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   2563篇
  免费   151篇
  国内免费   10篇
耳鼻咽喉   18篇
儿科学   66篇
妇产科学   47篇
基础医学   349篇
口腔科学   73篇
临床医学   177篇
内科学   586篇
皮肤病学   84篇
神经病学   314篇
特种医学   57篇
外科学   429篇
综合类   9篇
预防医学   77篇
眼科学   53篇
药学   149篇
中国医学   6篇
肿瘤学   230篇
  2023年   21篇
  2022年   28篇
  2021年   84篇
  2020年   39篇
  2019年   57篇
  2018年   62篇
  2017年   49篇
  2016年   55篇
  2015年   54篇
  2014年   68篇
  2013年   97篇
  2012年   137篇
  2011年   132篇
  2010年   81篇
  2009年   73篇
  2008年   149篇
  2007年   145篇
  2006年   121篇
  2005年   131篇
  2004年   101篇
  2003年   95篇
  2002年   107篇
  2001年   83篇
  2000年   59篇
  1999年   57篇
  1998年   22篇
  1997年   18篇
  1996年   20篇
  1995年   14篇
  1994年   16篇
  1992年   38篇
  1991年   36篇
  1990年   32篇
  1989年   35篇
  1988年   30篇
  1987年   27篇
  1986年   30篇
  1985年   39篇
  1984年   17篇
  1983年   13篇
  1979年   15篇
  1978年   13篇
  1976年   14篇
  1974年   13篇
  1973年   17篇
  1972年   18篇
  1971年   22篇
  1970年   22篇
  1969年   19篇
  1966年   17篇
排序方式: 共有2724条查询结果,搜索用时 18 毫秒
1.
2.
We reported on the unusually high isotope effect of non-aromatizing androgen 19-hydroxylase in sheep and dog adrenals and the validity of the [3H] water method using [19-3H3] androgen. We have extended the study to examine whether this 19-hydroxylation is catalyzed by a cytochrome P-450 dependent enzyme. Sheep adrenal homogenate (1.65 mg prot.) was incubated in the presence of NADPH (5.6mM) with [19-3H3, 4-14C]-androstenedione (A) (3.2 microM, 8.24 x 10(4) dpm 3H/micrograms, 3H/14C = 17.2) in a total of 1.2 ml PO4 buffer under air at pH 7.4 for 2, 5 and 10 min. [19-3H2, 4-14C]-19-hydroxy-A (19-OHA) with added carrier was purified through extraction, TLC, acetylation to form 19-AcOA, and further TLC to give 19-hydroxylase activity as assessed by the product isolation method. Simultaneously, the [3H] water was measured by distillation, and with correction by the apparent kinetic isotope effect (KH/KT = 11.8), used for assessment of 19-hydroxylase activity. The effects on the hydroxylation by cofactor (NADPH, NADH), incubation atmosphere (N2, CO/O2), cytochrome P-450 inhibitors (metyrapone, clotrimazole) and heating were measured by both methods. Compared to the complete system (89.6pmol/min/mg as 100%), carbon monoxide suppressed 15.8, 59.3 and 86.4% of the 19-hydroxylation when a CO/O2 ratio of 0.1, 1 and 9 was used, respectively. Replacement to nitrogen atmosphere decreased the activity by 93.8%. Replacement of NADPH with NADH (7.5mM) caused more than a 92.1% decrease in activity. Metyrapone at 50 and 200 microM and and clotrimazole at 2.5 and 10 microM suppressed the activity by 82.8, 90.4, 85.4 and 94.9%, respectively. A larger scale sheep adrenal incubation of A (250 microM) under 18O2 atmosphere and isolation of 19-AcOA were carried out in a similar manner. The gas chromatography-mass spectrometry analysis of the purified product showed 48.5% of the product to be 18O-labeled as [M+ + 2], m/e 346. Thus, the non-aromatizing androgen 19-hydroxylase requires NADPH and molecular oxygen. It is strongly inhibited by carbon monoxide and cytochrome P-450 inhibitors. These results indicate that the enzyme system responsible for non-aromatizing androgen 19-hydroxylase in adrenal is a cytochrome P-450 dependent monooxygenase.  相似文献   
3.
