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   1348篇
  免费   70篇
  国内免费   2篇
耳鼻咽喉   17篇
儿科学   13篇
妇产科学   23篇
基础医学   158篇
口腔科学   18篇
临床医学   102篇
内科学   259篇
皮肤病学   6篇
神经病学   94篇
特种医学   61篇
外科学   180篇
综合类   4篇
预防医学   35篇
眼科学   21篇
药学   116篇
中国医学   1篇
肿瘤学   312篇
  2023年   5篇
  2022年   13篇
  2021年   24篇
  2020年   14篇
  2019年   16篇
  2018年   19篇
  2017年   23篇
  2016年   17篇
  2015年   19篇
  2014年   22篇
  2013年   39篇
  2012年   67篇
  2011年   62篇
  2010年   31篇
  2009年   26篇
  2008年   62篇
  2007年   88篇
  2006年   49篇
  2005年   50篇
  2004年   59篇
  2003年   55篇
  2002年   63篇
  2001年   56篇
  2000年   51篇
  1999年   48篇
  1998年   22篇
  1997年   27篇
  1996年   12篇
  1995年   13篇
  1994年   9篇
  1993年   11篇
  1992年   38篇
  1991年   49篇
  1990年   34篇
  1989年   27篇
  1988年   18篇
  1987年   27篇
  1986年   24篇
  1985年   18篇
  1984年   8篇
  1983年   13篇
  1982年   8篇
  1979年   11篇
  1978年   9篇
  1977年   13篇
  1975年   7篇
  1973年   6篇
  1970年   4篇
  1968年   4篇
  1966年   4篇
排序方式: 共有1420条查询结果,搜索用时 797 毫秒
21.
Recent evidence suggests that an insertion/deletion (I/D) polymorphism of the gene encoding angiotensin-converting enzyme (ACE) is associated with myocardial infarction and related cardiovascular diseases. We investigated a possible association of the ACE polymorphism with essential hypertension in a total of 263 cases/controls from among the elderly (age, over 70 years) and middle-aged (age between 30 and 60 years) Japanese population. The frequency of the I/I homozygote was significantly higher in hypertensive subjects than in controls in the elderly age group (33/57 vs 16/46; P = 0.02), but no association was observed in the middle-aged group (25/75 vs 26/85; P = 0.71). Similarly, having at least one insertion allele was associated with essential hypertension in the elderly age group (83/114 vs 46/92 in controls; P = 0.001), but not in the middle-aged group (78/150 vs 94/170; P = 0.524). These data suggest that genetic variation at the ACE locus may be associated with some determinants for blood pressure in elderly persons, and imply the involvement of the ACE insertion/deletion polymorphism in the etiology of age-related essential hypertension in the Japanese population. Received: April 18, 2000 / Accepted: July 25, 2000  相似文献   
22.
We developed a mouse monoclonal antibody, S2n8, by immunizingmice i.p. with human decidual cells collected in the first trimesterof pregnancy. By indirect immunofluorescence staining of frozensections, S2n8 was found to react with decidual cells and endometrialstromal cells throughout the menstrual cycle, but not with endometrialglandular cells or with the endometrial surface epithelium.Judging from the fluorescence intensity, the antigen expressionon stromal cells was weak in the proliferative phase, and becamestronger in the secretory phase. Decidual cells in the firsttrimester of pregnancy and decidual cells at term showed strongexpression of this antigen. Indirect immunofluorescence stainingof enzymatically dispersed decidual tissue revealed that theS2n8 antigen was expressed on the decidual cell surface. Flowcytometric analysis of 12 freshly prepared stromal cell-enrichedcell suspensions showed that 74.8–94.2% (mean ±SD 86.1 ± 6.6%) of the cells carried the antigen. Theexpression of S2n8 antigen on cultured stromal cells was enhancedby the addition of oestradiol and/or progesterone. The antigenicmolecule was purified by immunoaffinity chromatography fromdecidua collected in the first trimester of pregnancy, and themolecular weight was estimated to be 140 kDa. These findingsindicate that the S2n8 antigen is a useful cell surface markerfor stromal cells/decidual cells and is associated with theirdifferentiation. cell surface antigen/decidual cells/endometrial differentiation/endometrial stromal cells/monoclonal antibody  相似文献   
23.
