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   17913篇
  免费   1500篇
  国内免费   48篇
耳鼻咽喉   118篇
儿科学   649篇
妇产科学   352篇
基础医学   2397篇
口腔科学   140篇
临床医学   2299篇
内科学   3584篇
皮肤病学   322篇
神经病学   1919篇
特种医学   507篇
外科学   2149篇
综合类   344篇
一般理论   22篇
预防医学   1985篇
眼科学   212篇
药学   1182篇
中国医学   20篇
肿瘤学   1260篇
  2024年   32篇
  2023年   252篇
  2022年   311篇
  2021年   625篇
  2020年   408篇
  2019年   684篇
  2018年   689篇
  2017年   465篇
  2016年   519篇
  2015年   500篇
  2014年   668篇
  2013年   937篇
  2012年   1465篇
  2011年   1426篇
  2010年   721篇
  2009年   657篇
  2008年   1038篇
  2007年   1082篇
  2006年   1030篇
  2005年   946篇
  2004年   804篇
  2003年   798篇
  2002年   746篇
  2001年   235篇
  2000年   220篇
  1999年   200篇
  1998年   147篇
  1997年   144篇
  1996年   101篇
  1995年   110篇
  1994年   66篇
  1993年   78篇
  1992年   109篇
  1991年   107篇
  1990年   77篇
  1989年   98篇
  1988年   73篇
  1987年   77篇
  1986年   65篇
  1985年   72篇
  1984年   66篇
  1983年   59篇
  1982年   38篇
  1981年   45篇
  1980年   33篇
  1979年   36篇
  1978年   33篇
  1977年   37篇
  1976年   32篇
  1971年   39篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
We undertook a prospective study of standard peripheral pulse oximetry versus a modified pulse oximeter probe applied to the tongue in order to determine the efficacy of this alternative monitoring site in children with thermal injuries. Ten patients with a mean age (± SD) of 7.5 ± 4.5 yr were studied on 15 occasions. The mean weight +- SD) was 31.4+- 13.7 kg and percent surface area burn (± SD) was 56+- 21%. A total of 1,992 min of anaesthesia time was monitored. Both sites functioned simultaneously 47% of the time; the lingual but not the peripheral site functioned 28% of the time and only the peripheral site and not the lingual functioned 22% of the time. Neither site functioned 3% of the time. The tongue oximeter provided 563 min more monitoring time than the peripheral sites. The tongue oximeter also functioned in children with peripheral vasoconstriction when the peripheral sensor failed and was less susceptible to electrocautery interference. The tongue oximeter is a reasonable adjunct but not a substitute for peripheral oximetry since its application is limited to paralyzed, intubated patients.  相似文献   
62.
The intestinal absorption of molybdenum in healthy human volunteers has been measured by simultaneous oral and intravenous administration of the stable isotopes 95Mo and 96Mo, and the results were analysed using the convolution integral technique. The results showed that molybdenum ingested in liquid form was rapidly and totally absorbed into the circulation under ordinary intake regimes. The rates and extent of absorption were lower for composite meals, and also for increasing levels of administration. This information can be helpful in the application of the new ICRP model of the human alimentary tract.  相似文献   
63.
64.
To determine the influence of infiltrating lobular histology on local tumor control, the authors studied 49 patients with Stages I and II infiltrating lobular breast carcinoma treated by limited excision of the tumor and radiotherapy between 1968 and 1981 (median follow-up, 75 months). Results were compared with those in 561 cases of infiltrating ductal carcinoma similarly treated during the same period. The 5-year actuarial risk of local recurrence was similar for patients with infiltrating lobular or ductal carcinoma when the latter was evaluated as a single group (12% versus 11%). However, the 12% 5-year actuarial local recurrence risk for patients with infiltrating lobular carcinoma was intermediate between that for patients with infiltrating ductal carcinomas with an extensive intraductal component (23%) and those without an extensive intraductal component (5%). The pattern of recurrence in the breast was similar in the infiltrating lobular and ductal groups. All recurrences in patients with infiltrating lobular carcinoma and 80% of recurrences in the infiltrating ductal group occurred in the vicinity of the primary tumor (P = not significant). None of the clinical or morphologic features examined significantly influenced the risk of local recurrence in patients with infiltrating lobular carcinoma. The authors conclude that combined conservative surgery and radiotherapy appear to be a reasonable treatment option for patients with infiltrating lobular carcinoma, but further follow-up will be required to confirm these results.  相似文献   
65.
Twelve patients with frequent ventricular premature depolarizations (VPDs) received amiodarone, 600 mg/day, for up to 8 weeks. On days 0, 1, 4, 8, 15, 22, 36, and 57 of treatment, 24-hour ambulatory ECGs were obtained, and multiple blood samples were taken for determination of amiodarone and desethylamiodarone plasma concentrations. All patients had at least 75% suppression of VPDs. The mean duration of therapy before the onset of antiarrhythmic effect was 13.2 days (range 1 to 36 days). Trough amiodarone and desethylamiodarone plasma concentrations at the time of onset of antiarrhythmic effect were 0.86 +/- 0.48 mg/L and 0.23 +/- 0.15 mg/L, respectively. Sixty-seven percent of patients responded at amiodarone concentrations below 1.0 mg/L. For each patient there was a progressive decrease in frequency of VPDs as both amiodarone and desethylamiodarone concentrations increased. Regression modeling indicated that both amiodarone and desethylamiodarone plasma concentrations explained significant variability in the frequency of VPDs, and amiodarone and desethylamiodarone plasma concentrations were highly correlated with each other. There was a trend for desethylamiodarone to explain more variability in frequency of VPDs than amiodarone.  相似文献   
66.
