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   30895篇
  免费   2732篇
  国内免费   1023篇
耳鼻咽喉   299篇
儿科学   561篇
妇产科学   515篇
基础医学   4724篇
口腔科学   930篇
临床医学   2709篇
内科学   5727篇
皮肤病学   594篇
神经病学   2652篇
特种医学   1149篇
外国民族医学   2篇
外科学   4151篇
综合类   2390篇
一般理论   8篇
预防医学   1867篇
眼科学   680篇
药学   2886篇
中国医学   392篇
肿瘤学   2414篇
  2023年   93篇
  2022年   193篇
  2021年   421篇
  2020年   250篇
  2019年   383篇
  2018年   655篇
  2017年   528篇
  2016年   523篇
  2015年   613篇
  2014年   779篇
  2013年   1003篇
  2012年   1358篇
  2011年   1350篇
  2010年   854篇
  2009年   722篇
  2008年   1215篇
  2007年   1328篇
  2006年   1204篇
  2005年   1008篇
  2004年   905篇
  2003年   828篇
  2002年   702篇
  2001年   2288篇
  2000年   2194篇
  1999年   1811篇
  1998年   672篇
  1997年   452篇
  1996年   316篇
  1995年   277篇
  1994年   241篇
  1993年   223篇
  1992年   1000篇
  1991年   890篇
  1990年   796篇
  1989年   883篇
  1988年   802篇
  1987年   741篇
  1986年   690篇
  1985年   608篇
  1984年   383篇
  1983年   318篇
  1982年   182篇
  1981年   138篇
  1980年   119篇
  1979年   203篇
  1978年   84篇
  1974年   84篇
  1973年   93篇
  1972年   93篇
  1971年   94篇
排序方式: 共有10000条查询结果,搜索用时 575 毫秒
991.
992.
A third of patients with multiple myeloma (MM) have a preceding diagnosis of plasma cell proliferative disorder (PCPD), mostly monoclonal gammopathy of undetermined significance (MGUS), smoldering MM (SMM) or plasmacytoma. While autologous stem cell transplantation (SCT) improves survival in MM, it is not clear if patients with preceding PCPD have a different outcome. We identified 151 patients with preceding PCPD from among 804 patients undergoing SCT, and their outcomes were compared. The response rates, including complete responses, were similar between the groups. Patients with a preceding diagnosis of MGUS had longer time to progression (TTP; 27·5 months vs. 17·2 months, P  = 0·01), and longer overall survival (OS) from transplant (80·2 months vs. 48·3 months, P  = 0·03) compared to those with de novo myeloma. However no differences were seen among those with a preceding diagnosis of SMM or plasmacytoma in terms of TTP or OS from transplant when compared to those with de novo myeloma. Multivariate analysis indicated that the presence of MGUS prior to myeloma was prognostic for post-transplant relapse independent of other known risk factors. Patients with pre-existing MGUS prior to myeloma diagnosis have a better outcome following HDT, reflecting more indolent disease and a favourable biology than those presenting with de novo myeloma.  相似文献   
993.
Abstract
Background:  Ischaemic nephropathy is currently a major public health issue in atherosclerotic populations. Although atherosclerotic cardiovascular disease in Asia has reached epidemic proportions over the last two decades, there is little published data on the prevalence of atherosclerotic renal artery stenosis (ARAS) in Oriental subjects. Because ARAS may be clinically silent until end-stage renal failure sets in, it is important to identify patients with significant but clinically unsuspected ARAS. ARAS and coronary artery disease (CAD) often coexist.
Aims:  The purpose of the present study was to evaluate the prevalence and predictors of ARAS among Chinese patients with CAD.
Methods:  A total of 230 consecutive Chinese patients with CAD confirmed by coronary angiography underwent an abdominal aortogram in the same sitting to screen for ARAS. Patient demographics and comorbid­ities were analysed for any association with ARAS.
Results:  A total of 34 (14.8%) patients was found to have significant ARAS. Age and multivessel CAD were independent predictors of ARAS. Hypertension, renal insufficiency, extracranial cerebrovascular disease and female gender were also associated with a higher risk of ARAS but did not independently predict ARAS.
Conclusion:  Clinically silent yet angiographically significant ARAS is common among CAD patients. The prevalence and predictors of ARAS among Chinese patients with CAD are similar to those reported for Caucasian subjects. Underlying ARAS should be suspected in CAD patients with such comorbidities as hypertension, renal insufficiency, extracranial cerebrovascular disease, and more so in the elderly and those with multivessel disease. (Intern Med J 2003; 33: 280−285)  相似文献   
994.
995.