Invasive aspergillosis (IA) is a severe complication of liver transplantation. Risk factors for IA after deceased donor liver transplantation (DDLT) have been presented in several reports, but are not well established for living donor liver transplant recipients. Here, a retrospective case-control study was performed. Five cases with IA were investigated after living donor liver transplantation (LDLT) between January 1999 and December 2002 at Kyoto University Hospital. For comparison, living donor liver transplant recipients without IA were taken as controls. These patients had undergone LDLT 1 month before or after each IA case and had the same survival times as the latter. We evaluated the clinical and laboratory findings for both groups up until their demise. Patients with IA after LDLT had a very poor prognosis. By univariate analysis, risk factors for IA were preoperative intensive care unit stay (P = 0.02) and preoperative steroid administration (P = 0.02). Preoperative steroid administration for fulminant hepatitis possibly predisposed to the development of IA after LDLT.  相似文献   
4.
S Nomura  G Osawa  M Karai 《Nephron》1990,55(2):210-213
A 41-year-old hemodialyzed woman developed ascites and was found to have secondary iron overload. The dose of administered iron was approximately 11-12 g, and her serum ferritin level was 15,000 ng/ml (15,000 micrograms/l). There were no signs of congestive heart failure, fluid overload, or liver cirrhosis. A program of weekly phlebotomy combined with recombinant human erythropoietin (rhEPO) therapy was tried to eliminate the iron congestion. After 9 months of this therapy, about 5 g of iron had been removed. The ascites completely disappeared, and her serum ferritin level fell to 5,800 ng/ml (5,800 micrograms/l). This suggests that such combined therapy would be useful when iron overload must be corrected rapidly. Before therapy, the sterile ascitic fluid showed exudative characteristics with 3.7 g/dl (37 g/l) of total protein. The serum-ascites albumin difference was 0.6 g/dl (6 g/l), and the fluid contained 1,400 inflammatory cells/mm3 (1.4 X 10(9)/l). Notably, the serum-ascites albumin difference increased in parallel with iron elimination. These findings suggested that iron deposition may have played a role in changing the permeability of the peritoneum, or in impairing lymphatic drainage, both of which are presumed to be pathogenetic factors of nephrogenic ascites.  相似文献   
5.
Immunological studies were performed in 87 patients with chyluria referred to our clinic from January 1982 to December 1988. White blood cell count in 78 patients was 5210.3 +/- 1440.9/mm3. The fraction and the number of lymphocyte were 18.7 +/- 9.5% and 934.1 +/- 521.6/mm3, respectively: they were lower than normal limit. The percentages of T and B lymphocytes studied in 46 patients were 79.3% +/- 11.2% (normal range: 76-86) and 10.4 +/- 7.9% (normal range: 8-16), respectively: both lymphocytes tended to decrease in percentage. Lymphocyte blast formation stimulated with phytohemagglutinin (PHA) was carried out in 20 patients. The mean of the blast formation was 17410.0 +/- 10275.1 c.p.m. (normal range: 377700-62400), and much lower than normal value. Of 22 patients who had PPD skin test, only 9 (40.9%) were positive. These findings signified that cellular immunity was suppressed in patients with chyluria. On the other hand, the value of immunoglobulin was within normal range (IgG: 1325.3 +/- 475.6 mg/dl, IgA: 242.0 +/- 98.3 mg/dl, IgM 130.4 +/- 95.9 mg/dl). Study on the values of laboratory examinations showed statistically positive correlation between total lymphocyte population and T cell number, and between total lymphocyte population and lymphocyte blast formation. In patients with chyluria, serious sequelae have not been reported. However, care should be taken for possible opportunistic infection and, particularly, malignant tumors because suppression of cellular immunity may be one of the promoting factors of malignant tumors.  相似文献   
6.
