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   5803篇
  免费   277篇
  国内免费   53篇
耳鼻咽喉   60篇
儿科学   89篇
妇产科学   79篇
基础医学   646篇
口腔科学   67篇
临床医学   388篇
内科学   1666篇
皮肤病学   45篇
神经病学   410篇
特种医学   204篇
外科学   1115篇
综合类   17篇
一般理论   2篇
预防医学   123篇
眼科学   76篇
药学   564篇
中国医学   12篇
肿瘤学   570篇
  2023年   28篇
  2022年   58篇
  2021年   81篇
  2020年   50篇
  2019年   81篇
  2018年   81篇
  2017年   66篇
  2016年   107篇
  2015年   100篇
  2014年   150篇
  2013年   147篇
  2012年   243篇
  2011年   272篇
  2010年   157篇
  2009年   149篇
  2008年   276篇
  2007年   277篇
  2006年   269篇
  2005年   266篇
  2004年   250篇
  2003年   256篇
  2002年   261篇
  2001年   221篇
  2000年   224篇
  1999年   215篇
  1998年   61篇
  1997年   39篇
  1996年   36篇
  1995年   35篇
  1994年   42篇
  1993年   23篇
  1992年   147篇
  1991年   152篇
  1990年   161篇
  1989年   179篇
  1988年   133篇
  1987年   136篇
  1986年   115篇
  1985年   114篇
  1984年   70篇
  1983年   49篇
  1982年   26篇
  1981年   20篇
  1979年   38篇
  1978年   27篇
  1977年   20篇
  1974年   25篇
  1972年   28篇
  1971年   23篇
  1969年   20篇
排序方式: 共有6133条查询结果,搜索用时 31 毫秒
71.
Prostaglandins, including PGD(2) and PGE(2), are produced during allergic reactions. Although PGD(2) is an important mediator of allergic responses, aspirin-like drugs that inhibit prostaglandin synthesis are generally ineffective in allergic disorders, suggesting that another prostaglandin-mediated pathway prevents the development of allergic reactions. Here we show that such a pathway may be mediated by PGE(2) acting at the prostaglandin E receptor EP3. Mice lacking EP3 developed allergic inflammation that was much more pronounced than that in wild-type mice or mice deficient in other prostaglandin E receptor subtypes. Conversely, an EP3-selective agonist suppressed the inflammation. This suppression was effective when the agonist was administered 3 h after antigen challenge and was associated with inhibition of allergy-related gene expression. Thus, the PGE(2)-EP3 pathway is an important negative modulator of allergic reactions.  相似文献   
72.
Nonspecific esterases of mononuclear phagocytes (MNs) were studied histochemically in the developing and healing tuberculous lesions produced in rabbit skin by bacille Calmette Guérin (BCG). Nonspecific esterases were assayed with the following substrates: naphthol AS-D acetate (AS-D), naphthol AS-D chloroacetate (AS-D Chl), naphthol AS acetate (AS) and alpha-naphthyl acetate (alpha-N), beta-Galactosidase, a lysosomal enzyme of MNs, was also assayed as a marker of MN activation. The number of MNs hydrolyzing AS-D Chl, AS, and alpha-N increased for 2 to 4 weeks after infection. These chronologic changes were similar to that of beta-galactosidase. In contrast, MNs hydrolyzing AS-D appeared predominantly in the healing lesions five to six weeks after infection. These MNs had the morphologic features of balloon-like cells. They contained few lysosomes and gathered in clumps far from the caseous center. The activity of the AS-D esterase was almost completely inhibited by various trypsin inhibitors, but not by the serine esterase inhibitor of phenylmethylsulfonyl-fluoride. These results suggest that the AS-D esterase is a trypsin-like esterase which participates in the healing of tuberculous lesions.  相似文献   
73.
