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   94248篇
  免费   8592篇
  国内免费   2718篇
耳鼻咽喉   1258篇
儿科学   1848篇
妇产科学   1510篇
基础医学   6386篇
口腔科学   2046篇
临床医学   14482篇
内科学   11425篇
皮肤病学   2526篇
神经病学   4844篇
特种医学   2242篇
外国民族医学   6篇
外科学   6076篇
综合类   12962篇
现状与发展   4篇
一般理论   3篇
预防医学   14534篇
眼科学   1281篇
药学   10975篇
  265篇
中国医学   6929篇
肿瘤学   3956篇
  2024年   1171篇
  2023年   2035篇
  2022年   3180篇
  2021年   4437篇
  2020年   4408篇
  2019年   3681篇
  2018年   3460篇
  2017年   3805篇
  2016年   3697篇
  2015年   3691篇
  2014年   6622篇
  2013年   7182篇
  2012年   6098篇
  2011年   6168篇
  2010年   4852篇
  2009年   4614篇
  2008年   4639篇
  2007年   4540篇
  2006年   3973篇
  2005年   3391篇
  2004年   2795篇
  2003年   2362篇
  2002年   1896篇
  2001年   1657篇
  2000年   1333篇
  1999年   1183篇
  1998年   920篇
  1997年   898篇
  1996年   774篇
  1995年   754篇
  1994年   632篇
  1993年   520篇
  1992年   545篇
  1991年   441篇
  1990年   360篇
  1989年   366篇
  1988年   333篇
  1987年   308篇
  1986年   241篇
  1985年   276篇
  1984年   223篇
  1983年   171篇
  1982年   190篇
  1981年   151篇
  1980年   125篇
  1979年   96篇
  1978年   80篇
  1977年   64篇
  1976年   49篇
  1975年   38篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Di(2-ethylhexyl) terephthalate (DEHT) is a commercially produced chemical (Kodaflex® DOTP) that is used as a general purpose, low-volatility plasticizer for polyvinyl chloride and other polymeric materials. Less than 30 million kilograms of DEHT are produced annually. DEHT is isomeric with di(2-ethylhexyl) phthalate (DEHP), a nongenotoxic rodent carcinogen whose mode of action has been suggested to derive from its ability to produce hepatocellular proliferation and/or hepatic peroxisome proliferation. Thus it is important to know the behavior of DEHT in genotoxicity assays in order to compare it with that of DEHP and other phthalate ester plasticizers. It is known from previously published studies that rats fed DEHT in the diet at 2,000 mg/kg produce urine that is negative in the Ames Salmonella bacterial mutagenicity assay in the presence and absence of induced rat liver S-9 and in the presence and obsence of β-glucuronidase/aryl sulfatase. Reported here are the results of direct testing of DEHT in the Ames plate incorporation assay, the Chinese hamster ovary/hypoxanthine guanine phosphoribosyl transferase (CHO/HGPRT) in vitro mammalian cell mutagenicity assay, and an in vitro chromosome aberrations assay using CHO cells. The results for mono(ethylhexyl) terephthalate (MEHT), a metabolite of DEHT, in the Ames Salmonella bacterial mutagenicity assay are also presented. All test results for both DEHT and MEHT were found to be negative, and it is therefore concluded that DEHT, like its isomeric relative DEHP, is not genotoxic. © 1994 Wiley-Liss, Inc.  相似文献   
102.
Abstract We investigated factors correlated with abnormal behavior in the elderly residing in a special nursing home (group A) and a psychiatric hospital (group B) using the dementia behavior disturbance scale, the mini mental state examination, the Japanese version of the Philadelphia Geriatric Center morale scale, and the ADL assessment scale. The cognitive function of group B was decreased compared with that of group A, but most activities of daily living (ADL) in the latter group were disrupted compared with those in the former. Only a few categories of ADL correlated with abnormal behavior in group A, whereas cognitive function, quality of life, and most categories of ADL correlated with abnormal behavior in group B. These results suggest that factors correlated with abnormal behavior in the elderly differ within institutions of medical and social welfare systems.  相似文献   
103.
Fenfluramine, an amphetamine derivative used in the treatment of obesity, has been evaluated in vivo in the bone marrow cells of Swiss albino mice using two cytogenetic endpoints for assessing its genotoxic and clastogenic potentials. Concentrations of 0.75, 1.5, 3.0, and 5.0 mg/kg b.w. were administered orally for the study of sister chromatid exchange frequencies and chromosome aberrations (CA). SCE frequencies showed a positive dose response; 1.5 mg/kg being the minimum effective concentration. Fen caused a prolongation of cell cycle at all concentrations. Except for the minimum therapeutic dose (0.75 mg), all other doses (1.5, 3.0, and 5.0 mg) showed a significant increase in the percentage of damaged cells over that of the vehicle control. The degree of clastogenicity was directly proportional to the dosage used and inversely related with the duration of treatment. A gradual reduction of the clastogenic potential was observed after 12 and 24 hr of exposure, indicating that the maximum effect occurs at the middle or late synthetic phase of the cell cycle. This study, probably the first detailed screening of the drug for its genotoxicity, shows that Fen is moderately clastogenic and a DNA damaging agent in vivo.  相似文献   
104.