An elderly case of idiopathic retroperitoneal fibrosis (IRPF) with bilateral ureteral obstruction was reported. A 74-year-old man was admitted with complaints of general fatigue and loss of appetite. An elastic hard mass with a smooth surface was palpated in the left upper quadrant of the abdomen. Abnormal ESR and CRP were noticed. Abdominal ultrasonography showed both a homoechoic mass which surrounded the aorta in the retroperitoneal space and bilateral hydronephrosis. Computed tomography revealed a retroperitoneal mass involving bilateral ureters. Magnetic resonance imaging demonstrated a mass with a sharp image and signal intensity. Furthermore the morphological relationship between the mass and the ureters and major vessels clearly indicated the characteristics of benign retroperitoneal fibrosis. Based upon the above findings, a diagnosis of IRPF was made. After confirming the histological diagnosis by biopsy, treatment consisting of bilateral ureterolysis, intra-abdominal transposition of ureters and oral administration of prednisolone was performed, resulting in a normalization of laboratory findings. Analysis of 86 previously cases of IRPF reported up to 1990 in Japan, revealed the peak age to be in the 7th decade with predominance in males (males: females = 57:29).  相似文献   
7.
Background We previously found that glomerular epithelial cells play an important role in the formation of adhesive lesions. Glomerular sclerotic lesions develop after the inital adhesive lesions. Methods Two series of experiments were done with spontaneously diabetic WBN/Kob rats. These rats develop segmental glomerular sclerotic lesions with aging. The first series of experiments was intended to clarify the kinetics of glomerular cells on progressive glomerular damage in these rats. The second series of experiments was designed to study the relationship between proliferation (judged by % bromodeoxyuridine-positive cells) of glomerlar epithelial cells and sclerotic lesions with adhesions. Results In the first series, rats having increased proteinuria showed segmental glomerular sclerotic lesions with adhesions. At the same time, increased labeling indices of tuft cells and epithelial cells of Bowman's capsule were observed. In the second series, no significant increase in the labeling indices of tuft cells with sclerotic lesions was observed, compared to tuft cells without sclerotic lesions. In sclerotic lesions with adhesion, bromodeoxyurdine-positive cells were observed that were not distinguishable as podocytes or epithelial cells of Bowman's capsule. The highest labelling index was noted in the epithelial cells of Bowman's capsules with sclerosis. Conclusion This study shows that the proliferation of glomerular epithelial cells (mainly epithelial cells of Bowman's capsule) occurs in glomerular sclerotic lesions with adhesions.  相似文献   
8.
As a model system for mucocutaneous lymph node syndrome (MCLS), we have advocated and used mice which had been rendered tolerant to Streptococcus pyogenes-associated antigens by neonatal infection with group A fteta-hemolytic streptococci, because these mice have shown a variety of peculiar bioimmunological characteristics bearing a striking resemblance to those of MCLS patients. The results of our current investigations reaffirmed the reliability of the animal model by indicating that mice subjected to neonatal infection with 5. pyogenes , or inoculation with streptococcal pyrogenic exotoxin (SPE) in Freund's adjuvant, were perfect counterparts of patients with MCLS on account of their platelet activation and hyperaggregability in response to provocative treatment, which are familiar findings in this disease.  相似文献   
9.
Summary A newly designed attachment device of the multipurpose head frame (Sugita) for Neuronavigator (Watanabe) is presented with an illustrative case of glioblastoma in an eloquent area. This has extended the usefulness of the neuronavigator for those who prefer and use the multipurpose head frame, while the requirements for keeping a stereotactic combination and the original concept of the multipurpose head frame, as well as that of the neuronavigator have been kept undisturbed.  相似文献   
10.
Aneurysmal rupture into the intestinal tract is a rare but disastrous complication of an internal iliac artery aneurysm. We report herein the successful surgical repair of a fistula between a huge aneurysm of the right internal iliac artery and the rectum in an 81-year-old man. After a femoro-femoral cross-over bypass had been performed, the aneurysm was opened and its patent arterial branches were ligated with sutures. The fistula was then intra-aneurysmally sutured and covered with an omental flap. The diagnostic and therapeutic approaches to this severe complication are discussed with a review of the literature following the presentation of this case.  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