MRL/Mp-lpr/lpr (MRL/lpr) mice develop glomerular lesions with regular variations in their histopathological manifestations, similar to those in lupus nephritis. These lesions are mainly either cell-proliferative or wire loop-like and are associated with glomerular deposits of immunoglobulins, most frequently IgG and IgM. We previously established a nephritogenic IgG3-producing hybridoma clone, B1, from an MRL/lpr mouse, which induces only a 'wire loop-like' type of glomerular lesion when injected into SCID mice. Injection of SCID mice with an anti-trinitrophenyl IgM antibody-producing hybridoma clone, Sp6, following injection of the B1 clone, however, resulted in the development of a 'cell-proliferative' type of glomerular lesion, associated with an accumulation of both antibodies in glomeruli. This accumulation occurred even though Sp6 IgM antibodies did not react with B1 IgG3 antibodies and vice versa. A mutant clone of Sp6, T/13microE/3.1, which produces antibodies deficient in C1q binding, produced a similar effect as that of the Sp6 clone, i.e. 'cell-proliferative' lesions. Again the B1 antibodies did not react with T/13microE/3. 1-IgM antibodies and vice versa. We therefore conclude that bystander IgM antibodies contribute to the remodelling of glomerular lesions in situ, following glomerular injury by the nephritogenic antibodies.  相似文献   
24.
25.
To investigate the role of p53 abnormalities in predicting the survival of patients with non-small cell lung cancer (NSCLC), polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and immunohistochemical analyses were performed on 74 and 67 tumor samples, respectively, from patients with pathological stage I-IIIa NSCLC. An abnormally migrating SSCP band was observed in 21 of 74 (28%) tumor specimens. DNA sequence analysis revealed 23 intragenic mutations including 3 small deletions and 20 point mutations. Immunohistochemical analysis using the DO-7 monoclonal antibody showed abnormal expression of p53 in 27 of 67 (40%) patients. The concordance rate between immunohistochemical and PCRSSCP analyses was 73% (49/67) in this study. Univariate and multivariate analyses demonstrated that abnormal expression of p53 may be associated with prolonged survival (p=0.0997 and 0.0099, respectively). In contrast, no relationship was observed between p53 mutation and overall survival (0.6968). These results suggest that p53 status and the survival outcome changes between immunohistochemical and mutational analyses in stage I-IIIa NSCLC.  相似文献   
26.
Low-threshold sensory pathways have been suggested to have an important role in the formation and maintenance of sensory abnormalities which are observed after peripheral nerve injury. Fos-like immunoreactive (Fos-LI) neurons are expressed in spinal cord laminae III-IV and the gracile nucleus by electrically stimulating the injured nerves at Abeta strength after sciatic nerve transection in rats. This suggests that the excitability of these neurons is increased by nerve injury. In this study, we investigated which receptors are involved in the regulation of the increased excitability in spinal and gracile nucleus neurons. The sciatic nerve of Sprague-Dawley rats (150 g) was transected 7 days before the experiment day. The rats were administered morphine, muscimol, baclofen, MK-801, CNQX, N(G)-nitro-L-arginine methyl ester hydrochloride (L-NAME) or clonidine i.p., and then electrically stimulated at 0.1 mA to the proximal region to the nerve injury site under urethane anesthesia. Two hours after the stimulation, Fos-LI expression was increased in the spinal cord dorsal horn and the gracile nucleus in control rats. Baclofen inhibited the Fos-LI expression both in the spinal cord and the gracile nucleus. Morphine inhibited only the Fos-LI expression in the posterior cutaneous (PC) nerve territory of laminae I-II, but not in the sciatic nerve (SC) territory, laminae III-IV nor the gracile nucleus. MK-801 had an inhibitory but complicated effect in laminae I-II and the gracile nucleus. The other drugs were not effective on Fos-LI expression. It is suggested that the GABA(B) receptor has a pivotal role in the regulation of Fos-LI expression after electrical stimulation to the injured low-threshold sensory fibers, and other receptors have little effect on the Fos-LI expression.  相似文献   
27.
BACKGROUND: Persistent hypoalbuminemia is a long-term poor prognostic factor in chronic hemodialysis patients. PATIENTS AND METHODS: We investigated the correlation between the degree of peroxidation of erythrocyte membrane lipids, erythrocyte alpha tocopherol content, erythrocyte glutathione peroxidase activity and serum albumin concentration in twelve patients with uremia not undergoing hemodialysis and fifteen patients on maintenance hemodialysis. RESULTS: The glutathione peroxidase activity in erythrocytes was higher in patients of uremia not undergoing hemodialysis than in chronic hemodialysis patients. A significant negative correlation was observed between the erythrocyte alpha tocopherol content and the degree of erythrocyte membrane lipid peroxidation in chronic hemodialysis patients. There was a statistically significant difference in the degree of erythrocyte membrane lipid peroxidation between patients with chronic hemodialysis-associated hypoalbuminemia and chronic hemodialysis patients having normal serum albumin levels. CONCLUSION: This study suggested that serum albumin inhibits peroxidation of erythrocyte membrane lipids and that hemodialysis induces recovery of serum reductivity. We conclude that persistent hypoalbuminemia worsens the serum antioxidant activity in chronic hemodialysis patients and may contribute to increased oxidative cell damage.  相似文献   
28.
