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   3654篇
  免费   226篇
  国内免费   7篇
耳鼻咽喉   35篇
儿科学   145篇
妇产科学   50篇
基础医学   345篇
口腔科学   75篇
临床医学   399篇
内科学   886篇
皮肤病学   82篇
神经病学   279篇
特种医学   61篇
外国民族医学   1篇
外科学   670篇
综合类   54篇
一般理论   1篇
预防医学   260篇
眼科学   41篇
药学   280篇
中国医学   27篇
肿瘤学   196篇
  2023年   43篇
  2022年   82篇
  2021年   167篇
  2020年   81篇
  2019年   123篇
  2018年   149篇
  2017年   97篇
  2016年   104篇
  2015年   114篇
  2014年   145篇
  2013年   186篇
  2012年   286篇
  2011年   270篇
  2010年   153篇
  2009年   121篇
  2008年   218篇
  2007年   178篇
  2006年   133篇
  2005年   160篇
  2004年   167篇
  2003年   117篇
  2002年   124篇
  2001年   50篇
  2000年   75篇
  1999年   75篇
  1998年   22篇
  1997年   11篇
  1996年   8篇
  1995年   8篇
  1994年   7篇
  1992年   27篇
  1991年   27篇
  1990年   31篇
  1989年   29篇
  1988年   28篇
  1987年   37篇
  1986年   31篇
  1985年   25篇
  1984年   26篇
  1983年   10篇
  1982年   9篇
  1981年   13篇
  1978年   12篇
  1977年   11篇
  1974年   12篇
  1973年   9篇
  1972年   8篇
  1971年   6篇
  1970年   6篇
  1966年   11篇
排序方式: 共有3887条查询结果,搜索用时 343 毫秒
11.
We analyzed the characteristics of the inflammatory response occurring in blood during pulmonary infections in human immunodeficiency virus (HIV)-infected patients. A prospective study of consecutive hospital admissions of HIV-infected patients with new-onset radiologic pulmonary infiltrates was carried out in a tertiary university hospital from April 1998 to May 2001. Plasma cyclic AMP receptor protein (CRP), interleukin 1beta (IL-1beta), IL-6, IL-8, IL-10, and tumor necrosis factor alpha (TNF-alpha) levels were determined at the time of admission and 4, 5, and 6 days later. Patients were included in a protocol addressed to study etiology and outcome of disease. A total of 249 episodes of infection were included, with the main diagnoses being bacterial pneumonia (BP) (118 episodes), Pneumocystis carinii pneumonia (PCP) (41 episodes), and mycobacteriosis (36 episodes). For these three patient groups, at the time of admission the median CRP and cytokine levels were as follows: CRP, 10.2, 3.8 and 5 mg/dl, respectively (P = 0.0001); IL-8, 19, 3, and 2.9 pg/ml (P = 0.045); and TNF-alpha, 46.4, 44, and 75 pg/ml, respectively (P = 0.029). There were no significant differences in levels of IL-1beta, IL-6, or IL-10 among the patient groups. A total of 23 patients died. At the time of admission, HIV-infected patients with BP had higher plasma CRP and IL-8 levels than did PCP and mycobacteriosis patients. TNF-alpha levels were higher in patients with mycobacteriosis. An elevated IL-8 level (>61 pg/ml) at the time of admission was an independent factor associated with higher mortality (odds ratio, 12; 95% confidence interval, 1.2 to 235.5).  相似文献   
12.