SETTING: Mycobacteria growth in media with the addition of inhibitory substances has been used in species identification. Growth of the Mycobacterium tuberculosis complex (MTC) is inhibited by rho-nitrobenzoic acid (PNB), whereas non-tuberculous mycobacteria (NTM) are resistant. OBJECTIVE: To develop a rapid PNB test using the automated BACTEC MGIT960 system and to evaluate its usefulness in the screening of mycobacterial isolates. DESIGN: PNB tests were performed in 93 MTC strains and 61 NTM strains from the Instituto Adolfo Lutz Culture Collection. PNB was added to L?wenstein-Jensen (LJ) medium and to BACTEC MGIT960 medium. RESULTS: The MTC strains were all PNB-susceptible, confirming the original identification. Among 10 NTM species, all were found to be resistant to PNB, except for one strain of M. kansasii and another of M. marinum. The median time to obtain presumptive identification of MTC by inhibition test in the BACTEC MGIT960 system was 6.3 days and for NTM it was 2.5 days. The presumptive identification of MTC in LJ was mostly obtained after day 20. CONCLUSION: The key finding of this analysis was the possibility of combining the traditionally accepted method proposed by Tsukamura and Tsukamura in 1964 with the modern, safe and rapid BACTEC MGIT960 methodology.  相似文献   
996.
We surveyed the prevalence of parasitic infections in the mountainous province of Hoa Binh, north-west Vietnam, involving 526 households of six ethnic groups: Muong, Kinh, Dao, Thai, Tay and Hmong. Eggs or cysts of at least one parasite species were detected in 88% of stool samples (n = 2522). Prevalences of nematodes were high among all ethnic groups: hookworm (52%), Trichuris trichiura (50%) and Ascaris lumbricoides (45%). Ascaris infection appeared to be lower in households owning a latrine, was highest among children and decreased with age. Prevalence of hookworm rose during childhood, remained high until old age, was highest among adult women, but was not linked to anaemia. Eggs of Chlonorchis spp. were found in 126 (5%) individuals (of the Muong, Kinh or Thai groups only). Chlonorchiasis increased with age and was highest among adult men. Taenia eggs were found in three individuals (0.1%). Giardia lamblia was found in all districts and among all groups and the prevalence of infection was estimated at 3%.  相似文献   
997.
Immunopathogenesis of inflammatory bowel disease   总被引:7,自引:1,他引:7  
Crohn's disease and ulcerative colitis are chronic relapsing immune mediated disorders that results from an aberrant response to gut luminal antigen in genetically susceptible host. The adaptive immune response that is then triggered was widely considered to be a T-helper-1 mediated condition in Crohn's disease and T-helpero2 mediated condition in ulcerative colitis. Recent studies in animal models, genome wide association, and basic science has provided important insights in in the immunopathogenesis of inflammatory bowel disease, one of which was the characterization of the interleukin-23/Th-17 axis.  相似文献   
998.
999.
Serum triglyceride (TG) and high-density lipoprotein cholesterol (HDL-C) concentrations are inversely correlated and mechanistically linked by means of lipid transfer activities. Phospholipid transfer activity (PLTA) moves phospholipids among serum lipoproteins; cholesteryl ester transfer activity (CETA), which exchanges cholesteryl esters (CE) and TG among lipoproteins, is stimulated by nonesterified fatty acids (NEFA). The aims of this study were (a) to develop a quantitative model that correlates the neutral lipid (NL = CE + TG) compositions of HDL and LDL with serum TG concentration; (b) identify the serum lipid determinants of CETA and PLTA, and; (c) identify the effects of serum TG reductions on the neutral lipid compositions of HDL and LDL, serum NEFA concentrations, and on PLTA and CETA. These aims were addressed in 40 hypertriglyceridemic subjects before and after treatment with an 85% concentrate of omega-3 fatty acids (Omacor) and in 16 untreated normolipidemic subjects. In vivo, the NL compositions of LDL and HDL were described by a mathematical model having the form of adsorption isotherms: HDL - (TG/NL) = (0.90 +/- 0.07) serum TG/(7.0 +/- 1.2 mmol/l + serum TG) and LDL - (TG/NL) = (0.65 +/- 0.08) serum TG/(4.9 +/- 1.5 mmol/l + serum TG). Reduction of serum TG was associated with reductions in HDL - (TG/NL), serum NEFA concentration, and serum CETA but not PLTA. These data suggest that both hypertriglyceridemia and the attendant elevated serum CETA but not PLTA are determinants of HDL and LDL composition and structure and that serum TG concentrations are good predictors of the NL compositions of HDL and LDL.  相似文献   
1000.
TNF-α induced, in a time and dose-dependent fashion, cell-cell dissociation (dyscohesion) of endometrial epithelial cells. Within the time frame that dyscohesion was induced, TNF-α, in a dose-dependent fashion, reduced filamentous (F) actin and resulted in the loss of F-actin from the intercellular boundaries. Loss of F-actin mediated by TNF-α was not due to a reduction in the overall amount of actin or its β-isoform. Two proteins, Rho and Rho guanine nucleotide dissociation inhibitor (Rho-GDI), have been implicated in the regulation of organization of actin cytoskeleton. The reduced level of F-actin was not associated with altered expression of Rho protein, however, it was associated with an increase in the amount of Rho available for ribosylationin vitro by the C3 exoenzyme of Clostridium botulinum. The amount of Rho-GDI protein did not change after treatment with TNF-α suggesting that elevated expression of this protein is not responsible for the disassembly of actin filaments. These findings show that TNF-α induces dyscohesion. Dyscohesion induced by this cytokine is associated with perturbation of the actin cytoskeleton which may be due to the regulatory role of TNF-α on Rho.  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