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   3931777篇
  免费   293342篇
  国内免费   6748篇
耳鼻咽喉   56469篇
儿科学   124528篇
妇产科学   105562篇
基础医学   565426篇
口腔科学   112394篇
临床医学   361423篇
内科学   751044篇
皮肤病学   83435篇
神经病学   319634篇
特种医学   151402篇
外国民族医学   1278篇
外科学   590586篇
综合类   89583篇
现状与发展   13篇
一般理论   1605篇
预防医学   317619篇
眼科学   93822篇
药学   294199篇
  14篇
中国医学   7552篇
肿瘤学   204279篇
  2018年   42188篇
  2017年   32018篇
  2016年   35713篇
  2015年   40350篇
  2014年   57692篇
  2013年   87778篇
  2012年   119363篇
  2011年   126875篇
  2010年   75465篇
  2009年   71430篇
  2008年   119465篇
  2007年   127265篇
  2006年   128496篇
  2005年   124887篇
  2004年   120149篇
  2003年   115594篇
  2002年   113224篇
  2001年   175052篇
  2000年   180558篇
  1999年   152797篇
  1998年   45607篇
  1997年   40444篇
  1996年   40026篇
  1995年   38333篇
  1994年   35727篇
  1993年   33542篇
  1992年   121605篇
  1991年   118636篇
  1990年   115298篇
  1989年   111067篇
  1988年   102937篇
  1987年   101092篇
  1986年   95436篇
  1985年   91710篇
  1984年   69263篇
  1983年   59092篇
  1982年   35804篇
  1981年   32047篇
  1979年   64977篇
  1978年   46076篇
  1977年   38666篇
  1976年   36876篇
  1975年   39083篇
  1974年   47663篇
  1973年   45379篇
  1972年   42878篇
  1971年   40119篇
  1970年   37353篇
  1969年   35156篇
  1968年   32287篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
961.
Trends in analgesic self-poisoning in West-Fife, 1971-1985   总被引:1,自引:0,他引:1  
All admissions for analgesic self-poisoning to a district poisons unit over a 15-year period have been reviewed. During this time overdose with analgesic drugs increased to represent almost half of all admissions for self-poisoning. The types of analgesics taken in overdose also changed significantly during the period of this review. Aspirin and Distalgesic poisoning declined in incidence and more cases of self-poisoning by paracetamol and non-steroidal anti-inflammatory agents were seen. The impact of these changes on the medical management and outcome of deliberate self-poisoning is analysed. The reasons behind the trends described in this paper are assessed and their implications for future prevention and treatment are discussed.  相似文献   
962.
We review evidence suggesting that deaf speakers do not move their articulators toward the following open posture throughout closure and report results from a preliminary cinefluorographic study. Two prelingually deaf and two hearing speakers produced two different strings of alternating heterogeneous monosyllables as though speaking in time with a metronome (the so-called P-center task). Events traditionally associated with vowel production appeared evenly timed throughout the productions, and, in general, the deaf speakers performed similarly to the hearing speakers. We relate the results to Fowler's (1983) interpretation of the P-center phenomenon as an indicant of continuous vowel production.  相似文献   
963.
964.
965.
The purpose of this study was to determine whether blood lipid and lipoprotein concentrations varied in 5 men with advanced HIV-1 infection after 12 months of aerobic exercise training. Prior to exercise, the mean baseline cholesterol and high-density lipoprotein cholesterol (HDL-C) serum concentration were each lower, and mean baseline triglyceride concentration was higher compared to a healthy population norm. Consistent exercise training for 12 months failed to significantly (p > .05) alter cholesterol or HDL-C. Triglyceride concentration was significantly (p < .05) elevated above baseline (63 mg/dL) regardless of exercise compliance. The results suggest that long-term exercise training cannot correct lipid profile abnormality, particularly hypertriglyceridemia, common to individuals with advanced HIV-1 infection.  相似文献   
966.
967.
Cardiovascular function was studied in anaesthetised male rats which received 50 micrograms/ml of arsenic (as sodium arsenate) in deionised drinking water for 320 days. High urinary excretion of arsenic was found at the end of treatment and the metal accumulated considerably in the kidneys and liver, which both presented slight alterations. No histopathological modifications were evident in other organs. Base line blood pressure, cardiac inotropism, and chronotropism and cardiovascular reactivity to noradrenaline, acetylcholine, angiotensin II, bradykinin, histamine, and serotonin did not differ in exposed or in control animals. In the exposed group, however, there was potentiation of the effects of vascular beta-adrenoceptor stimulation and a reduction in the vascular responsiveness to angiotensin I. Chronic arsenic exposure did not affect the baroreflex sensitivity but was able to induce sympathetic hyperactivity or hypersensitivity, or both, possibly associated with an antivagal action. Our results might help to explain the cardiovascular alterations seen in people chronically exposed to high concentrations of arsenic.  相似文献   
968.
969.
A major problem in tracheal transplantation is the restoration of an adequate vascular supply to the transplanted trachea. In 12 piglets, a segment (6 rings) of thoracic trachea was removed and the excised segment was then sutured back in place. In 9 animals (group A), a vascularized omental flap was wrapped around the autotransplanted trachea. In the other 3 pigs (group B), the omentum was not used. Eight of 9 group A pigs were killed, 1 or 2 months later, having had no signs of airway obstruction; the 9th pig was killed after 14 days because of airway obstruction. The 3 pigs in group B were killed after 11 to 13 days because of progressive respiratory obstruction. In the 8 asymptomatic pigs in group A, the omental flap was viable and tracheal growth was normal with no differences in diameter between normal and autotransplanted trachea. Histologically intact cartilage was lined with respiratory epithelium. In the one group A pig who was killed early, the omental flap was necrotic. In this pig and in the 3 group B animals, extensive tracheal necrosis and nonviable cartilage were observed. These findings indicate that in the pig, a 6-ring segment of trachea can be transplanted with vascularization provided by an omental flap.  相似文献   
970.
Biopsies from the diseased bones of patients with familial expansile osteolysis (FEO) were examined by light and electron microscopy. Focal concentrations of multinuclear osteoclasts were present, and these contained viral-like microcylindrical inclusions which appeared exclusive to their nuclei. No consistent relationship was found between osteoclast size and the number of osteoclast nuclei containing microcylindrical inclusions. Quantitative histomorphometry showed evidence of increased bone remodelling with high bone cell densities and a decrease of the reversal period in bone remodelling. The lesions contained prominent woven bone and fibrovascular tissue, together with mononuclear cells and adipocytes. Little bone was found in the most radiolucent lesions, which were almost totally occupied by adipocytes and fibrovascular tissue. Serology did not reveal any significant differences between the viral antibody titres of patients and their age- and sex-matched controls. The present study suggests that intranuclear viral-like microcylindrical inclusions of osteoclasts are not a specific feature of Paget's disease, and are found in other disorders of osteoclast function, including pycnodysostosis, osteopetrosis, giant cell tumours, and familial expansile osteolysis.  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