary metastasis. Since MFH can grow in thin layers along musculaoponeurotic structures the exact size is not always demonstrable by ultrasound, CT or MR scans. Metastasis occur in up to 40%, preferentially in regionary lymph nodes, in lung, liver and skeletal system. These phenomenon requires a full pretherapeutic staging. Histologically MFH is sometimes hard to distinguish from other tumors as for example various sarcomas and pleomorphic carcinoma. Therefore, immunohistochemical (mesenchymal markers) and electron microscopical investigations are advised. Resection with exact histological controll of all margins is the therapy of choice. We experienced that laryngeal MFH (n = 3) can be resected without laryngectomy under certain circumstances. Although unsuccessfull in our two cases, according to the literature, radiotherapy should be administered in unresectable cases. Depending on localization and size of MFH long survival, in single cases healing, of this disease is possible by surgical treatment.  相似文献   
80.
Ethanol account for a significant fraction of the energy intake of persons consuming even moderate amounts of alcohol. A recent study has shown that although alcohol does not reveal itself as a layer floating at the top of a drink, metabolically it behaves more like oil than sugar.  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