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   11708篇
  免费   541篇
  国内免费   60篇
耳鼻咽喉   138篇
儿科学   146篇
妇产科学   105篇
基础医学   1486篇
口腔科学   252篇
临床医学   741篇
内科学   2698篇
皮肤病学   204篇
神经病学   942篇
特种医学   438篇
外科学   2381篇
综合类   48篇
一般理论   1篇
预防医学   441篇
眼科学   188篇
药学   970篇
中国医学   39篇
肿瘤学   1091篇
  2022年   68篇
  2021年   207篇
  2020年   111篇
  2019年   158篇
  2018年   182篇
  2017年   151篇
  2016年   208篇
  2015年   183篇
  2014年   231篇
  2013年   349篇
  2012年   470篇
  2011年   569篇
  2010年   289篇
  2009年   283篇
  2008年   406篇
  2007年   508篇
  2006年   483篇
  2005年   468篇
  2004年   474篇
  2003年   448篇
  2002年   505篇
  2001年   427篇
  2000年   453篇
  1999年   413篇
  1998年   169篇
  1997年   137篇
  1996年   110篇
  1995年   85篇
  1994年   82篇
  1993年   80篇
  1992年   354篇
  1991年   313篇
  1990年   313篇
  1989年   293篇
  1988年   286篇
  1987年   286篇
  1986年   276篇
  1985年   215篇
  1984年   146篇
  1983年   144篇
  1982年   51篇
  1981年   56篇
  1979年   115篇
  1978年   60篇
  1977年   59篇
  1974年   54篇
  1973年   62篇
  1972年   65篇
  1970年   49篇
  1969年   47篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Effects of TPE on prevention of hepatic failure after massive hepatectomy were studied experimentally using dogs. A 70% or 85% hepatectomy (Hx) was performed two weeks after TPE. All of the 70%Hx groups with(+)/without(-) TPE were alive for over two weeks after hepatectomy. While all of the 85%Hx group without TPE died, eight of ten in the 85%Hx group with TPE survived. Without TPE, total bilirubin levels in sera were elevated markedly in the 85%Hx group and moderately in the 70%Hx group after hepatectomy. The levels of escaped enzymes in sera, such as GOT or GPT, were also elevated remarkably in the TPE(-) groups. Although the levels of these enzymes were also high in the 85%Hx.TPE(+) group, these values were as same as those of 70%Hx.TPE(-) group. In the 85%Hx.TPE(-) group, critical diminution of functional hepatic cell mass and severe portal hypertension occurred after hepatectomy and coagulopathy and death followed to these phenomena. TPE might prevent the onset of these critical phenomena, and diminish the damage caused by massive hepatectomy. These results suggest that TPE is useful for prevention of postoperative hepatic failure so that we could perform massive hepatectomy safely, and extend the operative indication.  相似文献   
42.
The effects of platelet-derived growth factor (PDGF) on phospholipase D (PLD) activity and deoxyribonucleic acid (DNA) synthesis in rat C6 glioma cells have been investigated. Pretreatment of serum-starved C6 cells with PDGF results in enhanced choline production and the phosphatidylethanol (PEt) formation in the presence of ethanol, indicating the activation of PLD acting on phosphatidylcholine (PC). The dose-response curve for choline generation and DNA synthesis were comparable. In addition, the effects of PDGF on both PEt formation and [3H]thymidine incorporation into acid-precipitable material was blocked by the potent protein kinase C (PKC) inhibitor 1-(5-isoquinolinesulphonyl)-2-methylpiperazine (H-7) but not by N-(2-guanidinoethyl)-5-isoquinolinesulphonamide (HA1004), a relatively weak inhibitor of PKC, suggesting that PDGF plays an important role as a positive regulator of glioma cell growth via a PLD-mediated mitogenic signal transduction cascades, which depends largely on the activation of PKC.  相似文献   
43.
N Ogura  Y Baba  I Sakai  K Taneichi  H Shibaki 《Ryūmachi》1992,32(5):508-14; discussion 512-3
We report a 28-year-old woman with systemic lupus erythematosus (SLE) who showed tubulo-interstitial nephritis (TIN) without any glomerular changes. In 1990, she was admitted to our hospital, complaining of anorexia, vomiting and persistent high fever. Laboratory findings showed proteinuria, pancytopenia, hypocomplementemia and positive for antinuclear antibody, anti-DNA antibody, anti-Sm antibody, anti-SSA antibody and anti-SSB antibody. We made a diagnosis of SLE. Furthermore, distal renal tubular acidosis and asteatosis cutis were revealed. The diagnosis of Sj?gren's syndrome was not made. We treated with high-dose prednisolone (60mg/day) and achieved improvement of symptoms and laboratory data. Open renal biopsy showed TIN without any glomerular changes. Predominant TIN is very rare in SLE. We discussed its pathogenesis and relation to the renal lesions of Sj?gren's syndrome.  相似文献   
44.