OBJECTIVES: To analyze the dynamics of both HIV-1-specific CD4 and CD8 T-cell responses during structured treatment interruptions (STIs) in chronically HIV-1-infected (CHI) patients and to correlate them with the viral set point achieved. METHODS: Forty-five early-stage CHI patients who were on highly active antiretroviral therapy (HAART) for at least 1 year and underwent STI were included. Plasma viral load (VL), peripheral blood mononuclear cell (PBMC) lymphoproliferative (LPR) response to HIV p24 protein, and HIV-1 epitope-specific interferon-gammarelease from CD8 T cells were measured over a minimum study period of 2 years. RESULTS: VL set point during final STI was both significantly lower than, and positively correlated to, baseline VL (P < 0.0001: mean VL reduction 0.77 log10, and r = 0.42, P = 0.004, respectively). CD4 LPRs to p24 increased significantly (P = 0.001) between day 0 of the first STI cycle and 4th STI but decreased thereafter. VL set point during final STI was significantly and negatively correlated with LPRs to p24 at both 2nd STI and 4th STI. Nevertheless, at week 52, 12 weeks after the end of the last STI, LPRs were weak and transient in all patients and were not correlated with VL set point. Moreover, the magnitude and breadth of HIV-1-specific CD8 T-cell responses increased significantly (P < 0.0001) between day 0 and week 52. The largest increases occurred during the final STI. Even though VL reached set point by week 12 of the final STI, HIV-1-specific CD8 T-cell responses did not stabilize but rather increased until the end of the follow-up and did not correlate with plasma VL (r = 0.01, P = 0.88). CONCLUSIONS: STIs do not lead to control of viral replication in CHI patients, probably due to the fact that boosted CTL responses lack strong and durable helper T-cell responses. To reset the VL set point, new approaches that effectively augment and preserve helper T-cell responses should be investigated.  相似文献   
13.
We analyzed the characteristics of the inflammatory response occurring in blood during pulmonary infections in human immunodeficiency virus (HIV)-infected patients. A prospective study of consecutive hospital admissions of HIV-infected patients with new-onset radiologic pulmonary infiltrates was carried out in a tertiary university hospital from April 1998 to May 2001. Plasma cyclic AMP receptor protein (CRP), interleukin 1β (IL-1β), IL-6, IL-8, IL-10, and tumor necrosis factor alpha (TNF-α) levels were determined at the time of admission and 4, 5, and 6 days later. Patients were included in a protocol addressed to study etiology and outcome of disease. A total of 249 episodes of infection were included, with the main diagnoses being bacterial pneumonia (BP) (118 episodes), Pneumocystis carinii pneumonia (PCP) (41 episodes), and mycobacteriosis (36 episodes). For these three patient groups, at the time of admission the median CRP and cytokine levels were as follows: CRP, 10.2, 3.8 and 5 mg/dl, respectively (P = 0.0001); IL-8, 19, 3, and 2.9 pg/ml (P = 0.045); and TNF-α, 46.4, 44, and 75 pg/ml, respectively (P = 0.029). There were no significant differences in levels of IL-1β, IL-6, or IL-10 among the patient groups. A total of 23 patients died. At the time of admission, HIV-infected patients with BP had higher plasma CRP and IL-8 levels than did PCP and mycobacteriosis patients. TNF-α levels were higher in patients with mycobacteriosis. An elevated IL-8 level (>61 pg/ml) at the time of admission was an independent factor associated with higher mortality (odds ratio, 12; 95% confidence interval, 1.2 to 235.5).  相似文献   
14.
Co-infection by human immunodeficiency virus and hepatitis B and C viruses is quite common because they share similar routes of transmission. The introduction of highly active antiretroviral therapy has significantly improved the life expectancy of HIV-infected patients in the last few years. However, chronic viral hepatitis represents an emerging cause of morbidity and mortality in this population, either as a result of end-stage liver disease or as a consequence of hepatotoxicity induced by antiretroviral drugs. The main goal of the Consensus Conference was to establish specific recommendations for the management of chronic viral hepatitis B and C in HIV-infected patients. The role of orthotopic liver transplantation for co-infected individuals with end-stage liver disease was also assessed.  相似文献   
15.