Centromere protein-C (CENP-C), one of the centromere autoantigens and components of the inner plate of the kinetochore, is suggested to make a dimer at the C-terminus. In order to investigate the presence of conformation-specific anti-centromere antibodies (ACA) to the dimer form, the C-terminal 124 amino acids (CF-124) were expressed in Escherichia coli, affinity purified and chemically cross-linked. Immunoblotting was utilized to compare the reactivities between the dimers and the monomers against 58 ACA(+) sera. The reactivities of the dimers were obviously higher in both IgG and IgM responses. The dimer was still more reactive than the glutathione S-transferase-fused monomer in some sera. Two kinds of CF-124 mutant (each contained one amino acid change at the N-terminal region of CF-124) and two cut segments of CF-124 (67 N-terminal amino acids and 58 C-terminal amino acids) were also examined. The former two mutants decreased the dimerization activity. The latter two mutants lost both activities except for the faint dimerization activity of the N-terminal half. Affinity-purified antibodies with CF-124 in a liquid phase containing the co-purified GroE protein of E. coli, GroEL, reacted to the centromere in culture cells. In conclusion, there are heterogeneous autoepitopes including some conformational epitopes at the C-terminal CENP-C.  相似文献   
74.
This case series reports the outcome of posterior ankle decompression and os trigonum or Stieda process resection utilizing an open posterolateral approach in 54 professional, pre-professional, and dedicated recreational dancers. All procedures were performed by a single surgeon at the same facility between 2008 and 2018. The surgical technique is described in detail. Data related to results of the surgery were gathered via follow-up questionnaire and verified by referencing the patients’ medical records. Outcomes were self-assessed in terms of categories ranging from excellent through moderate to poor. Eighty-nine percent of the dancers (N = 48 of 54) chose excellent or good, 11% (N = 6) chose moderate, and none selected poor. These results were compared with those achieved in 17 previous studies reporting the use of both open (posterolateral and posteromedial) and arthroscopic/endoscopic techniques in dancers. This comparison found similarly favorable reported outcomes, but also great variation in methodology for determining patient reported outcomes (PROs). While the preferred surgical technique for posterior ankle decompression remains controversial, the open posterolateral approach utilized in this series resulted in high expectation of return to dance with minimal complications. The need for a dancer-specific PRO tool is discussed.  相似文献   
75.
Seven elderly patients, 79-88 years old, with bladder cancer were treated by transvesical tumorectomy with intraoperative radiation therapy (IORT). The cancers appeared to be of high grade and high stage by cystoscopy and other examinations, and consequently they were diagnosed to be over stage T2. Therefore, all patients were thought to be candidates for total cystectomy. But their ages and complications precluded this treatment, so we decided to carry out the "palliative" IORT. The operation of IORT required less than two hours and required less than 200 ml of blood loss. There were no complications such as hematuria, irritable bladder, and rectal symptoms. The postoperative stage diagnoses coincided with the preoperative ones in 5 cases, but two cases were overdiagnosed. Five patients died after more than one year and 11 months, but four patients died due to other diseases, without cancer. One patient died due to pulmonary cancer confirmed by autopsy. Recurrence was seen in one case. These results confirmed that IORT was effective for local control of bladder cancer and partially prophylactic for recurrence. Furthermore, this treatment seemed to be even curative for some cases. We recommend this modality of treatment for some of aged patients and patients with complications who are unable to undergo cystectomy.  相似文献   
76.
Overexpression of P-glycoprotein (Pgp) in tumors is one of the major mechanisms which mediates the multidrug resistance (MDR) phenotype. To evaluate the prognostic significance of Pgp in breast cancer, Pgp expression was examined in paraffin-embedded tissue sections of 94 breast cancer specimens by immunohistochemistry. Tissue specimens were obtained by mastectomy without preoperative chemotherapy. UIC2 monoclonal antibody which recognizes an extracellular epitope of human Pgp was employed. Of the 94 breast cancer specimens, 35 (37.2%) were positive for Pgp expression. Pgp expression had no correlation with menopausal or hormone receptor status, axillary lymph node involvement or tumor size. However, a significant correlation was observed between Pgp expression and disease relapse (p = 0.0322). Pgp-positive patients showed a significantly shorter disease-free survival period than Pgp-negative patients by the Kaplan-Meier method (p = 0.0433). These results suggest that immunohistochemical detection of Pgp in breast cancer tissue may have prognostic value after radical operation.  相似文献   
77.