The complete nucleotide sequences of the variable region genes of the heavy and light polypeptide chains of a human monoclonal rheumatoid factor (RF) produced from a human-mouse heterohybridoma were determined. The antibody, designated YES8c, contained V kappa III, J kappa 2, VH1, JH4, and a D gene segment of 9 amino acids. The nucleotide sequences and the deduced amino acid sequences of the light chain variable region were remarkably homologous (97-98%) to previously described RF of the Wa idiotypic family (PAY, GLO, CUR, FLO, and GAR) and to that of a V kappa III germline gene (Humkv325). The YES8c heavy chain variable region gene was most closely related to the VH1 gene of the restricted human fetal repertoire, designated 51p1, and also to 3 rearranged VH1 genes that were recently isolated from patients with chronic lymphocytic leukemia. These results suggest that variable region genes of RFs are highly conserved and that YES8c VH, as well as V kappa, may be identical to heavy and light chains expressed during early B cell development.  相似文献   
45.
A 6-year-old boy was successfully operated on for double outlet ventricle, common atrioventricular canal with severe valvular regurgitation, right atrial Isomerism, L-loop ventricles, total anomalous pulmonary venous connection, and pulmonary stenosis with hypoplastic left pulmonary artery. The Interventricular rerouting from the left ventricle to the ascending aorta was performed with a spiral patch, the lnteratrlal switching was performed by a Mustard patch, the common atrioventricular orifice was partitioned and valve repair was performed, and an 18-mm valved conduit was inserted between the right ventricle and the pulmonary artery. Although the patient had a small residual ventricular septal defect and pulmonary stenosls, the patient Is alive and well.  相似文献   
46.
TRK-100 (0.03, 0.1 and 0.3 mg/kg, p.o.), a chemically stable analogue of prostacyclin, dose-dependently prevented blood coagulation and glomerular fibrin deposition which were enhanced by 4 hr infusion of endotoxin (100 mg/kg) in rats. In addition, TRK-100 suppressed the generation of endotoxin-induced tissue thromboplastin like activity in cultured human endothelial cells.  相似文献   
47.
We determined nasal peak flow using a peak flowmeter with a face mask (PALROD peak expiratory flowmeter) and nasal airway patency with an anterior rhinomanometer (Nihon Koden MPR-1100) at a minimum time interval in the same individual. We compared the values obtained by two kinds of measurements to evaluate the usefulness of the peak flowmeter for nasal airway patency. In this study, the nasal patencies were experimentally changed and measured in 30 patients using alpha-1 stimulant spray and in 25 patients with nasal allergy using nasal provocation of antigens. We also measured the natural circadian changes of nasal patency in 21 patients with nasal allergy and in 18 normal persons every two hours from 8:00 A.M. to 8:00 P.M. and from 9:00 A.M. to 9:00 P.M., respectively. As a result, we found close correlations between percent change of the peak flow and the nasal airway patency measured after spraying alpha-1 stimulant (r = 0.699, p less than 0.01), after antigen provocation (r = 0.585, p less than 0.01), and during circadian change (r = 0.464, p less than 0.01 in normal persons and r = 0.251, p less than 0.05 in allergy patients). In conclusion, peak flowmeter is handier and cheaper than rhinomanometer and is useful in evaluating the effect of vasoconstrictors and nasal provocation on nasal patency and in measuring the circadian changes of nasal patency. Since nasal secretion in the nose affects the measurement of peak flow, it should be removed as much as possible immediately before the flowmeter is used.  相似文献   
48.
Innate immunity and its role against infections.   总被引:5,自引:0,他引:5  
LEARNING OBJECTIVES: This article reviews current concepts of the innate immune system that offers protection against infections. It offers an overview for the readers to understand how innate immunity, consisting of different receptors, cells, and mediators recognizes pathogens and exerts protective function against pathogens. DATA SOURCES AND STUDY SELECTION: MEDLINE-search articles including original research papers, review articles, textbooks, and references identified from bibliographies of relevant articles. RESULTS AND CONCLUSIONS: The innate immune system is nonspecific immunity present since birth not requiring repeated exposure to pathogens. It is capable of differentiation between self and nonself. Because of its nonspecificity, it has a broad spectrum of resistance to infection. Further, it is thought to play an important role in the control of adaptive immunity by regulating co-stimulatory molecules and effector cytokines. Innate immunity includes pattern recognition molecules/receptors, antimicrobial peptides, the complement system, inflammatory mediators, and cytokines produced by immune cells. Pattern recognition molecules/receptors recognize pathogen-associated molecular patterns that are essential for microorganisms' survival and pathogenicity. Although innate immunity has recently gained increasing importance, further studies are necessary for a better understanding of its role.  相似文献   
49.
50.
A study was made on the effect of detection wavelength and separation mode of HPLC on determination of urinary hippuric acid (HA) and three isomers of methylhippuric acid (MHA). The interference of other constituents of urine in the determination was effectively decreased by detection at a short wavelength of 227.6 nm. Meta and para MHAs were separated by the addition of beta-cyclodextrine to the mobile phase. Four metabolites were successfully separated from other components of urine by the combination of ODS-silica packed-column and mobile phase (method F). The detection limits were found to be 50 and 5 mg/l for HA and MHAs, respectively. MHAs could not be detected in the non-exposed subjects. Average levels (+/- SD) of HA in non-exposed males and females were 272.2 (+/- 210.8) and 393.0 (+/- 269.8) mg/l, respectively. The urinary levels of HA in females were significantly higher than those in males.  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