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   27179篇
  免费   2059篇
  国内免费   95篇
耳鼻咽喉   469篇
儿科学   1049篇
妇产科学   393篇
基础医学   2697篇
口腔科学   568篇
临床医学   2409篇
内科学   6218篇
皮肤病学   598篇
神经病学   1577篇
特种医学   1209篇
外国民族医学   1篇
外科学   5173篇
综合类   405篇
一般理论   16篇
预防医学   1234篇
眼科学   986篇
药学   2318篇
中国医学   48篇
肿瘤学   1965篇
  2023年   239篇
  2022年   215篇
  2021年   1165篇
  2020年   545篇
  2019年   947篇
  2018年   1154篇
  2017年   718篇
  2016年   777篇
  2015年   790篇
  2014年   1212篇
  2013年   1452篇
  2012年   2122篇
  2011年   2084篇
  2010年   1061篇
  2009年   961篇
  2008年   1514篇
  2007年   1483篇
  2006年   1382篇
  2005年   1181篇
  2004年   1049篇
  2003年   882篇
  2002年   761篇
  2001年   603篇
  2000年   568篇
  1999年   501篇
  1998年   177篇
  1997年   144篇
  1996年   135篇
  1995年   154篇
  1994年   115篇
  1993年   100篇
  1992年   270篇
  1991年   287篇
  1990年   250篇
  1989年   214篇
  1988年   209篇
  1987年   219篇
  1986年   192篇
  1985年   177篇
  1984年   111篇
  1983年   125篇
  1982年   85篇
  1981年   71篇
  1979年   129篇
  1978年   77篇
  1977年   68篇
  1975年   58篇
  1974年   65篇
  1973年   88篇
  1970年   58篇
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
71.
Summary Eight mares were infected with equid herpesvirus-1 subtype 1 isolated from a case of equine paresis. In two mares killed at 4 d.p.i. immunofluorescence showed endothelial cell infection together with thrombosis in the rete arteriosus of the nasal mucosa and also in the spinal cord of one of these mares. Circulating platelet counts in the other six mares fell as early as 2 d.p.i. and remained depressed for seven days. Circulating immune complexes started to appear at 2 d.p.i., reached maximum levels at 10 d.p.i., but were undetectable at 28 d.p.i. Three of the six remaining mares developed varying degrees of inco-ordination at 8 and 9 d.p.i. In the two inco-ordinate mares that were killed at 9 and 10 d.p.i. the haemorrhages in the spinal cord and brain were associated with extensive endothelial cell fluorescence and thrombus formation. Clinical paresis coincided with an increase in circulating complement fixing and neutralising antibodies which in all six mares were higher against the subtype 2 isolate than subtype 1.In five yearlings infected with a subtype 2 isolate of EHV-1 platelet counts remained normal and neither immune complexes nor viraemia, nor inco-ordination were detected.With 8 Figures  相似文献   
72.
Cocaine is a potent dopamine agonist that frequently stimulates the central nervous system and is often manifested by increased psychomotor activity, impulsivity, euphoria, and rapid thoughts. Attention deficit disorder (ADD) and bipolar disorder also present with physical restlessness, racing thoughts, distractibility, and mood instability. Although these three disorders rarely appear in the same individual, they are important differential diagnoses when considering any one illness with the above symptom complexes. We report two cases of cocaine abuse with ADD residual type in patients who were previously diagnosed as having atypical bipolar disorder. The adverse effects were reversed by the dopamine agonist bromocriptine.  相似文献   
73.
The effects of the calcium antagonists verapamil and nifedipine on blood glucose levels, glucose tolerance, insulin secretion during glucose tolerance and hypoglycaemic effect of tolbutamide were studied in normal nondiabetic rabbits. Daily dosage of 40 mg/kg verapamil and 5 mg/kg nifedipine given orally up to 7 days did not affect blood glucose level, glucose tolerance, insulin secretion during glucose tolerance and hypoglycaemic activity of tolbutamide 250 mg/kg p.o.  相似文献   
74.
Because chronic Mycoplasma pneumoniae respiratory infection is hypothesized to play a role in asthma, the potential of M. pneumoniae to establish chronic respiratory infection with associated pulmonary disease was investigated in a murine model. BALB/c mice were intranasally inoculated once with M. pneumoniae and examined at 109, 150, 245, 368, and 530 days postinoculation. M. pneumoniae was detected in bronchoalveolar lavage fluid by culture or PCR in 70 and 22% of mice at 109 and 530 days postinoculation, respectively. Lung histopathology was normal up to 368 days postinoculation. At 530 days, however, 78% of the mice inoculated with M. pneumoniae demonstrated abnormal histopathology characterized by peribronchial and perivascular mononuclear infiltrates. A mean histopathologic score (HPS) at 530 days of 5.1 was significantly greater (P < 0.01) than that for controls (HPS score of 0). Serum anti-M. pneumoniae immunoglobulin G was detectable in all of the mice inoculated with M. pneumoniae and was inversely correlated with HPS (r = -0.95, P = 0.01) at 530 days postinoculation. Unrestrained whole-body plethysmography measurement of enhanced pause revealed significantly elevated airway methacholine reactivity in M. pneumoniae-inoculated mice compared with that in controls at 245 days (P = 0.03) and increased airway obstruction at 530 days (P = 0.01). Murine M. pneumoniae respiratory infection can lead to chronic pulmonary disease characterized by airway hyperreactivity, airway obstruction, and histologic inflammation.  相似文献   
75.