Men with prostate cancer ( n = 11) were interviewed during an in-patient period at a urological clinic, about their experiences of met and unmet needs from health professionals. Their perception of quality of life and sense of coherence were also assessed. The findings were analysed from a phenemenological-hermeneutic perspective and interpreted within the concept of transition. It was interpreted that objective functional health needs were mostly met by health professionals and subjective existential needs were mostly not met. The analysis revealed patients as passive or active receivers of care. Passive receivers were explicitly and implicitly stating unmet needs, or explicitly stating satisfaction with nursing care at the same time as implicitly contradicting, referring to their needs as bagatelles, unimportant, whereas active receivers talked about their needs explicitly with the staff and did not state implicit unmet needs. This suggests that nurses need to be aware of and have sensitive ears to undertones in statements and actively seek for patients' needs. The most important nursing care areas seemed to be to provide solutions to physical problems together with staff support including information, and acting to increase confidence in staff and staff availability. This encourages patients, wives and families, in co-operation, towards a healthy exit of transition.  相似文献   
105.
目的:探讨直立倾斜试验(HUTT)对心脏神经症的诊断价值。方法:对59例心脏神经症患者,在排除器质性心脏病后行HUTT。结果:43例呈阳性,阳性发生率为72.9%。不同性别间反应类型有显著差异(P<0.05),女性多见血管抑制型(占76.9%)。不同反应类型间终末血压、心率有明显差异(P<0.05)。结论:HUTT可作为心脏神经症有效的辅助诊断方法。  相似文献   
106.
Although tricyclic antidepressant are especially useful in the treatment of chronic pain conditions, most of the work about its mechanism of action has been made on acute pain tests. The present study was aimed at studying the role played by noradrenergic and opioidergic influences on the antinociceptive activity of subchronically administered clomipramine in the formalin test (a tonic pain model) in rats. Clomipramine produced antinociception after 7 days, administration (2.5 mg/kg/day), an effect equivalent to that obtained by acute morphine (5 mg/kg). The antinociceptive effect of clomipramine was inhibited by the following: nonspecific blocking of alpha1-and alpha2-adrenoceptors by phentolamine, specific blocking of alpha1-adrenoceptors by prazosin; stimulation of alpha2 receptors by clonidine; and blocking of the opioid receptors by naloxone. Blocking the alpha2-receptors with yohimbine did not antagonize the effect of clomipramine. These results suggest that clomipramine produces antinociception in this test, partly via the participation of the endogenous opioid system and partly by further activating or potentiating previously activated noradrenergic pathways which are involved in the control of pain information.  相似文献   
107.
The acute effects of protein loading (1.5 g kg-1) on glomerular filtration rate (GFR) and urinary albumin excretion (UAE) were investigated in 23 type-I diabetic patients with no clinical nephropathy, and in 7 healthy subjects (controls). The results were compared with renal morphology data. In controls and in 14 diabetic patients (group 1) GFR increased by 27 and 37%, respectively, corresponding to normal renal reserve, but in 9 patients (group 2) GFR decreased by 20%, indicating the absence of a renal reserve. Microalbuminuria was found in none of the patients in group 1 and in 50% of patients in group 2. Two hours after the load UAE increased in all groups, but the increase was most marked in group 2, despite the fall in GFR. The two groups of patients did not differ with regard to the duration and control of diabetes, but differed markedly in terms of baseline GFR (131 vs. 195 ml min-1, P less than 0.01, in groups 1 and 2, respectively). Renal morphology showed minimal non-specific glomerular injury in group 1, and signs of glomerulosclerosis in group 2. We conclude that the impaired renal response to protein load precedes other subclinical manifestations of diabetic renal injury, and may be useful in the diagnosis of latent diabetic nephropathy.  相似文献   
108.
本文采用中和试验、沉降反应和解离试验对135例已知血型人精液中ABH血型物质的分泌强度进行了检验,并将其分为强、中、弱三型。这对区别个人血型物质含量及性犯罪的法医学鉴定均有重要意义。并证明了AB型人精液中A、B血型物质含量不均等现象,并且绝大多数人B型物质高于A型物质。  相似文献   
109.
110.
The purposes of the present study were to compare the cardiovascular response patterns evoked by three versions of the cold pressor test (either forehead stimulation or hand or foot immersion) and to determine the reproducibility of the responses over a 2-week interval. Blood pressure, heart rate, stroke volume, cardiac output, total peripheral resistance, and systolic time intervals were obtained during rest and during the cold pressor test in 42 young men. Across conditions, the pressor response was supported by peripheral resistance increases with concomitant stroke volume decreases. Although the response panerns were generally similar across sites, exceptions were apparent for heart rate. Forehead stimulation was characterized by no significant change in heart rate, whereas limb (hand or foot) immersion was associated with significant heart rate acceleration. The responses elicited by the three cold pressor test conditions were reliable and showed little evidence of attenuation over the test-retest interval.  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