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   241794篇
  免费   11178篇
  国内免费   402篇
耳鼻咽喉   3198篇
儿科学   7464篇
妇产科学   4990篇
基础医学   34972篇
口腔科学   5498篇
临床医学   18879篇
内科学   52759篇
皮肤病学   6440篇
神经病学   21358篇
特种医学   7341篇
外国民族医学   101篇
外科学   30697篇
综合类   997篇
一般理论   72篇
预防医学   21835篇
眼科学   4770篇
药学   16878篇
中国医学   713篇
肿瘤学   14412篇
  2023年   1245篇
  2022年   856篇
  2021年   3462篇
  2020年   2058篇
  2019年   3892篇
  2018年   7461篇
  2017年   4912篇
  2016年   4907篇
  2015年   5497篇
  2014年   5715篇
  2013年   9307篇
  2012年   16163篇
  2011年   16119篇
  2010年   8056篇
  2009年   6029篇
  2008年   13948篇
  2007年   14933篇
  2006年   13821篇
  2005年   13712篇
  2004年   12918篇
  2003年   11825篇
  2002年   11259篇
  2001年   6300篇
  2000年   6411篇
  1999年   5679篇
  1998年   988篇
  1997年   849篇
  1996年   810篇
  1992年   3329篇
  1991年   2973篇
  1990年   2863篇
  1989年   2648篇
  1988年   2492篇
  1987年   2328篇
  1986年   2190篇
  1985年   2024篇
  1984年   1500篇
  1983年   1304篇
  1982年   760篇
  1979年   1310篇
  1978年   935篇
  1977年   900篇
  1975年   877篇
  1974年   1033篇
  1973年   1041篇
  1972年   974篇
  1971年   976篇
  1970年   886篇
  1969年   938篇
  1968年   811篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
Peripheral blood lymphocytes of patients undergoing radiation therapy for pelvic tumours have been examined for the presence of dicentric and centric ring chromosomes. Blood samples were taken, by venipuncture, prior to the first radiotherapy session and 24 h after radiotherapy sessions to allow the mixing of the irradiated lymphocytes in the circulating blood. The yield of dicentrics and centric rings was best fitted by a straight line which, according the maximum likelihood method, corresponds to Y = 1.77 +/- 0.0003 10(-2) D. On this basis the dose inducing ten dicentrics or rings is 5.62 Gy at the target volume and, thus, is intermediate between the doses at the target volumes displaying the same effects in patients treated for mammary carcinoma (15 Gy) or for ankylosing spondylitis (2 Gy).  相似文献   
93.
94.
95.
96.
Enoximone is a positive inotropic agent belonging to the group of phosphodiesterase F-III inhibitors. The drug was tested in 34 patients uncontrolled by sympathomimetic drugs and referred to our department for urgent heart transplantation or circulatory assistance. After insertion of a Swan-Ganzgatheter and a radial artery catheter for haemodynamic monitoring, enoximone was administered as a 15-minute intravenous bolus injection of 1 to 2.5 mg/kf every 8 hours, in addition to sympathomimetic agents. Clinical and haemodynamic improvement was observed after thirty minutes in 30 patients. The cardiac index rose from 1.82 to 2.67 l/min/m2 and the pulmonary wedge pressure fell from 30.8 to 18.9 mmHg. Systemic arterial resistance decreased from 2170 to 1520 dyn. s. cm-5, and pulmonary resistance from 5.5 to 4.6 Wood units (p less than 0.01 for all values). Four patients had no haemodynamic improvement and were put on circulatory assistance, using a Jarvik 7 total artificial heart in 3 of them and heterotopic circulatory assistance in one. After clinical investigation for contra-indication to heart transplantation, and as their improved haemodynamic status permitted, 12 of the 30 patients were considered suitable (group B) for heart transplantation. Transplantation was performed within a week of admission in 11 patients without any need for mechanical assistance. One of the group B patients who required implantation of a Jarvik 7 artificial heart died after 12 hours of assistance. Eighteen patients were considered unsuitable for transplantation (group A) and treated medically.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
97.
PURPOSE: The objective of the current study was to determine the ability of some antiemetic compounds to cross the blood-brain barrier (BBB) and thereby to determine possible side effects of compounds for the central nervous system (CNS). METHODS: We compared the brain penetration of some antiemetic compounds using an in vitro BBB model consisting in brain capillary endothelial cells co-cultured with primary rat glial cells. RESULTS: This study clearly demonstrated that the metopimazine metabolite, metopimazine acid, has a very low brain penetration, lower than metopimazine and even less than the other antiemetic compounds tested in this study. CONCLUSIONS: The poor brain penetration of metopimazine acid, metopimazine biodisponible form, seems very likely related to the clinically observed difference in therapeutic and safety profile.  相似文献   
98.
99.
P. Ruffié  J. Margery 《Oncologie》2007,9(5):335-339
Asbestos has been used extensively in industrialised countries for more than a century, causing ongoing increases in mortality from mesothelioma. Despite its regulation and ban in France in 1997, and because of the 30-year cancer latency period after exposure to it, mortality from mesothelioma will continue to increase in the country for several decades, peaking between 2020 and 2030. The risk of mesothelioma from asbestos exposure is dose dependent and higher for amphiboles. For lung cancer, the risk increases linearly with cumulative exposure, regardless of the type of asbestos; this risk is similar in the presence or absence of pleural plaques. Smoking acts with asbestos to greatly increase the risk of lung cancer, but the effects of asbestos and smoking are independent. Regarding low-level exposure, an excess of mesothelioma and lung cancer has been observed in the vicinity of mines, asbestos manufacturers and natural geologic sites (para-occupational, domestic and environmental exposure); we have been unable to demonstrate safe levels of asbestos exposure.  相似文献   
100.
In order to establish a venom fingerprint and a peptide profile of the Lasiodora parahybana tarantula venom gland, we used conventional methods such as reversed phase liquid chromatography coupled to an electrospray-ionisation hybrid quadrupole time of flight mass spectrometer (LC/ESI-QqTOFMS), matrix-assisted laser desorption/ionization time-of-flight-MS (MALDI-TOFMS) and direct study of L. parahybana venom by nanospray-ionization QqTOFMS (nanoESI-QqTOFMS) and a new technology for the direct analysis of fresh tissues using MALDI-TOFMS. The analysis of the crude venom allowed the characterization of specific juvenile and adult biomarkers. In situ MALDI analysis of L. parahybana venom gland sections revealed different peptide expression levels all along the gland and non-processed peptide precursors, demonstrating the power of the method for the dynamic investigation of peptide evolution in the venom gland of spiders.  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