BACKGROUND: Pravastatin and simvastatin prolong survival and reduce transplant-related coronary vasculopathy, although low-density lipoprotein (LDL) lowering with these agents is only modest. The objective of this study was to assess the safety of moderate dose atorvastatin and its efficacy when prior treatment with another statin had failed to lower LDL to < 100 mg/dl. METHODS: Data from 185 patients were retrospectively evaluated for adverse events, duration of exposure (person-days), and the mean atorvastatin dose exposure. Changes in lipid parameters, and prednisone and cyclosporine doses were determined. RESULTS: Safety: 48 patients received atorvastatin for 24,240 person-days at a mean dose exposure of 21 +/- 10 mg. Rhabdomyolysis, myositis, myalgias, and hepatotoxicity occurred in 0, 2, 2, and 0 patients, respectively. All events occurred at the 10-mg dose, within the first 3 months, and were rapidly reversible with atorvastatin discontinuation. Efficacy: Thirty-four patients evaluable for efficacy analyses had a pre-atorvastatin LDL of 145 +/- 38 mg/dl on the following statins: pravastatin (n = 30, 40 +/- 0mg), fluvastatin (n = 3, 33 +/- 12 mg), simvastatin (n = 1, 40 mg). After atorvastatin (21 +/- 9 mg/day) for 133 +/- 67 days, LDL was reduced to 97 +/- 24 mg/dl (relative reduction 31 +/- 20%, p < 0.0001). At the end of the observation period (418 +/- 229 days, atorvastatin final dose 24 +/- 14 mg/day), LDL was further decreased to 88 +/- 23 mg (relative reduction 37 +/- 17%, p < 0.0001). CONCLUSION: Atorvastatin, when used at moderate doses and with close biochemical and clinical monitoring, appears to be safe and is effective in aggressively lowering LDL in heart transplant recipients when treatment with other statins has failed to achieve LDL goals.  相似文献   
76.
The possible involvement of ionotropic and metabotropic quisqualate (QA) receptors in neuronal plasticity was studied in cultured glutamtergic cerebellar or hippocampal cells in terms of the specific activity of phosphate-activated glutaminase, an enzyme important in the synthesis of the putative neurotransmitter pool of glutamate. When cerebellar of hippocampal neurons were treated with QA, it elevated the specific activity of glutaminase in a dose-dependent manner. The half-maximal effect was obtained at about 0.1 μM, the maximum increase was at about 1 μM, but levels higher than 10 μM QA produced progressive reduction in glutaminase activity. In contrast, QA had little effects on the activities of lactate dehydrogenase and aspartate aminotransferase and the amount of protein, indicating that the increase in glutaminase was relatively specific. The QA-mediated increase in glutaminase was mimicked by the ionotropic QA receptor agonist -amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA; EC50, about 0.5 μM), but not by the metabotropic QA receptor agonist trans-(±)-1-aino-cyclopentyl-1,3,dicarboxyalte (t-ACPD; up to 0.5 mM). The specific ionotropic QA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) inhibited QA- and AMPA-mediated increases in glutaminase activity in a dose-dependent manner, whereas other glutamate receptor antagonists, -2-amino-5-phosphonovalerate, γ- -glutamyl aminomethyl sulphonic acid and γ- -glutamyl diethyl ester were ineffective. The elevation of neurotransmitter enzyme was Ca2+-dependent. The increase in Ca2+ influx essentially through the activation of L-type voltage-operated Ca2+ channels, and not the mobilization of internal Ca2+ stores, was responsible for these QA receptor-mediated long-term plastic changes in hippocampal and cerebellar neurons.  相似文献   
77.
78.
79.
Surgical techniques for endoscopic resection of bladder cancer.   总被引:2,自引:0,他引:2  
Accompanying the advances in surgical techniques and new intravesical and systemic therapeutic agents for the treatment of individuals with bladder cancer has been the development of greatly improved instrumentation for viewing the interior of the urinary tract and removing neoplasms. Fiberoptic lenses can now be combined with a video system, which enables the urologist to examine the lower urinary tract, not only more easily but with greater magnification. Training is obviously accelerated with the use of video endoscopy. The system also provides the opportunity for documentation and transmittal of the operative findings using either still or motion photography. The endoscopic procedure should be carried out in an orderly fashion. Sufficient lenses and cautery loops must be available to visualize the entire lower urinary tract and to biopsy or resect any abnormality and ensure hemostasis. The urologist should work closely with the pathologist to obtain sufficient cytologic and pathologic material to be confident of the presence or absence of tumor.  相似文献   
80.
We present our experience with twenty children with insulin dependent diabetes mellitus admitted during the past 2 1/2 years. Sixteen patients were admited with acute onset of ketoacidosis while four were having gradual onset. Active and symptomatic treatment was started in all diabetic ketoacidotic patients. One patient died during the acute stage. Eleven patients were followed for 3–6 months or more. Glycosylated hemoglobin was considered as a criteria for control. Three had good control, two fair and six poor control; six developed diabetic ketoacidosis and three developed hypoglycemia  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