The aim of this study was to determine the relationships between bone mineral density (BMD) and blood pressure in 214 men, age 20–76. BMD measurements were done by dual X‐ray absorptiometry using a Lunar DPXMD densitometer at the lumbar spine (L2–L4) and different femoral regions. Systolic (SBP) and diastolic (DBP) blood pressure were measured using an MPC‐350 sphygmomanometer. Physicians gathered demographic data and participants' dietary intake of calcium were determined by using food frequency questionnaires. After adjusting for age, body mass index, dietary calcium, and exercise history, multiple linear regression models showed that DBP was negatively related to femoral neck BMD (β = ?0.145, P = 0.032) and just shy of significant association with femoral neck BMC (β = ?0.114, P = 0.079). SBP was correlated with femoral neck (r = ?0.171, P = 0.012) and Ward's (r = ?0.186, P = 0.006) BMD but not after adjusting for possible confounders. Further studies are needed to determine whether elevated blood pressure is causally related to the development of low bone mass. Am. J. Hum. Biol. 16:168–171, 2004. © 2004 Wiley‐Liss, Inc.  相似文献   
16.
Fenclorac (a,m-dichloro-p-cyclohexylphenylacetic acid, diethylammonium salt) is a potent nonsteroidal anti-inflammatory agent with significant analgesic and antipyretic activity. Fenclorac had an ED50 of 7.9 mg/kg in the carrageenan paw edema assay and had a duration of action of 18–22 hours. Comparative tests in the carrageenan paw edema assay in the rat indicated that the potency of fenclorac was 13 times that of aspirin, 3.4 times phenylbutazone, 3 times ibuprofen and 0.3 times indomethacin. Fenclorac was less potent than indomethacin, but more potent than phenylbutazone or aspirin in treatment of developing or established adjuvant arthritis. The anti-inflammatory effectiveness of fenclorac did not depend upon the integrity of the adrenopituitary axis and was not affected by the route of administration or sex of the test animal. Fenclorac was 77 times more potent than aspirin and more than twice as potent as indomethacin in reducing fever in rats rendered hyperthermic with brewer's yeast. Fenclorac did not affect normal body temperatures. Fenclorac did not interfere with cellular immune mechanisms as measured by its lack of effectiveness in experimental allergic encephalomyelitis. Antinociceptive testing indicated that fenclorac had peripheral but not central analgesic activity. Fenclorac had an acute oral LD50 in rats and mice of 285 and 430 mg/kg, respectively. The acute gastric lesion UD50 for fenclorac was 7 mg/kg in the fasted rat. Studies using51Cr-tagged erythrocytes indicated that fenclorac did not produce significant fecal blood loss in the rat at twice the therapeutic ED50 dose for up to 12 days after dosing. Extensive and prolonged fecal blood loss was observed with a corresponding dose of indomethacin for up to nine days after administration. Comparison of the antiinflammatory pharmacology, Therapeutic Ratio and the data obtained from the51Cr-fecal blood loss studies indicated that fenclorac was well tolerated after acute or subacute administration to the rat.  相似文献   
17.
Though many hearing impairment genes have been identified, only a few of these genes have been screened in population studies. For this study, 168 Pakistani families with autosomal recessive hearing impairment not due to mutations in the GJB2 (Cx26) gene underwent a genome scan. Two-point and multipoint parametric linkage analyses were carried out. Twelve families had two-point or multipoint LOD scores of 1.4 or greater within the transmembrane cochlear expressed gene 1 (TMC1) region and were subjected to further screening with direct DNA sequencing. Five novel putatively functional non-synonymous sequence variants, c.830A>G (p.Y277C), c.1114G>A (p.V372M), c.1334G>A (p.R445H), c.2004T>G (p.S668R), and c.2035G>A (p.E679K), were found to segregate within seven families, but were not observed in 234 Pakistani control chromosomes. The variants c.830A>G (p.Y277C), c.1114G>A (p.V372M), and c.1334G>A (p.R445H) occurred at highly conserved regions and were predicted to lie within hydrophobic transmembrane domains, while non-synonymous variants c.2004T>G (p.S668R) and c.2035G>A (p.E679K) occurred in extracellular regions that were not highly conserved. There is evidence that the c.2004T>G (p.S668R) variant may have occurred at a phosphorylation site. One family has the known splice site mutation c.536 -8T>A. The prevalence of non-syndromic hearing impairment due to TMC1 in this Pakistani population is 4.4% (95%CI: 1.9, 8.6%). The TMC1 protein might have an important function in K(+) channels of inner hair cells, which would be consistent with the hypothetical structure of protein domains in which sequence variants were identified.  相似文献   
18.