Therapeutic drug monitoring (TDM) of theophylline is essential duties at hospital pharmacy in Japan. The relationship between serum concentrations and clinical effects of theophylline has been investigated. The pharmacokinetics of theophylline was determined from the concentration of theophylline in the serum which were calculated on the basis of TDM for patients administered theophylline. The one-compartment model as a pharmacokinetic model was assumed. The relationship between clinical effects of theophylline and the predicted concentrations calculated using population parameters was evaluated. The obtained parameters are ka(h-1) = 0.223, ke(h-1) = 0.047 (1-0.0025.age(y) (p.o.) and 0.076(1-0.0025.age(y)) (d.i.v.), Vd(1/kg) = 0.733 (p.o.) and 0.830 (d.i.v.). The bioavailability is 0.732, and theophylline/aminophylline is 0.846. The model including no serum creatinine as a variational factor was considered to be best. The following three groups were used as a clinical evaluation; effective as theophylline therapy was 43%, no change of the clinical status after administration of theophylline was 42%, and aggravation after administration of theophylline was 15%. There is no relationship between the predicted concentration using parameters of the final model and these three groups. These results suggest that TDM of theophylline should be assessed in terms of clinical effects and also suggests that in should be kept monitoring from the viewpoint of the prevention of toxic effects in the theophylline therapy.  相似文献   
29.
(E)-2-deoxy-2-(fluoromethylene)cytidine (FMdC), one of the most potent inhibitors of ribonucleoside diphosphate reductase, was selected for clinical development because of its novel mechanisms of action, and strong antitumor activity against experimental tumor models. This study was designed to determine the toxicities, maximum-tolerated dose (MTD), and pharmacokinetic profile of FMdC. FMdC was given orally for 5 consecutive days every 3 or 4 weeks in patients with advanced solid tumors. The starting dose was 8 mg/m2/day. Pharmacokinetic studies were carried out on days 1 through 5 of the first cycle. Ten patients with non-small cell lung cancer received 15 courses of FMdC at doses which were de-escalated from 8 mg/m2/day to 2 mg/m2/day because of unexpected severe toxicities at the starting dose level. Neutropenia was the dose-limiting toxicity. Thrombocytopenia and anemia were mild. Flu-like symptoms and fever were the common non-hematologic toxicities. The MTD was 4 mg/m2/day, since four of six patients developed grade 3–4 neutropenia. At the 4 mg/m2/day dose level, the mean terminal half-life, maximum plasma concentration (Cmax), plasma clearance, and mean residence time on day 1 were 3.20 h, 15.8 ng/ml, 2.91 l/h/kg, and 4.03 h, respectively. The recommended dose for phase II studies with this schedule is also 4 mg/m2/day for 5 days. Further investigations are necessary to establish optimal dosing schedules and routes for the administration of FMdC.  相似文献   
30.
A 79-year-old female presented with cavernous sinus hemangioma manifesting as double vision due to right oculomotor and trochlear nerve pareses. Computed tomography and magnetic resonance imaging revealed bony erosion and a right cavernous sinus tumor with "tail sign" after contrast medium administration. Thallium-201 (201Tl) single photon emission computed tomography (SPECT) showed low uptake within the tumor, and technetium-99m-human serum albumin-diethylenetriaminepenta-acetic acid SPECT disclosed high uptake within the tumor. 201Tl SPECT usually shows very high uptake in meningiomas and malignant tumors, so the tumor was considered to be an unrelated benign tumor. The patient underwent partial resection of the tumor. Histological examination of the specimen confirmed cavernous hemangioma. The oculomotor nerve paresis partially improved. Gamma knife radiosurgery was carried out 4 months after the operation. The tumor markedly shrank with full recovery of extraocular movement 6 months after radiosurgery. SPECT is useful for distinguishing cavernous sinus hemangiomas from other cavernous tumors. Radiosurgery should be performed after partial resection or biopsy for cavernous sinus hemangiomas and may be the initial treatment for patients with small cavernous sinus hemangioma if the diagnosis can be established based on neuroimaging.  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