Monocyte chemoattractant protein 1 (MCP-1) is a member of the chemokine family of cytokines that mediate leukocyte chemotaxis. The potent and specific activation of monocytes by MCP-1 may mediate the monocytic infiltration of tissues in atherosclerosis and other inflammatory diseases. We have isolated cDNAs that encode two MCP-1-specific receptors with alternatively spliced carboxyl tails. Expression of the receptors in Xenopus oocytes conferred robust mobilization of intracellular calcium in response to nanomolar concentrations of MCP-1 but not to related chemokines. The MCP-1 receptors are most closely related to the receptor for the chemokines macrophage inflammatory protein 1 alpha and RANTES (regulated on activation, normal T expressed and secreted). The identification of the MCP-1 receptor and cloning of two distinct isoforms provide powerful tools for understanding the specificity and signaling mechanisms of this important chemokine.  相似文献   
67.
IL-12 and IL-23: master regulators of innate and adaptive immunity   总被引:27,自引:0,他引:27  
Summary: Initiation of an effective immune response requires close interactions between innate and adaptive immunity. Recent advances in the field of cytokine biology have led to an increased understanding of how myeloid cell‐derived factors regulate the immune system to protect the host from infections and prevent tumor development. In this review, we focus on the function of interleukin (IL)‐23, a new member of the IL‐12 family of regulatory cytokines produced by activated macrophages and dendritic cells. We propose that IL‐12 and IL‐23 promote two distinct immunological pathways that have separate but complementary functions. IL‐12 is required for antimicrobial responses to intracellular pathogens, whereas IL‐23 is likely to be important for the recruitment and activation of a range of inflammatory cells that is required for the induction of chronic inflammation and granuloma formation. These two cytokines work in concert to regulate cellular immune responses critical for host defense and tumor suppression.  相似文献   
68.
Clinically, inflammatory pain is far more persistent than that typically modelled pre-clinically, with the majority of animal models focussing on short-term effects of the inflammatory pain response. The large attrition rate of compounds in the clinic which show pre-clinical efficacy suggests the need for novel models of, or approaches to, chronic inflammatory pain if novel mechanisms are to make it to the market. A model in which a more chronic inflammatory hypersensitivity phenotype is profiled may allow for a more clinically predictive tool. The aims of these studies were to characterise and validate a chronic model of inflammatory pain. We have shown that injection of a large volume of adjuvant to the intra-articular space of the rat knee results in a prolonged inflammatory pain response, compared to the response in an acute adjuvant model. Additionally, this model also results in a hypersensitive state in the presence and absence of inflammation. A range of clinically effective analgesics demonstrate activity in this chronic model, including morphine (3mg/kg, t.i.d.), dexamethasone (1mg/kg, b.i.d.), ibuprofen (30mg/kg, t.i.d.), etoricoxib (5mg/kg, b.i.d.) and rofecoxib (0.3-10mg/kg, b.i.d.). A further aim was to exemplify the utility of this chronic model over the more acute intra-plantar adjuvant model using two novel therapeutic approaches; NR2B selective NMDA receptor antagonism and iNOS inhibition. Our data shows that different effects were observed with these therapies when comparing the acute model with the model of chronic inflammatory joint pain. These data suggest that the chronic model may be more relevant to identifying mechanisms for the treatment of chronic inflammatory pain states in the clinic.  相似文献   
69.
Background: The slitlamp can be used to estimate the anterior chamber depth (ACD). The length of a slit object is increased until the corneal and iris/lens images appear to just touch. Multiplying the just‐touching‐slit‐length (JTSL) by a conversion factor gives an estimate of the ACD as measured by ultrasonography. The purpose of this study was to determine if central corneal thickness (CCT) affects the accuracy of this technique. Methods: The ACD of 50 subjects was measured by A‐scan ultrasonography and estimated by the slitlamp technique. CCT was measured by ultrasonic pachometry. The refractive error was determined subjectively. Results: The average ultrasonographic ACD for all subjects was 3.32 ± 0.65 mm. The average JTSL was 2.46 ± 0.38 mm. The conversion ratio between the ultrasonographic ACD and the average JTSL was 1.35. The predicted ACD using the regression equation of JTSL on the ultrasound anterior chamber depth (USACD) was 3.32 ± 0.54 mm. The corresponding value using the regression equation of JTSL and CCT on USACD was exactly the same, that is, 3.32 ± 0.54 mm. Conclusion: Incorporation of CCT into a regression equation does not improve the accuracy of the Smith technique.  相似文献   
70.
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