We investigated the synergetic effects of 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H-7) on cis-diamminedichloroplatinum(II) (CDDP) cytotoxicity to KB cells, a human pharyngeal carcinoma cell line, and explored the possible mechanism whereby it exerted these effects. In vitro treatment with H-7 markedly decreased protein kinase C (PKC) activity in KB cells and significantly sensitized the cells to CDDP. Treatment of KB cells with H-7 induced a dose-dependent depletion of intracellular glutathione (GSH) levels. These results suggest that the decreased GSH content induced by H-7 may be involved in sensitizing KB cells to CDDP.  相似文献   
78.
We experienced two patients with single coronary artery who underwent CABG using arterial grafts successfully. In two patients coronary angiography demonstrated a single coronary artery which was originated in left coronary sinus and was bifurcated to LAD and LCx, and then RCA branched off proximal LAD, passing in front of the right ventricular out flow tract (Sharbaugh Type L-IIa). To the first patient, a 52-year-old man who had angina on exertion due to long stenosis of RCA, CABG to RCA using RITA was carried out. To the second patient, a 57-year-old man who had inferior myocardial infarction due to 90% stenosis of proximal LAD, CABG to RCA using RITA and LAD using LITA was carried out. Single coronary artery without additional congenital cardiac anomalies may lead to myocardial ischemia, necessitating CABG as coronary reconstructions.  相似文献   
79.
Drug dosage and appropriate size of medical equipment for emergency pediatric patients are determined by age, body weight and/or height. In an emergency situation, however, such information about the patients is not always clear. Body height is easily measured when the patient lies down supine. Furthermore, child's height could be a better parameter than age to predict appropriate endotracheal tube (ETT) size and body weight. We propose a new pediatric emergency scale tape (PES Tape). PES Tape is graduated in centimeters to measure body height in supine position. Height-based body weight, drug dosage, energy dosage for defibrillation, appropriate size of ETT and lip-tip distance (LTD) are printed on the tape. We studied the reliability of this tape in pediatric anesthesia. Body weight estimated from the tape was accurate, and predicted size of ETT and LTD was appropriate. PES Tape is a reliable tool in pediatric emergency.  相似文献   
80.
IgA deposition in the glomerular mesangial matrix is a prerequisite for the diagnosis of IgA nephropathy, and circulating IgA-containing complex has been implicated in this process. Since fibronectin is known to be involved in the assembly of extracellular matrix, this study was conducted to investigate whether fibronectin and its fragments are present in sera of patients and are capable of binding IgA1. Sera from patients with IgA nephropathy were purified by heparin-affinity chromatography, and column eluate were analyzed for the presence of fibronectin using Western blot and a set of anti-fibronectin monoclonal antibodies. Native fibronectin was digested with cathepsin D to obtain fragments similar to those of serum fibronectin. The capacity of fibronectin to bind IgA was examined with a mixture of purified IgA1 and cathepsin D-digested fibronectin fragments. A 43-kD carboxy-terminal fragment of fibronectin was detected in samples derived from sera of patients with IgA nephropathy but not in healthy control subjects. A similar-sized fragment was generated by cathepsin D digestion of the native molecule and was shown to bind to IgA1 in vitro. Since the carboxy-terminal domain is known to be critical in assembling exogenous fibronectin into the extracellular matrix, the affinity to IgA1 to a fragment found in patients may have pathogenic potential to mediate extracellular IgA deposition in IgA nephropathy.  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