This paper analyzes the impact of mental health treatment on suicide attempts. While prior work demonstrates the effectiveness of mental health treatment at reducing suicide risk, few studies examine nationally representative populations or use broad measures of access to mental health services. A methodological problem can arise in studies of mental health treatment and suicidal behavior because a suicide attempt can result in the use of more mental health services. Using nationally representative survey data combined with national estimates of provider availability, this paper employs a methodological correction to address that potential problem of reverse causation. This paper uses measures of the density of health care providers in an area as statistical instruments for use of mental health treatment in an analysis of the impact of mental health treatment on suicide attempts. This study finds that mental health treatment significantly reduces suicide attempts.

  相似文献   
19.
BackgroundIn the context of the opioid epidemic, a limited but growing body of literature has found state medical marijuana laws (MMLs) to be associated with lower levels of opioid prescribing. However, robust evidence linking state MMLs with individual-level opioid-related outcomes is lacking, particularly among women. This finding is especially true for pregnant and parenting women, who have been disproportionately affected by the opioid crisis.MethodsUsing data drawn from the 2002–2014 National Survey on Drug Use and Heath, the study uses a difference-in-differences estimation strategy to compare opioid-related outcomes (opioid misuse initiation, opioid misuse in the past month and past year, and opioid use disorder) among all women, pregnant women, and parenting women in states with and without MMLs (before and after implementation). The study also investigates the impact of MMLs on marijuana use and marijuana use disorder.ResultsThe findings indicate that MMLs were not associated with opioid misuse, opioid misuse initiation, or opioid use disorder among all women, pregnant women, and parenting women. These laws were, however, positively correlated with marijuana use and marijuana use disorder among all women and women with children. In addition, MMLs were associated with an increase in the frequency of opioid misuse for pregnant women and a decrease in the frequency of opioid misuse for parenting women.ConclusionsThis finding suggests that, although medical marijuana may be viewed by some as a substitute for opioid analgesics, MMLs may not be an effective policy tool to tackle the opioid epidemic among women, especially pregnant and parenting women.  相似文献   
20.
BackgroundSquare knots can be difficult to construct in deep body cavities. The reversing half-hitch alternating post (RHAP) surgical knot has noninferior tensile strength and performance characteristics in deep body cavities. We compared the enterotomy repairs of novice learners in simulated deep body cavities using RHAP versus square knots after proficiency-based training.MethodsUndergraduate students were randomized to RHAP (n = 10) or square knot (n = 10) groups and trained to defined proficiency. They then performed hand-sewn enterotomy repairs of cadaveric porcine small bowels on flat surfaces and in simulated deep body cavities. We recorded time to knot-tying proficiency and to enterotomy repair, and burst pressures for the repair.ResultsMean time-to-proficiency in knot tying was equivalent between the RHAP and square knot groups (23 [standard deviation (SD) 3] v. 21 [SD 2] min, p = 0.33). Mean time for enterotomy repair in deep cavities was shorter for the RHAP group (16 [SD 2] min v. 21 [SD 1] min, p = 0.02). Mean burst pressures for enterotomy repair were equivalent on flat surfaces (128 [SD 41] v. 101 [SD 36] mm Hg, p = 0.31), and were significantly higher for the RHAP group in simulated deep body cavities (32 [SD 13] v. 105 [SD 37] mm Hg, p = 0.05).ConclusionThe RHAP knots appear to have superior performance versus square knots when tied in a deep body cavity by novice learners. Future work should focus on demonstrating the clinical relevance and broad utility of the RHAP knot in abdominal surgery. Both knot types should be taught to novice learners.  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